Laser multi\|layer cladding experiments were performed on the substrate of DD3 single crystal with FGH95 powder as cladding material.The solidification microstructure in the sample was investigated.It was found that t...Laser multi\|layer cladding experiments were performed on the substrate of DD3 single crystal with FGH95 powder as cladding material.The solidification microstructure in the sample was investigated.It was found that the solidification microstructure was greatly influenced by the crystallography orientation of the substrate and the local solidification conditions.When the angle between the preferred orientation of the single crystal and the direction of heat flow in the cladding layer is less than 30°,single crystal cladding layers were acquired.Otherwise the crystallography orientation of the cladding layer will deviate from the orientation of the substrate and the microstructure with polycrystalline appears.Meanwhile,even when the experiments were performed on the same preferred crystal surface,the solidification microstructures will be different distinctly resulting from the variation of the local solidification conditions.The secondary arms were degenerated and the primary arm spacing was about 10\|20μm.Further investigation shows that the phases of the cladding layer are mainly made up ofγ,γ′,the flower\|likeγ/γ′eutectic and carbide.The morphology ofγ′was cubical and the size is less than 0.1μm.展开更多
By laser multi-layer cladding using a pulsed Nd-YAG irradiation the thickness of the cladding zone Mg-based alloys(ZM2 and ZM5) can reach about 1.0 mm.The microstructure of the substrate and the cladding zone was stud...By laser multi-layer cladding using a pulsed Nd-YAG irradiation the thickness of the cladding zone Mg-based alloys(ZM2 and ZM5) can reach about 1.0 mm.The microstructure of the substrate and the cladding zone was studied using optical microscope, scanning electron microscopy(SEM), X-ray diffractometry(XRD) and micro hardness analysis. It is observed that constituent of ZM5 alloy is δ+Mg 17Al 12, that of ZM2 alloy is α+MgZn+Mg 9Ce. That of cladding layer ZM2 alloy(L-ZM2) is Mg+Mg 2Zn 11+MgCe; while that of the cladding layer ZM5 alloy(L-ZM5) is Mg+Mg 32(Al, Zn) 49. The hardness of the cladding area can be increased to values above HV127. Very fine uniform microstructure and the produced new phases of nanometer/sub-micrometer order were obtained. Now, many repaired Mg-based alloy components have been passed by flying test in outside field.展开更多
The key parameters that characterize the morphological quality of multi-layer and multi-pass metal laser deposited parts are the surface roughness and the error between the actual printing height and the theoretical m...The key parameters that characterize the morphological quality of multi-layer and multi-pass metal laser deposited parts are the surface roughness and the error between the actual printing height and the theoretical model height.The Taguchi method was employed to establish the correlations between process parameter combinations and multi-objective characterization of metal deposition morphology(height error and roughness).Results show that using the signal-to-noise ratio and grey relational analysis,the optimal parameter combination for multi-layer and multi-pass deposition is determined as follows:laser power of 800 W,powder feeding rate of 0.3 r/min,step distance of 1.6 mm,and scanning speed of 20 mm/s.Subsequently,a Genetic Bayesian-back propagation(GB-BP)network is constructed to predict multi-objective responses.Compared with the traditional back propagation network,the GB-back propagation network improves the prediction accuracy of height error and surface roughness by 43.14%and 71.43%,respectively.This network can accurately predict the multi-objective characterization of morphological quality of multi-layer and multi-pass metal deposited parts.展开更多
A pulsed Nd: YAG laser is used in multi-layer cladding on ZM6 Mg base alloys. The microstructure is studied with an optical microscope and a scanning electron microscope (SEM). The composition within the layer was det...A pulsed Nd: YAG laser is used in multi-layer cladding on ZM6 Mg base alloys. The microstructure is studied with an optical microscope and a scanning electron microscope (SEM). The composition within the layer was determined by electron probe microanalysis (EPMA). X-ray diffraction (XRD) was also used to investigate the phase of constitutes of the cladding zone. The results show that microstructure in solidified cladding layer changes much when treated by high energy laser beam. The microstructure of the ZM6 alloy consists of a-Mg and Mg9Nd, while the L-ZM6 of a-Mg, MggNd and a-Zr. The depth of the cladding is over 1 mm. Many fine particles were found to be distributed homogeneously throughout the matrix and the columnar grain grows along substrate.展开更多
The Multi layer coating of Ni60 alloy was got by multi layer laser cladding. The height of the coating was about 12mm and the wall of the coating was perpendicular to the base. The microstructure of the coating was ...The Multi layer coating of Ni60 alloy was got by multi layer laser cladding. The height of the coating was about 12mm and the wall of the coating was perpendicular to the base. The microstructure of the coating was made up of fine dendrite. The conjunction between layers was good.展开更多
Multi-layer laser cladding manufacturing is a newly developed rapid manufacturing technology. It is a powerful tool for direct fabrication of three-dimensional fully dense metal components and part repairing. In this ...Multi-layer laser cladding manufacturing is a newly developed rapid manufacturing technology. It is a powerful tool for direct fabrication of three-dimensional fully dense metal components and part repairing. In this paper, the microstructure evolution and properties of 316L stainless steel deposited with this technology was investigated, compact components with properties similar to the as-cast and wrought annealed material was obtained. Cracking was eliminated by introducing of supersonic vibration and application of parameter adjustment technologies.展开更多
At present,the emerging solid-phase friction-based additive manufacturing technology,including friction rolling additive man-ufacturing(FRAM),can only manufacture simple single-pass components.In this study,multi-laye...At present,the emerging solid-phase friction-based additive manufacturing technology,including friction rolling additive man-ufacturing(FRAM),can only manufacture simple single-pass components.In this study,multi-layer multi-pass FRAM-deposited alumin-um alloy samples were successfully prepared using a non-shoulder tool head.The material flow behavior and microstructure of the over-lapped zone between adjacent layers and passes during multi-layer multi-pass FRAM deposition were studied using the hybrid 6061 and 5052 aluminum alloys.The results showed that a mechanical interlocking structure was formed between the adjacent layers and the adja-cent passes in the overlapped center area.Repeated friction and rolling of the tool head led to different degrees of lateral flow and plastic deformation of the materials in the overlapped zone,which made the recrystallization degree in the left and right edge zones of the over-lapped zone the highest,followed by the overlapped center zone and the non-overlapped zone.The tensile strength of the overlapped zone exceeded 90%of that of the single-pass deposition sample.It is proved that although there are uneven grooves on the surface of the over-lapping area during multi-layer and multi-pass deposition,they can be filled by the flow of materials during the deposition of the next lay-er,thus ensuring the dense microstructure and excellent mechanical properties of the overlapping area.The multi-layer multi-pass FRAM deposition overcomes the limitation of deposition width and lays the foundation for the future deposition of large-scale high-performance components.展开更多
Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,a...Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,as well as the wear resistance of the coatings.Besides,the effect of changing the laser melting process on the coatings was also investigated.The oxidation mass gain at 800–1200℃and the high-temperature oxidation behavior during high-temperature treatment for 1 h of two coated Zr alloy samples were studied.Results show that the Co coating and the Co-T800 coating have better resistance against high-temperature oxidation.After oxidizing at 1000℃for 1 h,the thickness of the oxide layer of the uncoated sample was 241.0μm,whereas that of the sample with Co-based coating is only 11.8–35.5μm.The friction wear test shows that the depth of the abrasion mark of the coated sample is only 1/2 of that of the substrate,indicating that the hardness and wear resistance of the Zr substrate are greatly improved.The disadvantage of Co-based coatings is the inferior corrosion resistance in 3.5wt%NaCl solution.展开更多
Bulge is a defect that causes geometrical inaccuracy and premature failure in the innovative incremental sheet forming (ISF) process. This study has two-fold objectives:(1) knowing the bulging behavior of a Cu clad tr...Bulge is a defect that causes geometrical inaccuracy and premature failure in the innovative incremental sheet forming (ISF) process. This study has two-fold objectives:(1) knowing the bulging behavior of a Cu clad tri-layered steel sheet as a function of forming conditions, and (2) analyzing the bending effect on bulging in an attempt to identify the associated mechanism. A series of ISF tests and bending analysis are performed to realize these objectives. From the cause-effect analysis, it is found that bulge formation in the layered sheet is sensitive to forming conditions in a way that bulging can be minimized utilizing annealed material and performing ISF with larger tool diameter and step size. The bending under tension analysis reveals that the formation of bulge is an outgrowth of bending moment that the forming tool applies on the sheet during ISF. Furthermore, the magnitude of bending moment depending upon the forming conditions varies from 0.046 to 10.24 N·m/m and causes a corresponding change in the mean bulge height from 0.07 to 0.91 mm. The bending moment governs bulging in layered sheet through a linear law. These findings lead to a conclusion that the bulge defect can be overcome by controlling the bending moment and the formula proposed can be helpful in this regards.展开更多
The high-entropy alloy composite coatings AlCu_(2)Ti(NiCr)_(2)-(WC)_(x)(x denotes powder feeding speeds,including 0,25,50,and 75 r/min)were prepared by plasma cladding using a hybrid mode of AlCu_(2)(NiCr)_(2)Ti cable...The high-entropy alloy composite coatings AlCu_(2)Ti(NiCr)_(2)-(WC)_(x)(x denotes powder feeding speeds,including 0,25,50,and 75 r/min)were prepared by plasma cladding using a hybrid mode of AlCu_(2)(NiCr)_(2)Ti cable-type welding wire(CWW)and tungsten carbide(WC)powder.The effect of WC powder feeding speed on the microstructure,hardness,and wear properties of the prepared coatings was investigated.The results show that the coatings consist of body-centered cubic main phases and face-centered cubic secondary phases,with carbide reinforcement phases formed due to the addition of WC.The hardness and wear resistance of the coatings are significantly improved compared to the TC11 substrate.When WC powder feeding speed is set at 50 r/min,the coating exhibits optimal wear resistance,with a minimum volume wear rate of 8.5869×10^(-6)mm^(3)·N^(-1)·m^(-1),greatly improving the wear properties of TC11 surface.The coincident CWW-powder plasma cladding provides a viable method for the preparation of highentropy alloy composite coatings with enhanced wear resistance.展开更多
Aseries of [(Fe_(0.6)Co_(0.2)Ni_(0.2))_(0.75-0.03x)B_(0.2)Si_(0.05+0.03x)]_(96)Nb_(4) amorphous alloy composite coatings were prepared by adjusting the silicon content(x=0,1,2,3,4,5,and 6)and their microstructures and...Aseries of [(Fe_(0.6)Co_(0.2)Ni_(0.2))_(0.75-0.03x)B_(0.2)Si_(0.05+0.03x)]_(96)Nb_(4) amorphous alloy composite coatings were prepared by adjusting the silicon content(x=0,1,2,3,4,5,and 6)and their microstructures and tribological properties were investigated by laser cladding technique.Additionally,the effect of Si on the glass forming ability(GFA)of the layers was understood.Results show that an appropriate Si content can refine the microstructure of the FeCoNiBSiNb laser cladding layers and improve the mechanical and tribological properties.The hardness of the coating layer increases monotonically with the Si content.At the Si content of 4.8at%(x=0),the coating layer exhibits a relatively low hardness(734.2HV 0.1).Conversely,at the silicon content of 13.44at%(x=3),the coating layer exhibits the highest hardness(1106HV 0.1).The non-crystalline content and tensile strength exhibit an initial increase,followed by a subsequent decrease.At x=2,the coating exhibits its maximum fracture strength(2880 MPa).However,when x>2,the fracture strength of the coating decreases with an increase in x.Conversely,with an increase in Si content,the wear volume loss initially decreases and then increases.At a Si content of 10.56at%(x=2),the coating exhibits the highest non-crystalline content(42%),the highest tensile strength(2880 MPa),and the most favorable dry friction performance.展开更多
The failure of mechanical components is mainly caused by three key mechanisms:wear,corrosion,and fatigue.Among these failure modes,wear of mechanical components notably increases energy consumption and leads to substa...The failure of mechanical components is mainly caused by three key mechanisms:wear,corrosion,and fatigue.Among these failure modes,wear of mechanical components notably increases energy consumption and leads to substantial economic losses.Fe-Cr-C-B-Ti-Y wear-resistant cladding metals were prepared by the plasma cladding method.The wear performance of the cladding metals was analyzed using an MLS-23 rubber wheel wet sand wear tester.X-ray diffraction,scanning electron microscope,electron backscatter diffraction,and transmission electron microscope were employed to investigate the phase composition and microstructure of the cladding metals,followed by a discussion of their strengthening and wear mechanisms.The results indicate that the microstructure of Fe-Cr-C-B-Ti-Y cladding metals is composed of austeniteγ-Fe,M_(23)(C,B)_(6)eutectic carbide,and TiC hard phase.As the Y_(2)O_(3)content increases,the hardness and wear resistance of the cladding metal show a trend of first increasing and then decreasing.When the Y_(2)O_(3)content is 0.4wt%,the precipitation of TiC hard phase and M_(23)(C,B)_(6)-type eutectic carbides reaches maximum,and the grain size is the finest.The cladding metal exhibits optimal formability,featuring the smallest wetting angle of 52.2°.Under this condition,the Rockwell hardness value of the cladding metal is 89.7 HRC,and the wear mass loss is 0.27 g.The dominant wear mechanism of cladding metals is abrasive wear,and the material removal process involves micro-cutting and plowing.展开更多
In order to enhance the wear resistance of 45 steel,a WC/Stellite 6 composite layer with 30%WC which with different morphologies(spherical and irregular)was prepared on the surface of 45 steel by laser cladding techno...In order to enhance the wear resistance of 45 steel,a WC/Stellite 6 composite layer with 30%WC which with different morphologies(spherical and irregular)was prepared on the surface of 45 steel by laser cladding technology.The effects of WC morphology on the phase composition,microstructure,microhardness,and wear resistance of the cladding layer were compared and analyzed.The res-ults show that the surface of the cladding layer was well formed.M_(23)C_(6),M_(7)C_(3),WC,and W_(2)C exist in both cladding layers.With the ad-dition of spherical WC,the diffraction peaks of γ-Co appear on the left side of the main peak of Co6W6C.The area of intergranular carbides accounts for a large proportion in the surface layer which with the fine grains.During the process of laser cladding the spherical WC particles with loose structure are prone to melting,including their interior.However,the melting amount of irregular WC particles is finite,which only occurs on the periphery of the particles,and the particle interior is relatively intact.The microhard-ness of two cladding layers gradient increases from the substrate to the surface layer.The surface layer added spherical WC has high-er microhardness,which reaches 790.6 HV1.Nevertheless,the wear resistance of the cladding layer added irregular WC is better than that of the cladding layer added spherical WC.The reason is because that the incompletely melted irregular WC particles are uni-formly distributed in the cladding layer which provided the support points for the cladding layer matrix during the wear process,the wear of the cladding layer by the grinding pair is reduced consequently.展开更多
Conventional Fe-C alloy parts used in mechanical transmission and braking systems exposed to the external environment often suffer from wear and corrosion failures.Surface coating strengthening technologies have been ...Conventional Fe-C alloy parts used in mechanical transmission and braking systems exposed to the external environment often suffer from wear and corrosion failures.Surface coating strengthening technologies have been explored to improve the surface performance and prolong service life of these parts.Among these technologies,laser cladding has shown promise in producing Fe-based alloy coatings with superior interfacial bonding properties to the Fe-C alloy substrate.Additionally,the microstructure of the Fe-based alloy coating is more uniform and the grain size is finer than that of surfacing welding,thermal spraying,and plasma cladding,and the oxide film of alloying elements on the coating surface can improve the coating performance.However,Fe-based alloy coatings produced by laser cladding typically exhibit lower hardness,lower wear resistance,corrosion resistance,and oxidation resistance compared to coatings based on Co and Ni alloys.Moreover,these coatings are susceptible to defects such as pores and cracks.To address these limitations,the incorporation of rare-earth oxides through doping in the laser cladding process has garnered significant attention.This approach has demonstrated substantial improvements in the microstructure and properties of Fe-based alloy coatings.This paper reviewed recent research on the structure and properties of laser-cladded Fe-based alloy coatings doped with various rare earth oxides,including La_(2)O_(3),CeO_(2),and Y_(2)O_(3).Specifically,it discussed the effects of rare earth oxides and their concentrations on the structure,hardness,friction,wear,corrosion,and oxidation characteristics of these coatings.Furthermore,the mechanisms by which rare earth oxides influence the coating’s structure and properties were summarized.This review aimed to serve as a valuable reference for the application and advancement of laser cladding technology for rare earth modified Fe-based alloy coatings.展开更多
Cladding light strippers(CLSs)are essential components for high-power monolithic fiber laser systems.Because they allow for bending of the fiber,which leads to an excellent stripping efficiency of light with a low ray...Cladding light strippers(CLSs)are essential components for high-power monolithic fiber laser systems.Because they allow for bending of the fiber,which leads to an excellent stripping efficiency of light with a low ray angle,refractive index-based CLSs have an advantage over the commonly used alternative approaches.However,conventional high-index CLSs overheat at relatively low input power as the maximum temperature,located in a hot-spot,increases linearly with the input power.This applies particularly to CLSs in thulium-based fiber systems,where very low power can already lead to extreme heat generation due to the high cladding material absorption around 2μm.Here,we investigate materials with a highly negative thermooptical coefficient combined with a refractive index closely above glass to distribute the stripped power and heat uniformly along an increased fiber length.Analyzing multiple CLS geometries for fiber diameters of 125 and 400μm,we show record-high maximum input powers for single-material CLSs of 21.8 W for the signal(2039 nm)and 675 W for the pump wavelength(793 nm).Transmitting excess light instead of overheating,this wavelength-adaptable self-protecting CLS concept is fast to apply onsite in the lab and reaches stripping efficiencies of>40 dB in the bent version.展开更多
In order to improve the surface properties of titanium alloys,a novel TiFeNiCuV high-entropy alloy(HEA)coating was prepared on a Ti−6Al−4V(TC4)substrate via laser cladding under different laser powers.The microstructu...In order to improve the surface properties of titanium alloys,a novel TiFeNiCuV high-entropy alloy(HEA)coating was prepared on a Ti−6Al−4V(TC4)substrate via laser cladding under different laser powers.The microstructure,microhardness,and friction wear properties of the coatings were systematically investigated.The results showed that at laser powers of 1200 and 2000 W,the microstructure of the coatings exhibited a core-shell dendritic structure.At 2800 W,the coatings displayed a daisy-like eutectic structure.The average hardness of the coatings reached HV 692.281 owing to solid-solution and fine-grain strengthening.Wear mechanisms of the coatings at room temperature primarily involved fatigue and slight oxidation wear.The total volume loss of the coatings was 4.22×10^(−3)mm^(3),which was 14.47%that of the TC4,indicating excellent wear resistance.展开更多
This work investigated tribological behavior and corrosion resistance of laser cladding(LC)Ti_(50)Nb_(15)V_(15)Zr_(5)Cr_(5)Al_(10)high-entropy alloy(HEA)coatings on Ti6Al4V substrates.Microstructural characterization ...This work investigated tribological behavior and corrosion resistance of laser cladding(LC)Ti_(50)Nb_(15)V_(15)Zr_(5)Cr_(5)Al_(10)high-entropy alloy(HEA)coatings on Ti6Al4V substrates.Microstructural characterization illustrated that there was only body centered cubic phase in the HEA coating.Besides,the coatings of different laser power all exhibited obviously higher hardness than the substrate.It is illustrated that the microstructure of the HEA coatings is composed of body centered cubic phase,and the temperature gradient contributes to the distribution difference between the equiaxed and columnar grains.Meanwhile,the relationships between the tribological behavior,corrosion resistance and alloying elements have been illustrated.The HEA coating with 2200 W holds the best wear and corrosion resistance.During the friction process,there are many oxides formed at high temperatures,and adhesive wear contributes most to the wear mechanism of the coatings.The wear volumes of the HEA coatings are only 24.7%to 45.5%of that of the Ti6Al4V substrate.Due to the alloying elements like Cr and Al,there is dense passive film formed during the corrosion process,thereby leading to better corrosion resistance of the coatings.The corrosion rates of the HEA coatings with 2200 W and Ti6Al4V substrate are 5.34×10^(-3)mm/a and 2.69×10^(-2)mm/a,respectively.展开更多
The huge impact kinetic energy cannot be quickly dissipated by the energy-absorbing structure and transferred to the other vehicle through the car body structure,which will cause structural damage and threaten the liv...The huge impact kinetic energy cannot be quickly dissipated by the energy-absorbing structure and transferred to the other vehicle through the car body structure,which will cause structural damage and threaten the lives of the occupants.Therefore,it is necessary to understand the laws of energy conversion,dissipation and transfer during train collisions.This study proposes a multi-layer progressive analysis method of energy flow during train collisions,considering the characteristics of the train.In this method,the train collision system is divided into conversion,dissipation,and transfer layers from the perspective of the train,collision interface,and car body structure to analyze the energy conversion,dissipation and transfer characteristics.Taking the collision process of a rail train as an example,a train collision energy transfer path analysis model was established based on power flow theory.The results show that when the maximum mean acceleration of the vehicle meets the standard requirements,the jerk may exceed the allowable limit of the human body,and there is a risk of injury to the occupants of a secondary collision.The decay rate of the collision energy along the direction of train operation reaches 79%.As the collision progresses,the collision energy gradually converges in the structure with holes,and the structure deforms when the gathered energy is greater than the maximum energy the structure can withstand.The proposed method helps to understand the train collision energy flow law and provides theoretical support for the train crashworthiness design in the future.展开更多
The growing incidence of cyberattacks necessitates a robust and effective Intrusion Detection Systems(IDS)for enhanced network security.While conventional IDSs can be unsuitable for detecting different and emerging at...The growing incidence of cyberattacks necessitates a robust and effective Intrusion Detection Systems(IDS)for enhanced network security.While conventional IDSs can be unsuitable for detecting different and emerging attacks,there is a demand for better techniques to improve detection reliability.This study introduces a new method,the Deep Adaptive Multi-Layer Attention Network(DAMLAN),to boost the result of intrusion detection on network data.Due to its multi-scale attention mechanisms and graph features,DAMLAN aims to address both known and unknown intrusions.The real-world NSL-KDD dataset,a popular choice among IDS researchers,is used to assess the proposed model.There are 67,343 normal samples and 58,630 intrusion attacks in the training set,12,833 normal samples,and 9711 intrusion attacks in the test set.Thus,the proposed DAMLAN method is more effective than the standard models due to the consideration of patterns by the attention layers.The experimental performance of the proposed model demonstrates that it achieves 99.26%training accuracy and 90.68%testing accuracy,with precision reaching 98.54%on the training set and 96.64%on the testing set.The recall and F1 scores again support the model with training set values of 99.90%and 99.21%and testing set values of 86.65%and 91.37%.These results provide a strong basis for the claims made regarding the model’s potential to identify intrusion attacks and affirm its relatively strong overall performance,irrespective of type.Future work would employ more attempts to extend the scalability and applicability of DAMLAN for real-time use in intrusion detection systems.展开更多
In order to enable efficient and cost-effective rehabilitation of surface-worn hydraulic supports,the synthesis and characterization of a novel Ti(N,B)/AISI431 composite coating formed on the surface of 27MnSi steel a...In order to enable efficient and cost-effective rehabilitation of surface-worn hydraulic supports,the synthesis and characterization of a novel Ti(N,B)/AISI431 composite coating formed on the surface of 27MnSi steel are explored via an exothermic in-situ reaction using the ultra-high speed laser cladding(EHLA in German)technique in combination with direct reaction synthesis(DRS).The aim is to mitigate the high residual stress and interfacial stress gradient in the remanufactured AISI431 coating on 27SiMn steel substrate and enhance surface wear resistance.The microstructure,phase composition and interface characteristics are carefully investigated.Much improved wear performance of the composite coating is revealed,mainly attributed to the in-situ formed Ti(N,B)precipitates,refined microstructure,broadened interface zone and reduced residual stress,benefited from the exothermic in-situ Ti(N,B)-reaction.The potential of combining ultra-high speed laser cladding with DRS is demonstrated to create coatings with tailored properties,providing valuable insights for developing advanced wear-resistant materials for industrial applications using EHLA.展开更多
基金National Key Basic Research Development Program me of china(No.G2000067205-3)
文摘Laser multi\|layer cladding experiments were performed on the substrate of DD3 single crystal with FGH95 powder as cladding material.The solidification microstructure in the sample was investigated.It was found that the solidification microstructure was greatly influenced by the crystallography orientation of the substrate and the local solidification conditions.When the angle between the preferred orientation of the single crystal and the direction of heat flow in the cladding layer is less than 30°,single crystal cladding layers were acquired.Otherwise the crystallography orientation of the cladding layer will deviate from the orientation of the substrate and the microstructure with polycrystalline appears.Meanwhile,even when the experiments were performed on the same preferred crystal surface,the solidification microstructures will be different distinctly resulting from the variation of the local solidification conditions.The secondary arms were degenerated and the primary arm spacing was about 10\|20μm.Further investigation shows that the phases of the cladding layer are mainly made up ofγ,γ′,the flower\|likeγ/γ′eutectic and carbide.The morphology ofγ′was cubical and the size is less than 0.1μm.
文摘By laser multi-layer cladding using a pulsed Nd-YAG irradiation the thickness of the cladding zone Mg-based alloys(ZM2 and ZM5) can reach about 1.0 mm.The microstructure of the substrate and the cladding zone was studied using optical microscope, scanning electron microscopy(SEM), X-ray diffractometry(XRD) and micro hardness analysis. It is observed that constituent of ZM5 alloy is δ+Mg 17Al 12, that of ZM2 alloy is α+MgZn+Mg 9Ce. That of cladding layer ZM2 alloy(L-ZM2) is Mg+Mg 2Zn 11+MgCe; while that of the cladding layer ZM5 alloy(L-ZM5) is Mg+Mg 32(Al, Zn) 49. The hardness of the cladding area can be increased to values above HV127. Very fine uniform microstructure and the produced new phases of nanometer/sub-micrometer order were obtained. Now, many repaired Mg-based alloy components have been passed by flying test in outside field.
基金National Natural Science Foundation of China(52175237)。
文摘The key parameters that characterize the morphological quality of multi-layer and multi-pass metal laser deposited parts are the surface roughness and the error between the actual printing height and the theoretical model height.The Taguchi method was employed to establish the correlations between process parameter combinations and multi-objective characterization of metal deposition morphology(height error and roughness).Results show that using the signal-to-noise ratio and grey relational analysis,the optimal parameter combination for multi-layer and multi-pass deposition is determined as follows:laser power of 800 W,powder feeding rate of 0.3 r/min,step distance of 1.6 mm,and scanning speed of 20 mm/s.Subsequently,a Genetic Bayesian-back propagation(GB-BP)network is constructed to predict multi-objective responses.Compared with the traditional back propagation network,the GB-back propagation network improves the prediction accuracy of height error and surface roughness by 43.14%and 71.43%,respectively.This network can accurately predict the multi-objective characterization of morphological quality of multi-layer and multi-pass metal deposited parts.
基金This work was supported by shenyang Liming aeroengine Group Corporation AVIVI under Grant No.00-04-06
文摘A pulsed Nd: YAG laser is used in multi-layer cladding on ZM6 Mg base alloys. The microstructure is studied with an optical microscope and a scanning electron microscope (SEM). The composition within the layer was determined by electron probe microanalysis (EPMA). X-ray diffraction (XRD) was also used to investigate the phase of constitutes of the cladding zone. The results show that microstructure in solidified cladding layer changes much when treated by high energy laser beam. The microstructure of the ZM6 alloy consists of a-Mg and Mg9Nd, while the L-ZM6 of a-Mg, MggNd and a-Zr. The depth of the cladding is over 1 mm. Many fine particles were found to be distributed homogeneously throughout the matrix and the columnar grain grows along substrate.
文摘The Multi layer coating of Ni60 alloy was got by multi layer laser cladding. The height of the coating was about 12mm and the wall of the coating was perpendicular to the base. The microstructure of the coating was made up of fine dendrite. The conjunction between layers was good.
基金supported by the National Natural Science Foundation of China under the Grant No.50375096
文摘Multi-layer laser cladding manufacturing is a newly developed rapid manufacturing technology. It is a powerful tool for direct fabrication of three-dimensional fully dense metal components and part repairing. In this paper, the microstructure evolution and properties of 316L stainless steel deposited with this technology was investigated, compact components with properties similar to the as-cast and wrought annealed material was obtained. Cracking was eliminated by introducing of supersonic vibration and application of parameter adjustment technologies.
基金supported by the National Key Research and Development Program of China(No.2022YFB3404700)the National Natural Science Foundation of China(Nos.52105313 and 52275299)+2 种基金the Research and Development Program of Beijing Municipal Education Commission,China(No.KM202210005036)the Natural Science Foundation of Chongqing,China(No.CSTB2023NSCQ-MSX0701)the National Defense Basic Research Projects of China(No.JCKY2022405C002).
文摘At present,the emerging solid-phase friction-based additive manufacturing technology,including friction rolling additive man-ufacturing(FRAM),can only manufacture simple single-pass components.In this study,multi-layer multi-pass FRAM-deposited alumin-um alloy samples were successfully prepared using a non-shoulder tool head.The material flow behavior and microstructure of the over-lapped zone between adjacent layers and passes during multi-layer multi-pass FRAM deposition were studied using the hybrid 6061 and 5052 aluminum alloys.The results showed that a mechanical interlocking structure was formed between the adjacent layers and the adja-cent passes in the overlapped center area.Repeated friction and rolling of the tool head led to different degrees of lateral flow and plastic deformation of the materials in the overlapped zone,which made the recrystallization degree in the left and right edge zones of the over-lapped zone the highest,followed by the overlapped center zone and the non-overlapped zone.The tensile strength of the overlapped zone exceeded 90%of that of the single-pass deposition sample.It is proved that although there are uneven grooves on the surface of the over-lapping area during multi-layer and multi-pass deposition,they can be filled by the flow of materials during the deposition of the next lay-er,thus ensuring the dense microstructure and excellent mechanical properties of the overlapping area.The multi-layer multi-pass FRAM deposition overcomes the limitation of deposition width and lays the foundation for the future deposition of large-scale high-performance components.
基金National Natural Science Foundation of China(52071126)Natural Science Foundation of Tianjin City,China(22JCQNJC01240)+2 种基金Central Guidance on Local Science and Technology Development Fund of Hebei Province(226Z1009G)Special Funds for Science and Technology Innovation in Hebei(2022X19)Anhui Provincial Natural Science Foundation(2308085ME135)。
文摘Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,as well as the wear resistance of the coatings.Besides,the effect of changing the laser melting process on the coatings was also investigated.The oxidation mass gain at 800–1200℃and the high-temperature oxidation behavior during high-temperature treatment for 1 h of two coated Zr alloy samples were studied.Results show that the Co coating and the Co-T800 coating have better resistance against high-temperature oxidation.After oxidizing at 1000℃for 1 h,the thickness of the oxide layer of the uncoated sample was 241.0μm,whereas that of the sample with Co-based coating is only 11.8–35.5μm.The friction wear test shows that the depth of the abrasion mark of the coated sample is only 1/2 of that of the substrate,indicating that the hardness and wear resistance of the Zr substrate are greatly improved.The disadvantage of Co-based coatings is the inferior corrosion resistance in 3.5wt%NaCl solution.
基金the financial help and technical support that King Abdulaziz University provided for this research work
文摘Bulge is a defect that causes geometrical inaccuracy and premature failure in the innovative incremental sheet forming (ISF) process. This study has two-fold objectives:(1) knowing the bulging behavior of a Cu clad tri-layered steel sheet as a function of forming conditions, and (2) analyzing the bending effect on bulging in an attempt to identify the associated mechanism. A series of ISF tests and bending analysis are performed to realize these objectives. From the cause-effect analysis, it is found that bulge formation in the layered sheet is sensitive to forming conditions in a way that bulging can be minimized utilizing annealed material and performing ISF with larger tool diameter and step size. The bending under tension analysis reveals that the formation of bulge is an outgrowth of bending moment that the forming tool applies on the sheet during ISF. Furthermore, the magnitude of bending moment depending upon the forming conditions varies from 0.046 to 10.24 N·m/m and causes a corresponding change in the mean bulge height from 0.07 to 0.91 mm. The bending moment governs bulging in layered sheet through a linear law. These findings lead to a conclusion that the bulge defect can be overcome by controlling the bending moment and the formula proposed can be helpful in this regards.
基金National Natural Science Foundation of China(51764038)Gansu Science and Technology Planning Project(2022JR5RA314,22YF7WA151,22YF7GA138,23CXGA0151)+1 种基金Gansu Provincial Department of Education:Industrial Support Plan Project(2022CYZC-31)Gansu Provincial Association of Science and Technology Innovation Driving Force Project(GXH20230817-10)。
文摘The high-entropy alloy composite coatings AlCu_(2)Ti(NiCr)_(2)-(WC)_(x)(x denotes powder feeding speeds,including 0,25,50,and 75 r/min)were prepared by plasma cladding using a hybrid mode of AlCu_(2)(NiCr)_(2)Ti cable-type welding wire(CWW)and tungsten carbide(WC)powder.The effect of WC powder feeding speed on the microstructure,hardness,and wear properties of the prepared coatings was investigated.The results show that the coatings consist of body-centered cubic main phases and face-centered cubic secondary phases,with carbide reinforcement phases formed due to the addition of WC.The hardness and wear resistance of the coatings are significantly improved compared to the TC11 substrate.When WC powder feeding speed is set at 50 r/min,the coating exhibits optimal wear resistance,with a minimum volume wear rate of 8.5869×10^(-6)mm^(3)·N^(-1)·m^(-1),greatly improving the wear properties of TC11 surface.The coincident CWW-powder plasma cladding provides a viable method for the preparation of highentropy alloy composite coatings with enhanced wear resistance.
文摘Aseries of [(Fe_(0.6)Co_(0.2)Ni_(0.2))_(0.75-0.03x)B_(0.2)Si_(0.05+0.03x)]_(96)Nb_(4) amorphous alloy composite coatings were prepared by adjusting the silicon content(x=0,1,2,3,4,5,and 6)and their microstructures and tribological properties were investigated by laser cladding technique.Additionally,the effect of Si on the glass forming ability(GFA)of the layers was understood.Results show that an appropriate Si content can refine the microstructure of the FeCoNiBSiNb laser cladding layers and improve the mechanical and tribological properties.The hardness of the coating layer increases monotonically with the Si content.At the Si content of 4.8at%(x=0),the coating layer exhibits a relatively low hardness(734.2HV 0.1).Conversely,at the silicon content of 13.44at%(x=3),the coating layer exhibits the highest hardness(1106HV 0.1).The non-crystalline content and tensile strength exhibit an initial increase,followed by a subsequent decrease.At x=2,the coating exhibits its maximum fracture strength(2880 MPa).However,when x>2,the fracture strength of the coating decreases with an increase in x.Conversely,with an increase in Si content,the wear volume loss initially decreases and then increases.At a Si content of 10.56at%(x=2),the coating exhibits the highest non-crystalline content(42%),the highest tensile strength(2880 MPa),and the most favorable dry friction performance.
文摘The failure of mechanical components is mainly caused by three key mechanisms:wear,corrosion,and fatigue.Among these failure modes,wear of mechanical components notably increases energy consumption and leads to substantial economic losses.Fe-Cr-C-B-Ti-Y wear-resistant cladding metals were prepared by the plasma cladding method.The wear performance of the cladding metals was analyzed using an MLS-23 rubber wheel wet sand wear tester.X-ray diffraction,scanning electron microscope,electron backscatter diffraction,and transmission electron microscope were employed to investigate the phase composition and microstructure of the cladding metals,followed by a discussion of their strengthening and wear mechanisms.The results indicate that the microstructure of Fe-Cr-C-B-Ti-Y cladding metals is composed of austeniteγ-Fe,M_(23)(C,B)_(6)eutectic carbide,and TiC hard phase.As the Y_(2)O_(3)content increases,the hardness and wear resistance of the cladding metal show a trend of first increasing and then decreasing.When the Y_(2)O_(3)content is 0.4wt%,the precipitation of TiC hard phase and M_(23)(C,B)_(6)-type eutectic carbides reaches maximum,and the grain size is the finest.The cladding metal exhibits optimal formability,featuring the smallest wetting angle of 52.2°.Under this condition,the Rockwell hardness value of the cladding metal is 89.7 HRC,and the wear mass loss is 0.27 g.The dominant wear mechanism of cladding metals is abrasive wear,and the material removal process involves micro-cutting and plowing.
基金supported by the National Natural Science Foundation of China(52161007)Science and Technology Planning Project of Guangdong Province of China(20170902,20180902)+1 种基金Science and Technology Planning Project of Yangjiang City of Guangdong Province(SDZX2020009)Research project of Shenzhen city(JSGG20210420091802007).
文摘In order to enhance the wear resistance of 45 steel,a WC/Stellite 6 composite layer with 30%WC which with different morphologies(spherical and irregular)was prepared on the surface of 45 steel by laser cladding technology.The effects of WC morphology on the phase composition,microstructure,microhardness,and wear resistance of the cladding layer were compared and analyzed.The res-ults show that the surface of the cladding layer was well formed.M_(23)C_(6),M_(7)C_(3),WC,and W_(2)C exist in both cladding layers.With the ad-dition of spherical WC,the diffraction peaks of γ-Co appear on the left side of the main peak of Co6W6C.The area of intergranular carbides accounts for a large proportion in the surface layer which with the fine grains.During the process of laser cladding the spherical WC particles with loose structure are prone to melting,including their interior.However,the melting amount of irregular WC particles is finite,which only occurs on the periphery of the particles,and the particle interior is relatively intact.The microhard-ness of two cladding layers gradient increases from the substrate to the surface layer.The surface layer added spherical WC has high-er microhardness,which reaches 790.6 HV1.Nevertheless,the wear resistance of the cladding layer added irregular WC is better than that of the cladding layer added spherical WC.The reason is because that the incompletely melted irregular WC particles are uni-formly distributed in the cladding layer which provided the support points for the cladding layer matrix during the wear process,the wear of the cladding layer by the grinding pair is reduced consequently.
基金supported by the Jiangxi Provincial Natural Science Foundation of China(Grant number 20224BAB204049)the National Natural Science Foundation of China(Grant number 52205194)the Fund Project of Jiangxi Provincial Department of Education(Grant number GJJ2200602)。
文摘Conventional Fe-C alloy parts used in mechanical transmission and braking systems exposed to the external environment often suffer from wear and corrosion failures.Surface coating strengthening technologies have been explored to improve the surface performance and prolong service life of these parts.Among these technologies,laser cladding has shown promise in producing Fe-based alloy coatings with superior interfacial bonding properties to the Fe-C alloy substrate.Additionally,the microstructure of the Fe-based alloy coating is more uniform and the grain size is finer than that of surfacing welding,thermal spraying,and plasma cladding,and the oxide film of alloying elements on the coating surface can improve the coating performance.However,Fe-based alloy coatings produced by laser cladding typically exhibit lower hardness,lower wear resistance,corrosion resistance,and oxidation resistance compared to coatings based on Co and Ni alloys.Moreover,these coatings are susceptible to defects such as pores and cracks.To address these limitations,the incorporation of rare-earth oxides through doping in the laser cladding process has garnered significant attention.This approach has demonstrated substantial improvements in the microstructure and properties of Fe-based alloy coatings.This paper reviewed recent research on the structure and properties of laser-cladded Fe-based alloy coatings doped with various rare earth oxides,including La_(2)O_(3),CeO_(2),and Y_(2)O_(3).Specifically,it discussed the effects of rare earth oxides and their concentrations on the structure,hardness,friction,wear,corrosion,and oxidation characteristics of these coatings.Furthermore,the mechanisms by which rare earth oxides influence the coating’s structure and properties were summarized.This review aimed to serve as a valuable reference for the application and advancement of laser cladding technology for rare earth modified Fe-based alloy coatings.
文摘Cladding light strippers(CLSs)are essential components for high-power monolithic fiber laser systems.Because they allow for bending of the fiber,which leads to an excellent stripping efficiency of light with a low ray angle,refractive index-based CLSs have an advantage over the commonly used alternative approaches.However,conventional high-index CLSs overheat at relatively low input power as the maximum temperature,located in a hot-spot,increases linearly with the input power.This applies particularly to CLSs in thulium-based fiber systems,where very low power can already lead to extreme heat generation due to the high cladding material absorption around 2μm.Here,we investigate materials with a highly negative thermooptical coefficient combined with a refractive index closely above glass to distribute the stripped power and heat uniformly along an increased fiber length.Analyzing multiple CLS geometries for fiber diameters of 125 and 400μm,we show record-high maximum input powers for single-material CLSs of 21.8 W for the signal(2039 nm)and 675 W for the pump wavelength(793 nm).Transmitting excess light instead of overheating,this wavelength-adaptable self-protecting CLS concept is fast to apply onsite in the lab and reaches stripping efficiencies of>40 dB in the bent version.
基金the National Natural Science Foundation of China(Nos.52001037,U2037601,U21A2048)the National Key Research and Development Program of China(No.2022YFB3709300).
文摘In order to improve the surface properties of titanium alloys,a novel TiFeNiCuV high-entropy alloy(HEA)coating was prepared on a Ti−6Al−4V(TC4)substrate via laser cladding under different laser powers.The microstructure,microhardness,and friction wear properties of the coatings were systematically investigated.The results showed that at laser powers of 1200 and 2000 W,the microstructure of the coatings exhibited a core-shell dendritic structure.At 2800 W,the coatings displayed a daisy-like eutectic structure.The average hardness of the coatings reached HV 692.281 owing to solid-solution and fine-grain strengthening.Wear mechanisms of the coatings at room temperature primarily involved fatigue and slight oxidation wear.The total volume loss of the coatings was 4.22×10^(−3)mm^(3),which was 14.47%that of the TC4,indicating excellent wear resistance.
基金Projects(2022YFC2406000,52201067)supported by the National Natural Science Foundation of ChinaProject(2019BT02C629)supported by the Guangdong Special Support Program,China+8 种基金Project(2022GDASZH-2022010107)supported by the Guangdong Academy of Science Projects,ChinaProject(2022GDASZH-2022010203-003)supported by GDAS Projects of International Cooperation Platform of Science and Technology,ChinaProject(2022B1515250004)supported by the Guangdong Basic and Applied Basic Research Foundation,ChinaProjects(2023B1212120008,2023B1212060045)supported by the Guangdong Province Science and Technology Plan Projects,ChinaProject(2024KTSCX191)supported by the Guangdong Province General University Characteristic Innovation Project,ChinaProject(SKXRC202403)supported by the Guangdong Association for Science and Technology,ChinaProjects(QT-2023-038,QT2024-016)supported by the Young Talent Support Project of Guangzhou Association for Science and Technology,ChinaProject(023AFB057)supported by the Natural Science Foundation of Hubei Province,ChinaProject(2023780200040009603)supported by the Jiangmen Science and Technology Plan Projects,China。
文摘This work investigated tribological behavior and corrosion resistance of laser cladding(LC)Ti_(50)Nb_(15)V_(15)Zr_(5)Cr_(5)Al_(10)high-entropy alloy(HEA)coatings on Ti6Al4V substrates.Microstructural characterization illustrated that there was only body centered cubic phase in the HEA coating.Besides,the coatings of different laser power all exhibited obviously higher hardness than the substrate.It is illustrated that the microstructure of the HEA coatings is composed of body centered cubic phase,and the temperature gradient contributes to the distribution difference between the equiaxed and columnar grains.Meanwhile,the relationships between the tribological behavior,corrosion resistance and alloying elements have been illustrated.The HEA coating with 2200 W holds the best wear and corrosion resistance.During the friction process,there are many oxides formed at high temperatures,and adhesive wear contributes most to the wear mechanism of the coatings.The wear volumes of the HEA coatings are only 24.7%to 45.5%of that of the Ti6Al4V substrate.Due to the alloying elements like Cr and Al,there is dense passive film formed during the corrosion process,thereby leading to better corrosion resistance of the coatings.The corrosion rates of the HEA coatings with 2200 W and Ti6Al4V substrate are 5.34×10^(-3)mm/a and 2.69×10^(-2)mm/a,respectively.
基金Supported by the National Natural Science Foundation of China(Grant No.52172409)Postdoctoral Innovation Talents Support Program(Grant No.BX20240298)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.2682024GF023)Heilongjiang Province Postdoctoral Foundation Project(Grant No.LBH-Z23041).
文摘The huge impact kinetic energy cannot be quickly dissipated by the energy-absorbing structure and transferred to the other vehicle through the car body structure,which will cause structural damage and threaten the lives of the occupants.Therefore,it is necessary to understand the laws of energy conversion,dissipation and transfer during train collisions.This study proposes a multi-layer progressive analysis method of energy flow during train collisions,considering the characteristics of the train.In this method,the train collision system is divided into conversion,dissipation,and transfer layers from the perspective of the train,collision interface,and car body structure to analyze the energy conversion,dissipation and transfer characteristics.Taking the collision process of a rail train as an example,a train collision energy transfer path analysis model was established based on power flow theory.The results show that when the maximum mean acceleration of the vehicle meets the standard requirements,the jerk may exceed the allowable limit of the human body,and there is a risk of injury to the occupants of a secondary collision.The decay rate of the collision energy along the direction of train operation reaches 79%.As the collision progresses,the collision energy gradually converges in the structure with holes,and the structure deforms when the gathered energy is greater than the maximum energy the structure can withstand.The proposed method helps to understand the train collision energy flow law and provides theoretical support for the train crashworthiness design in the future.
基金Nourah bint Abdulrahman University for funding this project through the Researchers Supporting Project(PNURSP2025R319)Riyadh,Saudi Arabia and Prince Sultan University for covering the article processing charges(APC)associated with this publication.Special acknowledgement to Automated Systems&Soft Computing Lab(ASSCL),Prince Sultan University,Riyadh,Saudi Arabia.
文摘The growing incidence of cyberattacks necessitates a robust and effective Intrusion Detection Systems(IDS)for enhanced network security.While conventional IDSs can be unsuitable for detecting different and emerging attacks,there is a demand for better techniques to improve detection reliability.This study introduces a new method,the Deep Adaptive Multi-Layer Attention Network(DAMLAN),to boost the result of intrusion detection on network data.Due to its multi-scale attention mechanisms and graph features,DAMLAN aims to address both known and unknown intrusions.The real-world NSL-KDD dataset,a popular choice among IDS researchers,is used to assess the proposed model.There are 67,343 normal samples and 58,630 intrusion attacks in the training set,12,833 normal samples,and 9711 intrusion attacks in the test set.Thus,the proposed DAMLAN method is more effective than the standard models due to the consideration of patterns by the attention layers.The experimental performance of the proposed model demonstrates that it achieves 99.26%training accuracy and 90.68%testing accuracy,with precision reaching 98.54%on the training set and 96.64%on the testing set.The recall and F1 scores again support the model with training set values of 99.90%and 99.21%and testing set values of 86.65%and 91.37%.These results provide a strong basis for the claims made regarding the model’s potential to identify intrusion attacks and affirm its relatively strong overall performance,irrespective of type.Future work would employ more attempts to extend the scalability and applicability of DAMLAN for real-time use in intrusion detection systems.
基金financially supported by the National Key Research and Development Program of China(No.2023YFB4606200)Technical Development Foundation of China Academy of Machinery Science and Technology Group(No.812201Q9)+2 种基金Fundamental Research Funds of National Institute of Metrology of China(No.AKYRC2401)Beijing Natural Science Foundation(No.2222093)the National Key Research and Development Program of China(No.2021YFB3702003)。
文摘In order to enable efficient and cost-effective rehabilitation of surface-worn hydraulic supports,the synthesis and characterization of a novel Ti(N,B)/AISI431 composite coating formed on the surface of 27MnSi steel are explored via an exothermic in-situ reaction using the ultra-high speed laser cladding(EHLA in German)technique in combination with direct reaction synthesis(DRS).The aim is to mitigate the high residual stress and interfacial stress gradient in the remanufactured AISI431 coating on 27SiMn steel substrate and enhance surface wear resistance.The microstructure,phase composition and interface characteristics are carefully investigated.Much improved wear performance of the composite coating is revealed,mainly attributed to the in-situ formed Ti(N,B)precipitates,refined microstructure,broadened interface zone and reduced residual stress,benefited from the exothermic in-situ Ti(N,B)-reaction.The potential of combining ultra-high speed laser cladding with DRS is demonstrated to create coatings with tailored properties,providing valuable insights for developing advanced wear-resistant materials for industrial applications using EHLA.
