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
To evaluate the potential of high entropy alloys for marine applications,a new high entropy alloy coating of AlCrFeNiW_(0.2)Ti_(0.5)was designed and produced on Q235 steel via laser cladding.The microstructure,microha...To evaluate the potential of high entropy alloys for marine applications,a new high entropy alloy coating of AlCrFeNiW_(0.2)Ti_(0.5)was designed and produced on Q235 steel via laser cladding.The microstructure,microhardness and tribological performances sliding against YG6 cemented carbide,GCr15 steel and Si_(3)N_(4)ceramic in seawater were studied in detail.The AlCrFeNiW_(0.2)Ti_(0.5)coating showed an anomalous’sunflower-like’morphology and consisted of BCC and ordered B2 phases.The microhardness was approximately 692.5 HV,which was 5 times higher than substrate.The coating showed more excellent tribological performances than Q235 steel and SUS304,a typical material used in seawater environment,sliding against all three coupled balls in seawater.Besides,the wear and friction of AlCrFeNiW_(0.2)Ti_(0.5)coating sliding against YG6 in seawater were most mild.The main reason was the generation of Mg(OH)_(2),CaCO_(3),metal oxides and hydroxides and the formation of protective tribo-film on the worn surface of AlCrFeNiW_(0.2)Ti_(0.5)coating in the process of reciprocated sliding.This would effectively hinder the direct contact between the worn surfaces of AlCrFeNiW_(0.2)Ti_(0.5)coating and YG6 ball,resulting in a decrease of friction coefficient and wear rate.Thus the YG6 was an ideal coupled material for AlCrFeNiW_(0.2)Ti_(0.5)coating in seawater,and the coating would become a promising wear-resisting material in ocean environment.展开更多
In recent years,the coating prepared by laser cladding has attracted much attention in the field of wear research.In this work,AlCrFeNiMo_(0.5)Si_(x)(x=0,0.5,1.0,1.5,2.0)high-entropy alloy coatings were designed and p...In recent years,the coating prepared by laser cladding has attracted much attention in the field of wear research.In this work,AlCrFeNiMo_(0.5)Si_(x)(x=0,0.5,1.0,1.5,2.0)high-entropy alloy coatings were designed and prepared on Q235 steel by laser cladding.The effect of Si content on microstructure,microhardness and wear resistance of the coatings was studied in detail.The results indicate that the AlCrFeNiMo_(0.5)Si_(x) highentropy alloy coatings show an excellent bonding between substrate and the cladding layer.The AlCrFeNiMo_(0.5)Si_(x) coatings are composed of nano-precipitated phase with BCC structure and matrix with ordered B2 structure.With the addition of Si,the white phase(Cr,Mo)_(3)Si with cubic structure appears in the interdendritic,and the morphology of the coating(x=2.0)transforms into lamellar eutectic-like structures.The addition of Si enhances the microhardness and significantly improves the wear resistance of the coatings.As x increases from 0 to 2.0,the average hardness of the cladding zone increases from 632 HV to 835 HV,and the wear rate decreases from 1.64×10^(-5) mm^(3)·(N·m)^(-1) to 5.13×10^(-6) mm^(3)·(N·m)^(-1).When x≥1.5,the decreasing trend of the wear rate gradually slows down.The wear rates of Si1.5 and Si2.0 coatings are 5.85×10^(-6) mm^(3)·(N·m)^(-1) and 5.13×10^(-6) mm^(3)·(N·m)^(-1),respectively,which is an order of magnitude lower than that of Q235 steel.展开更多
21-4N(5Cr21Mn9Ni4N)is extensively employed in the production of engine valves,operating under severe conditions.Apart from withstanding high-temperature gas corrosion,it must also endure the impact of cylinder explosi...21-4N(5Cr21Mn9Ni4N)is extensively employed in the production of engine valves,operating under severe conditions.Apart from withstanding high-temperature gas corrosion,it must also endure the impact of cylinder explosion pressure.The predominant failure mode of 21-4N valves is abrasive wear.Surface coatings serve as an effective approach to prevent such failures.In this investigation,Laser cladding technology was utilized to fabricate AlCoCrFeNiTi high entropy alloy coatings onto the surfaces of 21-4N valves.According to the findings,the cladding zone has a normal dendritic microstructure,a good substrate-to-cladding layer interaction,and no obvious flaws.In terms of hardness,the cladding demonstrates an average hardness of 620 HV.The hardness has increased by 140%compared to the substrate.The average hardness of the cladding remains at approximately 520 HV even at elevated temperatures.Regarding frictional wear performance,between 400℃and 800℃,the cladding layer exhibits an average friction coefficient of 0.4,with the primary wear mechanisms being abrasive wear,adhesive wear,and a minor degree of plastic deformation.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
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
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
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
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
To solve the problems of deformation,micro-cracks,and residual tensile stress in laser cladding coatings,the technique of laser cladding with Fe-based memory alloy can be considered.However,the process of in-situ synt...To solve the problems of deformation,micro-cracks,and residual tensile stress in laser cladding coatings,the technique of laser cladding with Fe-based memory alloy can be considered.However,the process of in-situ synthesis of Fe-based memory alloy coatings is extremely complex.At present,there is no clear guidance scheme for its preparation process,which limits its promotion and application to some extent.Therefore,in this study,response surface methodology(RSM)was used to model the response surface between the target values and the cladding process parameters.The NSGA-2 algorithm was employed to optimize the process parameters.The results indicate that the composite optimization method consisting of RSM and the NSGA-2 algorithm can establish a more accurate model,with an error of less than 4.5%between the predicted and actual values.Based on this established model,the optimal scheme for process parameters corresponding to different target results can be rapidly obtained.The prepared coating exhibits a uniform structure,with no defects such as pores,cracks,and deformation.The surface roughness and microhardness of the coating are enhanced,the shaping quality of the coating is effectively improved,and the electrochemical corrosion performance of the coating in 3.5%NaCl solution is obviously better than that of the substrate,providing an important guide for engineering applications.展开更多
Based on the Miedema＇s formation heat model for binary alloys and the Toop＇s asymmetric model for ternary alloys, the formation heat, excess entropy, and activity coefficients of silicon ranging from 1 900 K to 4 10...Based on the Miedema＇s formation heat model for binary alloys and the Toop＇s asymmetric model for ternary alloys, the formation heat, excess entropy, and activity coefficients of silicon ranging from 1 900 K to 4 100 K in the Fe-Si-C melt formed during the laser cladding high silicon coatings process were calculated. The results indicated that all values of lnγ^0Si, ε^CSi,ρ^SiSi and ρ^CSi are negative in the temperature range and these values increase as the temperature increases. And all values of ε^SiSi and ρ^Si-CSi are positive and these values decrease with increasing temperature. The iso-activity lines of silicon are distributed axisymmetrically to the incident laser beam in the melt pool vertical to the laser scanning direction. And the iso-activity lines of silicon in the front of the melt pool along the laser scanning direction are more intensive than those in the back of the melt pool. The activity of silicon on the bottom of the melt pool is lower than that in the effecting center of laser beam on the top surface of the melt pool and it may be the important reason for the formation of the silicides and excellent metallurgical bonding between the laser cladding coating and the substrate.展开更多
The crack-free Ni60 A coating was fabricated on 45 steel substrate by laser cladding and the microstructure including solidification characteristics, phases constitution and phase distribution was systematically inves...The crack-free Ni60 A coating was fabricated on 45 steel substrate by laser cladding and the microstructure including solidification characteristics, phases constitution and phase distribution was systematically investigated. The high temperature friction and wear behavior of the cladding coating and substrate sliding against GCr15 ball under different loads was systematically evaluated. It was found that the coating has homogenous and fine microstructure consisting of γ（Ni） solid solution, a considerable amount of network Ni-Ni3 B eutectics, m^23C6 with the floret-shape structure and Cr B with the dark spot-shape structure uniformly distributing in interdendritic eutectics. The microhardness of the coating is about 2.6 times as much as that of the substrate. The coating produces higher friction values than the substrate under the same load condition, but the friction process on the coating keeps relatively stable. Wear rates of the coating are about 1/6.2 of that of the substrate under the higher load（300 g）. Wear mechanism of the substrate includes adhesion wear, abrasive wear, severe plastic deformation and oxidation wear, while that of the coating is merely a combination of mild abrasive wear and moderate oxidation wear.展开更多
Fe-based coating was produced on pure Ti substrate by the laser cladding technology. The composition and microstructure of the fabricated coating were analyzed by scanning electron microscopy （SEM）, X-ray diffracti...Fe-based coating was produced on pure Ti substrate by the laser cladding technology. The composition and microstructure of the fabricated coating were analyzed by scanning electron microscopy （SEM）, X-ray diffraction （XRD） and transmission electron microscopy （TEM） technique. The tribological properties were tested through sliding against AISI52100 steel ball at different normal loads and sliding speeds. Besides, the morphologies of the worn surfaces and wear debris were analyzed by scanning electron microscopy （SEM） and three dimensional （3D） non-contact surface mapping. The results show that the prepared Fe-based coating has a high hardness of about 860 HV0.2 and exhibits an average wear rate of （0.70-2.32）×10-6 mm3/（N-m）, showing that the Fe-based coating can greatly improve the wear resistance of pure Ti substrate. The wear mechanism of the coating involves moderate adhesive and abrasive wear.展开更多
A Y2O3 particle enhanced Ni/TiC composite coating was fabricated in-situ on a TC4 Ti alloy by laser surface cladding.The phase component,microstructure,composition distribution and properties of the composite layer we...A Y2O3 particle enhanced Ni/TiC composite coating was fabricated in-situ on a TC4 Ti alloy by laser surface cladding.The phase component,microstructure,composition distribution and properties of the composite layer were investigated.The composite layer has graded microstructures and compositions,due to the fast melting followed by rapid solidification and cooling during laser cladding.The TiC powders are completely dissolved into the melted layer during melting and segregated as fine dendrites when solidified.The size of TiC dendrites decreases with increasing depth.Y2O3 fine particles distribute in the whole clad layer.The Y2O3 particle enhanced Ni/TiC composite layer has a quite uniform hardness along depth with a maximum value of HV1380,which is 4 times higher than the initial hardness.The wear resistance of the Ti alloy is significantly improved after laser cladding due to the high hardness of the composite coating.展开更多
Al2O3-13%TiO2 （mass fraction） coatings, prepared by laser cladding on nickel-based alloy, were heated using high frequency induction sources. The coating microstructure and the interface between bond coating and cer...Al2O3-13%TiO2 （mass fraction） coatings, prepared by laser cladding on nickel-based alloy, were heated using high frequency induction sources. The coating microstructure and the interface between bond coating and ceramic coating were characterized by SEM, XRD and EDS. The results show that two-layer substructure exists in the ceramic coating： one layer evolving from fully melted region where the sintered grains grow fully; another layer resembling the liquid-phase-sintered structure consisting of three-dimensional net where the melted Al2O3 particles are embedded in the TiO2-rich matrix. The mechanism of the two-layer substructure formation is also explained in terms of the melting and flattening behavior of the powders during laser cladding processing. The spinel compounds NiAl2O4 and acicular compounds Cr2O3 are discovered in the interface between bond coating and ceramic coating. It proves that the chemical reactions in the laser cladding process will significantly enhance the coating adhesion.展开更多
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financially supported by the National Natural Science Foundation of China(Nos.51771041,51774065,51671044 and 51901116)the National Key Research and Development Program of China(No.2017YFA0403803)。
文摘To evaluate the potential of high entropy alloys for marine applications,a new high entropy alloy coating of AlCrFeNiW_(0.2)Ti_(0.5)was designed and produced on Q235 steel via laser cladding.The microstructure,microhardness and tribological performances sliding against YG6 cemented carbide,GCr15 steel and Si_(3)N_(4)ceramic in seawater were studied in detail.The AlCrFeNiW_(0.2)Ti_(0.5)coating showed an anomalous’sunflower-like’morphology and consisted of BCC and ordered B2 phases.The microhardness was approximately 692.5 HV,which was 5 times higher than substrate.The coating showed more excellent tribological performances than Q235 steel and SUS304,a typical material used in seawater environment,sliding against all three coupled balls in seawater.Besides,the wear and friction of AlCrFeNiW_(0.2)Ti_(0.5)coating sliding against YG6 in seawater were most mild.The main reason was the generation of Mg(OH)_(2),CaCO_(3),metal oxides and hydroxides and the formation of protective tribo-film on the worn surface of AlCrFeNiW_(0.2)Ti_(0.5)coating in the process of reciprocated sliding.This would effectively hinder the direct contact between the worn surfaces of AlCrFeNiW_(0.2)Ti_(0.5)coating and YG6 ball,resulting in a decrease of friction coefficient and wear rate.Thus the YG6 was an ideal coupled material for AlCrFeNiW_(0.2)Ti_(0.5)coating in seawater,and the coating would become a promising wear-resisting material in ocean environment.
基金supported by the National Natural Science Foundation of China(Nos.51771041,52101036 and 51901116)the National Key Research and Development Program of China(No.2018YFE0306103).
文摘In recent years,the coating prepared by laser cladding has attracted much attention in the field of wear research.In this work,AlCrFeNiMo_(0.5)Si_(x)(x=0,0.5,1.0,1.5,2.0)high-entropy alloy coatings were designed and prepared on Q235 steel by laser cladding.The effect of Si content on microstructure,microhardness and wear resistance of the coatings was studied in detail.The results indicate that the AlCrFeNiMo_(0.5)Si_(x) highentropy alloy coatings show an excellent bonding between substrate and the cladding layer.The AlCrFeNiMo_(0.5)Si_(x) coatings are composed of nano-precipitated phase with BCC structure and matrix with ordered B2 structure.With the addition of Si,the white phase(Cr,Mo)_(3)Si with cubic structure appears in the interdendritic,and the morphology of the coating(x=2.0)transforms into lamellar eutectic-like structures.The addition of Si enhances the microhardness and significantly improves the wear resistance of the coatings.As x increases from 0 to 2.0,the average hardness of the cladding zone increases from 632 HV to 835 HV,and the wear rate decreases from 1.64×10^(-5) mm^(3)·(N·m)^(-1) to 5.13×10^(-6) mm^(3)·(N·m)^(-1).When x≥1.5,the decreasing trend of the wear rate gradually slows down.The wear rates of Si1.5 and Si2.0 coatings are 5.85×10^(-6) mm^(3)·(N·m)^(-1) and 5.13×10^(-6) mm^(3)·(N·m)^(-1),respectively,which is an order of magnitude lower than that of Q235 steel.
基金Sponsored by the Project to Enhance the Innovative Capabilities of Science and Technology SMEs of Shandong Province(Grant No.2023TSGC0531).
文摘21-4N(5Cr21Mn9Ni4N)is extensively employed in the production of engine valves,operating under severe conditions.Apart from withstanding high-temperature gas corrosion,it must also endure the impact of cylinder explosion pressure.The predominant failure mode of 21-4N valves is abrasive wear.Surface coatings serve as an effective approach to prevent such failures.In this investigation,Laser cladding technology was utilized to fabricate AlCoCrFeNiTi high entropy alloy coatings onto the surfaces of 21-4N valves.According to the findings,the cladding zone has a normal dendritic microstructure,a good substrate-to-cladding layer interaction,and no obvious flaws.In terms of hardness,the cladding demonstrates an average hardness of 620 HV.The hardness has increased by 140%compared to the substrate.The average hardness of the cladding remains at approximately 520 HV even at elevated temperatures.Regarding frictional wear performance,between 400℃and 800℃,the cladding layer exhibits an average friction coefficient of 0.4,with the primary wear mechanisms being abrasive wear,adhesive wear,and a minor degree of plastic deformation.
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.
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.
基金financial supports from the National Natural Science Foundation of China-Youth Project(51801076)the Provincial Colleges and Universities Natural Science Research Project of Jiangsu Province(18KJB430009)+1 种基金the Postdoctoral Research Support Project of Jiangsu Province(1601055C)the Senior Talents Research Startup of Jiangsu University(14JDG126)。
文摘To solve the problems of deformation,micro-cracks,and residual tensile stress in laser cladding coatings,the technique of laser cladding with Fe-based memory alloy can be considered.However,the process of in-situ synthesis of Fe-based memory alloy coatings is extremely complex.At present,there is no clear guidance scheme for its preparation process,which limits its promotion and application to some extent.Therefore,in this study,response surface methodology(RSM)was used to model the response surface between the target values and the cladding process parameters.The NSGA-2 algorithm was employed to optimize the process parameters.The results indicate that the composite optimization method consisting of RSM and the NSGA-2 algorithm can establish a more accurate model,with an error of less than 4.5%between the predicted and actual values.Based on this established model,the optimal scheme for process parameters corresponding to different target results can be rapidly obtained.The prepared coating exhibits a uniform structure,with no defects such as pores,cracks,and deformation.The surface roughness and microhardness of the coating are enhanced,the shaping quality of the coating is effectively improved,and the electrochemical corrosion performance of the coating in 3.5%NaCl solution is obviously better than that of the substrate,providing an important guide for engineering applications.
基金National Natural Science Foundation of China (50474084)
文摘Based on the Miedema＇s formation heat model for binary alloys and the Toop＇s asymmetric model for ternary alloys, the formation heat, excess entropy, and activity coefficients of silicon ranging from 1 900 K to 4 100 K in the Fe-Si-C melt formed during the laser cladding high silicon coatings process were calculated. The results indicated that all values of lnγ^0Si, ε^CSi,ρ^SiSi and ρ^CSi are negative in the temperature range and these values increase as the temperature increases. And all values of ε^SiSi and ρ^Si-CSi are positive and these values decrease with increasing temperature. The iso-activity lines of silicon are distributed axisymmetrically to the incident laser beam in the melt pool vertical to the laser scanning direction. And the iso-activity lines of silicon in the front of the melt pool along the laser scanning direction are more intensive than those in the back of the melt pool. The activity of silicon on the bottom of the melt pool is lower than that in the effecting center of laser beam on the top surface of the melt pool and it may be the important reason for the formation of the silicides and excellent metallurgical bonding between the laser cladding coating and the substrate.
基金Project(2012AA040210)supported by the National High-Tech Research and Development Program of ChinaProject(510-C10293)supported by the Central Finance Special Fund to Support the Local University,ChinaProject(2010A090200048)supported by the Key Project of Industry,Education,Research of Guangdong Province and Ministry of Education,China
文摘The crack-free Ni60 A coating was fabricated on 45 steel substrate by laser cladding and the microstructure including solidification characteristics, phases constitution and phase distribution was systematically investigated. The high temperature friction and wear behavior of the cladding coating and substrate sliding against GCr15 ball under different loads was systematically evaluated. It was found that the coating has homogenous and fine microstructure consisting of γ（Ni） solid solution, a considerable amount of network Ni-Ni3 B eutectics, m^23C6 with the floret-shape structure and Cr B with the dark spot-shape structure uniformly distributing in interdendritic eutectics. The microhardness of the coating is about 2.6 times as much as that of the substrate. The coating produces higher friction values than the substrate under the same load condition, but the friction process on the coating keeps relatively stable. Wear rates of the coating are about 1/6.2 of that of the substrate under the higher load（300 g）. Wear mechanism of the substrate includes adhesion wear, abrasive wear, severe plastic deformation and oxidation wear, while that of the coating is merely a combination of mild abrasive wear and moderate oxidation wear.
基金Project (51045004) supported by the National Natural Science Foundation of ChinaProject (2006AA03A219) supported by Hi-tech Research and Development Program of ChinaProject (YYYJ-0913) supported by Knowledge Innovation Project in Chinese Academy of Sciences
文摘Fe-based coating was produced on pure Ti substrate by the laser cladding technology. The composition and microstructure of the fabricated coating were analyzed by scanning electron microscopy （SEM）, X-ray diffraction （XRD） and transmission electron microscopy （TEM） technique. The tribological properties were tested through sliding against AISI52100 steel ball at different normal loads and sliding speeds. Besides, the morphologies of the worn surfaces and wear debris were analyzed by scanning electron microscopy （SEM） and three dimensional （3D） non-contact surface mapping. The results show that the prepared Fe-based coating has a high hardness of about 860 HV0.2 and exhibits an average wear rate of （0.70-2.32）×10-6 mm3/（N-m）, showing that the Fe-based coating can greatly improve the wear resistance of pure Ti substrate. The wear mechanism of the coating involves moderate adhesive and abrasive wear.
基金Projects(51101096,51002093)supported by the National Natural Science Foundation of ChinaProject(1052nm05000)supported by Special Foundation of the Shanghai Science and Technology Commission for Nano-Materials ResearchProject(J51042)supported by Leading Academic Discipline Project of the Shanghai Education Commission,China
文摘A Y2O3 particle enhanced Ni/TiC composite coating was fabricated in-situ on a TC4 Ti alloy by laser surface cladding.The phase component,microstructure,composition distribution and properties of the composite layer were investigated.The composite layer has graded microstructures and compositions,due to the fast melting followed by rapid solidification and cooling during laser cladding.The TiC powders are completely dissolved into the melted layer during melting and segregated as fine dendrites when solidified.The size of TiC dendrites decreases with increasing depth.Y2O3 fine particles distribute in the whole clad layer.The Y2O3 particle enhanced Ni/TiC composite layer has a quite uniform hardness along depth with a maximum value of HV1380,which is 4 times higher than the initial hardness.The wear resistance of the Ti alloy is significantly improved after laser cladding due to the high hardness of the composite coating.
基金Project (59975046) supported by the National Natural Science Foundation of China
文摘Al2O3-13%TiO2 （mass fraction） coatings, prepared by laser cladding on nickel-based alloy, were heated using high frequency induction sources. The coating microstructure and the interface between bond coating and ceramic coating were characterized by SEM, XRD and EDS. The results show that two-layer substructure exists in the ceramic coating： one layer evolving from fully melted region where the sintered grains grow fully; another layer resembling the liquid-phase-sintered structure consisting of three-dimensional net where the melted Al2O3 particles are embedded in the TiO2-rich matrix. The mechanism of the two-layer substructure formation is also explained in terms of the melting and flattening behavior of the powders during laser cladding processing. The spinel compounds NiAl2O4 and acicular compounds Cr2O3 are discovered in the interface between bond coating and ceramic coating. It proves that the chemical reactions in the laser cladding process will significantly enhance the coating adhesion.
