This study investigated enhancing the wear resistance of Ti6Al4V alloys for medical applications by incorporating Ti C nanoreinforcements using advanced spark plasma sintering(SPS). The addition of up to 2.5wt% Ti C s...This study investigated enhancing the wear resistance of Ti6Al4V alloys for medical applications by incorporating Ti C nanoreinforcements using advanced spark plasma sintering(SPS). The addition of up to 2.5wt% Ti C significantly improved the mechanical properties, including a notable 18.2% increase in hardness(HV 332). Fretting wear tests against 316L stainless steel(SS316L) balls demonstrated a 20wt%–22wt% reduction in wear volume in the Ti6Al4V/Ti C composites compared with the monolithic alloy. Microstructural analysis revealed that Ti C reinforcement controlled the grain orientation and reduced the β-phase content, which contributed to enhanced mechanical properties. The monolithic alloy exhibited a Widmanstätten lamellar microstructure, while increasing the Ti C content modified the wear mechanisms from ploughing and adhesion(0–0.5wt%) to pitting and abrasion(1wt%–2.5wt%). At higher reinforcement levels, the formation of a robust oxide layer through tribo-oxide treatment effectively reduced the wear volume by minimizing the abrasive effects and plastic deformation. This study highlights the potential of SPS-mediated Ti C reinforcement as a transformative approach for improving the performance of Ti6Al4V alloys, paving the way for advanced medical applications.展开更多
本文探讨Art to Wear即“可以穿的艺术”,其中大部分作品为服装,少量作品是帽子和首饰。通过分析Art to Wear代表艺术家,解读Art to Wear艺术作品,从而探讨美国20世纪60年代到80年代女性艺术家群体如何以艺术为媒介对自身经历进行叙述...本文探讨Art to Wear即“可以穿的艺术”,其中大部分作品为服装,少量作品是帽子和首饰。通过分析Art to Wear代表艺术家,解读Art to Wear艺术作品,从而探讨美国20世纪60年代到80年代女性艺术家群体如何以艺术为媒介对自身经历进行叙述性表现。60年代末70年代初处于美国女性主义的第二次浪潮,众多美国名校的年轻白人女大学生,不断为女性的参政、就业、医疗、最低工资等争取更多的权利,而到了80年代遭到美国保守主义的强烈打击,追求自由平等的女性主义运动跌入低谷。第二次女性主义运动的跌宕正是Art to Wear艺术运动的发展时期,艺术学院在读青年女生们发起Art to Wear艺术运动,她们在保守主义与激进主义的影响下寻求精神、生活的平衡,极力反叛女性束身塑形来博得男性视觉愉悦、通过同性的嫉妒来肯定自身价值。她们对家庭、事业、社会地位开始深思,通过作品叙述对社会性别与身份认定的迷茫,表达保守与激进思想的内心纠结。展开更多
In-situ formed high Mn steel coating reinforced by carbides was formed by laser surface alloying(LSA).Laser alloyed layers on 1Cr18Ni9Ti steel with Mn+W_(2)C(specimen A),Mn+NiWC(specimen B)and Mn+SiC(specimen C)powder...In-situ formed high Mn steel coating reinforced by carbides was formed by laser surface alloying(LSA).Laser alloyed layers on 1Cr18Ni9Ti steel with Mn+W_(2)C(specimen A),Mn+NiWC(specimen B)and Mn+SiC(specimen C)powders were fabricated to improve the wear and corrosion behavior of 1Cr18Ni9Ti steel blades in high speed mixers.Microstructure evolution,phases,element distribution,microhardness,wear and corrosion behavior of the laser alloyed layers were investigated.Results indicated that high Mn steel matrix composites with undissolved W_(2)C,WC and other in-situ formed carbides were formed by LSA with Mn+W_(2)C and Mn+NiWC while SiC totally dissolved into the high Mn matrix when adding Mn+SiC.Ni as the binding phase in Ni-WC powder decreased the crack sensitivity of the alloyed layer as compared with the addition of W_(2)C powder.An improvement in average microhardness was achieved in the matrix in specimen A,B and C,with the value of 615,602 and 277 HV_(0.5),while that of the substrate was 212 HV_(0.5).The increase of microhardness,wear and corrosion resistance is highly corelated to microstructure,formed phases,type and content of carbides,micro-hardness and toughness of the alloyed layers.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
Large portions of the tunnel boring machine(TBM)construction cost are attributed to disc cutter consumption,and assessing the disc cutter's wear level can help determine the optimal time to replace the disc cutter...Large portions of the tunnel boring machine(TBM)construction cost are attributed to disc cutter consumption,and assessing the disc cutter's wear level can help determine the optimal time to replace the disc cutter.Therefore,the need to monitor disc cutter wear in real-time has emerged as a technical challenge for TBMs.In this study,real-time disc cutter wear monitoring is developed based on sound and vibration sensors.For this purpose,the microphone and accelerometer were used to record the sound and vibration signals of cutting three different types of rocks with varying abrasions on a laboratory scale.The relationship between disc cutter wear and the sound and vibration signal was determined by comparing the measurements of disc cutter wear with the signal plots for each sample.The features extracted from the signals showed that the sound and vibration signals are impacted by the progression of disc wear during the rock-cutting process.The signal features obtained from the rock-cutting operation were utilized to verify the machine learning techniques.The results showed that the multilayer perceptron(MLP),random subspace-based decision tree(RS-DT),DT,and random forest(RF)methods could predict the wear level of the disc cutter with an accuracy of 0.89,0.951,0.951,and 0.927,respectively.Based on the accuracy of the models and the confusion matrix,it was found that the RS-DT model has the best estimate for predicting the level of disc wear.This research has developed a method that can potentially determine when to replace a tool and assess disc wear in real-time.展开更多
The good combination of mechanical and wear properties for cemented carbides is crucial.In this work,the wear behavior of functionally graded cemented carbide(FGCC)and non-graded cemented carbide(CC),with CoNiFeCr mul...The good combination of mechanical and wear properties for cemented carbides is crucial.In this work,the wear behavior of functionally graded cemented carbide(FGCC)and non-graded cemented carbide(CC),with CoNiFeCr multi-principal-element alloy(MPEA)binder,has been investigated by performing sliding wear tests and composition characterization.The results showed that compared with CC,FGCC had higher hardness,stronger fracture toughness,better wear performance,and similar TRS.FGCCs exhibited lower wear rates(3.44×10^(−7)–6.95×10^(−6)mm^(3)/(N m))and coefficients of friction(COFs)(0.27–0.39)than CCs from RT to 600℃due to mitigation of multiple risks caused by binder removal,fragmentation and pull-out of WC grains,high-temperature oxidation and softening.In the low-temperature wear stage,the MPEA binder underwent dynamic recrystallization(DRX)and twinning deformation before removing from the surface.The binder removal caused dislocation pile-ups and stacking faults(SFs)to form under high stress,resulting in fragmentation and pull-out of WC grains.The low-temperature wear was dominated by abrasive wear and adhesive wear,with a low wear rate and a high and unstable COF.In the high-temperature wear stage,initial pitting oxidation of WC grains generated many subgrain boundaries,reducing heat transfer and exacerbating oxidation,resulting in an oxide layer enriched with WO3,Mx Oy,and MWO4.High-temperature wear was dominated by oxidation wear and high-temperature softening,with a high wear rate and a low and smooth COF.The results from the present study do not only provide theoretical guidance for an understanding of the antiwear mechanism of WC-CoNiFeCr,but also a new approach for the preparation of cemented carbides with high wear resistance.展开更多
WC particles reinforced CoCrFeNiMo high-entropy alloy(HEA)composite coatings were prepared on Cr12MoV steel successfully by laser cladding technology to improve the wear resistance of substrates.Effect of WC content o...WC particles reinforced CoCrFeNiMo high-entropy alloy(HEA)composite coatings were prepared on Cr12MoV steel successfully by laser cladding technology to improve the wear resistance of substrates.Effect of WC content on microstructure and wear property of the composite coatings was studied in detail.Large numbers of carbides with four main types:primary carbide crystals,eutectic structures,massive crystals growing along the periphery of the remaining WC particles and incompletely fused WC particles,were found to exist in the WC/CoCrFeNiMo composite coatings.With increasing WC content,the microhardness of coatings is gradually improved while the average friction coefficients follow the opposite trend due to solid solution strengthening and second phase strengthening effect.The maximum microhardness and minimum friction coefficient are HV_(0.2)689.7 and 0.72,respectively,for the composite coating with 30 wt.%WC,the wear resistance of the substrate is improved significantly,the wear mechanisms are spalling wear and abrasive wear due to their high microhardness.展开更多
Efficient tool condition monitoring techniques help to realize intelligent management of tool life and reduce tool usage costs.In this paper,the influence of different wear degrees of ball-end milling cutters on the t...Efficient tool condition monitoring techniques help to realize intelligent management of tool life and reduce tool usage costs.In this paper,the influence of different wear degrees of ball-end milling cutters on the texture shape of machining tool marks is investigated,and a method is proposed for predicting the wear state(including the position and degree of tool wear)of ball-end milling cutters based on entropy measurement of tool mark texture images.Firstly,data samples are prepared through wear experiments,and the change law of the tool mark texture shape with the tool wear state is analyzed.Then,a two-dimensional sample entropy algorithm is developed to quantify the texture morphology.Finally,the processing parameters and tool attitude are integrated into the prediction process to predict the wear value and wear position of the ball end milling cutter.After testing,the correlation between the predicted value and the standard value of the proposed tool condition monitoring method reaches 95.32%,and the accuracy reaches 82.73%,indicating that the proposed method meets the requirement of tool condition monitoring.展开更多
This paper focuses on the use of rotary-percussive drilling for hard rocks.In order to improve efficiency and reduce costs,it is essential to understand how operational parameters,bit wear,and drilling performance are...This paper focuses on the use of rotary-percussive drilling for hard rocks.In order to improve efficiency and reduce costs,it is essential to understand how operational parameters,bit wear,and drilling performance are related.A model is presented therein that combines multibody dynamics and discrete element method(DEM)to investigate the influences of operational parameters and bit wear on the rate of penetration and wear characteristics.The model accurately captures the motion of the bit and recreates rock using the cutting sieving result.Field experimental results validate the rod dynamic behavior,rock recreating model,and coupling model in the simulation.The findings indicate that hammer pressure significantly influences the rate of penetration and wear depth of the bit,and there is an optimal range for economical hammer pressure.The wear coefficient has a major effect on the rate of penetration,when wear coefficient is between 1/3 and 2/3.Increasing the wear coefficient can reduce drill bit button pressure and wear depth at the same drill distance.Gauge button loss increases the rate of penetration due to higher pressure on the remaining buttons,which also accelerates destruction of the bit.Furthermore,a more evenly distributed button on the bit enhances the rate of penetration(ROP)when the same number of buttons is lost.展开更多
Stainless steel parts with complex shape can be fabricated using additive manufacturing,which do not rely on molds and dies.However,coarse dendrites induced by repeated heating of additive manufacturing result in weak...Stainless steel parts with complex shape can be fabricated using additive manufacturing,which do not rely on molds and dies.However,coarse dendrites induced by repeated heating of additive manufacturing result in weak properties,which limits its application.In this study,an in-situ ultrasonic rolling(UR)device was developed to assist the laser directed energy deposition(LDED)process.The microstructural characteristics,as well as the microhardness and wear behavior,were studied for the 316L stainless steel manufactured by in-situ ultrasonic rolling assisted LDED.It is found that austenite,ferrite,and small Si oxides are the main constituents of both the LDED and LDED-UR alloy samples.Under the severe plastic deformation of ultrasonic rolling,the long-branched ferrites by LDED are transformed into the rod-like phases by LDED-UR.Meanwhile,the ferrite is more uniformly distributed in the LDED-UR alloy sample compared with that in LDED alloy sample.Columnar grains with the size of 97.85μm appear in the LDED alloy sample,which is larger than the fully equiaxed grains(22.35μm)of the LDED-UR alloy.The hardness of the LDED-UR alloy sample is about 266.13±13.62 HV_(0.2),which is larger than that of the LDED alloy sample(212.93±12.85 HV_(0.2)).Meanwhile,the wear resistance is also greatly enhanced by applying the assisted in-situ ultrasonic rolling.The achieved high wear resistance can be ascribed to the uniformly distributed hard matter(ferrites)and the impedance of dislocations by high fraction of grain boundaries.Abrasive wear and adhesive wear are identified as the primary wear mechanisms of the studied alloy.Gaining an in-depth understanding of the relationship between wear mechanisms and microstructures offers an effective approach in manufacturing high wear resistant alloys suitable for use in harsh working environments.展开更多
The TZM alloys with different contents of ZrO_(2)were prepared by powder metallurgy and rolling,and the grain size,hardness,and abrasive wear resistance of TZM alloy were studied.The abrasive wear test of TZM alloy wa...The TZM alloys with different contents of ZrO_(2)were prepared by powder metallurgy and rolling,and the grain size,hardness,and abrasive wear resistance of TZM alloy were studied.The abrasive wear test of TZM alloy was conducted under the conditions of 10,15,and 20 N and abrasive particle sizes of 7,11,18,and 38μm.The results show that the added ZrO_(2)particles in TZM alloy are mainly distributed at the grain boundaries.The grains of TZM alloy containing 1.5wt%ZrO_(2)are significantly refined,and the hardness is increased by 16%.The wear test results show that TZM alloy containing 1.5wt%ZrO_(2)has the lowest mass loss rate and excellent wear resistance under all loads and abrasive sizes,and the wear performance is improved by 12%.The ZrO_(2)with high hardness becomes the main bearer of the load,and as the second-phase,it hinders the abrasive particles from entering the matrix and effectively resists the scratch of the abrasive particles,which is the main reason for the excellent wear resistance.展开更多
The morphological description of wear particles in lubricating oil is crucial for wear state monitoring and fault diagnosis in aero-engines.Accurately and comprehensively acquiring three-dimensional(3D)morphological d...The morphological description of wear particles in lubricating oil is crucial for wear state monitoring and fault diagnosis in aero-engines.Accurately and comprehensively acquiring three-dimensional(3D)morphological data of these particles has became a key focus in wear debris analysis.Herein,we develop a novel multi-view polarization-sensitive optical coherence tomography(PS-OCT)method to achieve accurate 3D morphology detection and reconstruction of aero-engine lubricant wear particles,effectively resolving occlusion-induced information loss while enabling material-specific characterization.The particle morphology is captured by multi-view imaging,followed by filtering,sharpening,and contour recognition.The method integrates advanced registration algorithms with Poisson reconstruction to generate high-precision 3D models.This approach not only provides accurate 3D morphological reconstruction but also mitigates information loss caused by particle occlusion,ensuring model completeness.Furthermore,by collecting polarization characteristics of typical metals and their oxides in aero-engine lubricants,this work comprehensively characterizes and comparatively analyzes particle polarization properties using Stokes vectors,polarization uniformity,and cumulative phase retardation,and obtains a three-dimensional model containing polarization information.Ultimately,the proposed method enables multidimensional information acquisition for the reliable identification of abrasive particle types.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
The impact-abrasive wear behavior of high-C martensitic steel was investigated,taking into account varying carbon(C)contents and different tempering temperatures.The evaluation was done through comprehensive microstru...The impact-abrasive wear behavior of high-C martensitic steel was investigated,taking into account varying carbon(C)contents and different tempering temperatures.The evaluation was done through comprehensive microstructural characterization,analysis of worn surface morphology,and measurement of key performance like impact toughness and surface hardening.The findings demonstrate that increasing C content and tempering temperature both has a positive effect on wear resistance,with C content exhibiting a more pronounced influence compared to the tempering temperature.The improved wear resistance of the steel with higher C content and tempering at a higher temperature can be attributed to its enhanced impact toughness.This increase in impact toughness is primarily a result of microstructural refinement and alterations in carbide morphology.Moreover,cyclic impact loading induces surface hardening due to dislocation strengthening within the martensite and the retained austenite,leading to an increase in surface hardness.The combination of surface hardening and excellent impact toughness synergistically contributes to the overall improved wear resistance observed in the experimental steel with higher C content after tempering at a higher temperature.Additionally,the dominant features observed on the worn surface are scratches and substrate delamination,indicative of a wear mechanism of the experimental steels characterized by micro-cutting/ploughing and fatigue wear.展开更多
The microstructural evolution,mechanical properties,and wear behavior of medium manganese steels(MMSs)with varying aluminum(Al)contents were investigated.It was observed that the microstructure of MMS transferred from...The microstructural evolution,mechanical properties,and wear behavior of medium manganese steels(MMSs)with varying aluminum(Al)contents were investigated.It was observed that the microstructure of MMS transferred from a predominantly martensitic phase(in the Al-free state)to a ferrite/martensite or ferrite/austenite duplex structure with increasing Al content.The hardness of MMS decreased with Al addition,while the impact absorbed energy and yield strength were optimized in 2%Al-containing variant.Frictional wear tests demonstrated that 2 wt.%Al-MMS exhibited superior wear resistance due to the twinning-induced plasticity effect.Conversely,under impact abrasion wear conditions,the Al-free MMS displayed the lowest mass loss,attributing to high surface hardness and remarkable work hardening capacity.These findings indicates that Al content-tailored MMSs can be selectively applied in different wear environments,with 2 wt.%Al-MMS being optimal for static load conditions and the Al-free MMS for dynamic impact abrasion scenarios.展开更多
CrN coatings are also employed to protect structural materials in nuclear power plants.It should be noted that the preparation process utilizing physical vapor deposition(PVD)techniques inevitably entails certain defe...CrN coatings are also employed to protect structural materials in nuclear power plants.It should be noted that the preparation process utilizing physical vapor deposition(PVD)techniques inevitably entails certain defects.Such a phenomenon will affect the protective properties of CrN coatings.In this study,low-energy laser shock peening(LE-LSP)with varying energies was employed for the post-treatment of CrN coatings.The effects of different laser energy LE-LSP treatments on the surface morphology,crystal structure and fretting wear properties of CrN coatings were investigated.The results revealed that the surface of the CrN coatings subjected to LE-LSP underwent significant plastic deformation and displayed a regular texture structure.The surface roughness and Vickers hardness of the CrN coatings exhibit a significant increase.Under a laser energy of 150 mJ,the surface hardness exhibits a maximum increase of 2.35 times.The residual stress of CrN coatings diminishes with the augmentation of laser energy due to the formation of surface cracks.Following LE-LSP treatment,the columnar crystal structure of the CrN coating was disrupted and fragmented into fine grains due to the impact force.As the laser energy augments,the fragmented CrN grains undergo further compaction.During fretting wear,all specimens were in the gross slip regime.The wear mechanism of the CrN coating,120 and 150 mJ specimens are primarily dominated by abrasive wear,and accompanied by oxidative wear.For specimens treated with 30,60 and 90 mJ,the predominant wear mechanisms are mainly peeling and abrasive wear,and accompanied by oxidative wear.Both the wear area and wear volume initially increase and then decrease as the laser energy increases.The 150 mJ specimen exhibited the smallest wear area and wear volume of all tested specimens.The wear volume was reduced by 76.32%when compared to that of the CrN coating.This study complements the existing research on PVD/LSP composite strengthening techniques.Introduces a novel post-treatment methodology for PVD coatings.Provides certain theoretical support for subsequent PVD/LSP composite strengthening.展开更多
To elucidate the wear mechanisms of the scraper in shield tunneling through sandy pebble strata,this study aims to achieve high efficiency and low wear during the tunneling process.We evaluate the operational paramete...To elucidate the wear mechanisms of the scraper in shield tunneling through sandy pebble strata,this study aims to achieve high efficiency and low wear during the tunneling process.We evaluate the operational parameters and tool wear characteristics of a 9-m diameter spoke-type shield machine used on the Beijing Daxing Airport Line.The analysis focuses on the wear values of the scrapers and rippers,wear of the scraper in different wear forms,and scraper wear relative to the position of the rippers obtained from the field.The study yielded the following conclusions.The wear values of scrapers on different spokes vary significantly owing to ripper protection.The wear of the scrapers can be categorized into six types:tooth chipping,local damage of teeth,wear of side teeth,wave-type of wear,wear on intermediate teeth,and flat wear,with the majority exhibiting wear on the side and intermediate teeth.The 0°spoke maintained the initial shape of the scrapers,making it more suitable for tunneling in sandy pebble strata.Based on the differences in the relative positions of the ripper and scraper,a model is proposed to determine the ripper plowing influence area.It was found that this area depends on the geological conditions of the soil;thus,the influence angle of ripper plowing in the considered sandy pebble strata is determined to be between 35°and 50°.The results obtained in this study provide a theoretical reference for optimizing scraper layouts in shield construction,even when operating under varying geological conditions.展开更多
The wear of work rolls significantly affects the production efficiency and product quality.However,existing methods for wear assessment fail to effectively quantify work roll surface wear conditions,thereby affecting ...The wear of work rolls significantly affects the production efficiency and product quality.However,existing methods for wear assessment fail to effectively quantify work roll surface wear conditions,thereby affecting the quality control of steel strips and maintenance strategies for rolls.To accurately assess the wear conditions of hot-rolling work rolls,this study initially established an apparatus for capturing high-precision roll surfaces images.Subsequently,a quantitative assessment of common surface wear morphologies was conducted,and a hot-rolling work roll surface wear dataset was constructed.The MobileNetV2 convolutional neural network(CNN),augmented by transfer learning,was employed to develop a MobileNetV2-wear detection and classification(WDC)surface wear grading model.A comparison with mainstream CNN models revealed that the MobileNetV2-WDC model achieved high-speed(21.92 ms)and accurate(96.86%)grading with minimal model parameters(2.27 M)and size(27 M),meeting the industrial efficiency and practicality requirements.A visual analysis of the model classification errors was conducted,outlining paths for further optimization.This study provides an efficient and accurate solution for detecting and grading surface wear on hot-rolling work rolls,enhancing product quality and extending the lifespan of rolls.展开更多
文摘This study investigated enhancing the wear resistance of Ti6Al4V alloys for medical applications by incorporating Ti C nanoreinforcements using advanced spark plasma sintering(SPS). The addition of up to 2.5wt% Ti C significantly improved the mechanical properties, including a notable 18.2% increase in hardness(HV 332). Fretting wear tests against 316L stainless steel(SS316L) balls demonstrated a 20wt%–22wt% reduction in wear volume in the Ti6Al4V/Ti C composites compared with the monolithic alloy. Microstructural analysis revealed that Ti C reinforcement controlled the grain orientation and reduced the β-phase content, which contributed to enhanced mechanical properties. The monolithic alloy exhibited a Widmanstätten lamellar microstructure, while increasing the Ti C content modified the wear mechanisms from ploughing and adhesion(0–0.5wt%) to pitting and abrasion(1wt%–2.5wt%). At higher reinforcement levels, the formation of a robust oxide layer through tribo-oxide treatment effectively reduced the wear volume by minimizing the abrasive effects and plastic deformation. This study highlights the potential of SPS-mediated Ti C reinforcement as a transformative approach for improving the performance of Ti6Al4V alloys, paving the way for advanced medical applications.
文摘本文探讨Art to Wear即“可以穿的艺术”,其中大部分作品为服装,少量作品是帽子和首饰。通过分析Art to Wear代表艺术家,解读Art to Wear艺术作品,从而探讨美国20世纪60年代到80年代女性艺术家群体如何以艺术为媒介对自身经历进行叙述性表现。60年代末70年代初处于美国女性主义的第二次浪潮,众多美国名校的年轻白人女大学生,不断为女性的参政、就业、医疗、最低工资等争取更多的权利,而到了80年代遭到美国保守主义的强烈打击,追求自由平等的女性主义运动跌入低谷。第二次女性主义运动的跌宕正是Art to Wear艺术运动的发展时期,艺术学院在读青年女生们发起Art to Wear艺术运动,她们在保守主义与激进主义的影响下寻求精神、生活的平衡,极力反叛女性束身塑形来博得男性视觉愉悦、通过同性的嫉妒来肯定自身价值。她们对家庭、事业、社会地位开始深思,通过作品叙述对社会性别与身份认定的迷茫,表达保守与激进思想的内心纠结。
文摘In-situ formed high Mn steel coating reinforced by carbides was formed by laser surface alloying(LSA).Laser alloyed layers on 1Cr18Ni9Ti steel with Mn+W_(2)C(specimen A),Mn+NiWC(specimen B)and Mn+SiC(specimen C)powders were fabricated to improve the wear and corrosion behavior of 1Cr18Ni9Ti steel blades in high speed mixers.Microstructure evolution,phases,element distribution,microhardness,wear and corrosion behavior of the laser alloyed layers were investigated.Results indicated that high Mn steel matrix composites with undissolved W_(2)C,WC and other in-situ formed carbides were formed by LSA with Mn+W_(2)C and Mn+NiWC while SiC totally dissolved into the high Mn matrix when adding Mn+SiC.Ni as the binding phase in Ni-WC powder decreased the crack sensitivity of the alloyed layer as compared with the addition of W_(2)C powder.An improvement in average microhardness was achieved in the matrix in specimen A,B and C,with the value of 615,602 and 277 HV_(0.5),while that of the substrate was 212 HV_(0.5).The increase of microhardness,wear and corrosion resistance is highly corelated to microstructure,formed phases,type and content of carbides,micro-hardness and toughness of the alloyed layers.
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.
文摘Large portions of the tunnel boring machine(TBM)construction cost are attributed to disc cutter consumption,and assessing the disc cutter's wear level can help determine the optimal time to replace the disc cutter.Therefore,the need to monitor disc cutter wear in real-time has emerged as a technical challenge for TBMs.In this study,real-time disc cutter wear monitoring is developed based on sound and vibration sensors.For this purpose,the microphone and accelerometer were used to record the sound and vibration signals of cutting three different types of rocks with varying abrasions on a laboratory scale.The relationship between disc cutter wear and the sound and vibration signal was determined by comparing the measurements of disc cutter wear with the signal plots for each sample.The features extracted from the signals showed that the sound and vibration signals are impacted by the progression of disc wear during the rock-cutting process.The signal features obtained from the rock-cutting operation were utilized to verify the machine learning techniques.The results showed that the multilayer perceptron(MLP),random subspace-based decision tree(RS-DT),DT,and random forest(RF)methods could predict the wear level of the disc cutter with an accuracy of 0.89,0.951,0.951,and 0.927,respectively.Based on the accuracy of the models and the confusion matrix,it was found that the RS-DT model has the best estimate for predicting the level of disc wear.This research has developed a method that can potentially determine when to replace a tool and assess disc wear in real-time.
基金financially supported by the National Key Research and Development Program of China(No.2021YFB3701800)Special funding support for the Yuelu Mountain National University Science and Technology City“Ranking the Top of the List”Research Project:(Tunnel Boring Machine High-performance Long-life Cutting Tools)the State Key Laboratory of Powder Metallurgy,Central South University,Changsha,China.
文摘The good combination of mechanical and wear properties for cemented carbides is crucial.In this work,the wear behavior of functionally graded cemented carbide(FGCC)and non-graded cemented carbide(CC),with CoNiFeCr multi-principal-element alloy(MPEA)binder,has been investigated by performing sliding wear tests and composition characterization.The results showed that compared with CC,FGCC had higher hardness,stronger fracture toughness,better wear performance,and similar TRS.FGCCs exhibited lower wear rates(3.44×10^(−7)–6.95×10^(−6)mm^(3)/(N m))and coefficients of friction(COFs)(0.27–0.39)than CCs from RT to 600℃due to mitigation of multiple risks caused by binder removal,fragmentation and pull-out of WC grains,high-temperature oxidation and softening.In the low-temperature wear stage,the MPEA binder underwent dynamic recrystallization(DRX)and twinning deformation before removing from the surface.The binder removal caused dislocation pile-ups and stacking faults(SFs)to form under high stress,resulting in fragmentation and pull-out of WC grains.The low-temperature wear was dominated by abrasive wear and adhesive wear,with a low wear rate and a high and unstable COF.In the high-temperature wear stage,initial pitting oxidation of WC grains generated many subgrain boundaries,reducing heat transfer and exacerbating oxidation,resulting in an oxide layer enriched with WO3,Mx Oy,and MWO4.High-temperature wear was dominated by oxidation wear and high-temperature softening,with a high wear rate and a low and smooth COF.The results from the present study do not only provide theoretical guidance for an understanding of the antiwear mechanism of WC-CoNiFeCr,but also a new approach for the preparation of cemented carbides with high wear resistance.
基金Project(2021YFC2801904)supported by the National Key R&D Program of ChinaProject(KY10100230067)supported by the Basic Product Innovation Research Project,China+3 种基金Projects(52271130,52305344)supported by the National Natural Science Foundation of ChinaProjects(ZR2020ME017,ZR2020QE186)supported by the Natural Science Foundation of Shandong Province,ChinaProjects(AMGM2024F11,AMGM2021F10,AMGM2023F06)supported by the Science Fund of Shandong Laboratory of Advanced Materials and Green Manufacturing at Yantai,ChinaProject(KY90200210015)supported by Leading Scientific Research Project of China National Nuclear Corporation(CNNC),China。
文摘WC particles reinforced CoCrFeNiMo high-entropy alloy(HEA)composite coatings were prepared on Cr12MoV steel successfully by laser cladding technology to improve the wear resistance of substrates.Effect of WC content on microstructure and wear property of the composite coatings was studied in detail.Large numbers of carbides with four main types:primary carbide crystals,eutectic structures,massive crystals growing along the periphery of the remaining WC particles and incompletely fused WC particles,were found to exist in the WC/CoCrFeNiMo composite coatings.With increasing WC content,the microhardness of coatings is gradually improved while the average friction coefficients follow the opposite trend due to solid solution strengthening and second phase strengthening effect.The maximum microhardness and minimum friction coefficient are HV_(0.2)689.7 and 0.72,respectively,for the composite coating with 30 wt.%WC,the wear resistance of the substrate is improved significantly,the wear mechanisms are spalling wear and abrasive wear due to their high microhardness.
基金Project(51975169)supported by the National Natural Science Foundation of ChinaProject(LH2022E085)supported by the Natural Science Foundation of Heilongjiang Province,China。
文摘Efficient tool condition monitoring techniques help to realize intelligent management of tool life and reduce tool usage costs.In this paper,the influence of different wear degrees of ball-end milling cutters on the texture shape of machining tool marks is investigated,and a method is proposed for predicting the wear state(including the position and degree of tool wear)of ball-end milling cutters based on entropy measurement of tool mark texture images.Firstly,data samples are prepared through wear experiments,and the change law of the tool mark texture shape with the tool wear state is analyzed.Then,a two-dimensional sample entropy algorithm is developed to quantify the texture morphology.Finally,the processing parameters and tool attitude are integrated into the prediction process to predict the wear value and wear position of the ball end milling cutter.After testing,the correlation between the predicted value and the standard value of the proposed tool condition monitoring method reaches 95.32%,and the accuracy reaches 82.73%,indicating that the proposed method meets the requirement of tool condition monitoring.
基金supported by the National Natural Science Foundation of China Youth Science Foundation of China(Grant No.52308388)the Key Project of High-speed Rail Joint Fund of National Natural Science Foundation of China(Grant No.U1934210).
文摘This paper focuses on the use of rotary-percussive drilling for hard rocks.In order to improve efficiency and reduce costs,it is essential to understand how operational parameters,bit wear,and drilling performance are related.A model is presented therein that combines multibody dynamics and discrete element method(DEM)to investigate the influences of operational parameters and bit wear on the rate of penetration and wear characteristics.The model accurately captures the motion of the bit and recreates rock using the cutting sieving result.Field experimental results validate the rod dynamic behavior,rock recreating model,and coupling model in the simulation.The findings indicate that hammer pressure significantly influences the rate of penetration and wear depth of the bit,and there is an optimal range for economical hammer pressure.The wear coefficient has a major effect on the rate of penetration,when wear coefficient is between 1/3 and 2/3.Increasing the wear coefficient can reduce drill bit button pressure and wear depth at the same drill distance.Gauge button loss increases the rate of penetration due to higher pressure on the remaining buttons,which also accelerates destruction of the bit.Furthermore,a more evenly distributed button on the bit enhances the rate of penetration(ROP)when the same number of buttons is lost.
基金supports from the National Natural Science Foundation of China(No.52305440)the Natural Science Foundation of Changsha City(Nos.kq2208272,kq2208274)+1 种基金the Tribology Science Fund of the State Key Laboratory of Tribology in Advanced Equipment(No.SKLTKF22B09)the National Key Research and Development Program of China(No.2022YFB3706902)were acknowledged.
文摘Stainless steel parts with complex shape can be fabricated using additive manufacturing,which do not rely on molds and dies.However,coarse dendrites induced by repeated heating of additive manufacturing result in weak properties,which limits its application.In this study,an in-situ ultrasonic rolling(UR)device was developed to assist the laser directed energy deposition(LDED)process.The microstructural characteristics,as well as the microhardness and wear behavior,were studied for the 316L stainless steel manufactured by in-situ ultrasonic rolling assisted LDED.It is found that austenite,ferrite,and small Si oxides are the main constituents of both the LDED and LDED-UR alloy samples.Under the severe plastic deformation of ultrasonic rolling,the long-branched ferrites by LDED are transformed into the rod-like phases by LDED-UR.Meanwhile,the ferrite is more uniformly distributed in the LDED-UR alloy sample compared with that in LDED alloy sample.Columnar grains with the size of 97.85μm appear in the LDED alloy sample,which is larger than the fully equiaxed grains(22.35μm)of the LDED-UR alloy.The hardness of the LDED-UR alloy sample is about 266.13±13.62 HV_(0.2),which is larger than that of the LDED alloy sample(212.93±12.85 HV_(0.2)).Meanwhile,the wear resistance is also greatly enhanced by applying the assisted in-situ ultrasonic rolling.The achieved high wear resistance can be ascribed to the uniformly distributed hard matter(ferrites)and the impedance of dislocations by high fraction of grain boundaries.Abrasive wear and adhesive wear are identified as the primary wear mechanisms of the studied alloy.Gaining an in-depth understanding of the relationship between wear mechanisms and microstructures offers an effective approach in manufacturing high wear resistant alloys suitable for use in harsh working environments.
基金National Natural Science Foundation of China(U1804124)Key Scientific and Technological Project of Henan Province(202102210014)。
文摘The TZM alloys with different contents of ZrO_(2)were prepared by powder metallurgy and rolling,and the grain size,hardness,and abrasive wear resistance of TZM alloy were studied.The abrasive wear test of TZM alloy was conducted under the conditions of 10,15,and 20 N and abrasive particle sizes of 7,11,18,and 38μm.The results show that the added ZrO_(2)particles in TZM alloy are mainly distributed at the grain boundaries.The grains of TZM alloy containing 1.5wt%ZrO_(2)are significantly refined,and the hardness is increased by 16%.The wear test results show that TZM alloy containing 1.5wt%ZrO_(2)has the lowest mass loss rate and excellent wear resistance under all loads and abrasive sizes,and the wear performance is improved by 12%.The ZrO_(2)with high hardness becomes the main bearer of the load,and as the second-phase,it hinders the abrasive particles from entering the matrix and effectively resists the scratch of the abrasive particles,which is the main reason for the excellent wear resistance.
文摘The morphological description of wear particles in lubricating oil is crucial for wear state monitoring and fault diagnosis in aero-engines.Accurately and comprehensively acquiring three-dimensional(3D)morphological data of these particles has became a key focus in wear debris analysis.Herein,we develop a novel multi-view polarization-sensitive optical coherence tomography(PS-OCT)method to achieve accurate 3D morphology detection and reconstruction of aero-engine lubricant wear particles,effectively resolving occlusion-induced information loss while enabling material-specific characterization.The particle morphology is captured by multi-view imaging,followed by filtering,sharpening,and contour recognition.The method integrates advanced registration algorithms with Poisson reconstruction to generate high-precision 3D models.This approach not only provides accurate 3D morphological reconstruction but also mitigates information loss caused by particle occlusion,ensuring model completeness.Furthermore,by collecting polarization characteristics of typical metals and their oxides in aero-engine lubricants,this work comprehensively characterizes and comparatively analyzes particle polarization properties using Stokes vectors,polarization uniformity,and cumulative phase retardation,and obtains a three-dimensional model containing polarization information.Ultimately,the proposed method enables multidimensional information acquisition for the reliable identification of abrasive particle types.
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 Science and Technology Project of Guangzhou(2023A04J0297)Guangdong Basic and Applied Basic Research Foundation(2024A1515011622)+3 种基金National Natural Science Foundation of China(52301040)GDAS’Project of Science and Technology Development(2023GDASQNRC-0205 and 2022GDASZH-2022010107)Evaluation Project of Guangdong Provincial Key Laboratory(2023B1212060043)Young Elite Scientists Sponsorship Program by CAST(2022QNRC001).
文摘The impact-abrasive wear behavior of high-C martensitic steel was investigated,taking into account varying carbon(C)contents and different tempering temperatures.The evaluation was done through comprehensive microstructural characterization,analysis of worn surface morphology,and measurement of key performance like impact toughness and surface hardening.The findings demonstrate that increasing C content and tempering temperature both has a positive effect on wear resistance,with C content exhibiting a more pronounced influence compared to the tempering temperature.The improved wear resistance of the steel with higher C content and tempering at a higher temperature can be attributed to its enhanced impact toughness.This increase in impact toughness is primarily a result of microstructural refinement and alterations in carbide morphology.Moreover,cyclic impact loading induces surface hardening due to dislocation strengthening within the martensite and the retained austenite,leading to an increase in surface hardness.The combination of surface hardening and excellent impact toughness synergistically contributes to the overall improved wear resistance observed in the experimental steel with higher C content after tempering at a higher temperature.Additionally,the dominant features observed on the worn surface are scratches and substrate delamination,indicative of a wear mechanism of the experimental steels characterized by micro-cutting/ploughing and fatigue wear.
基金supported by the Guangxi Major Science and Technology Project(AB24010120)Young Talent Support Project of Guangzhou Association for Science and Technology(QT-2024-047)+3 种基金Key-Area Research and Development Program of Jiangxi Province(20243BBG71023)GDAS'Project of Science and Technology Development(2023GDASQNRC-0205 and 2024GDASZH-2024010102)Evaluation Project of Guangdong Provincial Key Laboratory(2023B1212060043)Young Elite Scientists Sponsorship Program by CAST(2022QNRC001).
文摘The microstructural evolution,mechanical properties,and wear behavior of medium manganese steels(MMSs)with varying aluminum(Al)contents were investigated.It was observed that the microstructure of MMS transferred from a predominantly martensitic phase(in the Al-free state)to a ferrite/martensite or ferrite/austenite duplex structure with increasing Al content.The hardness of MMS decreased with Al addition,while the impact absorbed energy and yield strength were optimized in 2%Al-containing variant.Frictional wear tests demonstrated that 2 wt.%Al-MMS exhibited superior wear resistance due to the twinning-induced plasticity effect.Conversely,under impact abrasion wear conditions,the Al-free MMS displayed the lowest mass loss,attributing to high surface hardness and remarkable work hardening capacity.These findings indicates that Al content-tailored MMSs can be selectively applied in different wear environments,with 2 wt.%Al-MMS being optimal for static load conditions and the Al-free MMS for dynamic impact abrasion scenarios.
基金Supported by National Key R&D Projects(Grant No.2022YFB3401900)Sichuan Provincial Science and Technology Projects(Grant No.2022JDJQ0019)Fundamental Research Funds for the Central University(Grant No.2682024GF004).
文摘CrN coatings are also employed to protect structural materials in nuclear power plants.It should be noted that the preparation process utilizing physical vapor deposition(PVD)techniques inevitably entails certain defects.Such a phenomenon will affect the protective properties of CrN coatings.In this study,low-energy laser shock peening(LE-LSP)with varying energies was employed for the post-treatment of CrN coatings.The effects of different laser energy LE-LSP treatments on the surface morphology,crystal structure and fretting wear properties of CrN coatings were investigated.The results revealed that the surface of the CrN coatings subjected to LE-LSP underwent significant plastic deformation and displayed a regular texture structure.The surface roughness and Vickers hardness of the CrN coatings exhibit a significant increase.Under a laser energy of 150 mJ,the surface hardness exhibits a maximum increase of 2.35 times.The residual stress of CrN coatings diminishes with the augmentation of laser energy due to the formation of surface cracks.Following LE-LSP treatment,the columnar crystal structure of the CrN coating was disrupted and fragmented into fine grains due to the impact force.As the laser energy augments,the fragmented CrN grains undergo further compaction.During fretting wear,all specimens were in the gross slip regime.The wear mechanism of the CrN coating,120 and 150 mJ specimens are primarily dominated by abrasive wear,and accompanied by oxidative wear.For specimens treated with 30,60 and 90 mJ,the predominant wear mechanisms are mainly peeling and abrasive wear,and accompanied by oxidative wear.Both the wear area and wear volume initially increase and then decrease as the laser energy increases.The 150 mJ specimen exhibited the smallest wear area and wear volume of all tested specimens.The wear volume was reduced by 76.32%when compared to that of the CrN coating.This study complements the existing research on PVD/LSP composite strengthening techniques.Introduces a novel post-treatment methodology for PVD coatings.Provides certain theoretical support for subsequent PVD/LSP composite strengthening.
基金Supported by Beijing Municipal Natural Science Foundation of China(Grant No.8252017)National Natural Science Foundation of China(Grant Nos.51608521,52178375)Beijing Urban Construction Group Co.,Ltd.
文摘To elucidate the wear mechanisms of the scraper in shield tunneling through sandy pebble strata,this study aims to achieve high efficiency and low wear during the tunneling process.We evaluate the operational parameters and tool wear characteristics of a 9-m diameter spoke-type shield machine used on the Beijing Daxing Airport Line.The analysis focuses on the wear values of the scrapers and rippers,wear of the scraper in different wear forms,and scraper wear relative to the position of the rippers obtained from the field.The study yielded the following conclusions.The wear values of scrapers on different spokes vary significantly owing to ripper protection.The wear of the scrapers can be categorized into six types:tooth chipping,local damage of teeth,wear of side teeth,wave-type of wear,wear on intermediate teeth,and flat wear,with the majority exhibiting wear on the side and intermediate teeth.The 0°spoke maintained the initial shape of the scrapers,making it more suitable for tunneling in sandy pebble strata.Based on the differences in the relative positions of the ripper and scraper,a model is proposed to determine the ripper plowing influence area.It was found that this area depends on the geological conditions of the soil;thus,the influence angle of ripper plowing in the considered sandy pebble strata is determined to be between 35°and 50°.The results obtained in this study provide a theoretical reference for optimizing scraper layouts in shield construction,even when operating under varying geological conditions.
基金Supported by National Key Research and Development Program of China(Grant No.2018YFA0707300)Hebei Natural Science Foundation(Grant No.E2023203260)+1 种基金Scientific and Technological Research Projects of Hebei Higher Education Institutions(Grant No.CXY2024009)Central Government Guide Local Science and Technology Development Fund Project(Grant No.216Z1602G)。
文摘The wear of work rolls significantly affects the production efficiency and product quality.However,existing methods for wear assessment fail to effectively quantify work roll surface wear conditions,thereby affecting the quality control of steel strips and maintenance strategies for rolls.To accurately assess the wear conditions of hot-rolling work rolls,this study initially established an apparatus for capturing high-precision roll surfaces images.Subsequently,a quantitative assessment of common surface wear morphologies was conducted,and a hot-rolling work roll surface wear dataset was constructed.The MobileNetV2 convolutional neural network(CNN),augmented by transfer learning,was employed to develop a MobileNetV2-wear detection and classification(WDC)surface wear grading model.A comparison with mainstream CNN models revealed that the MobileNetV2-WDC model achieved high-speed(21.92 ms)and accurate(96.86%)grading with minimal model parameters(2.27 M)and size(27 M),meeting the industrial efficiency and practicality requirements.A visual analysis of the model classification errors was conducted,outlining paths for further optimization.This study provides an efficient and accurate solution for detecting and grading surface wear on hot-rolling work rolls,enhancing product quality and extending the lifespan of rolls.
