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...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
The mechanical properties of ceramic cutting tool materials can be modified by introducing proper content of nanoparticles or whiskers.However,the process of adding whiskers or nanoparticles has the disadvantages of h...The mechanical properties of ceramic cutting tool materials can be modified by introducing proper content of nanoparticles or whiskers.However,the process of adding whiskers or nanoparticles has the disadvantages of high cost and health hazard as well as the agglomeration;although a new in-situ two-step sintering process can solve the above problems to some extent,yet the problems of low conversion ratio of the raw materials and the abnormal grain growth exist in this process.In this paper,an in-situ one-step synthesis technology is proposed,which means the growth of whiskers or nanoparticles and the sintering of the compact can be accomplished by one time in furnace.A kind of Ti（C,N）-based ceramic cutting tool material synergistically toughened by TiB_2 particles and whiskers is fabricated with this new process.The phase compositions,relationships between microstructure and mechanical properties as well as the toughening mechanisms are analyzed by means of X-ray diffraction（XRD）and scanning electron microscopy（SEM）.The composite which is sintered under a pressure of 32 MPa at a temperature of 1700℃in vacuum holding for 60 min can get the optimal mechanical properties.Its flexural strength,fracture toughness and Vickers hardness are 540 MPa,7.81 MPa·m（1/2）and 20.42 GPa,respectively.The composite has relatively high density,and the in-situ synthesized TiB_2 whiskers have good surface integrity,which is beneficial for the improvement of the fracture toughness.It is concluded that the main toughening mechanisms of the present composite are whiskers pulling-out and crack deflection induced by whiskers,crack bridging by whiskers/particles and multi-scale particles synergistically toughening.This study proposes an in-situ one-step synthesis technology which can be well used for fabricating particles and whiskers synergistically toughened ceramic tool materials.展开更多
TiC reinforced titanium composites has been produced with different Al content and C content by XDTM. The results have shown that TiC particles are of two different morphologies f coarse dendritical primary TiC and sh...TiC reinforced titanium composites has been produced with different Al content and C content by XDTM. The results have shown that TiC particles are of two different morphologies f coarse dendritical primary TiC and short bar-shape eutectic TiC. Al content has great effects on the morphology of TiC. With the increasing of Al content, the morphology of primary TiC changes from coarse developed dendrite into short bar-shape or plate--shape TiC with 35%Al. Meanwhile, the structure of the matrix changes from single Ti to Ti and Ti3Al, and to Ti3Al and TiAl. However, the C content has no influence on the microstructure of matrix. When the C content is less than 1.2%, the dendrite TiC disappears and only short bar-shape or plate-shape TiC exists in the composites. In addition, the effect of he3t treatment on the morphology of TiC has also Studied.展开更多
TiC reinforced Ti-6Al-4V matrix composites were fabricated by consumable arc-melting technology utilizing the reaction between titanium and graphite. The phase composition,microstructure and hardness of the TiC/Ti-6Al...TiC reinforced Ti-6Al-4V matrix composites were fabricated by consumable arc-melting technology utilizing the reaction between titanium and graphite. The phase composition,microstructure and hardness of the TiC/Ti-6Al-4V composites were investigated by XRD,SEM and hardness testing equipment,respectively. The results show that the reinforcements are distributed uniformly in the matrix alloy. With the carbon content of the composites increasing from 0.15% to2.0%,the morphology of TiC transforms from particle into short-bar shape or chain-type consisting of featheriness or wheat-shape and finally into dendritic. Simultaneously,the hardness of the composites increases. The formation mechanisms of TiC can be analyzed as follows:the growth of dendritic primary TiC before the peritectic reaction is dominated by the solute concentration gradient,after peritectic reaction,the nucleation and growth of TiC in β-Ti leads to its forming of short-bar shape. The dendritic TiC mainly is distributed in the matrix grain,but the short-bar shape TiC mainly segregates at the grain boundary,especially at the triangular grain boundaries.展开更多
Ti6Al4V alloy‒CoCrMo alloy pair is commonly applied for modular head‒neck interfaces for artificial hip joint.Unfortunately,the fretting corrosion damage at this interface seriously restricts its lifespan.This work st...Ti6Al4V alloy‒CoCrMo alloy pair is commonly applied for modular head‒neck interfaces for artificial hip joint.Unfortunately,the fretting corrosion damage at this interface seriously restricts its lifespan.This work studied the fretting corrosion of Ti6Al4V‒CoCrMo pair in calf serum solution.We established this material pair’s running condition fretting map(RCFM)regarding load and displacement,and revealed the damage mechanism of this material pair in various fretting regimes,namely partial slip regime(PSR),mixed fretting regime(MFR),and gross slip regime(GSR).The damage mechanism of Ti6Al4V alloy was mainly abrasive wear induced by CoCrMo alloy and tribocorrosion.Adhesive wear(material transfer)also existed in MFR.The damage mechanism of CoCrMo alloy was mainly abrasive wear induced by metal oxides and tribocorrosion in GSR and MFR,while no apparent damage in PSR.Furthermore,a dense composite material layer with high hardness was formed in the middle contacting area in GSR,which reduced the corrosion and wear of Ti alloys and exacerbated damage to Co alloys.Finally,the ion concentration maps for Ti and Co ions were constructed,which displayed the transition in the amount of released Ti and Co ions under different displacements and loads.展开更多
为了探索超高分子量聚乙烯 (UHMWPE)与钛基 - Ti N- Ti C系梯度薄膜材料组合作为人工关节置换材料的可能性 ,利用离子注入和等离子体化学气相沉积 (PCVD)方法制备了 Ti6 Al4V- Ti N- Ti C系梯度薄膜材料。通过摩擦系数和 UHMWPE磨损失...为了探索超高分子量聚乙烯 (UHMWPE)与钛基 - Ti N- Ti C系梯度薄膜材料组合作为人工关节置换材料的可能性 ,利用离子注入和等离子体化学气相沉积 (PCVD)方法制备了 Ti6 Al4V- Ti N- Ti C系梯度薄膜材料。通过摩擦系数和 UHMWPE磨损失重的测定和用 SEM对磨损后的 U HMWPE表面形貌分析 ,研究了 U HMWPE与Ti6 Al4V- Ti N- Ti C系梯度薄膜材料摩擦副的生物摩擦磨损特性。研究表明 :在人血清润滑下 ,随配对的梯度薄膜材料表面硬度的增加 ,UHMWPE磨损量减小。与硬度大的 Ti6 Al4V- Ti N- Ti C梯度薄膜材料对磨时 ,UHMWPE的磨损量最小 ,为该摩擦副作为人工关节置换材料提供了依据。还对各摩擦副的 U展开更多
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Supported by National Natural Science Foundation of China(Grant No.51175305)Key Special Project of Numerical Control Machine Tool of China(Grant No.2012ZX04003-051)China Postdoctoral Science Special Foundation(Grant No.2012T50610)
文摘The mechanical properties of ceramic cutting tool materials can be modified by introducing proper content of nanoparticles or whiskers.However,the process of adding whiskers or nanoparticles has the disadvantages of high cost and health hazard as well as the agglomeration;although a new in-situ two-step sintering process can solve the above problems to some extent,yet the problems of low conversion ratio of the raw materials and the abnormal grain growth exist in this process.In this paper,an in-situ one-step synthesis technology is proposed,which means the growth of whiskers or nanoparticles and the sintering of the compact can be accomplished by one time in furnace.A kind of Ti（C,N）-based ceramic cutting tool material synergistically toughened by TiB_2 particles and whiskers is fabricated with this new process.The phase compositions,relationships between microstructure and mechanical properties as well as the toughening mechanisms are analyzed by means of X-ray diffraction（XRD）and scanning electron microscopy（SEM）.The composite which is sintered under a pressure of 32 MPa at a temperature of 1700℃in vacuum holding for 60 min can get the optimal mechanical properties.Its flexural strength,fracture toughness and Vickers hardness are 540 MPa,7.81 MPa·m（1/2）and 20.42 GPa,respectively.The composite has relatively high density,and the in-situ synthesized TiB_2 whiskers have good surface integrity,which is beneficial for the improvement of the fracture toughness.It is concluded that the main toughening mechanisms of the present composite are whiskers pulling-out and crack deflection induced by whiskers,crack bridging by whiskers/particles and multi-scale particles synergistically toughening.This study proposes an in-situ one-step synthesis technology which can be well used for fabricating particles and whiskers synergistically toughened ceramic tool materials.
文摘TiC reinforced titanium composites has been produced with different Al content and C content by XDTM. The results have shown that TiC particles are of two different morphologies f coarse dendritical primary TiC and short bar-shape eutectic TiC. Al content has great effects on the morphology of TiC. With the increasing of Al content, the morphology of primary TiC changes from coarse developed dendrite into short bar-shape or plate--shape TiC with 35%Al. Meanwhile, the structure of the matrix changes from single Ti to Ti and Ti3Al, and to Ti3Al and TiAl. However, the C content has no influence on the microstructure of matrix. When the C content is less than 1.2%, the dendrite TiC disappears and only short bar-shape or plate-shape TiC exists in the composites. In addition, the effect of he3t treatment on the morphology of TiC has also Studied.
基金Project (E200601) supported by the Natural Science Foundation of Heilongjiang ProvinceProject((HEUFP05022) supported by the Foundation of Harbin Engineering University
文摘TiC reinforced Ti-6Al-4V matrix composites were fabricated by consumable arc-melting technology utilizing the reaction between titanium and graphite. The phase composition,microstructure and hardness of the TiC/Ti-6Al-4V composites were investigated by XRD,SEM and hardness testing equipment,respectively. The results show that the reinforcements are distributed uniformly in the matrix alloy. With the carbon content of the composites increasing from 0.15% to2.0%,the morphology of TiC transforms from particle into short-bar shape or chain-type consisting of featheriness or wheat-shape and finally into dendritic. Simultaneously,the hardness of the composites increases. The formation mechanisms of TiC can be analyzed as follows:the growth of dendritic primary TiC before the peritectic reaction is dominated by the solute concentration gradient,after peritectic reaction,the nucleation and growth of TiC in β-Ti leads to its forming of short-bar shape. The dendritic TiC mainly is distributed in the matrix grain,but the short-bar shape TiC mainly segregates at the grain boundary,especially at the triangular grain boundaries.
基金supported by the National Natural Science Foundation of China(Nos.52035012 and 52275215)the Natural Science Foundation of Sichuan Province(No.2022NSFSC1940).
文摘Ti6Al4V alloy‒CoCrMo alloy pair is commonly applied for modular head‒neck interfaces for artificial hip joint.Unfortunately,the fretting corrosion damage at this interface seriously restricts its lifespan.This work studied the fretting corrosion of Ti6Al4V‒CoCrMo pair in calf serum solution.We established this material pair’s running condition fretting map(RCFM)regarding load and displacement,and revealed the damage mechanism of this material pair in various fretting regimes,namely partial slip regime(PSR),mixed fretting regime(MFR),and gross slip regime(GSR).The damage mechanism of Ti6Al4V alloy was mainly abrasive wear induced by CoCrMo alloy and tribocorrosion.Adhesive wear(material transfer)also existed in MFR.The damage mechanism of CoCrMo alloy was mainly abrasive wear induced by metal oxides and tribocorrosion in GSR and MFR,while no apparent damage in PSR.Furthermore,a dense composite material layer with high hardness was formed in the middle contacting area in GSR,which reduced the corrosion and wear of Ti alloys and exacerbated damage to Co alloys.Finally,the ion concentration maps for Ti and Co ions were constructed,which displayed the transition in the amount of released Ti and Co ions under different displacements and loads.
文摘为了探索超高分子量聚乙烯 (UHMWPE)与钛基 - Ti N- Ti C系梯度薄膜材料组合作为人工关节置换材料的可能性 ,利用离子注入和等离子体化学气相沉积 (PCVD)方法制备了 Ti6 Al4V- Ti N- Ti C系梯度薄膜材料。通过摩擦系数和 UHMWPE磨损失重的测定和用 SEM对磨损后的 U HMWPE表面形貌分析 ,研究了 U HMWPE与Ti6 Al4V- Ti N- Ti C系梯度薄膜材料摩擦副的生物摩擦磨损特性。研究表明 :在人血清润滑下 ,随配对的梯度薄膜材料表面硬度的增加 ,UHMWPE磨损量减小。与硬度大的 Ti6 Al4V- Ti N- Ti C梯度薄膜材料对磨时 ,UHMWPE的磨损量最小 ,为该摩擦副作为人工关节置换材料提供了依据。还对各摩擦副的 U
