Cr_(2)O_(3)was used as grain inhibitor in Ti(C,N)-based cermets with vacuum sintering.The microstructure and mechanical and tribological properties of cermets with Cr_(2)O_(3)and Cr_(3)C_(2)were investigated.The resul...Cr_(2)O_(3)was used as grain inhibitor in Ti(C,N)-based cermets with vacuum sintering.The microstructure and mechanical and tribological properties of cermets with Cr_(2)O_(3)and Cr_(3)C_(2)were investigated.The results show that adding Cr_(2)O_(3)promotes a gray core/gray rim structure formation and finer size of Ti(C,N)hard phase.Compared with the cermet with an equal Cr_(3)C_(2)addition,the cermet with 0.6 wt.%Cr_(2)O_(3)exhibits 16.5%higher transverse rupture strength.This enhancement is likely due to the smaller lattice misfit at the core/rim interface and more uniform Cr distribution in the binder.Additionally,at room temperature(25℃)and 800℃,Cr_(2)O_(3)-containing cermets demonstrate lower coefficients of friction and volume wear ratios than Cr_(3)C_(2)-containing cermets,with the wear ratio difference reaching an order of magnitude.Scanning electron microscopy and X-ray photoelectron spectroscopy results further confirm more oxidation wear in Cr_(2)O_(3)-containing cermets than in Cr_(3)C_(2)-containing cermets.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
Effects of VC/Cr3C2 on the microstructure and mechanical properties of Ti（C,N）-based cermets were studied. The microstructure was investigated by means of optical microscopy, X-ray diffractometry as well as scanning...Effects of VC/Cr3C2 on the microstructure and mechanical properties of Ti（C,N）-based cermets were studied. The microstructure was investigated by means of optical microscopy, X-ray diffractometry as well as scanning electron microscopy in combination with energy dispersive spectrometry. Mechanical properties, such as transverse rupture strength, hardness and fracture toughness, were measured. The results show that there are black core-grey rim structure and white core-grey rim structure in the microstructure. The grains become fine due to the VC/Cr3C2, and the grains of cermet added with 0.75VC/0.25Cr3C2 are refined most remarkably. The black core becomes finer with the increase of VC addition and rim phase becomes thicker with the decrease of Cr3C2 addition. The porosity increases with the increase of VC addition in VC/Cr3C2. Compared with the cermet free of VC/Cr3C2, the transverse rupture strength and hardness of cermets with VC/Cr3C2 are both improved, and the maximum values are both found for the cermet with 0.25VC/0.75Cr3C2. The fracture toughness can be effectively promoted by adding VC/Cr3C2 with an appropriate ratio of VC to Cr3C2, and the maximum value is found for the cermet with 0.5VC/0.5Cr3C2.展开更多
基金Natural Science Foundation of Ningxia,China(No.2023AAC03284)Fundamental Research Funds for the Central Universities Research Project of North Minzu University,China(No.2022XYZCL04)+1 种基金Project of Key Laboratory of Powders and Advanced CeramicsCo-founded by Ningxia and the State Ethnic Affairs Commission,China(No.2103)。
文摘Cr_(2)O_(3)was used as grain inhibitor in Ti(C,N)-based cermets with vacuum sintering.The microstructure and mechanical and tribological properties of cermets with Cr_(2)O_(3)and Cr_(3)C_(2)were investigated.The results show that adding Cr_(2)O_(3)promotes a gray core/gray rim structure formation and finer size of Ti(C,N)hard phase.Compared with the cermet with an equal Cr_(3)C_(2)addition,the cermet with 0.6 wt.%Cr_(2)O_(3)exhibits 16.5%higher transverse rupture strength.This enhancement is likely due to the smaller lattice misfit at the core/rim interface and more uniform Cr distribution in the binder.Additionally,at room temperature(25℃)and 800℃,Cr_(2)O_(3)-containing cermets demonstrate lower coefficients of friction and volume wear ratios than Cr_(3)C_(2)-containing cermets,with the wear ratio difference reaching an order of magnitude.Scanning electron microscopy and X-ray photoelectron spectroscopy results further confirm more oxidation wear in Cr_(2)O_(3)-containing cermets than in Cr_(3)C_(2)-containing cermets.
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 (090414185) supported by the Natural Science Foundation of Anhui Province, China
文摘Effects of VC/Cr3C2 on the microstructure and mechanical properties of Ti（C,N）-based cermets were studied. The microstructure was investigated by means of optical microscopy, X-ray diffractometry as well as scanning electron microscopy in combination with energy dispersive spectrometry. Mechanical properties, such as transverse rupture strength, hardness and fracture toughness, were measured. The results show that there are black core-grey rim structure and white core-grey rim structure in the microstructure. The grains become fine due to the VC/Cr3C2, and the grains of cermet added with 0.75VC/0.25Cr3C2 are refined most remarkably. The black core becomes finer with the increase of VC addition and rim phase becomes thicker with the decrease of Cr3C2 addition. The porosity increases with the increase of VC addition in VC/Cr3C2. Compared with the cermet free of VC/Cr3C2, the transverse rupture strength and hardness of cermets with VC/Cr3C2 are both improved, and the maximum values are both found for the cermet with 0.25VC/0.75Cr3C2. The fracture toughness can be effectively promoted by adding VC/Cr3C2 with an appropriate ratio of VC to Cr3C2, and the maximum value is found for the cermet with 0.5VC/0.5Cr3C2.
