The influence of yttrium addition on microstructure and wearability of WC78 TiC14 Co8 cemented carbide has been studied It is shown that the wearability of the carbide tool is significantly improved by adding trac...The influence of yttrium addition on microstructure and wearability of WC78 TiC14 Co8 cemented carbide has been studied It is shown that the wearability of the carbide tool is significantly improved by adding trace amount of yttrium and the optimal adding amount is about 0 27%(wt)(in binder) Experimental results indicate that owing to adding yttrium, in as sintered cemented carbides the sizes of carbide grains and Co rich binder regions are reduced and their size homogeneity is improved, while in the binder, both dissolved contents of tungsten and titanium and volume proportion of the ductile α Co phase with f c c lattice are increased Therefore, the strength toughness of the binder and the cemented carbide which consists of the carbides and the binder are apparently enhanced Besides, it is found that many Y 2WO 6 particles appear along the WC/WC or WC/Co rich phase interfaces in as sintered carbide alloy with yttrium addition until 4 5%(wt), showing that during liquid phase sintering process of the alloys the segregation of yttrium atoms and Y 2WO 6 forming reaction might take place on the carbide particles/liquid binder interfaces, reducing the oxide films on the surface of WC particles and strengthening the cohesion of WC particles with Co rich binder展开更多
Phase analysis for the coated surface with B 4C and Y 2O 3 of cemented carbide WC-20Co in vacuum-heating was carried out by high-temperature X-ray diffraction from ambient temperature to 1300 ℃. The results show t...Phase analysis for the coated surface with B 4C and Y 2O 3 of cemented carbide WC-20Co in vacuum-heating was carried out by high-temperature X-ray diffraction from ambient temperature to 1300 ℃. The results show that, the high-concentration active boron atoms are released from the boron-supply agent B 4C located on the alloy surface and diffused into the γ-phase, leading to forming the three-element boron-bearing compound W 2Co 21B 6 beside forming boron-bearing compounds on the blank surface. By contrast with boronising only, the element yttrium in boronization broadens the boronising temperature range during vacuum-sintering, catalyzes the decarbonisation decomposition of B 4C and promotes diffusion of active boron atoms into the bulk of WC-Co.展开更多
A method, doping WC with La(NO 3) 3, of producing cemented carbide with rare earth was introduced. The effects of lanthanum on the mechanical properties and microstructure of WC 9(Co 75%Ni) cemented carbide were studi...A method, doping WC with La(NO 3) 3, of producing cemented carbide with rare earth was introduced. The effects of lanthanum on the mechanical properties and microstructure of WC 9(Co 75%Ni) cemented carbide were studied and a rock drilling experiment was carried out.The experimental results show that both transverse rupture strength (TRS) and hardness of WC 9(Co 75%Ni) rare earth cemented carbides can match that of WC 9Co cemented carbide, when La 2O 3 / (Co+Ni) ratio is 0.3%, the abnormal growth of WC grain in the cemented carbide can be restrained effectively, the homogeneity of grain size in microstructure and the wear resistance are improved, which can be matchable to that of WC 9Co cemented carbide for mining.展开更多
The existence form and distribution of new rare earth additions in WC-Co,WC-TiC-Co.Cemented carbide and its actions of purification,modificaiton,solid solution strengthening and restraining phase transformation have b...The existence form and distribution of new rare earth additions in WC-Co,WC-TiC-Co.Cemented carbide and its actions of purification,modificaiton,solid solution strengthening and restraining phase transformation have been investigated.The results have been used to elucidate property im- provement of the alloys.展开更多
WC cemented carbide suffers severe wear in water environments. A novel carbon-based film could be a feasible way to overcome this drawback. In this study, a rare earth Ce-modified(Ti,Ce)/a-C:H carbon-based film is ...WC cemented carbide suffers severe wear in water environments. A novel carbon-based film could be a feasible way to overcome this drawback. In this study, a rare earth Ce-modified(Ti,Ce)/a-C:H carbon-based film is successfully prepared on WC cemented carbide using a DC reactive magnetron sputtering process. The microstructure, mechanical properties,and tribological behavior of the as-prepared carbon-based film are systematically investigated. The results show that the doping Ti forms Ti C nanocrystallites that are uniformly dispersed in the amorphous carbon matrix, whereas the doping Ce forms CeO2 that exists with the amorphous phase in the co-doped(Ti,Ce)/a-C:H carbon-based film. The mechanical properties of this(Ti,Ce)/a-C:H film exhibit remarkable improvements, which could suggest higher hardness and elastic modulus as well as better adhesive strength compared to solitary Ti-doped Ti/a-C:H film. In particular, the as-prepared(Ti,Ce)/a-C:H film presents a relatively low friction coefficient and wear rate in both ambient air and deionized water,indicating that(Ti,Ce)/a-C:H film could feasibly improve the tribological performance of WC cemented carbide in a water environment.展开更多
The morphology,structure and distribution of the rare earth compounds in the YG8R.YT5R and YT14R cemented carbides with additions of trace light rare earths were studied with an analytical electron microscope. The par...The morphology,structure and distribution of the rare earth compounds in the YG8R.YT5R and YT14R cemented carbides with additions of trace light rare earths were studied with an analytical electron microscope. The particles of the rare earth compounds in these alloys are all spherical and distribute at interfaces between the Co-cement phase and WC hard phase or(TiW)C solid solution,and in the(TiW)C solid solution.In the YG8R and YTI4R alloys,the rare earth compound is RE_2O_3 with a bcc structure,while in the YT5R alloy. the rare earth compound is RE_2O_2S with a hcp structure.展开更多
Three observation methods were used to investigate the existing form and the behavior of rare earth during the sintering process of high activity mischmetal (RE, with lanthanum and cerium) doped WC-8%Co-0.048%RE(ma...Three observation methods were used to investigate the existing form and the behavior of rare earth during the sintering process of high activity mischmetal (RE, with lanthanum and cerium) doped WC-8%Co-0.048%RE(mass fraction) alloy with low carbon-containing level by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS), considering the fact that the addition amount of rare earth in the alloy is very minute. The directional migration process and mechanism of cerium were discussed. First, the sinter skin (surface) is observed. oxide on the sinter skin, and lanthanum in these cerium observed, and lanthanum containing phase/micro-zone in It is shown that there exists a dispersedly distributed cerium containing enrichment positions is very minute. Secondly, the polished section is the alloy is identified. Finally, based on the fact that the fracture of cemented carbide is resulted from the heterogeneous phase or other defects within the microstructure, the fracture surface is observed and cerium containing phase/micro-zone in the fracture source approximately 260 μm from the surface is identified. These combined observations reveal adequately the fact that lanthanum and cerium get separated and cerium predominantly migrates towards the surface during the sintering process.展开更多
Ultrafine tungsten carbide and fine cobalt as well as nano yttrium oxide powders were used as the raw materials. The effects of hot-press below the eutectic temperature and conventional liquid phase sintering on the s...Ultrafine tungsten carbide and fine cobalt as well as nano yttrium oxide powders were used as the raw materials. The effects of hot-press below the eutectic temperature and conventional liquid phase sintering on the structures and properties of WC-20Co-1Y2O3 cemented carbide were studied. It is shown that hot-pressed alloy has the character of isotropic properties and microstructure with homogeneous and ultrafine WC grains. However, the ultrafine and fully-densified structure is developed at the cost of the presence of large amount of cobalt-lake (unevenly distributed binder phase), and thus lower strength. Yttrium oxide in the alloy cannot play the role of grain growth inhibitor fully when cemented carbide with high content of cobalt and ultrafine raw materials is sintered at high liquid phase sintering temperature. Peculiar platelet-enhanced bi-model structure is formed in WC-20Co-1Y2O3 cemented carbide by conventional liquid phase sintering, which points out that yttrium oxide in the alloy facilitates the formation of plate-like WC grain.展开更多
In order to reduce or eliminate the adverse effects of calcium impurity,the interaction of Ca and rare earth Y co-doping on the preparation of WC-Co cemented carbides was investigated.X-ray diffraction,scanning electr...In order to reduce or eliminate the adverse effects of calcium impurity,the interaction of Ca and rare earth Y co-doping on the preparation of WC-Co cemented carbides was investigated.X-ray diffraction,scanning electron microscopy and transmission electron microscopy were employed to analyze the phase compositions,particle sizes and morphologies of them,respectively.The results show that the second type of"yttrium barrier effect"is observed and the adverse influence of Ca-rich phase on tungsten powder can be eliminated by it.The flexural strength and fracture toughness of YG6-0.01%Ca+0.09%Y alloy are 2199.5 MPa and 11.49 MPa·m^(1/2),showing improvement of 6.5% and 2.7% compared to YG6 alloy,respectively.The evolutions of Ca-rich phase and Y-rich phase at the every alloy preparation stage of WO_(3),W,WC and cemented carbides are obtained.Furthermore,the strengthening mechanism of WC-Co cemented carbide with co-addition of Ca and Y is proposed.展开更多
The effects of rare earth (RE) elements on properties and microstructure of WC-14TiC-8Co cemented carbide have been investigated. By adding RE, the characteristics such as bending strength and impact-resistance were g...The effects of rare earth (RE) elements on properties and microstructure of WC-14TiC-8Co cemented carbide have been investigated. By adding RE, the characteristics such as bending strength and impact-resistance were greatly improved. The existence form and distribution of RE in cemented carbide have also been studied by means of SEM and TEM. The results. have been used to elucidate the strengthening mechanism of RE in WC-14TiC-8Co alloy.展开更多
The properties of the cemented carbides with RE-addition were improved in our research.there is a 10% increase of the transverse rupture strength(T.R.S) of YT14RE as compared with that of YT14.The hardness and the den...The properties of the cemented carbides with RE-addition were improved in our research.there is a 10% increase of the transverse rupture strength(T.R.S) of YT14RE as compared with that of YT14.The hardness and the density of YT14RE are higher than that of YT14.The cast steel was cut at a speed of 140 m/min by cutting tcols which made from YT14RE and YT14.The wear resistant of the former is 1.5 time of the latter.The samples of YT14RE and YT14 were ground and polished(the content of the RE elements is less than 0.10 wt%).This paper studied the effect of adding rare earth element on cemented carbide by digital image.展开更多
Effects of Cr3C2,VC and La2O3 additions on the WC grain morphology,hardness and toughness of WC-10Co alloys were investigated.To intensify the grain growth driving force,nano W and nano C,instead of the conventionally...Effects of Cr3C2,VC and La2O3 additions on the WC grain morphology,hardness and toughness of WC-10Co alloys were investigated.To intensify the grain growth driving force,nano W and nano C,instead of the conventionally used WC,were used as the starting materials.To obtain a three-dimensional WC grain morphology,the natural sinter skins of the alloys were observed directly by scanning electron microscopy.It is shown that the additions have a strong ability in regulating the WC grain morphological and grain size distribution characteristics and the combinations of hardness and toughness.Due to the formation of regular and homogeneous triangular platelet WC grains,WC-10Co-0.6Cr3C2-0.06La2O3 alloy shows an excellent combination of hardness and toughness.The morphological regulation mechanism,the relationship between the WC grain morphology and the properties were discussed.展开更多
The research of rare earth elements (RE), added into cemented carbide tools, is one of the recent developments of new types of tool materials in China. Systematic experiments about RE carbides YG8R. (K30), YT14R (P20)...The research of rare earth elements (RE), added into cemented carbide tools, is one of the recent developments of new types of tool materials in China. Systematic experiments about RE carbides YG8R. (K30), YT14R (P20) and, YW1R (M10) were made to study on the cutting performance in comparison with non-RE carbides YG8, YT14 and YW1. The cutting experiments were as follows: tool life, cutting force, tool-chip friction coefficient and interrupted machining. The action of RE on the carbide materials and the cutting mechanism of the RE carbide tools in the cutting process were verified with the aid of SEM and energy spectrum analysis. Experimental results show that the RE carbide tools have a good overall performance.展开更多
文摘The influence of yttrium addition on microstructure and wearability of WC78 TiC14 Co8 cemented carbide has been studied It is shown that the wearability of the carbide tool is significantly improved by adding trace amount of yttrium and the optimal adding amount is about 0 27%(wt)(in binder) Experimental results indicate that owing to adding yttrium, in as sintered cemented carbides the sizes of carbide grains and Co rich binder regions are reduced and their size homogeneity is improved, while in the binder, both dissolved contents of tungsten and titanium and volume proportion of the ductile α Co phase with f c c lattice are increased Therefore, the strength toughness of the binder and the cemented carbide which consists of the carbides and the binder are apparently enhanced Besides, it is found that many Y 2WO 6 particles appear along the WC/WC or WC/Co rich phase interfaces in as sintered carbide alloy with yttrium addition until 4 5%(wt), showing that during liquid phase sintering process of the alloys the segregation of yttrium atoms and Y 2WO 6 forming reaction might take place on the carbide particles/liquid binder interfaces, reducing the oxide films on the surface of WC particles and strengthening the cohesion of WC particles with Co rich binder
文摘Phase analysis for the coated surface with B 4C and Y 2O 3 of cemented carbide WC-20Co in vacuum-heating was carried out by high-temperature X-ray diffraction from ambient temperature to 1300 ℃. The results show that, the high-concentration active boron atoms are released from the boron-supply agent B 4C located on the alloy surface and diffused into the γ-phase, leading to forming the three-element boron-bearing compound W 2Co 21B 6 beside forming boron-bearing compounds on the blank surface. By contrast with boronising only, the element yttrium in boronization broadens the boronising temperature range during vacuum-sintering, catalyzes the decarbonisation decomposition of B 4C and promotes diffusion of active boron atoms into the bulk of WC-Co.
文摘A method, doping WC with La(NO 3) 3, of producing cemented carbide with rare earth was introduced. The effects of lanthanum on the mechanical properties and microstructure of WC 9(Co 75%Ni) cemented carbide were studied and a rock drilling experiment was carried out.The experimental results show that both transverse rupture strength (TRS) and hardness of WC 9(Co 75%Ni) rare earth cemented carbides can match that of WC 9Co cemented carbide, when La 2O 3 / (Co+Ni) ratio is 0.3%, the abnormal growth of WC grain in the cemented carbide can be restrained effectively, the homogeneity of grain size in microstructure and the wear resistance are improved, which can be matchable to that of WC 9Co cemented carbide for mining.
文摘The existence form and distribution of new rare earth additions in WC-Co,WC-TiC-Co.Cemented carbide and its actions of purification,modificaiton,solid solution strengthening and restraining phase transformation have been investigated.The results have been used to elucidate property im- provement of the alloys.
基金supported by the National Natural Science Foundation of China(Grant Nos.51302116 and 51365016)the Program for Excellent Young Talents,Jiangxi University of Science and Technology,China
文摘WC cemented carbide suffers severe wear in water environments. A novel carbon-based film could be a feasible way to overcome this drawback. In this study, a rare earth Ce-modified(Ti,Ce)/a-C:H carbon-based film is successfully prepared on WC cemented carbide using a DC reactive magnetron sputtering process. The microstructure, mechanical properties,and tribological behavior of the as-prepared carbon-based film are systematically investigated. The results show that the doping Ti forms Ti C nanocrystallites that are uniformly dispersed in the amorphous carbon matrix, whereas the doping Ce forms CeO2 that exists with the amorphous phase in the co-doped(Ti,Ce)/a-C:H carbon-based film. The mechanical properties of this(Ti,Ce)/a-C:H film exhibit remarkable improvements, which could suggest higher hardness and elastic modulus as well as better adhesive strength compared to solitary Ti-doped Ti/a-C:H film. In particular, the as-prepared(Ti,Ce)/a-C:H film presents a relatively low friction coefficient and wear rate in both ambient air and deionized water,indicating that(Ti,Ce)/a-C:H film could feasibly improve the tribological performance of WC cemented carbide in a water environment.
文摘The morphology,structure and distribution of the rare earth compounds in the YG8R.YT5R and YT14R cemented carbides with additions of trace light rare earths were studied with an analytical electron microscope. The particles of the rare earth compounds in these alloys are all spherical and distribute at interfaces between the Co-cement phase and WC hard phase or(TiW)C solid solution,and in the(TiW)C solid solution.In the YG8R and YTI4R alloys,the rare earth compound is RE_2O_3 with a bcc structure,while in the YT5R alloy. the rare earth compound is RE_2O_2S with a hcp structure.
基金Project(50574104) supported by the National Natural Science Foundation of China
文摘Three observation methods were used to investigate the existing form and the behavior of rare earth during the sintering process of high activity mischmetal (RE, with lanthanum and cerium) doped WC-8%Co-0.048%RE(mass fraction) alloy with low carbon-containing level by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS), considering the fact that the addition amount of rare earth in the alloy is very minute. The directional migration process and mechanism of cerium were discussed. First, the sinter skin (surface) is observed. oxide on the sinter skin, and lanthanum in these cerium observed, and lanthanum containing phase/micro-zone in It is shown that there exists a dispersedly distributed cerium containing enrichment positions is very minute. Secondly, the polished section is the alloy is identified. Finally, based on the fact that the fracture of cemented carbide is resulted from the heterogeneous phase or other defects within the microstructure, the fracture surface is observed and cerium containing phase/micro-zone in the fracture source approximately 260 μm from the surface is identified. These combined observations reveal adequately the fact that lanthanum and cerium get separated and cerium predominantly migrates towards the surface during the sintering process.
文摘Ultrafine tungsten carbide and fine cobalt as well as nano yttrium oxide powders were used as the raw materials. The effects of hot-press below the eutectic temperature and conventional liquid phase sintering on the structures and properties of WC-20Co-1Y2O3 cemented carbide were studied. It is shown that hot-pressed alloy has the character of isotropic properties and microstructure with homogeneous and ultrafine WC grains. However, the ultrafine and fully-densified structure is developed at the cost of the presence of large amount of cobalt-lake (unevenly distributed binder phase), and thus lower strength. Yttrium oxide in the alloy cannot play the role of grain growth inhibitor fully when cemented carbide with high content of cobalt and ultrafine raw materials is sintered at high liquid phase sintering temperature. Peculiar platelet-enhanced bi-model structure is formed in WC-20Co-1Y2O3 cemented carbide by conventional liquid phase sintering, which points out that yttrium oxide in the alloy facilitates the formation of plate-like WC grain.
基金Project supported by the National Natural Science Foundation of China(51564036,52164043)the Natural Science Foundation of Jiangxi Province(2002BAB204013)the Key Research and Development Program of Science and Technology Deprtment of Jiangxi Province(20192BBE50034)。
文摘In order to reduce or eliminate the adverse effects of calcium impurity,the interaction of Ca and rare earth Y co-doping on the preparation of WC-Co cemented carbides was investigated.X-ray diffraction,scanning electron microscopy and transmission electron microscopy were employed to analyze the phase compositions,particle sizes and morphologies of them,respectively.The results show that the second type of"yttrium barrier effect"is observed and the adverse influence of Ca-rich phase on tungsten powder can be eliminated by it.The flexural strength and fracture toughness of YG6-0.01%Ca+0.09%Y alloy are 2199.5 MPa and 11.49 MPa·m^(1/2),showing improvement of 6.5% and 2.7% compared to YG6 alloy,respectively.The evolutions of Ca-rich phase and Y-rich phase at the every alloy preparation stage of WO_(3),W,WC and cemented carbides are obtained.Furthermore,the strengthening mechanism of WC-Co cemented carbide with co-addition of Ca and Y is proposed.
文摘The effects of rare earth (RE) elements on properties and microstructure of WC-14TiC-8Co cemented carbide have been investigated. By adding RE, the characteristics such as bending strength and impact-resistance were greatly improved. The existence form and distribution of RE in cemented carbide have also been studied by means of SEM and TEM. The results. have been used to elucidate the strengthening mechanism of RE in WC-14TiC-8Co alloy.
文摘The properties of the cemented carbides with RE-addition were improved in our research.there is a 10% increase of the transverse rupture strength(T.R.S) of YT14RE as compared with that of YT14.The hardness and the density of YT14RE are higher than that of YT14.The cast steel was cut at a speed of 140 m/min by cutting tcols which made from YT14RE and YT14.The wear resistant of the former is 1.5 time of the latter.The samples of YT14RE and YT14 were ground and polished(the content of the RE elements is less than 0.10 wt%).This paper studied the effect of adding rare earth element on cemented carbide by digital image.
基金Project (51074189) supported by the National Natural Science Foundation of ChinaProject (20100162110001) supported by Research Fund for the Doctoral Program of Higher Education of ChinaProject (2011BAE09B02) supported by the National Science & Technology Special Foundation of China
文摘Effects of Cr3C2,VC and La2O3 additions on the WC grain morphology,hardness and toughness of WC-10Co alloys were investigated.To intensify the grain growth driving force,nano W and nano C,instead of the conventionally used WC,were used as the starting materials.To obtain a three-dimensional WC grain morphology,the natural sinter skins of the alloys were observed directly by scanning electron microscopy.It is shown that the additions have a strong ability in regulating the WC grain morphological and grain size distribution characteristics and the combinations of hardness and toughness.Due to the formation of regular and homogeneous triangular platelet WC grains,WC-10Co-0.6Cr3C2-0.06La2O3 alloy shows an excellent combination of hardness and toughness.The morphological regulation mechanism,the relationship between the WC grain morphology and the properties were discussed.
文摘The research of rare earth elements (RE), added into cemented carbide tools, is one of the recent developments of new types of tool materials in China. Systematic experiments about RE carbides YG8R. (K30), YT14R (P20) and, YW1R (M10) were made to study on the cutting performance in comparison with non-RE carbides YG8, YT14 and YW1. The cutting experiments were as follows: tool life, cutting force, tool-chip friction coefficient and interrupted machining. The action of RE on the carbide materials and the cutting mechanism of the RE carbide tools in the cutting process were verified with the aid of SEM and energy spectrum analysis. Experimental results show that the RE carbide tools have a good overall performance.