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Wu Y.-M.,Sichuan University | Xiong J.,Sichuan University | Chen Y.,Chengdu Tool Research Institute | Guo Z.-X.,Sichuan University | Fan H.-Y.,Sichuan University
Sichuan Daxue Xuebao (Gongcheng Kexue Ban)/Journal of Sichuan University (Engineering Science Edition) | Year: 2011

Mo2C has been used in conventional Ti(C, N)-based cermets to improve its wettability between hard phase and binder phase. Recently, some researchers have attempted to develop Ti(C, N)-based cermets free of Mo. To investigate the effect of replacing Mo2C by WC in conventional Ti(C, N)-based cermets, the cutting performance of cermets with the addition of WC and Mo2C was studied, respectively. Wear morphology of cutting tool was observed by SEM, and element distribution of tool surface was analyzed by EDS. The results showed that the cutting tool life of cermets with WC addition was equal to that with Mo2C addition. When the size of the initial WC powder decreased, the cutting tool life could be prolonged, the zonal tangle chip changed to helix chip, and the chip build-up could be reduced. Diffusion wear, oxidation wear accompanied by abrasive wear were considered to be the main wear mechanisms of the cermets.

Luo S.,Southwest Jiaotong University | Zhang X.,Southwest Jiaotong University | Yuan X.,Chengdu Tool Research Institute | Ren P.,Southwest Jiaotong University | Liu H.,Southwest Jiaotong University
Jinshu Rechuli/Heat Treatment of Metals | Year: 2015

Fretting wear behavior of 690 alloy and TiN/TiSiN multiplayer films deposited by Plasma Chemical Vapor Deposition (PCVD) on substrate at elevated temperature was investigated by using the hydraulic fretting test machine with a high precision. The results indicate that there are no oxides observed in TiN/TiSiN multiplayer films XRD patterns at test temperatures (25, 200, 300℃), the hardness and critical load of TiN/TiSiN multiplayer films are 2318 HV0.05 and 57 N respectively. The friction coefficient and wear volume of 690 alloy at 200℃ is higher than that at room temperature and 300℃. The friction coefficient evolution of TiN/TiSiN multiplayer films reaches the maximum at 200℃, and minimum at 25℃. The effect of temperature on wear volume for TiN/TiSiN multiplayer films is not remarkable. Under the same conditions, the friction coefficient and wear volume of TiN/TiSiN multiplayer films are smaller than that of 690 alloy, and TiN/TiSiN multiplayer films can reduce the fretting damage of substrate effectively. The fretting mechanism of 690 alloy is abrasive wear and delamination at room temperature; while the fretting mechanism is a combination of abrasive wear, oxidization wear and delamination at 200℃; and the fretting mechanism is abrasive and oxidization wear at 300℃. The fretting mechanism of TiN/TiSiN multiplayer films is delamination under different test temperature conditions. ©, 2015, Chinese Mechanical Engineering Society of Heat Treatment. All right reserved.

Xie M.-Q.,Chengdu Tool Research Institute | Li H.-Y.,Chengdu Tool Research Institute | Wang H.,Chengdu Tool Research Institute | Dai Y.-Q.,Chengdu Tool Research Institute | Liu L.,Tianjin Thermtreatment Materials Co.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2010

Microstructure, phases structure and distribution for nitrogen, carbon and oxygen elements on45,40Cr and 20 steel after deep-layer QPQ treatment were studied by metallographic microscope, SEM and XRD. The results show that the layer after deep-layer QPQ treatment is mainly made up with the phases of Fe304 ,ε,γ and a little of α Fe 304 is in the surface porosity,which has a high oxygen concentration. The compound layer is mainly made up with the phases of ε,γ and a little of ot,which has a even nitrogen distribution. The medium-layer is mainly made up with the phases of γ and α,which has a high nitrogen and carbon concentration. The results of the spectrum show that the nitrogen decreases obviously and the oxygen increases obviously in the porosity, which is a reliable evidence to prove the porosity-hole theory that the porosity is made up of the hole which forms by the molecularized of the nitrogen atoms.

Wang J.,Chongqing Academy of Science and Technology | Jiang X.-Q.,Chongqing Academy of Science and Technology | Yang Q.-K.,Chengdu Tool Research Institute
Gongneng Cailiao/Journal of Functional Materials | Year: 2014

Optimization of binder's composition for WC-Ni cemented carbide was studied to improve its mechanics properties. With constant content of binder, some Ni powder was replaced by equal quantitative Fe powder. The microstructure and mechanics properties of cemented carbide with different binder were studied. The results indicated that the growth of WC grain was inhibitted by a small addition of Fe powder. The bending strength of sintered body increased firstly and then descended, and the hardness descended with the increment of Fe powder. Mechanics properties of WC-7%Ni-1%Fe were as good as WC-Ni cemented carbide doped with Cr or Mo. ©, 2014, Journal of Functional Materials. All right reserved.

Wu S.-X.,Chengdu Tool Research Institute | Xie M.-Q.,Chengdu Tool Research Institute | Wang H.,Chengdu Tool Research Institute | Hu J.-F.,Chengdu Tool Research Institute | Li H.-Y.,Chengdu Tool Research Institute
Jinshu Rechuli/Heat Treatment of Metals | Year: 2011

Effects of the oxidation layer, compound layer, diffusion layer and loose layer and procedures in QPQ treatment and adding sealants on corrosion resistance of steel parts were investigated through salt spray tests. The results show that the diffusion layer basically does not have anti-corrosion. Corrosion resistance of the oxidation layer is low and that of the compound layer is much better. Too thick loose layer will reduce corrosion resistance of the compound layer, and it's better to try to reduce the thickness of the loose layer. Permeability nitrogen-oxidation layer formed compound nitriding layer has quite high resistance to corrosion. Effect of nitrogen time on corrosion resistance has a best time peak. Polishing and second oxidation will effectively improve corrosion resistance, and sealant can dramatically improve corrosion resistance.

Fu C.-M.,Northeastern University China | Liu C.-S.,Northeastern University China | Shen F.-M.,Northeastern University China | Chen S.-Y.,Chengdu Tool Research Institute
Cailiao Kexue yu Gongyi/Material Science and Technology | Year: 2011

QPQ salt bath composite process, which is a new modification technology of surface hardening of metal salt bath, was used to 3Cr2W8V steel, and with the help of OM, SEM, microhardness tester, X-ray diffraction, high-temperature friction and wear tester and electrochemical workstation, the microstructure, chemical composition, microhardness, phase, wear resistance and corrosion resistance of QPQ layer were analyzed. The results show that QPQ surface layer is flat, and when the salt bath nitrocarburizing time is certain, with the increasing of the nitrocarburizing salt bath temperature, the first appeared phase is Fe 3N, followed by the emergence of Fe 4N and Fe 3O 4 phases, and finally there is Fe 2N phase. The surface microhardness of specimens treated by QPQ is 600~1400 HV 0.1, and the matrix hardness is 520 HV 0.1. The smallest wear loss of samples by QPQ treatment is half of that of matrix and the friction coefficient is the minimum, when the nitrocarburizing temperature is 580°C, and the nitrocarburizing time is 1 h. In the certain oxidation temperature of molten salt bath, the corrosion potential and the corrosion resistance increase gradually with the extended oxidation time. When the molten salt oxidation temperature is set to 380°C and the oxidation time is 120 minutes, the corrosion potential of QPQ treated sample is the highest, and the corrosion resistance is the best.

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