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Effects of gradient structure on the microstructures and properties of coated cemented carbides

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Journal of University of Science and Technology Beijing 2006年第4期13卷 363-367页

作者： Li Chen Enxi Wu Fei Yin Jia Li State Key Laboratory for Powder Metallurgy Central South University Changsha 410083 China zhuzhou cemented carbide cutting tools co. ltd. Zhuzhou 412007 China

The effects of gradient structure on the microstructure and properties of coated cemented carbides were researched with optical microscopy （OM）, scanning electron microscopy （SEM）, strength measurements, and cutting tests. It shows that vacuum sintering of WC-Ti（C, N）-TaC-co cemented carbides results in the formation of a surface ductile zone. The ductile zone prevents crack propagation and leads to the increase of transverse rupture strength of the substrate. The impact resistance of coated gradient inserts was obviously improved on the basis of maintaining resistance to abrasion and the forming mechanism of the gradient structure was also analyzed.

关键词： cemented carbide chemical vapor deposition (CVD) coating gradient structure

Effect of Radial Depth on Vibration and Surface Roughness During Face Milling of Austenitic Stainless Steel

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Transactions of Tianjin University 2011年第5期17卷 336-339页

作者：申阳陈永洁张俐方海涛庞佳刘敏王社权马晓魁张京刘志林 School of Mechanical Science and Engineering Huazhong University of Science and Technology zhuzhou cemented carbide cutting tools co. Ltd

This paper studies the influence of radial depth on vibration, chip formation and surface roughness during face milling of AISl3O4 austenitic stainless steel with indexable cemented carbide milling cutters. The amplitude of vibration acceleration increased with the increasing radial depth up to 80 mm. And the domain vibration frequency varied with the radial depth. In this paper, three types of chips were found： C shape, long shape and spiral shape. The minimum surface roughness value occurred when the radial depth equalled 40 mm in the experiment. Irregular changes of chip curl radius and chip thickness could be attributed to different numbers of alternately engaged teeth when the feed and speed were fixed. Surface roughness is related to forced vibration and chip formation. Radial depth with different numbers of alternately engaged teeth could significantly influence the forced vibration, chip formation, and surface roughness.

关键词： austenitic stainless steel face milling radial depth vibration surface roughness chip formation

Microstructure, mechanical properties, and milling performance of arc-PVD AlTiN–Cu and AlTiN/AlTiN–Cu coatings

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Journal of Central South University 2018年第3期25卷 506-515页

作者： CHEN Hao CHEN Kang-hua XU Yin-chao PAN Chen-xi YI Ji-yong ZHU Chang-jun State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China zhuzhou cemented carbide cutting tools co.ltd. Zhuzhou 412000China

AlTiN,AlTiN–Cu and AlTiN/AlTiN–Cu coatings were prepared on WC–6%co substrates by cathode arc evaporation deposition *** kinds of nitrogen pressures were used to deposit both AlTiN–Cu and AlTiN/AlTiN–Cu *** and cross-sectional morphologies of films were observed by scanning electron microscopy(SEM).Crystal structure of films was analyzed by X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).Hardness and adhesion of films were measured by nano-indentation and nano-scratch *** tests were performed under milling conditions during wet machining of TC4 *** results show that with addition of Cu,more droplets occur on AlTiN coating surface,but the grain size of it is refined,and the hardness decreases but the toughness is *** higher N2 pressure,the defects on the surface of AlTiN–Cu and AlTiN/AlTiN–Cu coatings diminish,and the hardness of them is enhanced,while the adhesion is *** to AlTiN coated cemented carbide tool,the lifetimes of AlTiN–Cu and AlTiN/AlTiN–Cu coated tools under the same N2 pressure are improved by 11%and 24%,respectively.

关键词： coated cemented carbide AlTiN–Cu AlTiN/AlTiN–Cu N2 pressure milling

Microstructure and physical properties of PVD TiN/(Ti, Al)N multilayer coatings

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中国有色金属学会会刊：英文版 2005年第5期15卷 1072-1076页

作者：吴恩熙陈利尹飞汪秀全 State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 China State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 China Zhuzhou Cemented Carbide Cutting Tools Co. LTD Zhuzhou 412007 China

Magnetron sputtered (Ti, Al)N monolayer and TiN/(Ti, Al)N multilayer coatings grown on cemented carbide substrates were studied by using energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy(SEM), nanoindentation, Rockwell A indentation test, strength measurements and cutting tests. The results show that the (Ti, Al)N monolayer and TiN/(Ti, Al)N multilayer coatings perform good affinity to substrate, and the TiN/(Ti, Al)N multilayer coating exhibits higher hardness, higher toughness and better cutting performance compared with the (Ti, Al)N monolayer coating. Moreover, the strength measurement indicates that the physical vapour deposition (PVD) coating has no effect on the substrate strength.

关键词：钛锡多层结构涂层微观结构物理性能金属表面防护

Sintering technology of Ti(C, N) base cermets

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中国有色金属学会会刊：英文版 2009年第S3期19卷 696-700页

作者：周书助谭锦灏彭卫珍王社权李萍 zhuzhou cemented carbide Group corp.ltd School of Metallurgical Engineering Hunan University of Technology

The variations of chemical compositions, phases, microstructure evolution and shrinking of cermets compact debinded in H2 or in vacuum and sintered subsequently in vacuum were studied systematically using chemical analysis, back scattering scanning electron microscopy (SEM), and X-ray diffractometry (XRD). The total carbon of cermets debinded in H2 is lower than that debinded in vacuum by 0.4%-0.5%. The contents of carbon and oxygen are decreased sharply when being sintered at 1 100-1 300 ℃. The decomposition reaction of nitrogen is conducted sharply at 1 300 ℃. However, the decomposition of nitrogen is inhibited while the liquid phase appears, and then begins again above 1 500 ℃. The solution reaction of TaC and Mo2C into ring phase starts at 1 200 ℃, and WC into ring phase at 1 300 ℃ is finished. Therefore, the heating rate during sintering of cermets between 900 ℃ and 1 350 ℃ is important.

关键词： Ti(C, N) cermets sintering composition shrinkage microstructure

Crystal growth of tungsten during hydrogen reduction of tungsten oxide at high temperature

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中国有色金属学会会刊：英文版 2009年第S3期19卷 785-789页

作者：吴湘伟罗劲松陆必治谢晨辉皮志明胡茂中徐涛吴国根余志明易丹青 School of Materials Science and Engineering Central South University zhuzhou cemented carbide Group corp.ltd.

Crystal growth of tungsten during hydrogen reduction of tungsten oxide (WO3) to prepare coarse grain tungsten powder at high temperature (950 ℃) was studied. The phase composition and morphologies of products were investigated by means of XRD and SEM. The results show that the reduction sequence of hydrogen reduction of WO3 is WO3→WO2.9→W18O49→WO2→W. The step of WO2→W is the critical step which determines the grain size of tungsten powder. The partial pressure (pH2O/pH2) of H2O within powder layer shows strong effect on the nucleation and grain growth of tungsten. By increasing the pH2O/pH2 within powder layer, well-developed coarse grain tungsten powder with particle size above 15 μm is obtained. After carburizing, the powder can be used to produce ultra-coarse grain cemented carbide with grain size above 5 μm.

关键词： coarse grain tungsten powder hydrogen reduction of tungsten oxide crystal growth partial pressure

compositional dependence of thermophysical properties in binary alkaline earth borate melts:Insights from structure in short-range and intermediate-range order

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Journal of Materials Science & Technology 2022年第36期131卷 195-203页

作者： Jian Yang Il Sohn Department of Materials Science and Engineering Yonsei UniversitySeoul120749Korea State Key Laboratory of cemented carbide Zhuzhou 412000China

In this work,the thermal conductivity of alkaline earth borate melts was measured using hot-wire method from 1323 to 1623 K,and the thermal diffusivity was extrapolated from the thermal conductivity and heat *** compositional dependence of thermophysical properties was interpreted according to the structure in short-range and intermediate-range *** on the Raman spectroscopy,X-ray photoelectron spectroscopy(XPS),and 11B magic-angle spinning nuclear magnetic resonance(MAS-NMR)spectra,modifier cation with higher field strength prefers the formation of non-bridging oxygens(NBOs)for the charge compensation at high BO_(1.5)/MO ratios.A lower amount of covalent bond and greater isolation of large borate groups lead to a lower thermal conductivity in calcium borate melt compared with strontium and barium *** the large size of Ba^(2+)encounters difficulty in fitting around B^[4]-OB^[4]linkages inside the overcrowded large borate groups when BO_(1.5)/BaO=2.5,promoting the formation of NBOs on the edge of borate groups for the charge compensation of modifier cations and leading to the decline in the thermal *** conductivity plays a major role in regulating the thermal diffusivity at a given temperature since the compositional dependence of volumetric heat capacity is relatively weak compared with that of thermal conductivity.

关键词： Thermal conductivity Magic-angle spinning nuclear magnetic resonance(MAS-NMR) X-ray photoelectron spectroscopy(XPS) Raman spectroscopy Thermal diffusivity

Effect of jet milling on micro-strain behavior and rupture behavior of agglomerates of ultrafine WC powders

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Transactions of Nonferrous Metals Society of China 2019年第10期29卷 2128-2140页

作者： Ya-li SUN Qing-cai LIU Xin HUANG Fa-xing ZHANG Jian YANG Hua MEI college of Materials Science and Engineering Chongqing UniversityChongqing 400044China college of Materials Science and Engineering Sichuan University of Science and EngineeringZigong 643000China college of Chemical Engineering Sichuan University of Science and EngineeringZigong 643000China zhuzhou cemented carbide cutting tools co. Ltd.Zhuzhou 412007China

The Williamson-Hall and uniaxial compression methods were used to study the variations of the micro-strain and stress-strain relations in WC powders after jet milling and ball milling, respectively. The rupture behavior of agglomerates in WC powders was investigated. Meanwhile, the as-obtained WC powders treated by different milling methods were used to fabricate WC-10%co cemented carbides, followed by the performance assessment of cemented carbides. The results show that the micro-strain of the jet-milled WC powders decreases significantly compared with that of the ball-milled WC powders, and that the cemented carbides prepared by jet-milled WC powders exhibit excellent properties with a transverse-rupture strength of 4260 MPa, due to the elimination of agglomerates and the reduction of lattice strain.

关键词： ultrafine WC powder micro-strain stress-strain relation jet milling agglomerate rupture mechanism

Thermal behavior and structure of Fe_(84)Nb_7B_9 nanocrystalline powders

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中国有色金属学会会刊：英文版 2006年第2期16卷 299-303页

作者：曹玲飞汪明朴谢丹郭明星李周谭望徐根应 School of Materials Science and Engineering Central South University Changsha 410083 China School of Materials Science and Engineering Central South University Changsha 410083 China Zhuzhou Cemented Carbide Group Co Ltd Zhuzhou 412000 China School of Materials Science and Engineering Central South University Changsha 410083 China Department of Science and Technology of Anhui Province Hefei 2300 01 China

The thermal behavior of Fe84Nb7B9 nanocrystalline powders were analyzed by DTA, XRD and TEM measurements. The results show that nanocrystalline powders with grain size of less than 10 nm can be prepared by mechanical alloying. After annealed below 770 ℃, the obtained powders remain in the scale of nanometer without new phases formed, exhibiting good thermal stability. On its DTA curve, a wide temperature interval of 450 ℃ between its two exothermic peaks can be observed. The powders in as-milled state has bcc structure of supersaturated solid solution type, and nanocrystalline together with amorphous phases can be observed in the powder annealed at 350 ℃, which is beneficial for the good soft magnetic properties.

关键词： Fe84Nb7B9 纳米晶非晶态合金热分析结构