S. Liu
,
D.Q. Yi
金属学报(英文版)
The La doped WC/Co powder was prepared by high energy ball milling. The changesof crystal structure, micrograph and defect of the powder were investigated by means ofXRD (X-ray diffraction), SEM (scanning electron microscope) and DTA (differentialthermal analysis). The results show that adding trace La element into carbides iseffective to minish the grain size of WC/Co powder. The La doped carbides powderwith grain size of 30nm can be obtained after 1Oh ball milling. The XRD peak of Cophase disappeared after 20h ball milling, which indicated solid solution (or secondarysolid solution) of Co phase in WC phase. The La doped powder with grain size of1Ohm is obtained after 30h ball milling. A peak of heat release at the temperatureof 470℃ was emerged in DTA curve within the range of heating temperature, whichshowed that the crystal structure relaxation of the powder appeared in the process ofhigh energy ball milling. After consolidated the La doped WC/Co alloy by high energyball milling exhibits ultra-fine grain Sizes and better mechanical properties.
关键词:
cemented carbide
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S. Liu
,
Z.M. Yu
,
D.Q. Yi
金属学报(英文版)
Diamond films were deposited on the cemented carbide WC-15%Co substrates by a hot-filament chemical vapor deposition reactor. The substrate surfaces were chemically pretreated by the following two-step etching method: first using Murakami reagent for 1-3min, and second an HNO3:HCl=1:1 solution for 10-40min. It is indicated that the Co content of the substrate surfaces could be reduced from 15% to 0.81-6.04% within the etching depth of 5-10μm, the surface roughness of the substrates was increased up to Ra=1.0μm, and the substrates hardness was decreased from 89.0 HRA to 83.0HRA after the two-step etching. It is observed that the morphologies of the diamond films on the WC-15%Co substrates emerge in various shapes. The indentation testing shows that the good adhesion between diamond film and the substrate after HF CVD deposition could be obtained.
关键词:
chemical pretreatment
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