金刚石粉体表面CVD法镀钨的工艺研究

目的增强金刚石与基体的界面结合能力。方法首先对金刚石粉体进行"除有机物→除油→粗化→烘干"处理。采用自制化学气相沉积装置,研究了以H_2和WF_6为反应气体在金刚石表面CVD法镀覆钨工艺。使用扫描电镜(SEM)、能谱(EDS)、X射线衍射(XRD)、透射电镜(SEM)等检测方法,分析了金刚石粉体镀层钨的微观形貌、成分、组织结构,对镀层包覆金刚石粉体相关性能进行了初步测试。结果在粒径约为223.6mm的金刚石表面获得均匀致密镀覆层的最佳工艺参数为:沉积温度670℃,沉积时间2 min,H_2通入量1 L/min,WF_6消耗量2 g/min。沉积温度为580℃时,获得的均匀致密钨镀层的厚度为150 nm,且镀层杂质含量较少。将镀覆钨的金刚石和普通金刚石分别与铜粉热压烧结后进行抗弯强度测试,结果显示含镀覆钨的金刚石试样抗弯强度提高了38.6%。加入镀钨金刚石压块的热膨胀系数比加入普通金刚石的有所降低,并且加入的镀钨金刚石粉体越多,压块的热膨胀系数越低。结论镀钨后的金刚石颗粒的表面性能得到改善,与基体的结合能力得到提高。

Technical Study of Tungsten Plating on Surface of Diamond Powder by CVD

The work aims to improve the interface bonding capacity between diamond and the substrate. First, the diamond powder was treated within the sequence of "removing organic matter-degreasing-roughening-drying". By using homemade CVD device, the process of plating tungsten on diamond surface by CVD with H2 and WF6 as reactive gases was studied. Micro mor-phology, composition and microstructure of the diamond powder coating tungsten were analyzed by means of scanning electron microscopy (SEM), electron spectroscopy, X ray diffraction (XRD) and transmission electron microscope (SEM). Preliminary testing was performed in respect of diamond powder covered with coating. The best technological parameters for obtaining uni-form and dense coating on diamond surface with particle size of 223.6μm were: deposition temperature of 670℃, deposition time of 2 min, H2 introduction quantity of 1 L/min and WF6 consumption of 2 g/min. When the deposition temperature was 580℃, thickness of the uniform and compact coating was 150 nm, and less impurities were present in the coating. Bending strength test was performed after hot pressed sintering between tungsten-coated diamond and copper power, common diamond and copper powder. Test results showed that, bending strength of tungsten-plated diamond sample increased by 38.6%, the coef-ficient of thermal expansion coefficient of the sample containing tungsten-plated diamond lock block was lower than that of or-dinary diamond. The more power was added, the coefficient of thermal expansion was lower.Surface properties of the tungsten-plated diamond particles are improved, and the binding capacity of the substrate is improved.