沉积温度对硬质合金表面MPCVD法制备SiC过渡层的影响

Effects of Temperature on SiC Interlayers on Cemented Carbide Substrates Deposited by MPCVD

采用MPCVD法,以氢气和四甲基硅烷为先驱气体,YG6硬质合金刀片为基体材料,在不同沉积温度下制备了SiC涂层;并选用致密连续且附着性能优良的SiC涂层作为过渡层制备金刚石涂层。使用场发射扫描电镜、能谱仪和掠X射线衍射仪对SiC涂层和金刚石涂层的形貌和组成进行了分析,并对SiC涂层和金刚石涂层的附着力进行测试。结果表明,随着沉积温度升高,SiC涂层先由团聚在一起的β-SiC微晶相先转变为颗粒状和片状β-SiC,进而转变为团聚在一起的非晶态的SiC晶须;SiC涂层的厚度呈递增、致密度呈现先增强后减弱、表面粗糙度整体呈现先减小后增大、附着力呈先升高后降低的趋势。沉积温度为800℃时制备的片状SiC涂层与硬质合金基体有着良好的结合强度,将其作为过渡层时,能够在硬质合金表面制备出均匀、连续、致密的且附着力良好的金刚石涂层。

SiC coatings were deposited on cemented carbide substrates by microwave plasma chemical vapor deposition method using tetramethylsilane and H2as source gas. The effects of temperature on the properties SiC coatings were studied. The SiC coating with high continuous,compact and excellent adhesion to the substrate was chosen as the interlayer for diamond deposition. The morphology and compositions of the SiC coatings and diamond coating were investigated by FESEM,EDS and XRD. The adhesion properties of SiC coatings and diamond coating were studied. The results show that as the deposition temperatures increasing,the morphologies of the SiC coatings firstly transformed from the microcrystalline β-SiC to the granular and layer-microstructure β-SiC,and then to the amorphous SiC whiskers. However,the deposition rates of the SiC coatings increased linearly; the density as well as the adhesion of the coatings were strengthened and then weakened,and the surface roughness was decreasedfirst and then increased as the deposition temperature increasing. SiC coating deposited at 800 ℃ exhibited a layer microstructure and the excellent adhesion to the substrate,thus it was chosen as the interlayer for diamond deposition. Successfully,diamond coating with appealing properties,e. g. strong uniform,high continuous and compact as well as outstanding adhesion was obtained.