碳源浓度对CVD金刚石涂层质量的影响

在自制不锈钢钟罩式HFCVD设备上,以CH3COCH3和H2为气源,采用热丝CVD法在经过碱酸两步法预处理后的YG6硬质合金基体上制备了微米金刚石涂层;利用扫描电镜、Raman光谱仪、洛氏硬度计、维氏硬度计检测涂层的形貌结构、成分、附着性能和硬度,着重考察了碳源浓度对涂层质量的影响。结果表明过低碳源浓度造成涂层晶粒间存在缝隙,而过高的碳源浓度会使涂层晶粒细化,同时非金刚石相成分增加。以两步法工艺预处理基体,当碳源浓度为2%、沉积功率为4 kW、反应气压3 kPa、衬底温度为800℃、热丝基体距离为5 mm时,经4 h生长,可获得厚度为5.36μm、平均硬度HV为8 143.09、平均粒径1~2μm、纯度高、附着性能良好的微米金刚石涂层。

Effect of Carbon Source Concentration on Quality of CVD Diamond Coating

Using self-made stainless steel bell-jar type HFCVD device,micro-crystalline diamond coating was synthesized on the cemented carbide substrates of WC-6wt%Co pretreated by alkali/acid two-step process in CH3COCH3/H2ambient via hot filament chemical vapor deposition;the crystal morphology,chemical quality,adhesion and hardness of the diamond coating were analyzed by means of SEM,Raman spectrum,Rockwell hardness tester and Vickers hardness tester;the effects of different acetone volume fractions on the quality of the diamond coating were mainly investigated.The results show that smaller carbon source concentration causes gaps between the diamond crystal particles of the coating,and higher carbon source concentration leads grain refining as well as increase of sp2 phase content of the coating.Using two-step method substrate pretreatment,micro-crystalline diamond coating with a depth of 5.36 μm,an average hardness of HV8 143.09,an average particle size of 1~2 μm,high chemical purity and better adhesion could be obtained through 4 h growth under the process parameters as follow: CH3COCH3/H2 of 2%,deposition power of 4 kW,reaction pressure of 3 kPa,substrate temperature of about 800 ℃,radiation distance of 5 mm..