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甲烷浓度对硬质合金微型立铣刀表面生长金刚石涂层的影响

Effect of Methane Concentration on Deposition of Diamond Thin Films on Cemented Carbide Micro End-Mill

  • 摘要: 金刚石涂层的应用可显著提升刀具使用寿命。文章采用钽丝为热丝, 氢气、甲烷为反应气体, 通过热丝气相沉积法在不同甲烷浓度下对硬质合金立铣刀表面进行沉积金刚石涂层。通过扫描电子显微镜、拉曼光谱对不同甲烷浓度下金刚石涂层的表面形貌、涂层质量进行分析。结果显示, 随着甲烷浓度增加, 涂层中二次形核率增加、金刚石晶粒尺寸变小, 金刚石晶粒能够完好地嵌入到硬质合金表面形成机械锁扣结构, 提高膜-基结合强度, 但过高的甲烷浓度使得活性氢原子对石墨的刻蚀强度减弱, 使得涂层中金刚石晶粒晶界处非金刚石碳相含量逐渐增加, 涂层质量下降。当甲烷浓度为 3% 时, 硬质合金立铣刀表面金刚石涂层结晶度高、晶粒间接触紧密、涂层中非金刚石碳相含量低、膜-基结合强度高, 端刃处未出现涂层剥落现象。文章工作有助于理解热丝气相沉积法中碳源浓度对表面金刚石涂层沉积效果及涂层失效的影响, 使硬质合金立铣刀表面金刚石涂层沉积工艺得到进一步优化。

     

    Abstract: In order to improve the working life of micro end-mill, the diamond coatings were prepared by hot filament chemical vapor deposition (HFCVD) method with various methane concentrations. Scanning electron microscopy and Raman scattering analyses were carried out to characterize the surface morphology and coating property. With the increasing of methane concentration, the secondary nucleation rate was enhanced and the diamond grain size was decreased, which helped the diamond grain to embed into cemented carbide substrate, and improved film-substrate adhesion. Excess methane concentration weakened the etching ability of atomhydrogen on graphite phase, leading to higher fraction of non-diamond phase among diamond boundaries. While the methane concentration was 3%, the diamond coating deposited on micro end-mill possessed high crystallinity, good adhesion, more compact grains and low non-diamond phase. There was also no delamination occurred at the edge of end-mill. This work not only benefit us from understanding the effect of methane concentration on deposition of diamond film on cemented carbide micro end-mill and the mechanism of diamond film failure, but also provides basis for optimizing the parameters for diamond deposition on end-mills.

     

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