【摘要】 采用球环法研究了用大功率ＤＣＰｌａｓｍａＪｅｔＣＶＤ沉积的无衬底自支撑金刚石厚膜的断裂强度和断裂韧度，并试图探索其与原始显微组织特征（特别是晶粒度）的关系。发现ＣＶＤ金刚石膜的强度和断裂韧度均远低于天然Ⅱａ型宝石级金刚石单晶。对于未抛光的试样，数据的离散程度掩盖了任何可能存在的规律性，而对于经过抛光的试样，研究结果表明与众所周知的ＰｅｔｃｈＨａｌ公式有相当好的吻合，说明细化晶粒仍然是提高ＣＶＤ金刚石膜力学性能的有效途径。预先存在的内部裂纹是ＣＶＤ金刚石膜强度低的重要原因之一。更多还原

【Abstract】 Ball on Ring Method was employed to investigate the fracture strength and fracture toughness of free standing thick diamond films prepared by high power DC Arc Plasma Jet CVD process,with emphasis on the inter relationship with the original microstructures(particularly grain size).It was found that the strength and toughness of CVD diamond films were much lower than that of natural type Ⅱ[KG-*4〗a single crystal diamond.The data for un polished as grown free standing diamond films were so scattered that it was not possible to find any correlation to their micro structural features.Whilst for polished samples,a careful study revealed the good coincidence with the well known Petch Hall equation relationship,indicating that grain refinement is still an effective way for improving the mechanical properties of CVD diamond films.Pre existing micro cracks are the important factor responsible to the low value of fracture strength and toughness.更多还原