基于纳米复合Ti-Si-N薄膜硬度对界面相微结构及微尺度变化极为敏感的实验事实, 定量表征了薄膜的硬度与氧杂质含量的关系. 结果表明, 与高纯度薄膜40-55 GPa高硬度比较,1%-1.5%的氧杂质含量导致薄膜的硬度下降到30 GPa左右.根据纳米晶界面原子模型和实验结果,氧杂质与纳米尺度界面交互作用所引发的微尺度缺陷是硬度下降的诱因,晶界面的氧杂质密度是薄膜高硬度损失程度的决定因素,单个纳米晶周围的氧杂质覆盖度达到10个原子以上时, 薄膜的硬度只能达到30 GPa.
There has been a wide attention in nanocomposite coatings with interface phases because of their superhardness, but the limitation hardness that this kind of materials can achieve was still an argued question by many researchers. In this paper, we observe the limitation hardness of nanocomposite coatings is very sensitive to microstructure of interface. It is shown that a dependent relation between hardness and oxygen impurity content of coatings resulted from our experiments. Based on an atomic model analysis, the decreasing of hardness caused by a small amount of oxygen impurities can be explained by oxygen atoms induce weakening of the Si3N4 interface which acts as a “glue” between the TiN nanocrystals. Further, we conclude that density of oxygen atoms around grain boundary is a dominant factor on hardness degradation of the films
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