用脉冲直流等离子体辅助化学气相沉积(PCVD)方法在高速钢基体上沉积出新型Ti-Si-C-N超硬薄膜。用XRD、XPS、HRTEM等分析发现薄膜微观组成为纳米晶/非晶复合结构（nc-Ti(C, N)/a-Si3N4/a-C-C）或（nc-Ti(C, N)/h-Si3N4/a-Si3N4/a-C-C）。高温氧化实验结果发现：随Ti含量降低和Si含量增大，Ti-Si-C-N薄膜的抗氧化温度逐步提高。当Ti含量为8.7at.%、Si含量为17.8at.% 时，薄膜中出现少量晶化的h-Si3N4，弥散分布在非晶基体中，这种结构的Ti-Si-C-N薄膜的抗氧化温度达到900℃。分析认为Ti-Si-C-N薄膜中随Si含量增多，非晶Si3N4厚度不断增大或层数增多，且非晶中弥散分布的h-Si3N4和非晶Si3N4强烈阻止氧在晶界的扩散，从而使薄膜的抗氧化性显著提高。研究还发现Ti-Si-C-N薄膜的氧化过程分为增重和失重两个阶段，进入失重阶段后薄膜会很快发生失效。
Superhard nanocomposite Ti-Si-C-N coatings were deposited on substrate of high speed steel using an industrial pulsed d.c. plasma chemical vapor deposition set-up. Detailed microstructure examined by means of XRD, XPS and TEM suggested that the Ti-Si-C-N coatings are a nanocomposite structure composed of nanocrystalline Ti(C, N) and amorphous carbon and Si3N4, occasionally h-Si3N4. Ti(C, N) showed a strong 200 preferred orientation. With Ti content increasing and Si content decreasing, high-temperature oxidation resistance gain improvement gradually. When Ti and Si contents were 17.8at. % and 8.7at. %, respectively, nanocrystals of Si3N4 in the coating were dispersed on an amorphous matrix.The kind of coatings exhibited a much higher temperature (900℃) oxidation resistance. The possible origin of high-temperature of Ti-Si-C-N coating is explained that with increasing Si content, increasing amorphous Si3N4 thickness/layers and h-Si3N4dispersed in the matrix act as an efficient diffusion barrier against oxygen diffusion, which is helpful for improvement of oxidation resistance. Two-stage oxidation process involving mass gain and loss were observed, and the failure of the coating took place in the process of mass loss in the coating.
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| [1] | |
| [2] | |
| [3] | |
| [4] | |
| [5] | |
| [6] | |
| [7] | |
| [8] | |
| [9] | |
| [10] |
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