CrAlN薄膜高温抗氧化性的研究

Study on High-Temperature Oxidation Resistance of CrAlN Coatings

在900℃,循环氧化20h的试验条件下研究了偏压对CrAlN薄膜抗氧化性的影响。用X射线衍射仪测定薄膜氧化前后的相结构,用场发射扫描电镜观察薄膜氧化前后的表面形貌,并每隔4h测量其氧化增重。结果表明,随着偏压的增加,CrAlN薄膜中的铝含量增加,薄膜的抗氧化性增强。其主要原因是:1)随着铝含量的增加,薄膜表面形成了更多的铬铝混合氧化物,它们充当了氧的扩散阻挡层,减小了高温条件下氧向薄膜内的扩散能力;2)加入的铝与氮以共价键结合,提高了薄膜的热稳定性。

The effect of bias voltage on the oxidation behavior of CrAlN coatings was studied, in air for 20 h at 900℃. The structures and the surface morphologies of CrAtN coatings before and aider oxidation were examined by X-ray diffraction （XRD） and Field Emission Scanning Electron Microscopy （FESEM）. Mass gain was measured every 4 h. The results show that Al concentration in coatings increases and the oxidation resistance of the CrAIN coatings is improved as the increase of the bias voltage. The following conclusions are drawn： 1） more mixed Cr and Al oxide form with the increase of the bias voltage, this mixed oxide layer can act as an effective diffusion barrier slowing clown the inward diffusion of the oxygen at high temperatures; 2） Al and N atoms are covalently bonded which will improve the thermal stability of coatings.