磁控溅射制备CrMoAlN梯度薄膜的抗高温氧化性能

摘要

采用非平衡磁控溅射离子镀技术在M2工具钢和单晶Si表面沉积CrMoAlN梯度薄膜,并在静态空气中进行600、700、800、900℃的高温氧化实验.采用XRD、SEM、XPS、纳米压痕和划痕实验等研究,结果表明:CrMoAlN薄膜呈现与CrN相似的面心立方结构,主要以CrN、AlN和γ-Mo2N形态存在.经800℃氧化2 h后,CrMoAlN薄膜基本保持常温时的晶体结构与力学性能.随着氧化温度继续升高,薄膜表层的MoO3加速挥发,破坏由Cr2O3和Al2O3组成的致密氧化层,薄膜表面出现细小孔隙,薄膜氧化程度加剧.经900℃氧化2 h后,CrMoAlN薄膜的力学性能和膜/基结合强度均出现明显下降.%CrMoAlN gradient coatings were deposited on M2 and silicon wafers by closed-field unbalanced magnetron sputtering ion plating(CFUMSIP)technique, and their high-temperature oxidation behaviours were studied after static oxidation tests in air at different temperatures (600, 700, 800, 900℃) for 2h. The chemical composition, structural, hardness and adhesive/cohesive strength of the coatings were characterized by EDS, XRD, XPS, SEM, nanoindentation and scratch test. The experimental results show that CrMoAlN coatings exhibit a single phase cubic structure. After oxidation at 800℃ for 2 h, the CrMoAlN coatings still retain basically their crystalline structure and mechanical properties. The volatilization reaction rate of MoO3increases, the dense and protective oxide layer consisting of Cr2O3 and Al2O3 is broken. The porous become clearly observable on the surface of the coating, which provides fast diffusion paths for oxygen and cations, and thus promotes the growth rates of oxide scales. After oxidation at 900℃ for 2 h, the mechanical properties and adhesive strength decrease drastically.