Ti-Al-Si-N多层梯度涂层的微观结构及力学性能研究

Research on Microstructure and Mechanical Properties of Ti-Al-Si-N Multilayer Gradient Coating

目的分析Ti-Al-Si-N多层梯度涂层微观结构特征和力学性能,得到涂层强化机制。方法采用阴极电弧离子镀镀膜工艺,使用4个靶材交替沉积的方式,分别在高速钢和Si基底上制备Ti-Al-Si-N多层梯度涂层。采用X射线衍射仪(XRD)、高分辨透射电镜(HRTEM)和纳米压痕仪对Ti-Al-Si-N多层梯度涂层晶相组织、微观结构和力学性能进行了表征。结果Ti-Al-Si-N多层梯度涂层中主要相为(Ti,Al)N晶相,择优取向(200)。Ti-Al-Si-N多层梯度涂层由TiN、TiAlN、TiAlSiN三种层区组成,层区厚度分别为41.7、1458.3、1450 nm。通过HRTEM实验观察TiN、TiAlN层区结构发现,在TiAlN层区内部形成了TiAlN/TiN周期变化的结构,证实为TiAlN/TiN纳米多层涂层微结构特征,其中TiN调制层为1 nm左右,TiAlN调制层约为0.5 nm,调制周期约为1.5 nm。此外,发现TiAlN层区存在nc-TiAlN/α-Si3N4结构,TiAlN晶粒大约为6 nm左右,非晶层Si3N4大约为2~3 nm。制备的Ti-Al-Si-N多层梯度涂层硬度为27.7 GPa,弹性模量为338.0 GPa。结论构建了Ti-Al-Si-N多层梯度涂层示意图,对于涂层的强化机制,可以用模量差理论、交变应力场理论及nc-TiN/α-Si3N4模型进行说明,其主要强化机制为nc-TiN/α-Si3N4模型理论。

The microstructure characteristics of Ti-Al-Si-N multilayer gradient coating were obtained,the mechanical properties of the coating were analyzed,and the strengthening mechanism of the coating was obtained.Ti-Al-Si-N multilayer gradient coatings were prepared on high speed steel and Si substrates by cathodic arc ion plating with four targets alternately deposited.The crystal structure,microstructure and mechanical properties of the Ti-Al-Si-N multilayer gradient coating were characterized by X-ray diffractometer(XRD),high resolution transmission electron microscope(HRTEM),and nanoindentation instrument.The main phase in Ti-Al-Si-N multilayer gradient coating is(Ti,Al)N crystal phase with preferred orientation of(200).Ti-Al-Si-N multilayer gradient coating consists of TiN,TiAlN and TiAlSiN layers with thickness of 41.7,1458.3 and 1450 nm,respectively.The structure of TiN and TiAlN layers was observed by HRTEM.It is found that TiAlN/TiN periodic structure is formed in TiAlN layer,and confirmed as the microstructure of TiAlN/TiN nano multilayer coating.The TiN modulation layer is about 1 nm,TiAlN modulation layer is about 0.5 nm,and the modulation period is about 1.5 nm.In addition,it is found that there is nc-TiAlN/α-Si3N4 structure in the TiAlN layer.The grain size of TiAlN is about 6 nm,and that of amorphous Si3N4 is about 2~3 nm.The hardness and elastic modulus of Ti-Al-Si-N multilayer gradient coating are 27.7 GPa and 338.0 GPa respectively.The schematic diagram of Ti-Al-Si-N multilayer gradient coating is constructed.The strengthening mechanism of the coating can be explained by modulus difference theory,alternating stress field theory and nc-TiN/α-Si3N4 model.The main strengthening mechanism is nc-TiN/α-Si3N4 model theory.