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采用FLiNaK氟化盐对3Cr13不锈钢表面分别进行不同时间的热反应沉积(TD),利用X射线衍射仪(XRD)、电子探针(EPMA)、扫描电镜(SEM)、显微维氏硬度计研究了VC涂层的形貌、成分特征、表面硬度及其生长动力学。结果发现,3Cr13不锈钢的表面形成了3~5μm厚的均匀致密的VC涂层,表面呈花瓣状,VC相中含少量的Si和Fe元素。VC涂层的平均(HV)硬度高达32 220 MPa,其厚度与保温时间满足抛物线关系。VC涂层表面几百纳米厚度存在不均匀分布的SiO_2,表面呈龟裂状。主要是因为SiO_2的热膨胀系数大于VC涂层,使得SiO_2在冷却过程中受到拉应力而发生龟裂。本研究首次表明低熔点高活性的氟化盐可以用于TD法制备VC涂层。
The surface of 3Cr13 stainless steel was subjected to thermal reaction deposition (TD) at different times by using FLiNaK fluoride salt. The structure of 3Cr13 stainless steel was characterized by XRD, EPMA, SEM and micro Vickers hardness tester VC coating morphology, composition characteristics, surface hardness and growth kinetics. The results showed that the surface of 3Cr13 stainless steel formed uniform and dense VC coating of 3 ~ 5μm in thickness, the surface was petal - like, and the VC phase contained a small amount of Si and Fe. The average (HV) hardness of VC coating is as high as 32 220 MPa, and its thickness and holding time satisfy the parabola relationship. The thickness of VC coating surface is unevenly distributed in the thickness of several hundred nanometers, and the surface is cracked. The main reason is that the thermal expansion coefficient of SiO 2 is larger than that of VC coating, which makes the SiO 2 cracked due to tensile stress during the cooling process. This study shows for the first time that fluoride salts with high activity and low melting point can be used to prepare VC coatings by TD method.