基于热扩散法的钢基表面钛复合膜的制备及性能研究
发布时间：2019-03-05 07:38
【摘要】：磨损、腐蚀和疲劳是机械零件或构件失效的三种最主要的形式,表面改性处理技术是解决这一问题的一种行之有效的手段。热反应扩散法作为表面硬质涂层制备方式的一种,具有成本较低,操作简单,渗层性能优异的特点。钛复合膜由于其优异的物理化学性能被广泛用于材料的表面强化改性以提高材料的显微硬度、耐磨以及耐腐蚀性能。目前,采用热反应扩散法制备钛复合膜的工艺还不成熟,比如盐浴的挥发性和氧化性问题还有待解决。本文中,对钢基体进行预先渗碳和渗氮的处理以降低反应温度并缩短反应时间来解决这一问题。本文分别对20钢预先渗碳以及45钢预先渗氮后的试样进行盐浴渗钛处理,并对其显微结构和性能进行了一定的研究。得到了以下几点主要的结论:1.20钢渗碳处理过程中析出了渗碳体并形成珠光体组织,共同构成了近表面较厚的渗碳层;45钢渗氮处理后表面形成了三层结构,从上至下依次为化合物层,扩散层以及心部基体组织,其中表面化合物层主要的物相组成为ε-Fe2_3N和γ'-Fe4N。同时,试样外表面还形成了一层较薄的疏松层。2.Ti-Fe合金粉末比Ti02更适合作为盐浴渗钛的钛源,综合考虑盐浴的挥发性,流动性以及所制备渗层的质量,在本实验条件下,900℃×3h是较为理想的盐浴渗钛处理工艺。3.渗碳20钢经900 ℃×3h渗钛处理后,钢基表面形成了致密的TiC渗层,渗层厚度值约为7.5 μm,渗层/基体间界面明显,界面结合力的大小约为52 N,渗层的显微硬度值约为1870±134HV;渗氮45钢经900 ℃ ×3 h渗钛处理后,试样表面形成了 TiCN渗层,渗层中含有Ti-Fe固溶体;渗层厚度值约为8.5 μm,渗层与基体间的界面呈锯齿状,界面结合力的大小为68 N,渗层的显微硬度值约为 1685 ±112 HV。4.渗碳以及渗碳+渗钛复合处理能够有效提高20钢基体的耐磨性。耐磨性的顺序为:渗碳+渗钛20钢渗碳20钢20钢基体。摩擦磨损过程中三种试样主要的磨损机制分别为:擦伤机制+氧化磨损、磨粒磨损、粘着磨损。渗氮处理能够有效降低45钢基体的摩擦系数,但摩擦磨损过程中摩擦系数的变化较大;渗氮+渗钛复合处理对45钢基体的减磨性的影响较小,但摩擦磨损过程中摩擦系数的变化较小。耐磨性的顺序为:渗氮+渗钛45钢45钢基体渗氮45钢。摩擦磨损过程中三种试样主要的磨损机制分别为:氧化磨损、磨粒磨损、粘着磨损。相较而言,TiCN渗层比TiC渗层具有更加优异的摩擦磨损性能。5.渗碳以及渗碳+渗钛复合处理可以降低试样的腐蚀速率提高其耐蚀性,耐腐蚀性顺序为:渗碳20钢渗碳+渗钛20钢20钢基体;渗氮处理也可有效提高试样的耐腐蚀性,但经渗钛复合处理后试样的耐腐蚀性反而略微下降。相比TiC渗层,TiCN渗层自腐蚀电位更高,自腐蚀电流更小,具有更加优异的耐腐蚀性能。
[Abstract]:Wear, corrosion and fatigue are the three main forms of failure of mechanical parts or components. Surface modification is an effective method to solve this problem. As one of the preparation methods of hard coating, the thermal reaction diffusion method has the advantages of low cost, simple operation and excellent properties of the coating. Because of its excellent physical and chemical properties, titanium composite films have been widely used in surface strengthening modification to improve the microhardness, wear resistance and corrosion resistance of the materials. At present, the process of preparing titanium composite film by thermal reaction diffusion method is not mature, such as the volatility and oxidation of salt bath still need to be solved. In this paper, the pre-carburizing and nitriding of the steel substrate is carried out to reduce the reaction temperature and shorten the reaction time to solve this problem. In this paper, pre-carburizing of 20 steel and pre-nitriding of 45 steel were treated by salt bath titanium, and their microstructure and properties were studied. The main conclusions are as follows: 1. Cementite was precipitated and pearlite was formed in the Carburizing process of steel 20, which together formed a thick cementite layer near the surface; The surface of 45 steel was nitrided into three layers: compound layer, diffusion layer and core matrix structure from top to bottom. The main phase composition of the surface compound layer was 蔚-Fe2_3N and 纬'- Fe4N.. At the same time, a thin loose layer was formed on the outer surface of the sample. 2.Ti-Fe alloy powder is more suitable for titanium source in salt bath than Ti02, considering the volatility and fluidity of salt bath and the quality of the prepared layer. Under the experimental conditions, 900 鈩，
本文编号：2434676
[Abstract]:Wear, corrosion and fatigue are the three main forms of failure of mechanical parts or components. Surface modification is an effective method to solve this problem. As one of the preparation methods of hard coating, the thermal reaction diffusion method has the advantages of low cost, simple operation and excellent properties of the coating. Because of its excellent physical and chemical properties, titanium composite films have been widely used in surface strengthening modification to improve the microhardness, wear resistance and corrosion resistance of the materials. At present, the process of preparing titanium composite film by thermal reaction diffusion method is not mature, such as the volatility and oxidation of salt bath still need to be solved. In this paper, the pre-carburizing and nitriding of the steel substrate is carried out to reduce the reaction temperature and shorten the reaction time to solve this problem. In this paper, pre-carburizing of 20 steel and pre-nitriding of 45 steel were treated by salt bath titanium, and their microstructure and properties were studied. The main conclusions are as follows: 1. Cementite was precipitated and pearlite was formed in the Carburizing process of steel 20, which together formed a thick cementite layer near the surface; The surface of 45 steel was nitrided into three layers: compound layer, diffusion layer and core matrix structure from top to bottom. The main phase composition of the surface compound layer was 蔚-Fe2_3N and 纬'- Fe4N.. At the same time, a thin loose layer was formed on the outer surface of the sample. 2.Ti-Fe alloy powder is more suitable for titanium source in salt bath than Ti02, considering the volatility and fluidity of salt bath and the quality of the prepared layer. Under the experimental conditions, 900 鈩，
本文编号：2434676
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