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某些碳化物形成元素,在高温下与工件的碳结合,在表面上形成一层硬度高、耐磨性好、耐蚀性强的致密碳化物层,可使工件寿命显著提高,这就是常说的扩散被覆法。这种方法目前已广泛应用在工模具及机械零件上。用盐浴法进行扩散被覆,具有设备简单、操作方便、无环境污染及被覆工件可重复处理等优点。因此,这种化学热处理工艺越来越受到人们重视。本文以扩散被复V、Nb、Cr为主,从被覆方法、效果、机理、应用及存在问题,作一概括介绍。一、被覆方法碳化物被覆法有喷镀法、电火花硬化法,扩散法等。喷镀法虽然有温度不高、工件变形小、材质不限的优点,但设备复杂,处理后还需精修,不便推广。电火花硬化法虽然处理件也不变形、且容易被覆,但面积较大时,处理时间长,表面光洁度差,覆层厚度和组织也不均匀。用扩散法对钢表面进
Some of the carbide-forming elements combine with the carbon of the workpiece at elevated temperatures to form a dense layer of carbide with high hardness, good wear resistance, and high corrosion resistance on the surface, resulting in a significant increase in the life of the workpiece, which is often Said the proliferation of covered law. This method has been widely used in molds and machinery parts. With salt bath diffusion coating, with simple equipment, easy operation, no environmental pollution and coated workpiece can be repeated treatment and so on. Therefore, this chemical heat treatment process more and more attention. In this paper, the diffusion is complex V, Nb, Cr-based, from the coating method, effect, mechanism, application and existing problems for a general introduction. First, the coating method Carbide coating method with spraying method, EDM hardening method, diffusion method. Although the thermal spraying method is not high temperature, the workpiece deformation is small, the advantages of material is not limited, but the equipment is complex, need to be refined after treatment, inconvenience to promote. EDM hardening method, although the deformation is not the treatment, and easy to cover, but the larger area, the processing time is long, poor surface finish, coating thickness and texture are not uniform. Diffusion method on the steel surface into