钒对过共晶Fe-Cr-Ni-C耐磨涂层的影响

采用反应等离子熔覆工艺制备过共晶Fe-Cr-Ni-C耐磨涂层,涂层组织主要由奥氏体和(Cr,Fe)_7C_3型碳化物以及少量的马氏体组织组成。大量硬度较高的(Cr,Fe)_7C_3型碳化物均匀分布在以奥氏体为主的基体中,使涂层兼具较高的耐低应力磨料磨损能力以及良好的抗氧化性和耐蚀性等优异的综合性能,得到广泛应用。但粗大的脆性初生(Cr,Fe)_7C_3型碳化物在磨损过程中容易发生破碎而剥落。为了提高Fe-Cr-Ni-C涂层的耐磨性,本文研究了不同钒含量对涂层组织和性能的影响。采用粉末等离子熔覆工艺,在Fe-Cr-Ni-C自熔性合金粉末的基础上分别加入2%、4%、6%、8%的钒,制备出不同钒含量的过共晶Fe-Cr-Ni-C涂层。利用光学显微镜、扫描电子显微镜、X射线衍射仪、显微硬度计、磨料磨损试验等手段,对涂层的组织和性能进行分析。试验结果表明,钒主要分布在(Cr,Fe)_7C_3型碳化物中,形成强度更高的(Cr,Fe,V)_7C_3型碳化物。涂层的硬度和耐磨性随着钒含量的增加逐渐提高;当钒含量为6%时,涂层成形良好,涂层中没有发现裂纹,相对于不加钒的Fe-Cr-Ni-C涂层,耐磨性提高了1.65倍。所以在Fe-Cr-Ni-C耐磨涂层中加入适量的钒,可以增加(Cr,Fe)_7C_3型碳化物的强度,有效提高涂层的耐磨性。

Effects of V on Hypereutectic Fe-Cr-Ni-C Wear Resistant Coating

The eutectic Fe-Cr-Ni-C wear-resistant coating was prepared by reactive plasma deposition. The coating structure mainly consisted of austenite and(Cr, Fe)7C3 type carbide and a small amount of martensite. Many carbides of(Cr, Fe)7C3 type with higher hardness were uniformly distributed in the austenite-based matrix,which made the coating have excellent comprehensive properties such as high abrasive wear resistance, good oxidation resistance and corrosion resistance. However, the coarse brittle primary(Cr, Fe)7C3 carbides were prone to fragmentation and exfoliation during wear. In order to improve the wear resistance of Fe-Cr-Ni-C coating, the effects of different vanadium content on the structure and properties of the coating were studied.The hypereutectic Fe-Cr-Ni-C coatings with different vanadium contents were prepared by powder plasma cladding with 2%, 4%, 6% and 8% vanadium respectively added on the basis of Fe-Cr-Ni-C self-fluxing alloy powder. The structure and properties of the coatings were analyzed by means of optical microscopy, scanning electron microscopy, X-ray diffraction, microhardness tester and abrasive wear test. The experimental results showed that vanadium mainly distributed in(Cr, Fe)7C3 carbides and formed(Cr, Fe, V)7C3 carbides with higher strength. The hardness and wear resistance of the coatings increased with the increase of vanadium content. When the vanadium content was 6%, the coatings formed well and no cracks were found in the coatings. Compared with the Fe-Cr-Ni-C coatings without vanadium, the wear resistance was increased by 1.65 times. Therefore, the strength of(Cr, Fe)7C3 carbides can be increased and the wear resistance of Fe-Cr-Ni-C wear-resistant coatings can be effectively improved by adding appropriate vanadium.