高体积分数(Cr,Fe)_7C_3增强Fe基涂层的组织及耐磨性研究

Microstructure and Wear Resistance of High Volume Fraction Carbide(Cr,Fe)_7C_3 Reinforced Fe Based Coating

以FeCrNiBSi与Cr3C2粉末为原料,采用等离子熔覆技术在Q235表面通过原位反应制备了高体积分数六方柱(Cr,Fe)7C3碳化物增强Fe基涂层,利用光学显微镜(OM)、扫描电镜(SEM)、电子能谱(EDS)、XRD射线衍射观察分析了涂层的显微组织结构,同时在M-2000型磨损试验机上考察了恒载荷及变载荷涂层滑动干摩擦时的耐磨性能.结果表明:涂层主要组织为初生(Cr,Fe)7C3碳化物、α-Fe及未溶的Cr3C2,其中(Cr,Fe)7C3在整个涂层中的分布较均匀,平均体积分数达75%,显微硬度为HV0.5(1 218～1 524),由于高体积分数硬质相的存在,涂层恒载荷下相对耐磨性为纯FeCrNiBSi涂层的9倍,变载荷下相对耐磨性为纯FeCrNiBSi涂层的14倍,涂层的磨损机制为(Cr,Fe)7C3碳化物在高切向应力作用下产生裂纹,发生脆性剥落,随着载荷的增加,逐渐由磨粒磨损转变为氧化磨损.

An anti -wear coating with high volume fraction hexagonal prism carbide （Cr, Fe）7C3 as the reinforcing phase was fabricated by in - situ reaction method on a low carbon steel Q235 plate by plasma cladding process with FeCrNiBSi and Cr3 C2 powders. Microstructure of the coating was characterized by using optical microscopy, scanning election microscopy, X - ray diffraction, energy dispersive spectrometer. Wear tests were conducted on a M - 2000 tester with the constant load and variable load. The results show that the coating mainly consisted of primary carbide （Cr, Fe）7C3, α - Fe and the uncompletely dissolved Cr3 C2. The hexagonal prism carbide （Cr, Fe）7 C3 had high volume fraction （about 75.5% ） , high microhardness （about HV0.5 1 218 - 1 524） and uniformly distributed in the coating. The carbide was resposible for the relative wear resistance of the （Cr, Fe）7C3 coating 9 times and 14 times as that of FeCrNiBSi coating under constant and variable load . The main wear mechanism of the （ Cr , Fe ） 7 C3 carbide reinforced coating was cracked and spalled brittlely of the carbide under high tangential stress. Then, with the increasing loads, the wear mechanism of coating was transformed from abrasive wear to oxidation wear.