钢耐热耐磨复合涂层的制备及Mg的作用

Fabrication of Heat and Wear Resistant Composite Coating on Steel and Role of Mg Element

在Ti-C-3Ni-Al体系中加入一定量的Mg作为添加剂,通过熔体内自蔓延工艺原位制备了TiC/Ni3Al复合涂层。利用DSC、XRD、SEM和EDS分析Mg对体系自蔓延过程、热爆产物成分及其显微结构和复合涂层形貌的影响,测试了复合涂层的显微硬度分布、室温和高温耐磨性。结果表明,加入质量分数为2%的Mg可以有效地净化颗粒表面,降低反应开始温度和缩短反应时间,促进TiC/Ni3Al涂层的形成及与基体的结合;所得涂层在1μm内的TiC颗粒均匀分布在Ni3Al中,涂层与基体呈致密的冶金结合,硬度从涂层到基体呈梯度分布,其高温耐磨性明显高于H13钢。

TiC/Ni3Al composite coating on steel was fabricated by self-propagating high temperature synthesis in Ti-C-3Ni-Al system with addition of a little of magnesium element.The effects of Mg on self-propagating process,composition and microstructure of thermal explosive product as well as microstructure of coating were analyzed by DSC(differential scanning calorimetry),XRD(X-ray diffraction),SEM(scanning electron microscope)and EDS(energy dispersive spectrum),and micro-hardness and wear resistance at room temperature and high temperature were measured on the composite coating.It is found that addition of 2% Mg can accelerate the formation of TiC/Ni3Al coating and the bonding with the steel by decreasing initial reactive temperature and shortening reactive time as a result of effectively cleaning the surface of TiC particles.TiC particles with size of less than 1μm are uniformly distributed in Ni3Al phase in prepared coating,and metallurgical bonding between coating and steel can be observed,exhibiting gradient distribution in hardness from coating to steel matrix.The wear resistance of the composites is obviously superior to that of H13 steel.