CrNi3MoVA钢表面电火花沉积NiCrAlY涂层的高速摩擦磨损性能

采用电火花表面沉积技术,在CrNi3MoVA钢表面沉积NiCrAIY涂层.利用纳米压痕仪和摩擦磨损试验机分别测试了CrNi3MoVA钢和NiCrAlY涂层的硬度、弹性模量和摩擦系数,并用SEM和EDS研究了磨损前后的形貌和成分.结果表明电火花沉积NiCrAlY涂层包含β-NiA1和γ-Ni两相,涂层是由柱状晶组成的微晶涂层;NiCrAlY涂层的硬度较CrNi3MoVA钢提高了22％,而弹性模量较CrNi3MoVA钢降低了21％;当摩擦副为淬火G15钢球,加载量为10 N,往复行程为10 mm,往复速率为600 r/min时,CrNi3MoVA钢平稳摩擦系数为0.65—0.75,而NiCrAIY涂层平稳摩擦系数为0.45～0.55,CrNi3MoVA钢表面沉积NiCrAlY涂层对其具有明显的减摩耐磨作用,涂层表面较高的硬度和高速摩擦中形成的粘附力强的薄氧化物层是其耐磨的主要原因;CrNi3MoVA钢的磨损机制主要为粘着磨损,而NiCrAlY涂层为微切削磨料磨损.

High-speed Friction and Wear Performance of NiCrAlY Coating Electrospark Deposited on CrNi3MoVA Steel

A NiCrAIY coating was electrospark deposited on surface of a CrNi3MoVA steel.The hardness,elasticity modulus and friction coefficient of the CrNi3MoVA steel and NiCrA1Y coating were tested by employing the nanoindentor and the friction and wear testing machine,respectively,and then morphologies and composition were investigated before and after wearing by utilizing scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrum (EDS).The results indicated that the NiCrA1Y coating with columnar structure,composed of β-NiA1 and γ-Ni,belongs to microcrystal one.The hardness of the NiCrA1Y coating increased by 22％ than the CrNi3MoVA steel whilst the elasticity modulus reduced by 21％;when the quenched G15 steel ball was used as the friction pair under the wear condition that the load was 10 N,the reciprocating travel was 10 millimeter and the velocity was 600 rounds per minute,the steady friction coefficient of the CrNi3MoVA steel was 0.65-0.75 while that of the NiCrA1Y coating was 0.45-0.55.Therefore the NiCrA1Y coating electrospark deposited on the CrNi3MoVA steel has the function of antifriction and wear resistance mainly due to its higher hardness and good adherent thin surface oxide layer formed during high-speed friction;the mechanism of the CrNi3MoVA steel can be characterized as adhesive wear while that of the NiCrA1Y coating is microcutting abrasive wear.