喷涂工艺及其粒子状态对涂层结合强度的影响

Effects of Spraying Parameters and Related Particle Status on Coating Bond Strength

热喷涂涂层结合强度是评价涂层质量、满足使用要求的关键指标之一,针对电弧喷涂涂层结合强度较低的问题,以典型Ni Al材料为研究对象,从喷涂工艺和粒子状态方面探讨了其对涂层结合强度的影响。研究结果表明,随着喷涂距离在一定范围内增加,粒子飞行温度和速度相差不大,但涂层界面氧化明显加剧,弱化了变形粒子的结合能力,使得涂层平均结合强度从39.8MPa下降到28.9MPa,此时粒子氧化程度的加剧是导致涂层结合强度降低的主要因素。采用氮气雾化保护后,粒子氧化得到有效控制,但雾化粒子尺寸明显增大,同时飞行粒子的平均温度和速度大幅下降,严重降低了粒子的铺展变形能力,使得涂层平均结合强度由33.2MPa下降到23.8MPa,此时粒子扁平率减小是导致涂层结合强度下降的主要原因。

The bond strength of thermal spraying coating is one of the key indicators for evaluating the quality of coating and estimating the coating to meet the requirements or not. In view of the low bond strength of the arc spraying coating, the typical material of NiA1 was used as the research object and the spray process and particle status were considered to investigate the influence of the bonding strength of coating. The results show that, the flying status of particle were similar with the increase of spraying distance within a certain range, but the oxidation of coating interface intensified significantly and the combining ability of particles were weakened, which lead to the decrease of average bond strength of coating from 39.8 MPa to 28.9 MPa. The main factor resulted in the decrease of coating bond strength is the increase of particle oxidation degree. The oxidation of particle was controlled via protection of nitrogen atomization, but the atomized particle size increased, at the same time, the average temperature and velocity of in-flight particles declined drastically. The spreading ability of particle was severely reduced and which lead to the decrease of average bond strength of coating from 33.2 MPa to 23.8 MPa The decrease of flattening ratio is the main reason for decline in coating bonding strength.