ZM6镁合金的冷喷铝涂层工艺及耐腐蚀性能研究

Research on Cold Spray Aluminum Coating Process and Corrosion Resistance of ZM6 Magnesium Alloy

为提高镁合金的耐腐蚀性能,在ZM6镁合金基体上采用冷喷涂工艺制备铝涂层,研究了冷喷涂工艺参数(气体温度和压力、喷枪距离及压力)对铝涂层质量的影响,得出最佳工艺参数并利用该最佳工艺参数制备出铝涂层进行盐雾试验。试验结果表明:冷喷涂铝涂层的最佳工艺参数为:温度310℃、气体压力2.0 MPa、喷涂距离20 mm、基板相对移动速度30~50 mm s。冷喷涂铝的薄涂层盐雾腐蚀的腐蚀产物为Al_(2)O_(3)、Al(OH)3、Mg(OH)_(2)和MgCl_(2)。随着时间的增长,薄铝涂层被击穿并与镁合金发生电偶腐蚀,加速了基体的腐蚀。冷喷涂铝的厚涂层由于表面形成致密而连续的氧化膜,阻碍了腐蚀介质的侵入,对镁合金基体产生了较好的防护作用。利用最佳工艺参数制备的冷喷涂铝的厚涂层耐盐雾时间超过1200 h。

In order to improve the corrosion resistance of magnesium alloy,aluminium coating was prepared by cold spraying process on ZM6 magnesium alloy matrix.The effects of cold spraying process parameters(gas temperature and pressure,spraying distance and pressure)on the quality of aluminium coatings were investigated,and the optimum process parameters were obtained and used to prepare aluminium coatings for salt spray test.The test results show that the optimum process parameters for cold spraying aluminium coating include temperature of 310℃,gas pressure of 2.0 MPa,optimum distance of spraying of 20 mm,and relative movement speed of the substrate of 30-50 mm s.The corrosion products of salt spray corrosion of cold sprayed aluminium thin coatings are Al_(2)O_(3),Al(OH)3,Mg(OH)_(2),and MgCl_(2).With the growth of time,the thin aluminium coatings are punctured and galvanic coupling corrosion with magnesium alloy occurred,which accelerates the corrosion of the substrate.The thick coating of cold sprayed aluminium produces a better protective effect on the magnesium alloy substrate due to the formation of a dense and continuous oxide film on the surface,which hinders the intrusion of corrosive media.The salt spray resistance time of the thick coating of cold sprayed aluminum prepared using the optimal process parameters exceeds 1200 hours.