Co-P合金镀层的研究现状

Cr涂层的性能优异,在工业中应用广泛,但Cr(Ⅵ)化合物易致癌,需寻找具有优良摩擦学和耐蚀性能的涂料来替代电镀Cr(Ⅵ)。Co-P合金镀层作为Cr(Ⅵ)涂层的替代品之一,以其独特的物理、化学性能,成为复合材料发展的新秀,日益受到人们的关注和研究。经热处理后的Co-P合金镀层的硬度可达到1224HV,可媲美硬Cr镀层。相较于其他镀层(如纯Ni、纯Co、Ni-P、Ni-Fe、Ni-Co等),Co-P合金镀层具有更好的热稳定性。热循环时,随着循环次数的增加,Co-P合金镀层发生塑性变形→产生热裂纹→与基体脱离→基体受到损害等变化。Co-P合金镀层的厚度均匀且致密,不会产生点蚀等局部效应,大大提高了镀层的耐蚀性能,且高P镀层的耐蚀性优于低P镀层,非晶态Co-P合金镀层的耐蚀性也优于晶态Co-P合金镀层。Co-P合金镀层的摩擦磨损性能较纯Co镀层有很大提高,但P质量分数超过2%后,其耐磨性提升不大。Co-P合金镀层中会有片状磁畴存在,自发磁化强度方向和Co晶粒易磁化方向平行,且镀层越厚,自发磁化的趋向性越强。然而,在制备Co-P合金镀层的过程中,镀液配制和保存,以及废液的回收-处理-再利用环节不够完善等问题没有引起足够的重视。综述了Co-P合金镀层的硬度、热稳定性、耐蚀性、高温耐磨性以及磁性能等的研究现状。

Research Status of Cobalt-Phosphorus Alloy Coatings

Cr coating has been widely used in industry because of its excellent performance.However,Cr (Ⅵ) compounds have carcinogenic effect,coating of good tribological property and corrosion resistance shall be found to replace electroplated Cr (Ⅵ).As one of the substitutes of Cr (Ⅵ) coating,Co-P alloy coating has become a new development of composite materials and is increasingly concerned and studied by people due to its unique physical and chemical properties.After heat treatment,hardness of the Co-P alloy coating could be up to 1224 HV,which was comparable to that of the hard Cr coating.Compared with other coatings (such as pure Ni,pure Co,Ni-P,Ni-Fe,Ni-Co,etc.),the Co-P alloy coating exhibited better thermal stability.In thermal cycle,Co-P alloy was subject to plastic deformation→hot cracking→substrate detachment→substrate damage as cycle indices increased.the Co-P alloy coating was uniform and compact,free from local effects including pitting,which greatly improved corrosion resistance of the coating.Corrosion resistance of high P coating was better than that of low P coating,that of amorphous Co-P alloy coating was better than that of crystalline Co-P alloy coating.Friction and wear properties of Co-P alloy coating was greatly improved compared with pure Co coating,but abrasion resistance improved slightly when the P content exceeded 2wt.％.There was schistose domain in the Co-P alloy coating,spontaneous magnetization direction was parallel with Co grain easy magnetization direction,and the thicker the coating was,the stronger the tendency of the spontaneous magnetization would be.However,in the process of preparing Co-P alloy coating,problems such as preparation and preservation of the plating solution,and incomplete waste liquor recovery-treatment-recycling have not arouse enough attention.The research status of hardness,thermal stability,corrosion resistance,high temperature abrasion resistance and magnetic properties of Co-P alloy coating were reviewed.