热处理对不锈钢表面化学镀Ni-Cr-P合金镀层结构及性能的影响

采用化学镀工艺在不锈钢表面获得了Ni-Cr-P合金镀层。研究了Ni-Cr-P非晶态合金膜随热处理温度升高,其结构以及显微硬度和耐蚀性的变化规律,并对变化的原因进行了分析。结果表明,镀态Ni-Cr-P为非晶态镀层,200℃热处理开始晶化,到400℃时Ni3P晶化比较完全,800℃时Ni3P完全分解,生成含Ni、Cr、Fe的合金膜的Cr2Ni3和FeNi2P相。其显微硬度随热处理温度升高而升高,500～600℃之间显微硬度略有下降,600～700℃又随着热处理温度的升高而略有升高,700℃后显微硬度略有下降;合金膜的耐腐性在热处理温度200～400℃间变化较小,500℃热处理后其耐腐蚀性下降厉害,600～700℃随着热处理温度的升高其耐腐蚀性又略有升高,800℃后由于Ni3P的分解其耐腐蚀性又急剧下降。

Effects of heat-treatment on structure and properties of electroless Ni-Cr-P alloy plating on the surface of stainless steel

Ni-Cr-P alloy coatings were deposited on surface of stainless steel by an electroless deposition process.The variation of structure,micro-hardness and corrosion resistance of Ni-Cr-P amorphous alloy film with the increase of heat-treatment temperature was investigated,the reasons for the variation were also discussed.The results show that the as-deposited Ni-Cr-P amorphous coating starts crystallization when annealed at 200 ℃;most of the Ni3P phase are crystallized at 400 ℃,when annealed at 800 ℃,Ni3P completely decomposes with the information of Cr2Ni3 and FeNi2P phase containing element of Ni,Cr and Fe.It is observed that micro-hardness of the coatings increases with heat-treatment temperature increasing to the maximum value at 500 ℃ and then fluctuates slightly when further increasing temperature to 800 ℃.No significant change of corrosion resistance of the alloy film is observed when heat-treated at 200-400 ℃.However,the corrosion resistance of alloy film declines severely after heat treatment at 500 ℃,and it increases slightly again with the increasing of heat-treatment temperature from 600 ℃ to 700 ℃.The corrosion resistance decreases sharply due to the decomposition of Ni3P phase for the Ni-Cr-P alloy coatings heat-treated at 800 ℃.