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在20R钢表面化学镀Ni-P合金镀层,结果表明:制备的镀层表面平整致密无裂纹,P含量为10.72%,属于高磷非晶镀层。对镀层热处理后的结构、表面形貌、结合强度等性能进行了测试分析,发现Ni-P镀层经200℃热处理后仍保持非晶态结构并且结合强度更好,升温至300℃后开始析出Ni_3P相,镀层转化为混晶态结构。采用电化学试验方法研究经200℃热处理后Ni-P镀层及常用钢材20R、ND钢和316L不锈钢的耐蚀性,发现Ni-P镀层相对于20R、ND钢和316L不锈钢在5%硫酸溶液中的自腐蚀电位更高,为-234 m V,自腐蚀电流密度更小,为3.8687×10~(-6)A·cm~(-2),电荷转移电阻更大,为954.9Ω·cm~(-2),体现了更好的抗硫酸腐蚀性能;对四种材质在60℃不同浓度硫酸溶液中进行实验室均匀腐蚀试验,它们的年腐蚀率排序为20R?ND?Ni-P>316L。
The surface of 20R steel was electrolessly plated with Ni-P alloy. The results showed that the surface of the coating was smooth and compact without crack, and the content of P was 10.72%. It belongs to high phosphorus amorphous coating. The structure, surface morphology and bonding strength of the coating after heat treatment were tested and analyzed. It was found that the Ni-P coating remained amorphous after 200 ℃ heat treatment and the bonding strength was better. After the temperature was raised to 300 ℃, Ni_3P Phase, the coating into mixed crystal structure. The corrosion resistance of Ni-P coating and 20R, ND steel and 316L stainless steel after heat treatment at 200 ℃ was studied by electrochemical test. It was found that the Ni-P coating was stable in 5% sulfuric acid solution compared with 20R, ND steel and 316L stainless steel The self-corrosion potential is higher, which is -234 mV, the self-corrosion current density is smaller, which is 3.8687 × 10 -6 A · cm -2 and the charge transfer resistance is larger, which is 954.9 Ω · cm ~ (-2), showing better resistance to sulfuric acid corrosion; the four materials in different concentrations of sulfuric acid solution at 60 ℃ laboratory uniform corrosion test, the annual corrosion rate of the order of 20R? ND? Ni-P> 316L .