哈氏合金表面脉冲电镀镍层的制备及其耐蚀性能

采用双脉冲电镀法在哈氏合金表面制备了纯镍涂层,主要研究了正向脉冲电流密度和正向周期对电镀镍层质量的影响及其耐熔盐腐蚀性能.结果表明:随着正向电流密度和正向周期的增加,镀层厚度增大,显微硬度呈先增后减的趋势.在本实验条件下,当正向电流密度为30 A/dm2、正向周期为70 ms时,镀层质量较好.哈氏合金基材和镀镍涂层的哈氏合金试样的腐蚀失重分别为0.083 7 mg/mm2和0.053 1 mg/mm2,基材经熔盐腐蚀后由于Cr元素大量流失而呈现典型的沿晶腐蚀特点,但镀镍试样经腐蚀后镀镍层仍与基材紧密结合,基体区组织未发生明显变化,优化制备的电镀纯镍涂层显著提高了哈氏合金基体的耐熔盐腐蚀性能.

Preparation and Corrosion Resistance of Pulsed Electroplating Nickel Coating on the Surface of Hastelloy-N Alloy

A pure nickel coating was prepared on the surface of Hastelloy-N alloy by dipulse electroplating.The effects of forward pulse current density and period on the quality of pure nickel coating and its corrosion resistance to molten salt are studied.The results show that the thickness of the coating increases with the increase of forward current density and period.The microhardness increased first and then decreased.Under the experimental conditions,when the forward current density was 30 A/dm^2and the forward period was 70 ms,the quality of the coating is better.The corrosion weight loss of the substrate material and the nickel coated specimen is 0.083 7 mg/mm² and 0.053 1 mg/mm²,respectively.The corrosion of the substrate is due to the large amount loss of Cr after molten salt corrosion and the corrosion behavior along the grain boundary typically.However,the the nickel coating is still tightly bonded with the substrate after corrosion,and the microstructure of the substrate does not change obviously.The corrosion resistance of the Hastelloy-N alloy is improved significantly by the optimized electroplating pure nickel coating.