氧化铝陶瓷表面化学镀镍工艺及镀层性能研究

目的在氧化铝陶瓷表面化学镀金属镍镀层,研究施镀时间对Al_2O_3陶瓷表面化学镀镍层的表面形貌、组织结构、显微硬度、表面粗糙度和镀镍层结合力的影响。方法所用镀液组成及工艺参数为:NiSO_4·6H_2O_25g/L,NaH_2PO_2·H_2O 22g/L,Na_3C_6H_5O_7·2H_2O 64g/L,(NH_4)SO_4 62g/L,pH=5.0~6.0,水浴加热至90℃,施镀时间1~4h。采用NovaNanoSEM50型场发射扫描电子显微镜观察镀层的表面微观形貌,采用TH765型自动显微硬度仪测试镀层硬度,采用OLS4000型三维形貌测量仪测量镀层表面粗糙度,采用压入法和热震试验评价镀层的结合性能。结果施镀时间为1~4h时,1h镀层表面金属光泽性好,呈银白色,4h镀层表面更为细腻,但表面光泽性较差。随着施镀时间的增长,Al_2O_3陶瓷表面化学镀镍层表面越光滑,显微硬度越大。不同施镀时间下的化学镀层均没有出现起泡、片状剥落或者与氧化铝基体分离等现象。结论施镀时间为1~4h时,在温度和pH不变的情况下,随着施镀时间增加,化学镀镍层厚度变化不大,但是镀层颗粒更细小,显微硬度明显提高,表面粗糙度降低,镀层结合力良好。

Electroless Nickel Plating Process and Properties of Alumina Ceramics

The work aims to study the effects of plating time on surface morphology, microstructure, microhardness, surface roughness and adhesion of electroless nickel plating on alumina. Plating bath composition and process parameters were as fol-lows: NiSO4·6H2O 25 g/L, NaH2PO2·H2O 22 g/L, Na3C6H5O7·2H2O 64 g/L, (NH4)SO462 g/L, pH=5.0~6.0, heating in water bath to 90℃ and plating time 1~4 h. Surface morphology of the coatings was observed by using NovaNanoSEM50 field emis-sion scanning electron microscopy (SEM), hardness by TH765 automatic microhardness tester, surface roughness by OLS40003D measurement instrument and adhesion strength by thermal shock test and in indentation method. Provided with plating time of 1~4 h, the coatings exhibited good metallic glossiness and looked silvery white after 1 h, the coating was more delicate after 4 h, but the surface gloss was poor. As the deposition time prolonged, the smoother surface of nickel plating on Al2O3was, the higher its microhardness would be; the electroless coatings were free from blistering, flaking or with separation from alumina matrix. Provided with the plating time of 1~4 h, unchanged temperature and pH, as the plating time prolongs, the thickness of coatings changes slightly, the coating grains are finer, microhardness increases obviously and surface roughness reduces. Also, the coating exhibits good adhesion to substrate.