石墨纤维毡表面化学镀La-Ni-B层的制备及其形貌、物相及耐蚀性能

Preparation of Electroless Plating La-Ni-B on Graphite Fiber Felt and Its Morphology,Phase Composition and Corrosion Resistance

为改善毡状多孔性纤维材料的电化学活性,在以无水乙醇为溶剂的化学镀液中,室温下对石墨纤维毡基体化学镀La-Ni-B合金,并对镀层进行热处理,采用扫描电镜、能谱仪、X射线衍射仪对化学镀层的表面形貌、组成元素和物相组成进行表征。在1 mol/L NaOH溶液中对化学镀石墨纤维毡层试样进行全浸泡腐蚀,计算腐蚀失重量并观察腐蚀后的表面形貌;利用电化学Tafel曲线研究化学镀层试样的腐蚀性能;研究了镀液中稀土盐含量及热处理温度对镀层性能的影响。结果表明:化学镀后稀土La已很好地进入了Ni-B合金镀层中,基体表面被一层均匀致密的合金膜覆盖;随着热处理温度的升高,La-Ni-B镀层由非晶态向晶态转化;相同浸泡时间下,3 g/L稀土盐添加量条件下所得合金镀层的腐蚀失重量最小; 200℃热处理温度、3 g/L稀土盐添加量所得合金镀层的耐蚀性最好。

The La-Ni-B composite coating was deposited on the graphite fiber felt in electroless plating solution using hydrous ethanol as a solvent by room temperature,and then followed by the heat treatment.Scanning electron microscopy,energy dispersive spectroscopy and X-ray diffractometer were used to characterize the surface morphology,composition and phase composition of the graphite fiber felt electroless plating.The fully immersed corrosion test of the electroless plating sample in 1 mol/L Na OH solution was used to calculate the corrosion weight loss,and the surface morphology after corrosion was observed.Moreover,the corrosion resistance of the electroless plating sample was studied by Tafel curve,and the influences of the rare earth contents in the plating solution and the heat treatment temperature on the plating properties were investigated.Results showed that the rare earth La entered the Ni-B alloy coating well after electroless plating,and the surface of the substrate was covered by a uniform and dense alloy film.As the heat treatment temperature increased,the La-Ni-B coating transformed from amorphous to crystalline.Under the same immersion time,the alloy coating under 3 g/L rare earth had the least corrosion loss.At crystallization temperature of 200℃,the alloy plating layer of 3 g/L rare earth addition had the best electrochemical corrosion resistance.