硫酸塩浴からのZn-M-Si0_2複合めっきの析出挙動および耐食性に及ぼす不溶性アノードの影響

摘要

鉄鋼材料は，加工性に富み，熱処理によって容易に機械特 性を変化させることができ，しかも安価であるため，今日ま で基幹素材として最も広く適用されている。しかし，腐食環境下では容易に赤さびが発生し，強度などの性能低下を招い てしまう。そのため，長期信頼性の観点から犠牲防食能を有 する亜鉛めっきあるいは亜鉛系合金めっきが広く適用されて いる。安価で技術的にも成熟している亜鉛めっきは，鉄鋼 部材への防鲭用表面処理として，様々なめっきの中でも適用 量が多く，極めて重要な技術である。%Zinc，niekel-SiO_2 electrodeposition was done using an acid sulfate bath to examine the effects of an insoluble anode on SiO_2 co-deposition behavior and the corrosion resistance of plating. The presence of SiO_2 nanoparticles in the plating bath apparently changes the alloy deposition behavior and improves the macrothrowing power of plating. At an early stage of electrodeposition, the SiO_2 nanoparticle apparently acts as a nucleus of precipitation. The SiO_2 amount co-deposited in the plating film by the indium oxide electrode was greater than that by the platinum electrode. Furthermore, these SiO_2 nanoparticles did not disperse uniformly in a plating film, but instead distributed only in the SiO_2 rich layer formed beneath the surface. Therefore, the anticorrosive performance of the plating film with much SiO_2 co-deposited amount by the iridium oxide electrode was superior to that obtained using a platinum electrode. For the curtailment of zinc use, results show that an indium oxide electrode is preferable to a platinum electrode as an anode for zinc-nickel-SiO_2 electrodeposition.