無電鍍鎳介層厚度對ADI披覆氮化鈦鍍膜耐蝕性之影響

Effect of EN Interlayer Thickness on Corrosion Resistance of TiN Coated ADI

許正勳(C. H. Hsu) ； 陳毅旻(Y. M. Chen) ； 陳貽宗(Y. T. Chen)

《鑄造工程學刊》 42卷2期 (2016/06) Pp. 11-18

摘要

沃斯回火延性鑄鐵(Austempered ductile iron, ADI)雖具有優異的機械性質，但其表面組織會因球墨裸露或剝離造成孔洞現象，不但限制了表面特性，亦導致PVD陶瓷鍍膜披覆效率變差。因此本研究目的為探討無電鍍鎳(EN)介層填補孔洞效果對陰極電弧沉積TiN之影響，即在TiN與基材間分別有5μm、15μm、25μm不同厚度的EN中介層，然後進行有無此複合鍍膜ADI試片之腐蝕試驗。實驗結果顯示：EN中介層愈厚，愈可有效地填補球墨孔洞及降低表面粗度，使得ADI不論在3.5%NaCl或20%H_2SO_4腐蝕溶液中，耐蝕性皆可明顯獲得改善，其中又以25μm -EN中介層搭配TiN的複合鍍膜耐蝕性表現最佳。

關鍵字

沃斯回火延性鑄鐵 ； 無電鍍鎳 ； 氮化鈦 ； 耐蝕性

並列摘要

Austempered ductile iron (ADI) possesses excellent mechanical properties, but there are numerous holes present on its surface due to nodules peeling. These holes limit the efficiency of ceramic coatings by PVD technology. Therefore, this study utilized electroless nickel (EN) as an interlayer with the various thicknesses (5µm, 15µm, 25 µm) to fill the holes before PVD-TiN coating on ADI substrates. Two types of corrosion tests; polarization test and immersion test, were separately conducted in 3.5% NaCl and 20% H_2SO_4 corrosive media. The purpose is to explore the effect of interlayer thickness on the corrosion behavior of ADI. The experimental results show that the efficiency of filling holes increases with the increase of EN interlayer thickness. As a result, the composite coatings could evidently improve the corrosion resistance of ADI in both 3.5% NaCl and 20% H_2SO_4 solutions. In particular, an interlayer of 25 μm EN between TiN coating and ADI substrate exhibits the best corrosion resistance.

並列關鍵字

Austempered ductile iron ； Electroless nickel ； TiN ； Corrosion resistance