摘 要
本研究主要是針對延性鑄鐵進行沃斯回火熱處理使之成為沃斯回火延性鑄鐵(ADI)基材，表面處理則是先利用電鍍銅當作中介層(25μm)，再施以陰極電弧披覆TiAlN薄膜(3μm)，然後進行後熱處理及各種腐蝕試驗(極化試驗、浸泡試驗及鹽霧試驗)，用以探討經後熱處理後其對複合表面鍍膜ADI耐腐蝕性之影響。
實驗結果顯示，ADI基材經複合鍍膜(電鍍銅與電弧披覆TiAlN)及後熱處理均不會劣化基材，具有優異的顯微組織，且複合鍍膜的附著性佳，經後熱處理亦不會影響鍍膜的附著性。在表面硬度方面，複合鍍膜可明顯提高ADI的硬度。在腐蝕方面，經過極化試驗、鹽霧試驗及浸泡試驗結果可知有中介層(電鍍銅)的薄膜比沒中介層的薄膜較耐腐蝕，推斷中介層有緩和腐蝕媒介物直接進入基材達到保護作用，而經後熱處理後，因有CuO的析出，反而造成鍍膜層耐腐蝕性略下降。
關鍵詞：沃斯回火延性鑄鐵、氮化鈦鋁鍍膜、電鍍銅、後熱處理、耐腐蝕
ABSTRACT
In this study, the ductile iron was treated with austempering heat treatment to become as austempered ductile iron (ADI) substrate. The surface treatment was to first use electroplating copper as the intermediary layer (25 μm), and then apply the cathodic arc deposition to coat the TiAlN film (3 μm). Then the post heat treatment and various corrosion tests (polarization test, immersion test, and salt spray test) were conducted to explore the effect of post heat treatment on the corrosion resistance of composite surface coated ADI.The experimental results showed that the ADI after composite coating (copper electroplating and arc coating TiAlN) and post heat treatment could not degrade the excellent microstructure of the substrate. The composite coatings had good adhesion, and post heat treatment could not affect the adhesion of the coatings. In terms of surface hardness, composite coating could significantly increase the hardness of ADI. In terms of corrosion, after polarization test, salt spray test and immersion test, it is found that the TiAlN film with the Cu interlayer is more resistant to corrosion than that without the interlayer. It is inferred that the interlayer has a mitigating corrosion agent that directly enters the substrate to achieve protection. After the post heat treatment, the corrosion resistance of the coatings is slightly reduced due to the precipitation of CuO.
Keywords: Austempered ductile iron, TiAlN film, Electroplating copper, Post heat treatment,
Corrosion resistance
