CENA1模具鋼軟氮化/DLC鍍膜之研究

CENA1預硬鋼是塑膠射出模具用鋼，具有優良的鏡面加工性及拋光性，其硬度大約只有HRC37-42 (約HV360-410)，當應用在模具的模仁或模穴材料時，其耐磨耗性顯然不足。本研究於CENA1材料表面施以兩種軟氮化處理：(1)氣體軟氮化法，(2)鹽浴式滲硫氮化法(Sursulf Process)，兩種氮化後之試片表面繼續披覆一層類鑽碳薄膜(DLC)。經由SEM, 磨耗試驗，表面粗度分析，水接觸角試驗，耐腐蝕試驗，拉曼實驗分析等，比較兩種氮化處理與披覆類鑽碳薄膜後之表面特性。實驗結果顯示，經氣體軟氮化、鹽浴式滲硫氮化處理後，其表面硬度值分別提升到HV480、HV536。而鹽浴試片表面粗糙度值為0.584 μm，較基材0.472 μm高，導致鹽浴/類鑽碳薄膜之試片附著性降低，只有HF6之等級。而氣體軟氮/類鑽碳薄膜之試片有達到HF4之等級。從拉曼實驗分析得知，其ID/IG值約為0.859，這個值接近石墨組織(sp2鍵結比例增加)，因此會降低摩擦係數與磨耗率。

關鍵字

氣體軟氮化；鹽浴式滲硫氮化；類鑽碳薄膜；耐腐蝕試驗；磨耗試驗；拉曼試驗

並列摘要

CENA1 prehardened steel was used for plastic injection mold. This material has excellent mirror machinability and polishing feature. CENA1 has low hardness of HRC37~42 (HV360-410). Its wear resistance is not appropriate for core or cavity in the molds. In this study, CENA1 was treated by two nitrocarburizing methods: gas nitriding process, and Sursulf process. These samples were then deposited with diamond-like carbon (DLC) films after nitriding process. Surface morphology, surface roughness test, wear test, water contact angle test, corrosion test, and Raman analysis were used to analyze the coatings. Result show that surface hardness increases to HV480 and HV536 after gas nitriding and Sursulf treatment. However, the Sursulf treated surface bears 0.584 μm roughness which is higher than that of CENA1 substrate. This also leads to the decrease of adhesion (level HF6). On the other hand, the gas nitriding + DLC deposited coatings has the level of HF4. Raman analysis showed that ID/IG is about 0.859. This value is characteristics of graphite structure with increased sp2 bond ratio which decreases the coefficient of friction and thus the wear rate.