- 學位論文
陰極電弧沈積Cr(N,O)/CrN複合鍍膜之氧化與腐蝕行為研究
Oxidation and Corrosion Behaviors of Cr(N,O)/CrN Duplex Coatings Synthesized by PVD-CAE Process
摘要
陰極電弧沈積（Cathodic Arc Evaporation, CAE）技術，是物理氣相沈積（PVD）技術之一，由於其鍍膜速度較快、附著性良好及品質較優良等等，藉由此技術在工具鋼、模具鋼或其他硬質合金上，披覆超硬薄膜，可提升模具的使用壽命，故近年來已成為普遍的加工方式。硬質薄膜的種類繁多，氮化鈦（TiN）、氮化鋁鈦（TiAlN）類碳鑽（DLC）及氮化鉻（CrN）等等，則是目前較常被使用的材料。 CrN鍍膜之所以具有高硬度、高溫抗氧化性、低摩擦係數、耐蝕及耐磨耗等特性，主要原因是來自於表面容易生成氧化鉻（Cr2O3）所致。然而，在一些應用上，CrN的硬度因仍不及TiN或TiAlN高，使得CrN提早磨損，工作壽命遜於其他硬質薄膜。因此基於CrN和Cr2O3的相互關係，本研究則是直接利用陰極電弧系統，以變化氧氣流量參數來披覆Cr(N,O)/CrN複合鍍膜，探討藉由此製程參數的變化以尋求最佳參數，並進行不同製程之鍍膜型態的觀察以及氧化及腐蝕行為等研究，可提供學術上或工業上應用之參考。 實驗結果顯示，利用陰極電弧系統沈積的Cr(N,O) / CrN複合鍍膜，經X-ray及XPS成份鑑定後，發現成份幾乎一樣，但比較Cr(N,O) / CrN複合鍍膜之膜厚測量發現，氧氣會使靶材產生毒化的現象，導致沈積率的下降；在奈米硬度試驗中，當通氧量達69sccm（S3）時，其硬度值高達25.6GPa，其餘試片也都高達18GPa以上，但還是不及DLC之硬度值35.5GPa；由氧化試驗中得知，Cr(N,O)/CrN複合鍍層之氧化起始溫度，除了通氧量0sccm(CrN)為776.9℃之外，其餘皆可達到820℃以上，但是氧化後之表面結構則變為C-Cr-O之化合物，而DLC之氧化起始溫度則為300℃，而且Cr(N,O)/CrN複合鍍層在800℃之氧化速率都較DLC低；由極化試驗中可知，Cr(N,O)/CrN複合鍍層之抗極化性與DLC差不多，而由浸蝕試驗中可知，基材(SKH51)及Cr(N,O)/CrN複合鍍層和DLC對Cl-之抗蝕性比對H+好，而且在鹼性溶液中不易受侵蝕。
並列摘要
Cathodic arc evaporation (CAE) process is one of the physical vapor deposition processes. To increase the efficiency of cutting, tool materials and their geometry are continually being improved. In particular, better cutting performance was obtained by the introduction of thin hard coating on tools. Due to its high rates of the deposition, well adhesion, and superior quality ... etc, it has become the normal processing in these years. There are various kinds of hard thin films, as TiN, TiAlN, DLC, and CrN… etc, which is the common used materials in nowadays. CrN with excellent properties in hardness, oxidation resistance, chemical stability and slid comes from the easily formed Cr2O3 on the surface. Compared with TiN, the oxidation resistance of CrN is higher since the Cr oxide film formed at high temperature is more stable than that of Ti. The purpose of this study was to deposit Cr (N,O)/CrN duplex coating on SKH51. The structural, mechanical, oxidation and corrosion properties will be discussed. As shown in the experiment, during the CAE process, input oxygen will poison the target, leading to the increase of the electrical resistance and the decrease of the deposition rate. Therefore, at the same time the film thickness of CrN is thinnest. In hardness experiment, when the input of oxygen is 69sccm (S3), it can get the highest hardness, 25.6Gpa, and the hardness of the others conditions could also reach the value of 18Gpa, but they are still lower than that of DLC. During oxidation experiment, the start oxidation temperature of double-layered Cr(N,O)/CrN are higher than 820℃, besides that of the input of oxygen 0sccm(CrN) is 776.9℃, and the structure will become the compound of C-Cr-O. During polarization experiment, it can be seen that the polarization resistance of the double-layered Cr(N,O)/CrN are similar to DLC. In immersion experiment, erosion resistance of the substrate (SKH51), the double-layered Cr(N,O)/CrN, and DLC to Cl- is better than to H+, and they all will be corrode with alkaline solution difficultly.