Mechancical Properties and Corrosion of DLC Films by PVD and PECVD Process

• Main Authors: Chao-Hsiang Chang, 張朝翔
• Other Authors: 張銀祐
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/yymscp

碩士 === 國立虎尾科技大學 === 機械與電腦輔助工程系碩士班 === 102 === Diamond-like carbon (DLC) thin films, which are usually black, are used for decorative applications because of their good corrosion-resistance and chemical inertness. In this study, we used a physical vapor deposition (PVD) to prepare a Cr-C film, while we used a plasma enhanced chemical vapor deposition (PECVD) to prepare DLC films. At the same time, a composite film consisted of Cr-C and DLC (Cr-C+DLC) was depositedfor comparison. The microstructureand surface morphologies of the deposited coatings were analyzed using SEM, TEM and AFM. The chemical composition and bonding structure were analyzed using X ray photoelectron spectroscopy (XPS). A nanoindentation was used to measure the film hardness and Young''s modulus of the deposited coatings. To identify the corrosion resistance of the deposited coatings, the samples were put in a 3.5% NaCL solution using a potentiostat. According to the TEM results, we found the deposited Cr-C and DLC films were amorphous. The interface near the substrate of the Cr-C film was orthogonal structure of Cr_7 C_3(051). It showed that the DLC film deposited by PECVD is the densest among the deposited coatings. According to the results of XPS and nanoindentation, The DLC layer of the Cr-C+DLC composite film showed graphitization, and the hardness of this coating is reduced. When DLC was add onto the Cr-C film, the L values reduced from 43.08 (Cr-C) to 37.09, and showed more black. From the Four Point Probe results, it showed that the resistances of the deposited Cr-C film, DLC and Cr-C+DLC’s value were near zero Ω, 2×〖10〗^6 Ω and 5×〖10〗^4Ω, respectively. The potentiostatic results showed that the corrosion potentials of the deposited Cr-C, DLC and Cr-C+DLC were -0.109 V, 0.082 V and 0.455 V, respectively. The corrosion resistance R_p of the Cr-C , DLC and Cr-C+DLC were, 1.21×〖10〗^8 (Ω/cm^2), 9.14×〖10〗^8 (Ω/cm^2), 1.04×〖10〗^9 (Ω/cm^2)respectively. It showed that the composite Cr-C + DLC film had the highest corrosion potential and polarization resistance.