A Study on process parameters and properties of deposited Cr and Al containing diamond-like carbon film by unbalanced magnetron sputtering

[[abstract]]本研究以PCB 銑刀材料－高速鋼為實驗基材，利用非平衡磁控物理濺鍍系統 於基材表面被覆一添加鉻、鋁金屬之類鑽碳膜，以期解決類鑽碳膜附著力不佳之 問題，並使薄膜可應用於耐高溫氧化及耐磨耗之環境，以因應高精密、高速連續 切削且不添加切削液之使用需求。 本文主要分為三大部分： 1. 田口實驗法尋找最佳製程參數。 2. 探討各製程參數對薄膜性質之影響。 3. 薄膜高溫性質之分析。 於薄膜性質檢測方面，使用Raman、FE-SEM、EDS、GDS、TGA、OM、微 硬度計、表面3D 輪廓儀、刮痕試驗、磨耗試驗等設備及試驗以分析薄膜性質，其 結果顯示： 本研究利用田口實驗法求得之最佳製程參數為：鉻靶電流2.5 A、鋁靶電流2 A、乙炔流量12 sccm、基板偏壓-50 V、氬氣流量20 sccm、脈衝頻率40 KHz、濺 鍍時間120 mins，其所濺鍍含鉻鋁金屬類鑽碳膜之摩擦係數為0.18，且薄膜附著 力可達62.13N。 ii 本研究所濺鍍之含鉻鋁金屬類鑽碳膜呈柱狀晶結構，薄膜主要組成為sp2、sp3 相及碳化鉻（Cr3C2 及 Cr7C3）之相。以本研究所得之最佳製程參數為中心條件下， 探討不同製程參數對薄膜性質之影響，其結果顯示：（1）當濺鍍距離為6~8 cm 及 濺鍍時間介於80 ~ 120 mins 時，薄膜附著力可達60N，且耐磨耗性亦符合需求；（2） 另薄膜中鋁含量與薄膜硬度及附著力成反比之關係，本研究中薄膜鋁含量應低於 14.3wt%方可得較佳之薄膜耐磨耗性；（3）當乙炔含量為9~12 sccm 時，薄膜具有 類鑽碳膜之特性，可降低薄膜摩擦係數並提升薄膜之耐磨耗性；（4）基板偏壓為 -100V 時，薄膜耐磨耗性為最佳。 在薄膜高溫性質方面，考量薄膜耐磨耗性、附著力、時間成本及熱變形之整 體因素，以本研究所得之最佳製程參數濺鍍之含鉻鋁金屬類鑽碳膜，於600℃大氣 環境中，適合之熱處理時間為30 分鐘。又薄膜經600℃以上熱處理後，薄膜會析 出Cr3C2 及C7C3 相，並在表面生成Al2O3 及Cr2O3 氧化膜，可提昇薄膜硬度、耐磨 耗性及耐高溫性質。另薄膜經600℃熱處理時，其附著力略升至68.47N，然而， 當薄膜經700℃以上溫度熱處理時，薄膜因組成相之熱膨脹係數差異影響，導致加 熱後薄膜附著力不佳，總而言之，以本研究所得最佳製程參數所濺鍍之含鉻鋁金 屬類鑽碳膜，其薄膜摩擦係數為0.18，薄膜附著力可達62.13N，且薄膜可應用於 600℃之高溫環境。[[abstract]]Abstract In this study, the high-speed steels were used as the substrates for sputtering. Cr and Al containing diamond-like carbon films deposited by unbalanced magnetron sputtering to improve the adhesion of diamond-like carbon film as well as high-precision, high-speed and continuous dry cutting in high-temperature environment. The three main subjects in this study are as follows: 1. To find the optimum process parameters by Taguchi Method. 2. To study the effect of main process parameters on the properties of films. 3. To analyze the high-temperature properties of films. We used the Raman、FE-SEM, EDS, GDS, TGA, OM, Vickers’ microhardness, 3D iv surface profile tester, scratch and wear test to characterize the properties of films. The results are as follows： The optimum process parameters obtained by Taguchi method were as follows： ♦ Cr target current = 2 A ♦ Al target current = 2 A ♦ C2H2 flow rate = 12 sccm ♦ Bias voltage = -50 V ♦ Argon flow rate = 20 sccm ♦ Pulse frequency = 40 KHz ♦ Deposition time = 120 minutes. Also, the wear coefficient of the Cr and Al containing diamond-like carbon film deposited by optimum parameters is 0.18 and its adhesion can reach 62.13N. Cr and Al containing diamond-like carbon films in this study exhibit the fine columnar grain microstructure and are composed of sp2, sp3, Cr3C2, Cr7C3 and some amorphous phase. Furthermore, we also found some results in effect of different process parameters on the properties of films such as： (1) The film adhesion can reach 60N and has good wear resistance when the deposition distance is 6 ~ 8 cm and deposition time is between 80 ~ 120 minutes. (2) When Al content of the film increase, the film hardness and adhesion will decrease. The Al content of the film in this study shall be lower than 14.5 wt% in order to get the better wear resistance. v (3) The films have DLC properties to reduce the wear coefficient and to improve the wear resistance when the C2H2 flow rate is 9 ~ 12 sccm. (4) The film has the best wear resistance when the bias voltage is equal to -100V. In high-temperature properties of films, the applicable heat treatment time is equal to 30 minutes in 600℃ high-temperature environments with considering the wear resistance and the adhesion of films, time cost and heat deformation. Also, after annealing above 600℃, the Cr3C2 and C7C3 phases were precipitated and a dense protective film of complex Cr2O3 and Al2O3 oxides was formed on the film surface for better hardness, wear resistance and high temperature properties of films. Besides, the adhesion of film was slightly increased from 62.13N to 68.47N by annealing at 600℃. However, the adhesion of film was worse by annealing above 700℃ due to the large variation in coefficient of thermal expansion of composing phases. In conclusion, the Cr and Al containing diamond-like carbon films deposited by optimum process parameters obtained by Taguchi method have low wear coefficient of 0.18 and high adhesion of 62.13N, so the film can be applied in a high-temperature condition of 600℃