鎂及其合金在實用金屬中已廣泛被使用在航空、汽車及3C產品上，由於其優點：比剛性高、制震能良好，加工性優良、電磁波遮蔽性佳及導熱性高。是對於運輸交通工具、隨身攜帶式資訊產品等3C產品更加輕量化的關鍵材料。然而鎂合金在大氣環境中為化學活性高之金屬，抗腐蝕性較差。為提升其實用性，各界於其表面抗腐蝕處理的研究在鎂金屬表面上沉積金屬、陶瓷與複合式薄膜來提升抗腐蝕能力。本研究使用常壓電漿輔助化學氣相沉積(APPECVD)氧化矽薄膜來提升其抗腐蝕能力，藉由改變載氣氣體流量並加以後續熱處理來探討流量變化及熱處理前後對於薄膜形貌、組成及性質之影響。
材料分析方面利用水滴接觸角量測儀(Contact Angle Goniometer)觀察其親疏水性及表面能，表面形態則以場發射掃描式電子顯微鏡(Field Emission Scanning Electron Microscope, FE-SEM)與原子力顯微鏡鏡(Atomic Force Microscope, AFM)進行觀察，並以傅立葉紅外線光譜分析儀(Fourier Transform InfraRed Spectroscopy)及化學分析電子能譜儀(Electron Spectroscopy for Chemical Analysis, ESCA)鑑定表面官能基與化學鍵結之組成，以場發射雙束型聚焦離子束顯微鏡(Dual Beam Focused Ion Beam, FIB)切試片剖面觀察其沉積之薄膜厚度，最後，將所有試片置於3.5 wt% NaCl水溶液中，利用電化學方法探討各種不同載氣流率所生成的二氧化矽薄膜及熱處理前後之電化學腐蝕行為。
實驗結果顯示，氧化矽薄膜的表面自由能較原始AZ31較小，從60 mN/m下降至45 mN/m，可以得到較疏水的效果。並且由AFM及SEM觀察得知，氧化矽薄膜的均勻性及平坦性相當良好，總體粗糙度平均約3~5 nm，隨著載氣氣流量改變，其形貌不是呈一線性規則變化，且在900 sccm的製程可以發現特殊的有序排列現象，視為一轉折點。藉由化學分析電子能譜全譜圖可以發現氧化矽薄膜組成為Si、C、O三種元素，並無其他元素產生，且O/Si 比例接近2。經由剖面圖可以觀察到氧化矽薄膜厚度約為90 nm，其沉積速率約為210 nm/min，在電化學極化曲線可以發現，本實驗製備的氧化矽薄膜於AZ31鎂合金上有優異的抗腐蝕效果，腐蝕電流密度(icorr)由2.40×10-1 /mA cm-2下降3~5個級數。最後，試片經過熱處理300°C /2hr後，其表面更為緻密，然而卻產生微小之間隙、孔洞，代表其薄膜有組成上的改變，藉由傅立葉紅外線光譜儀證實表面上之hydroxyl group或CHx group被移除，其腐蝕電流密度(icorr)更下降至9.00×10-6 mA cm-2，然而其孔蝕因子也造成氧化矽薄膜抵抗腐蝕效果受到影響。

Magnesium alloys have been widely used in the aircraft and automobile industries because of many advantages of low density, high strength/weight ratio, excellent machinability and recyclability. Unfortunately, it has a major drawback due to the poor corrosion resistance that restricts their engineering applications. In general, traditional surface treatments by wet processes (electrochemical plating, anodizing, and micro-arc oxidation) and dry processes (thermal spraying, chemical vapor deposition, and physical vapor deposition) are necessarily required to improve the corrosion resistance of magnesium alloys. However, these processes are not environmentally benign or needed to be equipped with the vacuum systems.
This study is to evaluate the feasibility and application of silicon oxide (SiOx) thin films as anti-corrosion layers for AZ31 magnesium alloys by atmospheric pressure plasma enhanced chemical vapor deposition (APPECVD). The effects of carrier gas flow rates was investigated for the SiOx film deposition. The surface morphologies of deposited SiOx film were examined by Contact Angle Goniometer, Atomic Force Microscope (AFM) and Field Emission Scanning Electron Microscope (FE-SEM). The chemical compositions were analyzed by Fourier Transform InfraRed Spectroscopy (FTIR) and Electron Spectroscopy for Chemical Analysis (ESCA). The corrosion resistance of Mg alloy and SiOx film was evaluated using potentiodynamic polarization measurements in 3.5 wt% NaCl solutions.
The results show that surface free energy of the deposited SiOx was lower than Mg alloy, which resulted in a more hydrophobic surface to avoid getting wet and being corroded. The surface morphology of SiOx films were uniformly smooth with a root mean square about 3~5 nm. The surface morphologies of SiOx films from SEM observation randomly altered with increasing the O2 carrier gas flow rates. According to the results of FTIR and ESCA, the chemical compositions of SiOx films were composed of silicon, oxygen, and carbon, and O/Si ratio were close to 2. It can be found that the thickness of SiOx films were about 90 nm and the deposition rate were 210 nm/min. After corrosion test by the potentiodynamic polarization measurements in 3.5 wt% NaCl solutions, the anticorrosion behavior of SiOx film on AZ31 deposited at tge carrier gas flow rate of 1500 scccm was evidently proved with a higher corrosion potential (Ecorr = -1392 mV) and a lower corrosion current (Icorr.= 5.30×10-4 mA cm-2) as compared to raw AZ31 materials (Ecorr = -1463 mV；Icorr .= 2.40×10-1). For thermally treated at 300°C for 2hr, the tiny pits and nanopores were observed at the surface of fillms due to the removal of hydroxyl group and CHx group analyzed by FT-TR, which altered the corrosion behavior of SiOx film on AZ31.

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