以陰極電弧離子鍍著氮化鉻鍍膜之高溫氧化行為

Oxidation of The Arc Ion-plated CrN Coatings at Elevated Temperatures

本研究是以X光繞射分析儀（XRD）、掃描式電子顯微鏡（SEM）、穿透式電子顯微鏡（TEM）和歐傑電子能譜儀（AES）探討CrN薄膜在300℃到800℃的溫度範圍於空氣中氧化60分鐘的特性。CrN薄膜是利用陰極電弧沈積技術沈積在具有鉻中間層的304不銹鋼上。XRD結果顯示CrN薄膜鍍著的不鏽鋼在高於500℃溫度以上會產生Cr2O3和β-Cr2N兩個相，且兩者的含量隨著氧化溫度升高而增加。氧化溫度在600℃以上的試片，經由SEM觀察出薄膜表面形貌有顯著的變化。橫截面TEM影像顯示出鍍著氮化鉻的試片，經高溫氧化後於鍍膜表面生成一氧化鉻層，其下方為CrN與β-Cr2N兩相混合層。與剛鍍著的試片不同的是，氧化後試片中的混合層具有等軸晶結構，且晶粒尺寸亦隨氧化溫度升高而成長。由不同氧化溫度之歐傑電子縱深分析得知元素分佈，且利用其結果換算出不同溫度之氧化鉻厚度，亦由此引出氧化鉻氧化的活化能為1.63eV。

Characterization of the CrN coatings oxidized in air at temperatures ranging from 300℃ to 800℃ for 60 min was carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Auger electron spectroscopy (AES). The CrN coatings were prepared by cathodic arc ion plating deposition on a type 304 stainless steel with a Cr interlayer. The XRD results show that oxidation of the CrN-coaled steel above 500℃produces two new phases, Cr2O3 and β-Cr2N, and the amount of both phases increases with the oxidation temperature. A noticeable change in the surface morphology of the coatings were observed by SEM in the specimens oxidized at temperature above 600℃. Cross-section TEM reveals that oxidation of the CrN-coated steel at high temperatures produces an oxide layer, Cr2O3, on the coating surface, and the underlayer is a mixture of CrN and β-Cr2N phases. Unlike the as-deposited specimen, the dual phase layer in the oxidized specimens has an equiaxed grain structure and the average grain size of the layer increases with the oxidation temperature. Depth profiling of the oxidized CrN coatings at various temperatures by AES gives the elemental distributions near the free surface, and the activation energy for oxidation of the CrN coatings was calculated to be 1.63 eV.