Hydrogen Analysis by Using of Secondary Ion Mass Spectroscopy

(1)氢分析用二次离子质谱（西姆斯）对注入质子的标准样品（SiO_2/Si）进行了氢分析，确定了氢分析的最佳分析条件。离子束的光栅尺寸、中和、信号选通等控制是氢分析的重要环节。(2)湿氧化速率用热重法测定了化学气相沉积碳化硅（CVD-SiC）和氮化硅（CVD-Si_3 N_4）的湿氧化速率。用XRD和拉曼光谱对氧化膜进行了分析。氧化速率随大气中水蒸气压的增加和氧气压的降低而增加。这可能是由氧化膜（二氧化硅）中的微缺陷的变化引起的。大气中的水蒸气在较低温度（约1373 K）时促进氧化膜的晶化，在较高温度（>1873 K）时促进氧化膜的非晶化。激光拉曼光谱表明，氧化物/气体界面附近为无定形二氧化硅，氧化物/陶瓷界面附近为方石英，形成的氧化膜是双层膜。这些结果表明，非晶二氧化硅的形成降低了硅基陶瓷的抗氧化性的湿氧化。

(1) Hydrogen analysisHydrogen analysis by using of secondary ion mass spectroscopy (SIMS) was carried out for the standard sample (SiO_2 on silicon) in which proton was implanted, and the optimum analytical conditions for hydrogen analysis were clarified. It is important for hydrogen analysis to control the raster size of an ion beam, neutralization, signal gating and so on.(2) Wet oxidation rateWet oxidation rates of chemically-vapor-deposited silicon carbide (CVD-SiC) and silicon nitride (CVD-Si_3N_4) were measured by a thermogravimetric technique. The oxidation films were analyzed by XRD and Raman spectroscopy. The oxidation rate was increased with increasing of water vapor pressure and decreasing of oxygen pressure in the atmosphere. This may be lead by the change of micro-defects in the oxide film (silica). Water vapor in the atmosphere accelerated the crystallization of oxide film at lower-temperatures (around 1373 K) and non-crystallization at higher-temperatures (>1873 K). It was clarified by laser Raman spectroscopy that amorphous silica was at around oxide/gas interface and cristobalite was at around oxide/ceramics interface, i.e., the oxide film formed was a duplex one. These results suggested that the formation of amorphous silica lowered the oxidation resistance of siliconbased ceramics for wet oxidation.