【摘要】 研究了热压碳化硼在 973～ 12 73K的氧化行为及其对摩擦性能的影响 .氧化试样用X射线衍射分析其成分 ,用电子显微镜观察其微观形貌 .结果表明 ,氧化试样表面生成一层薄而透明的B2 O3液膜 .由于B2 O3与B4C材料的热膨胀系数相差甚远 ,因而冷却时发生龟裂 .B2 O3继而与空气中的水蒸汽发生反应 ,生成白色的H3BO3.H3BO3是一种固体润滑剂 ,当其出现于碳化硼摩擦副表面 ,可将摩擦系数由未经氧化处理的B4C/B4C摩擦副的 0 .2 5～ 0 .3 5降至 0 .0 5左右 .但氧化温度达 12 73K时 ,由于表面氧化腐蚀较严重 ,可能造成表面颗粒剥落 ,不利于降低摩擦系数 .更多还原

【Abstract】 The oxidation behavior under 973—1 273 K and the effect of oxidation on the room_temperature tribological properties of hot_pressed boron carbide ceramic were investigated. Oxidized samples were studied by X -ray diffractometer and scanning electron microscopy. It is demonstrated that the oxidation results in the formation of a thin transparent B 2O 3 film, and the oxide film is severely cracked during cooling due to the thermal expansion mismatch between the oxide film and the B 4C substrate. B 2O 3 reacts with moisture in the air to form boric acid, which is a kind of solid lubricant. The sliding friction coefficients of oxidized B 4C pair are about 0.05—0.08, compared to 0.25—0.35 of the as_received B 4C pair. When the temperature is up to 1 273 K, a significant increase in friction coefficient is observed, as the friction interface is roughened by severely etching of grain boundaries.更多还原