Abstract: The changes of the properties and microstructure of carbon fibers made in our laboratory were studied in strong oxidation agents，including concentrated nitric acid and the mixtures of concentrated sulfuric acid and concentrated nitric acid. The results showed that when carbon fibers were oxidized by concentrated nitric acid，tensile strength of carbon fibers increased more than that of the untreated sample，meanwhile modulus had little change. When the carbon fibers are oxidized by the mixture，the strength and the modulus of carbon fibers decreased with the increase of oxidation time，and decreased rapidly with the increase of volume fraction of concentrated sulfuric acid. Results of XRD suggested that oxidation of concentrated nitric acid affect the microstructure size in the direction paralleled to fiber axis，and oxidation of concentrated sulfuric acid had effect on that in the lamellar stacking direction of carbon fibers.

Key words: carbon fibers, oxidation, tensile strength, microstructure, carbon fiber, oxidation, tensile strength, microstructure

摘要： 以实验室自制碳纤维为原料，研究了碳纤维在浓HNO3及不同浓度的浓H2SO4/浓HNO3强氧化介质中的性能与结构变化。结果表明，浓HNO3单独氧化时，碳纤维强度较未处理前有所增加，模量变化不大；在浓H2SO4和浓HNO3的共同氧化作用下，碳纤维强度和模量均随着处理时间的延长不断下降，且随着浓H2SO4体积分数的增加下降加快。XRD分析结果表明，浓HNO3的氧化作用主要影响平行于纤维轴向的微观尺寸，而浓H2SO4的氧化主要在纤维的片层堆叠方向起作用。

关键词: 碳纤维, 氧化, 拉伸性能, 微观结构, 碳纤维, 氧化, 拉伸性能, 微观结构