【摘要】 在微米Si₃N₄基体中加入纳米Si₃N₄及TiC颗粒,以Al₂O₃和Y₂O₃作为助烧结剂,通过热压烧结制备了Si₃N₄/TiC纳米复合陶瓷刀具材料,研究了该材料在800～1250℃时的氧化行为。结果表明:该类材料的氧化特性符合抛物线规律;随TiC含量的增加,材料的抗氧化性能降低。由氧化后样品的X射线衍射谱分析可知:氧化表面生成SiO₂和TiO₂,表面仅余微量的Si₃N₄和TiC成分,表明经1250℃,100 h氧化后,样品表面几乎被氧化物覆盖。Si₃N_/TiC（含有10%纳米Si₃N₄和15%TIC,质量分数）纳米复合材料在经过900℃,100h氧化后,其强度无明显下降;但经过1 000℃,100h的氧化后,材料的强度已经降至氧化前的41%。扫描电镜观察表明裂纹的生成及扩展是引起强度降低的主要原因。更多还原

【Abstract】 Si₃N₄/TiC nanocomposite ceramic tool materials were fabricated by adding Si₃N₄ and TiC nanoparticles and with Al₂O₃ and Y₂O₃ as additives.The oxidation behavior of Si₃N₄/TiC nanocomposite ceramic tool materials in the temperature range of 800-1250℃was studied.The results show that the relationship between oxidation mass gain and oxidation time obeys the parabolic law.The oxidation mass gain increases with the increase of content of TiC.The composition of the surface layer of the materials after oxidation were investigated with X-ray diffraction.The results indicate that the surface oxidation layer is constituted of SiO₂ and TiO₂,and only a little Si₃N₄ or TiC phase can be found in the oxidation surface layer.This indicates that the surface layer is significantly covered with oxides after oxidation at 1250℃for 100h.There was no obvious decrease of bending strength of the 85%（in mass,with 15% nano-Si₃N₄）Si₃N₄/15% TiC sample after oxidation at 900℃for 100h,whereas the strength after oxidation at 1000℃for 100h decreases to 41% of the strength before oxidation.Scanning electron microscope observation indicates that the initiation and exten- sion of cracks are the main reasons for the decrease of strength.更多还原