摘要
采用超重力下燃烧合成工艺,可以制备出大体积凝固态碳硼化物基共晶复合陶瓷,同时为抑制TiC-TiB2复合陶瓷的热裂倾向,在制备过程中加入一定量的WO3作为铝热反应的氧化剂之一,通过燃烧合成获得Ti-W-Cr-C-B合金液相,进而制备出低缺陷、高致密性的TiB2-(Ti,W)C共晶复合陶瓷。XRD、FESEM与EDS结果显示,陶瓷基体主要由TiB2-(Ti,W)C共晶组织构成,且在基体边界上存在少量的Al2O3和Al2O3-ZrO2共晶组织。由于超重力诱发反应熔体内部分层,导致熔体中液态氧化物浮于熔体上层,而Ti-W-C-B合金液相则位于熔体下部,最终凝固生成TiB2-(Ti,W)C复合陶瓷。由于W/Ti无限互溶,W原子向TiC中扩散,在TiC中形成了(Ti,W)C固溶体,(Ti,W)C固溶体完全保持了TiC的晶格结构。性能测试表明,TiB2-(Ti,W)C共晶复合陶瓷的相对密度、硬度和断裂韧度均较高,分别为98.4%、26.4GPa和7.6MPa.m1/2。
Large bulk solidified TiC-TiB2 eutectic composite ceramics were prepared by combustion synthesis under high gravity,and the WO3 was introduced into the combustion synthesis as one of oxidants in the thermit to obtain liquid Ti-W-Cr-B phase,as a result,near-full-density TiB2-(Ti,W)C eutectic composite ceramic with macrocrack free were successfully prepared.XRD,FESEM and EDS results show that the ceramic matrix is mainly composed of TiB2-(Ti,W)C eutectic structure with a little of Al2O3 and Al2O3-ZrO2 eutectic structure existed at boundary.By introducing high gravity,Stocks immigration of immiscible liquid is taken place due to their density difference,resulting in float-up of oxide liquid and settle-down of Ti-W-Cr-C-B liquid,and the layered melt consisting of oxide liquid and Ti-W-Cr-C-B liquid is formed,finally,TiB2-(Ti,W)C eutectic composites grows from the melt.Due to the mutual solubility of W-Ti,the W atom can be diffused into the TiC,resulting in the formation of (Ti,W)C solid solution with the crystal lattice structure as the same as TiC.Relative density,Vickes hardness and fracture toughness of the composites reach up to 98.4%,26.4GPa and 7.6MPa·m1/2,respectively.
出处
《特种铸造及有色合金》
CAS
CSCD
北大核心
2010年第7期664-667,共4页
Special Casting & Nonferrous Alloys
基金
国家自然科学基金资助项目(50672131)
