The effect of Ti and TiO2 additions on the pressureless sintering of B4C
The effect of Ti and TiO2 additions on the pressureless sintering of B4C
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DOI：
10.1007/s11661-999-0230-6
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发表时间：
1999-12
期刊：
影响因子：
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通讯作者：
L. Levin;N. Frage;M. Dariel
中科院分区：
文献类型：
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作者：
L. Levin;N. Frage;M. Dariel
在1800 ~ 2190℃的温度范围内，研究了tio2和Ti添加量对B4C烧结性能的影响。根据经实验结果验证的热力学预测，tib2是在两种情况下形成的。氧化钛会被B4C中的碳还原，从而降低其含碳量。随着碳含量的降低，碳化硼相中碳的活性显著降低。在2160℃下烧结1小时，细粒度B4C和40% tio2的混合物转变为95%致密的两相复合材料，该复合材料由亚化学量碳化硼和tib2组成，其弯曲强度为420 MPa。这种复合陶瓷的烧结性能显著改善是由于在亚化学计量B4C中发生的质量传递过程的增强。亚化学计量B4C的低碳活度值确保与熔融金属反应时不会产生有害的碳化物相。
The effect of TiO2and of Ti additions on the sintering behavior of B4C was studied in the 1800 °C to 2190 °C temperature range. According to thermodynamic predictions that were verified by the experimental results, TiB2is formedin situin both instances. Titanium oxide is reduced by carbon that originates in B4C and decreases its carbon content. The activity of carbon in the boron carbide phase is reduced significantly with decreasing carbon content. By sintering at 2160 °C for 1 hour, a mixture of fine-sized B4C with 40 wt pct TiO2is transformed into a 95 pct dense two-phase composite that consists of substoichiometric boron carbide and TiB2and displays a bending strength of 420 MPa. The significantly improved sintering behavior of this composite ceramic is attributed to the enhanced mass transport processes that takes place in substoichiometric B4C. The low carbon activity values in substoichiometric B4C ensure that no deleterious carbide phases are produced by reaction with molten metals.