挤出成型碳化硅陶瓷的力学性能和显微结构

以羟丙基甲基纤维素（HPMC）作为有机塑化剂, 采用挤出成型工艺常压烧结制备碳化硅陶瓷管材, 系统研究了羟丙基甲基纤维素含量对陶瓷管材性能的影响以及不同温度制度下碳化硅陶瓷显微结构变化. 研究结果表明, 陶瓷管材坯体的平均径向抗外压强度随着HPMC含量的增加呈增加趋势, 当HPMC含量为7.5wt％时达462MPa; 2200℃保温1h烧结陶瓷管材的致密度随着HPMC含量的改变没有明显的变化. 采用两步烧结法得到的碳化硅管材体积密度从3.00g/cm³增加到3.07g/cm³, 平均径向抗外压强度达540MPa, 致密度可达95.9%. 抛光面经化学腐蚀后的显微结构表明碳化硅颗粒出现异常长大, 有部分板状晶粒出现.

Mechanical Properties and Microstructure of Extruded SiC Ceramics

Silicon carbide tube was extruded and pressureless-sintered using hydroxypropyl methylcellulose (HPMC) as the main organic plasticizer. The effect of HPMC contents on the properties of the sintered SiC tubes and the microstructure evolution in the different sintering system were systematically studied. The results show that the radial crushing strength of SiC green bodies increases with increasing HPMC content while the average radial crushing strength obtain maximum of 462MPa with 7.5wt% HPMC. The relative density of the SiC tube sintered at 2200℃ and hold for 1h changes little with different content of HPMC obviously. The density of the sintered SiC tube in two-step sintering method increases from 3.00g/cm~3 to 3.07g/cm~3, and the average radial crushing strength and relative density reach 540MPa and 95.9%, respectively. The microstructure of the chemical etched surface indicate the abnormal growth of the SiC particles and the appearance of the plate-like grains.