纳米陶瓷粉体对HT250微观组织和热疲劳的影响

研究了在HT250中加入0.1%纳米陶瓷粉体对其显微组织和热疲劳的影响,结果表明:(1)纳米陶瓷粉体作为液态HT250的外来异质形核的核心,起到孕育作用,促进石墨化,使石墨变得细小且分布均匀,长度减小,对基体的割裂作用减弱;珠光体体积分数增加且得到细化,片间距减小,基体连续性得到改善;(2)添加0.1%纳米陶瓷粉体后,HT250的导热系数下降,平均下降4.6%;(3)与未添加纳米陶瓷粉体的HT250相比,添加0.1%纳米陶瓷粉体后,热膨胀系数下降,平均下降8.6%;(4)添加0.1%纳米陶瓷粉体后,HT250的热疲劳性能提高17%。

Influence of Nano-Ceramic Powder on Microstructure and Thermal Fatigue Property of HT250

The influences of adding 0.1% nano-ceramic powder into HT250 on its microstructure and thermal fatigue property were investigated. The results showed： （1）as the extraneous heterogeneous nuclei of the liquid gray iron,the nano-ceramic powder had inoculation effect that promoted graphitization and thereby made the graphite more finer and distributing more uniformly,the graphite length reduced,therefore,the matrix-dissevering effect of the graphite was weakened;the pearlite content increased,the pearlite inter-layers distance was reduced,therefore the matrix continuity was improved; （2）after adding 0.1% nano-ceramic powder,the thermal conductivity coefficient of the gray iron decreased by 4.6% averagely; （3）compared with the gray iron without nano-ceramic powder addition,the thermal expansion coefficient of the gray iron with 0.1% nano-ceramic powder addition decreased by 8.6% averagely; （4）after adding 03% nano-ceramic powder,the thermal fatigue property of the gray iron increased by 17%.