摘要
利用热压烧结法,在2400℃烧结温度下,制备了NbMo固溶体(此后记作(Nb,Mo)ss)基陶瓷颗粒增强复合材料。其中,ZrB2陶瓷增强相的体积分数分别为15%,30%,45%和60%。研究了在800,1000和1200℃下,ZrB2含量对复合材料抗氧化性和氧化产物演变的作用。结果表明,氧化温度和ZrB2含量均对复合材料的氧化行为有影响。从氧化速率常数角度讲,ZrB2-(Nb,Mo)ss复合材料的抗氧化性随ZrB2含量的增加而提高,随氧化温度的提高而降低。8001000℃的氧化产物中含有膜状Nb2Zr6O17相,能作为屏障阻止氧气向基体扩散,因此在8001000℃时,复合材料氧化速率较低。然而,在1200℃氧化时未发现Nb2Zr6O17相,MoO3的剧烈挥发和ZrO2的体积效应破坏了Nb2Zr6O17保护层,导致了氧化层严重剥落,材料的抗氧化性极差。综上,结合观察到的氧化产物形貌,详细阐述了不同ZrB2含量的复合材料在不同温度下的抗氧化机制。
The NbMo solid solution(denoted as(Nb,Mo)ss hereinafter) matrix ceramic composites reinforced with 15 vol%,30 vol%,45 vol%,and 60 vol% ZrB2 particles were fabricated by hot-pressing sintering at 2400℃.The effect of the ZrB2 content on the isothermal oxidation resistance and the oxide scales microstructure evolution at 800,1000,and 1200℃was investigated.The results show that both temperature and ZrB2 content have an influence on the oxidation behavior.The oxidation resistance of ZrB2-(Nb,Mo)ss composites increases with increasing ZrB2 content and decreases with increasing oxidation temperature from the view point of parabolic rate constant.The oxide scales at 8001000℃ contain special film-like Nb2 Zr6 O17,acting as a barrier against oxygen diffusing inwards and leading to low parabolic rate constant.However,no Nb2 Zr6 O17 layer is observed at 1200℃because the volatile MoO3 and the volume effect of ZrO2 damage the Nb2 Zr6 O17 protective layer which results in severe spallation and poor oxidation resistance.Possible oxidation mechanisms at different temperatures with varying ZrB2 contents were discussed according to the observed oxide morphologies and the results above.
作者
高远
刘宗德
王琦
孙有美
龚燕
Gao Yuan;Liu Zongde;Wang Qi;Sun Youmei;Gong Yan(Key Laboratory of Condition Monitoring and Control for Power Plant Equipment of Ministry of Education,North China Electric Power University,Beijing 102206,China)
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2019年第12期3846-3854,共9页
Rare Metal Materials and Engineering
基金
National Natural Science Foundation of China(11372110)
