摘要
本文通过改变电解液中Na_(2)SiO_(3)浓度研究不同孔隙率的微弧氧化膜层增强铌合金耐烧蚀性能,借助X射线计算机断层扫描技术还原膜层的内部孔隙结构,并结合有限元模拟建立模型还原膜层热烧蚀过程。结果表明:随着Na_(2)SiO_(3)浓度的增加,膜层的孔隙率呈现出先降低后增加的趋势;当Na_(2)SiO_(3)为10 g/L时,膜层孔隙率最小为15.08%,其中40.2%孔隙的孔径比为0.6~0.7,呈现出连通孔向孤立孔转变的状态。此时,膜层抗烧蚀性能最好,经1000℃烧蚀15 min后,膜层质量损失仅为0.017 mg/dm^(2)。孤立孔虽然可以降低膜层密度,但由于其在空间上的分离性,有助于分散热应力,减小局部应力集中,从而提高膜层的抗烧蚀性能。相比之下,连通孔的大规模出现增加了膜层的热导率,导致膜层更容易发生热应力集中,从而出现裂纹造成膜层脱落,形成更大规模的烧蚀。
Aiming to enhance the ablation resistance of niobium alloys,this study focused on the preparation of plasma electrolytic oxidation(PEO)coatings with varying porosity by modulating the concentration of Na_(2)SiO_(3) in the electrolyte.The internal pore structure of the coating was reconstructed through X-ray computed tomography scanning,while the thermal ablation process was simulated using finite element analysis,facilitating the establishment of a comprehensive model for the thermal behavior of the coating.The results show that,as the concentration of Na_(2)SiO_(3) increases,the porosity of the coating exhibits a trend of an initial decrease followed by an increase.Notably,at Na_(2)SiO_(3) concentration of 10 g/L,the coating achieves its minimum porosity of 15.08%,with 40.2%of the pores exhibiting a pore-size ratio within the range of 0.6 to 0.7,thereby demonstrating the transition from interconnected voids to isolated pores.This phenomenon can be attributed to the presence of isolated pores,which decrease the coating’s density.Bowever,their spatial separation facilitates the dispersion of thermal stresses,thereby mitigating local stress concentrations and enhancing the coating’s ablation resistance.Conversely,the extensive presence of interconnected pores elevates the thermal conductivity of the coating,rendering it more susceptible to the formation of thermal stress concentration cracks,which consequently leads to more pronounced ablation of the coating.
作者
宁炳坤
谢天祥
钱伟峰
陈永楠
王楠
李延超
张文
NING Bingkun;XIE Tianxiang;QIAN Weifeng;CHEN Yongnan;WANG Nan;LI Yanchao;ZHANG Wen(School of Materials Science and Engineering,Chang’an University,Xi’an 710064,China;Institute for Refractory Metal Materials,Northwest Institute for Nonferrous Metal Research,Xi’an 710016,China)
出处
《中国有色金属学报》
2025年第9期3102-3114,共13页
The Chinese Journal of Nonferrous Metals
基金
国家自然科学基金资助项目(52271051)
陕西省技术创新引导专项“三项改革”项目(2024ZC-YYDP-109)
陕西省秦创原“科学家+工程师”队伍建设项目(2023KXJ-272)。
作者简介
通信作者:陈永楠,教授,博士,电话:029-82337343,E-mail:frank_cyn@163.com。
