含碲钴基高温合金熔盐腐蚀行为探讨

Corrosion behavior of cobalt-based superalloys with tellurium in molten salt

摘要:

非真空环境下烧结不同Te含量的钴基合金粉末，研究其在静态800±5℃75%Na2SO4+25%NaCl下的高温熔盐腐蚀行为，采用OM、SED和 XRD衍射仪分析了合金金相组织、腐蚀产物形貌和物相组成。结果表明：随着钴基合金中含Te质量分数的增加，合金的高温熔盐腐蚀速率逐渐降低；当Te含量为1.6wt%左右时，合金基体表面形成均匀、致密的Cr2O3氧化保护膜及弥散在基体中的新相（CoTeO3、Fe2TeO5）抑制Co原子向晶界扩散，延缓合金基体元素溶解，平均腐蚀速率由不含Te的4.0483mg/(cm2*h)降低至0.216mg/(cm2*h) ，提高合金热腐蚀性能。

关键词:碲(Te);钴基合金;高温熔盐腐蚀

Abstract:

the corrosion behavior of cobalt-based alloy powder with different Te content that was sintered under non-vacuum environment is researched high temperature molten salt in a static 800±5℃75% Na2SO4+25% NaCl high temperature molten salt. Making use of OM, SEM and XRD diffraction analyze the alloy microstructure, corrosion product morphology and phase composition, and the results show that: with the increase of Te mass fraction in cobalt-based alloy, high-temperature molten salt corrosion rate decreased gradually; when the Te content is about 1.6wt%, the alloy substrate surface form a kind of homogeneous and dense Cr2O3 protection oxide film and the new phase (CoTeO3, Fe2TeO5) dispersed in the matrix to inhibit Co atoms diffusing to grain boundaries, which retard alloy matrix element dissolution and improve the performance of the alloy hot corrosion. Corrosion rate of cobalt-based alloy decreases from free Te 4.0483mg/(cm2*h) to 0.216mg/(cm2*h).

Key words:Tellurium (Te); cobalt-based alloy; high temperature molten salt corrosion