摘要
目的提高Cr_2O_3-TiO_2基陶瓷涂层的辐射性能。方法以Cr_2O_3、TiO_2、NiO、Tb_4O_7为原料,经喷雾干燥及高温烧结致密化处理,制备成具有尖晶石和钙钛矿混合结构的Cr_2O_3-TiO_2基复合团聚型粉体,利用大气等离子喷涂法在TC4钛合金表面制备Tb_4O_7掺杂型Cr_2O_3-TiO_2基陶瓷涂层。采用扫描电子显微镜、X射线衍射仪、IRE-2红外辐射测试仪,分别对样品的显微组织结构、物相组成及辐射性能进行了表征。结果团聚造粒后,复合粉体的球形度和流动性较好,可满足等离子喷涂连续使用。所制备的Cr_2O_3-TiO_2基陶瓷涂层的熔化状态较好,扁平化程度较高,涂层中掺杂的Tb元素分布均匀。Tb^(4+)、Tb^(3+)等稀土元素离子,取代NiCr_2O_4尖晶石结构中半径相近的Ni^(2+)、Cr^(3+),导致单一晶体结构的整齐度被破坏,晶胞体积的变化引起晶体结构产生畸变,辐射条带显著加强和宽化。随着Tb_4O_7掺杂量的增多,涂层发射率逐渐上升,当掺杂量达到7.5%时,涂层在600℃的法向全发射率达到0.91。结论 Tb_4O_7稀土氧化物的加入可以有效提高Cr_2O_3-TiO_2基陶瓷涂层的发射率,稀土掺杂诱发尖晶石晶体结构畸变,从而改善涂层的辐射性能。
The work aims to improve the radiation property of Cr2O3-TiO2-based ceramic coating. Cr2O3, TiO2, NiO and Tb4O7 were used as raw materials to prepare Cr2O3-TiO2-based composite powders with mix structures of spinel and perovskite by spray drying and high temperature sintering densification treatment. Tb4O7 doped Cr2O3-TiO2-based high emissivity coatings were prepared on TC4 titanium alloy surface by atmospheric plasma spraying. The microstructure, phase composition and radiation property of samples were respectively characterized by SEM, XRD, and IRE-2 infrared radiometer. The sphericity and fluidity of the composite powders were preferable after agglomeration and suitable for continuous plasma spray. The prepared Cr2O3-TiO2-based ceramic coatings were in good melting state and high flatting degree and the distribution of Tb elements doped in the coatings was uniform. The doped rare earth elements like Tb^4＋ and Tb^3＋ ions replaced Ni^2＋ and Cr^3＋ with similar radius in the NiCr2O4 spinel. Thus, the uniformity of the single crystal structure was damaged, and the change of the cell volume inevitably caused the lattice distortion, then the radiation belt was strengthened and widened obviously. The emissivity of coat-ings went up as the content of Tb4O7 increased, and the normal total emissivity ran up to 0.91 at 600 ℃ when the dopant amount of Tb4O7 reached 7.5 wt.%. The addition of rare earth oxide like Tb4O7 can effectively improve the emissivity of Cr2O3-TiO2-based ceramic coating, and the doped rare earth can cause crystal structure distortion of spinel, so as to improve the radiation property of coating.
作者
杨震晓
倪立勇
杨杰
马康智
文波
曲栋
YANG Zhen-xiao, NI Li-yong, YANG Jie, MA Kang-zhi, WEN Bo, QU Dong(Aerospace Research Institute of Materials ＆ Processing Technology, Beijing 100076, Chin)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2018年第5期154-158,共5页
Surface Technology
