Thermal properties of La2O3-YSZ powder fabricated by heterogeneous precipitation
Thermal properties of La2O3-YSZ powder fabricated by heterogeneous precipitation
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DOI：
10.1016/j.jallcom.2009.07.005
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发表时间：
2009-11
影响因子：
6.2
通讯作者：
S. J. Hong;Sohyeon Kim;Won-Kyu Han;S. G. Kang
中科院分区：
文献类型：
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作者：
S. J. Hong;Sohyeon Kim;Won-Kyu Han;S. G. Kang
研究了氧化钇稳定氧化锆（YSZ）热障涂层（TBC）材料上La 2 O3的非均相沉淀（HP）均匀包覆，以降低致密化程度，提高工作温度下的热稳定性。以YSZ为基料，La（NO3）3·6 H2O为La源，NH 4 HCO 3为沉淀剂，采用HP法在YSZ粉体表面包覆La 2 O3。在200°C时，La的相转变为La 2（CO 3）3·8H 2 O + La 2 O3 CO 3;在500 ° C时，La的相转变为La 2 O3 CO 3 + La 2 O3。La_2（CO_3）_3·8H_2O经800°C空气热处理2 h后得到La_2O_3。为了比较La_2O_3与YSZ（LYSZ）粉末在高压下混合后的性能，采用球磨法制备了LYSZ粉末。结果表明，La_2O_3在HP-LYSZ粉体中的分布比在BM-LYSZ粉体中更均匀。La 2 O3的这种不同分布影响了两种LYSZ粉末在高温下的热性能。在1300°C下烧结12 h后，HP-LYSZ粉末的相对密度比BM-LYSZ粉末低约5%，这是由于直径小于1μm的孔隙分布不同所致。此外，HP-LYSZ在退火过程中具有比BM-LYSZ更好的热稳定性，因为在1400°C下长时间退火后BM-LYSZ具有更大的单斜相比例。因此，HP-LYSZ粉末可能是用于TBC应用的有用材料。
This study focused on whether La2O3was uniformly coated by heterogeneous precipitation (HP) on the thermal barrier coating (TBC) material, yttria stabilized zirconia (YSZ), in order to decrease densification and enhance thermal stability at operating temperature. La2O3was coated on YSZ powder by HP using YSZ as a base material, La(NO3)3·6H2O as an La source, and NH4HCO3as a precipitant. The phase of the as-precipitated La on YSZ was La2(CO3)3·8H2O, which was changed to La2(CO3)3·8H2O+La2O3CO3at 200°C and La2O3CO3+La2O3at 500°C in air after 2h. La2O3was finally obtained by heat treatment of as-precipitated La2(CO3)3·8H2O at 800°C in air for 2h. In order to compare several properties of La2O3mixed with YSZ (LYSZ) powder by HP, LYSZ powder was prepared by ball-milling (BM). It was found that La2O3was more uniformly distributed in the as-prepared HP-LYSZ powder than in the BM-LYSZ powder. This different distribution of La2O3affected the thermal properties of the two LYSZ powders at high temperature. After sintering at 1300°C for 12h, the HP-LYSZ powder showed an approximately 5% lower relative density than the BM-LYSZ powder, caused by the different distribution of pores with diameters below 1μm. In addition, the HP-LYSZ had better thermal stability than the BM-LYSZ during annealing, because BM-LYSZ had a greater ratio of the monoclinic phase after lengthy annealing at 1400°C. Therefore, HP-LYSZ powder could be a useful material for TBC applications.