ZrO_(2)隔离层对铝酸镧基高发射率涂层物相组成和显微结构的影响

Effect of ZrO_(2) isolation layer on phase composition and microstructure of lanthanum aluminate high emissivity coating

为了探究ZrO_(2)隔离层对铝酸镧基高发射率涂层物相组成和显微结构的影响,以纯度(w)均为99%的La_(2)O_(3)、Al_(2)O_(3)、CaCO_(3)和Fe_(2)O_(3)为原料,按照La_(0.8)Ca_(0.2)Al_(0.8)Fe_(0.2)O_(3)的化学计量比,利用固相烧结法制备出Ca^(2+)、Fe^(3+)掺杂的铝酸镧(LaAlO_(3))粉体。将LaAlO_(3)粉体作为高发射率红外陶瓷粉体辐射剂,再以不同粒度的ZrO_(2)涂层为隔离层,制备出了LaAlO_(3)与ZrO_(2)复合的涂层(LCAFO/ZrO_(2)),并将其与单LCAFO(LaAlO_(3))涂层分别涂覆在工业窑炉炉衬用Al_(2)O_(3)空心球砖表面。采用XRD、SEM等方法对涂层进行分析。结果表明:LCAFO涂层与Al_(2)O_(3)空心球砖在1200℃时不反应,1400℃时反应生成LaAl_(11)O_(18),1600℃时,二者反应更加充分;反应层LaAl_(11)O_(18)的厚度随温度的升高逐渐增加。当ZrO_(2)隔离层涂覆于LCAFO层和Al_(2)O_(3)空心球砖之间时,复合涂层煅烧至1400℃时,无LaAl_(11)O_(18)相生成,无反应层出现。

In order to explore the effect of ZrO_(2)isolation layer on phase composition and microstructure of lanthanum aluminate high emissivity coating,Ca^(2+) and Fe^(3+) doped lanthanum aluminate(LaAlO_(3))powders were prepared using La_(2)O_(3),Al_(2)O_(3),CaCO_(3)and Fe_(2)O_(3)(all 99%purity)as raw materials via solid phase sintering method according to the stoichiometric ratio of La_(0.8)Ca_(0.2)Al_(0.8)Fe_(0.2)O_(3).The LaAlO_(3)and ZrO_(2)composite coating(LCAFO/ZrO_(2))were prepared using LaAlO_(3)powder as the high emissivity infrared ceramic powder radiation agent and ZrO_(2)coatings with different particle sizes as the isolation layer.The developed coating and the LCAFO(LaAlO_(3))coating were spread on the surface of bubble Al_(2)O_(3) bricks for the lining of industrial furnaces,respectively.The coatings were analyzed using XRD and SEM.The results show that LCAFO coating does not react with bubble Al_(2)O_(3) bricks at 1200℃,but they react at 1400℃forming LaAl_(11)O_(18),and the reaction is more sufficient at 1600℃.The thickness of the LaAl_(11)O_(18)layer increases with the temperature rising.When the ZrO_(2) isolation layer is coated between the LCAFO layer and the bubble Al_(2)O_(3) bricks,no LaAl_(11)O_(18) phase exists and no reaction layer appears at 1400℃.