纳米Al2O3–ZrO2涂层的制备与微观结构

Preparation and Microstructure of Nanostructured Al_2O_3–ZrO_2 Coating

用Al(NO3)3.9H2O、ZrOCl2.8H2O及NH4OH作为原料,采用溶胶–凝胶工艺制备出Al2O3–40%(质量分数)ZrO2纳米复合粉体。并以此粉体为原料,用等离子喷涂工艺在不锈钢基体上制备了Al2O3–40%ZrO2纳米涂层。采用X射线衍射、扫描电子显微镜及高分辨透射电子显微镜分析粉体及涂层的物相及微观结构。结果表明:当煅烧温度从900℃升高至1 200℃过程中,复合粉体中的θ-Al2O3逐渐向α-Al2O3转变,当煅烧温度达到1 200℃时,粉体中仅存在α-Al2O3。此外,单斜相二氧化锆(m-ZrO2)与四方相二氧化锆(t-ZrO2)共存于粉体中,并且m-ZrO2含量随煅烧温度及保温时间的增加而增加。喷涂后的Al2O3–40%ZrO2纳米涂层是由尺寸约为50 nm的晶粒及一些非晶相组成,晶粒的物相为α-Al2O3、γ-Al2O3及t-ZrO2。

Al2O3–40% in mass ZrO2 nano composite powder was prepared by sol–gel method with Al（NO3）3·9H2O,ZrOCl2·8H2O and NH4OH solution as starting materials,and then near-eutectic Al2O3–40%ZrO2 coating on stainless steel substrate was deposited by atmospheric plasma spray using the nano composite powder as feedstock.The phase composition and microstructure of the composite powder and as-sprayed coating were investigated by X-ray diffraction,scanning electron microscope and high resolution transmission electron microscope.The results show that θ-Al2O3 transformed to α-Al2O3 gradually in the composite powder with the calcining temperature increasing from 900 ℃ to 1 200 ℃,and only α-Al2O3 existed when the temperature reached 1 200 ℃,while m-ZrO2 and t-ZrO2 coexisted in the composite powder.Meanwhile,the content of m-ZrO2 increased with the rise of calcining temperature and holding time.In addition,the as-sprayed Al2O3–40%ZrO2 coating was composed of grains with the size of about 50 nm and some amor-phous phase.The phase composition of as-sprayed the Al2O3–40%ZrO2 coating was identified as α-Al2O3,γ-Al2O3 and metastable t-ZrO2.