【作者】 周立忠；

【导师】 阎殿然；

【作者基本信息】 河北工业大学 ， 材料学， 2004， 硕士

【摘要】 本工作利用Al（OH）₃溶胶和聚乙烯醇做粘合剂，采用包覆方法和喷雾造粒制粉方法，成功制备出适宜喷涂纳米—微米、纳米—纳米SiC／Al₂O₃复合粉末。研究发现，n-SiC粒子含量及复合粉末烧结温度是影响SiC／Al₂O₃复合粉末及涂层微观结构均匀性的重要参数。通过对比试验，优化出纳米—微米n-SiC／Al₂O₃复合粉末最佳制备工艺，并采用等离子喷涂技术成功制备出SiC／Al₂O₃纳米复相陶瓷涂层。通过实验得到以下结论： 1、以Al（OH）₃溶胶为粘合剂制备纳米—微米n-SiC／Al₂O₃包覆复合粉末工艺为： Al（OH）₃溶胶制备→加入μm-Al₂O₃→搅拌→加入n-SiC粒子→搅拌→过滤→干燥→800℃烧结→研磨→过筛。 2、实验结果表明，利用Al（OH）₃溶胶粘合剂法制备的纳米—微米n-SiC／Al₂O₃复合粉末，采用P＞40kW的功率喷涂，SiC会发生分解。喷涂功率＜40kW，会得到n-SiC分布于μm-Al₂O₃晶内和晶界的纳米—微米n-SiC／Al₂O₃复相涂层。 3、纳米—微米n-SiC／Al₂O₃复相陶瓷涂层中，n-SiC粒子有一最佳含量。当n-SiC粒子含量为3Vol％时，复合涂层结构致密，气孔率低，涂层硬度有较大提高，并且摩擦磨损性能优于其它n-SiC粒子含量复相涂层。 4、提出了利用纳米一微米n-SiC／Al₂O₃包覆复合粉末所制的陶瓷涂层中n-SiC粒子分布于μm-Al₂O₃晶内的机理：在喷涂过程中微米级Al₂O₃完全熔化形成液滴，n-SiC粒子存于液滴表面，在液滴撞击基材平铺过程中n-SiC粒子进入液滴内部形成。 5、采用喷雾造粒方法制备纳米—纳米SiC／Al₂O₃复合粉末最佳工艺参数为：固体物含量为25wt％；粘合剂比例为2.3wt％；干燥温度510～530℃；烧结温度1200℃；压缩空气压力为0.3±0.05MPa。 6、纳米—纳米SiC／Al₂O₃复相陶瓷涂层形成过程为：干粉颗粒内外层在喷涂过程中受热历史不同，导致内层纳米粒子仅仅熔化而没有结晶长大，涂层中形成了许多呈烧结形态纳米粒子构成的团聚体。更多还原

【Abstract】 In this paper, A1(OH)3 sol and Polyvinvl Alcohol were used as binder, nano-micrometer, nano-nano SiC/Al2O3 composite powder was prepared through wrapping and spraying granulation method. The content of n-SiC and the sinter temperature of composite powder greatly influence the coatings’ microstructrural uniform. The preparation route of nano-micrometer n-SiC/Al2O3 composite powder were optimized by comparative investigation, and the nanocomposite SiC/Al2O3 ceramic coating was plasma sprayed. By experiments, conclusions were drawn as following:1 The technology of nano-micrometer n-SiC/Al2O3 wrapping composite powder was determined, prepared using A1(OH)3 sol as binder:Preparation of Al(OH)3 sol→Padded m-Al2O3→stirred→added n-SiC particle →filtered→dried→sintered at 800℃→ground→sifted2 The results indicate that, for the nano-micrometer n-SiC/Al2O3 composite powder, using A1(OH)3 sol as binder, SiC would decompose when spraying power is higher than 40kW; the nano-micrometer n-SiC/Al2O3 composite coating could be obtained when the power below 40kW, and n-SiC particles were located within m-Al2O3 grains and grain boundary.3, When 3Vol% n-SiC particle were added, the composite coating is quite dense ,with low porosity, and the hardness was greatly increased ,exhibiting relatively higher wear resistance than other composite coating with other n-SiC particle contents.4, The formation mechanism of the n-SiC particles in the ceramic coating prepared by the nano-micrometer n-SiC/Al2O3 composite powder located within m-Al2O3 grains is revealed:m-Al2O3 would be well melted during spraying and form droplet, the n-SiC particles existing on the surface of droplet, then the particle enter the droplet when it is impacted and flattened on the substrate.5 The best technical parameters of nano-nano SiC/Al2O3 composite powder prepared through spray granulation method: solids content 25wt%;binder content 2.3wt%;dryingtemperature 510~530℃ ;sinter temperature 1200℃ ; contract air pressure 0.3 + 0.05MPa.6 , The formation of nano-nano SiC/Al2O3 composite ceramic coating: The heating difference of the powder in-outer layer during spraying results in that the inner nanoparticles are only partially melted, without growing into larger grain, a lot of nanoparticle agglomerates with sintered shape were detected in the coating.更多还原