反应等离子喷涂AlNbO4-Al2O3-NbOx复合涂层的研究

目的研究等离子喷涂Al-Nb_2O_5铝热体系制备的AlNbO_4-Al_2O_3-NbO_x复合涂层的组织、力学性能和摩擦磨损性能。方法以Nb_2O_5粉和Al粉为原料,通过喷雾造粒制备复合粉,采用等离子喷涂技术喷涂Al-Nb_2O_5复合粉体,利用复合粉的自反应制备出含有AlNbO_4、Al_2O_3和NbO_x的复合陶瓷涂层。利用扫描电镜、EDS和XRD检测和分析复合涂层的组织和物相。用显微硬度计测定复合涂层的硬度,并用硬度压痕法测量裂纹扩展能(Gc)。用销盘式磨损试验机测定涂层在无润滑条件下的摩擦磨损性能。结果 XRD分析可知,复合涂层由AlNbO_4、Al_2O_3和NbO_x相组成,SEM显示涂层为交替分布的层片状组织。在28~32 k W功率范围内,随着喷涂功率的升高,涂层的硬度增加,喷涂功率为32 k W时,涂层硬度最高,为912HV0.1。随着喷涂功率的升高,涂层的裂纹扩展能先升高后降低,喷涂功率为30 k W时,涂层的裂纹扩展能最大,为14.14J/m2。摩擦系数随功率的升高先降低后保持不变,28 k W时,涂层的摩擦系数为0.7~0.8,30 k W和32 k W时,涂层的摩擦系数为0.5~0.6。磨损量随喷涂功率的增加先降低后升高,喷涂功率为30 k W时,涂层的磨损量最小。磨损后的试样进行SEM检测发现有明显的犁沟、凹槽和剥落。结论涂层具有由AlNbO_4、Al_2O_3和NbO_x相组成的交替分布的多相层片状组织。喷涂功率为30 k W时,复合涂层的性能最好。复合涂层的主要磨损机制为磨粒磨损和疲劳磨损。

AlNbO4-Al2O3-NbOx Composite Coating Prepared by Reactive Plasma Spraying

The work aims to study microstructure, mechanical properties as well as friction and wear properties of AlNbO4-Al2O3-NbOx composite coating prepared by plasma spraying in Al-Nb2O5 thermit system. A composite ceramic coating containing AlNbO4, Al2O3 and NbOx was fabricated by plasma spraying self-made Al-Nb2O5 composite powder prepared by spray granulation with Nb2O5 and Al powders. Structure and phase composition of the composite coating were tested and analyzed with a scanning electron microscope (SEM), energy dispersive analyzing system (EDS) and X-ray diffractometer (XRD), microhardness with a microhardness tester and crack extension force (Gc) in hardness indentation method. The friction and wear properties of the unlubricated coatings were tested with pin-disc-type abrasion tester. The XRD analysis showed that the composite coating consisted of AlNbO4, Al2O3 and NbOx phases. The SEM results showed that the coating had an alternatively distributed lamellar structure. In the range of 28~32 kW, hardness of the coating increased with the increase of spraying power and was up to 912HV0.1 at 32 kW; crack extension force of the coating increased firstly then decreased and the maximum was 14.14 J/m2 at 30 kW; the friction coefficient decreased firstly and then remained constant with the increase of power; the friction coefficient was 0.7~0.8 at 28 kW, and 0.5~0.6 at 30 kW and 32 kW; the wear volume decreased firstly and then increased, and amounted to the minimum at 30 kW. Obvious furrow, groove and peeling-off were observed on the worn sample. The composite coatings have an alternatively distributed multiphase lamellar structure consisting of AlNbO4, Al2O3 and NbOx. Performance of the composite coating is the best at the spraying power of 30 kW. Main wear mechanisms of the composite coating are abrasive wear and fatigue wear.