致密化工艺对氧化钛粉末及等离子喷涂涂层性能影响研究

采用喷雾干燥法制备了一种球形氧化钛团聚粉末， 并通过高温烧结及感应等离子球化工艺对团聚粉末进行 致密化处理。 利用扫描电子显微镜 (SEM)、 霍尔流速计和粉末颗粒强度仪对粉末性能进行了表征， 研究了不同致 密化处理工艺对粉末颗粒强度、 松装密度及流动性的影响。 采用大气等离子喷涂 (APS) 工艺制备了氧化钛涂层， 并对涂层的微观组织进行研究。 研究结果表明， 高温烧结工艺及等离子球化工艺均可有效提升氧化钛团聚粉末 的致密度， 经过高温烧结工艺后氧化钛粉末内部的细小颗粒呈现烧结熔融的趋势， 而采用等离子球化处理后的 团聚粉末直接形成了致密球体结构。 相比于高温烧结工艺， 等离子球化工艺对氧化钛粉末的致密化效应更为明 显， 粉末的颗粒强度可达 187.86 MPa， 松装密度可由 0.79 g/cm3 提升至 1.69 g/cm3， 流动性由 163.22 s/50g 加快 至 100.27 s/50g。 该粉末经过大气等离子喷涂沉积形成的氧化钛涂层孔隙率为 2.8 %， 与未经致密化工艺处理的氧 化钛团聚粉末相比， 制备的涂层致密化水平有了较大程度的提升， 涂层的平均显微硬度值由 434.18 HV0.3 提升至 744.37 HV0.3， 涂层的结合强度均值由 11.07 MPa 提升至 29.93 MPa。

Effect of Densifcation Process on Properties of Titanium Oxide Powder and Plasma Sprayed Coating

Spherical titanium oxide agglomerated powder was prepared by spray drying method, and the agglomerated powder was densified by high temperature sintering and induction plasma spheroidization. The powder properties were characterized by scanning electron microscopy (SEM), Hall flowmeter and powder particle strength tester, and the effects of different densification processes on the powder particle strength, bulk density and fluidity were studied. Titanium oxide coating was desopited by atmospheric plasma spraying (APS) process, and the microstructure of the coating was investigated. The results showed that both high temperature sintering process and plasma spheroidization process can effectively improve the density of agglomerated titanium oxide powder. After high temperature sintering process, the fine particles inside the titanium oxide powder showed the trend of sintering and melting, and the agglomerated powder after plasma spheroidization directly formeds a dense spherical structure. Compared with the high temperature sintering process, the densification effect of plasma spheroidization process on titanium oxide powder was more obvious. The particle strength of the powder can reach 187.86 MPa, the bulk density can be increased from 0.79 g/cm3 to 1.69 g/cm3, and the fluidity can be accelerated from 163.22 s/50g to 100.27 s/50g. The porosity of the titanium oxide coating deposited by atmospheric plasma spraying is 2.8 %, which was higher than that of the coating prepared by agglomerated titanium oxide powder without densification process (7.2 %).The HV0.3 average microhardness of the coating increased from 434.18 to 744.37, and the average bonding strength of the coating increased from 11.07 MPa to 29.93 MPa