微米尺度与纳米尺度陶瓷颗粒等离子喷涂(APS)、超音速火焰喷涂(HVOF)、冷喷涂制备MCrAlY-Al_2O_3复合涂层的微结构与性能对比

陶瓷颗粒增强型金属基复合涂层在诸多工业领域都有需求,其中包括炼钢工业。本文中,MCr Al Y-Al2O3复合粉末通过球磨法制备,并且通过等离子喷涂、超音速火焰喷涂和冷喷涂分别制备了MCr Al Y-Al2O3复合涂层。实验结果显示,可以选用不优先使基体与Al2O3结合的复合粉末控制涂层中的Al2O3含量。涂层粉末的微结构在冷喷涂涂层和超音速火焰喷涂涂层中得到了良好的保留,这是因为喷涂粒子未熔化或部分熔化。然而,对于等离子喷涂的涂层,大多数Al2O3颗粒被隔离在层状界面,在条状界面上形成连续的氧化皮。经退火处理后,由元素扩散引起的条状界面的强化使得超音速火焰喷涂和大气等离子喷涂的涂层硬度增大。此外,冷喷涂涂层由于退火后加工硬化效果的消除,硬度增加不像超音速火焰喷涂和等离子喷涂涂层那样明显。

Comparison of Microstructure and Properties of MCrAlY-Al2O3 Composite Coatings with Both Micro-sized and Nano-sized Ceramic Particles Deposited by Plasma Spraying,HVOF and Cold Spraying

Ceramic particle reinforced metal matrix composite coatings are required by many industrial fields including steelmaking industry. In this study, MCrAlY-Al2O3 composite powders were produced by ball milling, and the composite coatings were deposited by plasma spraying, HVOF and cold spraying. Results show that the Al2O3 fraction in coatings can be well controlled using composite powder due to no preferential impact debonding of matrix and Al2O3. The microstructure of spray powders is well retained into cold-sprayed coatings and HVOF sprayed coatings due to the nonmelted or partially molten condition of spray particles. However, for the plasma-sprayed coatings, most of Al2O3 particles are segregated at lamellar interface, forming a continuous oxide scale on splat interface. The cold-sprayed coatings present the highest hardness due to the additional work hardening effect. After the annealing treatment, the hardness of HVOF and APS coatings increases because of the strengthening of splat interface by the element diffusion. Moreover, the hardness increment for the cold-sprayed coatings is not as significant as the HVOF and plasma-sprayed coatings due to the elimination of strain hardening effect.