Luzin V, Spiridonov P, Spencer K, Gnaupel-Herold T
Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2232, Australia.
School of Engineering, The University of Newcastle, Callaghan, NSW 2308, Australia.
J Therm Spray Technol. 2020;29(6). doi: 10.1007/s11666-020-01077-8.
Protective coatings based on an Al-AlO metal matrix composite (MMC) were sprayed using dynamic metallization (DM), a low-pressure cold spray variant. A series of samples approximately 1 mm in thickness were sprayed using different spray process parameters (temperature, velocity) and different feedstock powder compositions (Al, Zn, AlO). This resulted in MMCs of different phase compositions and slightly different physical conditions of coating formation. The through-thickness residual stresses that accumulate in coatings during the spray process were studied using neutron diffraction in all phases comprising the MMCs. The overall residual stress in the coating (macrostress) was compressive, which is in good agreement with the data on residual stress observed in other cold spray coatings, accumulating as a result of the peening process. However, due to the slightly elevated spray temperature characteristic of DM in comparison with other cold spray variants, thermal stresses are also present and play an equally important role in the accumulation of residual stress in each phase. Because of the multi-phase composition and thermal mismatch between the metal and ceramic components of the MMC, inter-phase microstresses also accumulate. A micro-mechanical explanation of the observed tensile microstress in Al/Zn versus compressive stress in AlO is proposed.
基于铝-氧化铝金属基复合材料（MMC）的防护涂层采用动态金属化（DM）喷涂，这是一种低压冷喷涂变体。使用不同的喷涂工艺参数（温度、速度）和不同的原料粉末成分（铝、锌、氧化铝）喷涂了一系列厚度约为1毫米的样品。这导致了不同相组成的MMC以及涂层形成时略有不同的物理条件。在喷涂过程中，使用中子衍射研究了MMC所有相中涂层内累积的贯穿厚度残余应力。涂层中的总残余应力（宏观应力）是压缩性的，这与在其他冷喷涂涂层中观察到的残余应力数据一致，残余应力是由于喷丸过程而累积的。然而，由于与其他冷喷涂变体相比，DM的喷涂温度略有升高，热应力也存在，并且在每个相的残余应力累积中起着同样重要的作用。由于MMC的多相组成以及金属和陶瓷成分之间的热失配，相间微应力也会累积。针对在铝/锌中观察到的拉伸微应力与在氧化铝中观察到的压缩应力，提出了一种微观力学解释。
