While revisiting the Cold Spray publications based on our Aluminum powders, we came across two works by the Massachusetts Institute of Technology that are worth slowing down for.
- Particle size effects in metallic microparticle impact-bonding, Ian Dowding, Ph.D., Mostafa Hassani et al. (2019);
- Surface oxide and hydroxide effects on Aluminum microparticle impact bonding, Jasper Lienhard, Cameron Crook et al. (2020).
Full quotes on our Literature webpage: https://lnkd.in/gTRx9aYu
At time of publication co-authors were affiliated with UC Irvine, North Carolina State University, U.S. Army DEVCOM Army Research Laboratory.
First paper: rather than process optimization, the problem is stripped down to: why does bonding happen at all?
Larger Aluminum particles actually generate hotter interfacial jets on impact, which locally reduce the material’s strength and can lower the critical bonding velocity. That helps explain trends that are reported in Literature.
The second paper deals with Aluminum oxides. The takeaway: most common thermal treatments or moderate humidity exposure have no significant impact. At contrary, sustained high humidity does, and when that happens, the critical velocity tangibly increases.
Taken together, these papers could be considered less like incremental cold spray studies and more like groundwork. Powder production, packaging, storage, and handling are implied as first-order variables.
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