How to Get Sprayed Metal Coatings to Stick

Melting Can Hinder Impact-Induced Adhesion

Micrographs of a metal surface after impact by metal particles. Craters are formed due to melting of the surface from the impact.

February 12, 2018 | Source: Massachusetts Institute of Technology, news.mit.edu, 22 Nov 2017, David L. Chandler

When spraying metal coatings, melting hurts rather than helps, MIT research reveals.

When bonding two pieces of metal, either the metals must melt a bit where they meet or some molten metal must be introduced between the pieces. A solid bond then forms when the metal solidifies again. But researchers at MIT have found that in some situations, melting can actually inhibit metal bonding rather than promote it.

The surprising and counterintuitive finding could have serious implications for the design of certain coating processes or for 3-D printing, which both require getting materials to stick together and stay that way.

The research, carried out by postdocs Mostafa Hassani-Gangaraj and David Veysset and professors Keith Nelson and Christopher Schuh, was reported in two papers, in the journals Physical Review Letters and Scripta Materialia.