One of the latest innovations from Martin Thuo and his research group is finding a way to make micro-scale, liquid-metal particles that can be used for heat-free soldering plus the fabricating, repairing and processing of metals – all at room temperature. The project started as a search for a way to stop liquid metal from returning to a solid – even below the metal’s melting point. That’s something called undercooling and it has been widely studied for insights into metal structure and metal processing. But it had been a challenge to produce large and stable quantities of undercooled metals. Thuo’s research team thought if tiny droplets of liquid metal could be covered with a thin, uniform coating, they could form stable particles of undercooled liquid metal. The engineers experimented with a new technique that uses a high-speed rotary tool to sheer liquid metal into droplets within an acidic liquid. And then nature lends a hand: The particles are exposed to oxygen and then an oxidation layer is allowed to cover the particles, essentially creating a capsule containing the liquid metal. That layer is then polished until it is thin and smooth. http://www.news.iastate.edu/news/2016/04/25/liquidmetal Paper: http://www.nature.com/articles/srep21864
So, if you use a brush and paint it on a pipe joint, then slide on the other pipe, can you get it to become a solder by using ultrasound to release the liquid from its protective coating? the article is lean on how the coated droplet is applied. maybe just a slight tap of a hammer?