THE EFFECT OF LIQUID GALLIUM ON THE STRENGTHS OF STAINLESS-STEEL AND THERMOPLASTICS

We have investigated the effect of liquid gallium on type 316L stainle ss steel (as a candidate for the P-V-T pressure vessel), and four ther moplastics: two semicrystalline (high-density polyethylene and polypro pylene) and two amorphous (polystyrene and poly( methyl methacrylate)) . Specimens were coated with gallium and held at elevated temperatures and reduced pressure for extended periods. Measurements conducted on the plastics include weight change analyses, tensile tests and particl e diffusion analysis using dispersion X-ray spectroscopy. For the stai nless steel specimens, tensile and corrosion tests were conducted. Sca nning electron microscopy was used to determine the level of corrosion . The results are compared with specimens heat treated identically but without gallium contact. After 3 months, the gallium corroded the sur face of the steel to a depth of only 12 mu m. No penetration path of t he gallium into the steel has been observed. The gallium was also foun d to cause no change in the mechanical properties of the polymers test ed, nor was it found to have caused any weight change in the specimens .