Abstract: A thermal energy storage system for absorption of heat from a heat source having a temperature above a predetermined temperature and release of heat to a heat sink having a temperature below the predetermined temperature. The system comprises a heat storage mass comprising a condensed state material which changes between the solid and liquid phases at about the predetermined temperature and a compartment for containing the heat storage mass. The compartment includes means providing an area for transfer of heat between a fluid and the material. The material may be an aliphatic diamine corresponding to the general formulaH.sub.2 N--(CH.sub.2).sub.n --NH.sub.2where n is an integer between 4 and 14 inclusive, bis(hexamethylene)triamine, 3-aminobutylcyclohexylamine or p-phenylenediamine. Mixtures of these amines with each other may be used, particularly including certain eutectic mixtures having melting points near room temperature.

Abstract: A plasma arc spray overlay of cladding metals is used over joints between clad metal pieces to provide a continuous cladding metal surface. The technique permits applying an overlay of a high melting point cladding metal to a cladding metal surface without excessive heating of the backing metal.