Abstract: The method and apparatus treat a surface of natural rock or artificial stone-like material to give to this surface an attractive finish. A high temperature jet of plasma and a high speed jet of cooling fluid are projected onto the surface to be treated. The two jets are moved on the surface at a given speed with the jet of cooling fluid following the plasma jet. The speed of movement is selected so that the high temperature plasma jet heats only a thin superficial layer of rock or stone-like material. As the jet of cooling fluid follows the jet of plasma, it suddenly cools the thin superficial layer just heated by the plasma jet to cause a thermal shock which bursts particles of rock or stone-like material at the surface thereof, and blows these particles off the rock surface.

Abstract: Copper based substrates for use at high temperatures in oxidizing atmospheres are made up of a copper core overlaid with a protective nickel oxide barrier layer formed in situ and an external protective layer of nickel. The process for forming the protective nickel oxide barrier layer comprises the steps of subjecting the copper core to oxidation to form a cuprous oxide surface layer over the copper core, reducing the surface of the cuprous oxide layer to regenerate copper to regain conductivity, plating a surface layer of nickel over the copper layer, and annealing the coated copper core to scavenge at least some of the oxygen from the cuprous oxide layer and react it at the interface with the plated nickel layer to form the protective nickel oxide barrier layer.