THERMOSPRAY METHOD FOR PRODUCTION OF ALUMINIUM POROUS BOILING SURFACES

摘要

A method for producing a porous boiling surface with exceptional adhesion qualities and mechanical strength while at the same time maintaining the high degree of open cell porosity required for effective boiling heat transfer wherein a bond coating of pure aluminum is produced using a thermospray gun to melt an aluminum wire and impinge the molten aluminum particles against the metallic substrate in an inert gas stream projected from the gun nozzle located between 2 and 4 inches from the substrate. The bond coating has a porosity of less than 15 percent and a thickness not greater than 4 mils. The nozzle to substrate distance is then increased to 4 to 10 inches and a top coating of pure aluminum is formed having a porosity greater than 18 percent and a thickness of at least four times the thickness of the bond coating.