GB1070396A - Method of depositing metal coatings in holes, tubes, cracks, fissures and the like - Google Patents

Abstract

In a gas plating process of depositing metal on substrates containing holes, crevices, small voids, cavities, or dead end fissures or bores extending therethrough, the substrate is heated to the decomposition temperature of the thermally decomposable plating gas which is subjected to pulsating pressure conditions in which the pressure is alternately and repetitively reduced and increased, the gaseous decomposition products formed being removed during the pressure reduction. The pulsating pressure conditions are effected either by alternately and repetitively creating a vacuum, or by shutting off and on the flow of gas, or by creating sonic waves in the gas, or by the use of moving walls or diaphragms. In the examples the plating gas is nickel carbonyl, iron carbonyl or aluminium triisobutyl which may be mixed with hydrogen, carbon monoxide, carbon dioxide, nitrogen, methane, helium, argon. The substrates coated may be plaster, carbon coated plaster, brass, copper tubes or balls and ceramic. According to Figure 1 (not shown) the bore (11) of a metal tube is supplied with nickel carbonyl via a conduit (17) hermetically sealed to the bore inlet, the pulsating gas pressure being effected by a solenoid valve (20) or a rotary valve (29). Waste gases are passed to a condenser via outlet (23). In a modification Figure 4 (not shown) the plating chamber (50) is connected with an inlet solenoid valve (56) and an outlet solenoid valve (60) connected to a timing switch (62). According to Figure 5 (not shown) an electrically operated sonic vibrator (80) in dome shaped plating chamber (75) produces the pulsating gas pressure.