Anticorrosion treatment of galvanising vats - by thermal spraying of cobalt or ceramics

摘要

The inside walls of galvanizing vats suffer severe corrosion and the service life of a vat, even if produced from low-silicon special steel, varies from 2 to 5 years. The life can be extended many-fold by plasma spraying of cobalt, a high-cobalt alloy or ceramics. Rods or powder can be applied in a plasma flame or in a gas heated spray gun. A layer thickness of 1-2mm is normally adequate but can be increased in case of mechanical stress. Before the spraying, the surfaces are best shotblasted. A subsequent annealing improves the adhesion by sintering.