METHOD OF APPLYING PROTECTIVE COATINGS ONTO CARBON-MATERIAL OBJECTS Russian patent published in 1997 - IPC

FIELD: protective coatings. SUBSTANCE: invention relates to a process of manufacturing objects from carbon materials, in particular, to the process of applying protective coating onto carbon material by microarc anodizing and may find use in metallurgy, instrumentation engineering, etc. Method includes formation of a coating with total thickness 400-600 mcm via successively applying aluminium layers and their microarc anodizing in silicate solution containing 20-30 g/l of liquid glass and 2-3 g/l of sodium hydroxide, thickness of the first aluminium layer constituting 40-50% of total coating thickness and subsequent layers 50-100% of the first layer thickness. Anodizing is carried out first in potentiostatic mode under voltage 450-500 V and constant electric power, which is maintained by controlling velocity of increase in anodized surface and, when entire surface is anodized, by carrying out the process in a self-controlled mode with the power dropping until final current density 1-3 Ohm/sq.dm and voltage 500-550 V are achieved. A part of surface of anodizing layers, before aluminium layer is applied, is mechanically removed. In this case, 5-50% of anodized surface is preferably removed by handling with a wire brush either immediately or not later than on the 3-5th day after anodizing. When coating is formed, its surface is covered with graphite by means of rubbing. Method essentially increases electroconductance of coatings with no loss in their protective quality which provides effective working capacity of coatings under great current loadings. Simultaneously power consumption and operational cost of coating application are both reduced, and performance characteristics of coatings on graphitized electrodes are increased. EFFECT: improved operational characteristics of coatings. 6 cl, 2 dwg, 1 tbl