PROCESS FOR THE TREATMENT OF AMORPHOUS CARBON OR GRAPHITE MANUFACTURED ARTICLES, FOR THE PURPOSE OF IMPROVING THEIR RESISTANCE TO OXIDATION, SOLUTIONS SUITABLE FOR ATTAINING SUCH PURPOSE AND RESULTING PRODUCT

摘要

1315012 Impregnated carbon CENTRO SPERIMENTALE METALLURGICO SpA 8 Sept 1970 [22 Jan 1970] 43023/70 Heading C1A [Also in Division D1] The resistance to oxidation of an amorphous carbon or graphite article is increased by degassing the article under vacuum, contacting it under vacuum with a solution comprising, by weight (a) 26À0-10À0% phosphoric acid; (b) 0À1 to 6À0% of at least one compound selected from Group IIa and IIb (calcium, cadmium or zinc) salts, oxides and hydroxides; (c) 16À9 to 2À0% of at least one of sodium tetraborate decahydrate and boric acid; and (d) 57 to 76% water, causing impregnation of the article by the solution, removing the article from the solution and drying the article. The solution may further comprise up to 6% of at least one compound selected from nitric acid, sodium nitrite and sodium carbonate. The impregnation can be performed at elevated temperature and pressure, and by varnishing or immersion. The article may be an electrode, crucible, refractory brick, or resistor.