| 摘要 |
The invention pertains to metallurgy and concerns protective coatings and electrolytic procedures for applying them. More specifically it concerns a method of producing durable coatings on ferrous and non-ferrous metal surfaces by the method of micro-arc oxidation and can be used in machine construction and in the chemical and petroleum refining industries. The technical result of the proposed invention is an increase in the micro-strength and crack resistance in the thin-layer ceramic coating which is crucial to the durability of the ceramic material. The invention in essence involves the following steps: material, specifically an aluminium-containing metal composition which also contains copper in a quantity of 4-10 % and forms one electrode, is treated. The second electrode is an electrolytically insoluble metal. The electrolyte is an aqueous solution of an alkali (1-6 g/l) and water glass (4-6 g/l), to which is added a powder consisting of SiO2 (90%) and Al2O3 (10%), with a degree of dispersion of 1-10 mu m at a concentration of 0.5-2.0 g/l. The surface of the aluminium-containing metal composition is treated in an anode-cathode regime, the ratio of anode current to cathode current being I=1.1-1.2, for a period of 60-180 minutes. The thin-layer ceramic coating thus obtained, based on globular thin-layer ceramic material consisting either in part or entirely of clusters of filamentary alpha -Al2O3 crystals present in the fine-crystalline gamma -Al2O3/mullite 3 Al2O3 * 2SiO2 matrix, is characterised by a wear intensity I of 10<-10>-10<-12>, a friction coefficient f of 0,010-0,035, a microhardness H of 16-18 GPa, and a critical cracking load P of 2.5-3.0 N. |
