Title:
THIN-LAYER CERAMIC COATING AND METHOD OF PRODUCING THE SAME
Document Type and Number:
WIPO Patent Application WO/1997/003231
Kind Code:
A1
Abstract:
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.
Inventors:
FEDOROV VLADIMIR ALEXEEVICH DI
Application Number:
PCT/RU1996/000185
Publication Date:
January 30, 1997
Filing Date:
July 10, 1996
Export Citation:
Assignee:
FEDOROVA LUDMILA PETROVNA & HF (RU)
International Classes:
C25D11/02; C25D11/04; C25D11/34; C25D15/00; (IPC1-7): C25D11/02; C25D15/00
Foreign References:
| US5082536A | 1992-01-21 | |||
| DE4027999A1 | 1991-03-14 | |||
| US4222828A | 1980-09-16 | |||
| US4886583A | 1989-12-12 |
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