METHOD OF PRODUCING DECORATIVE COATINGS ON ARTICLES FROM ALLOYS OF VALVE METALS Russian patent published in 2024 - IPC C25D11/18 

FIELD: various technological processes.

SUBSTANCE: method of producing decorative coatings on articles from alloys of valve metals relates to surface treatment and can be used in machine building and related industries. Method is promising for processing of products from alloys of aluminium, magnesium, titanium and other metals of valve group used in harsh climatic conditions, including at high temperature difference and high ambient humidity. According to the proposed method, first, articles from alloys of valve metals are subjected to jet-abrasive processing, which provides surface roughness of Ra 2.5–5.0, then treated with microarc oxidation in a solution of potassium hydroxide 8–10 g/l or caustic soda 7–9 g/l, having temperature of 35–45 °C, at AC density of 12–40 A/dm² for 4–8 minutes, then articles are heated to 330–1,000 °C with holding for 2.5–5 minutes, wherein heating temperature should be at least 15–20 °C is lower than the melting point of the alloy of the article, then, on the surface of the products, a paint material with the required decorative characteristics is applied in two steps — first, 20–25% of the paint material is applied at viscosity of 40–70 cSt, then 80–75% of paint material is applied at viscosity of 80–110 cSt, and then final drying is carried out.

EFFECT: jet-abrasive processing together with micro-arc oxidation and subsequent heating with observance of the above parameters provides a rational combination of roughness of surfaces of articles and porosity of oxide coatings formed on them; this, in turn, enables to achieve high adhesion of paint coatings to surfaces of articles, as well as high durability of paint coatings and the articles themselves.

1 cl, 1 dwg