FIELD: process engineering.
SUBSTANCE: invention relates to chemical-thermal processing of steel articles, mainly, in production of water cooling, cold and hot water supply systems. Proposed method comprises the steps that follow. Diffusion medium is produced from the mix of powders containing passivating zirconium and silicon elements. Steel parts are brought in contact with diffusion medium. Steel articles and diffusion medium are heated to the temperature of reduction of said passivating elements, that is, to 900-950°C. Then, steel articles are cooled and removed from used diffusion medium containing said passivating elements. To produce said diffusion medium 60-65% of zirconium concentrate is used, containing zirconium and silicon as passivating elements, 15-20% of calcium fluorozirconate and 15-20% of pure fluorite. Obtained mix is changed into solid-fluid state to get fused fluorides and solid oxide solutions. Then, produced fused fluorides and solid oxide solutions are subjected to activation by current at 42-50 V for 15-30 minutes to get unstable solid zirconium and silicon oxide-based electrolyte containing fluorozirconate and calcium fluorides over boundaries of grains. Said electrolyte is subjected to low cooling to monolith state. Thereafter, said electrolyte is ground to powder. Steel parts are brought in contact with diffusion medium by filling produced powder mix in steel parts. Steel parts are cooled in diffusion medium to 400-450°C.
EFFECT: increased overhaul period of steel parts, efficient purity of protective layer depth.
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