METHOD OF APPLYING PROTECTIVE DIFFUSION COATINGS TO PRODUCTS FROM METAL AND ALLOYS Russian patent published in 2003 - IPC

FIELD: thermochemical treatment of metals and alloys. SUBSTANCE: invention may be used for intensification and regulation of temperature-timing characteristics of processes of formation of protective (functional) diffusion coatings, with preset properties on metal structural materials and products. Said invention is used in machine-building, automotive, tractor, aircraft industries, rocket manufacture, shipbuilding, power engineering and other industries. Method includes diffusion saturation of product surface layers with saturating elements from solid or vapor-gas phase and formation of external protective layer of chemical compounds of saturating elements with product metal and also formation of internal layer of solid solution of saturating elements in product metal in presence of furnace working volume of substances-activators liberating gaseous hydrogen fluoride. Protective diffusion coatings to products from metals and alloys are applied due to the fact that liberated gaseous hydrogen fluoride by substances-activators act on boundaries of grains of protective coating formed on product by building-up in furnace working volume of partial pressure of hydrogen fluoride of 10^-2-10^-1 bars and introduction into protective coating of hydrogen fluoride in amount of 10^-2-10^-1 % of final weight of protective coating. Additionally regulated by building-up in furnace working volume of various values of partial pressure of hydrogen fluoride within 10^-3-10^-1 bars are ratios of thicknesses of external protective layer of chemical compounds (intermetallic compounds) of saturating elements with product metal and internal layer of solid solution of saturating elements in metal. Substance liberating gaseous hydrogen fluoride is used in the form of one of substances containing fluorine and hydrogen , etc). Technical result of invention consists in provision of preset reduction of temperature-timing parameters of process and also definite functional properties of protective coating. EFFECT: accelerated diffusion of saturating element through formed protective coating of metal (alloy) of saturated product. 5 cl, 4 dwg