METHOD OF BORON-NITRIDING OF STEEL ARTICLES IN FLUIDIZED BED

摘要

FIELD: metallurgy, thermochemical treatment; applicable in mechanical engineering for increase of machine parts durability. SUBSTANCE: method includes heating and saturation of steel articles which are carried out in ammonia atmosphere. In so doing, during heating at temperature of 350-850 C, steel articles are allowed to stand for 2-30 min. Saturation is effected at temperature of 600-1000 C in saturating mixture containing the following components, mas.%: boron carbide, 1-50; nickel oxide, 0.05-5; cuprous oxide, 0.05-5; ammonium chloride, 0.01-1; potassium tetrafluoroborate, 0.01-1; corundum, 38-98.92. Before article cooling, gaseous products are pumped-out. Technical result consists in that method of boron-nitriding of steel articles in fluidized bed as compared with prototype allows production of better quality boride layers of 120-200 mcm thick with microhardness of 14000 MPa, microembrittlement of 3 points, 100-mcm transition zone between boride layer and steel matrix, and microhardness of 7000 MPa, that increases wear resistance of steel articles by a factor of 5. EFFECT: increased resistance of boride coatings to wear. 1 tbl