NANOSTRUCTURED COMPOSITE MATERIAL BASED ON BORON CARBIDE AND THE METHOD OF ITS OBTAINING Russian patent published in 2017 - IPC C04B35/563 C04B35/573 B82Y40/00 

FIELD: chemistry.

SUBSTANCE: invention relates to a nanostructured composite material based on reactive boron carbide (B4C), which has high strength, hardness, modulus and specific rigidity in combination with a low density value designed to create lightweight ceramic armour elements in armour designs with a high degree of protection, as well as for the manufacture of wear-resistant products. A nanostructured composite material comprising a matrix consisting of uniformly distributed phases of silicon carbide, silicon and a solid solution of boron and carbon in silicon, and at least 65 vol. % of a reinforcing filler made of boron carbide grains whose surfaces are almost completely surrounded by a matrix and not exposed of the silicon melt in the impregnation process, in which the phase of silicon carbide is represented by grains, more than 90% of which are submicron and nanosized. The method of producing mentioned material comprises the steps of mixing the initial boron carbide powders of two or more fractions with an average grain size of the largest coarse fraction not exceeding 120 mcm and a carbon source in the form of an organic temporary binder and nanosized technical carbon with a specific surface area of at least 100 m²/G and an ash content of not more than 0.05 wt %; moulding the resulting mixture; carbonization of the organic binder and impregnation of the porous billet with a silicon melt containing additional boron elements and, optionally, carbon. The process of impregnating the preforms with a silicon melt is carried out in the temperature range of 1450-1500°C. The ratio of the average sizes of the initial grains of boron carbide of the three fractions is 14:6:1, with a ratio of their volume contents, respectively, of at least 3.5:1.0:1.5. The mentioned material has a modulus of elasticity of at least 400 GPa, a strength of at least 280 MPa, a specific hardness of at least 15.1×10⁶ m.

EFFECT: improved properties.

7 cl, 7 ex, 1 tbl, 2 dwg