STUDY OF THE STRUCTURE AND PROPERTIES OF THE SURFACE OF HARD ALLOY VK10KS AFTER TWO-COMPONENT ELECTRICAL EXPLOSION TREATMENT WITH SYNTHETIC DIAMONDS

The article presents the results of studies of the VK10KS hard alloy after two-component electroexplosive treatment (EVL) with synthetic diamonds. Aluminum was used as the exploding conductor. The choice of aluminum is based on the experimental data of a number of researchers who note that in order to increase the strength properties of hard alloys at elevated temperatures, it is necessary that particles with a size of hundredths of a micron of ultrafine α-Al₂O₃ be present in the cobalt binder. Thus, the addition of aluminum to the bond significantly increases the hardness, wear resistance and bending strength. The essence of the EVL is the accumulation of energy by a battery of impulse capacitors up to 10 kJ and its subsequent discharge for 100 μs through a conductor that experiences explosive destruction. In this case, the treated surface is heated and saturated with explosion products, followed by self-hardening due to heat removal to the environment and deep into the material. To increase the hardening effect, a powder sample of synthetic diamond powder AC2 weighing 60 mg was additionally added to the explosion area. It was experimentally revealed that alloying the surface of the VK10KS hard alloy with the products of aluminum electric explosion with a sample of diamond powder did not lead to the formation of a hardened diamond-type layer. During processing, the diamond powder trans-formed into graphite. Despite the fact that the diamond layer was not formed, surface hardening of the VK10KS hard alloy occurred after the electric explosion of diamond powder with aluminum as a conductor. The thickness of the hardened surface layer is about 15 µm with a nanohardness of 24000 MPa, which is 2 times higher compared to the initial state. The increase in hardness is associated with the refinement of phases in the surface layer and the formation of W₂C and α-Al₂O₃ type carbides. The surface roughness of machined carbide inserts does not exceed the values corresponding to the technical requirements.The study of the cobalt binder in the heat-affected zone after two-component EVL found that the cobalt binder is additionally alloyed with tungsten, carbon, aluminum, which are part of the explosive materials and the base. Additional alloying of the cobalt binder will lead to its hardening, which will positively affect the service life of tungsten carbide hard alloys in general.

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