The use of powder materials of highly hard compounds for the formation of electric spark coatings for various functional purposes

Abstract

Electric spark alloying of solid surfaces is a promising direction for increasing the performance properties of materials. Formation of superhard material coatings on a substrate allows to significantly increase hardness, wear resistance, resistance to high temperatures and pressure, and improve the performance characteristics of products by 1.5–5 times. This is due to the formation of various multicomponent structures in electric spark coatings that have increased strength and tribotechnical characteristics. The aim of the work was to study the structure and physical and mechanical properties of electric spark coatings obtained from powder materials. Various powder charge compositions and electric spark discharge parameters were used to form the coatings. The coatings were formed under standard climatic conditions by combining powder materials based on titanium carbide (TiC), aluminum (Al), carbon (technical graphite), titanium nitride (TiN), aluminum nitride (AlN) using the developed technology. The strength and adhesion properties of coatings obtained by the electric spark alloying method were studied. The studies to determine the adhesion characteristics using scratch analysis and Rockwell methods showed that coatings based on TiN+Al compounds have high adhesion strength. It was found that in TiN+Al coatings, electric spark alloying can lead to the formation of MAX phases and high-entropy compounds,which has a positive effect on the physical and mechanical properties of the formed coatings. The microhardness of the studied coatings is increased by 2–4 times compared to the original titanium substrates. The dependence of the coating microhardness on the indenter penetration depth was studied. The dependence of the strength characteristics on the indenter penetration depth of the TiC+Al electric spark coating (0.9 J) formed on the VT1 titanium alloy is nonlinear with an extremum in the region of a coating thickness of 9–10 μm. The strength characteristics of electrospark coatings formed by a contactless method from refractory metals were investigated. The possibility of forming coatings from silicate ceramics with increased values of microhardness and adhesive strength was established.