FEATURES OF THE FORMATION OF SURFACE LAYERS DURING PLASMA HEATING OF TIN BRONZE PRE-COATING

We experimented with obtaining surface layers by plasma heating of a pre-coating of tin bronze (PRV-BrO10 alloy) of various thicknesses (0.25; 0.5; 1.00 mm) when exposed to various currents (100; 140; 160 A). The resulting layers have different depths of the hardened layer and different structures. With a pre-coating layer thickness of 0.25 and 0.5 mm, high current easily causes defects. With a thicker pre-coating layer (1 mm), the dissolution of tin bronze into steel is limited. Low current of the plasma arc (100 A) limits the diffusion and transformation of the molten pool sufficient to saturate the thick pre-coating layer (0.5 and 1 mm) with alloying elements. Saturated zones rich in iron are represented by high dispersion and microhardness, which is mainly in the range of 400–600 HV.