Modified Tool Steel Surfaces by Electrical Discharge Treatment in Electrolyte

Of great importance for tools performance and working capacity are the tool steels surface properties such as high hardness and wear resistance which can be significant improve by surface modification. Basic techniques with wide application in this area are PVD and CVD technologies for thin films deposition of hard materials including nitrides, carbides, borides and carbonitrides. In the present work are described the opportunities of electrical discharge treatment in a suspension of boron carbide in electrolyte as a process for surface modification of tool steels and obtaining of layers with high hardness, wear resistance and corrosion resistance. The modification goes by a high energy thermal process in a very small volume on the metallic surface involving melting, vaporisation, activation and alloying in electrical discharges, and after that cooling of this surface with high rate in the electrolyte. Metallic surface after electrical discharge treatment in electrolyte has a different composition and structure in comparison with the metallic matrix which determines different properties. The modified surfaces are investigated by XRD, SEM, AFM, light microscopy and micro hardness testing.