Cathode material and pulsed plasma treatment influence on the microstructure and microhardness of high-chromium cast iron surface

The article presents an analysis of the cathode material and the pulse plasma treatment mode influence on the surface microstructure and microhardness of high chrome (15% Cr) cast iron. The methods of metallographic analysis and microhardness measurements were used. It has been shown that pulsed plasma treatment at 4 kV voltage with the use of the electro-axial thermal accelerator results in surface modification with high microhardness 950-1050 HV50, and in the formation of the coating due to the transfer of the electrodes material. The specific features of using different cathode materials have been systematized. It has been found that graphite electrodes are not recommended to be used due to their low strength and fracture under plasma pulses. In case of using tungsten cathode a coating of small thickness (20-30 microns) and having cracks has been formed on the specimen surface. The most expedient is to apply the electrodes with low melting point (such as killed St.3), which provides a high-quality state of treated surface and formation the protective crack-free coating of 80-100 microns thick. It has been found that as a result of the plasma pulsed treatment the enrichment of coating with carbon is likely to occur that results in microhardness increase. The prospects of this technology as well as its shortcomings have been described