Laws of Formation of Electrospark Coatings from Alloys of the Ni – Cr – Al – Y System

The main parameters of electrospark alloying of steel 45 with anodes made from Ni – Cr – Al – Y alloys have been investigated. The anodes were fabricated by casting and hot pressing. The highest values of the mass transfer coefficient were observed in the case of electrospark alloying with hot-pressed alloys. Microstructure and x-ray phase analyses of electrospark coatings revealed the presence of solid solutions based on nickel, iron, chromium as well as intermetallic compounds. Coatings obtained by electrospark alloying with hot-pressed alloy are more wear-resistant than are coatings obtained by alloying with cast alloys.     

Changes in Structure and Physicochemical Properties of Spark Coatings Based on TiN and TiB2 after Treatment with Concentrated Solar Radiation

Studies have been made on the structure and properties of spark coatings made of TiN and TiB₂ on steel U8 after treatment with concentrated solar radiation. It is found that the absorption capacity of the steel raised by a factor 2–3. The concentrated radiation reduces the coefficient of friction of the spark coatings made of TiN and TiB₂ by a factor 1.4, while the wear rate is reduced by a factor 1.6–2 by comparison with the untreated material. __________ Translated from Poroshkovaya Metallurgiya, Nos. 7–8(444), pp. 64–69, July–August, 2005.     

Phase composition of the surface layers of high-speed cutting steel after electrospark alloying and laser treatment

Due to the metallurgical processes occurring under the action of laser irradiation, which are accompanied by convectional mass transfer, phase formation, and the interaction of alloying elements with the base material and elements of the environment, tungsten carbide fully dissolves in the steel melt in the case where alloying was carried out with alloys based on this carbide. Moreover, the refractory component of tungsten-free electrode materials stayed completely unaltered. by partially losing a non-metal. These transformations occur under nonequilibrium conditions. To improve the tribotechnical properties and durability of a high-speed cutting steel upon cutting, it is reasonable to alloy its surface layer with elements and compounds which form stable oxides strongly bound to the base. Frantsevich Institute of Problems of Materials Technology, the Ukrainian Academy of Sciences, Kiev. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 36, No. 1, pp. 83–86, January–February, 2000.     

Electrospark Graphite Alloying of Steel Surfaces: Technology,Properties, and Application

Regularities in the influence of processing time and discharge energy on the thickness, microhardness and roughness of carburized cases during electrospark graphite alloying of steel surfaces are studied and quantitative data on them are obtained. The thickness of the strengthened layer increases with gains in discharge energy and alloying time. Specimens of 40Kh, 38KhMYuA, 40KhN2MYuA, 30Kh13, Armco iron, 12Kh18N10T steels and 20 steel, as well as EGe-4 graphite are studied. The tests were carried out using the following devices: EILV-8А, EILV-9, Elitron-22А, and Elitron-52А, which provide discharge energy in the range from 0.1 to 6.8 J. Experiments show that case depth and microhardness under the same process conditions are differ significantly for various steel grades. Case depth increases with higher initial carbon contents in steel. The greater the discharge energy, the greater this difference is. Wear tests show that the method of nonabrasive ultrasonic finish processing after graphite electrospark alloying is effective, and it allows increases in the wear resistance of specimens by a factor of 7.8 for 40Kh steel and by a factor of 11.5 for 12Kh18N10T steel. Research confirms that the stage electrospark alloying of the surface of a specimen after carbonization with a graphite electrode effectively decreases roughness. Discharge energy is lowered at each stage. The stage graphite electrospark alloying of the 38KhMYuA steel case allowed decreases in the surface roughness from R _а = 11.9–14.0 μm to 0.8–0.9 μm. Industrial tests show that graphite electrospark alloying offers can accomplish a number of practical tasks.     

The influence of burnishing on the properties of electrospark coatings

Translated from Fiziko-khimicheskaya Mekhanika Materialov, Vol. 26, No. 5, pp. 119–120, September–October, 1990.     

Effect of Pulsed Laser Radiation on the Properties of Resistive Thick Films Based on Nickel and Barium Borides

We have used atomic force microscopy to study the surface morphology of resistive thick films based on powders of nickel and barium borides and a glass binder, treated with laser radiation. We used x-ray phase analysis to study the phase composition of these films. We have observed a change in the surface morphology, the phase composition, and the electrical resistance of the studied films as a function of the laser radiation energy.     

Structure and properties of resistive thick films after laser treatment

We have studied the influence of laser radiation on the structure and electrophysical properties of resistive thick films based on BaB₆-LaB₆ solid solution. It has been shown that, in the course of laser treatment in the millisecond range, barium and lanthanum diffuse into the substrate, and micro-and nanosecond laser radiation leads to the breakup of current-conducting chains and the formation of domains with discrete structure. We have carried out a differential analysis of voltampere characteristics and determined the temperature dependences of electrical resistance R and resistance temperature coefficient. Laser treatment in the micro-and nanosecond ranges slightly increases the electrical resistance, which can be used for the precision treatment of thick films. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 43, No. 6, pp. 79–85, November–December, 2007.     

Properties of plasma-sprayed coatings treated by laser radiation

The effect of laser treatment on the properties of plasma coatings made from the self-fluxing alloy PGSR-3 with additions of titanium carbide, heat-resistant Ni?Cr?Al?Y alloy, and clad Ni?Al powders was investigated. Laser treatment increased the adherence of the coating to the substrate, density of the surface layers, and promoted the formation of structures with a uniform distribution of alloying elements.