Mara Kandeva

Wear resistance of WC/Co HVOF-coatings and galvanic Cr coatings modified by diamond nanoparticles

The efforts in the recent 20 years are related to search of ecological solutions in the tribotechnologies for the replacement of galvanic Cr coatings in the contact systems operating under extreme conditions: abrasion, erosion, cavitation, corrosion, shock and vibration loads. One of the solutions is in the composite coatings deposited by high velocity gas-flame process (HVOF). The present paper presents comparative study results for mechanical and tribological characteristics of galvanic Cr coatings without nanoparticles, galvanic Cr coatings modified by diamond nanoparticles NDDS of various concentration 0.6; 10; 15 и 20% obtained under three technological regimes, and composite WC-12Co coating. Comparative results about hardness, wear, wear resistance and friction coefficient are obtained for galvanic Cr-NDDS and WC-12Co coatings operating at equal friction conditions of dry friction on abrasive surface. The WC-12Co coating shows 5.4 to 7 times higher wear resistance compared to the galvanic Cr-NDDS coatings.

The influence of the valena metal-plating additive on tribotechnical characteristics of the Steel–Bronze tribological system

The paper considers a change in the coefficient of friction and the temperature distribution in the contact zone of the steel–bronze tribosystem. Investigations were carried out by the shaft–bushing system for three values of the load in the mixed-to-boundary lubrication regime with SAE 80W transmission oil without and with Valena additive. It is found that the additive presence in oil decreases the coefficient of friction by 11–21%, depending on the applied load. At the same time, the maximum decrease in the coefficient of friction is observed at a maximum applied load of 1500 N.