INFLUENCE OF TWO-LAYER COATINGS OF THE 'DLC + TIN / ALTIN' ON THE TRIBOLOGICAL PROPERTIES OF OILS UNDER BOUNDARY LUBRICATION

The application of monocrystalline carbon to steel surfaces of rubbing bodies significantly increases the anti-friction and anti-wear properties of lubricants. (Research purpose) The research purpose is in choosing the optimal intermediate layer material based on the evaluation and comparison of the physical, mechanical and tribological characteristics of two-layer coatings obtained using titanium nitride and titanium aluminitride, respectively, as a solid intermediate layer, and compare them with each other. (Materials and methods) The cylindrical surfaces of 100Cr6 steel rollers with a diameter of 8 mm were coated with titanium nitride and titanium alumonitride, using the latest technologies, and on top of these coatings by pulsed condensation of carbon plasma with additional bombardment with argon ions - monocrystalline carbon. The micromechanical and microgeometric characteristics of the studied surfaces were evaluated using NanoScan-4D and SNeox devices. Pure base oil PAO-4, oil with the addition of oleic acid as a surface-active additive, and zinc dialkyldithiophosphate as a chemically active additive were used as a lubricant. (Results and discussion) The use of intermediate layers of titanium nitride and titanium aluminitride improves the adhesion of the carbon coating, which has a positive effect on its wear resistance. The main role in the antifriction effect of two-layer coatings is performed by a thin-layer carbon coating. (Conclusions) The article shows that the use of composite coatings from monocrystalline carbon + heat-resistant coating in friction units operating in the boundary lubrication mode serves as a reserve for improving the lubricating properties of oils, without requiring chemically active additives containing elements that negatively affect the environment. As an intermediate coating, the best result was shown by titanium aluminitride, it is more resistant to wear, and also provides lower friction.