The demand for decreasing CO2-emission and harmful material content of the exhaust gas of passenger cars requires the improvement of the entire powertrain including the applied lubricants. One of the possible future engines lubricant can be the nano-sized ceramic particles, which can provide positive tribological properties also in the presence of nonmetallic surface materials. This paper presents the experimental investigation of ZrO2 nanoceramic powder as a lubricant additive. The tribological performance of the lubricant samples was experimentally investigated on a ball-on-disc translation tribometer. An optimum concentration was found at 0.4 wt%, where the wear scar diameter on the ball specimen was reduced by more than 40% compared to the reference sample. The SEM-analysis confirmed the mending mechanism theory: nanoparticles were revealed to aggregate between the asperities resulting in a significantly smoother contact surface.

The continuous tribological development of engine lubricants is becoming more and more vital due to its fuel efficiency improvement and lifetime increasing potential. The antiwear additives play a high role in the lubricants to protect the contacting surfaces even in the presence of thinner oil film. Nanoscale spherical particles in the lubricant may increase the necessary protecting effect. This paper presents the results of the experimental tribological investigation of nanoscale spherical Y2O3 (yttria) ceramic particles as an engine lubricant additive. The ball-on-disc tribological measurements have revealed an optimum concentration at 0.5 wt% with about 45% wear scar diameter and 90% wear volume decrease, compared to the reference, neat Group III base oil. The high-magnitude SEM analysis revealed the working mechanisms of yttria: the particles collected in the roughness valleys resulted in a smoother contacting surface, they were tribo-sintered and they have also caused slight plastic deformation of the outer layer of the metallic surface.

Due to the continuously increasing requirements of the internal combustion engines, the lubricants and their additives have to be further developed. One possible solution is the application of ceramic nanoparticles as friction modifier and wear decreaser additives. This paper presents the tribological investigation of cupricoxide (CuO) nanoparticle mixed in neat Group 3 base oil. To analyse its properties, simplified ball-on-disc friction experiments were carried out in the tribological laboratory in the Széchenyi István University in Győr, Hungary. The arisen wear scars were analysed with different, highresolution microscopes to understand the working mechanism of the nanoparticles. The results have indicated an optimum concentration of nanoparticles at 0.5wt% where both the average friction coefficient and the wear scar diameter were reduced by 15%. The microscopical investigation revealed the reduction of copper material from the CuO material, and it has mended to the rubbing surface forming a protective film on the metal surface.

Long-term environmental goals will motivate the automotive industry, component suppliers, and lubricating oil developers to reduce the friction of their tribosystems to improve overall efficiency and wear for increased component lifetime. Nanoscale ceramic particles have been shown to form a protective layer on components’ surface that reduces wear rate with its high hardness and chemical resistance. One such ceramic is yttria (Y2O3), which has an excellent anti-wear effect, but due to its rarity it would be extremely expensive to produce engine lubricant made from it. Therefore, part of the yttria is replaced by zirconia (ZrO2) with similar physical properties. The study presents the result of the experimental tribological investigation of nanosized yttria–zirconia ceramic mixture as an engine lubricant additive. Yttria-stabilized zirconia (YSZ) nanoparticle was used as the basis for the ratio of the ceramic mixture, so that the weight ratio of yttria–zirconia in the resulting mixture was determined to be 11:69. After the evaluation of the ball-on-disc tribological measurements, it can be stated that the optimal concentration was 0.4 wt%, which reduced the wear diameter by 30% and the wear volume by 90% at the same coefficient of friction. High-resolution SEM analysis showed a significant amount of zirconia on the surface, but no yttria was found.

Decreasing harmful emissions of vehicle engines is becoming more and more challenging due to stricter standards. A possible solution is to improve the tribological attributes of lubricants, which can be achieved through the application of appropriate additives. According to preliminary studies conducted by the authors, ZrO2 (zirconium-dioxide) nano-sized ceramic particles as lubricant additives have overwhelmingly positive tribological attributes in the presence of non-metallic superficial materials. Additive concentration, as well as cross-effects with other additives were investigated in order to determine a formulation resulting in optimal tribological attributes. In this paper, the experimental investigation of ZrO2 nano-ceramic powder as a lubricant additive is presented. The tribological performance of individually samples were experimentally investigated on a ball-on-disc translational tribometer. The experiments revealed an optimal additive content of 0.3 wt%. Increasing the quantity of additives further ruined friction and wear properties of the examined tribological system.