Key Engineering Materials Vol. 901

Abstract: To transfer more power and use it in a heavy load environment, the contact surface between the ball and the track must bear great stress. The temperature always rises due to friction, which is more likely to cause problems of material deformation and fatigue failure. As a result, it will be a key technology to maintain a certain lubricating effect of the transmission components under the environment of heavy load and temperature rise. Through the analysis of friction coefficient and electrical contact resistance, the greases are used to test the lubricating effect of the transmission elements under the heavy load condition. The results will be helpful for the industry to use heavy load greases as a reference.

Abstract: Due to the booming development of the automation industry and the transportation industry, the mechanical components are prone to wear under long-term operating conditions. To improve the wear resistance, effects of the rolling directions on wear of the aluminum alloys are studied. An optical microscope is used to analyze the crystal phase, and the correlation between the crystal grains and the rolling direction is studied. This study can therefore establish a key technology for improving the wear resistance of aluminum alloys.

Abstract: Due to experimental limitations, sometimes it is challenging to tackle the thorough change in asperity characteristics (contact pressure, real area of contact, asperity radius), which demands a more suitable analytical model for prediction of such characteristics. This work demonstrates an approach for modeling sliding wear that provides an insight into the evolution of surface topography with operational cycles. The wear model is applied on various engineered surfaces to study the change in surface topography with wear cycles. It is concluded that different engineered surfaces nearly with same roughness demonstrate totally different behavior during sliding wear. It is observed that milled surface in comparison to turned, honed and grinding surfaces experiences minimum contact pressure due to very high correlation length. Within the range of wear cycles, maximum increase in the asperity radius is observed for milled surface.

Abstract: NbN/TiN, TiNb-N_X and CH-TiNb-N₁₂ coatings are deposited by RF magnetron sputtering to determine the tribological properties and corrosion resistance. ‘x’ is the flux rate for nitrogen and ‘CH’ signifies the addition of acetylene. In terms of the corrosion resistance, all the coatings have a similar corrosion potential and NbN/TiN multilayer coatings exhibit the lowest corrosion current. The NbN/TiN multilayer has a low pitting potential so severe pitting corrosion is observed on the surface. CH-TiNb-N₁₂ coating is most resistant to corrosion and exhibits no pitting before the test ends. In contact with counter-bodies with a Si₃N₄ ball or an AISI 52100 ball, a CH-TiNb-N₁₂ coating acts as a solid lubricant so the wear mechanism shows the least abrasion. The CH-TiNb-N₁₂ coating has the lowest wear rate and coefficient of friction for sliding against Si₃N₄ and AISI 52100 balls. The wear rate is respectively 3.2 and 6.8 times less than that for SKH51 substrate when sliding against Si₃N₄ and AISI 52100 balls. The results for this study show that a TiNb-N₁₂-CH coating has the best tribological properties and corrosion resistance.

Abstract: Mechanical properties of surface layers of aluminum alloys before and after friction tests are studied by nanoindentation. The influence of the composition of the alloys on these properties is analyzed. It is obtained that as a result of wear and tear, relatively compliant layer is formed on the surface of one of the alloys. Another sample demonstrates relatively rigid film at the surface of the friction path. Conclusions about different mechanisms of the wear and tear of alloys are made based on the analysis.