Lubricating problems are common in many engineering applications, such as aerospace, ground mechanical equipment, and large aircraft carriers. Moreover, the high-performance lubricating materials are the key to ensure high running precision and stability for mechanical systems. With the rapid development of modern technology, various lubricating materials have been developed for different machineries. These developments are geared toward improving the property of materials and allowing them to surmount severe challenges under extreme conditions (e.g., high/low temperature, special media, and unfavorable atmosphere) in the fields of aviation, space, nuclear energy, and microelectronics. The lubricating materials corresponding to the required conditions in these fields must be capable of working in corrosive environments and high/low temperatures for a long time. However, because the conventional lubricating materials cannot satisfy these application requirements, lubricating materials are currently facing a series of challenges [1, 2].
In recent years, much effort has been directed toward preparing high-performance materials and coatings for tribological applications, such as laminated-graded self-lubricating composites [3, 4], composite-lubricating coatings [5], and DLC films with surface texturing [6]. In addition, nanomaterials and nanostructures, because of their special dimensional effects, reveal totally different tribological and mechanical properties compared with traditional materials [7, 8]. The combination of nanomaterials and lubricating composites is a promising way to achieve the optimization of lubricating materials [9]. Meanwhile, the emergences of new preparation technologies [10] and theoretical approaches [11] have hastened the development of an increasingly large number of new lubricating materials and thus speeded up the industrialization process of these materials.
In this special issue, five papers are devoted to the mechanical and tribological performances of nanomaterials and films. The carbon nanolayer, remained on the surface of Ti6Al4V alloy after ion implantation, was proved to have an influence on friction reduction due to the self-lubrication property of the carbon nanolayer. Dual-coated TiO2 nanoparticles as water based lubricant additive and cutting fluids additive provided excellent tribological properties, which might be ascribed to the forming of a dynamic deposition film during rubbing process according to surface analysis. For DLC films, nanotribological properties such as H (Nanoindentation hardness) and nanowear resistance were highly correlated with ID/IG ratio and highly dependent on the films’ nanostructures. Hard and soft multilayered SiCN nanocoatings with high hardness and toughness were prepared by magnetron sputtering. Increased deformation accommodation was achieved for such alternate hard and soft layers as the thin hard layers slide relative to each other due to shear deformation of low modulus layers. This special issue also contains a very interesting hypothesis about developing an elastic property analysis model suitable for three commonly used fabric liners through a theoretical analysis of the elastic properties.
We hope that readers will find in this special issue not only accurate data and updated reviews on the tribological behavior of advanced materials, but also important guidance for the optimization of the advanced lubricating materials.
Yongsheng Zhang
Tianchang Hu
Xianjin Ning
Qi Ding