Quantum modelling of Lubrication Mechanism in Metal Forming Processes

Friction is a major issue in industrial activities, accounting for a loss of 5-7% of the gross national product in many developed countries 1-3. Therefore, multiple concepts and novel lubricant materials have been explored and optimized to eliminate unnecessary friction and wear in many manufacturing processes. However, the conventional lubricants cannot satisfy the demand of industrial practice, environmental sustainability, and wide working temperatures range. Therefore, in this thesis, two different types of lubricants have been investigated for their suitability in metal forming processes. The first one involves Silicate Glass lubricants for high-temperature application, and the second is MgAl layered double hydroxides (LDH) material for moderate temperature utilization. Inorganic glasses such as alkali phosphate, borate, and silicate, have been utilized as an effective lubricant for high-temperature operations. Experimental studies based on these lubricants have shown good performances in terms of friction reduction, antiwear function, and antioxidation, especially at elevated temperatures and under severe loads. However, the lubrication performance of glass lubricants still needs to improve to bolster their practical utilization in the industry. On the other hand, LDH is a new promising candidate for lubrication, which shows excellent friction reduction (even superlubricity) at room temperature and could potentially be applied for moderate temperature applications. However, most of the available experimental studies on LDH have been based on trial and error due to the lack of in-depth knowledge of the tribochemical reaction under the sliding contact. Therefore, a better understanding of the friction mechanism at the atomic scale of these materials would help direct future studies to design a new generation of lubricants for metal forming.