Abstract
Understanding the complex nature of wear behavior of materials at high-temperature is of fundamental importance for several engineering applications, including metal processing (cutting, forming, forging), internal combustion engines, etc. At high temperatures (up to 1000 °C), the material removal is majorly governed by the changes in surface reactivity and wear mechanisms. The use of lubricants to minimize friction, wear and flash temperature to prevent seizing is a common approach in engine tribology. However, the degradation of conventional liquid-based lubricants at temperatures beyond 300 °C, in addition to its harmful effects on human and environmental health, is deeply concerning. Solid lubricants are a group of compounds exploiting the benefit of wear diminishing mechanisms over a wide range of operating temperatures. The materials incorporated with solid lubricants are herein called ‘self-lubricating’ materials. Moreover, the possibility to omit the use of conventional liquid-based lubricants is perceived. The objective of the present paper is to review the current state-of-the-art in solid-lubricating materials operating under dry wear conditions. By opening with a brief summary of the understanding of solid lubrication at a high temperature, the article initially describes the recent developments in the field. The mechanisms of formation and the nature of tribo-films (or layers) during high-temperature wear are discussed in detail. The trends and ways of further development of the solid-lubricating materials and their future evolutions are identified.
Highlights
A significant increase in the number of operations performed at high temperatures (HT~upto 1000 ◦ C) has led to an exponential growth of interest in the field of hot tribology (Figure 1a)
Many components function beyond a normal temperature range, unfolding numerous tribological complications, pose a substantial uncertainty in material reliability and performance due to enhanced friction and wear
Irrespective of the chosen manufacturing process for material fabrication, low and steady friction in addition to low wear rates must be demonstrated at a wider range of temperatures since the work piece employed during operations can extend to or beyond ~1000 ◦ C [7]
Summary
A significant increase in the number of operations performed at high temperatures (HT~upto 1000 ◦ C) has led to an exponential growth of interest in the field of hot tribology (Figure 1a). In the framework of industrial applications, such as HT forming, forging, stamping, a cutting, solid-lubricating material is to minimize friction and wear, and deliver chemical, including areas of relative motion in engines, etc., the foremost importance for a corrosion, thermal, and mechanical stability. Irrespective of the chosen manufacturing process for material fabrication, low and steady friction in addition to low wear rates must be demonstrated at a wider range of temperatures since the work piece employed during operations can extend to or beyond ~1000 ◦ C [7] This demands the synergetic effect of several solid lubricants in order to achieve a low friction and wear at a large scale of operations can extend to or beyond ~1000 °C [7]. A summarized range of working temperature for various SLs material) are shown ingraph
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