Thermal stability of Si/SiC/ta-C composite coatings and improvement of tribological properties through high-temperature annealing

Abstract

We report the structure, mechanical properties, thermal stability, and durability of Si/SiC/ta-C composite (Si–ta-C) coatings fabricated using simultaneous filtered cathodic vacuum arc deposition and direct current unbalanced magnetron sputtering. Si concentration of 1.25–6.04 at.% was achieved by increasing the unbalanced magnetron sputtering power from 25 to 175 W. Si addition provided functionality to the coating, such as heat resistance, while retaining the high hardness of ta-C coatings. The Si–ta-C coatings were stable up to 600 °C regardless of the Si content, while the coating containing 3.85 at.% Si was stable up to 700 °C. The friction behavior and mechanical properties were dependent on the coating film before and after annealing at 100–200 °C; however, annealing at 300–400 °C decreased disk wear and increased counterpart wear due to an increase in film hardness on account of an endothermic reaction that increased the number of Si–C bonds. This indicates that the basic hardness characteristics of the ta-C coating and the high-temperature structural change of the Si–ta-C coating are important for ensuring high-temperature durability. These characteristics were verified through the low coefficient of friction and wear rate of the 1.25 at.% Si–ta-C coating after annealing at 500 °C.

Superlubricity with Graphitization in Ti-Doped DLC/Steel Tribopair: Response on Humidity and Temperature

“…Although some authors point out that the flash temperature is not high in the super-lubricated state of DLC, , the formation of dangling bonds by the wear and shear process provides support for sp 2 bonding even at low flash temperatures. Some researchers argued that the frictional heat of DLC in a frictionless state was calculated by less than 10 °C at the contact spot. ,, Therefore, since the graphitization of DLC starts at more than 300 °C, , the structural change by friction-induced temperature rise can be a little welcome individually under the superlubricity state. The flash temperature or hot-spot temperature promotes the chemical reaction; however, we infer it is not essential for structural evolution.…”

“…Some researchers argued that the frictional heat of DLC in a frictionless state was calculated by less than 10 °C at the contact spot. 71,94,95 Therefore, since the graphitization of DLC starts at more than 300 °C, 96,97 the structural change by friction-induced temperature rise can be a little welcome individually under the superlubricity state. The flash temperature or hot-spot temperature promotes the chemical reaction; however, we infer it is not essential for structural evolution.…”

State-of-the-Art Developments in Advanced Hard Ceramic Coatings Using PVD Techniques for High-Temperature Tribological Applications

“…In recent years, numerous research reports have been made available on different hard coatings for elevated temperature tribological applications [14][15][16][17][18]. The tribological behavior of the coating under HT conditions is evidently different from that under room temperature conditions.…”

Active control of Lubricant Flow Using Dielectrophoresis and Its Effect on Friction Reduction

“…From the past to the present, hard coatings have been a very important technology in the industrial field due to their tribological performance as well as cost efficiency. In recent years, DLC (diamond-like carbon) has become one of the hottest topics in the field of tribology due to its low friction [8][9][10][11], high hardness [12][13][14], wear resistance [15][16][17][18], and thermal stabilities [19][20][21]. The uniqueness of DLC, which dramatically changes its carbonaceous structure to sp 2 rich structure [22][23][24][25], can be viewed as an important concept of passive control of friction by frictional stimuli.…”