Influence of Ag Content and Nanograin Size on Microstructure, Mechanical and Sliding Tribological Behaviors of Ag-DLC Films

Abstract

Diamonds like carbon (Ag-DLC) films of nine Ag contents were deposited on (100) Si substrate in a mid-frequency dual-magnetron system. The influence of Ag content and nanograin size on the microstructure, mechanical properties and sliding tribological behaviors of the films has been investigated. It is found that (i) the Ag nanocrystallites were dispersed in the amorphous DLC matrix, and increasing Ag content resulted in an upward tendency of the Ag nanocrystallite size; (ii) the films with Ag content ranging between 3.3-11.4 at% and with Ag nanograin sizes in range of 5.4-16.8 nm exhibited higher hardness, lower intrinsic stress, better adhesion, and lower friction coefficient and wear rate as compared with those of 14.7-23.6 at% Ag content and 19.7-34.7 nm nanograin sizes; and (iii) the best combined properties were achieved for the film deposited with 8.7 at% Ag and with grain size 12.9 nm.

Attempting AG-Doped Diamond-Like Carbon Film to Improve Seal Performance of Hydraulic Servo-Actuator

“…3.8 × 10 −9 mm 3 /mN) among the films in this experiment. Comparing with the optimal Ag-DLC film prepared by M. Hua et al [8], and under the same load and sliding distance, the wear rate obtained herein was ca. 16 times lower than that reported by these authors (6.48 × 10 −8 mm 3 /mN).…”

“…As shown in Figure 7a,b, the G peak shifts from 1500 cm −1 (undoped DLC film) to 1550 cm −1 (no wear film), and the D peak shifts from 1395 cm −1 (undoped DLC film) to 1380 cm −1 (no wear film). This shift of the D peak moves toward a lower wavenumber while the G peak moves toward a higher wavenumber, which may result from the doping of Ag in the DLC film [8,20]. Consequently, the I G /I D ratio increases from 1.4 (undoped DLC film) to 1.5 (no wear film), and the content of sp 3 -C decreases from 41.7% for undoped DLC film to 35.8% for no wear film.…”

“…Overall, the hardness and intrinsic stress of the films depend on the combined action of these two factors. An optimum content of Ag doped in an amorphous carbon matrix with a suitable crystallite size is likely to optimize the mechanical properties of the films [8], providing them with high hardness and low intrinsic stress, and in turn results in good toughness properties. This improved toughness may prevent seal leakage issues caused by the high oil pressure on the coated piston rod.…”

“…None carbide-forming metals such as Ag may bring hope to replace their carbide-forming counterpart. Our previous Ag-DLC research [8] indicates that a soft and ductile Ag, embedded into the amorphous carbon matrix, may improve the tribological properties by lowering brittleness rates. Unfortunately, a systematic investigation is rare to see in the literature for using Ag-DLC film to improve the seal performance of a hydraulic servo-actuator.…”

Synthesis of Ag-doped hydrogenated carbon thin films by a hybrid PVD–PECVD deposition process

“…Me-DLC films have been synthesized by different deposition methods, thereby providing a wide range of different film properties. Yu et al (2009) studied non-hydrogenated Ag-DLC films prepared by a mid-frequency dual-magnetron system and they investigated influence of Ag content and grain size on microstructure. They found that the Ag nanocrystallites were dispersed in the DLC matrix, and increasing Ag content resulted in an increase of the Ag nano size.…”