The analysis of the self-lubricating behavior and local failure mechanism of silver-rich solid film

Abstract

Purpose The main aim of this paper was to study the self-lubricating behavior and failure mechanism of silver-rich solid film for in-depth analyzing of the friction and wear property of TiAl-10 wt. per cent Ag self-lubricating composite. Design/methodology/approach The friction and wear property of TiAl-10 wt. per cent Ag self-lubricating composite sliding against Si3N4 ball was tested under the testing conditions of ball-on-disk wear system. Field emission scanning electron microscopy and electron probe microanalyzer were used to analyze the surface morphology of silver-rich solid film. The main element contents were tested by energy dispersive spectroscopy. Silver phase on wear scar could be well identified using X-ray photo-electron spectroscopy. The theory calculation of shearing stress on wear scar was executed to discuss the local failure mechanism of silver-rich solid film. The lubricating role of silver was also discussed to analyze the anti-friction and anti-wear behavior of silver-rich solid film. Findings The friction coefficients and wear rates of TASC gradually reduced at 0-65 min, and approached to small values (0.31 in friction coefficient and 3.10×104 mm3N-1m-1 in wear rate) at 65-75 min. The excellent friction and wear behavior of TASC was mainly attributed to the lubricating property of silver-rich film at 65-75 min. At 12→20 N, surface shearing stress increased up to 146.31 MPa, and exceeded more than the shearing strength (125 MPa) of silver-rich film, which caused the propagating of fatigue crack and the destroying of silver-rich film, leading to high friction and severe wear. Originality/value It is important that the self-lubricating behavior and local failure of solid film is explored for further understanding the friction and wear property of TiAl alloys.

Investigations on the mechanics and tribology of multilayer graphene nanosheet in TiAl aviation composites

“…To improve the friction and wear behaviors of these components, most researchers have focused on preparing self-lubricating samples containing silver. [6][7][8] Xu et al 6 studied the effect of the migration of silver atoms on the tribological behaviors of materials. They found that the silver atoms in TA-based materials migrated to the wear scars and induced the formation of a silverrich film, that led to low friction and wear.…”

“…But, the application of high loads on the silver-rich film resulted in significant peeling and surface cracks, because of the weak bearing capacity of the film. 7 In comparison to the silver, multilayer graphene nanosheets were highly reinforced materials, [9][10][11][12][13][14][15][16] and the nanosheets selected by Xie et al 9 acted as effective fillers for improving the mechanical and tribological properties of ceramic-based coatings. According to studies by Balog et al 10 and Kwon et al, 11 graphene improved the mechanical and tribological behaviors of the materials owing to the reduction of the atomic layers.…”