Tribological properties of polytetrafluoroethylene as additive in titanium complex grease

Abstract

Purpose -The purpose of this paper is to study, analyze and present the lubricating mechanism and tribological properties of two types of oil-based titanium complex grease containing Polytetrafluoroethylene (PTFE). Design/methodology/approach -Two types of oil-based sebacic acid/stearic acid titanium complex greases containing PTFE additive were synthesized using 3 L reaction vessel, and the base oils including neopentyl polyol ester and mixed oil of 650SN and neopentyl polyol (1:1.8). Frictionreduction, antiwear, and load-carrying properties of greases were evaluated using a four-ball tester, and their dropping point and penetration were characterized using relevant ASTM standards. Morphologies of wear scar and chemical states of typical elements on worn surfaces were characterized by means of scanning electron microscope and X-ray photoelectron spectroscopy, respectively. Findings -Tribological results show that titanium complex grease containing PTFE had better friction-reduction and antiwear properties than base grease. However, PTFE could not improve the load-carrying capacity of base grease. Moreover, a synergistic effect between deposited film and adsorptive film contributes to good tribological properties of titanium complex grease. Practical implications -Such a very useful lubricating material could be used in industrial applications including steel plants, power plants, packaging, and fertilizer industries. Originality/value -The lubricating mechanism of titanium complex grease containing PTFE was proposed by tribochemical analysis of worn surfaces. The mechanism should become the direction of the theoretical and applied research of grease in the future.

Tribological Investigations of Nano and Micro-sized Graphite Particles as an Additive in Lithium-Based Grease

“…This capability opens up the doors of formulating nano-greases efficiently with least possibility of agglomeration and sedimentation of nano-particles (NPs). Some solid lubricants (SLs) such as PTFE [8][9][10], MoS 2 [11], graphite [12,13], etc., have previously been shown as effective additives in grease formulations. Other lesser known SLs such as Talc [14], CaF 2 crystals [15], CaCO 3 [16], copper powder [17] and copper oxide [18] have shown some potential as anti-wear (AW), anti-friction (AF) and enhanced load-carrying capacity either alone or in combination.…”

Sustainable lubrication: low molecular weight PTFE micro-particles as extreme pressure additives for heavy duty grease applications

“…Researchers also have reported studies on the friction behavior and extreme pressure behavior of PTFE in lubricating greases (Aswath et al , 2007; Stolarski, 1976; Aswath et al , 2012; Chen, 2010; Stolarski and Olszewski, 1976; Figuo, 2012; Fan et al , 2014; Suresh et al , 2009; Trabelsi et al , 2016; Bagi and Aswath, 2015; Antony et al , 1994; Krawiec, 2011). Recently, Stolarski (1976), Stolarski and Olszewski (1976) studied the frictional mechanism of PTFE grease in journal bearing test rig.…”

“…They have shown that a thin layer of PTFE adheres to interacting surface due to adsorption of PTFE on metal subtract. Figuo (2012) studied the tribological properties of PTFE in Titanium complex grease. The study reported that at 2 Wt.% PTFE treat rate, reduced in the friction coefficient and improved the anti-wear property by 32.5% or 5.78%, respectively.…”

Combination of nanoparticles of graphite and hexagonal boron nitride as anti-wear and extreme-pressure additives- On exploring the possibility of synergism

“…A lot is reported on the tribo-performance enhancement of oils by inclusion of particles of solid lubricants (SLs), especially hexagonal boron nitride (hBN) [1][2][3][4][5][6][7][8][9], graphite [10,11], molybdenum disulphide (MoS 2 ) [12][13][14], Tungstendisulphide (WS 2 ) [15][16][17], polytetrafluoroethylene (PTFE) [18][19][20][21] etc. However, very few efforts are reported on investigating the combinations of such particulate additives of SLs showing synergism in functioning as anti-wear (AWA), antifriction (AFA) or extreme-pressure (EPA) in greases [22][23][24] and oils [24][25][26][27][28][29]. In case of oil soluble additives also are reported [30][31][32][33].…”