The Tribology and Chemistry of Phosphorus‐Containing Lubricant Additives

Abstract

Phosphate esters, thiophosphate esters and metal thiophosphates have been used as lubricant additives for over 50 years. Recently, phosphorus-containing ionic liquids have emerged as a new class of lubricant additives. While the use of phosphorus compounds has been extensive, a detailed knowledge of how they work has been a much more recent development. In this chapter, the use of phosphate esters, thiophosphate esters, metal thiophosphates and phosphorus-containing ionic liquids as antiwear or extreme pressure additives is discussed. The primary emphasis will be on how they form a protective film, which is both durable and reduces friction. The first part of the chapter discusses the use of alkyl phosphates, triaryl phosphates and metal-containing thiophosphate esters with primarily iron-and steel-based bearing materials. The second part of the chapter examines phosphorus-containing ionic liquids and the challenges posed by new bearing materials with different surface chemistries.

Applications of Mass Spectrometric Techniques to the Analysis of Fuels and Lubricants

“…The sharp peaks appearing above the distribution are components of the phosphate ester antiwear additive. Phosphate esters form a surface layer that resists wear under boundary layer lubrication, such as during start-up of the process [41]. GC-MS can indicate additives present and also be an indicator of additive depletion or decomposition.…”

Effect of serum dilution fluids on the wear of unirradiated and high dose gamma-irradiated, vitamin E stabilized UHMWPE

“…PBS eliminated polyethylene transfer and wear, whereas substantial transfer and wear, although erratic, occurred with DW [19]. The difference may be attributable to the known 'antiwear' properties of phosphates so that they formed a boundary layer on the metal surface, which reduced the adhesive wear of the polyethylene counterface [20]. In serum, the phosphates may have interacted with proteins in the boundary lubrication.…”

Turbine Engine Lubricant and Additive Degradation Mechanisms

“…Rolling contact fatigue testing with M-50 bearings, for example indicated that PANA and DODPA added to a lubricant along with tricresyl phosphate resulted in an increase in wear over systems where the PANA and DODPA were absent [35]. An explanation might include the antioxidants reduce the oxidation of the metal surface which interferes with the binding of the phosphate ester to the surface [36]. Another system where results are unpredictable is when advanced bearing materials are used with polyolesters and phosphate esters.…”