Oxidative Degradation of Phosphate Esters

Formation of lubricating films at elevated temperatures from the gas phase

“…It should be noted that deposit formation in the presence of air may involve a different mechanism than deposit formation in the presence of an inert gas such as nitrogen. This behavior has been observed in liquid phase TCP degradation where reaction in nitrogen gives rise to P-0-P bonding whereas, reaction in air causes aryl-to-aryl linkages with the formation of C-0-C bonds [15]. significant when the metal substrate has a strong catalytic effect.…”

“…The thermal stability of the alkyl phosphate (TBP) is generally not as good as that of triaryl phosphates, TCP and GT [15]. The four-ball wear tests on vapor-deposited lubricant films show no general correlation with either liquid-phase thermal or oxidative stabilities.…”

Exploring Failure Mechanisms of Lubricated 52100 Steel Contacts in High Vacuum and Dry Air

“…Under these conditions, equation (9) may be written as [2] T-Tb [l -t]A~)/ PPv]' (11)2 with N given by equation (10) and Tb by equation (8). This equation has the effect of bringing the bulk temperature and flash temperature close together at high pressures, while reducing to (9) at low pressure.…”

“…That is, the heat flow is evenly divided between the pin and the disk even though the pin experiences constant contact while the disk sees periodic contact. Equation (7) then simplifies to Tf -Tb + (uv (9) with Tb given by equation (8) and where N is the number of areas of real contact in the apparent contact area. This number is expressed as [2] N-F(l -F) + 1.…”

“…Oxidation of lubricants has been shown to form viscous films sometimes referred to as "friction polymer" [5][6][7][8][9][10][11]. Static oxidation tests of hydrocarbon lubricants [6][7][8][9][10][11] have given rise to products with molecular weights up to 50,000 on low carbon steel surfaces as opposed to 580 -860 for the original material.…”