Ted A. Morgan

A model of the dynamics of boundary film formation

Abstract The dynamics of formation and loss of the boundary films formed during sliding on steel surfaces were investigated over a range of temperature. Tests are performed on a cylinder-on-disk machine using mineral oil with various concentrations of zinc dialkyldithiophosphate (ZDP). The thickness and refractive index of the boundary films during step load test were monitored in situ with an ellipsometer, and the composition of the films was analyzed by X-ray photoelectron spectroscopy (XPS). As temperature increases, chemical reactivity increases the film formation rate, while the film removal rate increases owing to (a) the decrease of durability of the boundary film material and (b) the reduction of hydrodynamic fluid film thickness due to decreasing viscosity of the lubricant. There is a balance between these two competing mechanisms, and this balance is reflected in the boundary film thickness. The boundary films consist of a film of oxide and metallic compound (OMM) covered by an organo-iron compound (OIC). Their relative effectiveness in preventing scuffing depends on temperature and composition. In particular, the OIC is effective in reducing wear of the opposing surfaces by covering the OMM.

Development and tribological properties of new cyclotriphosphazene high temperature lubricants for aircraft gas turbine engines

A number of substituted aryloxycyclotriphosphazenes were synthesized and studied, with the objective of meeting the lubricant requirements of the Integrated High Performance Turbine Engine Technology (IHPTET) initiative. These compounds were evaluated for pour point, oxidative stability, and lubricity behavior. Further property evaluations were performed on a leading candidate fluid, bis(4-fluorophenoxy)-tetrakis(3-trifluoromethylphenoxy) cyclotriphosphazene, code-named X-1P. The results of this study are discussed, along with comparative data of other leading commercial high temperature fluids. Presented at the 46th Annual Meeting in Montreal, Quebec, Canada April 29–May 2, 1991

A model for the boundary film formation and tribological behavior of a phosphazene lubricant on steel

The dynamics of formation and loss of the boundary films formed during the lubricated sliding of steel surfaces were investigated over a range of temperature and applied load. Tests were performed on a cyldinder-on-disk machine using a phosphazene lubricant (X-1P), a polyphenyl ether, and mineral oil with and without addition of zinc dialkyldithiophosphate (ZDP). Among these lubricants, X-1P was found to have the best high-temperature, high-load performance. The thickness and retractive index of the boundary films were monitored in situ with an ellipsometer, and the composition of the films was analyzed by X-ray photoelectron spectroscopy (XPS). The performance of the lubricants was found to be closely associated with boundary film-forming ability. In order to achieve high load-carrying capacity, a boundary film must be formed. The films formed in X-1P grow more slowly than those in ZDP-containing mineral oil, but they remain thick even at high load and high temperature (250°C). These films are durable and effective in reducing friction and preventing scuffing. The film formed with X-1P consists of a mixture of compounds containing Fe, O, C, F, P, and N. Among the compounds formed, some form of iron fluoride appears to be most important in determining the performance of the film.

Cyclotriphosphazenes as Potential Lubricants for Thin Film Hard Disks

This paper explores the use of phosphazenes as alternative lubricants for thin film hard disks. Contact start/slop (CSS), stiction and drag tests were performed on five disks lubricated with a typical cyclic phosphazene lubricant, X-1p, with a thickness in the range of 0.3 nm to 0.7 nm. The coefficients of friction and stiction were found to increase initially, then level off and reach a steady-state value without a further increase after 2000 CSS cycles, ft is concluded that X-1p performs well on thin film disks with a lubricant thickness of about 0.5 nm. Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Lahaina, Hawaii, October 16–20, 1994

New class of brominated polymeric flame retardants for use in polystyrene foams

Flame retardant producers and end users are continually looking for more sustainable solutions through innovation in their customer offerings. Successful solutions need to satisfy a range of characteristics, from processing to technical and environmental performance, which sometimes conflict. This paper covers a new class of brominated polymeric flame retardants designed and developed by The Dow Chemical Company for use in polystyrene foam to meet existing fire and use requirements and have an improved environmental profile to meet regulatory guidelines. An overview of the environmental, health and safety performance of these new polymeric flame retardants will be presented along with preliminary performance data of their use in polystyrene foam.