The effect of the x-ray flux in x-ray photoelectron spectroscopy (XPS) on the constitution of the polytetrafluoroethylene (PTFE) surface has been examined. The radiation dose rate for our specimen was ∠107 rad/s. We observed the structure, magnitude and binding energy of the C(1s) and F(1s) features of the XPS spectrum and the mass spectrum of gaseous species evolved during irradiation. The strong time dependence of these signals over a period of several hours indicated that the surface constitution of PTFE is greatly affected by this level of radiation dose. The results are consistent with the development of a heavily cross-linked or branched structure in the PTFE surface region and the evolution of short chain fragments into the gas phase.

A pin-on-disk tribometer was used to study the coefficient of fiictio~z (1s (L filnction of temperature for tricresylphosphate (TCP) on C V M M -5 0 tool steel under the following conditions: T C P was present i n (L liquid reservoir (bulk lubrication), and T C P was applied cw. a liquid layer directly to the disk (limited lubrication). Under limited lubrication conditions, experiments were performed i n dry ( < 100 ppm H20) air, dry ( C 20 ppm H20) nitrogen, clry nitrogela zoith tlre disks heated to 700°C, then cooled to room temperu1~1,rc before the T C P was applied and the measurements made (/)reheated disks), and moist nitrogen using preheated disks. The coefficient of friction decreased at a characleristic temperature, T,.'I',. values obse~ved were: 265OC for bulk lubrication conditions i n dly air, 225OC for limited lubrication conditions i n dry air, and 215°C for limited lzibrication conditions i n dry nitrogen. The w e of preheated disks produced a sharp failure temperature at 2 1 8°C rohich was taken as the temperature about which the behavior of T C P should be judged. X-ray photoelectron spectroscopy confirmed tlre presence of phosphate on the surface of TCP-lubricated iron pins. Depth profile studies support the suggestion that a chemical reaction occurs between the T C P and the metal surjkce at T,.

State-of-the-art manufacturing of semiconductor devices involves the electrodeposition of copper for on-chip wiring of integrated circuits.

Radio frequency sputtering was used to deposit refractory carbide, silicide, and boride coatings on 440-C steel substrates. Both sputter etched and pre-oxidized substrates were used and the films were deposited with and without a substrate bias. The composition of the coatings was determined as a function of depth by x-ray photoelectron spectroscopy combined with argon ion etching. Friction and wear tests were conducted to evaluate coating adherence. In the interfacial region there was evidence that bias may produce a graded interface for some compounds. Biasing, while generally improving bulk film stoichiometry, can adversely affect adherence by removing interfacial oxide layers. in all cases but the iron oxide coverage was only complete on the preoxidized substrates. The film and iron oxides were mixed in the MoSi2 and Mo2C films but layered in the Mo2B5 films. In the case of mixed oxides, pre-oxidation enhanced film adherence. In the layered case it did not.