Conduction currents in Mylar and Teflon films were measured at applied field strengths of 2–1400 kV·cm−1 and at a number of temperatures in the range 70°–163°C. The samples were carefully conditioned.
The current varied with voltage as exp (αV01/2), and its temperature behavior was consistent with an activation process, giving an activation energy for conduction essentially independent of sample thickness, except at low fields. This change in activation energy with thickness at low fields, along with breaks in the Schottky plots are attributed to space-charge effects. The data did not fit a hyperbolic sine relationship previously applied to this system in support of an ionic mechanism. The results are discussed in terms of available theories of conduction in solids.
A large number of combinations of materials, both metallic and nonmetallic, were subjected to conditions producing fretting corrosion in an effort to evaluate their comparative susceptibility to this action. A table is given listing the results in three groups of relative resistance. Observations were also made to determine qualitatively the effect of such variables as velocity of slip, pressure between surfaces, amount of slip, and surface finish. All rigid materials were found either to corrode with oxide debris or to be affected by a fretting action which roughened the surface. Two contradictions to published data were found in that magnesium on cast iron is a poor combination and that surface roughness has little effect. Some nonmetallic materials are worse than metals. Dry lubricants delay the action, whereas rubber cement by excluding air prevented corrosion during the test life. A rubber gasket completely stopped the corrosive action.
To determine the effect of hardness onfretting wear, tests of AfSf 4340 steel were made in an oil bath using a new machine designed to make fretting corrosion tests with a wide range of parameters. Hardness values from 258 to 743 Vickers were tested, the hardest specimen having a nitrided surface. The fretting action used, 0.005 in. reciprocating motion at pressuresfrom 430 psi to 5840 psi, produced much lessfretting than similar tests in air, with little or no.oxide products resulting. The galled areas were measuredfor depth of pit and height of deposit with the results indicating some small effects due to hardness up to 460 Vickers. The nitrided specimens, however, produced smaller fretted areas and the roughening of their surfaces was shallow.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.