Micro-abrasion-corrosion interactions of Ni-Cr/WC based coatings : approaches to construction of tribo-corrosion maps for the abrasion-corrosion synergism

The process of micro-abrasion-corrosion has been the subject of much research in recent years due to the fact that the action of micron sized particles, typically less than 10 um in diameter, can cause significant degradation of materials in many diverse environments involving aqueous corrosion. Cermet based coatings are often used to combat micro-abrasion-corrosion, but has been little work carried out to characterize the performance of such coatings exposed to micro-abrasion-corrosion or to provide a basis for coating optimisation. In addition, a basis for defining the various micro-abrasion-corrosion interactions has not been suggested to date. In this study the micro-abrasion-corrosion performance of a Ni-Cr/WC coating was assessed and compared to the performance of the steel substrate. The results were used to identify regimes of micro-abrasion as a function of applied load and pH of the solution. In addition, micro-abrasion-corrosion maps were constructed based on the results, showing the variation between micro-abrasion-corrosion regimes, as a function of applied load and pH of the solution

The Comstar D/3 gain degradation experiment

The results of gain degradation measurements using the Comstar D/3 19.04 GHz beacon are reported. This experiment utilized 0.6 and 5 m aperture antennas aligned along the same propagation path to examine propagation effects which are related to the antenna aperture size. Sample data for clear air, scintillation in clear air, and precipitation fading are presented. Distributions of the received signal levels and variances for both antennas are also presented

ATS-6 millimeter wavelength propagation experiment

The fixed 20/30 GHz ground terminal is described in detail; it is being used for path diversity measurements in the ATS-6 millimeter wavelength propagation experiment. The current status and summary of operations are reviewed

CTS/Comstar communications link characterization experiment

Measurements of angle of arrival and amplitude fluctuations on millimeter wavelength Earth-space communication links are described. Measurement of rainfall attenuation and radiometric temperature statistics and the assessment of the performance of a self-phased array as a receive antenna on an Earth-space link are also included