The development of PVD coatings on pistons for internal combustion engines is described. The aim is to achieve better control of friction, wear, oxidation and corrosion in critical engine components such as pistons and cylinders in order to achieve higher energy efficiency, prolonged life and improved power output. The aim of the study was to find an optimum substrate-coating combination for aluminium piston applications. PVD CrN arc deposited coatings have been found to offer excellent properties for this application, showing improved friction and wear properties and good adhesion as measured in the scratch test. The coating process has been shown not to affect the hardness or microstructure of the LM-13 piston alloy.
Extrinsic surface states for oxygen chemisorbed on the GaAs (110) surface J. Vac. Sci. Technol. 15, 1287 (1978; 10.1116/1.569754 Surface structure and orbital symmetries of (110) surface states of GaAs Native surface defects on gallium arsenide are detected by thermally stimulated exoelectron emission measurements. Two emission peaks were identified that were correlated to the AsGa antisite defect. Plasma polymerized polythiophene grown on cleaned gallium arsenide is shown to improve the photoluminescence intensity of gallium arsenide and consequently the exoelectron emission measurements indicated the disappearance~of one of the peaks. The results thus confirm the passivation of one of the AsGa antisite defects. The effects are also discussed in view of the low angle x-ray diffraction spectrum for cleaned and polythiophene treated gallium arsenide. Growth of species involving gallium sulfur and arsenic, sulfur were also detected. 155
Vacuum-evaporated thin films of polyphenylene sulphide have been used as an insulating overlayer on n-GaAs(110). Sulphur present in the polymer is seen to passivate the dangling bonds of GaAs. The interface of n-GaAs/polyphenylene sulphide was studied using grazing-angle x-ray diffraction at various angles for different annealing temperatures. The electronic properties of the interface are studied using electron-beam-induced-current measurements for determining the minority-carrier diffusion length and surface recombination velocity. The x-ray-diffraction analysis indicates the formation of arsenic sulphide at the interface and is expected to reduce the dangling bond density. The treated surface shows an increase in diffusion length and reduction in the surface recombination velocity. The polymer-semiconductor interface shows stability against annealing up to a temperature of 300 °C.
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