William H. Lucke

Applications of ion implantation for the improvement of localized corrosion resistance of M50 bearing steel

Abstract Pitting corrosion of M50 alloy steel bearings used in turbojet engines has been found to be a severe problem. The difficulty arises when salt-spray condensates accumulate in the engine lubricants of aircraft not in regular use. Ion implantation was applied to this problem because in the early stages of this work it was shown to be able to maintain both the dimensional stability and the contact fatigue lifetime of the M50 bearings. Qualitative tests, which simulated the geometry and thermal cycle conditions leading to pitting of the M50 bearing surface, were performed using oil containing 3 ppm NaCl. Initially it was found that chromium surface alloys containing 20–25% chromium substantially reduce the level of attack. Prior to further corrosion simulation tests, potentio-kinetic studies were carried out on M50 implanted with chromium, molybdenum and titanium in order to screen both the passivating tendency of the surface alloys formed and their resistance to localized forms of corrosion. Singular additions of chromium, molybdenum and titanium were found to increase the resistance of M50 to localized breakdown significantly. The highest resistance to localized breakdown was found for a multi-implantation of chromium and molybdenum.

Depth profiles of aluminum and sodium near surfaces: Nuclear resonance method

Depth profiles of aluminum and sodium implanted into silicon carbide, silicon and silicon dioxide have been measured by means of sharp resonances in the reactions 27Al(p,γ)28Si and 23Na(p,γ)24Mg. The absolute number of impurity atoms has been determined and compared with that indicated by charge integration during implantation. Adjacent areas of some specimens have been measured by the Cameca ion-beam mass spectrometer and the nuclear resonance method; results are compared. A depth resolution of less than 20 A has been demonstrated for Al very near the surface of SiC. Information concerning the migration of sodium in SiO2 under ion bombardment is presented. Depth profiles are extracted from gamma-ray yield curves taking into account the beam energy distribution, the resonance shape, the average proton energy loss in the sample and the energy loss straggling.

Optical and electrical properties of boron‐implanted amorphous germanium thin films

Amorphous germanium films were implanted to high boron levels, ∼1021/cm3 peak concentrations. Before and after implantation the conductivity measurements fit the relation logσ∼T−1/4 and no evidence of intravalence absorption was observed indicating that the Fermi level was near the center of the band gap. Thermoelectric power measurements indicated that the samples were weakly n type before implantation and p type after implantation. The position of the fundamental absorption edge shifted to lower energy upon implantation and to higher energies upon subsequent anneals. Implanted recrystallized films were strongly p type, exhibited intravalence absorption, and had very low dc activation energies.

Effects of annealing on profiles of aluminum implanted in silicon carbide

The effects of isothermal annealing on the profiles of heavy (4×1016 Al+/cm2 at 60 keV) implantations of Al in SiC were investigated by means of the 27Al(p,γ)28Si nuclear resonance technique. Annealing at 1400 °C for 15 min resulted in the apparent outdiffusion of about 30% of the implanted Al, an accumulation of Al at the surface, and a residual peak at the depth of the as−implanted profile. Subsequent annealing showed continued apparent outdiffusion with the release of Al from trapping sites as the rate−limiting process.

Phosphor preparation by ion implantation

Abstract 6H silicon carbide crystals have been subjected to 11B+ ion implantation and subsequent annealing and found to show the yellow boron photoluminescence.

Application of an Extension of Linde's Rule to Some Dilute Alloys of Cu, Mg, and Al

It is proposed that Lindes rule be extended by including a term linear in the valence difference between solute and solvent. Justification based on the Born approximation and experiment is adduced.