Implantation of Ti and C into stainless steel discs of Types 304, 15–5 PH, Nitronic 60 and 440C has previously been reported to reduce wear depths by up to ∼ 85% and friction by ∼ 50% in unlubricated pin-on-disc tests. Our earlier studies relating microstructure to friction and wear results in Type 304 are first summarized; these indicate that the improvements in the surface mechanical properties are due to an amorphous surface layer, similar to the amorphous layer observed in pure Fe implanted with Ti and C. We have now examined the other three implanted steels and found similar amorphous layers. These results strongly suggest that the amorphous surface alloy is responsible for reduced friction and wear in all the steels.

Friction and wear tests on ion-implanted 440C stainless steel discs have been extended to high Hertzian stresses (≤ 3150 MPa). Implantation of 2 × 1015 Ti/mm2 (180–90 keV) and 2 × 1015 C/mm2 (30 keV) into 440C reduces friction (∼40%) and wear (> 80%) for Hertzian stresses as large as 2900 MPa, stresses which significantly exceed the yield strength of 440C (∼1840 MPa). Implantation of 4 × 1015 N/mm2 (50 keV) into 440C reduces friction slightly (∼25%) for Hertzian stresses > 1840 MPa but provides little or no reduction in wear. The amount of Ti remaining in the wear tracks correlates with the reductions in friction and wear. The implantation of Ti and C produces an amorphous surface layer which is believed to reduce friction and wear, whereas N implantation is expected to produce hard nitride particles which probably do not modify the hardness of 440C (KHN = 789) significantly.

Friction and wear measurements were performed with a hardened steel ball sliding against unhardened steels (AISI 10184 304 and M2) implanted with either N+ or Ti+ or both N+ Ti+ ions. Dry and lubricated sliding studies found that: Ti-implantation reduced friction and thereby delayed wear; N-implantation did not reduce friction but delayed wear by increasing the resistance of the surface to shear; and dual implants of N+ + Ti+ showed effects of both implants. Auger sputter depth profiles found the 1018 and M2 surfaces enriched in implanted N and bulk C. No evidence of N migration could be found in heavily deformed surfaces.

Titanium implantation into steels has been shown to produce superior tribological surfaces. The fluence required to produce a wear resistant surface increases from 2 to 5×1017 Ti/cm2 as the energy increases from 50 to 200 keV/ion. On curved surfaces (e.g., bearings, cutting tools, etc.) higher fluences are necessary due to effects of implantation at angles off normal incidence (i.e. the combined effects of higher sputtering rates, decreased range, and changes in the carburization process associated with duty cycles). Significant improvements in friction and wear have also been observed for surfaces which have been abraded by 600 and 120 grit SiC prior to implantation. Optimal benefits of Ti-implantation are associated with the formation of a modestly thick (>20nm) fully carburized layer.

Block-on-ring wear tests were performed on Ti-implanted AISI 52100 steel sliding against three commercial alloys: CDA 673 brass, AISI 4140 low alloy steel, and AISI 0–6 tool steel. A turbine oil, meeting MIL-L 23699 specifications, was used as the lubricant. The 52100 wear rings were ion implanted to a fluence of 2 × 1017 Ti/cm2 at 55 KeV or 125 KeV. Comparison with non-treated 52100 wear rings indicated that ion implantation reduced the amount of wear and wear variability. It is hypothesized that reduced adhesion and improved lubricant film formation due to the presence of the implanted layer was responsible for the reduction in wear and wear variability.

Cylindrical 440C stainless steel specimens implanted with N and Ti were examined for their fatigue resistance and wear behavior by rolling contact fatigue (RCF) testing. The results obtained from RCF testing showed a 40% increase in the B-10 fatigue lifetime for N implanted and a 17% increase for Ti implanted 440C specimens compared to baseline, unimplanted 440C. Quantitative surface analysis by Auger Electron Spectroscopy (AES) was performed to determine the effects of process parameter optimization and ion beam masking on the elemental concentration profiles.

Clarification of the relationship between nitrogen profiles and wear behaviour has been sought by studying nitrogen implanted mild steel. Implant energy and dose were in the ranges 25 – 65 keV and 0.9 − 3 × 1017 1ions cm−2, respectively. Wear characteristics were measured with a ball-on-disc system followed by interferometric analysis. Nitrogen distributions before and after wear were determined by Auger electron spectroscopy and Rutherford backscattering methods, and compared with wear track profiles. On balance, the data offers qualified support for nitrogen migration at low loads, although nitrogen was not detected for wear depths >2 times the implant depth. Observations of wear on the abrader ball-bearing surface and the role of oxygen in the wear process are reported.

The friction and wear of Ti-6Al-4V are found to be sharply reduced by carbon implantation followed by heat treatment. Optimum wear resistance is developed at 400° C, at which the microstructure of the implanted layer shows a dense array of TiC precipitates up to 60 nm in size. The implanted layer in this case is worn through in a few thousand cycles of the ball on disc test, but by implanting at two energies to achieve a deeper carbide layer, negligible wear was found even after 20,000 cycles. No wear improvement was found for nitrogen implantation.

Titanium and many of its alloys show very poor wear resistance considering their hardness. This together with high thermodynamic driving forces to form very hard compounds between titanium and nitrogen or carbon made titanium based alloys obvious candidates for ion implantation. In this paper the effects of similar implanted concentration profiles of nitrogen and carbon in two titanium alloys are compared. The wear behavior of pin on disk wear tests are reported along with the ultramicrohardness of the four samples.

Mechanically polished Ti6Al4V samples were implanted with 100 key nitrogen ions to a fluence of 5.1017 ions/cm2 at two different bulk tenneratures: 370°C and 470°C. Wear tests were carried out with a reciprocating slidina tribotester. Structural modifications and wear morphologies were studied by TEM and SEM. 370°C implanted sample showed the same wear behavior as unimplanted ones, while 470°C implanted sample showed better wear resistance because of a TiN hardened layer. Correlations- between microstructural modifications, wear behavior and mechanisms are reported: results agree with the delamination theory. Comparison with ion- and gas-nitrided samples are presented.

Ion beam techniques have found increasing application in recent years to a wide variety of disciplines. It is the purpose of this paper to explore their potential in the field of catalysis, concentrating exclusively on solid heterogeneous catalysts. An initial description of the internal structure and external physical form of some typical catalysts is followed by an assessment of the use of ion beams for the preparation and interrogation of both “real” and model catalysts. These techniques are then compared to some of the modern tools used in current catalysis research. It emerges that ion beams can indeed be used to advantage in certain applications, such as detecting light elements selectively; measuring interaction effects between metals and supports in model systems; highlighting surface relaxation effects in metal single crystals; and even, in special circumstances, in synthesising catalysts.

Corrosion behavior of Ni+ -irradiated NiTi alloys was studied in chloride solutions, together with unirradiated NiTi material with different surface conditions. Ion irradiation with either 2.5 or 5 MeV Ni+ ions transformed the NiTi surface into an amorphous layer up to 1.5 micrometers thick. Studies of corrosion potential vs. time and polarization behavior indicated a small enhancement of the passivation for the Ni+-irradiated NiTi over the unirradiated NiTi. The unirradiated NiTi with a mechanically polished, coarse surface was susceptible to pitting and crevice corrosion attack in 1 N HCl solution. The homogeneous amorphous structure in the irradiated alloy retarded this type of localized corrosion.

The effects of N-ion implantation on the corrosive-wear properties of Ti-6Al-4V, an alloy used for construction of the femoral component of artificial hip joints in humans, were tested. In corrosive-wear tests designed to simulate pertinent hip-joint parameters, electrochemical corrosion currents were measured for cylindrical samples in saline electrolyte in an arrangement which allowed the samples to be rotated between loaded polyethylene pads simultaneously with the current measurement. To further quantify material removal, Zr markers were ion-implanted into some samples so that, by use of Rutherford backscattering, material removal could be detected by changes in position of the marker relative to the surface. Corrosion currents were greatly reduced by implantation of approximately 20 at. % N, but even implantation of the Zr markers also reduced corrosion currents. The marker experiments confirmed the low rate of material removal for the implanted samples.

Cr+ implantation of Ta was undertaken in an attempt to improve oxidation resistance at temperatures between 500 and 750°C, and for oxidation times up to l00h. Samples were implanted with 1.5×1017 Cr+/cm2 at 150 keV, and compared to samples implanted with 1×l016 or 1×1017 Ta+/cm2 at 145 keV to evaluate the role of physical effects from ion implantation. Following oxidation, samples were examined using helium and proton backscattering, electron and optical imaging techniques, and auger electron spectroscopy. Improved resistance to oxidation was observed in Cr+-implanted samples oxidized at 500°C for up to l00h, and at 600°C for about lh. However, some local breakdown occurred in these samples and no protection at all was observed at 750°C. Reasons for this breakdown are discussed and alternate approaches for improving oxidation resistance using ion implantation are proposed.

Initial studies of the oxidation resistance imparted to uranium metal through the implantation of Mo ions have shown that a significantly increased resistance can be achievedfor doses of 5 ×1016/cm2. No enhancement of oxidation resistance was found for doses below 1 ×1016/cm2. We report results of weight-gain measurements, ion-beam analysis, and x-ray diffraction, as well as observations of the way in which the protective implanted layer fails at long exposure times.

The hydriding of depleted uranium at 76 Torr hydrogen and 130°C has been significantly reduced by implantation of oxygen ions. The high-dose implanted specimens had incubation times for the initiation of the reaction after exposure to hydrogen that exceeded those of the non-implanted specimens by more than a factor of eight. Furthermore, the nonimplanted specimens consumed enough hydrogen to cause macroscopic flaking of essentially the entire surface in times much less than the incubation time for the high-dose implanted specimens. In contrast, the ion-implanted specimens reacted only at isolated spots with the major fraction of the surface area unaffected by the hydrogen exposure.

Materials presently used for packaging precision instrument bearings contain minor amounts of antistatic agents, shown earlier to be potential contaminants to both bearing surfaces and lubricants. One method to eliminate the antistatic additives is to use electroactive polymers. The materials with the most promise for this application are the F ion implanted polyacetylene and polyparaphenylene. The characteristics and behavior of the polymers will be presented.

Indium-Tin Oxide (ITO) heat mirror films implanted into window glass were obtained by post annealing of argon irradiated coatings of In-5w/o Sn produced by reactive evaporation in oxygen. Characterization of coatings has been carried out using TEM and AES. Optical properties have also been evaluated. The production of acceptable thin films requires low energy deposition rates during ion bombardment. This places a limit on the extent of film-substrate mixing, which is required if increased film lifetimes are to be realized.

The ion beam mixing technique has been employed to mix metal atoms into the surface layers of Al2O3. Ion beams of Fe+ and Zr+ in the 1 to 4 MeV energy range were used to irradiate Al2O3 specimens on the surfaces of which films of chromium or zirconium had been evaporated. Some specimens were irradiated at elevated temperatures of 873 or 1173 K. Rutherford backscattering (RBS) and channeling methods were used to measure the metal atom depth profiles near the surface. Analyses of the backscattering data included binary collision calculations using the codes TRIM and MARLOWE. The significance and limitations of high energy (>1 MeV) beams for ion beam mixing experiments is discussed. Evidence was found for radiation enhanced diffusion and/or solubility of zirconium and chromium in Al2O3 at 873 K.