Increase In Wear Life Research Articles

The enhancement of wear life and moisture resistance of sputtered MoS 2 films by metal ion implantation

In the present paper, studies of the effects of metal ion (Y +, Ag +) implantation on the tribology and moisture resistance of r.f.-sputtered MoS 2 films are reported. The scratch test indicates an improved film-substrate adherence. This is mainly attributed to the mixing interface which was caused by metal ion implantation. The tribological test results indicate that metal ion implantation improves the wear life of the sputtered MoS 2 films in an atmosphere of 60–70% relative humidity (RH) by a factor of 2–3. However, it slightly increases the friction coefficient from 0.07 to 0.09. After being stored in an atmosphere of 100% RH for 120 h, Ag +-modified MoS 2 films showed an increase in wear life by a factor of 8 compared with that of as-deposited MoS 2 films stored under the same conditions. These results indicate that Ag implantation enhances the moisture resistance of the sputtered MoS 2 films. The relationship between the chemical changes of the sputtered MoS 2 films and their moisture resistance is also discussed.

Production of friction surfaced components using steel metal matrix composites produced by Osprey process

Steel matrix composites produced by the Osprey process have been hot worked to produce barstock for the friction surfacing process developed by Frictec. Examination of the friction surfaced components reveals that a complete transformation of the original composite microstructure has taken place, producing a high degree of ceramic particle refinement and redistribution in the steel matrix. Initial laboratory wear tests indicate a significant increase in wear life. Applications and future developments are discussed.

Structure and composition of ZrN and (Ti,Al)N coatings

Triode ion plated ZrN and (Ti,Al)N thin films were deposited on high-speed steel and stainless-steel substrates. The samples studied in this work were selected on the basis of their cutting performance in turning tests as reported earlier. In cutting tests (Ti,Al)N and ZrN both showed significantly increased wear life as compared to standard TiN. X-ray diffraction studies revealed for (Ti,Al)N a cubic B-1 NaCl structure with strong (200) orientation. The initial morphology was columnar, but by increasing the substrate current density the columnar growth could be suppressed and a finer structure resulted, while wear life in turning also increased. All ZrN coatings showed B-1 NaCl structure with a (111) preferred orientation. Their fracture surface was always noncolumnar and almost featureless as judged by scanning electron microscopy. However, cross-sectional transmission electron microscopy studies revealed a fine columnar structure also with these films. The ZrN coatings had a uniform through-thickness nuclear resonance broadening nitrogen depth profile, whereas irregularities were observed in the (Ti, Al)N coatings and an uneven aluminum distribution was revealed also by backscattering measurements.

Reduction of Heat Transfer to High Velocity Gun Barrels by Wear-Reducing Additives

In order to understand how wear-reducing additives such as TiO2/wax and polyurethane foam liners reduce erosion, a series of gun firings was made in a 105 mm tank cannon equipped with thermocouples to measure the heat transferred to the gun barrel both in the presence and in the absence of the additives. Four thin thermocouples (0.13 mm diameter) were placed at different radial distances from the bore surface. Each thermocouple was placed at the same axial distance along the gun barrel. From the temperature distribution measured 100 milliseconds after propellant ignition, the total heat transferred in the gun barrel was determined. On the basis of single shot measurements, both the polyurethane foam and the TiO2/wax liner reduced the heat transferred to the gun barrel by ten percent. Repeated firings with TiO2/wax liners afforded steadily increasing reduction in heat transfer which was attributed to the formation of an insulating layer of TiO2 and unreacted wax on the bore surface. This also accounts for the twenty-five fold increase in wear life of the M68 tank cannon firing rounds equipped with TiO2/wax liners. This thermocouple technique is now used to design optimum weight and location of wear-reducing additives in other gun systems, since the efficacy of the wear-reducing liner can be deduced from a few shots.