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Firing tests of a small caliber experimental gun barrel made of a cobalt-base alloy have been conducted with the purpose of determining the degree of wear and erosion due to excessive firing durations. The small amount of barrel material loss makes the cobalt-base alloy an excellent candidate for use as a gun liner. An unusual wear pattern resulting from this loss was observed near the muzzle. Elimination...
The characteristics of wear debris particles are valuable information sources for machine condition monitoring. A possible approach is to apply ferrography with computer vision techniques. However, when images are captured on-line, it is observed that particles tend to appear agglomerated and an effective image processing method is hence required. A particle extraction procedure is here developed...
Four epoxy-based multilayer coating systems, with thicknesses of 380±20μm, 650±10μm, 720±30μm and 920±20μm, were applied manually onto stainless steel samples and subjected to vibratory cavitation tests according to ASTM G32-09 standard. In order to correlate the cavitation resistance of the coating systems with some of their mechanical properties, instrumented micro indentation tests were performed...
Effect of 25keV proton irradiation with fluence of 2.25×10 17 ion/cm 2 on the structural and tribological properties of polyimide blocks were investigated in a ground-based simulation facility. The changes in surface structure were characterized by FTIR-ATR, laser micro-Raman, contact angle measurement and nanoindentation. The experimental results indicated that the proton irradiation...
Increased traffic and intensified operating conditions cause more and more damage on rails manifesting themselves in rolling contact fatigue cracks and wear. Rolling contact fatigue, e.g. head checking, is classified safety critical as these cracks may lead to the derailment of a vehicle. For that reason research and development is mainly focused on designing novel, more damage resistant rail steels...
This work concerns the review of fretting-simulation models developed at the Technical University of Berlin (TUB). The presented concept aims to predict the fatigue strength of assemblies subject to fretting corrosion. For such problems it is assumed that a local fatigue strength calculation has to take into account the redistribution of loads due to wear and hence has to be applied to the worn surface...
A new high-speed test rig was designed to simulate the interactions between labyrinth seals and abradable coatings in similar turbo-engine operating conditions. To determine a solution for turbo-engine efficiency enhancement, we investigated the clearance reduction between the rotary parts in air systems, the successive starts and stops, the thermal expansion and the vibrations that might cause direct...
Numerical models of surface micro-topography find applications in the development of multiscale models for friction and wear between two interacting surfaces. Although much work has been dedicated to developing such multiscale models, they have been hampered by the strong dependence of surface statistics on the resolution of surface topography measurements. The objective of this study is to develop...
Mechanical properties and wear behavior of stainless steel supplemented with different solid lubricants were investigated. Hexagonal boron nitride (h-BN), molybdenum disulfide (MoS 2 ), and a mixture of h-BN/MoS 2 embedded in 316L stainless steels (SS316L/h-BN, SS316L/MoS 2 and SS316L/h-BN/MoS 2 ) were prepared by powder metallurgy method. Various solid lubricant contents...
Load bearing implant prostheses such as orthopaedic hip and knee implants may be considered as tribocorrosion systems since the wear processes are a result of combined mechanical and chemical mechanisms. The long-term success of implant prostheses depends on a number of factors, including age, body weight and activity levels. Pre-clinical testing is therefore crucial in determining the long-term performance,...
The local deformation induced by vibratory cavitation erosion in a CuSnNi alloy was studied employing electron back-scattering diffraction and three-dimensional profiling. The study focused on evaluating initial plastic deformation corresponding to a group of 57 grains in order to correlate crystal orientation and local deformation morphologies. While detectable slip markings developed in grains oriented...
The abrasive wear of carbide-free bainitic steel under dry rolling/sliding conditions has been studied. It is demonstrated that this nanostructure, generated by isothermal transformation at 200°C, has a resistance to wear that supersedes that of other carbide-free bainitic steels transformed at higher temperatures. The experimental results in combination with a theoretical analysis of rolling/sliding...
The exhaust plumes from spacecraft landing on Earth׳s moon advect lunar dust particles which have been shown to erode, or “sandblast”, nearby objects. Evidence of this phenomenon was provided by NASA’s Apollo 12 mission during which exhaust ejecta, generated by the Apollo Lunar Module landing, erosively wore components of the Surveyor III lunar probe located 155m from the Apollo 12 landing site. Recently,...
Solid lubricant materials have become necessary in applications for which traditional lubrication approaches become impractical. These materials are often mated against a harder metallic counter surface (counterface) of higher surface energy. During sliding, wear fragments from the solid lubricant transfer to the counterface to form a protective barrier known as the transfer film. Historically, the...
Understanding the detailed progression of cutting tool deterioration is important in order to improve the milling of Ni-based superalloys. Therefore, a series of documented experiments have been conducted on alloy 718Plus using cemented carbide (WC–Co) tools. It has been observed that the commonly recognised build up layer in the initial stage does not significantly affect the tool deterioration process...
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