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The major objective of the present work is to evaluate the influence of decarburization of the WC–12Co coatings and also the abrasive characteristics on its abrasive wear behavior using a planned set of dry sand rubber wheel abrasion tests. Towards this purpose, detonation sprayed coatings have been deposited at three levels of oxygen to fuel ratios so as to obtain WC–12Co coatings with decarburization...
Thermal localisation (TL) phenomenon is defined as localisation of high temperature as consequences of high strain gradients developed in the bulk of materials of a tribo-pair. High extent of localisation of thermal gradient is rated as a non-desirable parameter for a good friction material because it affects both the surfaces leading to thermal crazing, cracks and fatigue, especially of the disc...
Effect of two grades of carbon black (CB) on structure, strength and tribological behavior of PTFE-CB composites is studied in the filler range of 10mass%. It is found that differences in surface properties of the fillers used to determine the type of supermolecular structure evolved and patterns of variation of mechanical properties, friction and wear in response to increasing filler content.It is...
Polymer debris from the sliding wear of a rotating steel wheel on flat polyethylene was traced using the radioisotope indium-111 to identify wear debris pathways. The radioisotope was ion-implanted just below the surface of ultra-high molecular weight polyethylene samples at a mean implantation depth of 144nm. The implantation fluence was 4×10 12 ions/cm 2 or less. Several samples...
The current work is an attempt to use treated betelnut fibres (in mat form) as reinforcement in polyester composites. The fibres were obtained from Alor Star in the state of Kedah, Malaysia. Wear and frictional characteristics of T-BFRP composite were investigated against polished stainless steel counterface under dry/wet contact conditions using a BOD machine. The tests were conducted at 2.8m/s sliding...
Fretting corrosion is a complex phenomena and a variety of factors such as load, contact area, frequency, number of fretting cycles, extent of damage of the fretted zone, trapping of debris between the contacting surfaces, corrosivity of the medium, etc., will determine the fretting-corrosion behaviour. The present paper aims to develop a fretting-corrosion map of commercially pure Ti (CP-Ti) based...
In the present investigation, tribological characteristics of spray formed and hot pressed Al–6.5Si, Al–12.5Si and Al–12.5Si–25Sn alloys have been studied. The alloys were spray formed in an environmental chamber using nitrogen gas at 1.0MPa gas pressure and a deposition distance of 350mm. The preforms were vacuum hot pressed, at appropriate temperatures, to achieve its densification, The spray formed...
Friction and wear properties of WC–Co cemented carbides with Co concentrations ranging from 6 up to 12wt% and WC grain sizes in the sub-micrometer scale have been examined in reciprocating sliding wear experiments using a high-frequency TE77 pin-on-plate system. The aim of the work was to investigate the influence of test parameters such as normal contact force, oscillating velocity and sliding distance...
A sliding contact of a two-layered elastic foundation and a periodic system of dies (which is a rough body model) is considered. To study the process of contact fatigue fracture of the elastic layer, a calculation procedure is developed. The method includes the periodic contact problem solution, internal stress calculations taking into account sliding friction, and construction of the damage accumulation...
The normal impact of thermal barrier coatings by spherical particles is analysed by the finite element method in order to determine the transient stress state and potential for erosion. During the impact event, the deformation response can progress from elasto-dynamic to quasi-static elastic and then plastic. The precise sequence depends upon the size and velocity of the impacting particle, and upon...
Atomic force microscopy (AFM) and scanning probe microscopy (SPM) were used to study the surface topography of electrodeposited pure nickel with different grain sizes from ultra-fine to nanoscale level. Such technique, coupled with nanoindentation and nanoscratch experiments allowed to map the nano-tribomechanism acting on the same pure metal with different mechanical and topographical properties.
The wear resistance of Zn–Al alloys is determined in pin-on-ring wear tests, as a function of type of structure of the as-cast alloys. Three regions were observed; columnar, equiaxed and columnar-to-equiaxed grain transition. The results show that the equiaxed structure is the most resistant. In addition, the relation between wear rate and grain size depends on type of structure and it is more pronounced...
This paper directly examines the contact sliding distance experienced during a typical sheet metal stamping process—an area that has largely been neglected in the literature. A method to numerically quantify the sliding distance is proposed. The sliding distance predicted from this method, and the contact pressure obtained from numerical simulation, allow the recently identified time-dependent contact...
In the present study, the mechanisms and microstructures of surface seizure induced scuffing in oil lubrication were investigated using experimental data including the profile of scuffing cavities and their surrounding plateaus, the chemical elements generated at these cavities, the selected area diffraction pattern of the lower specimen's cross-section surface, and the energy dispersive spectrum...
In situ Al-based composites were fabricated by exothermic dispersion method. Dry sliding wear results showed that the original C/ZrO 2 mole ratio is a key factor to the wear behavior of the composites. When the ratio of C/ZrO 2 =0, the reinforcements are mainly composed of Al 3 Zr particles and α-Al 2 O 3 particles, and it is suggested that the dominant wear...
The light-weight approach and fuel economy targets in today's automotive engineering require tribosystems, which can withstand higher contact pressures associated with low coefficients of friction. The application of high-performance coatings represents one approach among others. This paper presents some recently developed DLC coatings (a-C:H and ta-C) as well as a novel coating-substrate system (Zr(C,N))...
This work presents an analysis of the transient creep deformation of a hemisphere in contact with a rigid flat, loaded by a constant force. The analysis is based on extensive finite element simulations, using a Garofalo creep law. Motivated by the simulations, an analytical framework is derived. Starting from the trivial case of a cylinder, the analytical framework can be generalized by exchanging...
A kind of steam impaction apparatus was developed to study the influence of microparticles on steam erosion. After 10min exposure, no erosion pits appeared on the mild carbon steel surface under the impaction of pure water steam when the steam speed was controlled below the threshold velocity. However, at the same speed, erosion pits appeared on the surface when SiC microparticles were added into...
Dental filling materials are subjected to cyclic compression in the mouth. Nine resin-based composite filling materials were subjected to 2000 compression cycles between either 0 and 12kg, or 0 and 40kg. Surface deformation was measured as the diameter of the compression scar and surface microhardness determined by a Vickers’ microhardness test at 4 sites around the scar. Subsurface damage was stained...
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