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This article deals with analysis of the influence of certain factors on polyethylene oxidative wear. The preliminary oxidation, arising during the technological processing, is considered along with the direct oxidation, occurring during friction under the influence of atmospheric oxygen and metal oxides, which are to be found on the sliding surface of the metallic counterbody.
The interaction between a growing surface oxide and impacting particles is of importance in many high temperature applications such as gas turbines and combined cycle power generation systems and may often result in accelerated rates of metal wastage. In this paper the interaction between a growing oxide film and an impacting particle is considered. The impact conditions are analysed to predict the...
The wastage behaviour of four low alloy steels, suitable for use as evaporator tubing in industrial atmospheric fluidized bed combustors (AFBCs), was examined in a laboratory-scale test rig. Specimens exposed in the test apparatus experienced a high flux of impacts at low particle velocities similar to conditions in a FBC boiler. The influence of time, velocity and temperature on the wastage behaviour...
The erosion-corrosion behavior of Ti-6A1-4V exposed to air environment up to 800 o C has been studied. Erosion experiments were performed in a sand-blast type of test rig at seven different temperatures. The specimens were heat treated by annealing and solution treating and aging. The target specimens were eroded with 120 grit silicon carbide particles at impact velocities from 55 to 110 m...
A whirling-arm erosion-corrosion rig has been designed and constructed to allow studies under gaseous conditions of high-sulphur, low-oxygen activities at high temperatures; these environments are pertinent in processes such as gasification of coal and catalytic cracking of oil. The system can operate at particle impact velocities up to 30 m s -1 , particle impact fluxes up to 1 g cm...
In order to simulate the wear of the valves and valve seat inserts of automotive engines, impact wear tests were conducted using rings made of a JIS SUH36 steel valve material and disks made of a sintered alloy valve seat insert material. Test conditions were as follows: impact energy of 0.588 J, dry air of room temperature, 200°C and 400°C, and sliding speeds of 0-0.8 m s -1 . Under...
This paper describes an experimental study on the temperature-dependent tribological behavior and oxidation of a carbon-carbon (C/C) composite material sliding against itself in ambient air up to 1800°C. Tribological experiments were conducted with a ring-on-ring type of apparatus using a wide range of load and speed conditions. As the specimen temperature gradually increased with frictional heating,...
Both the structural changes and frictional properties of CrN films, on two different substrate materials, were investigated as a function of both the effects of operating conditions and the effects of oxidization. The tribological behaviour reflecting these two kinds of effects is expressed by the tribological parameters of wear loss, the friction coefficient and the wear mechanism. The formation...
The crossing of the electric current in rail lines through a copper/steel sliding contact is associated with an electric field between the sliding surfaces. The electric field increases with the current intensity, the sliding speed and the contact resistance, and it decreases with an applied normal load. An electric field enhances the oxidation of surfaces, and the growth of such an oxide layer increases...
The dependence of friction coefficient vs. temperature of Hastelloy C/CeF 3 compact was studied in the paper. The wear debris was studied by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Findings indicated that CeF 3 had physical and chemical effects in sliding at evaluated temperatures. The physical effects were known as preferential orientation, degree of...
In the paper, the tribological characteristics of CeF 3 compact sliding against high speed steel and stainless steel were studied. The sliding oxidation behavior of CeF 3 compact was investigated and compared with that of in sliding against Hastelloy C, a Ni-based alloy. Findings indicated that the sliding oxidation behavior was different as a result of different materials of the pin...
In previous work, sliding abrasion by interfacial flint particles was studied for a nickel-base MMC under argon up to 900 o C. In the present investigation flint is replaced by corundum and silicon carbide. The hot hardness of the latter is above that of the NiCrAlSi-matrix and the WC/W 2 C particles, which dramatically lowers the wear resistance of the MMC compared to abrasion by...
The effect of post-irradiation shelf-aging time on the wear of orthopaedic grade UHMWPE was investigated, and wear results were correlated with the time-dependent microstructural changes of polyethylene after gamma irradiation sterilization. The levels of oxidation, crosslinking, and crystallinity in the shelf-aged acetabular liners were examined by FTIR, hot xylene extraction, and DSC, respectively...
Samples from a couple of work rolls employed in a hot rolling steel strip mill were examined by scanning electron microscopy in order to study their surface, as well as the wear mechanisms responsible for their damage. It was found that a series of cracks develop within the rolls at the beginning of their operational cycle, these cracks follow the primary carbide network and are attributed to be caused...
The wear behaviour of thermal oxidation (TO)-treated as well as untreated Ti6Al4V alloy has been investigated using an Amsler tribometer in rolling-sliding motion under boundary lubrication conditions. The results show that the TO treatment can significantly enhance the wear resistance of Ti6Al4V alloy. Based on the experimental results, in conjunction with systematic analyses, the wear-reduction...
This study concerns the behaviour of plasma and flame sprayed modified nickel-chromium alloy (with small aluminium and titanium additions) subjected to the action of simulated post-combustion gases from a coal-fired boiler combustor. The study first evaluates the effects of thermal exposure at high temperature on the adherence between the substrate (austenitic stainless steel) and coatings. Then,...
The concept of active wear track area is proposed as a way to investigate the mechanism of the corrosion-wear behavior of passive materials under sliding conditions. This active wear track area represents that part of the wear track that looses temporarily its passive character due to the mechanical interaction during sliding. It is shown that the active wear track area can be determined from repassivation...
In hot forming processes, the interface tool/product is important for the quality of the finished product. In hot rolling, the scale formed on the roll material plays an essential role. As soon as the contact oxide–oxide is established between the roll and the slab, friction allows the process to start. However, the oxide scale will continue to grow under the cyclic action of hot contacts and water...
We have studied the tribological behavior of a XC 48 steel/XC 48 steel sliding couple in the presence of an A.C. magnetic field. Experiments were conducted on a pin-on-disc tribometer in ambient atmosphere under an applied normal load P=62.85N and sliding speed v=0.38m/s. The magnetic field was applied to the pin and remained constant during each test. Experimental results showed that the presence...
High temperature wear characteristics of Stellite 6 alloy containing Cr 3 C 2 after thermal fatigue and oxidation treatment at 700°C were investigated. The hardfacing layer was deposited by plasma transferred arc (PTA) process. After thermal fatigue treatment, cracks propagated along boundaries of incoherent chromium carbide particles. Significant oxidation occurred mainly on the clad...
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