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Some mechanical components of PWR nuclear power plants can be sensitive to wear damage resulting from contacts with their supports or guides due to flow-induced vibrations. It is particularly the case of the control rods (rod cluster control assemblies (RCCAs)) and RCC guide tubes inside the reactor pressure vessel. In order to improve our knowledge about the wear behavior of such components, an extensive...
The evolution of microstructures in the glazed layer formed during high temperature sliding wear of Nimonic 80A against Stellite 6 at 750 o C using a speed of 0.314ms -1 under a load of 7N has been investigated using scanning electron microscopy (SEM), energy dispersive analysis by X-ray (EDX), X-ray diffraction (XRD) analysis, scanning tunnelling microscopy (STM) and transmission...
The effect of oxide formation on the tribological properties of a CO 2 -laser processed Co-based material (Stellite 21) was investigated under high-load sliding conditions in air and in an oxygen free environment. The tests were carried out by sliding two identical specimens against each other in a load-scanning test. A friction coefficient at a level of about 0.20 was observed for both test...
In this work, the interfacial friction is investigated during a material removal test. Based on specially programmed experiments conducted on 6061 Al at 24 different conditions, it was found that the friction coefficient significantly varies in different temperature ranges. Using optical and transition electron microscopy, these variations were found to be dependent on phase changes within the workpiece...
The tribological behavior of Mo 5 Si 3 particle reinforced silicon nitride composites has been investigated by pin-on-disk wear testing under dry conditions. The friction coefficient of the Si 3 N 4 decreased with the incorporation of submicrometer-sized Mo 5 Si 3 particles and also as the content of Mo 5 Si 3 particles increased. The...
A great deal of research has been conducted to clarify the role of oxide films in the wear of metals. Oxides formed during dry sliding of steels at high temperatures determine their tribological behavior. The present work deals with the influence of the oxide-forming alloying elements aluminum and silicon on the oxidation and wear of three selected hot work steels. For this investigation, ball-on-disc...
In this investigation, Ti–45Al–2Nb–2Mn–1B (at%) titanium aluminide was thermally oxidised at different temperatures of 700–950°C and at different times. Most oxidation exposures resulted in the formation of a compound layer consisting of several oxide layers, a TiO 2 layer as the outermost layer on top of a layer of Al 2 O 3 particles, a mixed layer of TiO 2 +Al ...
The frictional behavior of aluminum was studied with a pin-on-disk wear test apparatus. Disks of aluminum were tested in sliding against 440C stainless steel pins. The effects of key experimental parameters such as test environment, sliding velocity and applied load on the frictional behavior and on microstructure evolution were explored. Characterization techniques, including scanning electron microscopy...
The fretting corrosion behaviour of a Ti6Al4V alloy in contact with an alumina ball was investigated in a 0.9% sodium chloride solution. The tests were carried out using a fretting test rig equipped with an electrochemical cell. The effects of applied potential and oscillation frequency were evaluated for micro-motions of 50 and 100μm amplitude. Scanning electron microscopy (SEM) and Auger electron...
The study of wear mechanisms represents a very important task for the development of roll materials, with improved hot tribological properties. In the present paper the wear behaviour of different materials, i.e., high alloy steels (high speed steels (HSS)) and cast irons (high chromium irons (HiCr) and indefinite chill irons (IC)), produced by centrifugal casting, has been comparatively evaluated...
In a hot strip mill, the contact established between the hot strip and the work rolls in the first times of running has to be oxide on oxide to allow the strip to be pulled in the roll bite. The oxide scale formed on the roll is submitted to thermo-mechanical stresses and grows up. From a critical thickness, the scale spalls and causes some superficial damage to the rolls and to the strip.For the...
Aluminium diffusion-coated 9% Cr steel specimens were exposed to particles of two grades of silica sand, with similar particle size distributions but dissimilar angularities, in a fluidized-bed rig for 200h. The exposures were conducted at 550 and 600°C for particle impact angles of 30° and 90°, at speeds in the range 7–9.2ms −1 . The results show that the specimens experience only slight...
The adverse biological response to ultra-high molecular weight polyethylene (UHMWPE) wear debris in total joint replacement warrants the need for the material's improved wear resistance. The reaction of oxygen with radiation-induced free radicals within UHMWPE leads to oxidative degradation of the material. This work examines the effect of storing UHMWPE in vacuum at an elevated temperature (70°C)...
Ti–B–N thin films of ∼1.4μm in thickness with different B contents were deposited on Si(100) at room temperature by reactive unbalanced dc-magnetron sputtering. Dry sliding wear behaviors of Ti–B–N films were investigated by a traditional pin-on-disk test. The worn surface was observed using optical microscopy, scanning electron microscopy (SEM), and the wear debris was analyzed by energy dispersion...
Improvement of hot rolling process involves the lengthening of rolling campaigns. This can be achieved through the wear resistance improvement of work roll grades. The wear damage observed in service on the hot working rolls is the result of a complex interaction between oxidation, friction and thermal fatigue. An approach is to assess the coupled effect of oxidation and friction on the overall tribological...
The high-temperature tribological properties of a cathodic arc ion-plated (V,Ti)N coating have been investigated with a SRV high-temperature friction and wear tester. After heating in air at temperatures above 500°C, V 2 O 5 and TiO 2 phases were identified on surfaces of (V,Ti)N coating with V 2 O 5 -type platelets as the major oxidized product. (V,Ti)N coatings...
Applied magnetic field around the rotating sliding ferromagnetic steel/steel modifies the friction and the wear behaviour of the contact. The friction tests where conducted in ambient air or in high vacuum chamber 10 −5 Pa. The applied normal loads are 0.1, 18.5 and 37N. Without magnetic field, the contact is ductile steel against steel in a severe adhesive grooving mode. When a magnetic field...
A gamma-based titanium aluminide with the composition of Ti–45Al–2Nb–2Mn–1B (at%) was surface treated through a process in which thermal oxidation in air and diffusion were carried out in several steps to investigate the effect of oxide forming elements and diffusion of oxygen on the wear performance of surface layers. The microstructure and phases on the surface were characterized using optical and...
Transition metal nitrides exhibit excellent mechanical properties (hardness and Young's modulus), high melting point, good chemical stability and high electrical conductivity. However, tungsten nitrides still stand aside of the main attention. In our previous study, tungsten nitride coatings with different nitrogen content showed excellent wear resistance at room temperature. Nevertheless, many engineering...
Effect of low sliding speeds (0.01–1.0ms −1 ) on wear behaviour of an AZ91D magnesium alloy was studied under dry sliding condition using a pin-on-disc configuration. The wear rates were measured under a constant load of 10N but two different sliding distances (1 and 10km). Analyses of the wear tracks, worn surfaces and wear debris were carried out using scanning electron microscope and X-ray...
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