Papers by Keyword: Worn Surface

Abstract: In the present scenario aluminium is an useful metal due its admirable properties such as light weight, low cost and excellent thermal conductivity.In order to take advantages of these properties aluminium is being used to make the metal matrix composites for tribological application, In this present investigation effort has been made to assess the wear properties of Al–B₄C–Gr metal matrix composite at various temperatures such as 323° K, 373° K and 423° K. Al–B₄C–Gr Hybrid metal matrix composites were fabricated by stir casting technique. The influence of parameters like load, speed, distance and temperature on the wear rate was investigated. A plan of experiments, based on Taguchi model with L27 orthogonal array and analysis of variance was employed to investigate the influence of process parameters on the wear behaviour of these hybrid metal matrix composites. The wear resistance increased with increasing temperature, but wear resistance decreased at higher loads. It was observed that the abrasive wear is dominates while sliding as observed by SEM analysis of worn out specimens.

Abstract: An attempt has been made to study the dry sliding wear behaviour of Aluminium based hybrid composites in room temperature.Al 2219 is used as base material with B₄C and MoS₂ as reinforcements. The hybrid composite were prepared by conventional stir casting technique. The dry sliding wear test were carried out for various parameters like sliding distance, applied load and sliding speed. The Optical Microscope and SEM results showed the presence of B₄C and MoS₂, which are fairly uniform and randomly dispersed on matrix material.XRD analysis, shown the presence of B₄C and MoS₂ phases in the prepared composites.The incorporation of reinforcement particles B₄C and MoS₂ reduces the specific wear rate of composites. The addition of MoS₂ as a secondary reinforcement has significant effect on reducing specific wear rate of prepared composites. By using SEM worn surface of hybrid composites were studied.

Abstract: Based on the multi-fractal theory and SEM image, the multi-fractal property of the plant abrasive to metal surface was studied. The result shows that the characteristic parameters of △α and △f of the multi-fractal spectrum on can reflect the morphology features of the worn surface, which are connected with volume wear, so they are regarded as characterization parameters in quantification on the surface of metallic material that is worn by plant abrasive. 15 mm.

Abstract: We study systematically the morphology and graphitization of the worn surface of C/C composite with rough lamination/smooth lamination/resin carbon (RL/SL/RC) as matrix precursor tested by using M2000 wear tester with a couple of Cr-coated 40 Cr steel. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses indicate that the worn surface of RL/SL/RC is integrated. Particles with the size of 100~300 nm could be found on the worn surface. The leaning-angles of the particles against the sliding direction on the worn surface are between 30 ° and 50 °. Raman laser spectrum (RLS) analysis reveals that, after the wear test, the graphitization on the worn surface of RL/SL/RC decreased with the increase in load, but graphitization of the fiber kept constant and that of the boundary increased up to 150 N. The surface graphitization of different components became closer and closer with the increase in load.

Abstract: Palm fatty acid distillate (PFAD) has potential to be used as a lubricant. PFAD is a by-product from palm oil refinery, and it is classified as non-edible oil. However, vegetable oil has poor thermal performance and high oxidation rate. In this paper, the tribological performance of PFAD in different working temperature was investigated by using four-ball tribotester. Tests were conducted at temperatures 50oC, 75oC, 100oC and 125oC, under a normal load of 40 kg for one (1) hour. The rotational speed was set at 1200rpm. Similar tests were conducted using industrial hydraulic oil as a comparison lubricant. Analyses were focused on the coefficient of friction (CoF), wear scar diameter (WSD) and worn surface observation. Results show that coefficient of friction and wear were increased with the increment of temperature. However, palm fatty acid distillate show a better performance in term of friction reduction compared to industrial hydraulic oil.

Abstract: One of the main disadvantages of vegetable oil as an industrial lubricant is its poor performance at high temperature. In this experimental work, the performance of refined, bleached and deodorized (RBD) palm olein was tested at different operating temperatures using four-ball tribometer, following the procedure of ASTM D 4172. The result produced by RBD palm olein was compared with the result by additive free paraffinic mineral oil. The result showed that the RBD palm olein had lower coefficient of friction compared to the paraffinic mineral oil. However, the wear scars on the ball bearings surface lubricated with RBD palm olein were larger compared to those lubricated with paraffinic mineral oil.

Abstract: Effect of peak-aged and over-aged Cu particles on wear behaviour of ferritic iron was investigated by means of Pin-on-Disc wear test under dry sliding condition. It was found that hardness of the peak-aged sample was higher than the over-aged sample. The specific wear rates of peak-aged samples were in the range of 0.20 × 10-4 to 0.89 × 10-4 mm3/(Nm) while the over-aged samples were in the range of 0.21 × 10-4 to 1.29 × 10-4 mm3/(Nm). Although both samples possessed moderate wear behaviours, the peak-aged samples had better wear resistance. Scanning Electron Microscopy observation found that most wear mechanism were due to plastic ploughing phenomenon. Transferred materials from the counterface tool was also proven by Energy Dispersive Spectroscopy test. However, the roughness test showed that the peak-aged sample surface was finer than the over-aged sample surface. Average roughness of peak-aged samples were in the range of 0.49 to 1.79 μm while the over-aged samples were in the range of 3.28 to 4.02 μm. Hence, it can be concluded that the peak-aged Cu particles can improve the wear resistance of steel.

Abstract: There is a growing interest in the application of ceramic as high wear resistance materials due to the unique properties. Although brittleness and low toughness, recent improvements in alumina processing have lessen this restrictions and suggest improvements in wear resistance which in turn have driven some research on this. Since a direct comparison between the many published works regarding this wear improvement is complicated due to the fact that wear resistance is a response of the microstructure, material and testing condition, the work herein presented aims to first do a literature review on the main parameters to be controlled in a pin-on-disc apparatus on the wear of alumina and then discuss preliminary test results and analyze the influence of critical parameters as load and sliding speed in a pin-on-disc wear test in a dense and sub micrometer grain size alumina.

Abstract: The worn surface is usually coated with a layer, which thickness exceeds magnitude of wear. In order to provide required clearances (or tightness) in the assembling of parts, uniform clearances (this suggests the presence of the perfect mating should be provided. In the paper, the effects on the layer were discussed and forecasting the clearance sizes or (when the limit values are specified) determining the assembly life. In the process of repairing, the worn surface is usually coated with the layer, which thickness exceeds magnitude of wear. After the surface is coated it is machined by one of the available methods. During recent years, new so-called “cold” methods of coating have appeared, some of them (particularly galvanomechanical machining) enables to obtain required dimensions and quality metrics of surface layer without complete machining. The final goal of repair is to provide required clearances (or tightness) in the assembling of parts. It is required to provide uniform clearances (this suggests the presence of the perfect mating surfaces before assembly). Depending on accuracy grade, variations in the clearance dimensions may be within the limits from some microns to decile of millimeter. This depends on mating surface accuracies and is independent of the fact whether these surfaces were repaired or not. If the parts were machined separately, thickness of the layer shall be determined subject to the actual size of mating part areas, size and dimensional tolerances of clearance. When developing the process of parts repair, the following shall be considered: - wear degree of contact mating locations; - requirements for quality of surface layer in part assemblies; - permissible errors of mating surfaces; - allowance (or tightness) between mating parts and its variation limits in the assembly. The wear in mating locations is determined by supervision of part defects before repair. The limiting wear of products shall not exceed capability of galvanomechanical method. It is required for qualitative surface coating to limit the thickness to 0,5-0,6 mm. Depending on wear degree, two methods of repair can be used: -smoothing of macrosurface with a galvanomechanical coating, for example with chromium and thereafter application of qualitative surface layer. Such process shall be applied in the case when degree of surface unevenness does not exceed 50%. If wear degree is out of the stated limits, preliminary machining is required. This machining is necessary to reduce surface unevenness up to 50%. After this procedure, effective thickness of coating shall be applied. The acceptable surface unevennesses with different degrees of wear are shown on Fig.1 At the first stage of coating the stock shall be evened. After this, the surface roughness does not exceed the roughness coefficient specified for a new part, but other quality indexes of the surface (residual stress character, wear-resistance) are not in conformance with the requirements for the repaired parts. Therefore, after evening, another “slower” method of galvanomechanical repair with specified contact pressure and mechanical effect conditions is applied. As a result of this method, the following indexes are available. See Table 1.

Abstract: In this study, the mechanical properties of silica-filled epoxy resin composites with average silica particle diameter of 6-33m were investigated at ambient temperature and pin-ondisc friction test was conducted for this. Experimental results demonstrated that mechanical properties such as flexural strength, flexural modulus and critical stress intensity factor depend on average particle diameter. The flexural strength decrease with increase of particle size whereas the critical stress intensity factor increases with increases of particle size. Wear rates of silica-filled composites are below a half those of unfilled epoxy. Fracture surface analysis was discussed based on SEM examination.