IJMET_09_12_070.pdf

Polymer and their composites are finding ever increasing usage for numerous industrial applications such as bearing material, rollers, seals, gears, cams, wheels and clutches. Many researchers are focusing on the wear behavior and to improve the wear resistance of polymeric composites. A pin-on-disc setup (Magnum Engineers, Bangalore) was used for wear experiments. The Results of wear properties of vinyl ester-Glass fibre composites with varying percentage of TiO2, Al2O3 and MoS2 filled composites were presented in the present paper. The wear loss increases with increase in sliding velocity and load. Fillers filled composite materials having high wear resistant and low specific wear rate. The hardness of filled composite was substantial compared to hardness of unfilled composite.

The dry wear of polytetrafluoroethylene (PTFE)-based composites, including bronze-filled composites (B60), glass-filled composites (G15), and carbon-filled composites (C25), produced by the mold casting method were investigated under different sliding conditions. The Taguchi L27 method and the analysis of variance were used to identify the effect of process parameters on the wear of tested materials. Experimental results showed that the wear resistance of G15 polymer composites was better than those of C25 and B60 ones. The specific wear rate decreased with increasing sliding distance and load, but partly decreased with increasing tensile strength.

The effects of two types of filler reinforcements i.e. particulate (talc particles) and fiber (Glass Fiber (GF)) as secondary reinforcements in ultra-high molecular weight polyethylene (UHMWPE)-based composites on the wear and friction properties were discussed in this paper. These UHMWPE hybrid composites were fabricated by the addition of 10 wt% of talc and glass fiber at a fixed nano-ZnO loading of 10 wt% using a hot compression moulding technique. The wear and friction properties of these hybrid composites were investigated using a pin-on-disc tester with different operating conditions of applied loads, sliding speeds and sliding distances based on response surface Box-Behnken design. Response Surface Methodology (RSM) was applied to model the effects of various variables of applied load, sliding speed and distance on the wear volume loss and average coefficient of friction (COF) of UHMWPE hybrid composites. 2 The mathematical regression models of the wear volume and average COF were derived from the analysis of variance (ANOVA). Optimization of the independent variables to minimize the wear and friction responses of both UHMWPE composites was estimated using RSM. The mathematical models showed that applied load, sliding speed and distance have significant effects on the wear and friction properties of both UHMWPE composites in the tested range of variables. The most significant, in order of the variables that affect the volume loss and friction of UHMWPE composites is load, followed by sliding distance and speed. In addition, the combined effects of load and distance indicate the highest significance on volume loss and average COF for both UHMWPE hybrid composites as compared to other variable interactions. GF/ZnO/UHMWPE exhibited better wear performance compared to talc/ZnO/UHMWPE hybrid composites. The severity of worn surfaces of the GF/ZnO/UHMWPE was less than that of talc/ZnO/UHMWPE. The GF/ZnO/UHMWPE produced transfer films that were more uniform and had better coverage compared to talc/ZnO/UHMWPE.

Wear, 2004

The influence of short fiber reinforcement and solid lubricants is widely studied in rotational sliding adhesive wear mode, but not much is reported in low amplitude oscillating wear situation. In this paper a series of polyetherimide (PEI) composites with increasing amount of short glass fibers (GF) 10-40% in the step of 10%, was selected for investigating the influence of GF on friction and wear. A composite containing 25% GF and three solid lubricants was also selected to examine the influence of solid lubricants in the presence of GF. The studies were conducted under various loads and temperatures on a SRV Optimol tester. It was observed that the coefficient of friction was constant irrespective of the amount of GF in PEI, load, temperature and sliding duration. The inclusion of solid lubricants, however, reduced it significantly. Wear behavior, on the other hand, was benefited due to the presence of GF and lubricants as well. Among all GF reinforced composites 10% inclusion of GF showed highest wear resistance. Further inclusion of lubricants improved it significantly. With increase in load and temperature, the specific wear rate increased marginally for the composites and substantially for the PEI. SEM proved to be helpful in understanding the wear mechanisms.

Dental Materials, 2006

Objectives: The aim of the study was to evaluate two ceramic materials as possible substitutes for enamel using two wear simulation methods, and to compare both methods with regard to the wear results for different materials. Methods: Flat specimens (OHSU n=6, Ivoclar n=8) of one compomer and three composite materials (Dyract AP, Tetric Ceram, Z250, experimental composite) were fabricated and subjected to wear using two different wear testing methods and two pressable ceramic materials as stylus (Empress, experimental ceramic). For the OHSU method, enamel styli of the same dimensions as the ceramic stylus were fabricated additionally. Both wear testing methods differ with regard to loading force, lateral movement of stylus, stylus dimension, number of cycles, thermocycling and abrasive medium. In the OHSU method, the wear facets (mean vertical loss) were measured using a contact profilometer, while in the Ivoclar method (maximal vertical loss) a laser scanner was used for this purpose. Additionally, the vertical loss of the ceramic stylus was quantified for the Ivoclar method. The results obtained from each method were compared by ANOVA and Tukey's test (p<0.05). To compare both wear methods, the log-transformed data were used to establish relative ranks between material/stylus combinations and assessed by applying the Pearson correlation coefficient. Results: The experimental ceramic material generated significantly less wear in Tetric Ceram and Z250 specimens compared to the Empress stylus in the Ivoclar method, whereas with the OHSU method, no difference between the two ceramic antagonists was found with regard to abrasion or attrition. The wear generated by the enamel stylus was not statistically different from that generated by the other two ceramic materials in the OHSU method. With the Ivoclar method, wear of the ceramic stylus was only statistically different when in contact with Tetric Ceram. There was a close correlation between the attrition wear of the OHSU and the wear of the Ivoclar method (Pearson coefficient 0.83, p=0.01). Significance: Pressable ceramic materials can be used as a substitute for enamel in wear testing machines. However, material ranking may be affected by the type of ceramic material chosen. The attrition wear of the OHSU method was comparable with the wear generated with the Ivoclar method.

Wear, 2004

The oscillating wear failure of the materials is frequently observed in various tribo-applications such as bearings, gears, bushes, palliatives, bolted and riveted joints and seals, etc. where oscillations of small amplitude or vibrations are inevitable. In general, the oscillating wear performance of the materials depends on the amplitude of oscillation, its frequency and duration, load, contact geometry, environment, etc. A vast literature is available reporting on the influence of fillers and fibres on the adhesive (unidirectional) and abrasive wear behaviour of polyamides (PAs) but not much on their oscillating wear behaviour. For the present study, PA 11 and its three composites containing short glass fibres (GF) and metallic powdery fillers such as bronze and copper were selected for the investigations. Experiments were carried out on the SRV Optimol instrument in pin on disc configuration, under various loads at room temperature. It was observed that the GF reinforcement greatly improved the friction and wear performance of PA 11. Incorporation of bronze and copper powders in GF reinforced composite further improved the friction and wear behaviour of PA 11. Copper proved to be beneficial filler than the bronze in this context. Worn surface studies were also done to investigate the wear mechanisms. The SEM and EDAX studies on the copper-containing composite indicated that the film transfer on the disc was very thin, uniform and coherent. It showed evidence of Cu transfer on the disc, which was thought responsible for strong adherence of the film to the mild steel disc resulting in the best friction and wear behaviour of the composite.

Tribology International, 2017

The aim of this work was to compare the effect of vinyl ester reinforced with Musaceae fiber bundles on tribological behavior while varying the composite´s fiber content and the counter-body's material and surface roughness. Pin-on-disc test equipment was used to slide composites while keeping the test parameters fixed. SEM images were used to identify the wear mechanisms. Results demonstrate that composites have better wear resistance than neat resin but lack a clear behavior when fiber content is increased. The best material was the composite reinforced with 10 wt% fiber. The primary wear mechanisms identified were adhesion, surface fatigue, crazing, fiber debonding and fractures. The transferred layer and debris are directly related to the discs' roughness and not to their material.

Wear, 2008

Wear, 2017

Poly aryl ether ketone (PAEK) is known as a high performance polymer superior to PEEK (poly ether ether ketone) in many aspects such as temperature stability, tribo-performance etc. Recently few efforts are put to enhance the tribo-potential of PAEK by developing composites containing short fibers of carbon and glass and most favored lubricants such as graphite, PTFE (poly tetrafluoroethylene), hexa boron nitride (hBN) etc. The wear and friction got significantly reduced to the extent that the composites showed very high potential as bearing materials for harsh operating conditions. Mica and boric acid (BA) are known as very good solid lubricants (SLs) with layer lattice structures. Potassium titanate (KT) powder also has been very popular ingredient of friction materials responsible for increasing wear resistance (W R) and reducing friction fluctuations. It is, however, never explored in bearing materials for enhancing tribo-potential. Keeping this in view, a series of composites was prepared by injection molding with identical parent composition but differing in type of solid lubricants (hBN, KT, BA and Mica). The tribo-performance was evaluated in adhesive wear mode on tribometer under severe operating conditions (700-900 N, velocity 1.63-3.5 m/s). Composites exhibited very low specific wear rates (K 0) (2-8 Â 10-16 m 3 /Nm) and very low coefficient of friction (m) (0.04-0.08), which decreased with load and velocity. KT proved to be the most performing filler, while Mica was least effective followed by BA. Worn surface analysis by SEM (Scanning electron microscopy) and EDAX (energy dispersive x-ray) helped to understand wear mechanisms.