Solid particle erosion behaviour of glass fibre reinforced boric acid filled epoxy resin composites

The tests which involved angular aluminium (Al₂O₃) particles with two different sizes of approximately 200 and 400 μm were conducted at the operating conditions namely different impact velocities of approximately 23, 34 and 53 m/s, two different fibre directions [0° (0/90) and 45° (45/−45)] and three different impingement angles of 30°, 60° and 90°. New composites with addition of Boric Acid filler material at 15% of resin exhibited upper wear than the neat materials without filler material. This means the filler material has decreased the erosion wear resistance. SEM views showing worn out surfaces of the test specimens were scrutinised.     

Solid particle erosion of unidirectional fibre reinforced thermoplastic composites

In the present study, the solid particle erosion behaviour of neat PEEK matrix and unidirectional glass fibre (GF) and carbon fibre (CF) reinforced polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) composites has been studied. The erosion experiments have been carried out by using silica sand particles (200 ± 50 μm) as an erodent. Steady state erosion rates of these composites have been evaluated at different impact angles and impact velocities. The neat PEEK exhibited peak erosion rate at 30° impingement angle whereas the composites exhibited a semi-ductile behaviour with peak erosion rate at 60° impact angle. The erosion rate of the glass fibre reinforced composites was higher than that of the carbon fibre reinforced composites. The results show that the fibre orientation has a significant influence on erosion rate only at lower impact angles. The erosion rate of the composites was higher when the particles impact perpendicular to the fibre direction than parallel to the fibres. The morphology of eroded surfaces was observed under scanning electron microscope and damage mechanisms were discussed.     

Solid particle erosion of unidirectional carbon fibre reinforced polyetheretherketone composites

The solid particle erosion behaviour of unidirectional carbon fibre (CF) reinforced polyetheretherketone (PEEK) composites has been characterised. The erosion rates of these composites have been evaluated at different impingement angles (15–90°) and at three different fibre orientations (0, 45, and 90°). The particles used for the erosion measurements were steel balls with diameter of 300–500 μm and impact velocities of 45 and 85 m/s. The unidirectional CF reinforced PEEK composites showed semi-ductile erosion behaviour, with maximum erosion rate at 60° impingement angle. The fibre orientations had a significant influence on erosion rate. The morphology of eroded surfaces was examined by using scanning electron microscopy (SEM). Possible erosion mechanisms are discussed.     

Tribological behaviour of glass fibre bundles reinforced epoxy gradient composites

Abstract

The short fibre bundles separated from the machining waste of a printed circuit board manufacturing plant were used in preparing functionally graded composites using polysulphide modified epoxy resin. Glass fibre bundles were thouroughly mixed with epoxy, which is getting polymerised with time and centrifugal force was applied to achieve graded dispersion of glass fibre bundles. The centrifugation time was varied to obtain different gradient profiles. Optical microstructures confirmed the graded dispersion of glass fibres bundles in the epoxy matrix. Increase in distance towards the centrifugation force direction increases the glass fibre concentration. Gradient characteristics in the composite have been observed in wear and friction measurements, which were conducted using a pin-on-disc machine. Worn surfaces of samples were analysed with the help of SEM. Both sliding (adhesive) and abrasive wear rates of glass fibre reinforced epoxy gradient composites reduced with increasing centrifugation time. Reduction in wear rate in glass fibre epoxy gradient composites has been attributed to the better interface bonding between epoxy coated fibre bundles and the epoxy matrix and hardening property of glass fibre. It has been found that capability to sustain pressure limit increased from 0·59 to 0·79 MPa on centrifuging the sample upto 2 min and reached to 1·19 MPa with increasing the centrifugation time to 30 min.     

Wear behaviour of carbon nanotube reinforced epoxy resin composites

This paper deals with the effect of a multi-walled carbon nanotube (MWCNT) reinforcement on the wear behaviour of Epoxy (EP) composites. Firstly, various dispersion methods were compared. Secondly, the optimum CNT amount was evaluated. In a third step, dry lubricants were added to the optimised EP/CNT composite. Finally, the influence of the steel counterpart (martensitic bearing steel 100Cr6 and austenitic stainless steel X5CrNi18-10) was studied. The preparation method was found to have a decisive effect on the wear behaviour of the composite. A pre-treatment of the CNTs in concentrated nitric acid proved beneficial. Even more important was the mixing method. A dual asymmetric centrifuge delivered so good wear results that the pre-treatment could be skipped. The optimum CNT content was at about 1 wt%, regardless of the preparation method. The lowest wear rates were found after addition of 10 wt% graphite. MoS₂ proved to be less effective and Polytetrafluorethylene (PTFE) even increased the wear. The wear rates against the unalloyed martensitic steel were far higher than against austenitic stainless steel.     

Tribo-mechanical properties of glass fibre reinforced polypropylene composites

Fibre reinforced polypropylene (PP) composites are frequently used for structural applications. In this context, it is of particular importance how much the tribological properties of PP can be improved by fibre reinforcement. Based on experimental investigations, this issue is discussed in the article by studying the tribo-mechanical properties of different PP composites. The relevant parameters of friction and wear are presented in order to provide a comprehensive data set for applications. Additionally, the wear mechanisms are studied phenomenologically by means of optical microscopy. It was shown that the tribo-mechanical properties of PP can be significantly influenced with a suitable reinforcement.     

Solid particle erosion wear characteristics of fiber and particulate filled polymer composites: A review

The solid particle erosion behaviour of fiber and particulate filled polymer composites has been reviewed. An overview of the problem of solid particle erosion was given with respect to the processes and modes during erosion with focus on polymer matrix composites. The new aspects in the experimental studies of erosion of fiber and particulate filled polymer composites were emphasised in this paper. Various predictions and models proposed to describe the erosion rate were listed and their suitability was mentioned. Implementation of design of experiments and statistical techniques in analyzing the erosion behaviour of composites was discussed. Recent findings on erosion response of multi-component hybrid composites were also presented. Recommendations were given on how to solve some open questions related to the structure-erosion resistance relationships for polymers and polymer based hybrid composites.     

Friction properties of sisal fibre reinforced resin brake composites

Using a constant speed tester, the friction and wear characteristics of sisal fibre reinforced brake composites with different contents at separate friction temperatures were studied, and its tribology and wear character were discussed. It's showed that the friction and wear properties of sisal brake composites reach the optimum point when the proportion between resin and sisal fibre is 3:4. Compared with asbestos and mineral/steel fibre, sisal fibre reinforced friction composites shows that the friction coefficient is good for fitting with low wave rate at different friction temperatures. The sisal is an ideal substitute of asbestos for brake pads.     

Development and tribological behaviour of UHMWPE filled epoxy gradient composites

In this study, ultra high molecular weight polyethylene (UHMWPE) filled epoxy gradient composites have been developed. Samples were prepared for different centrifugation time periods. SEM and optical microstructures confirmed the graded dispersion of UHMWPE particles in the epoxy matrix. Quick estimation of gradient characteristics has been done by abrasive wear measurements. Sliding wear tests were conducted by using a pin-on-disc machine. The sliding wear rate of composites reduced on increasing centrifugation time. Reduction in sliding wear rate in UHMWPE filled epoxy gradient composites has been attributed to the reduction of tensile contact stresses as a result of the lubricating effect of UHMWPE's smooth surface and highly entangled chain structure of UHMWPE.     

Solid particle erosion behaviour of Ti6Al4V alloy

Abstract

The effects of particle impingement angle, impingement velocity and erodent particle size on the erosion rate and surface morphology of the Ti6Al4V alloy have been investigated comprehensively in order to evaluate solid particle erosion behaviour of Ti6Al4V alloy. Samples were eroded in a specially designed sandblasting system under various parameters using alumina (Al₂O₃) erodent particles. Surface morphology investigations were examined by scanning electron microscope using various analysis and modes (energy dispersive X-ray analysis, elemental mapping and compositional contrast). Ti6Al4V alloy showed ductile behaviour with a maximum erosion rate at 30° impingement angle. Erosion rate of Ti6Al4V alloy increased with increases in velocity and decreased with increases in erodent particle size. Scanning electron microscopy investigations of eroded surfaces of Ti6Al4V alloy samples reveal the dominant erosion mechanism such as microploughing, microcutting and plastic deformation. Embedded erodent particles on the surfaces of Ti6Al4V alloy nearly at all particle impingement angles and velocities were clearly detected.     

Investigation on solid particle erosion behaviour of polyetherimide and its composites

The present investigation reports about, the solid particle erosion behaviour of randomly oriented short E-glass, carbon fibre and solid lubricants (PTFE, graphite, MoS₂) filled polyetherimide (PEI) composites. The erosion rates (ERs) of these composites have been evaluated at different impingement angles (15–90°) and impact velocities (30–88 m/s). Mechanical properties such as tensile strength (S), ultimate elongation to fracture (e), hardness (H_V), Izod impact strength (I) and shear strength (S_s) seems to be controlling the erosion rate of PEI and its composites. Polyetherimide and its glass, carbon fibre reinforced composites showed semi-ductile erosion behaviour with peak erosion rate at 60° impingement angle. However, glass fibre reinforced PEI composite filled with solid lubricants showed peak erosion rate at 60° impingement angle for impact velocities of 30 and 88 m/s, whereas for intermediate velocities (52 and 60 m/s) peak erosion rate observed at 30° impingement angle. It is observed that 20% (w/w) glass fibre reinforcement helps in improving erosive wear resistance of neat PEI matrix. Erosion efficiency (η) values (0.23–8.2%) indicate micro-ploughing and micro-cutting dominant wear mechanisms. The morphology of eroded surfaces was examined by using scanning electron microscopy (SEM). Possible erosion mechanisms are discussed.     

Dry sliding wear of short glass fibre reinforced zinc–aluminium composites

The present investigation aims to evaluate the wear rate of ZA-27 alloy composites reinforced with short glass fibres from 1 to 5% in steps of 2 wt%. The compocasting method was used to fabricate the composites. A pin-on-disc wear testing machine was used to evaluate the wear rate. The results indicated that the wear rate of the composites was less than that of the matrix alloy, but increased with the increase in load and the sliding distance. It was found that above a critical applied load, there exists a transition from mild to severe wear both in the unreinforced alloy and in the composites, but the transition loads for the composites are much higher than that of the unreinforced alloy, and increases with the increase in weight% of glass fibres. The observations have been explained using scanning electron micrography (SEM) analysis of the worn surfaces and the subsurface of the composites.     

Solid particle erosion studies on biomorphic Si/SiC ceramic composites

Solid particle erosion tests were conducted on four different types of silicon carbide ceramic composites. The composites are cotton fabric based Si/SiC with and without chemical vapour infiltration, fine teak wood powder based Si/SiC and coarse teak wood powder based Si/SiC. The erodents used are angular SiC particles of average size 80, 250 and 450 μm. The velocities with which particles impacted on the target materials were varied from 20 to 50 m/s. Similarly the angle of impact was varied from 20° to 90°. Scanning electron microscopic observations on the eroded surface show brittle and cleavage like fracture. Fine teak wood powder based Si/SiC ceramic shows better erosion resistance than the other ceramics. Homogenous distribution of SiC grains with the presence of very fine grains of silicon and carbon is responsible for the improved erosion resistance. The higher erosion rate in cotton fabric based SiC arises from its microstructure. Here, the free carbon and free silicon grains are large in size and the SiC phase has very low hardness as compared to the erodent.     

Mechanical properties of inorganic particle reinforced epoxy composites for gas insulated switchgear

In this study, the particle reinforced epoxy composite with alumina and silica was considered to insulation material for the gas insulated switchgears (GIS     

Solid particle erosion of mullite

The solid particle erosion of mullite (3Al₂O₃·2SiO₂ plus approximately 12% glass phase) was investigated using angular A1₂O₃ particles whose mean diameters D were varied between 23 and 270 μm. A range of impact angles α between 15° and 90° was used and the impact velocity V was varied from 60 to 100 m s^?1. The results of these experiments are in agreement with the general predictions of the two models developed to describe erosion in brittle materials on the basis of the formation of lateral cracks. The velocity exponent of the steady state erosion rate ΔW is between 2.2 and 2.8, being larger for smaller particles. For normal incidence, $\text{ΔW ∝ D}{}^{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}$ in accord with both theories. For α > 15° only the normal component of velocity need be considered, but for smaller α there is evidence of plasticity both in the α dependence of ΔW and as observed using scanning electron microscopy.     

Solid particle erosion behaviour of metallic materials at room and elevated temperatures

The behaviour of metallic materials subjected to solid particle erosion has been studied extensively over the last few decades. It is not the purpose of this paper to provide a comprehensive review of the above body of work especially since many such reviews already exist. Rather, the aim of this paper is to describe briefly the salient features characteristic of room temperature and elevated temperature erosion of metallic materials and follow it up with a review of some of the recent results, which in our opinion, have enhanced our current understanding in the area of solid particle erosion of metallic materials. As a natural consequence, the paper concludes with a critical review of the areas which require further study.     

Solid particle erosion studies on polyphenylene sulfide composites and prediction on erosion data using artificial neural networks

Solid particle erosion behavior of polyphenylene sulfide, reinforced by short glass fibers with varying fiber content (0–40 wt%) has been studied. Steady-state erosion rates have been evaluated at different impact angles (15–90°) and impact velocities (25–66 m/s) using silica sand particles (200 ± 50 μm) as an erodent. PPS and its composites exhibited maximum erosion rate at 30° impact angle indicating ductile erosion behavior. Though PPS is a brittle thermoplastic, incubation period was found for neat resin and its composites at normal impact (α = 90°). The erosion rates of PPS composites increased with increasing amount of glass fiber. Morphology of eroded surfaces was examined using scanning electron microscopy (SEM) and possible wear mechanisms were discussed. Also, artificial neural networks (ANNs) technique has been used to predict the erosion rate based on the experimentally measured database of PPS composites. The results show that the predicted data are well acceptable when comparing them to measured values. A well-trained ANN is expected to be very helpful for prediction of wear data for systematic parameter studies.     

The tribological behaviour of glass filled polytetrafluoroethylene

Polymers and polymer composites are steadily gaining ground over metals in the field of engineering applications in tribology. Laboratory wear tests were carried out under ambient temperatures with no lubricant as well as in distilled water at an average sliding velocity of 0.2 m/s and contact pressures of 2.6–6.4 MPa. Three forms of glass viz. glass fibres, glass beads and glass flakes, each with a content of 25% weight were used in this study. Both hollow and solid glass beads were used. The sliding wear of the different glass filled PTFE composites was dependent on their ability to form transfer films on the counterface. The glass bead filled PTFE showed comparatively thicker films and higher wear rates than other forms of glass filled grades. The glass fibres and solid glass beads showed the lowest wear whilst hollow beads showed the highest under both low and high pressures due to crumbling and crushing of the beads during the sliding process. The glass flake filled PTFE showed relatively high but stable wear results up to 4.5 MPa above which the wear rate increased dramatically. A marginal increase in wear was achieved by using high aspect ratio glass fibres to the PTFE matrix. No correlation between the size of glass reinforcement and wear rate was established. The addition of a lamellar solid lubricant to the glass fibres reduced both the wear and friction of PTFE. The study of the transfer film growth by means of an optical microscope revealed that it was due to the mechanical interlocking of the polymer fragments into the metal asperity valleys. The compositional changes in the transfer film were studied by XPS which, among other things, showed presence of metal fluoride on the metal counterface.     

Measurements of fibre direction in reinforced polymer composites

High-quality data on the three-dimensional (3-D) spatial distributions of glass and carbon fibres in fibre-reinforced polymer composites are important for both process control and the modelling of the mechanical and thermal properties of these composites. The advent of economical, high-speed, image analyser systems has enabled numerous research groups to measure directional distributions of fibre samples. Specimens are microtomed and polished and, using optical reflection microscopy, thousands of elliptical fibre images may be analysed within a short period of time. From the eccentricity of the fibre images, estimation of the angles (θ, φ) of each fibre relative to the vertical axis and within the measurement plane is deduced. However, this measurement is subject to considerable error. The confocal scanning laser microscope (CSLM), operating in fluorescence mode or reflection mode, is capable of improving the angular resolution (δθ, δφ) for all fibre directions. The ability of the CSLM to optically section glass and carbon fibre-reinforced polymer composites down to depths of 20 or 30 μm allows the user to determine accurate fibre directions from the apparent movement of fibre profiles. The CSLM has the potential for standardizing measurements of 3-D fibre directions in polymer composites and providing the quality directional data which are required for the theoretical modelling of composite processing and composite strength.     

Effects of fibre content and relative fibre-orientation on the solid particle erosion of GF/PP composites

The erosive wear behaviour of glass fibre (GF) reinforced thermoplastic polypropylene (PP) composites was studied in a modified sandblasting apparatus as a function of the impact angle (30, 60 and 90°), relative fibre-orientation (parallel Pa and perpendicular Pe), fibre length (discontinuous, continuous) and fibre content (40–60 wt.%).The results showed a strong dependence of the erosive wear on the relative fibre-orientation at low impact angles (30°), but hardly any difference for 60 and 90° impact angles. In contrast, the fibre length did not affect the erosive wear behaviour especially at high impact angles.The inclusion of brittle GF led to higher erosive wear rates (ER) of the GF/PP composites; the higher the fibre content, the higher was the ER. Nevertheless, the composites still failed in a ductile manner. Different approaches proposed to describe the relationship between ER and fibre content were applied. Best results were generally delivered with the inverse rule of mixture. The modified rule of mixtures proposed for abrasive wear do not seem to apply for erosive wear.