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.     

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.     

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.     

Experimental and Simulation Studies on the Solid-Particle Erosion of WC-MgO Composites

This article reports our recent studies on WC-4.3 wt% MgO composites with a particular interest in the effect of grain-growth inhibitors (VC and Cr₃C₂) addition on its resistance to erosive wear. It is shown that the maximum erosion rate of the WC-MgO composite occurred at an impingement angle of 90°. With the addition of the grain-growth inhibitors (0.25 wt% VC and 0.25 wt% Cr₃C₂), the erosion resistance increased, particularly profound at the impingement angle of 90°, due to refined microstructures with improved mechanical properties. In addition, computational simulation based on a microscale dynamic model was conducted to investigate the effects of the grain boundary strength and grain size on the erosion resistance of the WC-MgO composites in order to better understand the microstructural effect on the erosive performance of the composites. It is demonstrated that the grain refinement with weak grain boundary strength has a negative effect on the erosion resistance.     

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.     

General method for predicting the sand erosion rate of GFRP

Sand erosion behavior and wear mechanism of various types of glass fibre reinforced plastics (GFRP) were investigated. Erosion behavior of fibre reinforced plastics (FRP) changed from ductile manner to brittle one with increase of glass fibre content, and erosion rate was maximum at vertical impact for higher glass fibre content FRP. FRP showed higher resistance to erosion damage than resin matrix at low angle of attack, the contrary tendency can be observed at higher angle of attack. The importance of damage of glass fibre bundles accompany with surrounding resin and effect of orientation angle of fibres on erosion damage of FRP were pointed out. Based on these factors and applying similar equation of the rule of mixture for strength of FRP, prediction method for erosion rate was proposed.By using this method, erosion rates of all types of GFRP under various angles of attack and impacting velocity can be estimated by knowing only the rate of matrix resin.     

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.     

Erosive wear of ductile metals by a particle-laden high velocity liquid jet

A liquid-solid particle jet impingement flow apparatus is described and experimental measurements are reported for the accelerated erosion of copper, aluminum and mild steel sheet metal by coal suspensions in kerosene and Al₂O₃ and SiC suspensions in water. Slurry velocities of up to 130 ft s^?1 (40 m s^?1) and impingement angles of 15°–90° were investigated. The maximum particle concentration used was 40 wt.%. For high velocity the results of this work show two erosion maxima; these are found at impingement angles of 90° and 40°. However, in corresponding gas-solid particle investigations maximum erosion occurs at approximately 20°. In this work both particle concentration and composition were varied. A polynomial regression technique was used to calculate empirical and semitheoretical correlation constants.     

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.     

Slurry Erosion Wear Resistance and Impact-Induced Phase Transformation of Titanium Alloys

Erosion wear resistance and impact-induced phase transformation of titanium alloys TA2 (pure Ti), TC4 (Ti–6Al–4V) and TC11 (Ti–6.5Al–3.5Mo–1.5Zr–0.3Si) were investigated using a slurry jet tester. The slurry erosion wear resistance of TA2 is comparable to that of 304 stainless steel, especially at the impingement angle 90°. Although TC4 and TC11 have higher hardness, TA2 possesses the best erosion wear resistance except TC11 at 15°. With the increasing erosion time, the eroded surface hardness of TC11 at the impingement angle 90° increases and then decreases, while the volume loss rate drops in the first 15 min, then increases until 30 min, and then slightly decreases again. With XRD characterization and SEM observation, erosion-induced phase transformation from metastable β-phase to α-phase is proved on the surface of titanium alloy TC11. And the thickness of visible phase transformation layer is about 10 μm. Phase transformation influences the erosive wear mechanism of titanium alloys. At the impingement angle of 30°, the material removal of TC4 and TC11 can be described as micro-plowing and lip extruding, while plowing mark is not a typical surface morphology of TA2, indicating a better work-harden ability. So, stabilizing β-phase can be an effective way to improve the erosion wear resistance of titanium alloys.     

Effect of load and speed on the wear behaviour of woven glass fabrics and aramid fibre-reinforced composites

In the present study, wear behaviour of woven 300 and 500 glass fabrics and aramid fibre-reinforced composite materials are experimentally investigated for 500 and 710 rpm speeds and at two different loads of 500 and 1000 g using a block-on-shaft wear tester. The wear in the experiments was determined as weight loss. The weight losses were measured after different sliding distance conditions. The worn surfaces were also examined by scanning electron microscope (SEM). As a result of this study, it is shown that the applied load on the specimens has more effect on the wear than the speed. Also the weight loss in the woven 500 glass fabric reinforced is more than that in the woven 300 glass fabric-reinforced composite. The weight loss of aramid fibre-reinforced composite is quite low compared with woven glass fabric-reinforced composites.     

Erosive wear of composite materials

The erosive wear behavior of selected polymer matrix composite materials was investigated using an erosion wear tester. Scanning electron microscopy was used to characterize the eroded surface. The results show that the erosive wear rates in these materials are at least an order of magnitude greater than that of low carbon steel. Of the composites tested, continuous graphite fiber-epoxy composites showed erosive wear that is typical of brittle materials (maximum wear rate when the impingement is normal to the surface), while continuous aramid fiber-epoxy and chopped graphite fiber-polyphenylene sulfide showed quasi-ductile behavior (maximum wear rate at 25°–45° impingement angle). These results are discussed in terms of the observed failure modes.     

Effect of coupling agent on abrasive wear behaviour of chopped jute fibre-reinforced polypropylene composites

In this paper, studies have been conducted to investigate the abrasive wear behaviour of jute fibre-reinforced polypropylene composites. Effect of addition of maleic anhydride-grafted polypropylene (MA-g-PP)-coupling agent by two different approach, sliding distance and load on abrasive wear performance of jute fibre-PP composites has been determined by using a SUGA abrasion tester. Use of coupling agent gives better wear resistance as compared to without the use of coupling agent. It has also been found that addition of MA-g-PP coupling agent during melt mixing gives better wear resistance as compared to the jute PP composites having MA-g-PP solution-treated jute fibres, which has been explained on the basis of highest thermal stability of jute-PP Composite having melt-mixed MA-g-PP. Abrasive wear performance of the composites has been explained with the help of surface microstructures of worn surfaces.     

Particle erosion behaviour of boiler tube materials at elevated temperature

The particle erosion behaviour of typical boiler tube materials, including carbon steel, low alloy steels and austenitic steels, at elevated temperatures up to 650 °C was studied using irregularly shaped silica particles. Using 304 steel, the influence of various factors, namely particle concentration, velocity and impingement angle, was examined. The erosion behaviour did not seem to differ significantly from that obtained at room temperature. The erosion rate was a linear function of the particle concentration. The velocity exponents obtained at 300 and 650 °C were both approximately 2.8. The peak impingement angle was at acute angles of 20° – 30°, with a tendency for the peak angle to be slightly higher at 300 °C than at 650 °C. However, the temperature effect was clearly observed in that the erosion rate at acute impingement angles increased significantly with the temperature suggesting that the steel tends to show a behaviour more typical of ductile materials as the temperature is increased. The erosion morphologies at low angles indicated cutting for every temperature used and the lengths of the cutting tracks obtained at 20° also increased with temperature.The erosion rate varied significantly between materials, e.g. the alloy (Incoloy) 800 eroded the most and the 12Cr-1Mo-V steel eroded the least at every temperature used, although every material showed an increase in the erosion rate with temperature. From an attempt to compare the erosion rate data obtained at 20° for every material at every temperature with the tensile properties of the steels, it was found that the yield strength of materials correlates reasonably well with the erosion rate. The erosion rate was apparently proportional to the reciprocal of the yield strength, suggesting that the flow stress included in Finnie's cutting theory may be conveniently substituted by the yield strength multiplied by a constant.     

Wear Performance Forecasting of Chopped Fiber–Reinforced Polymer Composites: A New Approach Using Dimensional Analysis

Solid particle erosion of polymer matrix composites is a complex process in which wear occurs from the target surface by impingement of rigid sand particles in an air medium. The rate of material removal (RMR), also referred to as the erosion rate, mainly depends on target material parameters and the erosion conditions such as impact angle, impact velocity, and erodent size. A new semi-empirical model for prediction of the erosion rate of polymer matrix composites has been developed using a dimensional analysis technique based on Buckingham's π theorem. The predictive model analytically rests upon parameters related to chopped glass fiber composites, erodent (target material properties), and operating variables that mainly affect the erosion process of chopped glass fiber–vinyl ester resin composites. The forecasting ability of the predictive model has been assessed and verified by experimental investigations for chopped glass fiber–reinforced vinyl ester resin (VGF) composites. Validation of the theoretical erosion rates obtained from the predictive model showed that they were in good agreement with the experimentally determined erosion rates, where the average error range was estimated to be ～10 to ～20%.     

Influence of impingement angle on solid particle erosion of carbon fabric reinforced polyetherimide composite

Polyetherimide (PEI) composite reinforced with plain weave carbon fabric (CF) (40% by volume) was developed and characterized for physical and mechanical properties. The erosive wear behaviour of PEI and its composite was evaluated using silica sand particles at a constant impact velocity but varying angles of impingement. It was confirmed that though all the mechanical properties of PEI improved substantially by CF reinforcement, the erosion resistance (W_R) deteriorated by a factor of almost four–six times at all angles of impingement. Both materials showed minimum wear at normal incidence (90° impingement). In spite of the fact that PEI is not a very ductile polymer (elongation to break-60%), it showed maximum wear at 15° which is a characteristic of ductile and semi-ductile mode of failure. The composite (elongation to break-1%) also showed highest wear at 30° (impingement at 15° was not studied). These phenomena were explained using scanning electron micrographs of the eroded surfaces.     

Wear Behaviour of In Situ Al/TiB<Subscript>2</Subscript> Composite: Influence of the Microstructural Instability

In this present work, the in situ Al (A380)/5 wt%TiB₂ composites were fabricated through salt–melt reaction using halide salts such as potassium hexafluorotitanate (K₂TiF₆) and potassium tetra fluoroborate (KBF₄) salts as precursors. The composites were produced at four different melt temperatures (700, 750, 800, 850 °C). The formation of particle was confirmed from XRD results. The wear behaviour of Al/5 wt% TiB₂ composite was investigated by varying the wear test parameters such as sliding temperature (25, 100, 150, 200 °C), applied load (10, 20, 30, 40 N), sliding velocity (0.4, 0.7, 1, 1.3 m/s). The microstructure of Al/5 wt% TiB₂ composite was correlated with the wear characteristics of the composites. The wear resistance of Al/5 wt% TiB₂ composite was significantly improved due to the presence of TiB₂ particle in Al matrix material. The composite produced at melt temperature 800 °C showed a higher wear resistance at applied load: 10 N, sliding temperature: 25 °C and sliding velocity: 0.7 m/s. The wear mechanism for each of the tested condition was identified from the worn surfaces using scanning electron microscopy (SEM). ANOVA test was carried out to find out significant factor for the wear resistance of composite. The checking of adequacy of experimental value for the wear behaviour of composite for different testing condition was analysed by residual plots using statistical software.     

Effect of E-Glass fibre and ply orientation on the mechanical behaviour of FRP composites used for pressure pipe

The main goals of this experimental investigation were to compare the mechanical behaviour of resins reinforced with different woven fabrics (bidirectional and quadriaxial rovings), manufactured with the classical hand lay-up process, and to find the more appropriate industrial pressure pipe. In order to realize such applications, several mechanical properties need to be evaluated. So, a focus was essentially done on the evaluation of the effect of resin and E-Glass fibre ply orientation on the mechanical properties such as tensile strength and flexural strength of the studied composite laminates. An experimental failure analysis was carried out to observe the crack paths and failure mechanisms in the investigated laminate composites. From the main results, it was found that the composites based on R500 fabrics show the best behaviour in tensile while the laminates based on RM fabrics present the best flexural properties. The quadriaxial composite laminates (QA/VE and QA/UP) with stacking sequences of [0°, +45°, 90°, ?45°] present a very ductile tensile behaviour and the highest interlaminar fracture resistance. Consequently, they can be more appropriate for the industrial pressure pipe.     

Anomalous behaviour of high velocity oblique liquid impact

It is generally believed that erosion caused by impact with liquid drops has a maximum for normal impact. However, although this is true for many situations this paper shows that there are important exceptions, particularly where high velocity impacts are involved. Single impact studies in the velocity range 250–1200 m s^?1 were made. Three examples which show anomalous behaviour are discussed, namely polymethylmethacrylate (PMMA) where mass loss is a maximum at about 15° to the normal, a glass fibre laminate where there is a greater amount of penetration and strength loss at about 20° and a coated laminate where maximum coating loss occurs at 25°. All these phenomena took place only when critical velocities were exceeded. The results demonstrate the problems of extrapolating low velocity data into those higher velocity regimes which are becoming of increasing practical importance.     

Solid particle erosion of CFRP composite with different laminate orientations

The solid particle erosion behavior of epoxy base unidirectional and multidirectional carbon fiber reinforced plastic composites was investigated. The erosion rates of these composites were evaluated at various impingement angles (15–90°) with a particle velocity of 70 m/s. Irregular SiC particles with an average diameter of 80 μm was used. The dependence of impingement angle on the erosive wear resembled the conventional ductile behavior with maximum erosion rate at 15–30° impingement angle. The erosion rate of unidirectional composites at acute impingement angle was higher for [90] than for [45] and [0] while the difference disappeared at normal impingement angle (90°). On the other hand, the erosion rates of multidirectional laminated composites ([0/90], [45/−45], [90/30/−30] and [0/60/−60]) were not much influenced by the fiber orientation except for 15° impingement angle.