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.     

Impact of stacking sequence on tribological wear performance of woven jute-glass hybrid epoxy composites

Natural fibre-reinforced plastic (FRP) composites have gained much interest because of their environment friendliness and cost-effectiveness compared to synthetic fibre-reinforced composites. The availability of natural fibre and ease of manufacturing have tempted researchers worldwide to develop a locally available low-cost fibre and study their feasibility for reinforcement purposes and to what extent they can satisfy the required specifications of well-reinforced polymer composite for tribological application. FRP composites have various applications in the automobile, aerospace and marine fields. They are applied to inlet cone, fan exit guide vanes and other parts of structures in a turbofan engine for lightening an engine. The erosion characteristics of the FRP composites are of vital importance due to the operational requirements in dusty environments. In this present work, the impact of stacking sequence on erosion wear behaviour of untreated woven jute and glass fabric-reinforced epoxy hybrid composites has been investigated experimentally. The orientation of glass and jute fabric was kept at (0°–90°) and (45°–45°) for all stacking sequences. All the laminates were prepared using four plies, and, the number and position of glass layers were varied so as to obtain four different stacking sequences. The erosion rate of these composites were evaluated at different impingement angles (30°–90°) at three different impact velocities (V = 48, 70, 82 m/s). Silica sand was used as the erodent. Our results showed that the impingement angle had a significant influence on the erosion rate. The composite materials showed semi-ductile behaviour with the maximum erosion at an impingement angle of 60°. The morphologies of the eroded surface were observed by a scanning electron microscope, and the possible erosion 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.     

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 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.     

Effect of microstructure on the erosion of steel by solid particles

The effect of microstructure on the erosion of AISI-SAE 1078 and 10105 steels by 240 grit A1₂O₃ particles was investigated at particle velocities V of 40–100 m s^?1 and angles of impingement a of 10°–90° relative to the target surface. The microstructures investigated included spheroidite, pearlite, martensite and tempered martensite.Spheroidite and pearlite microstructures eroded by the ductile mode at all velocities, exhibiting a maximum erosion rate at an impingement angle of 40°. The effect of the angle of impingement on the erosion rate of martensite and tempered martensite varied with particle velocity, the erosion mode tending towards a brittle mode with increasing velocity. At all angles of impingement the erosion rate tended to increase with the volume fraction of Fe₃C. Examination of the eroded surfaces by scanning electron microscopy showed the occurrence of localized plastic flow of appreciable magnitude. No subsurface cracking or void formation was evident. The erosion rate E_r could be considered to vary with particle velocity according to the power law E_r = kVⁿ where n has a value of about 2 independent of the microstructure and the angle of impact.     

Influence of fiber orientation on abrasive wear of unidirectionally reinforced carbon fiber–polyetherimide composites

A composite with continuous carbon fibers (CF) (80% by vol.) and high performance thermoplastic polyetherimide (PEI) matrix was developed and evaluated for various mechanical properties as a function of fiber orientation angle (0°, 30°, 45°, 60° and 90°). It was observed that Young's modulus, Poisson's ratio, toughness and % strain decreased with the increase of fiber orientation angle with respect to loading direction. In-plane shear modulus was highest for fibers with 45°. Overall, unidirectional (UD) CF reinforcement enhanced all strength properties of PEI significantly. Composites with fibers in 0° (parallel to loading direction) proved best in almost all the properties. Tribological evaluation in abrasive wear mode under different loads and fiber orientations indicated that coefficient of friction (μ) and specific wear rate (K₀) decreased with load, in general. Comparatively low specific wear rate (K₀), (in the order of 0.7 1×10^?9 m³/Nm) was observed for 0° fiber orientation, while fibers in 90° showed almost three times higher wear rate. Overall fiber reinforcement in 0° orientations proved beneficial from both strength and tribological performance point of view. SEM proved useful to correlate wear rate with surface topography.     

Effect of carbide volume fraction on erosive wear behaviour of hardfacing cast irons

The present work reports the effect of carbide volume fraction on erosive wear behaviour of hardfacing cast irons. Five different grades of weld hardfacing cast irons were selected for the present investigation. The solid particle erosion experiments were carried out with blast furnace sinter, silica sand and alumina particles under mild (53–75 μm, 25 m s⁻¹), moderately severe (125–150 μm/100–150 μm, 50 m s⁻¹) and under severe erosion conditions (300–425 μm, 90 m s⁻¹) at impingement angles of 30 and 90°. The variation in erosion rate with carbide volume fraction was observed to be strong function of the erodent particle hardness, impingement angle and the impact velocity. Under mild erosion conditions, erosion rate decreased with increasing carbide volume fraction (CVF), whereas erosion rate increased with CVF under moderately severe erosion condition with alumina particles. With silica sand particles under moderately severe erosion conditions the beneficial effect of large volume fraction of carbides could only be observed at 30°, whereas at normal impact erosion rate increased with increasing CVF. The erosion rate showed power law relationship with ratio of hardness of erodent particle to that of the target material (H_e/H_t) and expressed as E=c(H_e/H_t)^p.With increasing severity of erosion conditions erosion rate showed stronger dependence on H_e/H_t as compared to those under mild and moderately severe erosion conditions. The mechanism of materials removal from the carbides involved Hertzian fracture with softer sinter particles, whereas harder alumina particles could plastically indent and cause gross fracture of the carbides.     

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.     

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.     

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.     

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.     

A study on erosion of upper bainitic ADI and PDI

Ductile iron containing ∼3.5 wt.% C and 2.1–4.2 wt.% Si (2.1, 2.8 and 4.2 wt.%) was studied. Three sets of specimens with differing Si contents were made into austempered ductile iron (ADI) and pearlite ductile iron (PDI) through heat treatment. These specimens were then eroded with Al₂O₃ particles and SiO₂ particles of 275–295 μm grit size to understand the relationship between erosion rate and microstructure. The ADI specimens were upper bainitic matrices that were austempered for different periods of time at 420 °C. The heat treatment of PDI was conducted at 870 or 930 °C for 1 h then forced air cooled or oil quenched to room temperature.Two types of wear curves, single peak curves and double peak curves, were found when plotting the erosion rate figures derived from the experimental results. 2.1 wt.% Si and 2.8 wt.% Si ADI tempered for a long period of time, due to their decreased retained austenite content and increased carbide content, had a single peak erosion rate curve. This embrittlement effect caused the impact angle of maximum erosion rate to increase from ∼30 to ∼45°. Decreasing the interspacing of the lamellae cementite promoted the hardness and improved the low-angle erosion wear resistance of PDI. The high hardness and brittleness of the matrix reduces the high-angle erosion resistance and the peak erosion rate occurs at a higher angle.For 2.1Si-ADI and 2.8Si-ADI tempered for a short duration, increasing the volume fraction of martensite in the matrix increases the erosion rate at an impact angle of 30°, but the maximum erosion rate is found at 75°. This results in a curve with a double peak. The double peak curve was also observed for high silicon ADI tempered for a long duration. The high solid solution hardness of 4.2Si-ADI, due to low retained austenite content and the presence of carbide in the matrix, results in poor erosion resistance. When this material is austempered for a long period, the erosion rate curve shifts from a single peak curve (30°) to a double peak curve (30°; 60°).     

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.     

Determination of particle impacts and impact energy in the erosion of X65 carbon steel using acoustic emission technique

An in-situ acoustic emission (AE) monitoring technique has been implemented in a submerged jet impingement (SIJ) system in an effort to investigate the effect of sand particle impact on the degradation mechanism of X65 carbon steel pipeline material in erosion conditions.A detailed analysis of the acoustic events' count rate enabled the number of impacts per second to be quantified for a range of flow velocities (7, 10, 15 m/s) and solid loadings (0, 50, 200, 500 mg/L) in a nitrogen-saturated solution at 50 °C. The number of impacts obtained from acoustic signals showed a strong agreement with theoretical prediction for flow velocities 7 and 10 m/s. A deviation between practical readings and theory is observed for flow velocity of 15 m/s which may be due to error from detected emissions of multiple rebounded particles.Computational fluid dynamics (CFD) was used in conjunction with particle tracking to model the impingement system and predict the velocity and impact angle distribution on the surface of the sample. Data was used to predict the kinetic energy of the impacts and was correlated with the measured AE energy and material loss from gravimetric analysis. The results demonstrate that AE is a useful technique for quantifying and predicting the erosion damage of X65 pipeline material in an erosion–corrosion environment.     

Influence of solid lubricants and fibre reinforcement on wear behaviour of polyethersulphone

Polyethersulphone (PES), is an amorphous, brittle and high temperature engineering thermoplastic. Two composites of PES containing short glass fibres (GF) and solid lubricants viz. PTFE and MoS₂; and two composites containing short carbon fibre (CF) [30% and 40%] were selected for the present studies. Compositional analysis of selected materials was done with various techniques such as gravimetry, solvent extraction and thermal analysis viz. thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). These materials were studied for adhesive and abrasive wear performance by sliding against a mild steel disc and silicon carbide abrasive paper respectively, under different loads. It was observed that GF reinforcement along with incorporation of solid lubricants (PTFE and MoS₂) enhanced the wear performance of PES by an order of two. In the case of solid lubricants, PTFE proved to be more beneficial than MoS₂. CF reinforcement, however, proved to be the most effective in enhancing wear performance of PES. PES reinforced with 40% CF exhibited a specific wear rate in the order of 10⁻¹⁶m³/Nm which is considered to be very good for the thermoplastic composite. In the case of abrasive wear behaviour, however, incorporation of fibres or solid lubricants deteriorated the performance of the neat matrix. SEM was employed to investigate the wear mechanisms.     

Erosive smoothing of abrasive slurry-jet micro-machined channels in glass,PMMA, and sintered ceramics: Experiments and roughness model

Abrasive slurry jet micro-machining (ASJM) was used to machine channels in glass, PMMA, zirconium tin titanate, and aluminum nitride. The channel roughness was measured as a function of the ASJM process parameters particle size, dose, impact velocity, and impact angle. The steady-state roughness of the channels was reached relatively quickly for typical ASJM abrasive flow rates. The roughness of channels having depth-to-width aspect ratios up to about 0.25 could be reduced by approximately 35% compared to the roughest channel by decreasing particle impact velocity and angle. However, machining at such conditions reduced the specific erosion rate by 64% on average. It was therefore quicker to post-blast reference channels (225 nm average root mean square (R_rms) roughness) using process parameters selected for peak removal. It was also found that the roughness of reference channels could be reduced by about 78% by post-blasting using 3 μm diameter silicon carbide particles at 15° jet incidence. The smoothest post-blasted channels had an R_rms roughness of about 23 nm in glass, PMMA, and zirconium tin titanate, and 170 nm in aluminum nitride. Computational fluid dynamics was used to predict the particle impact conditions that were used in a model to predict the steady-state roughness due to ductile erosion with an average error of 12%.     

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.     

Studies on erosion behaviour of plasma sprayed coatings on a Ni-based superalloy

In the present investigation NiCrAlY, Ni-20Cr and Ni₃Al metallic coatings were deposited on a Ni-based superalloy (18.5Fe-19Cr-0.15Cu-0.5Al-3.05Mo-0.18Mn-0.9Ti-0.18S-0.04C-5.13 (Ta + Cb)-balance Ni). NiCrAlY was used as bond coat in all the cases. Erosion studies were conducted on uncoated as well as plasma spray coated superalloy specimens at room temperature. The erosion experiments were carried out using an air-jet erosion test rig at a velocity of 40 m/s and impingement angles of 30 and 90°. Silica sand particles of size ranging between 150 and 212 μm were used as erodent. The coatings have been characterised by scanning electron microscope (SEM), optical microscope, microhardness tester and X-ray diffractometer (XRD). Scanning electron microscope (SEM), equipped with an energy dispersive X-ray analyser (EDAX) was used to analyse the eroded surfaces. Possible erosion mechanisms are discussed. The phases revealed by XRD of the coatings have shown the formation of solid solutions. Out of the three plasma sprayed coatings, the Ni₃Al coating gave the lowest erosion rate regardless of the impact angle, and the Ni-20Cr coating gave the highest erosion rate.