Erodent size effect on the erosion of polyphenylene sulfide composite

The effect of erodent particle size on solid particle erosion of randomly oriented short glass fiber and mineral particle reinforced polyphenylene sulfide (PPS) was investigated. To examine the effect of erodent size on the erosion resistance of the PPS composite, aluminum oxide particles at three different sizes, namely, 300–425 μm, 150–212 μm, and 45–75 μm, were used. The erosion tests were performed at six different contact angles of 15°, 30°, 45°, 60°, 75°, and 90°, respectively. The results showed a strong relationship between the erodent particle size and erosion rates of PPS composite. Maximum erosion rate for the erodent particles with sizes of 45–75 μm and 150–212 μm occurred at contact angle of 30°, on the other hand maximum erosion rate for particles having 300–425 μm size occurred between 45° and 60°. The morphologies of eroded surfaces were characterized by the scanning electron microscopy (SEM). Possible erosion mechanisms were discussed. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Solid Particle Erosion of Lantana Camara Fiber-Reinforced Polymer Matrix Composite

The present investigation reports the solid particle erosion behaviour of randomly oriented short Lantana-Camara fiber-reinforced polymer composites (LCRPCs) using silica sand particles (200 ± 50 µm) as an erodent. The erosion rates of these composites have been evaluated at different impingement angles (15°–90°) and impact velocities (48 m/s–109 m/s) with constant feed rate of erodent (1.467 ± 0.02 gm/min). Highest wear rates were investigated at impingement angles 45°. Erosive wear rates were found to have a close relationship with the impingement angle of the erodent and speed. The morphology of eroded surfaces was examined by using scanning electron microscopy (SEM). Possible erosion mechanisms were discussed.     

Erosive wear behavior of spark plasma-sintered SiC–TaC composites

Spark plasma sintering of SiC-10, 20, or 30 wt% TaC composites was performed at 1800°C. Microstructures of sintered composites revealed uniform dispersion of TaC particles in SiC matrix. With the increase in TaC content, hardness decreased from 25.75 to 23.30 GPa and fracture toughness increased from 3.48 to 3.85 MPa m^1/2. Erosion testing was performed to evaluate the potential of sintered composites at room temperature and 400°C by a stream of SiC particles impinging at different angles (30°, 60°, or 90°). The erosion rate varied from 25 to 166 mm³/kg, with change in TaC content, impingement angle, or temperature. The erosion rate increased as the angle of impingement and temperature increased, but reduced when the TaC concentration increased. Worn surfaces revealed that the material was dominantly removed via fracture of SiC grains and TaC particles pull-out. SiC-30 wt% TaC composites exhibited superior erosive wear resistance at low impingement angle and room temperature.     

Solid particle erosion behaviour of high purity alumina ceramics

The solid particle erosion behaviour of a high purity, cold isostatically pressed ceramics, CIP-Al₂O₃, is studied in this paper. The influence of particle properties, such as hardness and shape, on erosion is examined, as well as the effect of varying the impingement angle of the erodent stream on the weight loss of alumina ceramics samples. Therefore, the erosive wear behaviour was studied at five different impact angles (30°, 45°, 60°, 75° and 90°), using SiC and SiO₂ particles as erodents.The material loss during solid particle erosion is measured by changes in surface roughness, surface morphology and mass loss.The surface roughness and topography of the eroded Al₂O₃ ceramics were recorded using a profilometer.Scanning electron microscopy (SEM) was used to examine the features of eroded surfaces and to ascertain erosion mechanisms of the tested alumina samples.The results indicate that hard, angular SiC particles cause more damage than softer, more rounded SiO₂ particles. It was found that maximum erosion by both types of particles occurs at an impact angle of 90°.     

Evaluation of oxy-acetylene flame angle effect on the erosion resistance of SiC/ZrB2–SiC/ZrB2 multilayer coatings fabricated by the shielding shrouded plasma spray technique

In the present study, the effect of oxy-acetylene flame angle on the erosion resistance of SiC/ZrB₂–SiC/ZrB₂ multilayer coatings with the gradient structure was investigated. To this aim, first, the SiC inner layer was applied by the reactive melt infiltration (RMI) technique; then ZrB₂ and ZrB₂–SiC layers with 10, 20 and 30%wt. SiC were applied on graphite by the plasma spraying technique. To prevent the oxidation of ZrB₂ and SiC particles, the plasma spraying process was performed by a solid protective shield. To evaluate the performance of the coatings in erosive environments, the samples were exposed to oxy-acetylene flame at the angles of 30°, 60° and 90° for 360 s; the destruction mechanism of SiC/ZrB₂–SiC/ZrB₂ multilayer coatings appeared to be controlled mechanically and chemically. The results of the erosion test showed that at the low flame angles of about 30°, due to the shear forces of oxy-acetylene flame, mechanical erosion overcame the chemical one. With increasing the flame angle, due to raising the surface temperature, chemical erosion overcame the mechanical one; so, most chemical destruction occurred at the flame angle of 90°. Also, the results of the erosion test showed that the total chemical and mechanical destruction at the angle of 60° was greater than that in other angles. Also, among the coatings tested, SiC/ZrB₂- 20% wt. SiC/ZrB₂ coatings had the best erosion resistance; so, the weight changes under the oxy-acetylene flame at the angles of 30° and 60°, respectively, were about ?0.038%. and ?0.355%; meanwhile, at the angle of 90°, it was about +4.3%.     

Tetrahedral amorphous carbon deposited with the pulsed plasma arc-discharge method as a protective coating against solid impingement erosion

The solid impingement erosion resistance of a tetrahedral amorphous carbon (ta-C) coating (sp³ bonding fraction ∼80%, thickness 20 μm) was compared to the erosion resistance of stainless steels, WC–Co hard metal, sintered SiC, sintered Al₂O₃, synthetic ruby (Al₂O₃, grain size of the order of mm) and a commercial TiN coating. The ta-C coating was deposited by the filtered pulsed plasma arc-discharge method on an AISI316L stainless steel sample. All other materials, except the ta-C and the TiN, were in a bulk form. The experiments revealed that the volume removal rate of bulk materials was 1.5–540 times higher than that of ta-C, depending on the material. The extensive chipping of TiN hindered a meaningful comparison of the measured results to those received from bulk materials. The erosion experiments were performed with a test apparatus, which used pressurized air to accelerate angular Al₂O₃ particles (60–77 μm in diameter). The erosion damage was analyzed with a surface profilometer and an optical microscope. The critical thickness for the coating that was able to resist catastrophic delamination under particle exposure, was found to be approximately 1 μm. The extremely low erosion rate of ta-C, when eroded with low values of angle of attack (∼20°), implies that ta-C erodes in a brittle manner.     

Effect of impact angle on glass surfaces eroded by sand blasting

In a previous work, we studied the effects of sand blasting on the roughness, the optical transmission and the mechanical strength of a soda lime glass for sand blasting durations up to 150 min and under a constant impact angle of 90°. In the present work, we examine the effect of impact angles (30 to 90°) for relatively small durations up to 60 min on the surface roughness and the optical transmission. The roughness increases and tends towards a plateau, while the optical transmission decreases and tends towards a threshold estimated at about 50% of the initial transmission. We noticed that the samples erosion damage becomes weaker for impact angles less than 90° (90° angle corresponds to the flux normal to the samples). Microscopic observations reveal that the damage is similar to that of sharp indentation damage type Vickers indentation. There is formation of a plastic imprint with radial cracks and some scaling caused by the development of lateral cracks that extend and curve up to the surface. From the expression of the damage rate as defined in the literature, we introduced a function relating the impact angles and the sand blasting durations to the optical transmission. The experimental data obtained seem to fit quite well to the proposed function.     

Mechanical Properties and Solid Particle Erosion Behavior of LaMgAl11O19–Al2O3 Ceramic at Room and Elevated Temperatures

In this work, the mechanical properties and solid particle erosion wear behavior of LaMgAl₁₁O₁₉–Al₂O₃ ceramics toughened and reinforced with LaMgAl₁₁O₁₉ platelets were investigated. The effects of LaMgAl₁₁O₁₉ additions, impingement angles (30°, 45°, 60°, 75°, and 90°), and erosion temperatures varying from room temperature to 1400°C on the erosion rates and material removal mechanisms of LaMgAl₁₁O₁₉–Al₂O₃ composites were systematically studied. The results indicated that LaMgAl₁₁O₁₉–Al₂O₃ ceramics exhibited superior erosive wear resistance compared to monolithic Al₂O₃ ceramics at room and elevated temperatures due to their enhanced mechanical properties and improved microstructure resulting from the introduction of an appropriate amount of LaMgAl₁₁O₁₉ platelets. Examination of the eroded surfaces of LaMgAl₁₁O₁₉–Al₂O₃ composites revealed that erosion temperatures and impingement angles play important roles in determining the erosion behavior and mechanisms of the tested materials. For the case of elevated temperature and oblique erosion, plowing and subsurface intergranular fracture are the predominant mechanisms resulting in material removal, whereas at room temperature and normal impact, the erosion process of the targets is primarily dominated by grain ejection and lateral crack intersection.     

Performance of the silicon carbide coating under erosion wear by erosion by solid particles

In this article, the phenomenon of erosion by solid particles on the silicon carbide coating (SiC) deposited on AISI 304 stainless steel substrates was analyzed. The specimens used were 25 mm square and 3 mm thick, using 300–450 μm silicon carbide as abrasive particles. Experimental tests were performed on an apparatus developed in accordance with some parameters of the ASTM G76-95 standard. Four angles of impact at 30°, 45°, 60°, and 90° are contemplated with an approximate particle velocity of 25 ± 2 m/s with a maximum exposure time of 10 min per specimen, taking measurements of weight intervals every 2 min to determine the mass loss. The wear mechanisms that were identified to small angles were: plastic deformation, displacement of material, and plow mechanisms. While at higher impact angles, the mechanisms were mainly: cutting, pitting, fractures, and cracks. It was observed that the rate of erosion depends on the angle of incidence of the abrasive particles. The results indicated that a higher damage zone was obtained at 30° of impact angle; on the other hand, at an angle of 90° there was less damage.     

Erosion Wear Behavior of TiCN–Ni Cermets Containing Secondary Carbides (WC/NbC/TaC)

The present communication reports the results of a first set of erosion wear experiments, conducted on TiCN–20 wt% Ni cermets containing different secondary carbides (WC, NbC, and TaC). The cermets are eroded by SiC particles (66 μm size) with a constant mass flow rate (2.33 g/s) at different angles of impingement (30°, 60°, 90°) on an in-house fabricated erosion wear tester. An important experimental observation is that the investigated cermets exhibit behavior similar to ceramics, as evident from the systematic increase in erosion wear rate with impact angles. Among all investigated cermets, WC-added TiCN–20 wt% Ni cermets exhibit superior erosion wear resistance. SEM investigations of eroded surfaces (normal incidence) reveal grain pullout with intergranular fracture as the dominant material removal process.     

Influence of erodent particle types on solid particle erosion of polyphenylene sulphide composite under low particle speed

The influence of erodent particle types on solid particle erosion of randomly oriented short glass fiber and mineral particle reinforced polyphenylene sulphide (PPS) was investigated. The solid particle erosion studies were carried out using low speed solid particle erosion test rig with 150 to 212‐μm brown fused aluminum oxide (Al₂O₃), 150 to 200‐μm silica sand and 150 to 250‐μm glass bead. Glass bead eroding particles appear spherical in shape whereas aluminum oxide and silica sand eroding particles have sharp and angular edges. The erosion tests were conducted at six different contact angles of 15, 30, 45, 60, 75, and 90°, respectively. The results showed a strong dependence of the eroding particle types on the erosive wear behavior of PPS composite. The peak erosion rate occurred at 45° contact angle for silica sand eroding particles while the peak erosion rate occurred at 30° contact angle for aluminum oxide and glass bead particles. The morphologies of eroded surfaces were characterized by the scanning electron microscopy. In case of aluminum oxide and silica sand, the erosive wear mechanism occurs firstly by the erosion of matrix, followed by the fracture of un‐supported fibers and their detachment; however, the erosive wear mechanism occurs different for glass bead particles. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Erosion characteristics of N720/alumina oxide/oxide ceramic matrix composites in a combustion environment

The erosion behavior of N720/Alumina oxide/oxide composite was investigated under a combustion environment to better represent particle ingestion of a jet engine. The effect of particle velocity, particle size, temperature and impingement angle were investigated. In addition, room temperature studies were also conducted for comparison. Eroded sites were investigated using optical and scanning electron microscopy to understand the extent of erosion and erosion mechanisms. The results indicate that erosion rate increased with an increase in particle velocity and particle size. Also, erosion rate increased from room temperature to 815 °C and then decreased from 815 °C to 1200 °C. Brittle fracture is the predominant mode under normal impacts and as the impact angle is decreased increased ploughing/wear is evident.     

Possible use of volcanic ash as a filler in polyphenylene sulfide composites: Thermal,mechanical, and erosive wear properties

It is a common practice to use particle materials as fillers to improve engineering properties of polymer composites and to lower the cost of final products. There is an obvious cost advantage of compounding volcanic ash (VA) in polymers, either to replace traditional fillers. This study is concerned with thermal, mechanical, and erosive properties of VA‐filled polyphenylene sulfide (PPS) composites. Composite samples containing VA particles at various concentrations (0, 2.5, 5, 10, 15, and 20 wt%) were manufactured by twin screw extruder and injection molding machine. Thermal properties were investigated by thermogravimetric and dynamic mechanical analysis methods. Erosive wear properties were investigated by performing solid particle erosion tests at 30º and 90º impingement angles. The mechanical properties such as flexural strength and modulus of uneroded samples and residual flexural strength and modulus of eroded composite samples were determined by three‐point bending tests. Results show that thermal, mechanical, and residual mechanical properties of the PPS composite were significantly improved by adding VA, although erosion resistance was decreased markedly. It was concluded that VA can be used as a reinforcement in PPS composites to improve thermal and mechanical properties and to reduce the cost of the PPS composites. POLYM. COMPOS., 35:1826–1833, 2014. © 2014 Society of Plastics Engineers     

两种不锈钢冲刷腐蚀的研究

用板状试样在料浆罐式冲刷腐蚀实验机上研究了两种不锈钢的冲刷腐蚀规律。结果表明,力学性能只在冲刷速度高时才对材料耐冲刷腐蚀性有显著作用,在冲刷速度高时,２Ｃｒ１３的冲刷腐蚀失重比１Ｃｒ１７Ｍｏ２低;而在冲刷速度低时（２ｍ／ｓ）,１Ｃｒ１７Ｍｏ２的冲刷腐蚀失重比２Ｃｒ１３的低。材料的力学性能也影响其在不同冲刷角度时的冲刷腐蚀规律。２Ｃｒ１３的冲刷腐蚀失重随冲刷角度增大而单调增加,在冲刷角为９０°时最大。１Ｃｒ１７Ｍｏ２的冲刷腐蚀失重在３０°左右时出现峰值,在９０°时为最大。两种材料的纯冲刷失重随冲刷角度的变化与冲刷腐蚀失重的变化类似。     

Structural and mechanical properties of needle‐punched nonwoven reinforced composites in erosive environment

Polypropylene‐based needle‐punched nonwoven reinforced epoxy composites have been fabricated and were evaluated for their thermomechanical response and dry erosion performance. The erosive wear investigations were carried out using silica sand particles as erodent with varying impact velocity, angles of impingement, fiber content, and stand‐off‐distance as the operating variables. Design of experiments (DoE) approach‐based Taguchi analysis was carried out to establish the interdependence of operating parameters and erosion rate. Impingement angle and impact velocity have been found to be the most significant determinants of erosive wear performance of such nonwoven reinforced composites. The composites were also observed to be appreciably resistant to impact content and indentations in addition to exhibiting the absence of any storage‐modulus decay till 60°C accompanied with a nominal increase in the primary transition temperature as revealed from loss‐tangent peaks. The composite with 30 wt % and 40 wt % of nonwoven materials have shown the highest and lowest erosion rates, respectively. The morphology of eroded surfaces was examined by using scanning electron microscopy (SEM) and their possible erosion mechanisms are discussed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Influence of the die entry angle on the entrance pressure drop,recoverable elastic energy,and onset of flow instability in polymer melt flow

An experimental study has been carried out to investigate the effects of die entry angle on the entrance pressure drop, recoverable elastic energy, and onset of melt fracture in the flow of viscoelastic polymeric melts through a capillary die. For the study, capillaries with an L/D ratio of 4 and with varying die entry angles, 15°, 30°, 60°, 90°, 120°, and 180°, were used for extruding low-density polyethylene and high-density polyethylene. Measurements were taken of wall normal stresses along the upstream reservoir section, tapered conical section, and straight capillary section.     

Influence of angle deposition on the properties of ZnTe thin films prepared by thermal evaporation

Thin films of ZnTe were deposited at angles of 0°, 20°, 40°, 60° and 80° by thermal evaporation. The chemical, structural, morphological, optical, and photocurrent properties of ZnTe thin films were investigated. The elemental composition of the films was investigated by energy dispersive x-ray spectroscopy (EDX) and x-ray photoelectron spectroscopy (XPS). EDX and XPS analyses showed that at lower angles (0° and 20°), the deposited films were Te-rich, at 40°, the deposited film was nearly stoichiometric; and at higher angles (60° and 80°), the deposited films were Zn-rich. X-ray diffraction (XRD) analysis showed that all films were polycrystalline. X-ray diffraction patterns showed that lower-angles-deposited films had an extra peak at 2θ =?36.47° that belongs to Te element. Atomic force microscopy analysis revealed that the surface roughness of films was increased by increasing the deposition angle from 0° to 80° because shadowing effect raised due to an oblique angle. It was observed that higher-angles-deposited films (ZnTe-60°, and ZnTe-80°) showed less transmittance and high reflectance compared to lower-angles-deposited films because of high metallic Zn content in these films. Current-voltage (I-V) measurements showed that nearly stoichiometric (ZnTe-40°) film showed better photocurrent response compared to non-stoichiometric films (ZnTe-0°, ZnTe-20°, ZnTe-60°, and ZnTe-80°).     

Effect of fiber loading and orientation on mechanical and erosion wear behaviors of glass–epoxy composites

For a composite material, its mechanical behavior and surface damage by solid particle erosion depend on many factors. One of the most important factors is the fiber content. Similarly, these properties are also greatly affected by the fiber orientation. In this work, a series of experiments were carried out to investigate the influence of fiber loading and fiber orientation on mechanical and erosion behavior of glass fiber‐reinforced epoxy composites. The composites were fabricated with three different fiber loadings (20, 30, and 40 wt%) and at four different fiber orientations (15°, 30°, 45°, and 60°). The conclusions drawn on the basis of the experimental findings are discussed, and composite with 30° fiber orientation shows better microhardness compared with other fiber orientations irrespective of fiber loading. Similar observations are also noticed for other mechanical properties of the composites, such as tensile strength, flexural strength, interlaminar shear strength, impact strength, etc. Finally, the morphology of eroded surfaces is examined using scanning electron microscopy (SEM), and possible erosion mechanisms are identified. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Uncertainty in contact angle measurements from the tangent method

The uncertainty in contact angles from sessile drops measured by the tangent method was estimated using a standard error propagation technique involving partial derivatives. If contact angles are <60°, then uncertainty of the tangent method appears to be quite small,≤ ± 2°. However, as θ values approach 90°, uncertainty increases asymptotically and can exceed ±5°.     

The effect of carbon nanotube orientation on erosive wear resistance of CNT-epoxy based composites

Aligned carbon nanotube (CNT) polymer composites are envisioned as the next-generation composite materials for a wide range of applications. In this work, we investigate the erosive wear behavior of epoxy matrix composites reinforced with both randomly dispersed and aligned carbon nanotube (CNT) arrays. The aligned CNT composites are prepared in two different configurations, where the sidewalls and ends of nanotubes are exposed to the composite surface. Results have shown that the composite with vertically aligned CNT-arrays exhibits superior erosive wear resistance compared to any of the other types of composites, and the erosion rate reaches a similar performance level to that of carbon steel at 20° impingement angle. The erosive wear mechanism of this type of composite, at various impingement angles, is studied by Scanning Electron Microscopy (SEM). We report that the erosive wear performance shows strong dependence on the alignment geometries of CNTs within the epoxy matrix under identical nanotube loading fractions. Correlations between the eroded surface roughness and the erosion rates of the CNT composites are studied by surface profilometry. This work demonstrates methods to fabricate CNT based polymer composites with high loading fractions of the filler, alignment control of nanotubes and optimized erosive wear properties.