Dry Sand Rubber Wheel Research Articles

Comparison of some laboratory wear tests and field wear in slurry pumps

A number of different laboratory wear tests have been undertaken to measure the wear resistance of a natural rubber and a eutectic and hypereutectic white iron under abrasion and erosion conditions. Laboratory work included two different slurry jet erosion tests, a Coriolis test and an ASTM dry sand rubber wheel test.The laboratory results were compared with wear of the same materials in a centrifugal slurry pump application in a mineral processing plant. The pump application has been monitored for over 2 years and over 40 parts run to destruction. Analysis of the wear data shows a factor of almost 3 difference in wear rate between the rubber and the best white iron. Coefficient of variance of the data was in line with typical wear results from the field.The laboratory wear tests were conducted with a silica sand slurry and average particle size range of 300–500μm to match the field conditions. The Coriolis and one of the jet erosion tests showed order of magnitude similarity with the field test results for the metals, but the other tests gave very different trends. The jet and Coriolis erosion tests on the rubber showed a much lower wear rate than seen in the field, while the DSRW test found that the eutectic white iron wear rate was lower than that of the hypereutectic iron (all opposite of the field test).Explanation for the different wear rates between the laboratory and field tests was postulated to be non-representative wear mechanisms. This is compounded by the lack of understanding of specific wear conditions in the pump (local velocity, concentration, particle size, size distribution and particle shape) as well as microstructure of the samples.

Three-body abrasive wear behaviour of aluminium alloys

Investigations were carried out on three-body abrasive wear behaviour on six aluminium alloys (AA1050, AA2014-T6, AA3003, AA5052, AA6061-T6 and AA6351-T6). Evaluation and comparison of the abrasion resistance of the aluminium alloys were carried out using silica sand of size 150-250 µm by dry sand rubber wheel (DSRW) test rig at room temperature. The tests were performed at constant rubber wheel sliding velocity ( V = 2.4 m/s) at different loads (5-20 N). Abrasion studies reveal that abrasive wear increases with increase in load. The wear volume was found to be in linear relationship with sliding distance and the steady state behaviour of the materials was attained around a sliding distance of 5760 m. Correlation of abrasive wear rate with hardness, ultimate strength and percentage elongation at break are reported. Wear mechanisms involved in material removal process were studied with the aid of optical microscope and scanning electron microscope (SEM).

Design of newly fabricated tribological machine for wear and frictional experiments under dry/wet condition

Nowadays, there is demand to evaluate tribological performance of new engineering materials using different techniques. Various laboratory tribo-machines have been designed and fabricated such as Pin-on-Disc (POD), ASTM G99, Block-on-Ring (BOR), ASTM G77 or G137-953, Dry Sand Rubber Wheel (DSRW), ASTM G655, Wet Sand Rubber Wheel (WSRW), ASTM G105, and sand/steel wheel test under wet/dry conditions (ASTM B611). A concept of integrating more than one tribo-technique at different contact mechanisms (line or area) working simultaneously under same test condition against same material is introduced in a current designed machine. Different wear modes (adhesive, two-body-abrasive, three-body-abrasive, under dry, lubricated, or slurry conditions) can be conducted on the same machine. Results of adhesive wear, friction and interface temperature of glass fibre reinforced polyester composite under wet/dry contact condition are reported at 50N load for different sliding speeds (2.8–7.8m/s) using the new machine. Weight loss and friction coefficient of the composite were substantially influenced by introducing water as lubricant. Additionally, the contact condition has the high influence key on the wear and frictional performance of the composite.

Investigating the influence of sand particle properties on abrasive wear behaviour

Abrasion by sand particles is an important factor causing excessive wear in machines operating in sandy environments. To prevent such machines from failing, knowledge about the abrasive wear process is required. This work focuses on the relation between abrasive particle properties and the wear they cause.Sand was taken from several locations around the world, with variations in particle size and shape. The wear of DIN St-52 steel samples caused by the particles was investigated by performing dry sand–rubber wheel tests with the varieties of sand. The sand particles were sieved to determine their size range. The particle shape was characterised by making images with a confocal microscope and calculating shape factors. The experimental results show significant differences in wear caused by the sand varieties tested. Traditionally used characterisation parameters like size and shape factor, however, cannot explain these differences. There appears to be a relation between the amount of wear and a combination of the particle properties tested.

Comparison of abrasive wear of a complex high alloy hardfacing deposit and WC–Ni based metal matrix composite

The abrasive wear of hardfacing deposits of a complex high alloy (SHS9290) and a tungsten carbide–Ni based metal matrix composite (MMC) has been compared using silica, garnet and alumina grit. In dry sand rubber wheel tests with silica abrasive and pin-on-flat tests with garnet abrasive, the SHS9290 alloy has shown a lower wear rate than the WC–Ni MMC. In comparison, in pin-on-flat tests using alumina abrasive, a higher wear rate was measured for SHS9290 alloy than the WC–Ni based MMC. The wear data has been interpreted in terms of the hardness of the constituent phases relative to the abrasives. The combination of high resistance to abrasive wear and known fracture toughness of SHS9290 alloy are optimal properties for digging picks used in ore excavation except with minerals of extreme hardness.

An Experimental Study on the Effect of Microstructure on Wear Behavior of Fe-Cr-C Hardfacing Alloys

Hardfacing is a low cost method of depositing wear resistant surfaces on metal components to extend service life. The prime requirement of a metal is to have good resistance to wear, corrosion and high temperature. A study has been carried out to investigate the relationship between abrasive wear resistance and microstructure of Fe-Cr-C hardfacing alloy. Two different commercial hardfacing electrodes were employed to investigate the effect of the microstructure. Results indicate that as hardness increases, the loss of wear decreases. Electrode-I has less wear as compared to electrode-II as the percentage of chromium, carbon and silicon is more in electrode-I. The abrasion tests were carried out in a dry sand-rubber wheel abrasion machine according to the procedure A of ASTM G65 standard. The factors such as, arc current, arc voltage, welding speed, electrode stick-out and preheat temperature, predominantly influence the weld quality.

Multiple Response Optimization of Three-Body Abrasive Wear Behaviour of Graphite Filled Carbon-Epoxy ComPosites Using Grey-Based Taguchi Approach

The three-body abrasive wear behaviour of carbon fabric reinforced epoxy (C-E) composites has been evaluated by the addition of graphite (G) particles as a secondary reinforcement. Three-body abrasive wear test were conducted using dry sand rubber wheel abrasion tester as per ASTM G-65 with three process parameters load, abrading distance and filler content. To assess the abrasive wear behaviour of particulate filled C-E composites satisfying multiple performance measure, grey-based Taguchi approach has been adopted. The experiments were designed according to Taguchi’s orthogonal array (L¬27). The grey relational analysis was applied to convert a multi response process optimization to a single response. Using analysis of variance, significant contributions of process parameters have been determined. The results indicate that the addition of graphite particles into C-E composite increased the wear resistance considerably. It was observed that highest wear resistance of C-E composite was achieved with incorporation of 10 wt. % of graphite filler. Results indicate that the filler content and grit size of abrasive paper were found to be the most significant factor which has influence on the abrasive wear of C-E composite. The worn surface features were examined through scanning electron microscope to probe the wear mechanism.

Effect of cerium on abrasive wear behaviour of hardfacing alloy

Hardfacing alloys with different amounts of ceria were prepared by self-shielded flux cored arc welding. The abrasion tests were carried out using the dry sand-rubber wheel machine according to JB/T 7705-1995 standard. The hardness of hardfacing deposits was measured by means of HR-150AL Rockwell hardness test and the fracture toughness was measured by the indentation method. Microstructure characterization and surface analysis were made using optical microscopy, scanning electron microscopy (SEM) and energy spectrum analysis. The results showed that the wear resistance was determined by the size and distribution of the carbides, as well as by the matrix microstructure. The main wear mechanisms observed at the surfaces included micro-cutting and micro-ploughing of the matrix. The addition of ceria improved the hardness and fracture toughness of hardfacing deposits, which would increase the resistance to plastic deformation and scratch, thus the wear resistance of hardfacing alloys was improved.

Three-Body Abrasive Wear Behavior of Basalt and Glass Fabric Reinforced Epoxy Composites

Three-body abrasive wear behavior of basalt–epoxy (B–E) and glass–epoxy (G–E) composites have been investigated using Dry sand rubber wheel abrasion resistance for various abrading distance, viz., 150, 300, 450 and 600m and different loads(22N and 32N) at 200 rpm. The weight loss and specific wear rate as a function of load and abrading distance were determined. The weight loss increases with increasing load and also with abrading distance while the specific wear rate decreases with increase in abrading distance and increases with the load. Better abrasion wear resistance was observed in B-E composite compared to G–E composite. Scanning Electron Microscope (SEM) is used to examine the abraded composite specimens and revealed that the more damage occur to glass fiber compared to basalt fiber. Also good interfacial adhesion was observed between epoxy and basalt fiber which leads to good abrasive wear resistance.

Comparative Abrasive Wear Study of HVOF Coatings Obtained by Spraying WC-17Co Microcrystalline and Duplex Near-Nanocrystalline Cermet Powders

High velocity oxy-fuel spraying was used to develop a near-nanocrystalline coating from a duplex Co coated WC-17Co powder feedstock. A microstructural and mechanical property characterization of the coating with a similar microcrystalline coating of the same composition was made. X-ray diffraction analysis showed less decarburization of the nanocrystalline coating and a more homogeneous coating structure than the microcrystalline coating produced under the same spraying conditions. The mechanical assessment of the coatings was performed using microhardness and indentation fracture toughness measurements. The abrasive wear resistance was determined using the ASTM G65-04 dry-sand rubber wheel test. The results showed that the hardness of the near-nanocrystalline coating was 25% greater than that of the microcrystalline coating and a sixfold increase in the abrasive wear resistance was also recorded for the near-nanocrystalline coating. Examination of the worn surfaces using atomic force microscopy after abrasive testing showed a smoother surface roughness in the near-nanocrystalline coating than that of the microcrystalline coating surface. The increase in fracture toughness of the near-nanocrystalline coating prevented brittle fracture of the coating surface.

Abrasive wear behaviour of conventional and large-particle tungsten carbide-based cermet coatings as a function of abrasive size and type

Abrasive wear behaviour of materials can be assessed using a wide variety of testing methods, and the relative performance of materials will tend to depend upon the testing procedure employed. In this work, two cermet type coatings have been examined, namely (i) a conventional tungsten carbide-cobalt thermally sprayed coating with a carbide size of between ∼0.3–5 μm and (ii) a tungsten carbide-nickel alloy weld overlay with large spherical carbides of the order of ∼50–140 μm in diameter (DuraStell). The wear behaviour of these two materials has been examined by the use of two abrasion tests, namely the micro-scale abrasion test using both silica and alumina abrasives (typically 2-10 μm in size), and the dry sand-rubber wheel test (ASTM G65), again with both silica and alumina abrasives (typically 180–300 μm in size). It was found that when the abrasive particles were of the same scale or larger than the mean free path between the hard phase particles, then the matrix phase was well protected by the hard phases. Testing (in both test types) with alumina abrasives resulted in wear of both the hard carbide phases and the matrix phases in both the thermally sprayed coating and the weld overlay, with the thermally sprayed coating exhibiting lower wear rates. The wear behaviour of the materials with the more industrially relevant silica abrasive was more complex; the thermally sprayed coating exhibited a lower wear rate than the weld overlay with the fine abrasive in the micro-scale abrasion test due to effective shielding of the matrix from abrasive action due to the fine reinforcement particle size. In contrast, with the coarser silica abrasive in the dry sand-rubber wheel test, the weld overlay with the large carbides was able to provide matrix protection with low rates of wear, whereas the thermally sprayed coating wore by fracture of the more brittle microstructure. These findings demonstrate the importance of selection of appropriate laboratory test procedures and abrasives to simulate behaviour of materials in service environments.

Abrasive wear behaviour of hard powders filled glass fabric–epoxy hybrid composites

The effect of incorporation of tungsten carbide (WC) and tantalum niobium carbide (Ta/NbC) powders on three-body abrasive wear behaviour in glass fabric–epoxy (G–E) composites was investigated and findings are analysed. A vacuum assisted resin transfer moulding (VARTM) technique was employed to obtain a series of G–E composites containing different fillers (WC and WC + Ta/NbC). Dry sand rubber wheel abrasion test was carried out at 200 rpm speed. The effect of different loads (22 and 32 N) and abrading distances (from 135 to 540 m) on the performance of the wear resistance were measured. The wear volume loss of the composites was found increasing with the increase in abrading distances and under the same conditions the specific wear rate decreases. The hard powders filled G–E composite systems exhibit lower wear volume loss and lower specific wear rate as compared to unfilled G–E composite system. The features of worn surfaces of the specimen were evaluated at higher and lower abrading distances at load of 32 N were using scanning electron microscope (SEM) and results indicate more severe damage to matrix and glass fiber in unfilled composite system as compared to hard powder filled composites.

Wear behaviour of hypereutectic Al–Si–Cu–Mg casting alloys with variable Mg contents

The wear properties of A390 (Al–17Si–4.5Cu–0.5Mg, wt%) hypereutectic Al–Si alloy were compared to new alloys containing 6 and 10 wt% Mg. The wear behaviour was investigated using dry sand rubber wheel (DSRW) abrasive wear apparatus for these alloys in the as-cast condition and after T6 heat treatment. A transformation of hard and coarse primary Si particles to fine Mg2Si particles with inferior hardness occurs with increasing Mg content. The finer particle size together with increasing solid fraction of the primary phase was found to be key factors in improving the wear resistance of alloys with high Mg content. In addition, the eutectic matrix microstructure of alloys with high Mg content showed considerable changes, particularly in size and morphology of the eutectic silicon which significantly contributes to the wear resistance. The wear test results showed improved wear resistance for alloys with high Mg content. The microstructure of the worn surface indicated that the intermetallic Mg2Si particles in alloys with 6% and 10% Mg addition are more solidly bonded to the matrix compared to the coarse primary silicon particles in A390 alloy which can be pulled out from the matrix. The worn surface of the A390 alloy exhibits deep and non-uniform grooves contrary to shallow and uniform grooves for the high Mg content alloys, resulting in the improved resistance to wear. Although the T6 heat treatment improved the wear behaviour of each alloy, the ranking of the wear property remained the same as the as-cast alloys.

Abrasive wear behavior of detonation sprayed WC–12Co coatings: Influence of decarburization and abrasive characteristics

The major objective of the present work is to evaluate the influence of decarburization of the WC–12Co coatings and also the abrasive characteristics on its abrasive wear behavior using a planned set of dry sand rubber wheel abrasion tests. Towards this purpose, detonation sprayed coatings have been deposited at three levels of oxygen to fuel ratios so as to obtain WC–12Co coatings with decarburization lying in the wide range of 4.4–45%. Additionally, to study the interrelationship between the abrasive characteristics and decarburization on abrasive wear, the abrasive wear tests have been conducted on WC–12Co coatings using three abrasives, i.e. SiO 2, Al 2O 3 and SiC. The results indicate that WC–12Co coatings with the decarburization levels of 4.4 and 34% results in similar abrasion rates irrespective of the type of abrasive used. However, WC–12Co coatings with a decarburization of 45% exhibited high abrasion rate and the observed increase in wear rate was also associated with a change in abrasion mechanism from one dominated by WC cuboid pullout to that of inter-splat cracking induced delamination. The wear induced subsurface damage has also been investigated.

Effect of microstructure on abrasive wear behavior of thermally sprayed WC–10Co–4Cr coatings

Thermally sprayed WC–Co coatings have been widely used in the coatings industry for its superior sliding, abrasive and erosive wear properties. In applications where corrosion resistance is also required in addition to wear resistance, WC–10Co–4Cr is the preferred coating composition. The coatings produced by different thermal spray processes exhibit a broad range of coating hardness, porosity and microstructural features like grain size and volume fraction of individual phases. In this study, we have evaluated the coating microstructures of various WC–10Co–4Cr coatings produced from different spraying processes, such as high velocity oxy-fuel (HVOF) and pulsed combustion. The objective of our study is to explore the abrasive wear mechanism of WC–10Co–4Cr coatings in great detail, and determine how these mechanisms are influenced by the coating microstructure. Dry sand rubber wheel abrasion test rig (based on ASTM G65) is used for evaluating the three-body abrasive wear properties of the coatings, using alumina as the abrasive material. The coating microstructural parameters including WC grain size, volume fraction, binder mean free path have been quantitatively measured, and correlation between abrasive wear behavior of coatings and its microstructural parameters is sought. This study shows that binder mean free path of carbides (which is a function of WC grain size and volume fraction) is a very important parameter affecting the abrasion resistance of good quality coatings (containing low porosity). The lower the binder mean free path, the higher is the abrasive wear resistance offered by the coating. This is because the abrasive wear mechanism of these coatings is dominated by preferential removal of the binder phase, followed by pullout of WC grains.

Particle motion and modes of wear in the dry sand–rubber wheel abrasion test

In the dry sand–rubber wheel test, the particles are free to move between the wheel and testpiece. The particles may either roll as they pass through the contact, or they may temporarily embed in the rubber wheel and groove the sample; the motion of the particles will govern the modes of deformation of the sample and thus the dominant mechanisms of wear. In experiments concerning the abrasion of a range of steels with widely varying hardnesses, it has been shown that the motion of the particles through the contact depends not only upon the details of the testing conditions (for example particle feedrate, particle size and shape, applied load) but also upon the testpiece material properties themselves, such as hardness. Such a dependence upon testpiece material properties is a cause for concern for those who use the test, and indicates that observations of the mechanisms of wear are an essential part of this test methodology. Particle rolling through the contact is favoured by low applied loads and low testpiece hardness whereas particle sliding through the contact is favoured by high applied loads and high testpiece hardness. The wear coefficients in situations where particle sliding (grooving) occurs are not significantly higher than those for situations where particle rolling occurs and it is argued that this is associated with the way in which grooving particles orient themselves with respect to the testpiece as they pass through the contact. This is in contrast to fixed-particle grooving abrasion (such as might be observed in tests using abrasive papers), and as such, it is argued that what is commonly termed two-body abrasion should be subcategorised into “fixed-particle grooving abrasion” and “free-particle grooving abrasion”. The paper then proceeds to provide an analysis of the motion of particles in the dry sand-rubber wheel abrasion test, and seeks to understand the mechanics controlling their motion, and thus the dependence of particle motion upon external factors, focussing on the effects of testpiece hardness and applied load. The effect of hardness on particle rotation is well predicted by the model, but the effect of the applied load on particle motion observed experimentally is opposite to that which is predicted by the model. The shortcomings of the model are discussed, and the model has been qualitatively modified to account for this discrepancy. The modifications centre around the significant changes in rubber wheel–particle contact geometry as the applied load is changed; such changes are difficult to model analytically due to the large strains associated with such a contact, and it is suggested that finite element modelling may be required to fully understand and model the complex contacts occurring in this simple and widely employed test method.

Effects of particle crushing in abrasion testing of steels with ash from biomass-fired powerplants

The use of biomass for firing of powerplants (either as a primary fuel or in co-firing) is gaining popularity as it is seen as a carbon-neutral energy source. The ash produced by firing with such materials causes wear of the powerplant systems designed to process it, both in the form of fly-ash and bottom-ash. In this paper, the wear behaviour of a range of steels under conditions of abrasion with biomass bottom-ash is considered. The steels were abraded using the dry sand rubber wheel test (a variant on ASTM G65) and their behaviour compared with that observed when abraded with silica in the same test. It was seen that the wear rate of the steels when abraded with silica increased in proportion to the applied load and decreased with the hardness of the steel. However, the bottom-ash was more friable than the silica abrasive, and as such, significantly more abrasive crushing was observed during the tests with the bottom-ash abrasive. As such, the wear rates with the bottom-ash did not increase in proportion to the applied load (and at higher loads they decreased with increasing applied load). Moreover, the relative abrasion rates of the steels decreased more sharply with increasing steel hardness than for the silica abrasive. The wear behaviour of the steels with the ash was dominated by the relatively low hardness of the abrasive (between that of the softest and hardest steels) and the significant crushing of the abrasive during abrasion testing. It is proposed that the wear is dominated by abrasion by the larger particles in the distribution, and that damage is limited by the maximum load which the particles can sustain before failing. As such, the abrasion rate has been shown not to be proportional to the applied load for an abrasive with a wide particle size fraction and where the particle strength results in significant particle crushing in the tests.

Abrasive wear of steel against gravel with different rock–steel combinations

Wear testing equipment and tests used in research laboratories are often miniature or simplified versions of real applications. For example standardized ASTM dry sand rubber wheel abrasion test G 65 and pin abrasion test G 132 are widely used to study materials’ abrasion wear resistance. The test results, however, do not always correlate too well with the results obtained from real wear conditions. One reason for this is, for example, that in the crushing applications of mining industry the abrasive size is usually much larger than that used in the laboratory wear tests. To study the abrasive wear caused by larger size gravel, new three-body abrasion test equipment was therefore constructed. The equipment uses the pin-on-disk principle with free abrasive particles of sizes up to 10 mm. During the test the pin is repeatedly pressed against a fixed amount of abrasive that is rotating with the disk having confining walls. As the pin is prevented from touching the counterbody, only the abrasive acts as the wearing agent. Three steels of different hardnesses were cross-tested as pin–disk pairs and as pins against a rubber disk using three igneous rock gravels with different crushability properties as abrasives. The wear was measured as mass loss from both the pin and the disk, and the rock comminution was measured by sieving. The results indicate that the mechanism of wear is greatly affected by the hardness of the counterbody. When using large size abrasives, the rate of comminution is also a very important factor that can significantly affect the wear test results.

The effects of welding processes on abrasive wear resistance for hardfacing deposits

In this research, four kinds of welding deposits were evaluated, applied through two different welding processes: flux cored arc welding (FCAW) and shielded metal arc welding (SMAW). The other variable of the tests was the deposited layers. The hardfacing deposits were evaluated using the dry sand-rubber wheel machine according to procedure A of the ASTM G65 standard. Optical and scanning electron microscopy was used for the characterization of the microstructure and worn surface of deposits. FCAW welds presented higher abrasive wear resistance than the SMAW deposits. The hardfacing deposit formed by uniformly distributed carbides rich in titanium presented the highest abrasive wear resistance. Abrasive wear resistance was higher when three layers were applied, except for SMAW-D deposit. It was not possible to get a clear relation between hardness and the abrasive wear resistance of the deposits. The results showed that the most important variable to improve abrasion resistance is the microstructure of hardfacing deposits, where the carbides act as barriers to abrasive particle cutting.

Study on abrasive and erosive wear behaviour of Al 6063/TiB 2in situ composites

In the present experimental investigation, Al 6063– xTiB 2 [ x = 0, 5, and10 weight percentage (wt.%)] in situ composites have been prepared by the reaction of mixture of K 2TiF 6 and KBF 4 with molten Al alloy at a reaction temperature of 850 °C. The wear characteristics of the composite in the as-cast conditions were studied by conducting abrasive wear test, and slurry erosive test. The abrasive wear behaviour of the metal matrix composites (MMCs) were investigated by varying parameters like wt.% of TiB 2 particles and load. Dry Sand Rubber Wheel Abrasive Wear (as per ASTM G65 standard) testing machine was used for investigating abrasive wear behaviour. It is evident from the experiments, that in situ formed TiB 2 particles offer effective coverage to the matrix and restrict the metal removal by abrasive particles. In slurry erosion, wt.% of TiB 2, distance traversed and time was used as variables. The results indicate that the wear resistance of TiB 2-reinforced material increased with increase in TiB 2 content. The overall results reveal that TiB 2 particles markedly improve the wear performance of Al 6063 alloy. The surface morphologies of the worn out surfaces were analyzed using SEM. In case of abrasive studies, the mechanism appears to be a mix-up of micro-cutting, ploughing and grain pull-out, while for erosion it is found mainly due to plastic deformation and voids.