Two-body Abrasive Tests Research Articles

Effect of Grain Refinement on Tribological Study of Low Carbon Steel

Tribological characteristics of low carbon steel (LCS) have been investigated on as-received coarse grains of 67 μm size and ultrafine-grained (UFG) microstructure of 0.2 μm size, which was prepared by equal-channel angular pressing (ECAP). Two-body abrasion tests have been carried out against silicon carbide abrasive papers at various loads. Furthermore, solid particle (silica sand) erosion tests were also conducted at normal particle impingement angles at various impact velocities. The ECAP process improved the resistance to abrasive and erosion wear of UFG LCS as compared to that of as-received coarse-grained steel. The abrasive and erosion wear resistances of UFG LCS were improved under severe conditions. The abrasive wear mechanism of as-received coarse-grained LCS was governed by micro-cutting, whereas it was microploughing in UFG LCS. The mechanism of material removal in erosive wear was brittle in as-received material in contrast to ductile in UFG steel.

Formation and wear behaviors of in-situ Al3Ti/Al composites using aluminum and titanium fibers under electromagnetic induction heating

Under various electromagnetic induction heating powers, different Al3Ti/Al composites were fabricated by in-situ synthesis method from aluminum and titanium fibers. Microstructures and particles distribution of the composites were examined by XRD, SEM and EDS. The results show that no other intermetallic compounds beside Al3Ti can be in-situ synthesized. Around the titanium fibers, the reaction zones and diffusion zones can be obviously found. Due to the stirring of the electromagnetic function, the formation of the micro-cracks inside the reaction zone was conducive to the peeling off of the Al3Ti particles, and ensures the continuous reaction between liquid aluminum and titanium fibers, as well as the diffusion of Al3Ti particles. At the same time, there were secondary splits of Al3Ti particles located in diffusion zones. Two-body abrasion test shows that with the increase of induction heating power, the wear rates of the composites reduced and the number of grooves decreased.

Abrasion resistance of polymer and polymer–ceramic composite coatings for steel hydraulic structures

There is an increased demand for abrasive wear-resistant coatings that add durability to steel hydraulic structures, particularly for those subjected to flowing water with debris and alternate wet/dry cycles. These coating systems provide not only corrosion and chemical resistance, but also good erosion and abrasion resistance to the metallic surfaces, which are constantly exposed to flowing water containing sand particles and debris. Generally, vinyl-based coatings are used on hydraulic steel structures to protect them from corrosion and abrasion. However, due to the existence of high water force and debris, the coating is abraded at a faster rate leading to significant maintenance and repair costs. In this study, abrasive wear resistance of conventional vinyl-based coating systems currently used on lock and dam steel structures by U.S. Army Corps of Engineers has been compared with polymer matrix composite coatings, fibrous polymer coatings, and ultrahigh molecular weight polyethylene (UHMWPE). Six coating systems were evaluated through two-body abrasion tests using a reciprocating abrader under dry and wet conditions. Furthermore, wettability of the coating systems and its effect on the wear rate under the presence of water was studied. In addition, scanning electron microscopy of the wear tracks on different coatings was conducted to study and identify their failure mechanisms. Based on the results, UHMWPE and polymer–ceramic composite coatings were found to perform significantly better than the conventional vinyl-based coatings.

Investigation on Thermal and Tribological Properties of Polypropylene/Spheri Glass 3000 Composites Processed by Melt Intercalation Method

The polymer composites show a remarkable improvement in their properties when compared to the virgin thermoplastic polymer materials, and it finds its application in several fields. In the current research work Polypropylene (PPE) was chosen as a thermoplastic matrix and Spheri Glass 3000 (SG3) as the filler. The SGE was added at 0, 1.25, 2.5 and 5 wt.% to PPE matrix. The processing of PPE and PPE/SGE was done using a twin screw extruder. Injection moulding was used for producing the test specimens. The processed PPE/SGE composites were characterised by X-ray diffraction, dispersion studies density, Melt Flow Index (MFI), Heat Deflection Test (HDT) and abrasive wear tests. The abrasive wear test by means of two-body abrasive test was carried out with input factors like (i) sample (0, 1.25, 2.5 and 5 wt.%), (ii) applied load (10, 20, 30, 40 N) and (iii) sliding velocity (0.5, 1.0, 1.5 and 2.0 m/s) under a constant sliding distance of 500 m. The influencing factors of the two-body abrasive wear tests were studied by Analysis of Variance (ANOVA). Finally, the worn surface morphology of the abraded surface was studied using a Scanning Electron Microscope (SEM).

Processing and Characterization of Fe-Mn-Cu-Sn-C Alloys Prepared by Ball Milling and Spark Plasma Sintering

In this work, Fe-Mn-Cu-Sn-C alloys were prepared by means of powder metallurgy (PM). Powder mixtures were ball-milled for 8, 30 and 120 h and densified to < 1% porosity using spark plasma sintering (SPS) at 900 °C and 35 MPa. After consolidation, all samples of the Fe alloys were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), hardness and flexural strength tests. Resistance to abrasive wear was evaluated in both three-body abrasion and two-body abrasion tests. The SEM observations revealed an evident dependence of grain size and microstructural homogeneity on milling time. The XRD analysis showed a marked increase in austenite content in the as-sintered specimens with milling time. Although the proportion of deformation-induced martensite was small, the strengthening effect of abrasion on the subsurface layer of the investigated alloys was clearly indicated by Knoop hardness measurements.

Effect of isothermal quenching on microstructure and properties of a forged and unforged Fe-B cast alloy

Abstract The effect of isothermal quenching on microstructure and properties of forged and unforged Fe-B cast alloy were investigated in this paper. The prepared samples were analyzed using scanning electron microscope (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that, after isothermal quenching, the matrix transforms into lower bainite, but the morphology of boride remains nearly unchanged compared with its as-cast condition. Compared with water quenching, the hardness of forged and unforged samples after isothermal quenching is lower than the hardness of that after water quenching. The impact toughness of forged and unforged samples after isothermal quenching is higher than after water quenching. In two-body abrasion test, the wear resistance of forged and unforged samples after isothermal quenching is lower than that of forged and unforged samples after water quenching. In three-body abrasion test, the wear resistance of forged and unforged samples after isothermal quenching shows opposite behavior and is higher than that of forged and unforged samples after water quenching.

Role of the strengthening phases in abrasive wear resistance of laser-clad NiCrBSi coatings

The influence of the strengthening phases on the tribological characteristics (wear intensity, specific work of wear, coefficient of friction) and the wear mechanisms in two-body abrasion tests with abrasives of different hardnesses (corundum Al2O3, ~2000 HV and silicon carbide SiC, ~3000 HV) has been investigated for PG-SR2 (Cr23C6, 1000–1150 HV), PG-10N-01 (Cr7C3, 1650–1800 HV; CrB, 1950–2400 HV), and 75% PG-SR2 + 25% TiC (TiC, 2500–2900 HV; (Cr,Ni)23(C,B)6 and (Ti,Cr)(C,B), ~2000 HV) coatings. The dominant role of the strengthening phases (compared with the role of the metal matrix) in the abrasive wear resistance of laser-clad NiCrBSi coatings has been estimated. Different wear mechanisms have been identified and, accordingly, different levels of coatings wear resistance have been achieved depending on the ratio between the hardness of the strengthening phases (carbides, borides, carboborides) and abrasive particles.

On replacing three-body abrasion testing with two-body abrasion testing

The dry sand rubber wheel abrasion test (ASTM G 65) is probably the most widely used abrasion test. It has been used for decades with favorable results. However, this test was developed when tool steels and fusion hardfacings were the materials usually ranked with this low-stress sand abrasion test. Two major problems have emerged in the use of this test: 1. The abradant (silica sand) is not aggressive enough for many modern materials. 2. There are many issues with the variability and availability of the rubbers used to force the abrasive against the test surface.This project was initiated to investigate the viability of using the ASTM G 174 loop abrasion test to replace or supplant the ASTM G 65 test. Friction tests were conducted on various substrates with rubbers wheels used in the three-body testing to understand the interface between the rubber and the abrasive. Limited tests were also conducted on replacing the rubber wheel in the three-body test with a steel wheel. Finally tests were conducted to develop a correlation between ASTM G 65 test results and ASTM G 174 test results. The friction tests confirm that various rubbers interact very differently with abrasives and substrates. A steel wheel cannot be used with the current ASTM G 65 force. The sand crushes to powder. However, a correlation curve was developed to allow conversion of historical ASTM G 65 data to results obtained with the ASTM G 174 two-body abrasion test. Overall this study suggests that two -body abrasion testing with aluminum oxide eliminates rubber issues and the aluminum oxide is abrasive enough to rank modern composites and cermets that are too wear-resistant for a sand abrasion test.

Comparison of Wear Resistance Between Innovative Composites and Nano- and Microfilled Composite Resins

Background: One of the most common causes of failure in class 2 posterior composite restorations is occlusal and proximal wear. Estelite composites used supra-nano monodispersing spherical fillers and a new photoinitiator, and the manufacturer claimed that the wear of these composites is less than 1 mm3 volumetric wear. Objectives: Compare the wear resistance of new Estelite composites with that of other composites generations. Materials and Methods: Thirty-five specimens were evaluated in five groups: three kinds of Estelite composites (Estelite Sigma Quick, Estelite Flow Quick, and Estelite Flow Quick High Flow), Filtek Z350, and Filtek Z250. All specimens were prepared in 25 mm disks and cured with laboratory light for 120 seconds (60 s for each side). Then, they were polished by 600 grit sand paper and stored for one week in distilled water at room temperature. We used a two-body abrasion test and the pin-on-disk method with distilled water as medium. All specimens were worn under 15 N load, 0.05 m/seconds speed, 100 m distance, and steatite ceramic balls antagonists. After wearing, we measured wear volume by calculating the wear track cross-section area with a profilometer and analyzed the data with the one-way analysis of variance (ANOVA) test. Results: The wear amounts of the composites are as follows in order: Estelite sigma quick (1886.9 ± 518.5 µm 2 ), Estelite flow quick (2708.9 ± 578.1 µm 2 ), Estelite high flow (3206 ± 2445.1 µm 2 ), Filtek Z350 (3840 ± 1963.4 µm 2 ), and Filtek Z250 (4667.2 ± 2351.1 µm 2 ). No statistical difference was found among the groups (P value > 0.05). Conclusions: Estelite sigma quick composite had wear resistance similar to that of nano- and microfilled composites. Estelite flowable composites demonstrated similar wear resistance to that of a posterior composite.

Fissure sealant materials: Wear resistance of flowable composite resins.

Background. Wear resistance of pit and fissure sealant materials can influence their retention. Wear characteristics of sealant materials may determine scheduling of check-up visits. The aim of this study was to compare wear resistance of two flowable composite resins with that of posterior composite resin materials.Methods. Thirty-five disk-shaped specimens were prepared in 5 groups, including two flowable composite resins (Estelite Flow Quick and Estelite Flow Quick High Flow), Filtek P90 and Filtek P60 and Tetric N-Ceram. The disk-shaped samples were prepared in 25-mm diameter by packing them into a two-piece aluminum mold and then light-cured. All the specimens were polished for 1minute using 600-grit sand paper. The samples were stored in distilled water at room temperature for 1 week and then worn by two-body abrasion test using "pin-on-disk" method (with distilled water under a 15-Nload at 0.05 m/s, for a distance of 100 meter with Steatite ceramic balls antagonists). A Profilometer was used for evaluating the surface wear. Data were analyzed with the one-way ANOVA.Results. Estelite Flow Quick exhibited 2708.9 ± 578.1 μm2 and Estelite Flow Quick High Flow exhibited 3206 ± 2445.1 μm2of wear but there were no significant differences between the groups. They demonstrated similar wear properties.Conclusion. Estelite flowable composite resins have wear resistance similar to nano- and micro-filled and micro-hybrid composite resins. Therefore, they can be recommended as pit and fissure sealant materials in the posterior region with appropriate mechanical characteristics.

Effect of Hot Forging on Microstructure and Abrasion Resistance of Fe-B Alloy

The effect of hot forging on the microstructure and abrasion resistance of Fe-B alloy was studied. The results showed that boride networks are broken down by hot forging. After hot forging, the hardness of Fe-B alloy increased marginally, and the toughness increased considerably. In the two-body abrasion test, unforged Fe-B alloy exhibited excellent wear resistance and soft abrasive tended to show higher wear resistance. When alloys were tested against very hard abrasives, the wear resistance of forged Fe-B alloy was similar to that of unforged Fe-B alloy, but in the case of soft abrasives the wear resistance of forged Fe-B alloy was lower than that of unforged Fe-B alloy.

Development of a two-body wet abrasion test method with attention to the effects of reused abradant

A simple test method has been developed to quantify the response of metals and alloys to two-body wet abrasion. A metallographic polishing machine was modified to create a disk-on-flat sliding test rig. Adhesive-backed SiC grinding papers were used under fixed load and speed to rank the abrasive wear of seven alloy steels, some of which are candidates for drill cones for geothermal drilling. Standardized two-body abrasion tests, like those described in ASTM G132, feed unused abrasive into the contact; however, the current work investigated whether useful rankings could still be obtained with a simpler testing configuration in which specimens repeatedly slide on the same wear path under water-lubricated conditions. Tests using abrasive grit sizes of 120 and 180 resulted in the same relative ranking of the alloys although the coarser grit produced more total wear. Wear decreased when the same abrasive disk was re-used for up to five runs, but the relative rankings of the steels remained the same. This procedure was presented to ASTM Committee G2 on Wear and Erosion as a potential standard test for wet two-body abrasive wear.

Validation of proposed metrics for two-body abrasion scratch test analysis standards

The objective of this work was to evaluate a set of standardized metrics proposed for characterizing a surface that has been scratched from a two-body abrasion test. This is achieved by defining a new abrasion region termed Zone of Interaction (ZOI). The ZOI describes the full surface profile of all peaks and valleys, rather than just measuring a scratch width as currently defined by the ASTM G 171 Standard. The ZOI has been found to be at least twice the size of a standard width measurement, in some cases considerably greater, indicating that at least half of the disturbed surface area would be neglected without this insight. The ZOI is used to calculate a more robust data set of volume measurements that can be used to computationally reconstruct a resultant profile for detailed analysis. Documenting additional changes to various surface roughness parameters also allows key material attributes of importance to ultimate design applications to be quantified, such as depth of penetration and final abraded surface roughness. Data are presented to show that different combinations of scratch tips and abraded materials can actually yield the same scratch width, but result in different volume displacement or removal measurements and therefore, the ZOI method is more discriminating than the ASTM method scratch width. Furthermore, by investigating the use of custom scratch tips for our specific needs, the usefulness of having an abrasion metric that can measure the displaced volume in this standardized manner, and not just by scratch width alone, is reinforced. This benefit is made apparent when a tip creates an intricate contour having multiple peaks and valleys within a single scratch. This work lays the foundation for updating scratch measurement standards to improve modeling and characterization of three-body abrasion test results.

Effect of abrasive particle size on abrasive wear of hardfacing alloys

Hardfacing is one of the most useful and economical ways to improve the performance of components submitted to severe wear conditions. This study has been made for the comparison of microstructure and abrasion resistance of hardfacing alloys reinforced with chromium carbides or complex carbides. The hardfacing alloys were deposited onto ČNS EN S235JR low carbon steel plates by the gas metal arc welding (GMAW) method. Different commercial hardfacing electrodes were applied to investigate the effect of abrasive particle size on abrasive wear resistance. The abrasion tests were made using the two-body abrasion test according to ČSN 01 5084 standard, abrasive cloths were of grits 80, 120, 240, and 400. Microstructure characterisation and surface analysis were made using optical and scanning electron microscopy. The results show the different influence of abrasive particles size on the wear rate for different structures of Fe-Cr-C system. The structures without primary carbides are of high abrasive wear rate, which increases nonlinearly with the increasing abrasive particle size. On the contrary, the structures containing primary carbides are of low abrasive rates and theses rates increase linearly with the increasing abrasive particle size.

Tribological stability of Al 2O 3 short fiber reinforced high Cr cast irons

To develop super abrasion resistant materials, Al 2O 3 short fiber reinforced high Cr cast irons with a range of fiber volume fractions were fabricated by an infiltration process. Abrasion tests were carried out with a Suga-type (two-body) tester and a rubber wheel (three-body) abrasive tester at room temperature, and with a low-stress abrasion tester at 923 K, respectively. Microstructure observations revealed that the presence of alumina fibers greatly refines the solidification structures of the matrix alloys. The results of the wear tests show that the abrasion resistance of high Cr cast irons at both room and elevated temperature was improved by the presence of Al 2O 3 fibers. In the two-body abrasion tests, the wear rates of the hypo- and hyper-eutectic composites were 92 and 88% of that of the monolithic materials, respectively, while in the three-body abrasion tests, these wear rate ratios were 38 and 88%, respectively. At 923 K, the hypo-eutectic composite with a fiber volume fraction of 20% exhibited the smallest wear rate, and a decrease in wear rate with increasing fiber volume content was demonstrated in the hyper-eutectic composites. It was concluded that the presence of Al 2O 3 fibers in high Cr cast irons is useful for abrasion resistance.

Scale effects in abrasive wear of composite sol–gel alumina coated light alloys

Chemically-bonded composite sol–gel (CB-CSG) coatings have been developed that incorporate calcined ceramic powder particles (filler) dispersed in a sol–gel (SG) matrix (binder). As a result, they have significantly reduced densification strains compared to conventional SG coatings. The CB-CSG coatings, which are several orders of magnitude thicker than typical micron-thick SG films, can be produced easily by spray depositing onto Al and Mg alloys, followed by a short low temperature (300°C) heat treatment. The abrasive wear performance was determined for Al 2O 3(binder)/Al 2O 3(filler), Al 2O 3(binder)/Al 2O 3-SiC (fillers) and a hybrid Al 2O 3(binder)/Al 2O 3(filler)+Al (40 μm particle filler) coatings on commercial Al and Mg alloys. In two-body abrasion tests, the coated alloys were abraded by bonded SiC abrasives of increasing coarseness with comparative experiments also being performed on the uncoated substrate alloys. Coating wear rates exhibited an order of magnitude increase when the scale of indentation increased above a critical depth, whereupon wear rates approached those of the substrate alloy. Similar observations were made in three-body microabrasion experiments using a ball-cratering technique to abrade the coatings with very fine and coarse alumina slurries. The modes and mechanisms of coating damage were characterized by SEM and optical surface profilometry techniques. Normalized parameters for hardness, abrasive wear and indentation depth, were used in interpreting and comparing coating tribological performance.

Computer simulation of two-body abrasion processes

Two-body abrasion processes should be considered as random processes due to the characteristics of abrasive papers. In this paper, the Monte Carlo modelling of abrasion processes is proposed. Using the Monte Carlo method, a random abrasive paper is formed. To consider the effect of ploughing ridge, the curves of Böklen and Azarkhin–Richmond are introduced in the modelling. Simulative computing is carried out to verify the well-known relations of material hardness, particle size and normal load with wear rate. The results show that the simulation is in good agreement with those of two-body abrasion tests.

Two-body abrasive wear of Al–SiC composites

The two-body abrasive wear behaviour of aluminium matrix composites reinforced with silicon carbide particles has been investigated. The metal matrix composites were fabricated by a powder metallurgy route involving a final hot extrusion step, with Al 1100 matrix and α-SiC p reinforcement with mean sizes of 10, 27 and 43 μm, in the proportions of 5, 10 and 20 vol.%. Using a pin-on-disc apparatus, two-body abrasion tests were carried out against silicon carbide and alumina abrasives with four different grit sizes. The microstructural characterisations were performed using light microscopy. The dominant wear mechanisms were evaluated using scanning electron microscopy. It was shown that SiC p particles reinforcement improved the abrasion resistance against all the abrasives used. This improvement generally was higher against alumina than against silicon carbide. The abrasion resistance increased with an increase in the volume fraction and size of SiC p particles reinforcement. The results also showed that the abrasion resistance decreased with increasing the relative abrasive penetration depth, until a critical value; above this limit, the abrasion resistance was generally independent of the penetration depth.

An experimental simulation of cutting wear in three-body abrasion

Plastic deformation wear and cutting wear are two of the major types of wear that occur in three-body abrasion of materials. The authors' previous work has shown that cutting wear has a strong influence on the relationship between the wear loss and the hardness of materials. Often the curve of the wear loss relative to material hardness appears S-shaped because of the dependence on cutting wear. However, the detailed mechanism of this process is still unclear at present. In the present paper two-body abrasion tests were carried out to simulate the cutting wear in three-body abrasion of materials with a range of hardness values. It is concluded that maximum cutting wear intensity occurs as the hardness of the tested materials is varied. This is the underlying reason behind the S-shaped characteristic of three-body abrasion of materials.

On the abrasive wear of zirconias

Zirconia ceramics with different dopants, used to retain the tetragonal phase metastably, were evaluated to determine the effect of the difference in degree of transformability on the abrasive wear behavior. The abrasive wear tests, carried out on a multiple abrasive wear tester, showed that for two-body and three-body configurations the wear rate increases for higher normal loads and abrasive grain sizes. The specimen with low degree of transformability presented the worst behavior in every configuration owing to its low fracture toughness. For the three-body configuration, the specimen with intermediate degree of transformability presented the best behavior; this was associated with its higher hardness and flexural strength. For two-body abrasive tests, the change in wear severity conditions led to an inversion of wear behavior of the specimens with a high degree of transformability. The results obtained were associated with the microstructure generated, the physical and mechanical properties and the tetragonal to monoclinic transformation rates, since the stress induced transformation could be inhibited owing to the temperature developed in the contact between the zirconia sample and the abrasive material. Finally, the comparison between zirconia and white cast iron wear behavior under two different conditions revealed that the performance of zirconias was favorable only for low severity wear conditions and for intermediate and high degrees of transformability.