Micro-scale Abrasion Test Research Articles

Effects of niobium and molybdenum addition on microstructural characteristics and wear properties of 14 wt%Cr white cast irons

White cast iron (WCIs) alloys were developed by adding Nb, Mo, and a combination of both (∼3 wt% Nb, ∼3 wt% Mo, ∼1 wt% Mo-2 wt% Nb) through melting and casting. The objective was to analyze the microstructural characteristics of the alloys, as well as the impact of reinforcing carbides on their mechanical and tribological properties. The alloy containing the highest percentage of niobium exhibited a refined microstructure, tending towards a eutectic structure, unlike the Mo-containing materials with totally hypoeutectic microstructures. The microstructural characteristics of the alloys and morphology of niobium carbides, as well as the percentage of M7C3 eutectic carbides produced were affected by the varying percentages of Nb and the Mo–Nb combination. Moreover, thermodynamic simulations revealed that the NbC carbide precipitated before the M7C3 eutectic carbides, austenite dendrites, and the MC (composed mainly of Nb containing bound Mo) carbide resulting from the Mo–Nb combination. The alloys containing Mo had similar bulk hardness values, while the alloy with the highest percentage of Nb showed a higher bulk hardness value. This was attributed to the effect of Nb on microstructure refinement and on the production of M7C3 eutectic carbides from the alloy. Although there were different reinforcing carbides (NbC, MC and M2C), the differences in microstructural characteristics had no noticeable influence on the Charpy impact energy. Micro-scale abrasive wear test (conducted with SiC abrasive slurry) demonstrated that the reinforcing carbides MC and mainly NbC had a beneficial effect in blocking and preventing the progression of continuous micro-cuttings and formation of grooves. The M7C3 and M2C carbides were less effective at protecting the matrix against the high-hardness SiC abrasive.

Cu-based thin rolled foils: relationship among alloy composition, micromechanical and antiviral properties against SARS-CoV-2

The healthcare-associated infections (HAIs) and pandemics caused by multidrug-resistant (MDR) and new-generation pathogens threaten the whole world community. Cu and its alloys have been attracting widespread interest as anti-contamination materials due to the rapid inactivation of MDR-superbugs and viruses. Applying thin Cu-based foils on pre-existing surfaces in hygiene-sensitive areas represents a quick, simple, cost-effective self-sanitising practice. However, the influence of chemical composition and microstructure should be deeply investigated when evaluating the antimicrobial capability and durability of Cu-based materials. The effect of composition on micromechanical and antiviral properties was investigated by comparing Cu15Zn and Cu18Ni20Zn (foil thickness from 13 to 27 μm) with Phosphorous High-Conductivity (PHC) Cu. The influence of recrystallisation annealing of PHC Cu was also investigated. Microstructural characterisation was carried out by optical (OM) and scanning electron (FEG-SEM) microscopy, Energy-dispersive Spectroscopy (EDS) and Electron-Backscattered Diffraction (EBSD). The micromechanical behaviour was assessed by microhardness, microscale abrasion and scratch tests. Cu-based foils were exposed to SARS-CoV-2 for different time points in quasi-dry conditions (artificial sweat solution), evaluating their antiviral capability by quantitative Reverse-Transcriptase Polymerase Chain Reaction (qRT-PCR). Surface morphology, contact angle measurements and Cu release were measured. All Cu-based surfaces completely inactivated SARS-CoV-2 in 10 min: pure Cu was the best option regarding antiviral efficiency, while Cu15Zn showed the best trade-off between micromechanical and antiviral properties.

Micro-Scale Abrasive Wear Resistance of a Nanoceramic Sealant Applied on Galvanized Low Carbon Steel

The idea for this work came from a market need to obtain coatings or sealants that would extend the useful life of metallic materials in applications that involve exposure to corrosive environments. The main objective of the nanoceramic sealant studied in this work is to extend the life of metallic fasteners. To evaluate the performance of the sealant from other perspectives, microstructural analysis, adhesion test, micro-scale abrasive wear tests and corrosion test were carried out. These tests were performed on samples coated only with white zinc, which is commonly used in the fastener industry, and on samples coated with white zinc followed by application of the nanoceramic sealant. The application of the nanoceramic sealant contributed to the improvement of corrosion resistance and reduction of the corrosion rate. The corrosion rate of the sample coated with the sealant reduced by 62.2% when compared to the sample that only went through the white zinc coating process. The coating showed low adhesion to the substrate with the presence of severe delamination and microcracks. This feature contributed to the low wear resistance presented by the coating under the conditions studied in this work. Less attention, compared to studies involving corrosion resistance, has been given to wear resistance in the fastener industry. The results obtained in this paper show that the study of tribological behavior is an important factor in increasing the efficiency of fasteners applied in harsh environments.

Comparative Micro-Scale Abrasive Wear Testing of Thermally Sprayed and Hard Chromium Coatings

Nowadays, due to the carcinogenic effects of chrome, replacing the hard chromium used for hydraulic components like rods and cylinders is becoming increasingly requested. Thermally sprayed coatings are a solution to the problem; however, proper understanding and characterisation of their tribological behaviour are essential for the successful exploitation of surface engineering. Thus, the main aim of this study is to evaluate the abrasive wear characteristics of two metal sprayed layers, tungsten carbide (WC) deposited through the high-velocity oxygen fuel coating (HVOF) method and Fe alloy coating deposited through thermal spraying with an electric arc with a wire-electrode G3Si1, and compare the results with those of an electrochemically deposited hard chromium layer. Their wear resistance is then related to their hardness. The results highlight the tribological performances of the thermally sprayed coatings. The HVOF WC10Co4Cr coating has a wear coefficient and a material wear volume that are hundreds of times lower than those of the other two coatings.

Abrasive Wear Resistance of High-Strength Compacted Graphite Iron under Microabrasion Conditions

Compacted graphite iron (CGI) has been considered an excellent option for heavy-duty engine blocks due to its superior mechanical properties, which allow reduction of weight, enhancing engine performance. Abrasion is a recognized wear mechanism in engine blocks, meaning it deserves to be evaluated for CGI. This study analyzed two grades of high-strength CGI (GJV450 and GJV500) submitted to microscale abrasion tests in free ball configuration using two different slurries: diamond and silica. There was more wear to the surfaces tested with silica due to the particle size, which was one order of magnitude larger than the diamond. The data obtained showed that both materials presented similar resistance when tests were performed with the diamond slurry. On the other hand, when silica was used, GJV500 presented 2.5 times greater wear resistance than GJV450, even though its global hardness was only 17% greater.

Wear Regimes of Fe–Cr–C Hardfacing Alloys in Microscale Abrasion Tests

Wear Regimes of Fe–Cr–C Hardfacing Alloys in Microscale Abrasion Tests

Combined effect of abrasive particle size distribution and ball material on the wear coefficient in micro-scale abrasive wear tests

Micro-abrasive wear tests were carried out to analyze the combined effect of abrasive particle size distribution and ball material on the wear coefficient. Different particle size distributions were obtained by mixing different fractions of two silicon carbide (SiC) abrasive powders, having average particle sizes of 6.0 μm and 14.4 μm. Tests were conducted using two different normal loads, 0.2 and 0.4 N, AISI 1020 steel samples and balls made of AISI 52100 martensitic steel, AISI 304 austenitic stainless steel, polyurethane rubber and zirconia-alumina. Worn surfaces were analyzed with Scanning Electron Microscopy (SEM) and by optical profilometry. Results have indicated that a change in ball material, with consequential modification in the ratio between the hardness of the body and the counter-body, enabled different behaviors of the wear coefficient with the variation of the granulometric distribution. Such differences are due to the ability of the particles to be embedded and dragged into contact. The wear coefficients were analyzed in each case, resulting in a map to describe the combined influence of granulometric distributions of abrasive particles and ball material on the wear coefficient.

On the Use of Microscale Abrasion Test for Determining the Particle Abrasivity

Abstract Particle abrasivity is an important concept for helping to select materials for pumps and for disc cutters in underground excavation, and specific ASTM standards are available for making these selections. However, for manufacturing processes in which abrasive action is their core, the particle size range is approximately a few micrometers. The evaluation of particle abrasivity using the microscale abrasion test matches this range of particles for this purpose, but relatively few investigations using this kind of method have been conducted. The aim of this investigation is to use the microscale abrasion test to evaluate the particle abrasivity, avoiding changes on the ball surface and on the particle size distribution. Samples of quenched AISI D2 tool steel were used for tests. The wear mode was dependent on the testing time. Alumina (Al2O3) particles presented a lower abrasiveness when compared to boron carbide (B4C) ones, confirmed by the higher wear coefficient found in the latter after reaching the steady-state regime. This behavior was evidenced by the number of active particles in the contact, which showed that there were a larger number of B4C particles than Al2O3 during the contact at all sliding distances. The particle abrasivity is discussed in terms of significant characteristics of slurries: particle shape, particle size distribution, hardness-to-elastic modulus ratio, zeta potential, and density. As the controlling of those characteristics seems to be very important, particle abrasivity is a concept that needs to be improved besides the test system used for that purpose.

The effect of plasma nitriding on the synergism between wear and corrosion of SAF 2205 duplex stainless steel

PurposeThis study aims to assess the performance of SAF 2205 duplex stainless steel against pure wear, tribo-corrosion, corrosion and the synergism between wear and corrosion. The effect of plasma nitriding conducted at low temperature (380°C) on SAF 2205 steel was analyzed.Design/methodology/approachThree systems were used for assessing the synergism between wear and corrosion: tribo-corrosion – wear tests conducted using the micro-scale abrasion test, performed under a slurry of alumina particles containing 3.5% NaCl; pure wear – tests conducted using the previous system but isolated in a glovebox with a 99% N2 atmosphere; and cyclic polarization under 3.5% NaCl solution. A hard nitrided layer of 3 µm thickness was characterized using X-ray diffraction, presenting expanded austenite.FindingsThe wear mode after micro-scale abrasion tests changed in the absence of an oxygen atmosphere. During pure wear, a mixed mode was identified (rolling + grooving), with the grooving mode more intense for the untreated steel. For tribo-corrosion tests, only rolling wear was identified. For all cases, the nitrided samples presented less wear. The corrosion results indicated a higher repassivation potential for the nitrided condition.Practical implicationsThe synergism was more positive for the nitrided sample than for the untreated one, which can be considered for surface treatments of duplex stainless steels in practical applications.Originality/valueA detailed description of wear mechanisms showed a significant change in the presence of oxygen atmosphere, a new approach for isolating pure wear.

Micro-scale abrasion and sliding wear of zirconium-lithium silicate glass-ceramic and polymer-infiltrated ceramic network used in dentistry

The main aim of the present study was to evaluate the micro-scale abrasion and sliding wear behavior of a zirconium-lithium silicate (ZLS) glass-ceramic and a polymer-infiltrated ceramic network used in dentistry. Samples were assessed on a reciprocating ball-on-plate tribometer at 30 N normal load, 1 Hz and stroke length of 2 mm. The wear sliding tests were carried out against an alumina ball in artificial saliva at 37 °C. Also, micro-scale abrasion tests were performed in the presence of abrasive particles to simulate three-body abrasion conditions. The micro-scale abrasion tests were performed at 60 rpm on 0.8 N normal load for 600 revolutions of a stainless-steel ball in contact with a suspension of hydrated silica particles. After wear tests, the worn surfaces were inspected by scanning electron microscopy (SEM). Abrasion was the main wear mechanism found during the tests. However, the hybrid ceramic revealed an unstable adhesive tribo-layer, associated with a delamination process. The wear volume mean values recorded after the micro-abrasion tests were significantly higher for the polymer infiltrated ceramic network (~1.44 x10-1 mm3) than those for the ZLS glass-ceramic (~9.89 x10-2 mm3). Also, the mean values of specific sliding wear rate were higher for the polymer-infiltrated ceramic network (~5.33 x10-5 mm3/N.m) than those for the ZLS glass-ceramic ZL(~3.17 x10-5 mm3/N.m). For all test conditions, zirconium-lithium glass-ceramic revealed higher wear resistance and lower friction coefficient when compared to the polymer-infiltrated ceramic network. The findings indicated a less damage of glass-ceramics in comparison to polymer-matrix composites on sliding loading or micro-scale abrasion that can occur during the masticatory process.

Case study: Abrasive capacity of Limnoperna fortunei (golden mussel) shells on the wear of 3 different steel types

The impact of particles suspended in the water is responsible for the wear of mechanical surfaces in hydraulic systems. The characteristics and concentrations of these particles in the flow directly influence the intensity of the abrasion processes. Within this context, knowledge of the abrasive power of a particle is of great importance. It is known that an invasive species, known as golden mussel shell, has become embedded in several hydroelectric plants of the South and Southeast of Brazil, provoking an increase of the wear caused by shells that pass through the hydraulic system. In this context, the abrasive capacity of ground golden mussel shells on the three metallic materials used in the labyrinth component of the hydraulic turbines was analyzed. To determine the wear pattern and the relationship of the specific wear coefficient of the material (k), due to the increased concentration of golden mussel shell, micro-scale abrasive wear tests were performed on three different steel plates using abrasive suspensions at different concentrations of ground golden mussel shell in distilled water. The abrasivity of the golden mussel shell was also compared with the abrasivity of silicon carbide (SiC), commonly used as standard material in microabrasion tests. The analyses showed that the golden mussel shell is around 16 times less abrasive than the silicon carbide, taking into account the average obtained for the three different materials tested. In addition, the wear mechanisms acting on the SiC tests and those with the golden mussel shell were the same.

Effect of Al2O3 particles on the adhesion, wear, and corrosion performance of epoxy coatings for protection of umbilical cables accessories for subsea oil and gas production systems

Umbilical cables accessories of subsea oil and gas production systems are exposed to very high mechanical stresses, abrasive wear, and continuous electrolyte action in submerged condition. Epoxy-based composite coatings with ceramic loading have been studied for providing protection to the accessories. By adding micro-Al2O3 particles to the polymeric matrix, the corrosion and wear properties are expected to be improved without a significant impact on the cost as compared with unmodified epoxy coating. In order to evaluate the tribological properties, adhesion and micro-scale abrasive tests have been performed on epoxy before and after loading of 26vol.% micro Al2O3 particles. The results showed that wear resistance and adhesion to the substrate of ceramic-loaded epoxy increased by 30% and 50%, respectively. Electrochemical impedance spectroscopy tests were also performed and higher resistances of epoxy with ceramic loading were confirmed, which indicate a more efficient barrier against electrolyte permeation. In addition, coatings with thicknesses of 120μm, 240μm, and 360μm were evaluated and the results showed that the resistances of both coatings increased with the increase in the thickness. Thus, the loading of micro Al2O3 particles into epoxy resin matrix increased its adhesion, wear, and corrosion resistances without significant impact on the cost, which renders the use of this coating in umbilical accessories feasible.

Micro-scale abrasion wear of novel biomedical PEEK-matrix composites for restorative dentistry

Novel PEEK-based composites have been studied to replace metallic biomedical implant and prostheses although the influence of aggressive oral conditions should be understood such as wear in the presence of toothpaste abrasive particles. The main aim of this study was to assess the micro-abrasion performance of novel PEEK-based composites embedding biocompatible inorganic fillers composed of (LZSA) lithium-silicate glass ceramic or (NASF) natural silica fibers. PEEK powders were mixed with 10 and 30 wt% LZSA or NASF to produce composite structures by using hot pressing technique. After polishing and cleaning procedures, test surfaces were assessed by micro-scale abrasion tests at on 0.8 N at 600 ball revolutions in contact with an abrasive suspension of 6 wt% amorphous silica particles with mean size at 8–10 μm. The worn and unworn surfaces were inspected by scanning electron microscopy (SEM) and optical profilometry. SEM images revealed aligned abrasion grooves on all the test surfaces. The largest damaged area was noticed on PEEK free of inorganic fillers while the lowest micro-abrasion damage was recorded on PEEK embedding 10%LZSA. The micro-abrasion resistance of PEEK-LZSA composites was negatively affected by the increase of inorganic content as seen on 30%LZSA. However, PEEK-based composites showed a higher micro-abrasion wear resistance than that on non-reinforced PEEK. The wear resistance can be enhanced by adding an adequate content and shape of inorganic fillers. Further studies should investigate the effect of morphology and properties of inorganic fillers to improve the wear performance of PEEK-based composites.

Case study: Effects of sediment concentration on the wear of fluvial water pump impellers on Brazil's Acre River

The most important factor causing surface wear in hydraulic systems is the impact produced by abrasive particles suspended in the water flow. The impact conditions, such as mean particle velocity; particle mass; abrasive particle concentration in the liquid flow (number of particles per unit of liquid volume, size distribution of the particles); angle of attack at which the particles collide with the surface; and duration of the effect produced by the particles on the surface contribute to the development of the abrasion process. The wear resistance of the centrifugal pump impellers depends on the characteristics of the materials used in their manufacture and the abrasiveness of the suspended sediments in the pumped water. Despite special care in choosing the material used in its manufacture, abrasive wear is practically impossible to totally avoid. This work analyses the wear of ductile cast iron impeller blades of a centrifugal pump, used at the Fluvial Water Elevation Station (FWES) of the Acre River sedimentary basin in Brazil, due to the sediment concentration variation and the river water level. To determine the wear pattern and the relationship between the material and specific wear coefficient (k) due to increased sediment concentration, a ball-cratering microscale abrasive wear test was performed on samples of ductile cast iron, withdrawn from a used impeller, and abrasive suspensions at concentrations of 1, 2, 3, 5 and 10 g L−1 of river sediment in distilled water. The wear volume to the impeller blades due to the relative velocity of the mixture (water + sediment) and the wear accumulated in an annual hydrological cycle were estimated mathematically. The results showed that: i) the k remains constant regardless of the normal force (FD) applied in the tests in the abrasometer; ii) the wear tests showed the abrasive capacity of the sediments at different concentrations; and iii) the rotational control of the pump speed based on the sediment concentration and the river water level can contribute to a reduction in wear of up to 30% considering the hydrological cycle.

Micro-Scale Abrasive Wear Testing of CrN Duplex PVD Coating on Pre-Nitrided Tool Steel

Specific wear rates were calculated from a series of micro-scale abrasive tests by means of the calotte-grinding method. The tested material was a CrN coating deposited by arc evaporation on ion-nitrided AISI H13 steel. Characterizations included: phase analysis, chemical composition, metallography, microhardness, micro-scratch resistance and nano-indentation hardness. On wear testing, the counter body was a 30 mm diameter steel ball rotating at a tangential speed of 9.42 m/min and normal load of 0.54 N. The abrasive was a mono-crystalline diamond micro abrasive paste, 1 micrometer grit. Wear volumes were calculated by measuring the wear scars at various test intervals. In non-perforating tests, Archard's wear equation was directly employed for calculating coating wear rate as the slope of the linear least square data fit. In perforating tests, Allsopp's method was employed for the simultaneous determination of coating and substrate wear rates, from the slope and intercept values of the linear least square data fit. Coating specific wear rate values obtained from both non-perforating and perforating tests were very consistent, with a relative difference within 6%. Relative errors in specific wear rate values were estimated to be of the order of 0.05 for the coating and 0.2 for the substrate.

Micro-scale abrasive wear of some sealing elastomers

This work aims to investigate the micro-abrasive wear of some common sealing elastomers by the micro-scale abrasion test. It has been employed to try hard materials, such as: mild steel, Cr-white cast iron, aluminum alloys, tool steel, polymers, etc, since it exhibits good accuracy and repeatability, however, it has not been implemented to test elastomers. In dynamic seals, micro-abrasive wear is produced because hard micro-debris are dragged by the lubricant film to the sealing interface during the machine operation, which accelerates the normal lubricated sliding wear. In order to see the capability of the micro-abrasion test to evaluate sealing elastomers, four materials were tried under different loads and progressive sliding distances using a TE66 micro-scale abrasion tester. The morphology of the wear scars was studied by SEM images. Hence, particular micro-abrasive wear patterns were found. Also, the wear volumes were assessed by optical profilometry since some scars did not met spherical caps as those occurred in hard materials. Thus, the test was effective to reproduce localized and consistent scars with micro-abrasion features by conducting short experiments, meaning it could be potentially used as an accelerated wear method for the characterization of sealing elastomers.

Comparison between PEEK and Ti6Al4V concerning micro-scale abrasion wear on dental applications

In the oral cavity, abrasive wear is predictable at exposed tooth or restorative surfaces, during mastication and tooth brushing. Also, wear can occur at contacting surfaces between the Ti-based prosthetic structures and implants in presence of abrasive compounds from food or toothpaste. Thus, the aim of this work was to compare the abrasive wear resistance of PEEK and Ti6Al4V on three-body abrasion related to different hydrated silica content and loads. Surfaces of Ti6Al4V or PEEK cylinders (8mm diameter and 4mm height) were wet ground on SiC papers and then polished with 1µm diamond paste. After that, surfaces were ultrasonically cleaned in propyl alcohol for 15min and then in distilled water for 10min. Micro-scale abrasion tests were performed at 60rpm and on different normal loads (0.4, 0.8 or 1.2N) after 600 ball revolutions using suspensions with different weight contents of hydrated silica. After abrasive tests, wear scars on flat samples were measured to quantify the wear volume and characterized by scanning electron microscope (SEM) to identify the dominant wear mechanisms. Results showed a higher volume loss rate on PEEK than that recorded on Ti6Al4V, when subjected to three-body abrasion tests involving hydrated silica suspensions. An increase in volume loss was noted on both tested materials when the abrasive content or load was increased. PEEK was characterized by less wear resistance than that on Ti6Al4V after micro-scale abrasion wear in contact with hydrated silica particles, as commonly found in toothpastes.

Wear study of Innovative Ti-Ta alloys

In this paper a wear study of innovative Ti-Ta alloys is present. Samples of Ti-30%Ta, Ti-52%Ta, were produced by laser cladding. This technology uses a high power density generated by a laser beam to melt the base material and the filler material. The interaction between the laser and the substrate is a function of the radiation absorption properties of the material and that conditions the heat flow. Laser technology allows working with high temperatures and melting powders of titanium and the alloying elements as tantalum. As this is a continuous process enables rapid cooling of the molten material and the consequent solidification. The principal importance of these innovative alloys is the low Young’s Modulus, the closest to Young´s Modulus of the bone, the biocompatibility of titanium and tantalum and consequently its applicability to biomedical industry. The wear behavior is an important factor that influences the structural integrity of materials and must be studied for innovative alloys. So in this work the micro-scale abrasive wear tests were used to characterize the wear behavior of Ti-30%Ta, Ti-52%Ta alloys. The results shows that the wear volume increases linearly as the rotation of the ball test and with the sliding distance and the analysis of the ball cratering shows that for this test there just grooving abrasion and the volume wear abrasion is higher for the highest hardness alloy.

Effect of abrasive particle size distribution on the wear rate and wear mode in micro-scale abrasive wear tests

In this work, the particle size distribution of two powders was initially analyzed, indicating an approximately normal (Gaussian) distribution with average particle size on the order of 2μm in one case and 6μm in the other. Both powders were composed of silicon carbide (SiC) particles. The two original powders were then mixed with different mass fractions, providing a series of SiC powders that were used in micro-scale abrasive tests with fixed-ball configuration. The wear tests were conducted on ASTM 1020 carbon steel and results were analyzed in terms of wear rate as well as wear mode (“rolling abrasion” or “grooving abrasion”). Results have indicated that the mass fraction of the original powders has a significant effect on the wear modes observed at the micro-scale level and that the wear rate does not follow a direct relationship with the mass fraction of the powder with larger average particle size.

Effect of test parameters on the micro-abrasion behavior of PVD CrN coatings

Micro-abrasion wear test is a widely used method in measurement of abrasive wear resistance of thin hard coatings. During the test, selection of test parameters has great importance in determination of the wear behavior of the material under investigation correctly. Therefore, in this study, the effect of test parameters on the micro-abrasion behavior of CrN coating was investigated by the fixed-ball micro-scale abrasion test and modeled by response surface methodology. The coating was deposited on AISI D2 cold work tool steel using industrial cathodic arc evaporation system. The wear tests have been performed using SiC abrasive slurry. Analysis of worn craters was conducted by scanning electron microscope (SEM). It was found that the models obtained from ANOVA tables for wear volume and wear rate of CrN coating are significant and have high correlation coefficients. The rotation speed has higher influence on the wear volume of CrN coating, whereas the normal load has higher influence on the wear rate. The higher normal load increases the wear volume and decreases the wear rate. The effect of rotation speed changes according to the value of applied speed. Grooves take place by two-body abrasion in all of the craters obtained at different rotation speed and normal load values. Depth of parallel grooves in CrN coating and AISI D2 substrate decreases with the normal load and with the rotation speed.