Dry Sliding Wear Performance Research Articles

Taguchi Grey Relational Analysis for Multi-Response Optimization of Wear in Co-Continuous Composite.

Co-continuous composites have potential in friction and braking applications due to their unique tribological characteristics. The present study involves Taguchi grey relational analysis-based optimization of wear parameters such as applied load, sliding speed and sliding distance, and their effect on dry sliding wear performance of AA6063/SiC co-continuous composite manufactured by gravity infiltration. A Taguchi L9 orthogonal array was designed and nine experimental runs were performed based on the designed experiments. The coefficient of wear and specific wear rate were recorded for each experiment. Based on the average responses computed from Taguchi grey relational analysis, an applied load of 60 N, sliding speed of 1 m/s and sliding distance of 1000 m were estimated to be the optimal parameters. An Analysis of Variance (ANOVA) was conducted to identify the predominant factor and established all the three factors as being significant. The sliding distance was found to have the highest significant influence of 61.05% on the wear of the C4 composite. Confirmation experiments conducted using the optimal parameters indicated an improvement of 35.25% in grey relational grade. Analysis of the worn surfaces of the confirmation experiment revealed adhesive and abrasive wear as the governing mechanisms.

Microstructure and dry sliding wear behavior of ultrafine-grained Co-30 at% Cr alloy at room and elevated temperatures

Co-Cr-based alloys have been widely used as mechanical components where high wear-resistance is required. However, conventional Co-Cr alloys usually have coarse-grained microstructures with phase coexistence of both hexagonal close packed (hcp) ε-Co and face-centered cubic (fcc) γ-Co. The wear resistance of the Co-Cr alloys could be further enhanced by grain refinement and exclusion of γ-phase. Here, a Co-30Cr (at%) bulk alloy consisting of ultrafine-grained matrix of ε-phase and uniformly dispersed nanoscale precipitates of σ-phase was fabricated by high energy ball milling and spark plasma sintering. Microstructure and dry sliding wear performance against alumina at room temperature and 600 °C were then investigated. The matrix and the precipitates have the average grain size of 227 nm and 16 nm, respectively. Hardness was determined to be 707 HV. The ε-Co matrix, ultrafine-grained microstructure and the uniformly dispersed nanoprecipitates enable the alloy with excellent wear resistance. Grain growth of the matrix grain was found as the key factor to be responsible for the increase of wear rate at 600 °C. Subsurface microstructures of the alloy show no significant plastic deformation after wear tests, which is attributed to high hardness of the alloy and very limited slip in hcp system.

Influence of Mo on the high temperature wear performance of NiCrBSi hardfacings

Abstract This study investigates the effect of 10 wt% Mo alloying of NiCrBSi hardfacing on the microstructure and dry sliding wear performance at room temperature and elevated temperatures up to 700 °C. Mo additions refined the boride and carbide phases in the microstructure and formed a Mo-rich boro-carbide along with a 20% drop in its hardness. It further improved the wear resistance at all tested temperatures due to the formation of Mo oxides on the worn surfaces.

Effect of Particle and Carbide Grain Sizes on a HVOAF WC-Co-Cr Coating for the Future Application on Internal Surfaces: Microstructure and Wear

The use of nanoscale WC grain or finer feedstock particles is a possible method of improving the performance of WC-Co-Cr coatings. Finer powders are being pursued for the development of coating internal surfaces, as less thermal energy is required to melt the finer powder compared to coarse powders, permitting spraying at smaller standoff distances. Three WC-10Co-4Cr coatings, with two different powder particle sizes and two different carbide grain sizes, were sprayed using a high velocity oxy-air fuel (HVOAF) thermal spray system developed by Castolin Eutectic-Monitor Coatings Ltd., UK. Powder and coating microstructures were characterized using XRD and SEM. Fracture toughness and dry sliding wear performance at three loads were investigated using a ball-on-disk tribometer with a WC-Co counterbody. It was found that the finer powder produced the coating with the highest microhardness, but its fracture toughness was reduced due to increased decarburization compared to the other powders. The sprayed nanostructured powder had the lowest microhardness and fracture toughness of all materials tested. Unlubricated sliding wear testing at the lowest load showed the nanostructured coating performed best; however, at the highest load this coating showed the highest specific wear rates with the other two powders performing to a similar, better standard.

Mechanical Behavior and Sliding Wear Studies on Iron Aluminide Coatings Reinforced with Titanium Carbide

Wear-resistant iron aluminide-based composites were coated on steel substrates with the High-Velocity Oxy-Fuel (HVOF) technique using ball milled Fe3Al and TiC powders as feedstock. The phase composition, microstructure, microhardness, elastic modulus and dry sliding wear performance of unreinforced Fe3Al and Fe3Al–TiC composite coatings (reinforced with 30 and 50 vol. % TiC particles) were evaluated in order to reveal the relationship between the mechanical and tribological behaviors. Compared to the unreinforced coatings, the composite coating with 30 vol. % TiC particles exhibited much greater hardness and higher elastic modulus. The increase of the elastic modulus of the composite coatings did not result in deterioration of sliding wear behavior. The addition of 50 vol. % TiC resulted in a further increase in hardness, however, both composite coatings showed the same elastic modulus. The fractured cross sectional surface of the unreinforced coating showed a weakly bonded microstructure promoting delamination in wear tests, whereas the composite fractured surface showed strong mechanical bonding between the matrix and carbide particles, leading to better cohesion. The Fe3Al–TiC coatings showed almost three orders of magnitude higher wear resistance under the dry sliding wear test compared to the unreinforced coatings.

Influence of Specimen Temperature on Wear Characteristics of AA6063 Aluminium Alloy

Dry sliding wear performance of aluminium alloy (AA 6063) was studied by varying applied normal load, sliding velocity and varying specimen temperatures from 50 to 150 °C. The results signify that the wear increases as the load increases from 10 to 20 N, while it decreases when the sliding velocity of the specimen increases from 1 to 2 m/s at room temperature. As the temperature of the specimen increases, the wear rate increases marginally at initial stage and then increases rapidly for a constant load and velocity. The specific wear was found to be decreased when load and sliding velocity were increased. However, in the case of varying specimen temperature condition, particularly at elevated temperature of the specimen, the specific wear showed an increasing trend. Coefficient of friction (COF) was nearly stable to both load and velocity, but it is marginally vary when temperature of the specimen increases from 50 to 100 °C and it decreases rapidly from 100 to 150 °C.

Axial suspension plasma spraying of Al2O3 coatings for superior tribological properties

Suspension plasma spray is a relatively new thermal spray technique which enables feeding of fine powder to produce advanced coatings for varied applications. This work investigates the difference in structure and performance of Al2O3 coatings manufactured using conventional micron-sized powder feedstock and a suspension of sub-micron to few micron sized powder. Axial injection was implemented for deposition in both cases. The effect of feedstock size and processing on the tribological performance of the two coatings was of specific interest. The coatings were characterized by Optical and Scanning Electron Microscopy, micro-hardness and scratch resistance testing, and their dry sliding wear performance evaluated. The suspension sprayed coatings yielded significantly higher scratch resistance, lower friction coefficient and reduced wear rate compared to conventional coatings. The improved tribological behaviour of the former is attributable to finer porosity, smaller splat sizes, and improved interlamellar bonding.

Friction-stir processing of Al–12%Si alloys: grain refinement, numerical simulation, microstructure evolution, dry sliding wear performance and hardness measurement

Friction-stir processing (FSP) has been proven as a successful method for the grain refinement of cast aluminum alloys. The most important attributes of this process are the fine-grain microstructure and characteristic texture, which impart suitable properties in the as-processed material. In the current work, FSP of Al–12%Si alloy has been carried out and the consequent evolutions of microstructure and mechanical properties have been studied. The influence of the tool rotational speed on such characteristics was also evaluated. The results showed that FSP significantly improved the microstructure of the as-cast Al–12%Si alloy by eliminating the porosity and refining both α-Al grains and the Al–Si eutectics. The microstructures favored the improvement of hardness of the processed surface layers, in comparison with those properties of the base material. Finite elements method based, 3D, thermo-mechanical model was built to better-understand the effect of process parameters on temperature gradients.

Dry Sliding Wear Performance of Al/7075/Al2O3p/Grp Hybrid Metal Matrix Composites

In this paper, the dry sliding wear performance of Alumina-Al2O3 and graphite-Gr particles reinforced with Al7075 (aluminum alloy 7075) hybrid metal matrix composites is studied by means of a pin-on-disc tribometer. Ceramic particles Al2O3 along with solid lubricant Gr are incorporated into Al7075 matrix to accomplish improvement in the wear properties such as wear and coefficient of friction. These Al7075/Al2O3p/Grp hybrid composites with varying percentages of Al2O3 and Gr are produced by stir casting method in a controlled atmosphere. Uniform distribution of reinforcing particles is confirmed by SEM views. The influence of various parameters such as Al2O3 (0 and 3 wt.%), Gr (2, 4 and 6 wt.%), applied load (10, 20 and 30N) and sliding distance (1000, 1500 and 2000m) is evaluated on dry sliding wear performance of these hybrid composites namely, wear and coefficient of friction. The wear tests are designed according to Taguchi’s L18 orthogonal array (21 x 33) to observe the wear performance of these composites during dry sliding wear tests. Analysis of variance and main effects plots are used to analyze the wear test data. It is observed that the wear is mainly influenced by the Al2O3% reinforcement and applied load. Wear decreases with the increase of Al2O3% reinforcement and increases with increase of applied load. Whereas, coefficient of friction is mainly influenced by Gr% reinforcement and the applied load. Applied load affects significantly both wear and coefficient of friction, whereas sliding distance has insignificant effect on both.

Dry sliding wear performance of nanostructured WC–12Co deposited through microwave cladding

In the present work, two WC–12Co powders with particle size in the micrometric and nanometric range were used to develop clads on austenitic stainless steel using microwave hybrid heating technique. The microstructure of the micrometric clads exhibited skeleton structured carbides distributed in the metallic matrix, while uniformly distributed clusters of nanocarbides were observed in the nanometric clad. The average microhardness of the nanometric and the micrometric clad layer was observed to be 1564±53 HV and 1138±90 HV, respectively. The nanometric clads exhibited approximately 54% higher wear resistance. This is attributed to the uniform distribution and higher volume fraction of the nanocarbides present in the clad.

Dry sliding wear performance of 7075 Al alloy under different temperatures and load conditions

Dry sliding wear tests were performed for 7075 Al alloy under a load of 25–250 N at 25–200 °C. The wear behaviors and mechanisms under various testing conditions were explored. A mild-to-severe wear transition is noticed to occur with an increase in the load at 25–200 °C. With the temperature increasing, the wear loss decreases constantly under the low load of less than 50 N. It can be suggested that the 7075 Al alloy presents a high wear resistance under a high ambient temperature and low load. Its high wear resistance is found to be attributed to the existence of mechanically mixing layer (MML). The predominant wear mechanism is adhesive and abrasive wear at room temperature. With the ambient temperature and load increasing, oxidative wear and plastic extrusive wear successively prevail due to thermal oxidation and softening of matrix.

Fabrication of Al/AlN nano-composite layers by friction stir processing of 6061 Al-T6 substrate

Friction stir processing was employed for the production of Al/AlN nano-composite layers on a 6061 Al-T6 substrate. Nano-sized AlN powder was inserted in a groove in the middle length of the substrate. Defect-free layers were achieved using tool rotation and substrate advancing speeds in the range of 900–1400 rpm and 63–310 mm/s, respectively. Subsequent passes were conducted to break-up AlN clusters that formed in a non-uniform fashion after initial pass. The grain size of aluminum matrix was found to decrease by the introduction of AlN powder. A nano-composite layer with near uniform dispersion of nano-sized AlN reinforcements with a ~9.6% volume fraction was achieved in a matrix of fine dynamically restorated Al grains with a mean size of ~2.5 µm after three subsequent passes. This layer showed an average micro hardness value of ~164 HV (much greater than ~103 HV of the underlying substrate). In addition, the nano-composite layer exhibited superior dry sliding wear performance against hardened steel compared to that of 6061-T6 substrate. Increasing tool rotation and substrate advancing speeds were found to decrease the AlN content of the processed layer possibly due to increasing in powder scattering by the pin tool. This was associated with a decrease and increase in hardness values and wear-loss data, respectively. Copyright © 2014 John Wiley & Sons, Ltd.

Dry Sliding Wear Performance of A356 Alloy with Minor Additions of Magnesium

In the present investigation, effect of minor additions of magnesium (Mg) content on the dry sliding wear behavior of A356 alloy has been reported. Alloy composition, normal pressures and sliding distances on A356 alloy has been studied. The worn surfaces were characterized by SEM microanalysis. The results indicate that, the wear rate of A356 alloy increases with increase in normal pressures and sliding distances in all the cases and decreases with 0.7% Mg addition to the A356 alloy. This is due to the change in microstructure resulting in improvement of hardness and strength of the alloy. The worn surface study indicates that, the formation of oxide layer between the mating surfaces during sliding improves sliding wear performance.

Effects of laser shock peening and groove spacing on the wear behavior of non-smooth surface fabricated by laser surface texturing

Abstract The friction coefficient and wear resistance of non-smooth surface with different conditions are studied in this work. First, the effects of groove spacing on the friction behavior and wear resistance of the non-smooth surface are investigated. Second, the effects of massive laser shock peening (LSP) impact on the dry sliding wear performance of the non-smooth surface manufactured by laser surface texture (LST) are evaluated. In addition, the worn surfaces and typical microstructure in the top surface layer of all samples were characterized by field emission scanning electron microscope (SEM) with an EDS elemental analysis and transmission electron microscopy (TEM). The influence process of groove spacing and LSP on the friction behavior and wear resistance of T9 tool steel are also analyzed and discussed.

Optimization of Wear Performance of Aa 5083/10 Wt. % Sicp Composites Using Taguchi Method

Aluminium metal matrix composite is a relatively new material that has proved its position in automobile, aerospace and other engineering design applications due to its wear resistance and substantial hardness. Need for improved tribological performance has led to the design and selection of newer variants of the composite. The present investigation deals with the study of dry sliding wear performance of Al5083-10wt. % SiC composites fabricated by Ultrasonic assisted stir casting process. Dry sliding wear tests have been carried out by using Pin-on-Disk wear test rate with normal loads of 10N, 20N, 30N, sliding distance 754 m, 1131 m, 1508 m and sliding velocity 0.42 m/s, 0.63 m/s, 0.84 m/s at constant time 30minutes. Experiments were conducted based on the plan of experiments generated through Taguchi“s technique. A L9 Orthogonal array was selected for analysis of the output. Investigation to find the influence of applied load, sliding speed and sliding distance on wear rate, during wearing process was carried out using ANOVA and regression equation were developed for 10% SiC reinforced Al-5083 AMMCs. Objective of the model was chosen as “smaller the better” characteristics to analyse the dry sliding wear resistance. In this research it is observed that applied load has the highest influence followed by sliding distance and sliding speed. Finally, the experimental results were validated by the confirmation tests.

Surface modification of Ti–6Al–4V alloy via friction-stir processing: Microstructure evolution and dry sliding wear performance

The friction-stir processing (FSP) method was employed to the surface modification of Ti–6Al–4V alloy applying different processing parameters. The defect-free friction-stir processed surface layers with ~2.5mm thickness, with final microstructures of β-regions with acicular-α and GB-α, or Martensite-α′ phase, were obtainable. The FSP processing thermal cycles, macro/micro-structures, phase evolutions, microhardness measurements, and dry-sliding wear performance of the processed surface layers were investigated. Considering to the basic laws of Ti–6Al–4V microstructure evolutions during the FSP procedures, the relations between processing parameters and produced microstructure characteristics were further elucidated. It was found that a relatively lower processing peak temperature and a fast enough cooling rate benefited the formation of the fine β-regions with ultra-refined acicular-α phase and/or even needle-typed Martensite-α′. The microstructures favored the improvement of hardness and wear performance of the processed surface layers, in comparison with those properties of the base material.

Investigation of the effect of Al-8B master alloy and strain-induced melt activation process on dry sliding wear behavior of an Al–Zn–Mg–Cu alloy

This study was undertaken to investigate the influence of Al–8B master alloy and modified strain-induced melt activation process on the structural characteristics and dry sliding wear behavior of Al–12Zn–3Mg–2.5Cu aluminum alloy. The optimum amount of B containing master alloy for proper grain refining was selected as 3.75wt.%. The alloy was produced by modified strain-induced melt activation (SIMA) process. Reheating condition to obtain a fine globular microstructure was optimized. The optimum temperature and time in strain-induced melt activation process are 590°C and 10min, respectively. T6 heat treatment was applied for all specimens before wear testing. Significant improvements in wear properties were obtained with the addition of grain refiner combined with T6 heat treatment. Dry sliding wear performance of the alloy was examined in normal atmospheric conditions. The experimental results showed that the T6 heat treatment considerably improved the resistance of Al–12Zn–3Mg–2.5Cu aluminum alloy to the dry sliding wear. The results showed that dry sliding wear performance of globular microstructure specimens was a lower value than that of B-refined specimens without strain-induced melt activation process.

Effects of deep cryogenic treatment on the dry sliding wear performance of ferrous alloys

In this study, the effects of cryogenic processing on the dry sliding wear performance and microstructural features of five common engineering materials were investigated. Significant improvements were found in the wear performance of a pearlitic low carbon steel brake material, as well as AISI A2, D6 & M2 tool steels. Optical and scanning electron microscopy of selected specimens indicated a range of changes due to deep cryogenic treatment including graphite flake degradation and pearlite refinement in cast iron and low carbon steel that was previously unreported in the literature. In tool steels, carbide precipitation and microstructural uniformity reported by other investigators was observed. Macro- and micro-hardness testing revealed no significant changes in any of the materials except for the low carbon steel tested, in which measured improvements were judged to be as a result of the refinement of the pearlite matrix due to deep cryogenic treatment.

Investigation of the effect of Al–5Ti–1B grain refiner on dry sliding wear behavior of an Al–Zn–Mg–Cu alloy formed by strain-induced melt activation process

This study was undertaken to investigate the influence of Al–5Ti–1B master alloy and modified strain-induced melt activation process on the structural characteristics, mechanical properties and dry sliding wear behavior of Al–12Zn–3Mg–2.5Cu aluminum alloy. The optimum amount of Ti containing master alloy for proper grain refining was selected as 2wt.%. The alloy was produced by modified strain-induced melt activation (SIMA) process. Reheating condition to obtain a fine globular microstructure was optimized. The optimum temperature and time in strain-induced melt activation process are 575°C and 20min, respectively. T6 heat treatment was applied for all specimens before tensile testing. Significant improvements in mechanical properties were obtained with the addition of grain refiner combined with T6 heat treatment. After the T6 heat treatment, the average tensile strength increased from 283MPa to 587MPa and 252MPa to 564MPa for samples refined with 2wt.% Al–5Ti–1B before and after strain-induced melt activation process, respectively. Dry sliding wear performance of the alloy was examined in normal atmospheric conditions. The experimental results showed that the T6 heat treatment considerably improved the resistance of Al–12Zn–3Mg–2.5Cu aluminum alloy to the dry sliding wear.The results showed that ultimate strength and dry sliding wear performance of globular microstructure specimens was a lower value than that of Ti-refined specimens without strain-induced melt activation process.

Processing and dry sliding wear performance of spray deposited hyper-eutectic aluminum–silicon alloys

The influence of spray deposition process on the refinement of silicon phase and the tribological performance of hyper-eutectic Al–Si alloys is reported in this work. Due to the rapid solidification conditions that prevail during the spray deposition process, both primary and eutectic silicon were found to be refined resulting in equi-axed morphology of the silicon phase across the matrix. The average silicon particle size increased from 7μm to 17μm with increase in the silicon content of the spray deposited alloys used for the present study. Transmission electron microscopy of the spray deposited samples exhibited sub-micron sized silicon particles of both equi-axed and acicular morphology in the aluminum matrix. Pin-on-disc wear tests were performed on the spray deposited samples, by sliding samples against hardened steel counterface for about 1000m at a speed of 0.3m/s under varied loading conditions ranging from 0.17MPa to 1MPa. Scanning electron microscopy of the wear tracks and wear debris was carried out to understand the wear mechanism. The wear performance was improved with increase in the silicon content of the alloy. The wear performance of the alloys was compared with similar alloys produced through various processing routes reported in the literature. The spray deposited alloys were observed to exhibit relatively better wear performance for the range of composition and loading conditions employed.