Wear Resistance Of Aluminium Alloy Research Articles

Wear and friction behavior of Al6061 alloy reinforced with carbon nanotubes

Friction and wear behavior of Al6061 monolithic alloy and 1wt% CNTs reinforced Al6061 composite prepared through ball milling and spark plasma sintering was investigated. It was found that, under mild wear conditions, the composite displayed lower wear rate and friction coefficient compared to the monolithic alloy. However, for severe wear conditions, the composite displayed higher wear rate and friction coefficient compared to the monolithic alloy. Analysis of worn surfaces revealed that, at lower loads, abrasion was the dominant wear mechanism for both materials. At higher loads, adhesion was found to be dominant for the monolithic alloy while excessive sub-surface fracturing and delamination were mainly observed for the composite. Also, it was clarified that the friction and wear behavior of Al–CNT composites is largely influenced by the applied load and there exists a critical load beyond which CNTs could have a negative impact on the wear resistance of aluminum alloy.

The Effect of a TiN Interlayer on the Tribological Properties of Diamond-like Carbon Films Deposited on 7A04 Aluminum Alloy

Aluminum-based alloys are known to be significant candidates in the automotive and aerospace industries. However, the relatively poor wear resistance of aluminum alloys restricts their further application. In this paper, diamond-like carbon (DLC) films are deposited on the 7A04 aluminum alloy to improve its wear resistance by electron cyclotron resonance plasma-enhanced chemical vapor deposition. Before the DLC film deposition, TiN films were first fabricated as interlayer between the 7A04 aluminum alloy and DLC films by unbalanced magnetron sputtering. The influence of the TiN buffer layer on the mechanical properties of the DLC film is studied. The results showed that the TiN interlayer could provide enough mechanical support for the DLC films by suppressing plastic deformation of the aluminum alloy and then could effectively improve wear resistance of DLC films on 7A04 aluminum alloy.

Friction and wear behavior of surface nanocrystallized aluminium alloy under dry sliding condition

Abstract One way of improving the surface properties of engineering material is by reducing the grain size at the surface. Controlled ball impact process is developed for producing surface nanocrystallization and improves the surface mechanical properties by inducing compressive residual stress on the metallic materials. Improvement in the surface mechanical properties will affect the tribological properties. This paper reports the influence of the surface nanocrystallization on the tribological properties of aluminium alloy. Tribological properties were evaluated under dry sliding conditions using a reciprocating wear test facility. The friction coefficient of the treated surface is lower than that of the untreated samples and treatment improves the wear resistance of aluminium alloys. The improvement in the friction and wear properties is due to enhancement of surface strength, due to grain refinement and induction of compressive residual stress. The worn surfaces observed using scanning electron microscope reveal the dominant adhesive nature of wear and mild abrasive wear.

Improving wear resistance of aluminium alloys by developing FTC and TiC based composite coatings using plasma powder arc welding process

The aluminium alloys have enormous potentional of weight saving that are drastically gaining importance in the production of transport systems, for example, automobiles, aircraft and aerospace vehicles as well as in production of machines. Owing to the lack of sufficient abrasive wear resistance of aluminium components their application has, so far, been restricted. However, the application range of aluminium components will be extensible through the improvement of the abrasive wear resistance. The main objective of this work is the development of high wear resistant composite coatings on aluminium components by plasma transferred arc (PPA) welding. In this paper the development of the fused tungsten carbide and TiC based composite coatings with a thickness range of a few millimetres is presented. Aluminium alloys are used as matrix material and fused tungsten carbide and TiC are used as hard particles. The weldability of the powder systems with varying welding parameters is examined. The developed coating systems are tested with regard to their specific properties and their wear resistance. Finally, their application potential is presented.

Laser Cladding of Fe-Cu Based Alloys on Aluminum

For the improvement of a surface wear resistance of aluminum alloys, iron-based alloys were clad on the surface of an aluminum alloy by laser. By investigating the effect of CO2 and diode laser irradiation conditions on the formability of Fe-Cr-C clad layers, it was confirmed that the application of diode laser made it possible to obtain stable beads in low heat input compared with CO2 laser, which has been conventionally used for laser cladding. Besides, by optimizing the laser parameters, the dilution ratio of clad layers by Al substrate was minimized less than 10%. At the clad interface, the reaction layer consisting of Fe2Al5 and FeAl3 formed which caused cracks at the clad interface. Even by controlling laser conditions, this brittle layer formation could not suppressed. In this research, by using the immiscible Fe-Cu-Cr alloys as clad materials, Fe based clad layers were formed on Al substrate without any cracks at clad interface. By the effect of Marangoni motion of decomposed duplex liquid phases, Cu segregated between Al substrate and Fe based clad layers and suppressed the reaction between them.

TRIBOLOGICAL BEHAVIORS OF DUPLEX DLC/Al2O3 COATINGS FABRICATED USING MICRO-ARC OXIDATION AND FILTERED CATHODIC VACUUM ARC SYSTEM

Micro-arc oxidation technique (MAO) treatment produces a layer of alumina film on the surface of the aluminum alloy. A hard and uniform tetrahedral amorphous carbon film (diamond-like carbon, DLC) was deposited on the top of the alumina layer of the 2024 aluminum alloy by a pulsed filtered catholic vacuum arc (FCVA) deposition system with a metal vapor vacuum arc (MEVVA) source. The morphology and tribological properties of the duplex DLC/ Al 2 O 3 coating were investigated by a scanning electron microscope (SEM) and a ball-on-disk sliding tester. These results suggested that the duplex DLC/ Al 2 O 3 coating had good adhesion and a low friction coefficient, which improved significantly the wear resistance of aluminum alloys.

Wear resistance of aluminium alloy and its composites reinforced by Al 2O 3 particles

Sliding wear tests on 10, 20 and 30 wt.% Al 2O 3 particles reinforced 2024 aluminium alloy composites fabricated by a vortex method were carried out by using a pin-on-disc abrasion test apparatus where the sample slid against SiC abrasive papers of 20 (600 grit), 46 (320 grit) and 60 μm (240 grit) under the loads of 2 and 5 N at the room conditions, and the effects of sliding distance, Al 2O 3 particle content and size, SiC abrasive grit size and wear load on the wear properties of the composites were systematically investigated. For determination of the wear mechanisms of the composites, the worn surfaces were examined using scanning electron microscopy (SEM). It has been found that the wear resistance of the composites was significantly larger than that of the aluminium alloy, and increased with increasing Al 2O 3 particles content and size, and decreased with increasing the sliding distance, the wear load and the abrasive grit size. The effect of Al 2O 3 particle size on the wear resistance was more significant than that of the particle content.

Fabrication of bulk Al-La-Ni alloy by spark plasma sintering

The bulk Al85La10Ni5 alloy is sintered by spark plasma sintering (SPS) method. The microstructure and mechanical properties of the Al85La10Ni5 samples are investigated. The results show that the bulk Al85La10Ni5 alloy with less than 1.5% porosity has been obtained at 693 K. The hardness of the alloy sintered at 693 K reaches HRB 98 and the wear resistance of the alloy is twice of the conventional A390 aluminum alloy. The high wear resistance of aluminum alloy is attributed to second-phase strengthening.

IN-SITU SYNTHETIC TiB2 PARTICULATE REINFORCED METAL MATRIX COMPOSITE COATING ON AA2024 ALUMINUM ALLOY BY LASER CLADDING TECHNOLOGY

In order to improve the wear resistance of aluminum alloy, in-situ synthesized TiB 2 and Ti 3 B 4 peritectic composite particulate reinforced metal matrix composite, formed on a 2024 aluminum alloy by laser cladding with a powder mixture of Fe -coated Boron, Ti and Al , was successfully achieved using 3-KW CW CO 2 laser. The chemical composition, microstructure and phase structure of the composite clad coating were analyzed by energy dispersive X-ray spectroscopy (EDX), SEM, AFM and XRD. The typical microstructure of the composite coating is composed of TiB 2, Ti 3 B 4, Al 3 Ti , Al 3 Fe and α- Al . The surface hardness of cladding coating increases with the amount of added Fe -coated B and Ti powder which determines the amount of TiB 2 and Ti 3 B 4 peritectic composite particulate. The nanohardness and the elastic modulus at the interface of the TiB 2 and Ti 3 B 4 peritectic composite particulate/matrix were investigated using the nanoindentation technique. The results showed that the nanohardness and the reduced elastic modulus from the peritectic composite particulate to the matrix is a gradient distribution.

Microstructure and wear properties of laser cladding Ti–Al–Fe–B coatings on AA2024 aluminum alloy

In order to improve wear resistance of aluminum alloy, the in situ synthesized TiB2 and Ti3B4 peritectic composite particulate reinforced metal matrix composite formed on the 2024 aluminum alloy by laser cladding with a powder mixture of Fe coated Boron, Ti and Al was successfully achieved using 3 kW CW CO2 laser. The laser cladding coating present excellent bonding with aluminum alloy substrate. The chemical composition, microstructure and phase structure of the composite clad coating were analyzed by energy dispersive X-ray spectroscopy (EDX), SEM and XRD. The typical microstructure of composite coating is composed of TiB2, Ti3B4, Al3Ti, Al3Fe and α-Al. The surface hardness of cladding coating is increased with the amount of added Fe coated B and Ti powder which determines the amount of TiB2 and Ti3B4 peritectic composite particulate, and obviously higher than that of substrate. The wear tests were carried out using a FALEX-6 type pin-on-disc machine. The test results show that the composite coatings with the in situ synthesized TiB2 and Ti3B4 peritectic improve wear resistance when compared with the as-received Al substrate.

Laser Cladding of Fe–Cr–C Alloys on A5052 Aluminum Alloy Using Diode Laser

In order to improve a wear resistance of aluminum alloy, we proposed a diode laser cladding of iron-based alloy on the surface of an aluminum alloy. In the first part of this research, an applicability of diode laser to laser cladding was evaluated. In this experiment, irradiation conditions were varied to investigate the effect of process parameters on the formation of clad layers. From this result, application of diode laser made it possible to obtain stable beads in low heat input compared with CO2 laser, which has been conventionally used for laser cladding. Secondly, we investigated effects of the irradiation conditions on the dilution ratio and the microstructure of a Fe–Cr–C clad layer. It was confirmed that decrease in laser power and increase in traverse speed made the dilution ratio suppressed. According to the increase in aluminum content in the clad layer, the microstructure of the clad layer changed as γ(8–20%)→γ+α(10–30%)→Fe3Al(30%–). At the interface between the clad layer and the aluminum alloy substrate, the reaction layer consisting of Fe2Al5 and FeAl3 formed. The obtained complex frequently included cracks within the clad layer or in the reaction layer, each of which was caused by different factors. The cracks in the clad layer decreased with decreasing the hardness of the clad layer and formation of the ferrite in the austenite phase, which was achieved by controlling the dilution ratio and the carbon content of the cladding material. With respect to the interface cracks, it was found that the addition of copper for reduction of the thermal stress arising at the interface had a beneficial effect on suppressing the interface cracks. In the abrasion Fe–Cr–C and the Fe–Cr–Cu–C clad layers exhibited a higher wear resistance compared with the aluminum alloy.

Advanced Plasma Nitriding for Aluminum and Aluminum Alloys

Low hardness and wear resistance of aluminum alloys limit their use in practical application to automotive parts. Formation of hard aluminum nitride (AlN) layer on the surface can prolong the life time of aluminum automotive parts. Plasma nitriding was selected in the present study to form AlN layer on aluminum alloys. This processing is an environmental friendly method because of its low gas and energy consumption. Normal plasma nitriding requires long processing time to successfully form AlN layer. For advancing this surface treatment, refining microstructure and micro-alloying processes are proposed to activate the formation of AlN by plasma nitriding. Bulk Mechanical Alloying is used not only to make grain-size refinement but also to carry out micro alloying with addition of 1 mass%Ti. The formation rate of AlN layer is improved from 4.2×10−5 μm/s to 20.8×10−5 μm/s by microstructure refining. In particular, since the co-formed TiN with AlN works as a template in the initial state nitriding, the micro-alloyed aluminum can be nitrided even without pre-sputtering.

Microstructure of Al-4.3(AT.%)Cr alloy produced by laser surface alloying

Laser alloying is a particularly effective technique to improve the corrosion and wear resistance of aluminum alloys, since it combines the controlled modification of both microstructure and chemical composition to tailor surface properties to the application requirements. The authors have performed a detailed study on the preparation of Al-Cr surface alloys by laser processing and on the structure and properties of these alloys. It was found that these alloys present a relatively high hardness and good corrosion resistance and therefore, they seem to be extremely promising surface engineered materials. In this paper, the authors will concentrate on the microstructural analysis of Al-4.3 at%Cr alloy produced by laser alloying, mainly using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

Elevated temperature wear of Al6061 and Al6061-20%Al 2O 3

Both current and potential applications of particulate reinforced aluminum alloys involve components which are required to operate under sliding contact conditions at elevated temperatures. Examples include brake rotors, piston and cylinder liners in automotive engines where operating temperatures can reach 0.5--0.8 of the melting temperature of the matrix alloy. For this reason, study of the high temperature wear resistance of aluminum alloys reinforced by Al{sub 2}O{sub 3} or SiC particles is important. These studies are also of interest for the problem of die wear during hot extrusion of aluminum matrix composites and to rationalize the process of frictional welding involved in joining of the composites. Although the room temperature tribological and mechanical behaviors of aluminum matrix composites have received considerable attention, their high temperature properties have only recently started being considered. It has been shown that Al-Si-Mg (A356) alloys with or without SiC particles show a transition from mild to severe wear when a critical temperature (at about 0.4 T{sub m}, where T{sub m} is the melting temperature of aluminum) is reached as a result of frictional heating under dry sliding conditions. In this work, high temperature wear of A16061 and A16061-20%Al{sub 2}O{sub 3} was studied at temperatures between 25--500more » C. The microstructural changes that occurred during wear have been delineated in order to understand the wear mechanisms that operate at high temperatures.« less

Sliding wear behavior of SiC whisker-reinforced aluminum composite

Wear properties of SiC whisker-reinforced 2024 aluminum alloys (designated as SiCwAl) with volume fraction of whiskers ( V f) ranging from 0 to 16% produced by a powder metallurgy technique were investigated by pin-on-disk tests under dry conditions. The test materials of a disk were rubbed against a 0.45% carbon steel counterface pin at 40 N and 0.1 m s −1. The severe to mild wear transition occurred with sliding distance for the SiCw-Al composites as well as for the unreinforced matrix 2024A1. The initial sliding distance required to achieve mild wear decreased with increasing V f. In severe wear, the wear rate and the friction coefficient linearly decreased with V f because whiskers prevented propagation of the wear crack. In mild wear, the wear rate decreased with V f because the wear particles became smaller due to surface hardening. It was concluded that the SiCw reinforcement can improve the wear resistance of aluminum alloy for both severe and mild wear.

Structure and wear behavior of nitrogen-implanted aluminum alloys*

Aluminum alloys L2, LD2, LF12, LY12, and Al-4% Cu were implanted at room temperature with nitrogen ions at an energy of 80 keV and dose range of 1×1016–8.3×1017 N+ cm−2. The surface structure and chemical state of the implanted surface layer was investigated by x-ray photoelectron spectroscopy, transmission electron microscopy and transmission electron diffraction. Hardness measurements were made using a Vickers microhardness tester, and wear tests were carried out using a pin-on-disk wear testing machine. The results reveal that implanted nitrogen combines with aluminum to form AlN precipitates at room temperature and nitrogen implantation accelerates the aging process of Al-4% Cu alloys. The results also reveal that nitrogen implantation increases the hardness and sliding wear resistance of aluminum alloys. The improvements are mainly attributed to the formation of AlN precipitates.

Use of Mullite Whiskers for Aluminium Matrix Composites

A process for the synthesis of mullite whiskers by firing a mixture of kaolinite, aluminium fluorite and graphite is obtained. The mullite whiskers have bar like form with average width ranging from 0.05 to 3 μm and aspect ratio of about 20. The reinforcement with mullite whiskers results in drastical improvement in wear resistance of aluminium alloy and less attack against the counter material in comparison with silicon carbide whiskers or alumina fibers. The elastic modulus of the composite increases to a value nearly comparable to that reinforced with silicon carbide whiskers.The secondary dendrite arm spacings of aluminium alloy in the composite prepared by liquid metal infiltration technique are about half of those in the monolithic alloy. The secondary phases of aluminium alloy tend to form at the whisker surfaces due to the rejection of solute elements to last solidifying regions. No damage of whiskers that can be interpreted due to the chemical reactivity with solute elements and αAl is detected.

Abrasive wear of powder metallurgy Al alloy 6061-SiC particle composites

The effects of sintered porosity, volume fraction and particle size of silicon carbide particles (SiC p) on the abrasive wear resistance of powder metallurgy (P/M) aluminium alloy 6061 matrix composites have been studied. Aluminium alloy 6061 manufactured following the same route was also included for direct comparison. The results show that the beneficial effect of hard SiC p addition on wear resistance far surpassed that of the sintered porosity in the P/M composites. Tremendous improvements in the wear resistance of aluminium alloy can be expected by adding the SiC p reinforcements. The wear rates of composites decreased as the amount of SiC p increased. For the composites containing the same amount of SiC p reinforcements, the wear rates decreased with increasing SiC p size. Aluminium alloy composites reinforced with larger SiC p size are more effective against abrasive wear than those reinforced with smaller SiC p size. The wear rates of the P/M aluminium alloy and 10 vol.% SiC p composite were significantly affected by the aging conditions. However, for the 20 vol.% SiC p composite, and for the composites with large SiC p size, the aging effect on the wear rate of the composites was found to be small.

Some considerations towards the design of a wear resistant aluminium alloy

The properties of light weight and wear resistance seldom go together. The resistance of aluminium alloys to sliding wear could be increased by identifying the basic mechanisms of wear and the factors influencing them. As a first step towards a perspective understanding, a wear mechanism map of aluminium alloys was produced. This paper attempts to relate material properties such as hardness and toughness to the wear rate of aluminium alloys under particular load and speed conditions. Hardness seems to be important in the wear regime of equiaxed particle formation while toughness controls the delamination type of wear. The influence of microstructure on hardness and toughness and thus on the wear resistance of aluminium alloys is discussed. A processing method involving rapid solidification and mechanical alloying to achieve a very fine microstructure in aluminium alloys is outlined.

アルミニウム合金の炭素鋼に対する潤滑摩耗

The wear resistance of aluminum alloys to normalized or quenched carbon steels (0.1-0.8%C) was examined in the state of lubricating oil supplying. Wear resistance of aluminum alloys is remarkably improved by the existence of lubricant. JIS ADC12 and hypereutectic Al-Si alloys have much better wear resistance. However, the wear resistance of these alloys containing hard silicon particles is inferior to those of other aluminum alloys rubbed with normalized high carbon steel containing more than 0.45%C at a high sliding speed or high load. Low carbon steel also gives same unpreferable effect to the wear resistance of hypereutectic Al-Si alloy. Quenched carbon steel is superior to the normalized steel for wearing of aluminum alloys, and wear loss of the alloys to the quenched high carbon steel is small.