scholarly journals Micro/Nanostructure and Tribological Characteristics of Pressureless Sintered Carbon Nanotubes Reinforced Aluminium Matrix Composites

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
P. Manikandan ◽  
R. Sieh ◽  
A. Elayaperumal ◽  
H. R. Le ◽  
S. Basu

This study reports the manufacture, microstructure, and tribological behaviour of carbon nanotube reinforced aluminium composites against pure aluminium. The specimens were fabricated using powder metallurgy method. The nanotubes in weight percentages of 0.5, 1.0, 1.5, and 2.0 were homogeneously dispersed and mechanically alloyed using a high energy ball milling. The milled powders were cold compacted and then isothermally sintered in air. The density of all samples was measured using Archimedes method and all had a relative density between 92.22% and 97.74%. Vickers hardness increased with increasing CNT fraction up to 1.5 wt% and then reduced. The microstructures and surfaces were investigated using high resolution scanning electron microscope (SEM). The tribological tests showed that the CNT reinforced composites displayed lower wear rate and friction coefficient compared to the pure aluminium under mild wear conditions. However, for severe wear conditions, the CNT reinforced composites exhibited higher friction coefficient and wear rate compared to the pure aluminium. It was also found that the friction and wear behaviour of CNT reinforced composites is significantly dependent on the applied load and there is a critical load beyond which CNTs could have adverse impact on the wear resistance of aluminium.

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sakthi Sadhasivam RM ◽  
Ramanathan K. ◽  
Bhuvaneswari B.V. ◽  
Raja R.

Purpose The most promising replacements for the industrial applications are particle reinforced metal matrix composites because of their good and combined mechanical properties. Currently, the need of matrix materials for industrial applications is widely satisfied by aluminium alloys. The purpose of this paper is to evaluate the tribological behaviour of the zinc oxide (ZnO) particles reinforced AA6061 composites prepared by stir casting route. Design/methodology/approach In this study, AA6061 aluminium alloy matrix reinforced with varying weight percentages (3%, 4.5% and 6%) of ZnO particles, including monolithic AA6061 alloy samples, is cast by the most economical fabrication method, called stir casting. The prepared sample was subjected to X-ray photoelectron spectroscopy (XPS) analysis, experimental density measurement by Archimedian principle and theoretical density by rule of mixture and hardness test to investigate mechanical property. The dry sliding wear behaviour of the composites was investigated using pin-on-disc tribometer with various applied loads of 15 and 20 N, with constant sliding velocity and distance. The wear rate, coefficient of friction (COF) and worn surfaces of the composite specimens and their effects were also investigated in this work. Findings XPS results confirm the homogeneous distribution of ZnO microparticles in the Al matrix. The Vickers hardness result reveals that higher ZnO reinforced (6%) sample have 34.4% higher values of HV than the monolithic aluminium sample. The sliding wear tests similarly show that increasing the weight percentage of ZnO particles leads to a reduced wear rate and COF of 30.01% and 26.32% lower than unreinforced alloy for 15 N and 36.35% and 25% for 20 N applied load. From the worn surface morphological studies, it was evidently noticed that ZnO particles dispersed throughout the matrix and it had strong bonding between the reinforcement and the matrix, which significantly reduced the plastic deformation of the surfaces. Originality/value The uniqueness of this work is to use the reinforcement of ZnO particles with AA6061 matrix and preparing by stir casting route and to study and analyse the physical, hardness and tribological behaviour of the composite materials.


Author(s):  
F. Robbe-Valloire ◽  
R. Progri ◽  
B. Paffoni ◽  
R. Gras

Mixed lubrication is usually related to the partition of contacts, and these latter may be divided into two categories. The first includes all asperities working in thin lubricated film (physico-chemical film) conditions. This situation corresponds to local boundary lubrication and is characterised by a local friction coefficient around 0.1. The second category contains all other asperity types. Due to the existence of a thick lubricant films asperities belonging to the second category exhibit a low friction coefficient. The global tribological behaviour for a given contact, however, is function of both categories, since it involves asperities from both categories.


2004 ◽  
Vol 13 (1) ◽  
pp. 096369350401300 ◽  
Author(s):  
D. Busquets-Mataix ◽  
N. Martvnez ◽  
M.D. Salvador ◽  
V. Amigσ

Mechanical properties and tribological behaviour of AA6061 and AA7015 aluminium matrix composites reinforced with Ti3Al intermetallics have been studied. Processing of the composites consisted of a combination of powder metallurgy and extrusion techniques. High tensile strength was attained on both alloys, although composites did not improve these properties. Also ductility was impaired on composites, but values above 10% were obtained in every case. Regarding friction coefficient, all composites showed a lower value with respect to base alloys, being lower as the amount of reinforcement increased. Wear behaviour of composites was improved.


Lubricants ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 91
Author(s):  
Andreas Hausberger ◽  
Tanja Stiller ◽  
Clemens Kappl ◽  
Lars Hensgen ◽  
Florian Grün

Technical thermoplastic materials (e.g., PEEK, PPA and POM) are widely used for tribological applications combined with different filler systems (e.g., glass- or carbon fibres) because of their excellent mechanical properties. The friction and wear behaviour of thermoplastics can be specifically improved by solid lubrication systems such as graphite, PTFE and MoS2. Besides these systems, others such as WoS2 and MnS are becoming scientifically interesting. This work investigates the influence of different solid lubricants—alternative metal sulphides and polymer-based—in combination with different glass fibre contents on the tribological behaviour of unfilled PEEK and glass fibre-filled PPA. For this purpose, compounds were produced and injection-moulded into tribological test specimens that were subsequently tested. It is particularly evident for both matrix materials that the solid lubricant SLS 22 shows a 25% wear rate reduction when compared to MoS2 and, in addition, the proportion of fibre content in PPA shows an additional wear rate reduction by a factor of 10. The friction level could be kept at a similar level compared to the usually utilised solid lubricants. The investigations showed the potential use of metal sulphide filler systems in high-performance thermoplastic with enhanced tribological properties as alternatives to the well-established solid lubricants.


2019 ◽  
Vol 71 (9) ◽  
pp. 1064-1071 ◽  
Author(s):  
Alagarsamy S.V. ◽  
Ravichandran M.

Purpose Aluminium and its alloys are the most preferred material in aerospace and automotive industries because of their high strength-to-weight ratio. However, these alloys are found to be low wear resistance. Hence, the incorporation of ceramic particles with the aluminium alloy may be enhanced the mechanical and tribological properties. The purpose of this study is to optimize the specific wear rate and friction coefficient of titanium dioxide (TiO2) reinforced AA7075 matrix composites. The four wear control factors are considered, i.e. reinforcement (Wt.%), applied load (N), sliding velocity (m/s) and sliding distance (m). Design/methodology/approach The composites were fabricated through stir casting route with varying weight percentages (0, 5, 10 and 15 Wt.%) of TiO2 particulates. The mechanical properties of the composites were studied. The specific wear rate and friction coefficient of the newly prepared composites was determined by using a pin-on-disc apparatus under dry sliding conditions. Experiments were planned as per Taguchi’s L16 orthogonal design. Signal-to-noise ratio analysis was used to find the optimal combination of parameters. Findings The mechanical properties such as yield strength, tensile strength and hardness of the composites significantly improved with the addition of TiO2 particles. The analysis of variance result shows that the applied load and reinforcement Wt.% are the most influencing parameters on specific wear rate and friction coefficient during dry sliding conditions. The scanning electron microscope morphology of the worn surface shows that TiO2 particles protect the matrix from more removal of material at all conditions. Originality/value This paper provides a solution for optimal parameters on specific wear rate and friction coefficient of aluminium matrix composites (AMCs) using Taguchi methodology. The obtained results are useful in improving the wear resistance of the AA7075-TiO2 composites.


Author(s):  
Pawandeep Singh ◽  
R.K. Mishra ◽  
Balbir Singh

Abstract This study aims to investigate the tribological behaviour of lamb bone ash (LBA) and boron carbide (B4C) reinforced ZA-27 hybrid metal matrix composites fabricated using a stir casting process. The weight percentage of LBA and B4C particles in the composites were varied from 0-5 wt.%. The composites have been evaluated for density, porosity and microhardness before tribological testing. Dry sliding friction and wear behaviour of composites were studied on a pin-on-disc tribometer by varying load from 10-50 N at a fixed sliding speed of 1 m/s. Also, to investigate the effect of sliding speed on friction and wear behaviour of composites, tests were carried out at 2 m/s and 3 m/s of sliding speed. A scanning electron microscope (SEM) was used for examining the microstructure and worn surface morphology of composite samples. SEM micrographs revealed the presence and homogeneous distribution of reinforcement particles, and energy-dispersive X-ray spectroscopy (EDS) analysis confirmed the presence of LBA and B4C particles in the composites. Composites density decreased, and porosity increased with the addition of reinforcement particles. The microhardness of the 5 wt.% reinforced LBA composite improved by 18.38%, whereas hybrid composite containing (2.5 wt.% LBA + 2.5 wt.% B4C) showed an improvement of 42% compared to the base alloy. The coefficient of friction (COF) and wear loss increased with the increase in load, whereas COF decreased and wear loss increased with the increase in sliding speed. Composites showed superior wear resistance even at higher loads and sliding speeds. SEM micrographs of worn surface revealed adhesion and abrasion type of wear mechanisms. Therefore, with the improvement in wear resistance this developed composite can be used as a bearing material over monolithic ZA-27 alloy in the automotive sector.


2016 ◽  
Vol 674 ◽  
pp. 219-224 ◽  
Author(s):  
Marcin Chmielewski ◽  
Remigiusz Michalczewski ◽  
Witold Piekoszewski ◽  
Marek Kalbarczyk

In the present study, the influence of the volume fraction of graphene on the tribological properties of copper matrix composites was examined. The composites were obtained by the spark plasma sintering technique in a vacuum. The designed sintering conditions (temperature 950°C, pressing pressure 50 MPa, time 15 min) allowed obtaining almost fully dense materials. The tribological behaviour of copper-graphene composite materials was analysed. The tests were conducted using a CSM Nano Tribometer employing ball-on-plate tribosystem. The friction and wear behaviour of copper-graphene composite materials were investigated. An optical microscope, interferometer, and scanning electron microscope were used to analyse the worn surfaces. In friction zone, the graphene acts as a solid lubricant, which results in the increase in the content in the composites positively influencing the tribological characteristics of the steel- Cu-graphene composite.


2017 ◽  
Vol 2017 ◽  
pp. 1-9
Author(s):  
J. Sukumaran ◽  
R. Keresztes ◽  
G. Kalácska ◽  
H. Almaliki ◽  
P. D. Neis ◽  
...  

Polyamide (PA6/6) is often used as a tribological pair in abrasion prevalent applications such as hinges and sliders. PA6/6 is frequently processed by injection moulding and extrusion process. It is known that these processes influence the polymers mechanical behaviour, but their influence on the polymers wear response has not been studied. Hence the present research attempts to study the influence of different manufacturing processes on tribological behaviour for PA6/6. Wear tests were performed on a pin abrading tester (DIN 50322). Abrasion resistance of both extruded and injection moulded PA6/6 were tested at different loads (20 and 35 N). Single-pass (nonoverlapping mode) and multipass testing (overlapping mode) were used to understand the influence of clogging of wear debris. It is evidenced that with increasing load the specific wear rate decreases; moreover, fine abrasives tend to reduce the wear rate. In multipass testing a transfer layer clogged on the counterface that acted as a protective agent and lowers wear rate. Poor mechanical strength of injection moulded polymers is apparently compensated by microstructural response for having a similar wear behaviour between extruded and injection moulded PA 6/6. Hence a proper balance between microstructural and mechanical characteristics is an absolute must in PA 6/6 for better wear performance.


2016 ◽  
Vol 674 ◽  
pp. 181-188
Author(s):  
Maksim Antonov ◽  
Jaan Kers ◽  
Laura Liibert ◽  
Volodymyr Shuliak ◽  
Anton Smirnov ◽  
...  

Basalt reinforced composites are quite recently (during last 20 years) developed materials having low density, high specific strength, good frictional, heat and chemical resistance. Natural mineral based fibres are potential alternatives to glass fibres for their strength and to carbon fibres for their lower cost. In order to use basalt reinforced composites for lightweight applications, it is necessary to perform wear characterisation. Basalt fibre, powder and scales reinforced, unsaturated polyester and epoxy resin composites were fabricated with various ratios of basalt and polymeric matrixes. The tribological behaviour of basalt reinforced composites was determined according to the ASTM G132 standard test method for pin abrasion testing. Results showed that type and content of reinforcement have a significant influence on the mechanical and tribological properties of the composites. Scanning electron microscope images are given to illustrate the wear mechanism of composites.


2013 ◽  
Vol 371 ◽  
pp. 343-347
Author(s):  
Radu Caliman

Thanks to their low density, good thermal, mechanical and tribological properties, composites made of carbon fibres and epoxy are particularly adapted to the manufacturing of aircraft brake discs. Several methods have been developed to improve their performance. The purpose of the present study was to evaluate the influence of different epoxy/carbon fibers ratio enhance modification on the friction behaviour and to identify the related mechanisms. Nine different hybrid matrix composites were elaborated. These samples were submitted to structural and mechanical characterization, then to friction and wear tests using a pin-on-disc tribometer, at ambient temperature and humidity, constant rotating speed, varying the loading pressure. As the content of carbon fiber increased, the wear rate of the composites trended to increase. Under the friction condition of high applied load, the friction coefficient inclined to decrease while wear rate increased. When slided under a relatively high load of 12 daN, the wear resistance behaved was better as the content of carbon fiber increased. The aim of the present study was to understand the friction mechanisms of these composites, dealing with the effects of varying the carbon fiber concentration within the matrix, not only on the tribological behaviour but also on the superficial mechanical properties.


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