scholarly journals Influence of Reinforcements and Heat Treatment on Mechanical and Wear Properties of Al 7075 based Hybrid Composites

2014 ◽  
Vol 5 ◽  
pp. 508-516 ◽  
Author(s):  
M. Sreenivasa Reddy ◽  
Soma. V. Chetty ◽  
Sudheer Premkumar ◽  
H.N. Reddappa

In this work, dry sliding wear properties of Al 7075 Al 7075+ 5 wt.% SiC, Al7075 + 5 wt.% SiC + X wt.% graphite (X=5-10) hybrid nano-composites were developed by the principle of powdered metallurgy (P / M). Al 7075 hybrid nano-composites are highly promising materials that would be desirable for a wide range of applications. Under dry sliding conditions, the tests were carried out on a pin-on-disk machine was used to assess the loss of wear on base metal, composite and hybrid composites were calculated by different normal loads (5–20 N), and sliding speeds (0.5 – 2 m/s) and sliding distances (500–2000 m). Micro-structural examination of base metal and composites were investigated using an Optical Microscope (OM) and scanning electron microscope (SEM). The hybrid nano-composites revealed those greatest improvements in tribological results with 5 wt. % Silicon Carbide and 10 wt. % Graphite. Main wearing mechanism for hybrid composite materials has been established to form lubricating layer on both the surface and specimen. From experimental outcomes, it has been found that wear resistance tends to increase as weight percentage of the reinforcement increases.


The metal matrix composite strengthened with ceramic material of carbide (SiC) has smart mechanical characteristics. Metal-based composites, however, demand progress in their friction and tribological characteristics. In this work-study an effort is made to design a completely new material through the method of metallurgy by adding graphite, which acts as a solid lubricant. This study explored the effect of graphite on the tribological behaviour of hybrid composite Al 7075/5 wt. % SiC / X wt. % graphite (X=10, 5 and 0). The research confirms the performance of wear properties by incorporating graphite into the composite. The sic-graphite reinforced Al 7075 (aluminium alloy 7075) was studied. Metallurgy route was used to prepare the composites. Microstructures, the mixture of materials, wear and wear resistance properties were analyzed by optical micro cope and scanning electron microscope, XRD, and pin-on-disc apparatus. The freshly developed metal composite has significant improvement in tribological properties with a mixture 5% silicon carbide (SiC) and 5% graphite. The experimental investigations confirm that a sliding distance of one thousand meters and a sliding velocity of 1.5 m / s with an applied load of 5 N leads to minimum wear loss of 0.01062g and coefficient of friction as 0.1278


Author(s):  
Prof Maibusab ◽  
H K Shivanand ◽  
Madhu M. G. ◽  
Shivaraj H.A. ◽  
Sumana B. G.

This research work investigated the in?uence of graphite powder on the wear behavior of Al 7075/Graphite Powder (Gr)/Bagasse ash (BA) hybrid composite. The investigation reveals the effectiveness of incorporation of graphite powder in the composite for gaining wear reduction. The Al 7075 (Aluminium alloy 7075) reinforced with graphite powder and Bagasse ash were investigated. The conventional liquid casting technique was used for the fabrication of composite material and subjected to T6 heat treatment. The reinforcement content was chosen as 1, 3, and 5wt. % of graphite powder to identify its potential for self-lubricating property under dry sliding conditions. Hybrid composite is processed at 1wt% of Gr with 2, 4 and 6wt% of BA. The effect of load on dry sliding wear rate and coefficient of friction performance of Al 7075 casting alloy and its composites was evaluated by using a pin-on-disc with two different loads with constant speed at room temperature. Wear tests were conducted by using pin on disc apparatus to evaluate the tribological behaviour of the composite and to determine the optimum content of graphite powder for its minimum wear rate. The wear rate decreases with addition of graphite powder content and reaches its minimum at 5wt. % graphite. The coefficient of friction decreases with addition of graphite content and was found to be minimum at wt. 5% graphite. The wear properties of the hybrid composites containing graphite exhibited the superior wear-resistance properties.


Author(s):  
H. Sh. Hammood ◽  
S. S. Irhayyim ◽  
A. Y. Awad ◽  
H. A. Abdulhadi

Multiwall Carbon nanotubes (MWCNTs) are frequently attractive due to their novel physical and chemical characteristics, as well as their larger aspect ratio and higher conductivity. Therefore, MWCNTs can allow tremendous possibilities for the improvement of the necessarily unique composite materials system. The present work deals with the fabrication of Cu-Fe/CNTs hybrid composites manufactured by powder metallurgy techniques. Copper powder with 10 vol. % of iron powder and different volume fractions of Multi-Wall Carbon Nanotubes (MWCNTs) were mixed to get hybrid composites. The hybrid composites were fabricated by adding 0.3, 0.6, 0.9, and 1.2 vol.% of MWCNTs to Cu- 10% Fe mixture using a mechanical mixer. The samples were compressed under a load of 700 MPa using a hydraulic press to compact the samples. Sintering was done at 900°C for 2 h at 5ºC/min heating rate. The microscopic structure was studied using a Scanning Electron Microscope (SEM). The effect of CNTs on the mechanical and wear properties, such as micro-hardness, dry sliding wear, density, and porosity were studied in detail. The wear tests were carried out at a fixed time of 20 minutes while the applied loads were varied (5, 10, 15, and 20 N). SEM images revealed that CNTs were uniformly distributed with relative agglomeration within the Cu/Fe matrix. The results showed that the hardness, density, and wear rates decreased while the percentage of porosity increased with increasing the CNT volume fraction. Furthermore, the wear rate for all the CNTs contents increased with the applied load.


1999 ◽  
Author(s):  
Catherine R. Wong ◽  
Lee S. Mastroianni
Keyword(s):  

Author(s):  
V Vignesh Kumar ◽  
K Raja ◽  
T Ramkumar ◽  
M Selvakumar ◽  
TS Senthil Kumar

The research article addresses the reciprocating wear behaviour of hybrid AA7075 reinforced with boron carbide and boron nitride through a stir-casting technique. The experiment involved varying wt.% of the secondary particle boron carbide (3, 6 and 9) while boron nitride (3) was kept as constant. The hybrid composites were characterised using scanning electron microscopy coupled with energy dispersive spectroscopy. The hardness and tensile behaviour of the hybrid composites were evaluated. Reciprocating wear behaviour of the hybrid composites were examined using a tribometer by varying the wear parameters such as load and sliding distance. The results revealed that AA7075/6boron carbide/3boron nitride had better hardness, tensile and wear properties. The surface morphology of the wear samples was analysed using SEM.


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