Aluminium Matrix Composites

This paper analyses wear behaviour of Al-Si alloy A356 (AlSi7Mg) based composite reinforced with 10 wt. % SiC, and compare it with the base A356 alloy. Composite are obtained using the compocasting procedure. Tribological testing have been conducted on a block-on-disc tribometer with three varying loads (10, 20 and 30 N) and three sliding speeds (0.25, 0.5 and 1 m/s), under dry sliding conditions. Sliding distance of 300 m was constant. The goal of the paper was to optimize the influencing parameters in order to minimize specific wear rate using the Taguchi method. The analysis showed that the sliding speed has the greatest influence on specific wear rate (39.5 %), followed by the load (23.6 %), and the interaction between sliding speed and load (19.4 %). A regression analysis and experiment corroboration was conducted in order to verify the results of the optimization. Specific wear rate prediction was done using artificial neural network (ANN).

Strict requirements that are put on mechanical constructions from the aspect of increase of exploitation periods and reduction of their weights, therefore of
their prices as well, implicate developments and applications of new composite materials with matrices of lightweight metals. Composite materials with
metal matrices are used for engine cylinders, pistons, disc and drum brakes, Cardan shafts and for other elements in automotive and aviation industry. The
most important type of metallic materials is composite materials with matrices of aluminium alloys due to a set of their beneficial properties. Improvement
of mechanical, especially tribological properties of hybrid composites were provided by the use of certain reinforce materials such as SiC, Al2O3 and
graphite in defined weight or volumetric share. New developed hybrid composites with aluminium matrices have significantly higher resistance to wear,
higher specific stiffness and higher resistance to fatigue. By the increase of quantities of produced elements made of hybrid composites, decrease of their
prices is induced that even further enlarge their applications. The applications of aluminium hybrid composites are considered from the aspect and with
the focus on automotive industry

The development of new lightweight and strong materials and the design of new products are among the key elements for the development of new advanced construction and vehicle parts for the automotive industry. The use of composite materials in the automotive industry has been popular in recent decades due to the need to reduce vehicle weight, which directly affects fuel consumption and exhaust gases emission. In this way, the development of improved new materials with improved performance is accomplished. Nanocomposites represent a new class of materials that has excellent thermal and mechanical properties. The application of nanocomposites for development of automotive components is reflected in the improvement of the production rate, environmental and thermal stability, and the reduction in weight in the automotive industry, less wear parts, and indirectly to reduce CO2 emissions and environmental pollution. This research paper presents a review of the application of nanocomposites (metal, ceramic and polymeric) in the automotive industry.

This paper presents tribological characteristics of hybrid composites with aluminium
matrix, reinforced with silicon carbide (SiC) and graphite (Gr). Newly
formed Al/SiC/Gr hybrid composites are the combination of the two different hybrid
materials. Namely, hard particles of silicon carbide increase the hardness and
resistance to wear, while soft particles of graphite improve lubrication and reduce
friction coefficient and wear. It is possible to obtain Al/SiC/Gr hybrid composites
by different methods of casting. Tribological tests show that load, sliding speed,
sliding distance, content and size of reinforcement particles influence the size
and the type of wear and friction coefficient of Al/SiC/Gr hybrid composites with
aluminium matrix.

Investigation of tribological behaviour of the hybrid composite, whose substrate is Al/Si alloy A356, reinforced with 10 wt. (%) of silicon carbide (SiC) and 0 and 5 wt. (%) of graphite (Gr) is presented in this paper by application of the Taguchi method. The composites are obtained by the compocasting procedure. The tribological investigations were realised on the tribometer with the block-on-disc contact pair in lubricating conditions and for the two values of the sliding speed, 0.25 and 1 m/s, two values of load 40 and 120 N and two values of the sliding path, 1200 and 2400 m. The wear traces were measured within the experiment, namely the wear intensities were calculated and results analysis was performed by application of the ANOVA technique. The strongest influence on the wear intensity was exhibited by the normal load (39.05%), then follow wt. (%) of the reinforcer (26.84%), the sliding speed (20.93%) and the sliding path (10.72%). The smallest wear appears in hybrid composite Al/SiC/Gr with 5 wt. (%) of the graphite reinforces, at the lowest load of 40 N, sliding speed of 1 m/s and along the sliding path of 2400 m. The main aim of their study is to provide new information and knowledge about the tribological behaviour of hybrid composites with a base of Al-Si alloy A356 reinforced with 10 wt. (%) SiC and with the addition of 0 and 5 wt.% Gr under lubricated sliding conditions.

Prediction of tribological characteristics of hybrid composites with A356 matrix using artificial neural networks (ANN) was performed in this paper. During experiment next parameters were varied: sliding speed, load, sliding distance and wt.% of reinforcement. The obtained experimental results were used to form the artificial neural network in which were varied number of neurons in the hidden layer, number of layers, the activation function and the function of training. Training of the neural network was performed for the wear rate, and optimal regression coefficient was equal to 0.994, for the network 4-15-10-1. Using neural networks to predict the wear rate greatly reduces the time and cost of experiment.

Tribological behaviour of a hybrid composite with the aluminium alloy base A356 reinforced by 10 wt. % SiC and 5 wt. % of graphite is treated in this paper. The optimization of tribological behaviour was conducted through the application of Taguchi method. Hybrid composites were obtained in the compocasting procedure. Tribological examinations were executed on the block on disc tribometer with the variation of two different load values (20 and 30 N), three sliding speed values (0.25, 0.5 and 1 m/s) and three sliding distance values (30, 90 and 150 m). All the examinations were carried out in conditions with no lubrication existing. The analysis of the wear rate was conducted using the ANOVA method of analysis. The greatest impact on the wear rate has the load (62.11 %), then the sliding speed (32.88 %), and the least the sliding distance (2.57 %). The interaction of the factors does not have a significant impact on the wear rate.

The paper presents tribological behaviour of hybrid aluminium composite A356/10SiC/3Gr in dry-sliding conditions. Hybrid
composites were made with a modified compocasting procedure and tribological tests were conducted on a tribometer with a
block-on-disc contact geometry. An analysis of the effects of three sliding speeds ((0.25, 0.5 and 1) m/s) and two normal loads (10 N and 20 N) on the wear volume and wear rate was conducted for different sliding distances. The total sliding distance was
300 m. SEM and an EDS analysis of the wear surfaces of the tested material were also performed. The analysis of the wear
surfaces shows an intensive adhesive wear of hybrid composites. Also, the appearance of mechanically mixed layers (MMLs) was confirmed, i.e., an increase in the concentration of iron in the hybrid composite material.

In situ composites are a class of composite materials in which the reinforcement is formed within the matrix by reaction during the processing. In situ method of composite synthesis has been widely followed by researchers because of several advantages over conventional stir casting such as fine particle size, clean interface, and good wettability of the reinforcement with the matrix and homogeneous distribution of the reinforcement compared to other processes. Besides this, in situ processing of composites by casting route is also economical and amenable for large scale production as compared to other methods such as powder metallurgy and spray forming. Commonly used reinforcements for Al and its alloys which can be produced in situ are Al2O3, AlN, TiB2, TiC, ZrB2, and Mg2Si. The aim of this paper is to review the current research and development in aluminum-based in situ composites by casting route.

In present study, the tribological behavior of hybrid composites with A356 aluminum alloy matrix reinforced with 10 wt.% of SiC and 5 wt.% of graphite was investigated using the Taguchi method. The composites were produced by the compocasting procedure. The tribological properties were studied using block-on-disk tribometer under lubricated sliding conditions at different normal loads (40N, 80N and 120N), sliding speeds (0.25 m/s, 0.5 m/s and 1 m/s) and sliding distances (150 m, 300 m and 1200 m). Analysis of the wear rate results was performed using the ANOVA technique. The lowest level of wear rate corresponded to the contact conditions with normal load of 40N, sliding speed of 1.0 m/s and sliding distance of 1200 m.

Spur gears are the simplest type of gears, which are widely used in modern structures. One of the main tasks of researchers in application areas of gears within the responsible structures, especially in spacecraft propulsion mechanisms, is to obtain compact gear, small size and weight, while maintaining or improving functional characteristics. Therefore there was a need to explore new materials that could be used as a replacement for steel in the manufacturing of gears. A good alternative for steel is hybrid composite with aluminum matrix and various reinforcements, which provides adequate mechanical properties, while reducing the weight of the gear. The paper presents the modeling of gears and analysis of their stress-deformation state using the finite element method. Steel and composite gears made from aluminum matrix with various reinforcements were tested. Results from this study show that the gear made of composite material offers enhanced features compared to metal gears.

Aluminium matrix composites (AMCs) are a range of advanced engineering materials that can be used for a wide range of applications within the aerospace, automotive, biotechnology, electronic and sporting goods industries. AMCs consist of a non-metallic reinforcement (SiC, B 4 C, Si 3 N 4 , AlN, TiC, TiB 2, TiO 2 ) incorporated into Aluminium matrix which provides advantageous properties over base metal (Al) alloys. These include improved abrasion resistance, creep resistance, dimensional stability, exceptionally good stiffness-to-weight and strength-to-weight ratios and better high temperature performance. Fabrication of these advanced engineering materials through liquid state and solid state routes are considered in this paper.

This paper presents basic tribological properties of A356/10SiC/1Gr hybrid composites in conditions with lubrication. Hybrid composite specimen is obtained by compocasting procedure. A356 aluminium alloy is used as a base matrix alloy, reinforced with 10wt% of SiC and 1wt% of graphite. Tribological
tests are done on advanced and computer supported tribometer with block‐ondisc contact pair. By the experimental plan, test is conducted under three different values of sliding speed, three different values of normal load, different sliding distances, and also different lubricants. SEM and EDS are used for wear analysis. The analysis has shown the presence of MML, which means that there was transfer of material from steel disc to composite block.

In this paper in depth review of aluminium matrix material with different particle size reinforcement is explored. Metal matrix composites are important class of novel engineering materials used in different applications because of their lower density, higher specific strength and better physical and mechanical properties. Aluminium alloy based metal matrix composites (AMMC) are widely used for sliding wear applications because of their excellent wear resistant properties. They are widely used in Aerospace, Defense, Automobile, Marine industries, etc. due to their excellent mechanical properties. Engine Pistons are commonly made of a cast aluminum alloy for excellent thermal conductivity and light in weight. The continuous development of modern fuels leads to specific objectives for further piston development in the field of reduction of piston weight, increase of mechanical and thermal load capacity and lower friction etc. New compositions of aluminium materials have to be studied so that to meet the development of new kind of fuels. [1-5] The Aluminium matrix is strengthened when it is reinforced with hard particles like SiC, Al 2 O 3 , B 4 C, CNT, Graphene etc. resulting in enhanced wear resistance and improved strength to weight ratio. Based on the type of reinforcement, size and morphology, The AMCs are fabricated by different methods like powder metallurgy, stir casting, squeeze casting etc. In this paper an attempt is made to review micro and nano particle reinforced aluminium matrix composite.

MMCs as new and promising materials are under constant development and their application in different industries is increasing. They have better mechanical and tribological properties comparing to the matrix materials. This paper presents tribological tests results of Al-Si alloy A356 (EN-Al Si7Mg0.3), with and without 3 wt. % Al2O3 reinforcement. The reinforcement was in the shape of particles with 12 μm in diameter and the technology for producing of composite was compocasting. The pin-on disc tribometer was used to carry out these tests under dry sliding conditions at different loads. Worn surfaces and wear debris were also observed and analysed with scanning electron microscopy (SEM).

Friction stir processing (FSP) has evolved as an important technique in fabrication of metal matrix composites. The surface properties enhancement is obtainable by insertion of desired discontinuous particular reinforcements into base alloy using FSP. Despite having high specific strength, more applications of Al alloys are restricted due to their poor surface properties under various loading conditions. In this study, the main focus is on enhancing the microhardness and wear properties of Al 7075 base alloy by means of uniform dispersion of silicon carbide and graphite (SiC/Gr) nano particles into the base alloy using the FSP technique. The tool rotational speed (w: 500, 1000, 1500 rpm), tool traverse speed (v: 20, 30, 40 mm/min), reinforcement particles hybrid ratio (HR: 60:40, 75:25, 90:10) and volume percentage (vol%: 4%, 8%, 12%) are used as independent parameters. The effect of these parameters on microstructure, micro hardness and wear properties of surface composites are studied in detail. For desired wear rate and microhardness as responses, the aforementioned independent parameters are optimized using response surface methodology (RSM). The significance of factors and their interactions for maximizing hardness and minimizing wear rate and coefficient of friction (COF) were determined. Analysis of variance (ANOVA) for responses has been carried out, and the models were found to be significant in all three responses. The minimum wear rate of 0.01194 mg/m was obtained for parameters w 1500 rpm, v 40 mm/min, HR 60:40, vol% 4 (Run 10). The maximum micro hardness of 300 HV obtained for parameters w 1000 rpm, v 30 mm/min, HR 75:25, vol% 12 (Run 14). The presence and uniform distribution of SiC and Gr into the base alloy was confirmed through field-emission scanning electron microscopy (FESEM) imaging, energy-dispersive X-ray spectroscopy (EDX) and mapping tests. The wear rate and COF decreased significantly due to graphitized mechanically mixed layer developed at the sliding contacts. The microhardness of resultant composites observed to be dependent on effect of the independent parameters on extent of inherent precipitates dissolution and grain size strengthening in the resultant materials.

Al7075 is used in automobile industries because of its lower weight to strength ratio. Aluminium metal matrix composites (AMCs) are the competent material in the industrial world due to its excellent mechanical properties. Powder metallurgy processing is the one of the most effective methods for manufacturing the composites with high volume of reinforcement. The present study is dealt with the hybrid composites (Al7075+SiC+Fly ash) through powder metallurgy technique. This hybrid composite having with various weight percentages of SiC& Fly ash particles morphology can be seen with the help of micro structural examine. The mechanical properties such as Hardness, Impact strength, micro structure were studied and reported with the increase in weight percentage of SiC & Fly ash in the Aluminium metal Matrix. Aluminium hybrid composites are a new generation of metal matrix composites that have the potential of satisfying the recent demands of advanced engineering applications. The major techniques for fabricating these materials are briefly discussed and research areas for further improvement on Aluminium hybrid composites are suggested.

A comparison between TiO2 nanofibers and carbon nanofibers as fibers reinforced metal matrix composites with respect to mechanical properties improvements have been made in this paper. Al and Mg have been chosen as metal matrices. The used carbon and ceramic nanofibers (Titanium Oxide) were successfully synthesized using electrospinning technique. Various weight percentage of calcined electrospun TiO2 and carbon nanofibers (1, 3, 5 and 10%) were mixed with metal matrix and fabricated by route of powder metallurgy using High Frequency Induction heat Sintering (HFIHS). Mechanical properties of the sintered composites have been investigated. The manufactured pellets were tested for compression test, hardness and microstructures by the field emission scanning electron microscopes (FESEM), which reveals the homogeneous distribution of nanofibers in the Al/Mg matrices. In addition, energy-dispersive X-ray spectroscopy (EDS) was employed to obtain the chemical analysis of each composite. The result shows that, the ultimate compressive strength increased to 415 MPa at 5% TiO2, which is 13.5% more than the pure Al. The hardness increased up to 64% in case of using the ceramic nanofibers as reinforcement. While using CNFs as reinforcement to the Al matrix deteriorates the mechanical properties.

This study has been carried out to reinforce the commonly believed fact that the dispersion of carbon nanotubes in a composite has a profound effect on the properties of the composite. In this study, ball milling was carried out using two different parameters to obtain distinctly different degrees of dispersion of carbon nanotubes (4 wt.%) in Al-9 wt.% Si powders. Composite disks, 80 mm in diameter, having good and bad dispersions of carbon nanotubes were obtained by hot pressing. Optical micrographs and Raman spec-troscopy images showed the presence of larger carbon nanotube clusters in the bad dispersion sample. Transmission electron microscopy images confirmed the presence of large clusters in the bad dispersion sample, while the good dispersion sample showed individual carbon nanotubes in the Al matrix. Nanoin-dentation results indicated a 41% increase in the hardness and a 27% increase in the elastic-to-plastic work ratio, while compression tests indicated a 185% increase in compression yield strength and a 109% increase in fracture strength with improvement in carbon nanotubeÕs dispersion.

In this experimental study, a cylinder of aluminium metal matrix composite (AlMMC) consisting of 6061 matrix alloy and 15 wt.% (12.93 vol.%) silicon carbide (SiC) particulate reinforcement was joined by transient liquid phase diffusion bonding (TLPD) process using a mixture of silver and copper powder in a definite ratio. Four SiC reinforced AlMMC cylinders with a diameter of 15mm and a height of 10mm each was to be joined using a mixture of 59.5989mg of silver and 28.2620mg of copper as the interlayer at 520°C with a holding time of 9 hours to form two cylinders of 15mm diameter and 20mm height (approx.) with an interlayer of 50μm. Then one of the sample was tested for shear and the other was used for metallography. Abstract-In this experimental study, a cylinder of aluminium metal matrix composite (AlMMC) consisting of 6061 matrix alloy and 15 wt.% (12.93 vol.%) silicon carbide (SiC) particulate reinforcement was joined by transient liquid phase diffusion bonding (TLPD) process using a mixture of silver and copper powder in a definite ratio. Four SiC reinforced AlMMC cylinders with a diameter of 15mm and a height of 10mm each was to be joined using a mixture of 59.5989mg of silver and 28.2620mg of copper as the interlayer at 520°C with a holding time of 9 hours to form two cylinders of 15mm diameter and 20mm height (approx.) with an interlayer of 50μm. Then one of the sample was tested for shear and the other was used for metallography.

Purpose: The aim of this paper is to present a modern manufacturing method of production and compare the thermal, mechanical, properties of composite materials with aluminium alloy matrix reinforced by Al 2 O 3 particles. Design/methodology/approach: The material for investigation was manufactured by the method of powder metallurgy (consolidation, pressing, hot concurrent extrusion of powder mixtures of aluminium EN AW-AlCu4Mg1 (A) and ceramic particles Al 2 O 3). The amount of the added powder was in the range of 5 mass.%, 10 mass.% and 15 mass.%. Findings: The received results concerning the enhancement of hardness, which show the possibility of obtaining the MMC composite materials with required microstructure, influencing the properties of the new elaborated composite materials components. Concerning the thermal properties, especially the linear thermal expansion coefficient was measured, as well as the dilatometric change of the sample length was analysed. Practical implications: Concerning practical implications it can be stated that the tested composite materials can be applied among others in the transportation industry, but it requires additional research. Originality/value: The received results show the possibility of obtaining new composite materials with controlled and required microstructure with possible practical implications.

The paper presents the results of tribological tests conducted on an A339/SiC/10p composite reinforced with SiC particles. The test method used in the research was the ball-on-disc method combined with variable abrasion test parameters. Different materials were used for the counter-specimen (steel, Al2O3, SiC), variable load (5 and 10N) and sliding speed (0.1 and 0.5 m/s). It was found that the use of a counter-specimen made from a material of higher hardness significantly reduced the friction coefficient and the specific wear rate of the tested A339/SiC/10p composite. On the other hand, in all the friction pairs, an increase in the load while maintaining the same test conditions caused a decrease in the friction coefficient value and an increase in the specific wear rate. Additionally, in the Al2O3 counter-specimens, an abnormal decrease in the friction coeffi- cient was observed with an increasing load, but it had no impact on the results of the specific wear rate

We report a study of the structure-processing-property relationships in a high strength Al 93 Fe 3 Cr 2 Ti 2 nano-quasicrystalline alloy and composites containing 10 and 20 vol% ductilising pure Al fibres. The superimposed contributions of several different strengthening mechanisms have been modelled analytically using data obtained from systematic characterisation of the monolithic alloy bar. An observed yield strength of 544 MPa has been substantiated from a combination of solid solution strengthening, work hardening, precipitation hardening and Hall-Petch grain size dependent effects. These materials have been shown by other authors in previous published work to be highly sensitive to the size distribution of particles in the powder from which they are made, and the subsequent thermomechanical processing conditions. The processing condition employed in this study provided micron-sized grains with a strong [111] preferential orientation along the extrusion direction and a bimodal size distribution of the icosahedral nano-quasicrystalline precipitates. Both were deemed to be a significant contributor to the high yield strength observed. The addition of pure Al fibres was found to decrease the yield strength linearly with increasing Al content, and to augment the ductility of the composites.

Problem statement: Aluminium Matrix Composites (AMCs) has provided the potential applications in aerospace and automotive industries owing to their superior strength to weight ratio. Commercial Al and fly ash particles are chosen as matrix and reinforcement material respectively to produce composites by stir casting process. Achieving homogeneous distribution of reinforcement within the matrix is one such challenge in the stir casting process, which affects directly on the properties and quality of composites. In this research, an attempt has been made to study the influence of weight percentage of fly ash, wetting agent magnesium and the impeller model on the mechanical properties and achieving the effective flow pattern to uniformly disperse the fly ash particles in the molten Al matrix through modified two step stir casting method. Approach: Optimum parameters were identified for attaining the maximum mechanical properties such as hardness and tensile strength of composites by the application of Taguchi method, Analysis of Variance (ANOVA).Results: It was found that the optimum parameters were weight percentage of fly ash (15%) and weight percentage of Mg (1.5%), impeller model (Radial ) for the tensile strength of composite materials and weight percentage of fly ash (20%) and weight percentage of Mg (1.5%), impeller model (Radial ) for the hardness of composite materials. validated The results were validated by the confirmation test. The microstructure of the produced composites was examined by scanning electron microscope. Conclusion: The proposed results would be useful for the industrial preparation of the metal matrix composites through stir casting method.

The brake system is an important part of an automobile. It plays a vital role in helping the driver to reduce the speed of an automobile or to stop the automobile. Initially, when automobiles were first introduced, they were equipped with drum brakes. These drum brakes were cheap, easy to install and atmospheric agents cannot hinder their performance. Despite these advantages, the major disadvantage of the drum brake system is the poor heat dissipation. To tackle this problem, the automotive engineers came up with the disc brake system. The brake rotor is one of the most critical components of the disc brake system. The brake rotor is made up of a pure metal or a metal with certain reinforcements. These brake rotors are circular with perforations made in a particular manner to enable faster dissipation. These perforations help to reduce the weight of the disc brake rotor. The disc brake rotor is fixed to the wheel hub with brake calipers. In this review article, I will be critically analyzing various research articles on the thermal and mechanical properties of various brake rotor materials used in automobiles.

In the present study, a mathematical model is proposed for the prediction of wear rate of Al-12.6Si alloybased composites reinforced with in situ TiB 2 (2, 3, 5 wt%) particles by halide salt reaction route. For deducing an empirical relationship for wear rate (pin-on-disc type wear), a multiple regression analysis has been performed to show its dependency on the TiB 2 content of composite and various wear test parameters. From the regression statistics, it is inferred that the wear rate is strongly dependent on the rotating speed of the disc but moderately on the TiB 2 content and applied normal load.

In present study, the tribological behavior of hybrid composites with A356 aluminum alloy matrix reinforced with 10 wt% of SiC and 3 wt% of graphite was investigated using the Taguchi method. The composites were produced by the compocasting procedure. The tribological properties were studied using block-on-disk tribometer under unlubricated sliding conditions at different normal loads (40N, 80N and 120N), sliding speeds (0.25 m/s, 0.5 m/s and 1 m/s) and sliding distances (150 m, 300 m and 1200 m). Analysis of the wear rate results was performed using the ANOVA technique. The highest influence on wear rate was obtained for sliding distance (39.44%). The influence of normal load and sliding speed was 27.96% and 14.12%, respectively. The lowest level of wear rate corresponded to the contact conditions with normal load of 40N, sliding speed of 1.0 m/s and sliding distance of 1200 m.

The development of new lightweight and strong materials and the design of new products are among the key elements for the development of new advanced construction and vehicle parts for the automotive industry. The use of composite materials in the automotive industry has been popular in recent decades due to the need to reduce vehicle weight, which directly affects fuel consumption and exhaust gases emission. In this way, the development of improved new materials with improved performance is accomplished. Nanocomposites represent a new class of materials that has excellent thermal and mechanical properties. The application of nanocomposites for development of automotive components is reflected in the improvement of the production rate, environmental and thermal stability, and the reduction in weight in the automotive industry, less wear parts, and indirectly to reduce CO 2 emissions and environmental pollution. This research paper presents a review of the application of nanocomposites (metal, ceramic and polymeric) in the automotive industry.

Plasma electrolyte oxidation (PEO) and anodizing coatings were produced on 7075 Al alloy and compared together. Surface and cross section morphology of the coatings were studied by field emission scanning electron microscope. Phase compositions of coatings were analyzed by the X-ray diffraction Technique. Tafel polarization and immersion tests were done in 3.5.%wt NaCl solution to evaluate the corrosion properties of the coatings and substrate. The antibacterial activity of coatings was evaluated against E. coli bacterium. The PEO and anodized coatings had a completely different surface morphology and microstructure. The PEO coating was not affected by substrate surface features. Coatings cross sectional analysis showed that PEO coating had a dense barrier inner layer and a porous outer layer and it was less uniform in thickness than anodized coating. X-ray diffraction patterns of coatings demonstrated that PEO coating is mainly consisted of a crystalline γ-Al2O3 phase, while in the case of anodized coating no crystalline phase was observed which suggested that it composed of an amorphous phase. Corrosion resistance of 7075 Al alloy were improved after both coating treatments but PEO coating exhibited superior corrosion properties compared to anodized coating because of the crystalline barrier layer. Also, the presence of Silicon in PEO coating resulted in better antibacterial activity than anodized coating.

Within the last few decade there has been a rapid
growth in the application of aluminum-silicon alloys,
particularly in the field of automotive and aerospace
industries, due to their high strength to weight ratio, good
corrosion resistance, less density, better wear resistance and
low coefficient of thermal expansion. Due to this
advancements it is mandatory ot study of the mechanical
behaviour such as hardness, tensile strength and density are
most important. In this current research, Aluminum matrix
which containing 12% (weight percentage) of Silicon were
synthesized using stir casting method. Chemical composition
analysis and mechanical properties of the samples with
different composition have shown near uniform dispersion of
Silicon in the prepared alloys. The idea behind this work is to
see the effect of addition of magnesium for there finement of
microstructure.