Emerged in the middle of 20th century, composite materials are now one of the hotspot research topics in the modern technology. Their promising characteristics make them suitable for enormous applications in industrial field such as aerospace, automotive, construction, sports, bio-medical and many others. These materials reveal remarkable structural and mechanical properties such as high strength to weight ratio, resistance to chemicals, fire, corrosion and wear; being economical to manufacture. Herein, an overview of composite materials, their characterization, classification and main advantages linked to physical and mechanical properties based on the recent studies are presented. There, were presented the conventional manufacturing techniques of composite and their applications. It was highlighted the tremendous need to discovery new generation of composites that should incorporate the synthetic or natural materials by implementing new efficient manufacturing processes. In the combination of matrix and reinforcement materials, the use of natural materials as constituent are compulsory in order to obtain a complete material degradable as environmentally friendly.

Recent progress of reinforcement materials: a comprehensive overview of composite materials

This study investigates the production of various reinforced and non-reinforced composite materials using powder metallurgy (PM). It presents the new approach into optimize the mechanical properties of hybrid composites (Al-SiC-B4C) produced with powder extrusion process. A16061 powders are used as the matrix material and B4C and SiC powders are used as the reinforcement materials. Matrix and reinforcement materials are mixed in a three-dimensional mixer. The mixtures are then subjected to cold pressing to form metal block samples. Block samples are subjected to hot extrusion in an extrusion mold after being subjected to a sintering process. This produces samples with a cross-sectional area of 25 × 30 mm2. These extruded samples were subjected to T6 heat treatment. The composite materials produced are examined in terms of density, hardness, transverse rupture strength, tensile strength, and wear resistance. Furthermore, optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and XRD are performed to examine the microstructure, surface fractures, and surface abrasion. In this study, high density Al6061/B4C/SiC hybrid composite materials were successfully produced. After extrusion, some micro particles were found to crack. The highest hardness occurred in 12%B4C reinforced composites. The lowest hardness was obtained in Al6061 alloy without reinforcement. The highest tensile strength occurred in 12%SiC particle reinforced composite material. The highest wear resistance was obtained for 9%B4C+3%SiC samples due to the hardness of B4C and the good adhesion properties of the matrix and SiC.

Wear and mechanical properties of Al6061/SiC/B4C hybrid composites produced with powder metallurgy

In recent years, many alloys as well as composites of aluminium were developed for enhanced material performance. AA 6061 is an aluminium alloy that has extensive applications due to its superior material characteristics. It is a popular choice of matrix for aluminium matrix composite (AMC) fabrication. This study provides a review on AA 6061 aluminium alloy matrix composites produced through the stir-casting process. It focusses on conventional stir-casting fabrication, process parameters, various reinforcements used, and the mechanical properties of the AA 6061 composites. Several research studies indicated that the stir-casting method is widely used and suitable for fabricating AA 6061 composites with reinforcements such as SiC, B4C, Al2O3, TiC, as well as other inorganic, organic, hybrid, and nanomaterials. The majority of the studies showed that an increase in the reinforcement content enhanced the mechanical and tribological properties of the composites. Furthermore, hybrid composites showed better material properties than single reinforcement composites. The usage of industrial and agricultural residues in hybrid composites is also reported. Future studies could focus on the fabrication of AA 6061 nanocomposites through stir casting and their material characterisation, since they have great potential as advanced materials.

A Review on AA 6061 Metal Matrix Composites Produced by Stir Casting.

In present work, Aluminium matrix composites reinforced with x wt.% SiC (x = 5, 7.5 and 10) microparticles were synthesised by powder metallurgy route. The microhardness (VHN) of the Al/SiC composites were investigated using Response Surface Methodology (RSM) and artificial neural network (ANN) approach. Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), Elemental mapping and Optical microscopy were done for the microstructural investigations. The X-ray diffraction (XRD) analysis was done for received powders and composites samples for phase recognition and existence of reinforcement particles (SiC) in the synthesised sintered composites. The design of experiments based on RSM was utilised following the central composite design method. Empirical models have been developed by considering variance analysis (ANOVA), to establish relationships among the control factors and the response variables. A feed-forward back-propagation neural network (FF-BPNN) was used to determine the qualitative characteristics of the process, and the accuracy of the BPNN system was attributed with mathematical models based on RSM model. The ANN model predicted surface hardness values are near the experimental findings. It is established that the developed models can be used to predict the hardness of the surface within the investigation range. The composite with reinforcement 7.5% revealed higher sintered density and Vickers microhardness due to the uniform distribution of filler particles in the Al matrix featuring no pores. The results indicate overall higher accuracy in the ANN method than RSM model.

Modelling and optimisation of hardness behaviour of sintered Al/SiC composites using RSM and ANN: a comparative study

Manufacturing of metal matrix composites: A state of review

Current research work emphasis on the development of rare earth particulate (REP) reinforced hybrid aluminium matrix composites processed by stir casting route. The weight percentage of CeO2 as rare-earth particulate varied from 0.5 wt% to 2.5 wt% and SiC /Al2O3 varied from 2.5 wt% to 7.5 wt%. The presence of rare earth particulate helps in grain refinement of the matrix with well defined grain boundaries is seen via Electron Backscatter Diffraction (EBSD) analysis. The Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Energy Dispersive Spectroscopy (EDS) examination were used to characterize the prepared samples of Al-6061 hybrid composites. Porosity analysis, Vickers microhardness, tensile behavior, flexural strength and impact strength of the hybrid composites improved significantly with the addition of rare earth particulate. The flexural strength of the Al-6061 hybrid composites is found to be increased upto 44.76% by increased weight percentage of rare earth oxide phase. The optimum quantity of CeO2 as RE that favours the better tribological and mechanical characteristics of aluminium hybrid composites was found to be 2.5 wt%. The results of wear tests showed an improvement of wear rate around 87.28% when compared to Al-6061 alloy with the addition of 2.5 wt% of CeO2. Finally, the worn out surface of the hybrid composites is examined with the help of scanning electron microscope to understand the wear mechanism of the composites for aerospace application.

Investigation of rare earth particulate on tribological and mechanical properties of Al-6061 alloy composites for aerospace application

Effect of RE addition on wear behavior of an Al-6061 based hybrid composite

The paper presents the study on the mechanical and microstructural behaviour of aluminium matrix hybrid composites of Al-6061 alloy with Al2O3, SiC and CeO2 as reinforcement particles processed through stir casting route. For the experimental investigations, hybrid composites were fabricated by varying weight percentages of 5,10 and 15 wt.-% of (SiC + Al2O3) mixture and weight percentage of 0.5, 1.5 and 2.5 wt.-% of CeO2 keeping total wt.-% of reinforcement less than 30 wt.-%. Mechanical properties like ultimate tensile strength, micro and macro hardness and percentage elongation were examined on the aluminium matrix hybrid composites at room temperature. The microstructure analysis was done using SEM, XRD and EDS techniques. Micro hardness value of the base alloy was increased by 17.02% on addition of 2.5 wt.-% of CeO2 as rare earth element along with (Al2O3 + SiC) mixture. In comparison to non-rare earth element (Alloy + 15 wt.-% (Al2O3 + SiC) mixture), the hardness increased by only 13.70%. Rockwell hardness of the base alloy increased by 33.80% on successful incorporation of rare earth element. The SEM microstructure analysis shows a very significant refinement of the composites after addition of rare earth particles. XRD and EDS analysis shows very good results in terms of fabrication of hybrid composite particles.

Development of rare-earth oxides based hybrid AMCs reinforced with SiC/Al2O3: mechanical & metallurgical characterization

In the current exploration, the specific wear rate of aluminium hybrid composites with traces amount of rare earth oxides (REOs) using pin-on-disc tribometer have been evaluated. For wear analysis, aluminium hybrid matrix composites (AHMCs) of Al-6061 alloy, with 2.5, 5 and 7.5 wt% of (Al2O3 + SiC) and 0.5, 1.5 and 2.5 wt% CeO2 as REOs particulate reinforcement processed through stir casting route. Hydrophobicity behaviour analysis between the aluminium liquid matrix and Al2O3/SiC reinforcement can be improved by the addition of REOs as measured in terms of contact angle by sessile drop method. For parametric study of specific wear rate using response surface methodology, four different parameters namely reinforcement with different weight percent, sliding speed, load and sliding distance have been analyzed with five different levels. The investigations shows that the quantity of reinforcement with increased amount as well as increasing sliding speed decreased the specific wear rate whereas an increase amount of load as well as sliding distance promotes the specific wear rate of AHMCs with increasing nature. But from ANOVA investigations, the effect of above parameters on sliding wear rate is totally different. It was concluded that sliding distance has more dominating impact on the wear rate of the composites with 59.94%, followed by 16.39% of sliding speed, 10.49% of normal load and 4.9% of REOs reinforcement respectively. Finally the model is validated by conducting the confirmation tests. Statistical analysis has revealed that current wear model is accurate to apply in the tribological applications.

Vipin Kumar Sharma

Papers

Investigation of rare earth particulate on tribological and mechanical properties of Al-6061 alloy composites for aerospace application

Effect of RE addition on wear behavior of an Al-6061 based hybrid composite

Development of rare-earth oxides based hybrid AMCs reinforced with SiC/Al2O3: mechanical & metallurgical characterization

Parametric study of aluminium-rare earth based composites with improved hydrophobicity using response surface method

Experimental investigation on effect of RE oxides addition on tribological and mechanical properties of Al-6063 based hybrid composites