Aluminium matrix composites

Discuss about hte Metal Foams Matrices of Aluminium Composites.

Aluminium composites consist of aluminium which is reinforced with other metals with an aim to improve upon the properties of the metal. Metal foams can be produced from Aluminium composites to further enhance its properties which widens its application. This section of the research explores the properties of these metal foams of aluminium composite, various methods that are used for producing them, and the applications of the same.

Aluminium matrix composites (AMCs) are the aluminium metals reinforced with other metals or compounds for improving properties of aluminium. Different reinforcements have different impacts on the composites. Carbide (SiC), Boron Carbide (B4C) and Aluminium Oxide (Al₂O₃) are two most commonly used reinforcements. SiC increases the hardness, density and tensile strength of aluminium, B4C increases its hardness and Al₂O₃ gives it a good compressive strength and wear resistance.  They can improve the strength, stiffness, and fatigue properties of aluminium. AMCs have many applications because of their physical and mechanical properties (Ramnath, et al., 2014).

Metal foam consists of a metal which is filled with gas in its pores that form a large portion of the metal. The gas either seals the pores in which case it is called closed-cell foam or is interconnected which is called open-cell foam. A metal foam matrix would be the aluminium composite having pores filled with gas. Metal foams retain some of the metal properties like its flammability and thermal expansion coefficient while others are modified such as thermal conductivity.

Foams initially used micro-sized ceramic particles to promote stability in metals and to avoid non-uniform pore formation but now, a liquid or gas is used for stabilizing bubbles and increasing the viscosity. Ceramic particles could prevent the melted metal drain and bubble formation that commonly cause non-uniformity in structures. Presence of ceramic particles at the gas or liquid interface can retard liquid flow out of the metallic form to stop bubbles growth and make the composite structure more uniform. Ceramic particles are used in foams for minimizing their structural defects (Duarte & Ferreira, 2016).

Foaming of aluminium or its alloys can be done using a variety of production methods that include gas injection, using blowing agents, solidification, use of powder compacts, or foaming of ingots. Foaming of Aluminium melt by gas injection melting of aluminium to form metal-matrix composite and then injection of gas like nitrogen or argon through the use of vibrating nozzles or rotating impellers. In this process, fine gas bubbles are formed in the melt and the resulting mixture floats up on the liquid surface resulting into the formation of a dry liquid foam after draining out of the liquid metal. The melts can also be foamed using blowing agent that is added to melt and which gets decomposed because of heat propelling the foaming process. Melt is stirred to reach a level of viscosity. A typical foaming process lasts for 15 minutes (Banhart, 2000).

Production methods of metal foams

Gas-Solid Euclectic Solidification is a relatively new method of foaming aluminium in which aluminium is melted under high pressure and is charged with hydrogen. When temperature is lowered, the melt goes into an eutectic transition. As it solidifies, the pores of gas precipitate and get trapped inside the metal. Foaming with powdered compacts involve mixing of metal powders with blowing agents after which the compact is created from the mix forming a dense foam (Han, et al., 2015).

Foaming of ingots involve a powder-compact melting process in which titanium-hydride particles are pushed into aluminium for preparing the foamable material using a die cast material. The resulting cast resulting from foamcasting is then added with powder with slow stirring creating stable foams, a process which is called formgrip. Different rates of heat produce different varieties of pore structures (Bodunrin, et al., 2015).

Mostly, foams use closed-cells and thus, they are very useful load bearing and structural applications. Metal foams can have three types of applications including lightweight construction, energy absorption, and automotive industry. It is used in construction because its mechanical stiffness is high. High compressive strength and high impact-energy absorbing capability make metal foams ideal for acoustic and thermal control applications. In automotive industry, these foams are used three dimensional sandwich panels. They can replace conventional stamped steel in cars to reduce car frame, improve performance, reduce costs, and facilitate car assembly (Güner, et al., 2015).

AMCs are mostly used in automobiles, aerospace, and aircraft applications. Open-cell metallic foams of AMCs are used in electrodes, heat exchangers, filters, and shock absorbers while closed-cell AMC foams  are used in structural engineering applications such as automotive, aerospace, industrial equipment and building construction as they need lightweight structures having high strength, more stiffness, greater energy absorbing capacity, and  good damping of noise or vibration. The closed-cell aluminium foams are mostly used as a filler or core of a sandwich panel or thin structures on walls. Foams mostly increase the crashworthiness of AMC but it also increases its mechanical strength through strengthening its cell skeleton or by optimizing the pore structure. High strength foams used with AMCs broaden the applications of composites (Degischerab, 1997).

Aim of this research is to explore production process, properties, and applications of metal foams matrices of Aluminium Composite so that researcher can understand what reinforcements or metal foams can be used to make aluminium composite suitable for specific applications. To achieve this aim of the research project, following objectives would be fulfilled:

• To understand properties of metal foams matrices of Aluminium Composites
• To understand various methods of AMC metal foams production
• To explore various applications of Foamed AMCs
• To understand what types of metal foams add properties to make the metal suitable for specific applications

Applications of metal foams

This research would use an exploratory study in which the objectives of this research would be achieved so that conclusions can be made to solve certain problems identified by the researcher. The aim of this research is to understand how different methods of production and combination of foaming and composite formation can help modify properties of aluminium to make the composite suitable for specific applications. Thus, using the exploratory approach, the researcher would first explore the applications of aluminium composite and identify what properties of metal are required for these applications. Various production methods would then be explored to understand how they can produce foamed composite metals with different properties (Elliott & Timulak, 2005).

For the research, secondary qualitative methods would be used. The secondary sources like books, journals, and research reports would be used for collecting the qualitative data on properties, production and application of aluminium composite materials. The data obtained would be analysed using a descriptive approach that would explain the production processes and what differential properties are exhibited with these differences in the aluminium composites.

The data obtained would be used to create categories of composites based on their properties and applications. For this, the researcher would use own knowledge and critical thinking to identify the properties that are affected by different production methods and the need for those properties in specific applications. Based on this understanding, the researcher would come up with the recommendations on the use of appropriate aluminium composites for specific applications including healthcare, automotive, aerospace, and construction by matching the application needs with the composite material properties (Given, 2008).

The project is in its initial phase where the initial research is done on the properties, production processes, and applications of foamed aluminium composites. The researcher would further need to explore each type of composite or production process to understand what properties they add to the metal and at the same time also explore various applications these composites would be suitable for. Based on this analysis, recommendations would be made on the use of aluminium composite metals for specific business or industry applications.

The project would take 40 days to complete involving literature review study secondary data collection, analysis and reporting with relevant recommendations.

For this work, the researcher would not need any financial or human resources other than the researcher. For the research, the researcher would need to explore the journal articles and research reports from the library . For this, the researcher would use the college library and the online sources like Google Scholar and other online research databases to collect required data. As the data can be collected by a single individual if sufficient time is provided, the research would not need any other human resource for the current research except the research who would be visiting the library and online sources to get access to the reports and related data.

References

Banhart, J., 2000. Manufacturing Routes for Metallic Foams. JOM, 52(12), pp. 22-27.

Bodunrin, M. O., Alaneme, K. K. & Chown, L. H., 2015. Aluminium matrix hybrid composites: a review of reinforcement philosophies; mechanical, corrosion and tribological characteristics. Journal of Materials Research and Technology, 4(4), pp. 434-445.

Degischerab, H., 1997. Innovative light metals: metal matrix composites and foamed aluminium. Materials & Design, 4(6), pp. 221-226.

Drenchev, L., Sobczak, J. J., Sha, W. & Malinov, S., 2005. Mathematical model for simultaneous growth of gas and solid phases in gas-eutectic reaction. Journal of Materials Science, 40(9), pp. 2525-2530.

Duarte, I. & Ferreira, J. M. F., 2016. Composite and Nanocomposite Metal Foams. Materials (Basel)., 9(2), p. 79.

Elliott, R. & Timulak, L., 2005. Descriptive and interpretive approaches to qualitative research. s.l.:HRMC.

Given, L. M., 2008. Exploratory Data Analysis. s.l.:Sage Publications.

Güner, A., Ar?kan, M. M. & Nebioglu, M., 2015. New Approaches to Aluminum Integral Foam Production with Casting Methods. Metals, Volume 5, pp. 1553-1565.

Han, X.-h., Wang, Q., Park, Y.-G. & Jacobi, A., 2015. A Review of Metal Foam and Metal Matrix Composites for Heat Exchangers and Heat Sinks, s.l.: Zhejiang University.

Ramnath, B. V. et al., 2014. ALUMINIUM METAL MATRIX COMPOSITES – A REVIEW. Aluminium metal mater. Sci., Volume 38, pp. 55-60.

Srivastava, V. C. & Sahoo, K. L., 2007. Processing, stabilization and applications of metallic foams. Art of science. MATERIALS SCIENCE-POLAND , 25(3), pp. 733-739.