Composite Materials

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What is a Composite Material?

Composite materials are the combination of two or more materials that have their unique properties. Different types of composite materials are in use today, meeting the challenges and requirements of a technologically advanced world. For example applications of composite materials can be found ranging from space shuttles to huge construction sites. Another reason for the increase in the uses of composite materials, apart from the combined characteristics of materials are properties, such as being less expensive, light in weight and stronger when compared to common materials. Therefore, the applications of composite materials are found in diverse fields falling under the material application definition i.e. requiring materials to achieve the making of an object with specified properties.


Definition of Composite Materials

The composite material definition can be simply made from the introduction of composite materials. Thus, composite materials are the materials that are produced from the combination of two or more constituent materials. Although the constituent materials might have different and unique properties, they are merged together to form material unlike the individual materials and having the beneficial properties of all the constituents. The difference between composite materials and mixtures and solid solutions is that within the end product the individual components remain separate and distinct. Thus, composite materials meaning includes in the characteristics of composite materials, the unique properties of a material without actually fusing them into one another. 


Some of the typical examples of composite materials include:

  • Reinforced concrete,

  • Wooden composite materials

  • Ceramic material composites

  • Metal composite matrix

  • Reinforced plastics, etc. 

Other uses of composite materials based on the characteristics of composite material include in construction of buildings and bridges, making of the space shuttles, boats, bathtubs, storage tanks, racing cars, aircraft, etc. With the introduction of sensing, actuation, computation and higher-order communication in between the materials, it is used in creating components of robots and satellites as well. These are specialized applications of composite materials. With the development of material sciences, they are also used in the manufacturing of daily use gadgets such as mobile phones, drones, laptops, etc. 


History of Composite Materials

Since time immemorial, applications of composite materials have been numerous. One of the earliest composite materials were the bricks made from straw and mud for building construction. Also, one of the most widely used composite materials, concrete, has been in use since ancient times around 25 BCE. Woody composite materials made up of wood from true trees and plants such as palms and bamboo have been used since ancient times for making up scaffolding structures. Another such example is the use of plywood which has been in use since the ancient Mesopotamian civilization. All these examples of applications of composite materials provide a long connection with the needs of mankind of composite materials. 


The technology of composite materials saw new transformations like the invention of fibreglass. It is made up of glass fibres and polymeric materials, such as epoxy or polyester,  providing stiffness, strength, flexibility and durability to the finished product - a combination of both the constituent materials. In 1935, the first artificial reinforced plastic composite was produced using fibreglass and bakelite. Glass and plastic film over the thin electrical conductors made up of indium tin oxide make up the touch screens of the very commonly used smartphones and tablets. All this demonstrates a long and continuing journey of the use of different types of composites by mankind. 


Making up and Classification of Composite Materials

As understood from the composite material definition, a composite material is made up of two or more constituent materials. The classification of composite materials depends upon the two types of categories of constituent materials, which are the matrix and the reinforcement. An optimal combination of a variety of matrix and reinforcement materials are used to make composite materials that impart the required characteristics of composite materials. The matrix provides support to the reinforcement and the reinforcement, in turn, imparts its own physical and mechanical properties to the matrix. Thus, both the matrix and the reinforcement provide durability, sustainability and utility to the composite material meaning.  The classification of composite materials based on their matrix and reinforcement type is given below:

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For making the composite material, the reinforcement is placed on a mould surface or cavity. Depending on the matrix material, it is introduced to the reinforcement after or before being placed in the mould. Following this, the matrix undergoes a melding event setting up the required shape of the composite material. This melding can happen in several ways, such as solidification in the case of melting thermoplastic polymer matrix and chemical polymerization in the case of the thermoset polymer matrix. This process is the formation step of engineered composite materials. The moulding methods used depends on the requirements of the end-product. The nature of matrix and reinforcement materials influence this step which later defines the characteristics of composite materials.


Apart from the nature of the chosen material for the matrix and reinforcement, another factor that influences the moulding process is the gross quantities of material. For example, rapid and automated manufacturing technologies involving high investments, require large quantities of gross materials whereas for producing small quantities involving low investments and high labour the gross quantities required are less. Examples of a commercially used matrix material are resin which is a polymer matrix material that can be used for different moulding methodologies depending on the amount of monetary investment. The moulding processes are also influenced in small amounts by the types of composite materials that are needed to be produced. 


Conclusion

A brief understanding of the composite material and different types of composite materials which are classified based on unique properties and characteristics of composite materials required in the end-use is gained in this article. Also, the making of the composite material explains the nature of the composite material that is obtained from the constituent materials. The importance of the composite material and its utilization since ancient times underlines the importance of the composite materials as well. 

FAQs (Frequently Asked Questions)

1. What are Composite Materials and What is Their Classification?

Ans: Composite materials are those materials that are made from two or more constituent materials with each material having its unique properties and characteristics. The composite materials can be classified based on the two categories of materials that are used: the matrix (i.e. the binder) and the reinforcements. The matrix provides support to the reinforcement whereas the reinforcement enhances the physical and mechanical properties of the composite.

2. What are Examples of Composite Material?

Ans: The main examples of composite material include the following: reinforced concrete, reinforced plastics, woody composite materials, ceramic matrix composites, metal matrix composites, etc. A new variety of composite materials consisting of properties of sensing, high-level communication between the materials, etc are also present and are known as robotic composites.

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