Chapter 1 Next-generation waste residue composite materials

Abstract

Over the last two decades, global manufacturers have incessantly concentrated on developing advanced materials’ infused components. Automotive, aerospace, and structural industries widely use monolithic matrix materials like ferrous and nonferrous alloys. The ferrous materials have good properties but also have high density-to-weight ratio, which affects the products by increasing the components and vehicle body weight, thus reducing the fuel efficiency of the vehicle; hence, researchers have been working on replacing ferrous materials by introducing aluminum composites. Al-MMCs (aluminum metal matrix composites) are the fast replacing heavyweight ferrous materials. These materials satisfy the customer needs and technological demands such as devices and machinery that are energy-efficient, more durable, lightweight, and cost-efficient. This chapter describes a general introduction of composite materials, types of composites, Al-MMCs, and waste residues of Al-MMCs. The chapter examines the waste residue particles and their types, and replacement of synthetic reinforcement particles with these waste residues. Furthermore, the chemical composition, waste particle preparation, and mechanical and tribological properties are also explored. It has been found that the use of waste residue particles in a certain amount to Al material, the Al composite weight was reduced and gave better results than the synthetic added reinforced particles.

1.1 Introduction

Lightweight materials are integral parts in aircraft and automotive industries because their applications help reduce fuel consumption and emissions [1]. Earlier, cast iron alloys were extensively used for this purpose. However, the implementation of cast iron liners in engine blocks adds weight, increases production cost, and complicates recycling of blocks [2, 3]. Furthermore, according to Marsh [4], the automotive industry is facing continuous pressures to develop fuel-efficient, less-polluting vehicles. Therefore, industries started looking for alternative materials to replace the expensive alloys with improved specific strength and other desirable properties to make products that are lightweight and environmentally friendly. Among all cast alloys, aluminum alloys and steel-based alloys are cost-effective, reliable, and extensively used in engine blocks and piston and in assorted structural applications [5]. But these materials are expensive and are not lightweight. The ever-increasing requirement of new class of lightweight materials led to the usage of composites.

The past two decades have witnessed a continuous upward trend on the usage of composite materials primarily due to their highly specific and superior properties compared to monolithic materials. However, this makes the selection of secondary materials such as fibers, wickers, and reinforcement particles that are to be added to the matrix material that is extremely important. Composites are combinations of two or more materials that are amalgamated to form a new material with multiphase transitions. This creates the composites that can achieve more superior and desirable properties that the monolithic individual materials cannot attain. In composites, multiphases are not formed by naturally occurring reactions or phase transitions or other processes [6]. One such example is aluminum metal matrix composites (Al-MMCs). Al-MMCs are an incredibly attractive and efficient replacement for conventional alloys due to their tailored properties such as high specific strength, lightweight, stiffness, elastic modulus, and excellent resistance to wear and corrosion [7, 8]. The matrix material distributes the stress applied to it to the reinforcement constituents, protecting and shaping the matrix material. The reinforcement gives the composite material the desired mechanical strength in a preferred direction. Reinforcement comes in the form of wires, whiskers, or particulates, as well as continuous and discontinuous fibers that are distributed in different volume fraction percentages based on their properties. Except for wire reinforcements, others are made of ceramics such as oxides, carbides, and nitrides that have excellent properties such as specific strength and stiffness at both high and ambient temperatures, as described by Callister [7]. Therefore, these materials are widely adopted to satisfy the needs of various prominent industrial sectors such as construction, energy, electronics, biomedical, and aerospace [9]. Aluminum, magnesium, steel, and other matrices are commonly used as potential composite materials. A good MMC must have brittleness in the form of reinforcement and ductility in the form of a matrix. Titanium can also be used as a matrix in high-temperature applications. It is possible to tailor their properties to the needs of various industrial applications by combining appropriate matrix, reinforcement, and fabrication methods. These reinforcements are distinguished by their low coefficient of thermal expansion and high strength and modulus [10].

Metal matrix composites (MMCs) are classified into four main categories primarily based on the type of reinforcement being used. The MMC categories are shown in Figure 1.1:

• Dispersion hardened particle composites

• Layer composites (laminates)

• Fiber composites

• Infiltration composites [11]

Figure 1.1: Categories of reinforcement-based MMC composites.

The primary concentration of this chapter will be on dispersion hardened particle composites, also known as particle-reinforced MMCs.

1.2 Particle-reinforced composites

Particle reinforcement composites belong to the family of discontinuously reinforced composites. Particle reinforced composites are by far the most economic form of the composites. Their isotropic properties make them an ideal candidate for applications beyond aerospace and automotive industries. Usually, the reinforcement type for the development of the composites is based on the following criteria [12]:

• Compatibility with the matrix material

• Size and shape

• Density

• Melting temperature

• Thermal stability

• Coefficient of thermal expansion.

• Tensile strength (TS)

• Elastic modulus

• Cost

Ibrahim et al. considered various reinforcements used for the composite manufacturing examined clearly [13]. One might notice the primarily synthetic reinforcements and their properties in Figure 1.2. Aluminum-based MMCs were manufactured with many synthetic ceramic reinforcements due to their strength and desirable properties such as silicon nitride (Si3N4), alumina (Al2O3), aluminum titanate (Al2TiO5), zirconia (ZrSiO4), aluminum nitride (AlN), boron carbide (B4C), and silicon dioxide (SiO2) [14, 15, 16, 17, 18]. Nevertheless, high cost and inadequate availability of conventional ceramic reinforcements in developing countries prompted a compulsory paradigm shift in the choice of selection of reinforcement particles [19]. Although the reinforcement of these hard-ceramic particles enhances the performance of composites, their higher cost increases the overall cost. The processing cost of composites can be curtailed by utilization of waste residue particles across various industries like red mud (RM), fly ash (FA), cement, eggshell ash, rice husk ash (RHA), coconut shell ash, and biogas ash [20, 21].

Figure 1.2: Synthetic ceramic reinforcements and their properties.

Nowadays, researchers focus on replacing the synthetic reinforcement particles to waste residue reinforcement particles for adding to composites or hybrid composites. Waste residue composites are combinations of matrix materials with multiple solid reinforcements in which one of the phases has a 2D and a 3D structure. These composites are composed of a main...