Nigeria's free digital learning hub. Videos, lecture notes, practice questions and leaderboards aligned with CCMAS, NBTE, NCCE, WAEC, NECO, IJMB and JAMB curricula.
Loading
Nigeria's free digital learning hub. Videos, lecture notes, practice questions and leaderboards aligned with CCMAS, NBTE, NCCE, WAEC, NECO, IJMB and JAMB curricula.
This is the complete lecture note for MME401 Synthesis, Processing, and Manufacturing of Materials. You can read it online below, open it in the full viewer, or download the PDF for offline study. It pairs with the course's video lectures, so you can read and watch together.
Course code: MME 401 Course title: Synthesis, Processing, and Manufacturing of Materials Course credit load: 2 Units Series 1: Synthesis, Processing and Manufacturing of Materials: Fundamental Concepts ● Part 1.1: Engineering Materials and Their Classification o Sub Part 1.1.1: Classes of Engineering Materials o Sub Part 1.1.2: Bonding and Structure as the Basis of Properties o Sub Part 1.1.3: Principal Alloy, Ceramic and Polymer Systems ● Part 1.2: Synthesis and Processing Distinguished o Sub Part 1.2.1: The Meaning of Synthesis o Sub Part 1.2.2: The Meaning of Processing o Sub Part 1.2.3: Distinguishing Synthesis, Processing and Manufacturing ● Part 1.3: Overview of Processing and Manufacturing of Engineering Materials o Sub Part 1.3.1: Processing of Metals o Sub Part 1.3.2: Processing of Ceramics o Sub Part 1.3.3: Processing of Polymers ● Part 1.4: Properties, Performance and Selection of Materials o Sub Part 1.4.1: Material Properties and Their Categories o Sub Part 1.4.2: How Changes in Properties Enhance Performance o Sub Part 1.4.3: Structure, Processing, Properties and Performance Introduction Every object you use in a day, from the casing of a mobile phone to the cable of a bridge, had first to be made of something and then made into something. Those two ideas, making a material
and making it useful, sit at the heart of this course. Before studying particular alloys, ceramics and polymers, it helps to be clear about what is being made, how the steps differ and why the properties that result matter so much. The aim of this Series is to equip you to classify engineering materials, differentiate between synthesis and processing, outline the common processing methods for metals, ceramics and polymers, and explain how changes in properties enhance performance. We shall commence with engineering materials and their classification, which introduces the three main material classes. Next, we will explore the meaning of synthesis and processing and how they differ. Afterwards, we will turn to an overview of the processing and manufacturing of metals, ceramics and polymers. We will conclude with properties, performance and the link between structure and processing. Series Learning Outcomes Upon completing this Series, you should be able to: ● SLO 1.1: classify engineering materials into metals, ceramics and polymers, ● SLO 1.2: explain how bonding and structure account for the general properties of metals, ceramics and polymers, ● SLO 1.3: define synthesis and processing of materials, ● SLO 1.4: differentiate between synthesis and processing, ● SLO 1.5: outline the common processing and manufacturing methods for metals, ceramics and polymers, ● SLO 1.6: compare the processing routes of metals, ceramics and polymers, ● SLO 1.7: classify the properties of engineering materials as mechanical, physical or chemical, ● SLO 1.8: explain how changes in material properties enhance the performance of a material. 1.1 Engineering Materials and Their Classification 1.1.1 Classes of Engineering Materials Engineering materials are the materials selected and used to make components, structures and devices, and they are commonly grouped into three main classes: metals, ceramics and polymers. Metals are elements or alloys held together by metallic bonding, such as iron, aluminium, copper and their alloys. Ceramics are inorganic, non-metallic compounds of metallic and non-metallic
elements, such as alumina and silica. Polymers are materials made of long chain molecules built from repeating units, chiefly of carbon and hydrogen, such as polyethylene. Each class has a characteristic profile of properties. Metals are strong, ductile and good conductors of heat and electricity. Ceramics are hard, brittle, resistant to heat and corrosion, and poor conductors. Polymers are light, easily shaped and usually electrical insulators, but they are generally weaker and soften at relatively low temperatures. These general profiles guide the first choice of material for a job, although exceptions exist within every class. Worked example: A cooking pot needs good heat conduction and toughness, so a metal is chosen, a furnace lining must survive very high temperature, so a ceramic is chosen, and a water bottle needs low weight and easy moulding, so a polymer is chosen. Application: Knowing the general profile of each class allows a first, quick match between a material and a service requirement. Fill in the blank: Materials made of long chain molecules built from repeating units are called __________. 1.1.2 Bonding and Structure as the Basis of Properties The properties of a material arise from the way its atoms are bonded and arranged. In metals, metallic bonding shares delocalised electrons among positive ions, giving good conductivity and the ability to deform without breaking. In ceramics, ionic and covalent bonding are strong and directional, which gives high hardness and melting point but little ability to deform, so ceramics are brittle. In polymers, strong covalent bonds hold the atoms together along each chain, but only weak secondary bonds hold the chains to one another. Structure operates at larger scales too. Metals and most ceramics are crystalline, with atoms arranged in a regular pattern that repeats in three dimensions, whereas glasses and many polymers are wholly or partly non-crystalline. Grain size, phases and defects further modify properties. Because processing can change this structure without changing the composition, the same material can show very different properties after different treatment, which is why processing matters so much to engineers. Worked example: Ceramics are brittle because their directional ionic and covalent bonds resist the sliding of atomic planes, whereas metals deform because the non-directional metallic bond lets planes slide. Application: Linking a property to its bonding and structure allows an engineer to predict how a material will behave before testing it. Fill in the blank: In polymers, the chains are held to one another by weak __________ bonds. 1.1.3 Principal Alloy, Ceramic and Polymer Systems A material system is a family of materials that share the same principal constituents and can be described together, such as the iron-carbon alloys. The principal alloy systems used in engineering include the ferrous alloys, steels and cast irons, and the non-ferrous alloys based on aluminium, copper, nickel, titanium and magnesium. Each system is important because its
properties can be varied widely through composition and processing, which is why one family can serve many different applications. The principal ceramic systems include the oxides, such as alumina and silica, the carbides and nitrides, such as silicon carbide, and the glasses and clay-based products. The principal polymer systems include the thermoplastics, such as polyethylene, polypropylene and polyvinyl chloride, the thermosets, such as epoxies and phenolics, and the elastomers, such as natural rubber. Each system is studied separately later in the course, with its own methods of synthesis and processing. Worked example: Steels form a principal alloy system based on iron and carbon, whereas polyethylene, polypropylene and polyvinyl chloride belong to the thermoplastic group of the polymer systems. Application: Grouping materials into systems lets engineers study and compare them in an organised way rather than one material at a time. Fill in the blank: A family of materials that share the same principal constituents is called a material __________. Figure 1.1: Classification of engineering materials and their principal systems. Pilot questions 1.1 1. Name the three main classes of engineering materials. (Linked to SLO 1.1) 2. Which class of material is generally hard, brittle and resistant to high temperature? (Linked to SLO 1.1) 3. Which class of material is made of long chain molecules? (Linked to SLO 1.1)
4. Why are ceramics brittle? (Linked to SLO 1.2) 5. What holds the chains of a polymer to one another? (Linked to SLO 1.2) 1.2 Synthesis and Processing Distinguished 1.2.1 The Meaning of Synthesis Synthesis is the production of a material from its raw materials or from simpler chemical constituents, so that a material with a specified composition and basic structure is created. The starting point may be ores, minerals, petroleum products or purified powders, and the result is the material itself in a basic form, such as an alloy ingot, a ceramic powder or a polymer resin. Synthesis therefore determines what a material is chemically. Each material class has its own synthesis routes. Alloys are synthesised by melting and mixing the constituent metals in controlled proportions, and ceramics by the chemical reaction or heating of mineral powders. Polymers are synthesised by joining small molecules, called monomers, into long chains through polymerisation. In all cases, the control of composition and purity at this stage decides many of the properties of the final material, and impurities left behind can be difficult to remove later. Worked example: Melting copper and zinc together in a ratio of 70 to 30 synthesises brass, and joining ethylene molecules into long chains synthesises polyethylene. Application: Controlling composition and purity during synthesis fixes the chemical identity of a material before any shaping begins. Fill in the blank: The production of a material from its raw materials or simpler chemical constituents is called __________. 1.2.2 The Meaning of Processing Processing is the set of operations that convert a synthesised material into a required shape, structure and set of properties, usually without changing its overall composition. It includes shaping operations, such as casting and forming, and structure-controlling
This is the opening of the note. Read the full note or download the PDF to continue.
