Types of Materials

9 Key excerpts on "Types of Materials"

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  eBook - PDF

  The basics of engineering

  • Lokesh Pandey(Author)
  • 2023(Publication Date)
  • Arcler Press

    (Publisher)

  Engineering material is described as: “A topic that deals with the manufacture, qualities, and applications of materials utilized in applied engineering.” 5.1. INTRODUCTION Engineering materials range in weight from lightweight to heavyweight. Alloys for aircraft, Semiconductor chips for computers, Photovoltaic for energy storage, Semiconductor scanners, and so on. Material means engineering materials, limited to solid materials only. Science refers to the branch of applied science which deals with investigation of the relationship existing between the structure of materials and their properties. Materials differ from one another because of the difference in their properties for example, gold differs from iron because of its color, density, and corrosion resistance, among other things. Property differences occur owing to variations in material structure. All solid materials are made up of a huge number of molecules that are linked together to create the bulk substance. Each molecule is made up of microscopic particles known as atoms. The qualities and structure of a material are determined by the individual properties of atoms and their order in the molecule. A design engineer’s understanding of materials and their characteristics is critical. The machine elements should be built of a material that is suitable for the operating circumstances. A design engineer must also be knowledgeable about the impact of manufacturing techniques and heat treatment on the characteristics of materials (Figure 5.1). Engineering Materials and Their Applications 129 Figure 5.1. Image showing engineering material. Source: Image by archdaily.com. We will explore the most often used engineering materials and their qualities in this section. Metallurgy is the science and technique of economically extracting metals from their ores, purifying them, and preparing them for use. It investigates the microstructure of a metal, the structural details that may be observed under a microscope.

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  An Introduction to Mechanical Engineering: Part 1

  • Michael Clifford, Kathy Simmons, Philip Shipway(Authors)
  • 2009(Publication Date)
  • CRC Press

    (Publisher)

  Methods for measuring these properties are given, along with the origin of these properties (understanding this can help us to create new and improved materials). Finally, worked examples for designing with materials and how to select the best engineering material for a particular application are presented. Classification of materials Broadly speaking, we can place the thousands of materials available into several categories. These categories, or classes, contain materials with similar types of bond (see Underpinning Principles 1) which hold together the basic building blocks (atoms or molecules) of the material. Since the nature of the bonding defines the physical and mechanical properties, materials in the same class share similar properties and are suitable for similar applications. It should be noted that while some of the characteristic properties of materials in a particular class might be broadly the same (i.e. they might all be brittle or they might all be good electrical conductors), there can also be a wide variation in other basic properties (for example, mercury and tungsten are both metals, but have very different melting points). Materials are commonly classified into the following four groups: (i) metals, (ii) ceramics and glasses, (iii) polymers and elastomers and (iv) composite materials. An Introduction to Mechanical Engineering: Part 1 60 This unit outlines: ✔ the main classes of materials available to the design engineer, the attributes of these materials and how these attributes may be measured; ✔ the use of such attributes in the design process; ✔ the way that the various classes of material may be formed into components; ✔ the ways that processing will change the attributes of the materials.

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  Introduction to Engineering Materials

  • George Murray, Charles V. White, Wolfgang Weise(Authors)
  • 2007(Publication Date)
  • CRC Press

    (Publisher)

  1 1 Classification of Materials 1.1 INTRODUCTION Advancements in technology in most industries have been associated with the development of new materials and processes as well as advances in the state of the art of existing materials and combinations thereof. It is estimated that currently about 85,000 materials are available for industrial applications. In considering which materials to use for a particular structure or device, the selection process is further complicated by the wide variation in properties of materials with the manner in which the material is processed, for example, the heat treatment time, temperature, and cooling rate used for certain alloys. Some type of materials classification is an essential part of the selection process and an important element of engineering education. In the following sections, materials will be classified in the broad categories of metals, polymers, ceramics, composites, and semiconductors. In subsequent chapters, these materials and their associated processing methods will be pre-sented in more detail. In the design and material selection procedures, items such as the recycling potential of the material and environmental problems must be considered. 1.1.1 R ECYCLING Recycling is generally considered to be a part of solid waste management strat-egies. Any strategy devised must be incorporated in the material selection and design steps. Polymers are of much concern in recycling because many are nonbiodegrad-able and consist of about 20% of municipal solid waste. The thermoplastic polymers, which are easily formed and are abundant in packaging materials, have been given the most attention in terms of recycling technology. Representing about 90% of all plastics sold, they consist primarily of polyethylene, polyeth-ylene terephthalate (PET), polystyrene, polypropylene, and polyvinyl chloride (PVC).

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  eBook - ePub

  Introduction to Mechanical Engineering

  Part 1

  • Michael Clifford(Author)
  • 2022(Publication Date)
  • CRC Press

    (Publisher)

  Before we can select a material, or design with it, we need to understand the basic requirements (or properties it must have) for it to fulfil its function (for example, it might need to have a high melting point or absorb a large amount of energy on impact). With this understanding and a knowledge of how these properties vary for different types (or classes) of material, we can make a broad choice of material that would be suitable (a metal would be most suitable in this instance). With data for the properties of different materials and the equations that govern the behaviour under the appropriate conditions, we can select a specific material and define the geometry required.

  This section gives a broad introduction to materials and their properties. First, the structures of different broad classes of material (metals, ceramics and polymers) are described and these are then related to their characteristic properties. In Section 2.3 , a number of important material properties are then defined and their relevance in engineering contexts is outlined. Methods for measuring these properties are given, along with the origin of these properties (understanding this can help us to create new and improved materials). And then, in Section 2.4 , worked examples for designing with materials and how to select the best engineering material for a particular application are presented.

  Classification of Materials

  Broadly speaking, we can place the thousands of materials available into several categories. These categories, or classes, contain materials with similar types of bond (see Underpinning Principles 1) which hold together the basic building blocks (atoms or molecules) of the material. Since the nature of the bonding defines the physical and mechanical properties, there is similarity in some of the properties for materials in the same class. It should be noted that while some of the characteristic properties of materials in a particular class might be broadly the same (i.e. they might all be brittle or they might all be good electrical conductors), there can also be a wide variation in other basic properties (for example, mercury and tungsten are both metals, but have very different melting points). Materials are commonly classified into the following four groups or classes: (i) metals, (ii) ceramics and glasses, (iii) polymers and elastomers and (iv) composite materials.

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  eBook - ePub

  Manufacturing Engineering Processes, Second Edition

  • Leo Alting(Author)
  • 2020(Publication Date)
  • CRC Press

    (Publisher)

  In forming from the liquid material state, the final material properties depend mainly on the composition (including solidification temperature range), the thermal and mechanical properties of the molding or die material, and the solidification conditions (direction, rate, etc.). In forming from the solid material state by plastic deformation, the amount of deformation, the temperature, and the rate of deformation primarily determine the final properties. Cold deformation increases the strength and decreases the ductility of the material. Hot deformation gives poor surface quality and reasonably good mechanical properties. Solid-state forming by machining (mass-reducing processes) primarily influences the surface properties (roughness, hardness, internal stresses, etc.). The examples mentioned only serve to illustrate the complexity of the evaluation of the final material properties of a component. These problems are discussed in more detail in some of the later chapters.

  3.4 CLASSIFICATION OF MATERIALS

  As mentioned previously, it is very difficult to provide broad information regarding all the important engineering materials in this context. Consequently, only a general survey will be given to allow a rough evaluation of the suitability of the different material groups for various processes. From this survey and the process descriptions in the later chapters, a reasonable background for the evaluation of the final properties of the materials will be available.

  Engineering materials can be divided into groups showing important relationships. In this context the traditional classification shown in Fig. 3.1 will be followed.

  The main groups are metallic materials, nonmetallic materials, and composite materials. Composite materials are built up from two or more materials, so that new and special properties are obtained. Metallic materials are subdivided into ferrous and nonferrous metals. The nonmetallic materials are subdivided into polymers, ceramics, and glasses, but the group covers many other materials (wood, concrete, bricks, etc.) that are not important for the present discussion.

  FIGURE 3.1 Classification of some of the engineering materials.

  3.5 METALLIC MATERIALS

  3.5.1 Bonding and Structure

  Metals are characterized by the metallic bonding , where the metal ions are held together by an “electron cloud.” This type of bonding has a high mobility of the free (valence) electrons and accounts in general for the high strength level, the ductility (ability to be deformed without fracture), and the relatively high melting temperature of metals. These general tendencies can be influenced by many factors; consequently, exceptions are common.

  Metals have a crystalline structure with predominantly body-centered cubic, face-centered cubic, or close-packed hexagonal lattice structures. Crystalline materials normally consist of thousands of small individual crystals or grains, depending on the production method. During solidification, many individual lattices begin to form at various points within the melt. As solidification proceeds these crystals or grains, which have random orientation, grow, meet, and form the grain boundaries (Fig. 3.2

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  Engineering Problem Solving

  A Classical Perspective

  • Milton C. Shaw(Author)
  • 2001(Publication Date)
  • William Andrew

    (Publisher)

  Engineering Materials 197 197 1.0 INTRODUCTION There is a wide variety of materials an engineer may specify when designing a product and these will be discussed briefly in this chapter. They include the following: • Metals • Polymers • Glasses and Ceramics • Rock and Concrete • Composites 2.0 METALS Metals are particularly important since they are relatively strong, good conductors of heat and electricity, and may be made relatively ductile (deformable without fracture) by controlling their structure. Ductility makes it possible for them to be given a desired shape by plastic forming as well as by casting and stock removal by cutting and grinding. 9 Engineering Materials 198 Engineering Problem Solving: A Classical Perspective 2.1 Carbon Steels Carbon steel is an alloy of iron and carbon. Iron at room temperature has a very low carbon solubility (0.05 wt %). Therefore, a steel containing 0.40 wt % carbon will contain precipitated carbon in the form of a hard compound (Fe 3 C) called cementite. Iron above a critical temperature (about 1,400°F) changes its atomic structure from bcc (called ferrite or α iron) to fcc (called austenite or γ iron) and the carbon solubility is greatly increased. The atomic arrangements for α iron (bcc room temperature form) and γ iron (fcc high temperature form) have been shown in Fig. 8.4. By heating and cooling steel at different rates, carbon can be put into solution and precipi-tated. The size and distribution of the carbides depends on the rate of cooling. The carbides may be in the form of: 1. Large spheres (a structure called spheroidite) 2. Alternate plates of Fe 3 C and α iron (pearlite) 3. Small Fe 3 C particles (tempered martensite) The spacing of carbides in a steel gives rise to a mean ferrite path (mean distance between adjacent carbides), which in turn gives rise to a variety of properties.

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  Advances in Technology

  Education and Development

  • Wim Kouwenhoven(Author)
  • 2009(Publication Date)
  • IntechOpen

    (Publisher)

  The essential motivation for this helpful concept is to give the engineering students tools that they can immediately start to use in their role as engineers or designers. This “thinking behind the approach” makes maximum use of computer-assisted methods that further stimulate engagement of student and support project work that can be set by the teacher or self-generated by the student. Research, Development and Technology Transfer (R & D & TT) in the Field of Engineering Materials and Related Technologies 327 Fig. 1. The virtual world of engineering materials (Ashby & Cebon, 2002). The “world” of engineering materials (Fig. 1) shows the “families“, like: polymers, metals, ceramics, glasses, natural materials, and composites and hybrides that can be synthesised by combining these. Each family embraces classes, sub-classes and members. Every member is characterised by a set of attributes - its “property profile”. This structure has the merit that it is easily understood and allows a helpful concept: that of the “material property chart”, of which Figure 2 is a simple example. It is a map of one slice through material-property space. It plots stiffness, measured by Young’s modulus, against weight, measured by density. It is one of a set, mapping the territory occupied by each family and the spaces in between. The bold balloons enclose the members of the families: metals, polymers, ceramics, foams and so on. Within each of them are the classes; if the resolution were sufficient, the members would come into focus. Student interest is stimulated by encouragement to use these to explore the materials world. For engineering students it is very stimulating to use modern advisable software – so called Cambridge Engineering Selector (CES) to create charts with any desired combination of properties, giving the ability to zoom in on any selected part to increase resolution, and to access records for the attributes of individual materials.

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  Fundamentals of Materials Science and Engineering

  An Integrated Approach

  • William D. Callister, Jr., David G. Rethwisch(Authors)
  • 2022(Publication Date)
  • Wiley

    (Publisher)

  Approximately 100×. (Courtesy Sandia National Laboratories, SUMMiT* Technologies, www.mems.sandia.gov.) 668  Chapter 14 Types and Applications of Materials are undoubtedly many unforeseen uses of this MEMS technology that will have a pro- found impact on society; these will probably overshadow the effects that microelectronic integrated circuits have had during the last four decades. Types of Polymers There are many different polymeric materials that are familiar and find a wide vari- ety of applications; in fact, one way of classifying them is according to their end use. Within this scheme the various polymer types include plastics, elastomers (or rubbers), fibers, coatings, adhesives, foams, and films. Depending on its properties, a particular polymer may be used in two or more of these application categories. For example, a plastic, if crosslinked and used above its glass transition temperature, may make a satisfactory elastomer, or a fiber material may be used as a plastic if it is not drawn into filaments. This portion of the chapter includes a brief discussion of each of these types of polymer. 14.13 | | PLASTICS Possibly the largest number of different polymeric materials come under the plastic clas- sification. Plastics are materials that have some structural rigidity under load and are used in general-purpose applications. Polyethylene, polypropylene, poly(vinyl chloride), polystyrene, and the fluorocarbons, epoxies, phenolics, and polyesters may all be classified as plastics. They have a wide variety of combinations of properties. Some plastics are very rigid and brittle (Figure 8.22, curve A). Others are flexible, exhibiting both elastic and plastic deformations when stressed and sometimes experiencing considerable deformation before fracture (Figure 8.22, curve B). Polymers falling within this classification may have any degree of crystallinity, and all molecular structures and configurations (linear, branched, isotactic, etc.) are possible.

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  Engineering Textiles

  Integrating the Design and Manufacture of Textile Products

  • Yehia Elmogahzy(Author)
  • 2019(Publication Date)
  • Woodhead Publishing

    (Publisher)

  7

  Material selection

  Abstract

  Material selection represents the most critical aspect of design engineering. Understanding material structure, properties, and processing represents a common knowledge base between scientists, engineers, and technologists. Many design problems are solved either by selecting raw materials of better attributes or by changing the type of material used. The fact that material can be stiff, strong, ductile, brittle, tough, or hard provides numerous design options that are suitable for a wide range of end products. Since raw material makes up the building blocks of all manufacturing processes, the choice of one raw material versus another could mean substantial cost reduction. This point is very common in textile technology in which manufacturing cost is often minimized by the choice of an appropriate fiber type or blending fibers of different prices at predetermined ratios and under quality constraints. In this chapter, basic steps of material selection in design applications are discussed. The key tasks of evaluating material candidates for a certain product are reviewed. These include (a) knowledge of the common material categories (i.e., screening category), (b) understanding basic material properties (i.e., screening property), (c) determining the optimum cost of material with respect to its performance and its contribution to the value of the end product, (d) understanding the effects of technology on material selection, and (e) understanding the differences between design-direct and value-impact performance characteristics. Many examples of fibrous materials are presented in the context of these tasks.

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