Engineering Materials & Minerals

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1 Course Book Engineering Materials & Minerals Lecturer: Dr.Payman Suhbat Ahmed Coordinator: Nawzat Rashad Ismail 2 nd Stage Petroleum Engineering Department Engineering Faculty Koya University

2 Course Overview In this course the student will learn in detail the very important topics in Engineering Materials from the basics concepts to the traditional and advanced application passing by their processing, characterization and testing to make students able to select the appropriate material for the right application. application. Course Objective To make students able to select the appropriate material for the right Course Reading References - Materials Science and Engineering An Introduction, William D. Callister, Jr.

3 Weeks Lectures Schedule Contents 1 Introduction 2 Atomic Structure and Interatomic Bonding 3&4 Structures of Metals and Ceramics 5 Polymer Structures 6 Composites 7&8 Thermal Properties 9&10 Magnetic Properties 11&12 Optical Properties 13&14 Electrical Properties 15 Imperfections in Solids Mechanical Properties 19&20 Deformation and Strengthening Mechanisms 21&22 Failure 23&24 Phase Diagrams 25&26 Synthesis, Fabrication, and Processing of Materials 27 Applications of Materials 28 Corrosion and Degradation of Materials

4 Exams: There will be two exams (each at the end of first and second semester) and one final. Quizzes: There will be sudden quizzes at each semester. General Instructions and Commandments: 1- Not eligible for the student to inter the lecture after the lecturer. 2- The student is responsible for any oral or written notes that mention in the lecture hall. 3- It is not allowed to the student to borrow a pen or calculator or anything during the exam. 4- It is not allowed to re-exam, just by an official excuse.

5 Topic No.1 Introduction Sometimes it is useful to subdivide the discipline of materials science and engineering into materials science and materials engineering subdisciplines. Strictly speaking, materials science involves investigating the relationships that exist between the structures and properties of materials. In contrast, materials engineering is, on the basis of these structure property correlations, designing or engineering the structure of a material to produce a predetermined set of properties. From a functional perspective, the role of a materials scientist is to develop or synthesize new materials, whereas a materials engineer is called upon to create new products or systems using existing materials, and/or to develop techniques for processing materials. Topic No.2 Atomic Structure and Interatomic Bonding An important reason to have an understanding of interatomic bonding in solids is that, in some instances, the type of bond allows us to explain a material s properties. For example, consider carbon, which may exist as both graphite and diamond. Whereas graphite is relatively soft and has a greasy feel to it, diamond is the hardest known material. This dramatic disparity in properties is directly attributable to a type of interatomic bonding found in graphite that does not exist in diamond.

6 Topic No.3&4 Structure of Metals and Ceramics The properties of some materials are directly related to their crystal structures. For example, pure and undeformed magnesium and beryllium, having one crystal structure, are much more brittle (i.e., fracture at lower degrees of deformation) than are pure and undeformed metals such as gold and silver that have yet another crystal structure. Furthermore, significant property differences exist between crystalline and noncrystalline materials having the same composition. For example, noncrystalline ceramics and polymers normally are optically transparent; the same materials in crystalline (or semicrystalline) form tend to be opaque or, at best, translucent. Metals Materials in this group are composed of one or more metallic elements (such as iron, aluminum, copper, titanium, gold, and nickel), and often also nonmetallic elements (for example, carbon, nitrogen, and oxygen) in relatively small amounts.3 Atoms in metals and their alloys are arranged in a very orderly manner and in comparison to the ceramics and polymers, are relatively dense. With regard to mechanical characteristics, these materials are relatively stiff and strong, yet are ductile (i.e., capable of large amounts of deformation without fracture), and are resistant to fracture, which accounts for their widespread use in structural applications. Metallic materials have large numbers of nonlocalized electrons; that is, these electrons are not bound to particular atoms. Many properties of metals are directly attributable to these electrons. For example, metals are extremely good conductors of electricity and heat, and are not transparent to visible light; a polished metal surface has a lustrous appearance. In addition, some of the metals (viz., Fe, Co, and Ni) have desirable magnetic properties. Figure below is a photograph that shows several common and familiar objects that are made of metallic materials.

7 Familiar objects that are made of metals and metal alloys: (from left to right) silverware (fork and knife), scissors, coins, a gear, a wedding ring, and a nut and bolt. Ceramics Ceramics are compounds between metallic and nonmetallic elements; they are most frequently oxides, nitrides, and carbides. For example, some of the common ceramic materials include aluminum oxide (or alumina,al2o3), silicon dioxide (or silica, SiO2), silicon carbide (SiC), silicon nitride (Si3N4), and, in addition, what some refer to as the traditional ceramics those composed of clay minerals (i.e., porcelain), as well as cement, and glass. With regard to mechanical behavior, ceramic materials are relatively stiff and strong stiffnesses and strengths are comparable to those of the metals. In addition, ceramics are typically very hard. On the other hand, they are extremely brittle (lack ductility), and are highly susceptible to fracture. These materials are typically insulative to the passage of heat and electricity (i.e., have low electrical conductivities), and are more resistant to high temperatures and harsh environments than metals and polymers.with regard to optical characteristics, ceramics may be transparent, translucent, or opaque, and some of the oxide ceramics (e.g., Fe3O4) exhibit magnetic behavior. Several common ceramic objects are shown in the photograph of Figure below.

8 Common objects that are made of ceramic materials: scissors, a china tea cup, a building brick, a floor tile, and a glass vase. Topic No.5 Structure of Polymer Polymers include the familiar plastic and rubber materials. Many of them are organic compounds that are chemically based on carbon, hydrogen, and other nonmetallic elements (viz.o,n, and Si). Furthermore, they have very large molecular structures, often chain-like in nature that have a backbone of carbon atoms. Some of the common and familiar polymers are polyethylene (PE), nylon, poly(vinyl chloride) (PVC), polycarbonate (PC), polystyrene (PS), and silicone rubber. These materials typically have low densities, whereas their mechanical characteristics are generally dissimilar to the metallic and ceramic materials they are not as stiff nor as strong as these other material types. However, on the basis of their low densities, many times their stiffnesses and strengths on a per mass basis are comparable to the metals and ceramics. In addition, many of the polymers are extremely ductile and pliable (i.e., plastic), which means they are easily formed into complex shapes. In general, they are relatively inert chemically and unreactive in a large number of environments. One major drawback to the polymers is their tendency to soften and/or decompose at modest temperatures, which, in some instances, limits their use. Furthermore, they have low electrical conductivities and are nonmagnetic.

9 The photograph in Figure below shows several articles made of polymers that are familiar to the reader. Topic No.6 Composites With a knowledge of the various types of composites, as well as an understanding of the dependence of their behaviors on the characteristics, relative amounts, geometry/distribution, and properties of the constituent phases, it is possible to design materials with property combinations that are better than those found in the metal alloys, ceramics, and polymeric materials. For example, in Design Example, we discuss how a tubular shaft is designed that meets specified stiffness requirements.

10 Topic No.7&8 Thermal Properties Materials selection decisions for components that are exposed to elevated/subambient temperatures, temperature changes, and/or thermal gradients require the design engineer to have an understanding of the thermal responses of materials, as well as access to the thermal properties of a wide variety of materials. For example, in the discussion on materials that are used for the lead frame component of an integrated circuit package, we note restrictions that are imposed on the thermal characteristics of the adhesive material that attaches the integrated circuit chip to the leadframe plate. This adhesive must be thermally conductive so as to facilitate the dissipation of heat generated by the chip. In addition, its thermal expansion/contraction on heating/cooling must match that of the chip such that the integrity of the adhesive-chip bond is maintained during thermal cycling. Topic No.9&10 Magnetic Properties An understanding of the mechanism that explains the permanent magnetic behavior of some materials may allow us to alter and in some cases tailor the magnetic properties. For example, in Design Example the behavior of a ceramic magnetic material may be enhanced by changing its composition.

11 Topic No.11&12 Optical Properties When materials are exposed to electromagnetic radiation, it is sometimes important to be able to predict and alter their responses. This is possible when we are familiar with their optical properties and understand the mechanisms responsible for their optical behaviors. For example, on optical fiber materials, we note that the performance of optical fibers is increased by introducing a gradual variation of the index of refraction (i.e., a graded index) at the outer surface of the fiber. This is accomplished by the addition of specific impurities in controlled concentrations. Topic No.13&14 Electrical Properties Consideration of the electrical properties of materials is often important when materials selection and processing decisions are being made during the design of a component or structure. For example, we discuss that are used in the several components of one type of integrated circuit package. The electrical behaviors of the various materials are diverse. Some need to be highly electrically conductive (e.g., connecting wires), whereas electrical insulativity is required of others (e.g., the protective package encapsulation).

12 Topic No.15 Imperfections in Solids The properties of some materials are profoundly influenced by the presence of imperfections. Consequently, it is important to have a knowledge about the types of imperfections that exist and the roles they play in affecting the behavior of materials. For example, the mechanical properties of pure metals experience significant alterations when alloyed (i.e., when impurity atoms are added) for example, brass (70% copper 30% zinc) is much harder and stronger than pure copper. Also, integrated circuit microelectronic devices found in our computers, calculators, and home appliances function because of highly controlled concentrations of specific impurities that are incorporated into small, localized regions of semiconducting materials. Topic No Mechanical Properties It is incumbent on engineers to understand how the various mechanical properties are measured and what these properties represent; they may be called upon to design structures/components using predetermined materials such that unacceptable levels of deformation and/or failure will not occur.

13 Topic No.19&20 Deformation and Strengthening Mechanisms With a knowledge of the nature of dislocations and the role they play in the plastic deformation process, we are able to understand the underlying mechanisms of the techniques that are used to strengthen and harden metals and their alloys. Thus, it becomes possible to design and tailor the mechanical properties of materials for example, the strength or toughness of a metal matrix composite. Topic No. 21&22 Failure The design of a component or structure often calls upon the engineer to minimize the possibility of failure. Thus, it is important to understand the mechanics of the various failure modes i.e., fracture, fatigue, and creep and, in addition, be familiar with appropriate design principles that may be employed to prevent in-service failures.

14 Topic No.23&24 Phase Diagram One reason that a knowledge and understanding of phase diagrams is important to the engineer relates to the design and control of heat-treating procedures; some properties of materials are functions of their microstructures, and, consequently, of their thermal histories. Even though most phase diagrams represent stable (or equilibrium) states and microstructures, they are nevertheless useful in understanding the development and preservation of nonequilibrium structures and their attendant properties; it is often the case that these properties are more desirable than those associated with the equilibrium state. This is aptly illustrated by the phenomenon of precipitation hardening. Topic No.25&26 Synthesis, Fabrication, and Processing of Materials It is important for the engineer to realize how the applications and processing of ceramic materials are influenced by their mechanical and thermal properties, such as hardness, brittleness, and high melting temperatures. For example, ceramic pieces normally cannot be fabricated using conventional metal forming techniques. they are often formed using powder compaction methods, and subsequently fired (i.e., heat treated).

15 Topic No.27 Applications of Materials Engineers are often involved in materials selection decisions, which necessitates that they have some familiarity with the general characteristics of a wide variety of metals and their alloys (as well as other material types). In addition, access to databases containing property values for a large number of materials may be required. Topic No. 28 Corrosion and Degradation of Materials With a knowledge of the types of and an understanding of the mechanisms and causes of corrosion and degradation, it is possible to take measures to prevent them from occurring. For example, we may change the nature of the environment, select a material that is relatively nonreactive, and/or protect the material from appreciable deterioration.