CE SummerDr SaMeH1 Properties of Materials & Strength 2 (CE 212) [2] Associate Professor of Environmental Eng. Civil and Environmental Engineering Department Faculty of Engineering Majma’ah University faculty.mu.edu.sa/smohamed/SaMeH Summer Semester Sameh Saadeldin Ahmed

Material Science and Engineering CE SummerDr SaMeH2 Chapter (1b) Introduction

CE SummerDr SaMeH3 1.Learning Objectives √ 2.Historical Prospective √ 3.Material Science and Engineering √ 4.Why do we study material sciences? √ 5.Material Composition √ 6.Classifications of Materials 7. Material Selection Outlines

CE SummerDr SaMeH4 1.6 Classifications of Materials  Solid minerals are can be classify into 3 groups: Metals, Ceramics and Polymers The above classification is based on the chemical makeup and atomic structure and most materials fall into one distinct grouping or another, although there are intermediates.  In addition, there are three other groups of important engineering materials: Composites, Semiconductors and Biomaterials Composites : consist of combinations of two or more different materials. Semiconductors : are utilized because of their unusual electrical characteristics. Biomaterials: are implanted into the human body.

CE SummerDr SaMeH5 Solid Materials Metals Ceramics Polymers Engg. Materials Composites Semiconductors Biomaterials

CE SummerDr SaMeH Metals  A metal is a material (an element, compound, or alloy) that is typically hard, opaque, shiny, and has good electrical and thermal conductivity. About 91 of the 118 elements in the periodic table are metals  Metallic minerals are normally combination of metallic elements.  Metals are extremely good conductors of electricity and heat and are not transparent to visible light. A polished metal surface has a luster appearance.  Metals are quite strong, yet deformable, which is account for their extensive use in structural applications.

Familiar objects made of metals CE SummerDr SaMeH7

CE SummerDr SaMeH Ceramics  Ceramics are compounds between metallic and non- metallic elements.  A ceramic material is an inorganic, non-metallic, often crystalline oxide, nitride or carbide material.  Ceramic materials are hard but very brittle. ( strong in compression, weak in shearing and tension).  Ceramics are generally made by taking mixtures of clay, earthen elements, powders, and water and shaping them into desired forms. Once the ceramic has been shaped, it is fired in a high temperature oven known as a kiln.  The wide range of materials that falls within this classification includes ceramics that composed of clay minerals, cement and glass.

CE SummerDr SaMeH Ceramics (cont.)  Ceramics materials are typically insulators to the passage of electricity and heat, and are more resistant to high temperatures and harsh environments than metals and polymers.  In general, ceramics are hard, wear-resistant, refractory, brittle, thermal insulators, electrical insulators, nonmagnetic, oxidation resistant, chemically stable.

CE SummerDr SaMeH Ceramics (cont.)  The properties of ceramic materials, like all materials, are dictated by the types of atoms present, the types of bonding between the atoms, and the way the atoms are packed together. This is known as the atomic scale structure. Most ceramics are made up of two or more elements.  The atoms in ceramic materials are held together by a chemical bond. The two most common chemical bonds for ceramic materials are covalent and ionic. For metals, the chemical bond is called the metallic bond. The bonding of atoms together is much stronger in covalent and ionic bonding than in metallic. That is why, generally speaking, metals are ductile and ceramics are brittle. Question!!

CE Summer Ceramics (cont.)

CE SummerDr SaMeH Polymers  Polymer is a large molecule, or macromolecule, composed of many repeated subunits.  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, ; furthermore they have a very large molecular structures.  These materials typically have low densities and may be extremely flexible.  There are S ynthetic and Natural polymers.  Natural polymer materials such as: amber, wool, silk and natural rubber.  S ynthetic polymer materials such as: synthetic rubber, resin, nylon, polyvinyl chloride.

CE SummerDr SaMeH Polymers (cont.) Common objects made from polymers: Plastic paper wareBilliard balls Bicycle helmet Two dice Lawn mower wheel Plastic milk carton

CE SummerDr SaMeH Composites  A " composite " is when two or more different materials are combined together to create a superior and unique material.  A composite is designed to display a combination of the best characteristics of each of the component materials.  Fiber glass is a familiar example, in which glass fibers are embedded within a polymeric material. For example: Fiberglass acquires strength from the glass and flexibility from the polymer.

CE SummerDr. SaMeH Composites (cont.)  Other examples of Composites  The most common example of a "composite“ is concrete. In this use, structural steel rebar provides the strength and stiffness to the concrete, while the cured cement holds the rebar stationary.  The composite material most commonly associated with the term "composite" is Fiber Reinforced Plastics. Common uses of fiber reinforced plastic composites are: Aircraft - Wind turbine blades Boats and marine - Building materials Bridges - Ladder rails Sporting equipment - Water pipes (Golf shafts, tennis rackets, hokey sticks, etc.)

CE Summer Dr. SaMeH Composites (cont.) Common composite objects Thermoplastic Fiber glass Hard rubber Wind turbine blades Water pipe

CE SummerDr SaMeH Semiconductors  Semiconductors have electrical properties that are intermediate between the electrical conductors and insulators.  The most common semiconductor materials are silicon and germanium.  Computer chips, both for CPU and memory, are composed of semiconductor materials.  Semiconductors make it possible to miniaturize electronic components, such as transistors. Not only does miniaturization mean that the components take up less space, it also means that they are faster and require less energy.

CE SummerDr SaMeH Semiconductors (cont.) Examples

CE SummerDr SaMeH Biomaterials  Biomaterials are employed in components implemented in the human body for replacement of damaged body part. (example: artificial joint )  Metals, ceramics, polymers, composites and semiconductors may be used as biomaterials. But it must not produce toxic substance and being compatible with the body.  Applications of Biomaterials:  Bone plates  Joint replacement  Dental implants for tooth  Heart valves  Contact lenses

CE SummerDr SaMeH Biomaterials (Cont.) Heart valve Contact lenses

CE SummerDr SaMeH Advanced Materials  Materials that are utilized in high–technology are sometimes called Advances Materials.  High-tech, here, means a device or product that operates using relatively sophisticated principles; example: CD players, Computers, Fiber optic systems, Aircraft, Spacecraft and Military rocketry.  Those advanced materials are either traditional materials whose properties have been enhanced or newly developed, high-performance materials. Furthermore, they may be of all material types ( metals, ceramics, polymers,..), and are normally relatively expensive.  Other examples: materials used for lasers, integrated circuits, magnetic information storage, liquid crystal display (LCD’s), etc.

Crystallization Crystalline materials - Materials in which the atoms are in a repeated 3D pattern. The repeated unit is called the unit cell. - At high temperatures, crystalline materials melt and become amorphous. Amorphous materials -Materials in which the atoms arranged almost randomly; or those that do not have a crystalline structure. -Example: glass CE SummerDr SaMeH Additional Material Classification

Brittle and Cementitious Brittle materials - Materials which little or no elongation or increase in length at fracture. -Examples: – cast iron – concrete – glass Cementitious materials -Materials in which the principle binder is cement. -Examples: – concrete – mortar CE SummerDr SaMeH Additional Material Classification

Material selection is based upon application, required materials properties, and budget. Applications can vary from electrical components to construction of large-scale civil engineering projects. Initial material property considerations consist of product function, environmental conditions and material degradation. Refined material selection is based upon: Technical and Structural analysis Examination of known and desired properties, such as : Physical, Mechanical, Thermal, Electromagnetic, Chemical. CE SummerDr SaMeH Material Selection

Improve your vocabulary and knowledge B rittle C ovalent D uctile I onic T hermal insulators E lectrical insulators N onmagnetic R efractory S tiffness CE SummerDr.SaMeH25 Important Terms C omposites B iomaterials C eramics S emiconductors P olymers

William D. Callister Jr, and David G. Rethwi Materials Sciences and Engineering “An Introduction, 9 th Edition. S. L. Kakani, Amit Kakani, (2004); “Material Science Dr. Oussama ElAlowi (CE212- lectures notes ), Civil and Environmental Engineering Department, MU CE SummerDr.SaMeH26 References