MATSCIE TOPIC 1_compressed.pdf

WHAT IS MATERIALS SCIENCE?  MATERIAL SCIENCE involves investigating the relationships that exist between the structures and properties of materials. WHAT IS ENGINEERING MATERIALS ?  ENGINEERING MATERIALS On the basis of these structure property correlations, d...

WHAT IS MATERIALS SCIENCE?  MATERIAL SCIENCE involves investigating the relationships that exist between the structures and properties of materials. WHAT IS ENGINEERING MATERIALS ?  ENGINEERING MATERIALS On the basis of these structure property correlations, designing or engineering the structure of a material to produce a predetermined set of properties.  MATERIALS DEVELOPMENT Materials are probably more deep-seated in our culture than most of us realize. Transportation, housing, clothing, communication, recreation, and food production virtually every segment of our everyday lives is influenced to one degree or another by materials.  MATERIALS DEVELOPMENT Historically, the development and advancement of societies have been intimately tied to the members’ ability to produce and manipulate materials to fill their needs. In fact, early civilizations have been designated by the level of their materials development (Stone Age, Bronze Age, Iron Age). 1. Stone Age (beginning life – 3000 BC) - using naturally occurring materials with only changes in shape 2. Bronze Age (3000 BC – 1200 BC) – Copper and Tin Alloy -ability to modify materials by refining (using heat), chemical modifications (alloying) and mechanical deformation (cold working) 3. Iron Age (1200 BC – Present) - Casting and alloying weren’t perfected until 16th century Mastery of Steel (Iron alloy) technology enables Industrial Revolution in the 18th and 19th century Ability to heat treat at high temperature, control microstructure at different length scale and ability to design specific microstructures for specific properties 4. Plastic Age (1940 – Present) - Discovery of polymers, and the ability to synthesize and process polymers. 5. Silicon Age (1950 - Present) - Commercialization of silicon technology (integrated circuits, electronic devices, etc…) leads to the information age, which gives boost to human productivity - Ability to control alloying accurately, ability to make thin films. 6. Future Nanotechnology - Synthesis and characterizations of nanomaterials and nanostructure Biotechnology - biomimetics and biomaterials Energy/Environmental - Next generation energy conversion Information Technology - Materials informatics NATURE OF MATERIALS 1.Types of Engineering Materials 2.Engineering Materials Composition 3.Bonding and Molecules  TYPES OF ENGINEERING MATERIALS ENGINEERING MATERIALS - It used as raw material for any sort of construction or manufacturing in an organized way not only in the field of engineering, but in a day-to-day basis because of their properties and characteristics. - These materials enable people to explore in the design and implementation of new products to improve the quality of our modern life. - Proper study of these materials is necessary in order to exploit all the great characteristics that makes us want a better lifestyle.  COMMON TYPES OF ENGINEERING MATERIALS (1) METALS (2) PLASTICS (3) CERAMICS (4) COMPOSITES POLYMER  (1) METALS - These are opaque, lustrous elements that are good conductors of heat and electricity.  5 COMMON CHARACTERISTICS AND PROPERTIES OF METALS 1. HIGH MELTING POINT - There will be more heat required to melt a particular substance from solid to liquid state. 2. DUCTILITY - It is the quality of being pliable and flexible, like a piece of metal that can be bent into a thin wire. 3. MALLEABILITY - It is the ability of a substance, usually a metal, to be deformed or molded into a different shape. 4. CONDUCTIVITY - The metals are a good conductor of heat and electricity as they can pass through them. 5. LUSTER - It is gentle shining light that is reflected from a surface. COMMON TYPES OF METALS (1.1) Ferrous Metals - Those in which iron is the prime constituent are produced in larger quantities than any other metal type. - They are especially important as engineering construction materials.  EXAMPLES: (1.1.1)STAINLESS STEELS – HIGHLY RESISTANT TO CORROSION  (1.1.2) CAST IRONS Mostly, carbon exists as graphite. Microstructure and mechanical behavior depend on composition and heat treatment. Gray Iron - It is used for housings where the stiffness of the component is more important than its tensile strength, such as internal combustion engine cylinder blocks, pump housings, valve bodies, electrical boxes, and decorative castings (1.2) NON-FERROUS METALS Metals that are those which contain no iron. All non-ferrous alloys do not share a common property; it varies according to the composition and the heat treatment method in producing the alloy.  EXAMPLES: (1.2.1) Aluminum – It is used in a huge variety of products including cans, foils, kitchen utensils, window frames, beer kegs and aeroplane parts. (1.2.2) COPPER - ideal for use in home appliances, transportation equipment, electronic products, electrical grids, building construction. (2) PLASTICS It is used across almost every sector. To produce packaging, in building and construction, transportation and etc. 5 COMMON CHARACTERISTICS AND PROPERTIES OF PLASTICS 1. Chemical resistance - Plastics offer great resistance to moisture, chemicals and solvents. 2. Durability - polymers that can be softened through heating before being processed and then left to cool and harden. Such as thermoplastic varieties such as polyethylene, common plastic mostly used for packaging. 3. Dimensional stability - measure of a material's ability to retain its fit, form, and functional properties throughout its lifecycle. 4. Fire protection - Plastics, being organic in nature, are combustible. But the resistance to fire temperature depends upon the plastic structure. 5. Insulation - Plastics exhibit good electrical and thermal insulation properties, making them suitable for use in electrical components and wirings.  TYPES OF PLASTICS (2.1) THERMOPLASTICS – can be melted repeatedly. (2.1.1) ACRYLICS (2.1.2) NYLONS (2.1.3) PVC (2.2) THERMOSETS – once shaped, cannot be melted. Examples: (2.2.1) Epoxy resin (2.3) Elastomers – type of elastic material. It can be stretched to many times their original length. Examples: (2.3.1) Rubbers (2.3.2) Silicones  (3) CERAMICS Inorganic, nonmetallic materials that consist of metallic and nonmetallic elements bonded together primarily by ionic and/ or covalent bonds. Its chemical compositions vary considerably, from simple compounds to mixtures of many complex phases bonded together. Ceramics used for engineering applications, can be divided into two groups: 1) Traditional ceramic materials 2) Advanced ceramic materials  5 COMMON CHARACTERISTICS AND PROPERTIES OF CERAMICS 1. Chemical resistance - Ceramics are highly resistant to chemical corrosion, allowing them to be used in industries where exposure to harsh chemicals is common. 2. Hardness - Defined by its chemical composition, including porosity, grain size, and grain- boundary phases. 3. High melting point - Ceramics exhibit exceptionally high melting points, often surpassing those of metals and polymers. 4. Limited ductility - Conventionally brittle ceramics became ductile permitting large (~100%) plastic deformations at low temperature if a polycrystalline ceramic was generated with a crystal size of a few nm. 5. Thermal conductivity - They are brittle, have low thermal conductivity, and offer corrosion resistance, making them essential in various industries, from electronics to aerospace. TYPES OF CERAMICS (3.1) Traditional ceramic materials Examples: (3.1.1.) Glass - Ceramic glass is a mechanically strong and versatile material. It can sustain vast temperature changes and is not porous, making it an ideal material. (3.1.2) Clay - one of the most widely used ceramic raw materials. It is found in great abundance and popular because of the ease with which products are made. (3.2) ADVANCED CERAMIC MATERIALS Examples: (3.2.1) Diamond (C) It is the hardest material known to be available in nature. It has many applications such as industrial abrasives, cutting tools, abrasion-resistant coatings, etc. It is, of course, also used in jewelry. (3.2.2) Titanium Oxide (TiO₂) - it is mostly found as a pigment in paints. It also forms part of certain glass ceramics. It is used to make other ceramics like BaTiO₃. (4) COMPOSITES These are mixtures of two or more bonded materials. These composites are the mixture of multiple materials, which in combination offer superior properties to the materials alone. Structural composites usually refer to the use of fibers which are embedded in a plastic. These composites offer high strength with very little weight.  5 COMMON CHARACTERISTICS AND PROPERTIES OF COMPOSITES 1. Chemical resistance - determined by the choice of resin and reinforcement used within the composite application. 2. Electrical conductivity - Upon synthesis, the composite is ionically conductive due to the dissolution of ions from the Borax and the presence of metal fillers. 3. Fire resistance - The inert fibre-reinforcement displaces polymer resin during fire and thus removes fuel for the fire. 4. Flexibility - Allows composites to have precise performance properties to suit any given application, with typical product focuses on floors, ceilings and partitions. 5. Lightweight - their individual components have low density and superior strength and stiffness. EXAMPLES OF COMPOSITES (4.1)Ceramic Matrix Composites - ceramic matrix coupled with embedded ceramic fibers. This unique association of materials revolutionized the aerospace (4.1)Carbon-fiber reinforced - Reinforcement: provides rigidity and resistance. Composite materials examples. Plastics reinforced with glass fibre or other fibres. (4.3) WOOD-PLASTIC COMPOSITE Also known as engineered wood. Composite wood is a mixture of several components that may include wood, plastic and straw. Composite woods are often used in cabinets, furniture, sheathing, flooring and siding. ENGINEERING MATERIALS COMPOSITION ENGINEERING MATERIALS COMPOSITION Knowing the composition of engineering materials is crucial because it helps engineers select the right materials for specific applications, ensuring optimal performance, safety, and durability. It affects factors like cost, manufacturability, efficiency, and sustainability, allowing for better decision-making in project design and production. Additionally, it ensures compliance with industry standards and regulations, ultimately leading to reliable and long-lasting solutions.  ATOMS We used to say that the atom was the smallest unit of which matter was composed and indivisible. Also, the atom is considered as the basic structural unit of matter. ATOMIC STRUCTURE Each atom consists of a very small nucleus composed of protons and neutrons, which is encircled by moving electrons. Both electrons and protons are electrically charged, the charge magnitude being 1.60x10⁻¹⁹ C, which is negative in sign for electrons and positive for protons; neutrons are electrically neutral. ATOMIC STRUCTURE Masses for these subatomic particles are infinitesimally small; protons and neutrons have approximately the same mass, 1.67 x 10⁻²⁷ kg, which is significantly larger than that of an electron, 9.11 x10⁻³¹ kg. ATOMIC STRUCTURE Atoms have three basic particles: 1. Proton 2. Neutron 3. Electron The protons and neutrons are found inside the nucleus. The electrons orbit the nucleus on shells. When the atoms have gained or lost one or more electrons, it is called as IONS. Losing of an electron makes the atom While gaining an electron makes the atom electropositive since there will be a positively electronegative since there is no spare positively charged proton without its balancing electron. charged proton in the nucleus to balance the additional Such an ion is called POSITIVE ION. electron. Such an ion is called NEGATIVE ION. CATION & ANION  COMMON TYPES OF ENGINEERING MATERIALS AND THEIR TYPICAL COMPOSITIONS: METALS Ferrous metals: Primarily contain iron (Fe), with carbon (C) and other elements like chromium (Cr) or nickel (Ni) added for enhanced properties (e.g., steel). Non-ferrous metals: Do not contain iron. Common examples include aluminum (Al), copper (Cu), and titanium (Ti), often alloyed with other elements for specific qualities. POLYMERS Made of long chains of organic molecules (usually carbon and hydrogen). Common polymers include polyethylene, polypropylene, and PVC, which consist of repeating units of monomers like ethylene or vinyl chloride. CERAMICS Composed of inorganic compounds like oxides (Al2O3), nitrides (Si3N4), or carbides (SiC). These materials are known for their hardness, heat resistance, and brittleness.  COMMON TYPES OF ENGINEERING MATERIALS AND THEIR TYPICAL COMPOSITIONS: COMPOSITES Made by combining two or more materials to achieve improved properties. Common composites include carbon fiber-reinforced polymers (CFRP), where carbon fibers provide strength while the polymer matrix adds flexibility. ALLOYS Mixtures of metals, where at least one element is metal. For example, brass is an alloy of copper (Cu) and zinc (Zn), while stainless steel is an alloy of iron (Fe), chromium (Cr), and sometimes nickel (Ni) BONDING OF ATOMS When two or more atoms, either of one type or different types of atom, are joined together chemically, the unit which is produced is called a molecule. This process is called chemical bonding. CHEMICAL BONDING Atoms are stable when they have 8 valence electrons. When the atoms have 8 electrons, it is called an octet. Atoms must lose, gain or share electrons to attain the octet.  PRIMARY INTERATOMIC BONDS 1.Ionic Bonding 2.Covalent Bonding 3.Metallic Bonding  IONIC BONDING Atoms are like tiny building blocks of matter, and they have smaller particles called electrons that orbit around them. Atoms want to be stable, and they do this by having a full outer shell of electrons. Some atoms need to lose electrons to become stable, while others need to gain them. When an atom loses or gains electrons, it becomes an ion. An atom that loses electrons becomes a positively charged ion (because it has more protons than electrons), and an atom that gains electrons becomes a negatively charged ion (because it has more electrons than protons). Opposite charges attract each other. So, a positively charged ion and a negatively charged ion will be drawn together, forming an ionic bond. This bond is the force that holds the two ions together. IONIC BONDING COVALENT BONDING Atoms are more stable when they have a full outer shell of electrons. In a covalent bond, instead of transferring electrons, atoms share one or more pairs of electrons so that each atom can fill its outer shell. When atoms share electrons, they become bonded together, forming a molecule.  METALLIC BONDING Metals are made up of atoms that are closely packed together. In metallic bonding, the outer electrons of metal atoms become free to move throughout the entire structure. These free electrons are not bound to any specific atom. The metal atoms release some of their electrons, creating a "sea of electrons" that flows around the positively charged metal ions (the atoms that lost electrons). This "sea of electrons" acts like glue, holding the metal atoms together. It also gives metals their unique properties, such as the ability to conduct electricity, be malleable (easily shaped), and have a shiny appearance. METALLIC BONDING HOW DO WE KNOW IF IT IS COVALENT OR IONIC?  Atoms or molecules can have slight SECONDARY imbalances in their electron distribution, even if they are neutral overall. This creates BONDING / tiny, temporary positive and negative charges. VAN DER WAALS These temporary charges cause nearby BONDING atoms or molecules to be attracted to each other, forming a weak bond. This attraction is what we call Van der Waals bonding. Dispersion Forces: Found in all molecules, especially non-polar ones, due to temporary shifts in electron clouds that create tiny dipoles. Dipole-Dipole Interactions: Occur between TYPES OF molecules that have permanent dipoles, like in polar molecules (where one side is slightly positive VAN DER WAALS and the other is slightly negative). FORCES: Hydrogen Bonds: A specific and stronger type of dipole-dipole interaction involving hydrogen atoms bonded to electronegative atoms like oxygen or nitrogen.