Engineering Materials Chemistry Reviewer PDF

ENGINEERING MATERIALS ❖ Understanding the properties (physical and chemical) of materials ❖ Designing (engineering) the structure of a material for a particular application or use ❖ Structure → Atomic structure, arrangement of atoms throughout the material ❖ Property → Chemical properti...

ENGINEERING MATERIALS ❖ Understanding the properties (physical and chemical) of materials ❖ Designing (engineering) the structure of a material for a particular application or use ❖ Structure → Atomic structure, arrangement of atoms throughout the material ❖ Property → Chemical properties (e.g. resistance to corrosion) → Physical properties (e.g. strength, flexibility) → Electrical and magnetic properties (e.g. conductivity) ❖ Processing → Manufacturing History ❖ Performance ❖ Metal ❖ Refractories ❖ Ceramic → ceramics that are designed to withstand very high temperature ❖ Polymers ❖ Alloys ❖ Composites → mixture of metals ❖ Composites → materials that are composed of two or more materials which combine to give a material superior than those of the individual component ENGINEERING MATERIALS ❖ Have definite volume ❖ An amorphous solid does not possess a ❖ Have definite shape well-defined arrangement and long-range ❖ Molecules are held in specific locations molecular order. → By electrical forces ❖ Vibrate about equilibrium positions ❖ Can be modeled as springs connecting molecules ❖ Crystalline → Regular, repeating geometric arrangement ❖ Amorphous → Random arrangements ❖ Melting point Crystalline solids → Sharp melting point, they change into liquids at definite temperature Amorphous solids → On heating, they do not turn abruptly into liquids, but instead, soften and start flowing in a semi-solid ❖ Crystalline solids’ molecules are arranged neatly forms in lattices of cells ❖ A unit cell is the basic repeating structural unit of ❖ Cooling Characteristics a crystalline solid. Crystalline Solids → Slow Cooled Amorphous solids → Fast Cooled Crystalline Solids → Diamond, Sodium chloride Amorphous solids ❖ At lattice points: → Glass → Atoms → Molecules → Ions ENGINEERING MATERIAL ❖ Ionic Crystals ❖ Tensile strength → Lattice points occupied by cations and anions ❖ Elasticity → Held together by electrostatic attraction ❖ Ductility → Hard, brittle, high melting point ❖ Malleability → Poor conductor of heat and electricity ❖ Brittleness ❖ Density ❖ Covalent Crystals ❖ Coefficient of Thermal Expansion → Lattice points occupied by atoms ❖ Specific heat/latent heat → Held together by covalent bonds ❖ Thermal/Electrical Conductivity → Hard, high melting point ❖ Hardness → Poor conductor of heat and electricity ❖ Magnetic Susceptibility ❖ Molecular Crystals → Lattice points occupied by molecules → Held together by intermolecular forces ❖ Chemical composition → Soft, low melting point ❖ Corrosion resistance → Poor conductor of heat and electricity ❖ Acidity or alkalinity ❖ Molecular/Crystal structure ❖ Metallic Crystals → Lattice points occupied by metal atoms → Held together by metallic bonds → Soft to hard, low to high melting point → Good conductors of heat and electricity  ALLOYS ❖ A partial or complete solution of one or more ❖ Manganese elements in a metallic matrix When added up to 1-1.5%, it Complete solid solution alloys increases toughness, → give single solid phase strength and brittleness Partial solution When added 11 – 14%, it → give 2 or more phases that may be homogeneous in imparts high degree of distribution depending on thermal properties strength ❖ Nickel ❖ Usually have different properties from those of the Improves corrosion and heat original components resistance, elasticity, toughness, ductility and tensile strength. ❖ Molybdenum Improves corrosion and abrasion resistance and strength at elevated temp; brittleness can be eliminated. ❖ Tungsten Improves toughness, abrasion and shock ❖ Chromium resistance and hardness at → improves hardness and toughness simultaneously higher temperature When added up to 12% : imparts high corrosion resistance When added up to 15%: enhances tensile strength ❖ Vanadium Improves tensile strength, ductility and shock-resistance POLYMERS ❖ Large molecules consisting of a long or chains of atoms covalently bonded ❖ Polymers are referred to as macromolecules → molecules of high molecular mass. ❖ Made up of monomers → small molecules used to synthesize the large polymeric chain ❖ Monomers add to the growing polymer chain in such a way that the product contains all the atoms of the starting material. ❖ No other product is formed ❖ LDPE- low density polyethylene ❖ HDPE – high density polyethylene ❖ PVC (or V)– polyvinyl chloride ❖ PS - polystyrene ❖ PP - polypropylene ❖ PET (or PETE) – polyethylene terephthalate ❖ ABS – acrylonitrile butadiene styrene ❖ PPO – polyphenylene oxide ❖ SAN – styrene acrylonitrile ❖ PBT – polybutylene terephthalate ❖ PEEK – polyether ether ketone ❖ PPS – polyphenylene sulfide ❖ PTFE – polytetrafluoroethylene ❖ LCP – liquid crystal polymer CERAMICS ❖ A wide-ranging group of materials whose ❖ Advanced Ceramics ingredients are clays, sand and feldspar. These materials have seen significant development over the past fifty years, with applications including: ❖ Clays → Rich in silicates, potassium,magnesium, and Structural components: Wear parts, engine calcium compounds. components, and armor. ❖ Sand Electrical applications: Capacitors and insulators. → Primarily consists of silica and feldspar or Coatings: Protecting tools and industrial parts. aluminum potassium silicate. ❖ Ceramic Armor Ceramic armor is utilized in military applications due to its lightweight yet strong properties. Typical ❖ Whitewares materials include alumina and silicon carbide. The → Includes crockery, tiles, sanitary ware, electrical design often features a hard outer layer that porcelain, and decorative ceramics. shatters projectiles, while an inner ductile layer absorbs residual energy. ❖ Refractories → Designed to withstand high temperatures (up to 2050°C), these materials are essential in industries like steel making and glass production. ❖ Glasses → Amorphous ceramics primarily made from silica; they can be tempered for increased toughness. ❖ Abrasives → Used for cutting and polishing, these can be natural (like diamond) or synthetic (like silicon carbide). ❖ Cements → Fundamental for construction, used in concrete for roads and buildings. ❖ Refractories are crucial for thermal protection in high-temperature applications. They typically have a porosity greater than 10% and contain oxides such as alumina and silica. Common uses include Fire Bricks for furnaces Thermal insulation in various industrial processes ❖ The main ingredient in Glass is silica (SiO2). Depending on the cooling process, glass can either be crystalline or amorphous. Types of glass include: Soda-lime glass Commonly used for windows and containers. Lead glass Enhances refractive index due to lead oxide. Borosilicate glass Known for its thermal resistance (e.g., Pyrex). NANOTECHNOLOGY ❖ Nanotechnology is the study of matter at an incredibly small scale, generally between 1 and 100 nanometers. ❖ 1 nm is 10^-9 of a meter. ❖ Nanotechnology encompasses a broad range of materials, manufacturing processes and technologies that are used to create and enhance many products that people use daily. NANOTECHNOLOGY NANOMATERIALS ❖ Materials having at least 1 dimension 100 nm or less. ❖ Temperature ❖ It can be nanoscale in 1 dimension (e.g. ❖ pH surface films); 2 dimensions (e.g. strands or ❖ Concentration fibers) or 3 dimensions (e.g. particles) ❖ Chemical Composition ❖ They can exist in single, fused or ❖ Surface modification agglomerated forms with spherical, tubular ❖ Process Control and irregular shapes. ❖ Top – down ❖ Class of allotrope of carbon which Refers to the mechanical crushing of source conceptually are graphene sheets rolled into materials using a milling process. tubes or spheres. These include the carbon nanotubes or silicon nanotubes which possess Nanomaterial is derived from a bulk substrate mechanical strength and electrical and obtained by progressive removal of conductivity material, until desired nanomaterial is ❖ FULLERENE obtained. Buckminsterfullerene, C60 (or buckyballs), resembles the balls used ❖ Bottom – up (chemo-physical production in association football process) In this method, nanomaterials are obtained starting from the atomic or molecular ❖ Allotropes of carbon with cylindrical precursors and gradually assembling it until nanostructure. the desired structure is formed. ❖ Exceptionally strong, and stiff ❖ Have extraordinary thermal conductivity, Structures are built up by chemical processes; mechanical and electrical properties. They based on physico-chemical principles of are added to various structural materials. molecular or atomic self-organization. This approach produces selected, more complex structures from atoms or molecules; ❖ Fabrication of nanomaterials includes better controlling sizes, shapes and size nanostructure surfaces, nanoparticles, range. nanoporous materials. Includes aerosol processes, precipitation reactions, and sol gel processes ❖ Particle Size ❖ Chemical Composition and desired feature of the nanomaterial ❖ Crystallinity ❖ A mechanical production approach to crush microparticles ❖ Applied in producing metallic and ceramic nanomaterials ❖ Involves thermal stress and is energy intensive ❖ Longer process (might contaminate the particles) ❖ A chemical or chemo-physical reaction accompanies the milling process NANOMATERIALS ❖ Most common industrial scale technologies for producing nanomaterials in powder or film form. ❖ Production of initial nanomaterials (liquid or solid) takes place via homogeneous nucleation ❖ Depending on the process, further particle growth ❖ Supramolecular structures are large molecules formed by grouping or bonding smaller molecules together ❖ Milling – breaking solid materials into smaller pieces by grinding, crushing, or cutting in a mill; a process of using rotary cutters ❖ Nucleation – initial process that occurs in the formation of a crystal from solution, a liquid or a vapor, in which smaller number of ions, atoms or molecules become arranged in a pattern characteristic of a crystalline solid, forming a site upon which additional particles are deposited as crystals grow. Wishing you all the best on your exam! -NARDO 🥳