Material Science Summary - Science Olympiad
Materials Science Study Notes
Page 1: Title
Materials Science
Instructor: Abby Hwang
Page 2: Event Format
Puck Testing
Teams must build a puck before competition.
Must submit a design log.
Pucks will be dropped from heights starting at 20 cm in 20 cm intervals.
Teams have 1 minute to prepare for each drop.
Written Test
Students can use a 2-sided note sheet inside a sheet protector.
Lab Activity
Required items: lab coat, goggles, N95 mask, calculator.
Page 3: Material Characteristics
Categories of Materials
Metals
Ceramics
Polymers
Composites
Page 4: Metals
Formed from metallic bonds:
Positively charged metal ions in a sea of delocalized electrons.
Electrons move freely.
Properties:
Low hardness, low corrosion resistance, high conductivity, high ductility, high density, high thermal conductivity, high boiling points, magnetic properties.
Page 5: Metallic Bonds
Composition
Delocalized electrons surrounding metal ions.
Page 6: Ceramics
Created by heating and then cooling clays or mineral compounds.
Composition: neither metallic nor organic; bonds can be ionic or covalent.
Key Properties:
Stiff, strong, hard, brittle, insulators of heat and electricity, chemically non-reactive, resist high temperatures and corrosion.
Page 7: Applications of Ceramics
Uses of Ceramics Beyond Pottery
Electronics, spark plugs, fiber optics, artificial joints, space shuttle tiles, cooktops, race car brakes, chemical sensors, body armor, skis.
Page 8: Glass vs. Ceramics
Structural Differences
Glass: Random structure.
Ceramics: Ordered, crystalline structure.
Common elements: Oxygen and Silicon.
Page 9: Polymers
Long chain molecules formed from monomers, can be natural or synthetic.
Properties: softening or decomposition at modest temperatures, lower stiffness and strength compared to metals and ceramics, low density, highly ductile and pliable, chemically inert, non-magnetic, poor conductors.
Page 10: Degree of Polymerization
Defined as the number of monomer units in a macromolecule or polymer molecule.
Page 11: Examples of Polymers
Teflon, rubber, plastic, polyester, sugarcane, DNA, RNA, wool.
Page 12: Composites
Combination of two materials with differing physical and chemical properties, resulting in a material specialized for a certain purpose.
Composite properties depend on their constituent parts—strength is influenced by fiber length and matrix construction.
Page 13: Composite Structure
Components
Fiber: Provides strength.
Matrix: Protects and transfers load.
Result: A material with superior attributes compared to individual components.
Page 14: Types of Composite Materials
Reinforced concrete (steel concrete), fiberglass (glass fibers in polymer resin), carbon fiber composites (carbon fibers in polymer resin), chipboard (wood chips and resin glue).
Page 15: Techniques & Occurrences
Discussion of methods used in materials science.
Page 16: Metals in Native and Combined States
Forms of Metals
Native States: Found in their elementary forms, e.g., gold, silver, copper, platinum (less reactive metals).
Combined States: Present in nature as compounds, e.g., oxides, carbonates, sulfides, phosphates (reactive metals).
Page 17: Mining Basics
Mining Process
Extracting useful materials from the earth involves various methods including caving, drilling, blasting, and managing ore.
Reference: H. Hamrin, Guide to Underground Mining Methods and Applications.
Page 18: Metal Forming
Definition
The re-shaping of metal into a desired form using force and different deformation methods.
Page 19: Forming Techniques
Hot working, forging, rolling, extrusion, drawing.
Page 20: Hot Working
Metal deformation occurs above recrystallization temperature.
Allows for increased malleability and is preferred when large deformations are needed.
Page 21: Forging
Description
Deforming a piece of hot metal using compressive forces, either through blows or continuous squeezing.
Results in superior grain structure and mechanical properties.
Page 22: Rolling
Passing a piece of metal between two rollers, either hot or cold.
Widely utilized deformation method.
Page 23: Extrusion
Forcing metal through a die to achieve desired shape with reduced cross-sectional area.
Products include rods and complex tubing.
Page 24: Drawing
Pulling metal through a die using tensile forces.
Page 25: Casting
Heating metal and pouring it into a mold to achieve a desired shape.
Page 26: Casting Techniques
Sand casting, die casting, investment casting, lost foam casting, continuous casting.
Page 27: Sand Casting
Most popular casting method using sand molds.
Allows for the creation of intricate objects and can be reused or destroyed after casting.
Page 28: Sand Casting Process
Diagram Overview
Riser & Runner: systems for pouring and flow; core box and pattern create mold; final cast part involves several steps: mold creation, pouring, and cooling.
Page 29: Die Casting
Methods
Ideal for metals with low melting points; molten metal is forced under high pressure into a mold.
Pros: rapid rates and cost-effective; Cons: limited to small pieces and certain alloys.
Page 30: Die Casting Diagram
Components Overview
Involves plunger, pressure chamber, ejection, and cover components.
Page 31: Investment Casting
Process
Wax or plastic pattern creates a mold which is then filled with a fluid slurry.
Used for applications needing high accuracy and detail.
Page 32: Investment Casting Process Diagram
Steps Overview
Involves pattern production, mold creation, pouring metal, and finishing processes.
Page 33: Lost Foam Casting
Description
Variation of investment casting using foam instead of wax, simplifying the investment process.
Benefits include complex geometries and reduced costs with fewer wastes.
Page 34: Lost Foam Casting Diagram
Overview
Visualizes the process of polystyrene pattern and molten metal integration.
Page 35: Continuous Casting
Details
Continuous pouring of molten metal into a cooled mold allowing solidification into billets or plates.
Highly automated but costly.
Page 36: Continuous Casting Diagram
Components
Tundish, submerged entry nozzle, and cooling elements comprise the process state.
Page 37: Ceramics Overview
Inorganic, nonmetallic materials that exist as crystalline or non-crystalline compounds.
Page 38: Ceramics Basics
Comprised of small repeating units forming crystalline structures that can exhibit ionic or covalent bonding.
Page 39: Crystalline Structure
Organized arrangement of atoms creates distinct properties in materials.
Page 40: Unit Cells
Definition
Repeating structures within crystalline solids compared to wallpaper patterns spanning dimensions.
Defined by lattice points where vibrational activities occur.
Page 41: Types of Crystal Structures
Structured Types
FCC (Face Centered Cubic)
BCC (Body Centered Cubic)
HCP (Hexagonal Close Packing)
SC (Simple Cubic)
Page 42: Atomic Packing & Coordination Number
Concepts Explained
Atomic Packing Factor (APF), coordination number, and their implications for material properties.
FCC has coordination number of 12; BCC has a coordination number of 8.
Page 43: Face Centered Cubic (FCC)
Properties
Densest cubic arrangement with atoms at corners and faces, total of 4 atoms per unit cell, APF of 0.74.
Page 44: Body Centered Cubic (BCC)
Characteristics
Contains 2 atoms per unit cell with a density lower than FCC, APF of 0.68, and coordination number of 8.
Page 45: Hexagonal Close Packing (HCP)
Structure
Combination of atoms forming alternating layers with an APF of 0.74 and coordination number of 12.
Page 46: Simple Cubic (SC)
Arrangement
Fundamental arrangement with one atom per unit cell, lowest density and coordination number of 6.
Page 47: Crystallinity
Definition
Degree of structural order indicating atomic arrangement within solids categorized into crystalline, poly-crystalline, and amorphous forms.
Page 48: Crystalline Definition
Ordered arrangements resulting in identifiable shapes and structures formed by unit cells.
Page 49: Poly-Crystalline
Properties
Mixture of crystalline and amorphous structures with true crystal portions.
Common in metals and ceramics to display mixed atomic arrangements.
Page 50: Amorphous Materials
Characteristics
Disorganized atomic structures resembling liquids; examples include gels, thin films, and glass.
Page 51: Mechanical Properties Overview
Density, hardness, elastic modulus, flexural strength, compressive strength, fracture toughness, brittle fracture.
Page 52: Mechanical Properties Explained
Key Attributes
Density: Mass per unit volume; influenced by atomic arrangement.
Hardness: Resistance to scratch and wear; related to atomic bond strength.
Elastic Modulus: Indicator of stiffness and return to original shape after stress.
Flexural Strength: Resistance to bending under load.
Compressive Strength: Resistance to compressive forces.
Fracture Toughness: Ability to absorb energy before fracturing.
Brittle Fracture: Sudden break without plastic deformation.
Page 53: Density
Importance
Influences interaction with forces; generally higher in tightly packed structures (e.g., metals) and lower in porous structures (e.g., polymers).
Page 54: Hardness
Details
Relates to material application, determined by atomic strength; diamond and ceramics show high hardness, while metals and polymers exhibit moderate to low hardness.
Page 55: Elastic Modulus
Description
Measures material's resistance to elastic deformation; influenced by bond types with stronger directional bonds yielding higher values.
Page 56: Flexural Strength
Importance
Important for applications subject to bending; materials with strong bonds exhibit high flexural strength.
Page 57: Compressive Strength
Definition
Critical for load-bearing materials; ceramics and metals usually possess high compressive strengths compared to polymers.
Page 58: Fracture Toughness
Implications
High toughness materials resist crack propagation; metals are generally tougher than ceramics due to ductility.
Page 59: Brittle Fracture
Characteristics
Occurs rapidly with little warning; common in ceramics and specific metals under low temperatures.
Page 60: Thermal & Electrical Properties Overview
Topics include heat capacity, thermal expansion, conductivity, and electrical insulation.
Page 61: Thermal Properties
Key Metrics
Heat Capacity
Thermal Expansion
Thermal Conductivity
Thermal Shock Resistance
Insulation capabilities.
Page 62: Heat Capacity
Definition
Amount of energy required to raise the temperature, influenced by atomic vibrations and molar mass.
Page 63: Thermal Expansion
Overview
Increase in material size due to temperature rise; weaker bonds lead to greater thermal expansion.
Page 64: Thermal Conductivity
Importance
Efficiency in transferring heat; metals exhibit high conductivity due to free electrons.
Page 65: Thermal Shock
Risks
Can lead to cracking with rapid temperature changes; ceramics often suffer due to their rigidity.
Page 66: Insulation
Definition
Resistance to heat/electricity flow; dependent on atomic structure and mobility of particles.
Page 67: Electrical Conductivity
Description
Ability to allow current to pass; commonly low in ceramics due to tightly bonded structures.
Page 68: Piezoelectricity
Explanation
Generation of charge in solid materials under mechanical stress; utilized in various sensor applications.
Page 69: Dielectric Properties
Details
Indicate material’s capacity to store energy in electrical fields; quality can degrade under high fields.
Page 70: Van der Waals Forces
Characteristics
Weak attractions between neutral molecules, significant for gas and organic liquids.
Page 71: Defects & Imperfections Overview
Importance
Defects play a crucial role in determining physical and chemical properties of materials.
Page 72: Categories of Defects
Types
Classified by geometry: Point, Linear, Interfacial.
Page 73: Point Defects
Explanation
Localized disruptions involving one or two atoms, including vacancies, interstitials, and impurities.
Page 74: Linear Defects
Description
One-dimensional disruptions like edge dislocation and screw dislocation affecting crystal structure.
Page 75: Interfacial Defects
Characteristics
Two-dimensional defects at boundaries including grain boundaries, twin boundaries, and phase boundaries.
Page 76: Porosity
Definition
Voids within materials, indicating ratio of pore volume to the total volume.
Page 77: Archimedes's Method
Volume Measurement Technique
Compares dry and submerged weights to determine material volume and pore space.
Page 78: Mercury Intrusion Porosity
Overview
Measures pore size and porosity using mercury under pressure.
Page 79: Gas Pycnometry
Technique
Employs gas displacement for measuring solid volume and open porosity.
Page 80: Chemistry Review Quizzes
Resource Links
Various quizzes and reviews available at specified links.
Page 81: Study Resources
Additional Links
eg. SciOly Wiki Page, Practice Tests, Quizlet, more useful for exam prep.