Material Properties & Applications Lecture Notes

Material and Application

  • Physical Properties: Observable characteristics; how a material reacts to external changes.

    • Density: Mass per volume; affects weight.

    • Thermal Conductivity: How well a material conducts heat.

    • Electrical Conductivity: How well a material allows the flow of electric current.

    • Magnetism: Ability to attract or be attracted by a magnetic field.

    • Corrosion Resistance: Ability to resist oxidation and rust.

    • Thermal Expansion Rate: How much a material expands with heat.

    • Chemical Stability: Ability to resist reacting with other materials.

    • Flammability: How easily a material catches fire.

    • Transparency: Allows light to pass through clearly.

    • Translucency: Allows light to pass through, but diffuses it (semi-clear).

    • Opacity: How much light is allowed through (fully opaque).

    • Luster: How smooth and shiny something is.

    • Color: Influences design choices.

    • Texture: Surface finish; affects appeal.

  • Mechanical Properties: How materials react to forces.

    • Toughness: Ability to absorb energy and withstand impact.

    • Strength: Ability to withstand force without breaking.

    • Elasticity: Ability to return to its original shape after deformation.

    • Malleability: Ability to be deformed under pressure.

    • Plasticity: Ability to be permanently deformed without breaking.

    • Ductility: Ability to withstand pulling forces for a long time.

    • Hardness: Resistance to scratching.

Material Properties

  • Traditional Materials: Materials that have been used for centuries.

  • Smart Materials: Materials that change properties.

  • Biodegradable: Ability to decompose naturally.

  • Recyclability: Ability to be repurposed after initial use.

  • Sustainability: How materials affect the environment throughout their lifecycle.

  • Mechanical Properties Classification: Force applied and material reaction.

    • F=ForceF = Force

    • A=AreaA = Area

    • σ=Stressσ = Stress

    • E=Young′sModulusE = Young's Modulus

    • Compression: Ability to withstand squeezing forces.

    • Tension: Ability to withstand stretching forces.

    • Shear: Ability to withstand sliding forces.

    • Torsion: Ability to withstand twisting forces.

    • Bending: Ability to withstand forces that attempt to bend the material.

    • Tensile Strength: Ability to withstand stretching.

    • Compressive Strength: Ability to withstand compression.

    • Shear Strength: Ability to withstand sliding.

    • Torsional Strength: Ability to withstand twisting.

    • Bending Strength: Ability to withstand bending forces.

Wood and Timber

  • Softwood: From coniferous trees.

    • Evergreen trees that keep their leaves all year.

    • Less dense, faster-growing.

    • Lighter, less durable.

    • Cheaper.

  • Hardwood: From deciduous trees.

    • Trees that lose their leaves annually.

    • Slower growing.

    • Strong.

    • Dense.

    • Expensive.

    • Durable.

    • Heavier (denser/harder wood).

  • Process of Wood Copping: Cutting down trees, which can regrow from their stumps, allowing continued harvest.

  • Knots: Natural imperfections caused by the growth of branches.

    • Live Knots: Connected and free from the growth ring.

    • Dead Knots: Detached from the growth ring.

Tangential Sawing

  • A method of cutting timber.

  • Manufacture boards

Seasoning

  • Process to remove excess moisture from timber to increase strength and durability.

    • Air Seasoning: Wood stacked in a well-ventilated area, sheltered from the weather, to dry over months or years.

      • Inexpensive.

      • Slow process.

      • Reduces warping.

    • Kiln Seasoning: Temperature and humidity controlled to speed up drying, taking days or weeks.

      • More stable process.

Stock Form of Timber

  • The shapes and sizes in which timber is prepared for use.

Metals and Alloys

  • Metals: Materials containing iron (ferrous) or not (non-ferrous).

  • Alloys: Combinations of two or more metals to enhance properties.

Ferrous Metals

  • Contain Iron.

    • Cast Iron (2-4% Carbon).

      • Hard and brittle.

      • High compressive strength.

      • Resistant to deformation.

      • Uses: Heavy-duty cookware.

    • Low Carbon Steel (0.05-0.3% Carbon).

      • Durable, ductile, malleable. Good tensile strength.

      • Uses: Car bodies.

    • Medium Carbon Steel (0.3-0.7% Carbon).

      • Harder than mild steel, but less ductile.

      • Uses: Gardening tools.

    • High Carbon Steel (0.7-1.7% Carbon).

      • Very Strong and Hard, less ductile.

      • Uses: Drills.

    • Stainless Steel.

      • Corrosion resistant, hard, high tensile strength, temperature resistant.

      • Uses: Cutlery, kitchen sinks.

Non-Ferrous Metals

  • Do not contain Iron.

    • Aluminum.

      • Lightweight, corrosion-resistant, malleable, good conductor.

      • Uses: Aircraft parts, cans, kitchen foil.

    • Copper.

      • Excellent conductor of heat/electricity, ductile, malleable.

      • Uses: Electrical wiring.

    • Zinc.

      • Corrosion-resistant, brittle, malleable at high temperatures.

      • Uses: Batteries, castings.

    • Tin.

      • Soft, corrosion-resistant, ductile.

      • Uses: Coating for steel cans, solder, foil.

    • Titanium.

      • High Strength-to-Weight Ratio, corrosion resistance, high melting point and heat resistance, hard.

      • Uses: Aviation, high-performance sports equipment.

    • Lead.

      • Heavy, soft, malleable.

      • Uses: Radioactive containers.

Polymers

  • Thermoplastic

    • Can be softened, reshaped, and recycled repeatedly.

      • Polyethylene (PE): Plastic bags/bottles.

      • Polypropylene (PP): Food containers.

      • Polymethyl methacrylate (PMMA): Display screens, aquariums.

      • Polyvinyl Chloride (PVC): Pipes, cable insulation. Not good electrical conductivity.

      • Polystyrene (PS): Packaging, disposable cups.

  • Thermosetting

    • Hardens permanently when heated; cannot be reshaped/recycled after initial shaping.

      • Epoxy Resin: Electrical insulator.

      • Polyester Resin: Car bodies, waterproof coatings.

      • Melamine Formaldehyde: Kitchen worktops.

  • Elastomer

    • Polymer with properties of Thermosetting.

    • Can return to original shape after being deformed.
      *Recyling Polymers:

    • Thermoplastics are reliably recyclable.

    • Thermosetting polymers cannot be remolded or reheated which makes them NOT recyclable.

  • Properties of Polymers

    • Thermoplastic: Long chains of molecules make it flexible and allow it to be reshaped. Cooled, resulting in a rigid solid material.No links between monomers which helps movement.

    • Thermosetting: Has links between monomers.

    • Ideal for transport.

      • Durable and resistant to chemical uses.

      • Flexible, suitable for various shapes.

      • Insulative, good thermal/electrical.

Elastomers and Biopolymers

  • Elastomers: Flexible, even when cooled; good elasticity, wear resistance, hardness, thermal resistance and oil resistance, can be tough and flexible with good weather resistance. Specialized materials are sometimes added.

    • Natural Rubber: Used for tires and rubber bands. Good elasticity and wear resistance but limited delegation time and good hardness.

    • Neoprene: Used in laptop cases; good oil resistance, toughness, and flexibility with good weather resistance.

    • Silicone Rubber: Flexible for low temperatures, waterproof, and used in medical tubing.

    • Biopolymers: Have links between monomers, are biodegradable, and some are water-soluble.

      • Oxy-degradable Polymer: Breaks down through oxidation.

      • Photodegradable Polymer: Breaks down when exposed to light.

      • Bio batch: A specialized material added to polymers to enhance biodegradability.

      • Water Soluble Polymer: Dissolves in water, for example in laundry bags, has limited delegation time.

Ecological Footprint of Polymers

  • Resources Extraction and Processing: Fossil fuels are used, many polymers are derived from non-renewable sources, and high energy consumption occurs, leading to waste and pollution.

    • CO2CO_2 emissions.

    • Non-biodegradable: Polymers continue to landfill and ocean pollution.

  • Solutions:

    • Use biopolymers for lighter weight and cost-effectiveness.

    • Recycled polymers.

  • Social Footprint of Polymers: Health and safety risks due to toxic chemicals and pollution during manufacture.

  • Ethical Considerations: focus on worker conditions, sources of materials (bio-based polymers).
    Community input, waste absorb local community.

Paper and Board

  • Optical Properties: How paper interacts with light; brightness, opacity, color, gloss (how shiny).

    • Opacity: How much light passes through.

    • Gloss: How shiny it is.

  • Thickness: Measured in microns.

  • Surface Properties: Properties of the surface; finish, smoothness, porosity (how much paper absorbs moisture).
    *Finish:How the material looks,feel, texture etc

  • Strength: Tensile strength (stretch), bending strength (flexible).

  • Common Stock Paper Sizes: A0 (largest), A1 (artwork, posters), A2 (smaller artwork), A3 (D&T projects), A4 (booklets), A5 (leaflets/flyers), A6 (postcards), A7 (labels), A8 (business cards).

  • Paper Composition: Cellulose + coating (clay or chalk to achieve a smooth surface) + sizing agent (improves ink absorption).

  • Laminating: Layering thin card stock together.

  • Transparent: Compress Grease proof paper

  • Tracing paper & layout:
    Change finish

  • How to Judge Paper Quality & Cost

    • Newspaper ~ Cheaper

      • Photo paper ~ More expesive
        Brightness ~ How white and brighter the paper is
        Finish ~ How material looks and feels
        Thickness ~ how tick the paper
        Paper strength ~ How strong is the paper.
        Perfume Cartoons ~ Stronger

Types of Board

  • Difference Between Paper, Card, and Board: Thickness and weight. Paper (<200 gsm), Card (200-500 gsm), Board (>500 gsm). 1000 micrometers = 1mm.

    • Inkjet Card: High-quality card treated for inkjet printers.

    • Cardboard: Cheap, recyclable, sturdy board for packaging.

    • Whiteboard: Strong, bleached, great for printing.

    • Duplex Board: Cheaper whiteboard alternative, brown on one side. Two layers with different color/finish, often for food packaging.

    • Tracing Paper: Translucent paper, slightly thicker than layout paper. Used to copy images.

    • Layout Paper: Translucent paper with a smooth surface used for sketching and technical drawings.

    • Bleed-Proof Paper: Protective layer underside to stop ink bleed; used for marker work.

    • Corrugated Board: Corrugated layer gives thickness and strength for packaging.

    • Cartridge Paper: Ideal for general writing/drawing on printer and laser copies, bleached card.

    • Greeting Card: Have a smooth surface.

    • Foil-Backed Card: Gold with metallic surface used for takeaway food lids and has metal effects.

    • Lenticular card:Holographic Effect when turned in light. Gift Pacakging

      • Duplex cord: For printing photos

      • COated paper: High cord with creative resistive metal surface

    • Limit less amout of ink is observed into the paper
      Watercolored Paper: High quality card with water color painting, unlike Cartridge paper

Lamination and Composite Materials

  • Lamination: Polymer attached to one or two sides, e.g., drink package (Polyethylene/Aluminum laminated on the card).

  • Composite Material: A mix of two or more materials to get better properties (e.g., concrete = cement + sand + water + stone).

  • Laminated Board: Glue holds everything together and improves properties. Examples include reinforcement (steel bar in concrete) and fiber or particle-based sheets.

  • Application of Board: Mounting board (thick and lightweight), sign, chipboard, MDF, foam board (thin with foam core, white outside, or colored).

    • Fiber-Based Material: GRP (Glass reinforced plastic - boats/cars), carbon-reinforced plastic (carbon + plastic - colored/race cars), Kevlar (bulletproof vests).

    • Particle-Based Material: Concrete (cement + sand + stone - bridges/buildings), cermet (ceramic + metal - cutting tools).

  • Fibre Based Board:
    Ply Wood ~ layers thick ( Glass/carbs)
    Card Board ~ Grey Ridgely no bonding
    Corrugated cardboard~ layer of card with corrugated core

How Composite Materials are Made

  • Lay-Up Process: Prepare clean surface material needed.

    • Sheet-Based (Laminate): Cut computer file, layer glue together for big shapes.

    • Laying Fiber (Glass/Carbon): Layering glass/carbon fiber, add resin (glue) to the fiber, consolidate (roll, brushes to remove air bubbles and ensure even distribution), cure to harden, trim to cut off excess.

    • Veneer: Layer of glue at 90-degree angle > laminate > stronger wood beam for construction.

    • Consolidation: Distribute even
      Properties of Composite Material

  • Properties of Composite Materials

    • Consist in Roll, brushes removes the air bubbles Ensure strong bonds!

    • Strong but lightweight: Used planes/race cars, can be molded to any shape
      Corrosion Resistance
      Waterproof
      Wont rust (GRP used in boat is resistance.
      GBR ~ Used in boat resist on most
      GRP ~ spray chopped fibrecand spray a product to stick well together

    Layering more

    Durability
    Shape memory
    Can be molded to any shape
    Won't Rust