Evolution and Classification of Materials

Posted on Nov 26, 2024 in Geology

History and Evolution of Materials

Stone Age

  • Paleolithic: Discovery of fire
  • Neolithic: Development of pottery

Age of Materials

  • Copper Age: Metallurgy of copper, silver, and gold
  • Bronze Age: Copper-tin alloys, improved copper properties
  • Iron Age: Discovery of steel (cast iron with carbon), discovery of glass

New Materials

  • Construction: Wood, concrete (20th century)
  • Metal: 18th century – Necker and soft iron, steel, foundry. 19th century – aluminum. 20th century – titanium.
  • Polymer: 19th century – rubber, 20th century – bakelite
  • Ceramic: Advanced bioceramics
  • Electronic: Silicon era

Classification of Materials

  • Metal: Ferrous / Non-ferrous
  • Polymers: Thermoplastic / Thermoset / Elastomer
  • Stony
  • Ceramic: Conventional / Advanced
  • Composites
  • Timber: Natural / Processed
  • Binders
  • Textiles: Natural / Artificial
  • Glass

Metallic Materials (Ferrous)

Materials containing one or more metallic elements, may also contain non-metals.

Properties

  • High thermal and electrical conductivity
  • Mechanical strength
  • Plasticity (deformation before rupture)
  • Malleability (conversion into plates)
  • Ductility (transformation into wire)

Classification

  • Ferrous Materials: High iron percentage, magnetic properties. Examples: Steel and cast iron.
  • Non-ferrous Metals: No iron. Subdivided into:
    • Heavy Metals: Copper, tin, lead, mercury, nickel, chromium, tungsten
    • Lightweight Materials: Aluminum and titanium

Classification of Steels

Carbon Steels

  • Sweet Steel (Low-carbon <0.2%, fully ductile)
  • Medium Steel (0.2% – 0.6% carbon, used for rail and construction)
  • High-carbon Steel (High carbon content, hard and brittle. Obtained by heating steel at very high temperatures and rapid cooling. Used for surgical instruments, cutlery, razor blades)

Special Alloy Steel

Small amounts of other elements (e.g., nickel, chromium) added to steel for specific properties.

  • Manganese Steel: Very stiff and resistant, used in safes.
  • Chrome Vanadium Steel: High mechanical strength, used in axles and car parts.
  • Nickel Chromium Steel: Very hard, used in shields and stainless cookware.

Non-ferrous Metals

Heavy Metals

Copper

  • Hard, bends easily, corrosion-resistant
  • Excellent conductor of electricity and heat
  • Used in electrical conductors (wires, coils) and heating/gas pipes
  • Alloys: Bronze (copper and tin), Brass (copper and zinc)

Applications

  • Bronze: Fittings, machine components, sculptures
  • Brass: Caps, locks, interior design, electrical contacts, jewelry

Other Heavy Metals

Tin

  • Very soft, ductile, malleable, easily melted
  • Used in solder for plumbing, electricity, electronics, and bronze production

Zinc

  • White, fragile, easily oxidized (but forms a protective layer)
  • Used in building decks, warehouses, galvanized steel, gutters

Light Metals

Aluminum

  • One of the lightest metals
  • Acceptable mechanical strength
  • Good conductor of heat and electricity
  • Easily workable
  • Used in aerospace, machine parts, containers, utensils
  • Alloys: Duralumin (aluminum, copper, magnesium, silicon), Aluminum-magnesium alloys

Titanium

  • Abundant, hard as steel but much lighter
  • Higher mechanical strength than aluminum (but heavier)
  • Corrosion-resistant, non-toxic, biocompatible
  • High production costs
  • Applications: Aerospace (rocket engines, spacecraft, fuel tanks), commercial aircraft turbines, medicine (bone fracture repair, dental implants)

Corrosion

Chemical or electrochemical reaction of a metal or alloy with its environment, leading to deterioration.

Causes

  • Volatility of metals
  • Metals found in nature in combined form
  • Corrosion products are more stable than pure metals

Processes

  • Moist air and oxygen lead to metal oxides and rust
  • Compact and waterproof layer formation in some metals (e.g., aluminum, zinc, copper)

Methods of Protection

  • Careful Material Choice: Depends on the application. Nickel alloys for oxidizing conditions.
  • Coatings:
    • Metal: Galvanized (zinc-coated iron), Tin-coated iron
    • Inorganic: Glass and ceramics
    • Organic: Paint, lacquers, varnishes, polymers
  • Cathodic Protection: Sacrificial anode corrodes instead of the protected metal

Polymers

High molecular weight materials formed by repeating units called monomers.

Historical Development

  1. Mid-19th century: Vulcanization of rubber by Charles Goodyear
  2. Late 19th century: Celluloid, the first artificial plastic
  3. 1909: Bakelite, the first synthetic plastic, discovered by Leo Baekeland
  4. 1979: Development of nylon fibers

Classification by Origin

  • Natural: Starch, cellulose, DNA, RNA, natural fibers (cotton, silk, wool)
  • Artificial: Chemically modified natural polymers (e.g., nitrocellulose, rubber)
  • Synthetic: Plastics, derived from oil and other natural substances

Classification by Physical Properties

  • Thermoplastics: Can be melted and remolded without chemical change
  • Thermosets: Heat-resistant
  • Elastomers: Elastic, quickly recover shape after deformation

Classification by Qualities and Price

  • General Purpose: Cheap, used for everyday objects
  • Engineering Plastics: Maintain properties between 0°C and 100°C
  • Special Plastics: High performance, specific applications (e.g., conductors, photosensitive materials)

Properties of Plastics

  • Low density and lightweight
  • Hardy and strong
  • Easily molded
  • Ductile and malleable
  • Chemical resistant
  • Good heat and electrical insulators
  • Cheap

Manufacture of Plastics

  1. Raw materials (petroleum and natural gas) are extracted
  2. Petrochemical processing creates intermediate materials (ethylene, propylene, etc.)
  3. Polymerization: Monomers link to form polymer chains

Examples of Plastics

  • PET (Polyethylene terephthalate): Flexible, thermoplastic, transparent, used in water bottles
  • HDPE (High-density polyethylene): Flexible, thermoplastic, translucent, used in bleach containers
  • PVC (Polyvinyl chloride): Rigid or flexible, thermoplastic, used in cable sheathing, pipes, vinyl flooring
  • LDPE (Low-density polyethylene): Very flexible, thermoplastic, used in shopping bags, film
  • PP (Polypropylene): Flexible, thermoplastic, used in bumpers, luggage, clothing
  • PS (Polystyrene): Rigid or flexible, thermoplastic, used in yogurt containers, egg cartons

Engineering Plastics

  • Polycarbonate: Impact resistant, heat resistant, optical properties, used in lenses, CDs, DVDs, safety glass
  • Polymethyl methacrylate (PMMA): Competes with polycarbonate, higher resistance and scratch resistance, used in headlights, dentures
  • Teflon: Chemically inert, non-toxic, non-stick, waterproof, withstands extreme temperatures, electrical insulation, used in coating pans, artificial blood vessels
  • Polyamides: Elastic, strong, stretchy fibers, examples include nylon and Kevlar

Other Plastics

  • Rubber: Natural or synthetic, vulcanized to improve properties, used in tires, tubes
  • Polyurethane: Cold-resistant, stable, wear-resistant, flexible foam, used in tubes, clothing
  • Neoprene: Excellent thermal insulation, used in diving suits
  • Silicones: Silicon-based polymers, stable at high temperatures, various applications
  • Sodium Polyacrylate: Absorbs large amounts of water, used in diapers, artificial snow
  • Polyvinyl alcohol (PVA): Water-soluble, used in hospital laundry bags, detergent tablets

Manufacturing Processes for Plastics

  • Injection molding
  • Extrusion
  • Blow molding
  • Vacuum forming

Waste

Definition

Solid, liquid, and gaseous byproducts of production and consumption with no economic value due to lack of appropriate technologies or market demand (OECD).

Trash

Waste material that needs disposal.

The Waste Problem

Technological progress and increased production exceed nature’s absorption capacity.

Waste Management

  • Correct Management: Environmental benefits, increased lifespan of resources
  • Incorrect Management: Environmental damage, reduced quality of life

Solutions

  • Prevention
  • Environmental policies for sustainable development
  • The Three R’s: Reduce, Reuse, Recycle

Waste Classification by Origin

  • Urban/Municipal: Generated in homes
  • Construction and Demolition: Inert waste from construction activities
  • Industrial: Produced by industries, can be similar to urban waste, inert, or hazardous
  • Sanitary/Medical: Generated in medical centers, potentially contaminated with biological substances
  • Mining Tailings: Inert waste from mineral resource extraction
  • Agricultural, Forestry, and Livestock: From farming, agriculture, and forestry activities
  • Radioactive: Wide range, classified by physical condition, radiation type, and half-life