tecnología

    Three-age system
  • The Stone Age/Edad de Piedra
    • Paleolithic/Paleolítico
    • Mesolithic/Mesolítico
    • Neolithic/Neolítico
  • The Bronze Age/Edad de Bronce
    • Copper Age(Chalcolithic)/Edad de Cobre(Calcolítico)
    • Bronze Age/Edad de Bronce
  • The Iron Age/Edad de Hierro

States of the matter
Solid
Liquid
Gas
Plasmafree charged particles such as ions and electrons.
Bose-Einstein condensateSuper-cooled atoms that bunch together
electron-degenerate matterfound inside a white dwarf star
neutron-degenerate matterfound inside a neutron star

Change in states of the matter
Gasdeposition or reverse sublimation or resublimation→
←sublimation
Solid
Gasionization→
←recombination or deionization
Plasma
liquidVaporization:evaporation and boiling→
←condensation
Gas
SolidMelting or liquefaction or fusion→
←Freezing or solidification
Liquid

Structure of solids
CrystallineRegular repeating three-dimensional highly ordered structure
Sharp, well-defined melting points
To form a crystal: long periods of time, no impurities, components fit together
examples: gems, snowflakes, diamonds, table salt, silicon single crystals for the electronics industry, certain types of fibers, ice crystals, superalloy for turbojet engines
    Unit cell
  • Cubic
    • simple cubic
    • body-centered cubic (bcc):δ-Fe, α-Fe
    • face-centered cubic (fcc): γ-Fe, Au
  • Tetragonal
  • Orthorhombic
  • Monoclinic
  • Hexagonal
  • Rhombohedral
  • Triclinic
Poly-crystallinelarge number of single crystals held together by thin layers of amorphous solid
examples:almost all metals, ceramics, ice, rocks
AmorphousNo particular order
Soften slowly over a wide temperature range
examples: glass, wax, many plastics

raw materials→semi-manufactured products or goods→manufactured products or goods

    materials classification by origin
  • Raw materials/materias primas
    • vegetable/vegetal
      • Wood,cotton,cork,latex
    • animal/animal
      • Silk,wool,leather
    • mineral/mineral
      • non-metallic/no metálico
        • Limestone,Silica,Gypsum
      • metallic/metálico
        • Ferrous/ferroso
          • Iron,steel,Cast Iron
        • Non-ferrous/no ferroso
          • Copper,Aluminium,Titanium,Magnesium,Gold
  • Processed materials or manufactured materials(man-made or man-made produced by chemical synthesis)
    • Artificial/artificial
      • celluloses
    • Synthetic/sintético
      • many plastics:polyester,nylon
  • Recycled materials/Materiales reciclados
    • some paper and plastic
    materials
  • wood/madera
    • paper/papel
    • card/cartulina
    • cardboard/cartón
    • cork/corcho
  • metals/metales
  • polymers or plastics/polímeros o plásticos
  • fabrics or textile fibres/fibras textiles
  • stone,ceramics and glass/Petreos,cerámicos y vidrios
  • Leather/cuero
  • composite materials:composites/Composites:
    • polymer-matrix composite(PMC)or fiber reinforced plastics(FRP)
  • shape memory alloys(SMA)/Aleaciones con memoria
  • new materials:
    • glass fibre/Fibra de vidrio
    • carbon fibre/Fibra de carbono
    • Graphene/Grafeno
    • Fullerene:carbon nanotubes,buckminsterfullerene/Fulerenos

Properties of materials
Physical Properties
DensityThis is the relationship between the mass and the volume
A dense material is said to be heavy
density=mass/volume. SI unit kg/m3. cgs unit g/cm3
Most wood has a density of between 0.3-0.9 g/cm3 -it is less dense than water, so it floats-
Densities of various material (g/cm3)
Water
  • Ice: 0.916 (<0°C)
  • Water: 1 (4°C)
Wood
  • Balsa: 0.16
  • Pine: 0.373
  • Cypress: 0.51
  • Oak: 0.71
Plastics
  • PP: 0.86
  • LDPE: 0.88
  • HDPE: 0.96
  • PS: 1.05
  • PETE: 1.31
  • PVC: 1.4
Metals
  • Magnesium: 1.74
  • Beryllium: 1.85
  • Aluminium: 2.7
  • Titanium: 4.54
  • Zinc: 7
  • Iron: 7.87
  • Copper: 8.94
  • Silver: 10.5
  • Lead: 11.34
  • Gold: 19.32
  • Osmium: 22.57
Ceramics
  • Cermet: 6
  • Alumina: 3.8
  • Steatite:2.6
  • Porcelain: 2.3
Freezing point/Punto de congelaciónThe temperature at which a liquid becomes a solid
Melting point/Punto de fusiónThe temperature at which the solid becomes a liquid
Low and hight melting point
Melting Points (°C)
Aluminium660.3Copper1085Nickel1455
Gold1064Iron1538Tin231.9
Lead327.5Mercury-38.8Zinc419.5
Tungsten3400Magnesium650Silver961
Boiling point/Punto de ebulliciónThe temperature at which a liquid becomes a gas (changes into a vapor)
Temperature at which the vapor pressure is large enough that bubbles form inside the body of the liquid
Temperature remains constant until all the liquid has been converted to a gas
Boiling point of water is 100°C at 1 atm(atmosphere)=760 mmHg
Thermal properties
Thermal conductivityThe ability of a material to conduct heat
Heat always travels from a warmer area to a colder area
Hot →warm→cool→cold
    Thermal insulators:
  • If the object is hot keep it warm.
  • If the object is cold keep it cool.
  • Wood, plastic and ceramic materials
  • A saucepan's handle.
    Thermal conductors:
  • Metals
Thermal conductivity (W/(m °K)
Zinc116Steel, C 1%43Iron80
Cast iron58Bronze110Gold310
Brass109Aluminum205Copper401
Silver429Titanium22Nickel91
PP0.1-0.22Urethane foam0.021Polyester0.05
Nylon 660.25Neoprene0.05LDPE0.33
Sheep wool0.039Cotton0.04Acrylic0.2
Timber, white pine0.15Wood, oak0.17Cork0.07
Paper0.05Vacuum0Wax0.084
Porcelain1.5Sand, dry0.15-0.25Soil, clay1.1
Water0.58Snow (temp<0°C)0.05-0.25Ice (0°C)2.18
Rock, solid3-7Glass, window0.96Air0.024
Thermal Expansion/Dilatación térmicaThe dimensions (length, area, and volume) of substances change when they are heated
Most materials expand when heated and contract as they cool down
Large structures such as railways tracks, bridges, pipes, pavement (sidewalk, footpath, footway) and buildings need expansion joints to absorb the heat-induced expansion and contraction (and to absorb vibration or to allow movement due to ground settlement or earthquakes)
It is larger for liquids than solids
For common materials like many metals and compounds, the thermal expansion coefficient is inversely proportional to the melting point
Thermal expansion linear coefficent at 20°C (10-6°K-1
Aluminium23.1Brass19Copper17
Gold14Iron11.8Silver18
Steel11-13Concrete12Glass8.5
Mercury61Oak54PP150
PVC52Water69Polyester123.5
HDPE108Pyrex, glass4
Thermal contraction
Fusibility/FusibilidadChange from solid to liquid when their temperature is increased(Technological property)
Weldability/SoldabilidadSome materials can be used to weld two pieces of the same or different materials together(Technological property)Steels and plastic
Chemical properties
Oxidation/OxidaciónIt is a chemical reaction of metals or no-metals with oxygen in the air
    Redox
    It is a chemical reaction with electron transfer processes by a molecule, atom, or ion
  • Reduction: the gain of electrons
  • Oxidation: the loss of electrons
A reduction-reaction always comes together
Oxygen does not have to be present in a reaction
Metals in general create a surface layer of oxide
rust is the reddish-brown substance produced by oxidation
Corrosion/CorrosiónIt is a similar process to oxidation
It is a galvanic reaction (electrochemical reaction) with a loss of electrons (like oxidation) but in a different medium (like Humidity in the atmosphere, Sea water, different metal...)
The material that lose more electrons has more erosion.
    Methods for preventing corrosion and oxidation
  • Protecting the metal surface
    • Paints (Brush, Roller, Air spray, Electrostatic airless spray) for static metal surfaces
    • Lubricants to moving metal parts (ensure smooth, easy motion)
    • Galvanization (hot-dip or electroplating) is the process of coating (covering) iron and steel with a layer of zinc
    • Tinplate is iron and steel coating with a thin layer of tin
  • Cathodic protection (sacrificial anodes: Zinc, Aluminum and magnesium)
  • Impressed current (stop electrons to flow out of the metal)
  • Anodizing is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts (to protect aluminium alloys, titanium, zinc, magnesium, niobium)
  • Making alloys:
    • Stainless steel:Steel is mixed with a certain amount of chromium and nickel
Mechanical Properties
Elasticity/ElasticidadAbility of materials to regain(to return or to recover) their original shape after having been subjected to forces.
Plastic and wood
Spring is elastic due to its shape
Plasticity/PlasticidadThe ability of a material to undergo permanent deformation without breaking
Clay,plasticine-Play-Doh. Metal
Malleability/MaleabilidadAbility of materials to be spread into sheets or films.(Technological property)
Malleable
Gold
Ductility/DuctilidadAbility of materials to be formed(stretched) into filaments or wires.(Technological property)
Ductile
Nylon,copper
Hardness/DurezaResistance of materials to being scratched or penetrated by another material
In the past:Mohs scale(it was based on ten minerals with hardness rating from 1 -Talc- to 10 -Diamond-)
At present it is tested by using a durometer which drives a ball or a cone
Toughness/TenacidadResistance to breaking when hit(strike) by something
Metal
Brittleness/Fragilidadwhen a material breaks easily
Glass
Stiffness or rigidity/RigidezResistance offered by an elastic body to deformation in response to an applied force
Flexibility/FlexibilidadThe more flexible an object is, the less stiff it is
Mechanical resistance
Mechanical strengthMeasure of how good a material is to withstand forces without breaking or deforming
tensile strength(tension)/resistencia a la tracciónResistance to stretching (A pulling force)
compressive strength(compression)/resistencia a la compresiónResistance to being crushed ( A pushing force)
flexural strength(Bending)/FlexiónResistance to bending
torsional strength-Torque strength-(Torsion)/torsiónResistance to twisting force
shear strength/resistencia a cizalladura o corteAbility to resist forces that can cause to slide against itself (cutting)
Fatigue strengthAmplitude(or range) of cyclic stress that can be applied to the material without causing fatigue failure
Ecological properties or Environmental properties
Recyclable materialspaper, glass, metal and plastic polymers
Down-cycling:A recycled product with loss of quality (paper, plastic)
    Recycling of plastics
    • Chemical recycling
    • degrade the plastics waste into their monomers or other basic chemicals
      For polymerisation into new plastics, other chemicals or alternative fuel
      Thermosets can be reprocessed in this way
    • Mechanical recycling (Physical R.)
    • by grinding, washing, separating, drying, re-granulating and compounding
      to be converted into new plastics
      Only thermoplastic are of interest
      examples: PP, PE-LD, PET
    • Energetic recycling
    • Incineration
    • Gasification
    • Pyrolysis
    • Thermal depolymerization
      Heating value(MJ/Kg)
      Natural gas48Oil43Coal28
      Paper/Wood16PE41.8PP30.9
      PVC13.69PS38.97PET21.81
    Feedstock recycling
  • For difficult to recycle plastics that allows them to be turned into valuable chemical building blocks
  • Gasification and pyrolysis: synthesis gas (syngas) and liquid and semi-liquid products
  • Depolimerization: monomers for virgin plastics
    the law of the three R's of the enviorement:
  • Reduce
  • Reuse
  • Recycle
Toxic materials
Biodegradable materialsnon-biodegradable materials:The process of decomposition and absorption can take hundreds of years
Renewable raw materialswool,cotton and wood
Non-renewable raw materials:coal,oil and minerals
Sensory properties
Optical properties
Colour
TransparencyOther objects can clearly be seen through these materials. Transparent.
Examples: Glass and some plastics
TranslucencyIt allows light to pass through them, but diffusing it
examples: some types of glass,tissue paper and plastic
OpacityThe opposite property of translucency
examples: Wood and metals
Others properties
Electrical conductivityThe ability of a material to transmit electricity
It allows electricity(electric current)to flow(to pass)through it
Good and bad conductors of electricity
Electrical Conductors,insulators and semiconductors

Electrical conductors:Metal. Salt water. graphite(a form of carbon-non-metal-)
pins in a plug.
Acoustic propertiesAcoustic insulators
Glass,fibre,cork and plastics
Magnetic propertiesMagnetism
Some metals attract other metallic materials.iron
Acoustic conductivityThe capacity of materials to transmit sound.
PorositySome materials contain tiny holes called pores.
Wood, some stone and ceramic
PermeabilitySome materials allow water or other liquids to pass through them
earthenware jug
ImpermeabilityDoes not allow water or liquid to pass through it
Combustion. Burns easily
Hygroscopicity
Resistant to Moisture
Humidity
Rotting and insect attack
Cleavabilitythe quality of resistance to other objects such as nails,screws,tools.
Physical stateAll metals are solids at room temperature except mercury and gallium
Inexpensive,less expensive
Not affected by parasites
Not deform easily
Ease of creation and transformation
Anisotropyenables them to show greater or lesser resistance depending on the direction of the force that they have to support