Metal is an element, compound or alloy that is a good conductor of both electricity and heat

Metal is an element, compound or alloy that is a good conductor of both electricity and heat

• Metal is an element, compound or alloy that is a good conductor of both electricity and heat

• Metal crystal structure and specific metal properties are determined by metallic bonding – force, holding together the atoms of a metal

Ability of the valence free electrons to travel throughout the solid explains both the high electrical conductivity and thermal conductivity of metals.

• Ability of the valence free electrons to travel throughout the solid explains both the high electrical conductivity and thermal conductivity of metals.

Other specific metal features are: luster or shine of their surface (when polished), their malleability (ability to be hammered) and ductility (ability to be drawn).

• Other specific metal features are: luster or shine of their surface (when polished), their malleability (ability to be hammered) and ductility (ability to be drawn).

• These properties are also associated with the metallic bonding and presence of free electrons in the crystal lattice.

Iron

• Iron

• Pig iron
• Cast iron
• white cast iron
• grey cast iron
• Wrought iron

Iron (Fe) – atomic number 26

• Iron (Fe) – atomic number 26

• most widely used of all metals as base metal in steel and cast iron

• Pig iron - the intermediate product of smelting iron ore with a high-carbon fuel such as coke, usually with limestone as a flux

Cast iron – is derived from pig iron

• Cast iron – is derived from pig iron

• White cast iron is named after its white surface when fractured, due to its carbide impurities which allow cracks to pass straight through.
• Grey cast iron is named after its grey fractured surface, which occurs because the graphitic flakes deflect a passing crack and initiate countless new cracks as the material breaks.

Wrought iron - iron alloy with a very low carbon content, in comparison to steel, and has fibrous inclusions (slag)

• Wrought iron - iron alloy with a very low carbon content, in comparison to steel, and has fibrous inclusions (slag)
• tough, malleable, ductile and easily welded

Steel

• Steel

• Cast steel
• Stainless steel
• High-speed steel

Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by mass

• Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by mass

• Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, molybdenum, tungsten, etc.

Stainless steel (inox steel) is a steel alloy with a minimum of 10.5 or 11% chromium content by mass.

• Stainless steel (inox steel) is a steel alloy with a minimum of 10.5 or 11% chromium content by mass.

• It does not corrode, rust, or stain with water as ordinary steel does.

High speed steel is commonly used in tool bits and cutting tools.

• High speed steel is commonly used in tool bits and cutting tools.

• It can withstand higher temperatures without losing its hardness. This property allows HSS to cut faster than high carbon steel, hence the name high speed steel.

1. Preparation of iron ore

• 1. Preparation of iron ore

• Crushing
• Screening
• Roasting with limestone and coke in blast furnace
• 2. Pig iron = crude iron
• Main impurities: - carbon, silicon, manganese, sulphur, phosphorus

4. Cast iron – obtained by remelting pig

• 4. Cast iron – obtained by remelting pig
• 5. Steel alloys - to reach higher tensile strength, yield point, endurance limit, impact strength

A blast furnace is a type of metallurgical furnace used for smelting industrial metals, generally iron.

• A blast furnace is a type of metallurgical furnace used for smelting industrial metals, generally iron.

• In a blast furnace, fuel, ore and limestone as flux are continuously supplied through the top of the furnace, while air (sometimes with oxygen enrichment) is blown into the bottom of the chamber, so that chemical reactions take place throughout the furnace as the material moves downward.

The end products are usually molten metal and slag phases tapped from the bottom, and flue gases exiting from the top of the furnace.

• The end products are usually molten metal and slag phases tapped from the bottom, and flue gases exiting from the top of the furnace.

Copper

• Copper

• Aluminium

• Zinc

• Tin

• Lead

Copper – Latin cuprum (Cu) – ranks next to iron in importance and wide range of application

• Copper – Latin cuprum (Cu) – ranks next to iron in importance and wide range of application

• good heat and electrical conductivity

• resistance to corrosion

• Alloys: brass, bronze, cupro- nickel (copper nickel) alloys

Aluminium (BrE) or aluminum (AmE) – Al, atomic number 13

• Aluminium (BrE) or aluminum (AmE) – Al, atomic number 13

• whitish with bluish cast

• the third most abundant element (after oxygen and silicon), and the most abundant metal in the Earth’s crust

low density and ability to resist corrosion; good conductivity

• low density and ability to resist corrosion; good conductivity

• structural components made from aluminium and its alloys are vital to the aerospace industry and are important in other areas of transportation and structural materials

Zinc (Zn), atomic number 30

• Zinc (Zn), atomic number 30

• bluish white

• corrosion resistant in air due to a thin oxide film forming on its surface

• used as a coating for protecting steel - galvanisation (or galvanisation) is the process of applying a protective zinc coating to steel or iron, in order to prevent rusting

Tin – Latin stannum (Sn), atomic number 50

• Tin – Latin stannum (Sn), atomic number 50

• white, lustrous, soft, malleable, ductile, resistant to corrosion

• used as coating for steel and sheet iron

• white metal – tin based alloy with amounts of lead, copper and antimony – lining material

Lead – Latin plumbum (Pb), atomic number 82

• Lead – Latin plumbum (Pb), atomic number 82

• metallic lead has a bluish-white colour after being freshly cut, but it soon tarnishes to a dull grayish color when exposed to air

• has a shiny chrome-silver luster when it is melted into a liquid

soft, malleable, has little ductility

• soft, malleable, has little ductility

• usage: plates for storage batteries, covering for electrical cables

Non-Metals are poor conductors of heat and electricity when compared to metals as they gain or share valence electrons easily (as opposed to metals which lose their valence electrons easily)

• Non-Metals are poor conductors of heat and electricity when compared to metals as they gain or share valence electrons easily (as opposed to metals which lose their valence electrons easily)

• usually have lower densities than metals;

• they have significantly lower melting points and boiling points than metals

• brittle, non-ductile, dull (do not posses metallic luster)

Plastics

• Plastics

• Thermosetting polymer

• Epoxy resin

• Thermoplastic

• Rubber

Plastics:

• Plastics:

• immune to corrosion

• insulator

• unsuitable for higher temperatures

• to improve their properties additives are given

A thermosetting plastic, also known as a thermoset, is polymer material that irreversibly cures. The cure may be done through heat (generally above 200 °C), through a chemical reaction (two-part epoxy, for example).

• A thermosetting plastic, also known as a thermoset, is polymer material that irreversibly cures. The cure may be done through heat (generally above 200 °C), through a chemical reaction (two-part epoxy, for example).

Thermoset materials are usually liquid or malleable prior to curing and designed to be molded into their final form, or used as adhesives. Others are solids like that of the molding compound used in semiconductors and integrated circuits (IC).

• Thermoset materials are usually liquid or malleable prior to curing and designed to be molded into their final form, or used as adhesives. Others are solids like that of the molding compound used in semiconductors and integrated circuits (IC).

• Once hardened, a thermoset resin cannot be reheated and melted back to a liquid form.

Epoxy resin – thermosetting plastic

• Epoxy resin – thermosetting plastic

• usage: chocking materials

Thermoplastic, also known as a thermosoftening plastic is a polymer that turns to a liquid when heated and freezes to a very glassy state when cooled sufficiently.

• Thermoplastic, also known as a thermosoftening plastic is a polymer that turns to a liquid when heated and freezes to a very glassy state when cooled sufficiently.

• Thermoplastic polymers differ from thermosetting polymers in that they can be remelted and remoulded.

Rubber

• Rubber

• rough, elastic material

• unaffected by water

• attacked by oil and steam

• usage: gaskets, flexible couplings, vibration mount