Materials Used in Lamp Bulb

Various types of material are used to build a lamp. Insulating materials, conducting materials are the essential parts of a lamp set up. The details of those materials are given below.Glass
  • As it is a transparent material, used as barrier. Light gets various colors depending on the color of the glass.
  • It with stand the pressure of the gas inside the lamp.
  • It is chemically no reactive and used to maintain the lamp as the thematic shield.
The types of the glass vary based on their composition.

Soda Lime Silicate (Soda Glass)

  • It has low melting point
  • It is used in filament lamp.
  • It is used with 67 % SiO2.



Lead Alkali Silicate

  • It is used in the inner portion of the bulb glass.
  • It has higher electrical resistivity.

Borosilicate Glass

  • It used in higher wattage lamp, ex- cinema projector.
  • It has higher temperature with stand capability.
  • Thermal expansion co-efficient is very low.

Alumina silicate Glass

  • It has lower thermal shock capability than borosilicate glass.
  • It is used for low wattage lamp with most refractory convention.

Quartz

  • It is used in tungsten halogen Lamp.
  • It is transparent silica and pure silicon dioxide.
  • It is having only ppm of other metals and OH- group ion.

Sodium Resistant Glass

  • It is used for Na vapor lamp.
  • Powerful reducing property of Na vapor produces rapid blackening. In normal glasses it happens. So small amount of silica or other readily reducing oxide is mixed with it.
  • It has strain throughout life.

Ceramics
  • The modern technology helped to develop to produces poly crystalline metal oxide bodies.
  • Oxide made ceramics transparent or translucent.
  • It includes alumina, magnesia; they are very rare earth oxides.
  • It is pore free structure and permits the visible rays to transmit through it.
  • In the high pressure lamp, they are being used because of transmitting light.
  • In poly crystalline translucent lamp and poly crystalline alumina lamp ceramics are used.
  • Ceramics are used as enclose material in high pressure Na and metal halide Lamp.
Conventional Ceramics Conventional ceramics are of two types, porcelain and steatite.

Porcelain

  • Porcelain is used to make base or the end cap.
  • It has good mechanical strength
  • It possesses good thermal shock resistance and good electrical insulating property.
  • It is having good resistance of attack of moisture.

Steatite

  • It is better than porcelain.
  • It is made of talk, clay, small amount of alkali and alkaline earth oxide.
Metal

Tungsten

  • Its ore is Scheelit(CaWO4), wolframaite (FeMn)WO4
  • By chemical process tungsten is extracted and made it into the wire.
  • Tungsten wire is wound on either on iron or molybdenum mandrel to make coil filament.
  • Impurities (C, O, Fe, N) are strictly controlled to make this coil filament.
  • By mixing AKS (Al, K and Si ) extreme accuracy in coil geometry.
  • Tungsten is mostly used in miniature lamp.
  • This coil is coated with alkaline earth oxide.

Molybdenum

  • Its melting point is 2610oC.
  • It is used to support the filament coil.
  • Its coefficient f expansion matches some categories of glasses.
  • It is used in glass metal shield in many cases.

Nickel

  • It is used in electroplating iron and steel.
  • Small percentage of nickel with iron and steel increases the hardness and elasticity.
  • Nickel steel combination has higher resistance against corrosion.
  • It is used in lead in wire.
  • In bi metallic strip of starter nickel is also used.


Aluminum

  • This metal is non ferrous light weighted and non magnetic material.
  • It is with high corrosion resistance.
  • It has high ductility and malleability.
  • It is easily available.
  • Cheap in price,
  • Aluminum cap is used in suspended lamps.
  • It forms a small thick oxide layer.
  • It does not corrode easily with normal weather.
  • In many cases it is used to make good reflector.

Steel

  • In a structural portion steel is used for fabrication of light equipment.
  • Steel sheet has higher strength and lower cost.
  • Hot rolled, cold rolled and porcelain enameling sheet are the types of steel.
  • Hot rolled steel is used where smooth appearance is desired.
  • Cold rolled is used in case of thinner portion with smooth surface appearance.
  • Porcelain enameling has very less carbon content.

Stainless Steel

  • It includes iron based alloys which contains sufficient chromium.
  • It has higher resistance against corrosion.
  • Its classification is based on presence of chromium from 12% to 30%.
  • It is used in the luminaries, especially outdoor purpose where is a chance of presence of corrosive atmosphere.

Copper

  • In conductor this metal is used extensively.
  • In Bas bar, switch gear copper is also used.
  • It ductile and malleable & strong material.

Non Ferrous Alloys

  • Bronze (Cu + Sn), Brass (Cu + Zn) are non ferrous alloys.
  • They are used in special luminaries.
  • They have attractive color appearance.
  • They are highly resistive against marine water.

Solder

  • It is the alloy of Sn and Pb.
  • It holds on to a surface.
  • It is used at the end of the lamp cap for electrical connection.

Getter Material


  • This material is used to absorb the gas as impurity produced inside the lamp during operation, as the produced gas lower the lamp performance.
  • O2, CO2, CO etc are produced inside the shielded lamp bulb and they are known as getter.
  • Getter material can be in the form of sheet or wire or surface deposit etc.
  • Barium, tantalum, titanium, niobium, zirconium and some of their binary alloys are known as metallic getter.
  • Red phosphor is known as non metallic getter material.
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