Thermit Welding||THERMITE WELDING |TW

 Hello Viewer In this Article you will be able to understand the Basic Principle of Thermit Welding Technology , Which is very important to the Mechanical Students.

Thermit Welding:

Introduction :- 

Thermit Welding is a chemical Welding Process,in which Thermit is use for welding process.Thermit is the mixture of Fine Aluminium powder and Iron Oxide  in the Ratio 1:3

*Ferric oxide (Fe₃O₄ )+ Al (fine Powered  = Thermit Mixture

Barium peroxide is use to ignite the mixture and The process Completes within a fraction of second. Molten metal use to pour inside mould and finally Welding Complets.

Working Principle:

  First of all a vessel in which the chemical Reaction takes place called Crucible Chamber is Cleaned properly.

   A Graphite lining is attached with the Surface of the Crucible Chamber , Thermit ( Mixture of fine Aluminium powder and Iron Oxide)is poured inside and Barium Peroxide (Low melting point)is also attach for the ignition purpose.

The ignition Method May be:-

• By Using Fire Crackers ( Fuljhuri)
• Magnesium Ribbon
• Red hot Metal
• Matchstick
• Gas lighter,etc

The Chemical Reaction takes place in Thermit Welding is

3Fe₃O₄ (s) + 8Al (s) →4Al₂O₃(L ,Slag) + 9Fe(L ,Pure Iron) + Heat (3000°c) Exothermic Reaction takes place

As the result of chemical Reaction about 3000°C heat generated but ,Preheating of Mixture done upto about 1300°c is essential to Start the reaction 

 

 Finally the taping pin is allow to open and allow fall in the Mould which is already prepared.

 

 The molted metal comes in the mould through the Runner ,and to that part which has to be joined by vapourising the Vax.

 

 Which is place on the joining part along with fine refactoring Sand in the Mould.

Since the Density of Aluminium (L) is low as compared to that of Iron (L) ,so the Aluminium Slag comes upper and The Pure iron Settled Down.

 The Riser is also provided to Excess liquid flow up above the Part or Shape to make sure the mould is completely full with molten Metal

Application :

• To weld railway track(line)

• Steel pipes
• Steel wires
• Large cast and forge parts

Advantages

• Fast welding process
• No need to use high Electricity
• It can be weld on the site where other welding process is comparatively difficult
• Negligible heat Affected Zone 
• Difference Between Thermal temperature of base metal and coefficient of thermal of the joint is less so no major effect on the properties.

Disadvantages :

• Thermit Mixture is costly
• High temperature generates in a fraction of second so it need experience welder

Tags:- Thermit Welding Technology, THERMIT WELDING