Question

(a)



What is thermit reaction? How it is used in joining railway tracks and cracked


What is thermit reaction? How it is used in joining railway tracks and cracked









parts of machines.













parts of machines.








(b) How do we get stainless steel ?


(b) How do we get stainless steel ?

Answer 1

(a) A thermite reaction is basically iron oxide (rust) reacting with aluminum to produce molten iron. The reaction is initiated by the heat from burning magnesium ribbon which is placed in the iron oxide/aluminum mixture, this is the fuse!

This reaction is highly exothermic and produces molten metal at about 3000°c.

This works because the thermite mixture is aluminum powder and iron oxide (rust) powder. When the mixture is heated, it starts reacting: the aluminum is more reactive than the iron, so it "pinches" the oxygen from the iron to make aluminum oxide and iron.

A balanced equation for the reaction is:-

Fe2O3 + 2Al --> Al2O3 + 2Fe


"how it actually works in railway tracks"

Since the combustion of thermite is an exothermic reaction, it adds heat to its surroundings. The extreme heat literally welds the railway lines back together. Thermite also produces pure molten iron, and aluminum oxide (or something like that). The molten iron fuses with the iron of the rails, welding them together.

(b)   Stainless steel itself is made in an electric arc furnace. Within the furnace, carbon electrodes that are positioned to make contact with scraps of steel blast currents through them. The scraps of steel do not only have to be mixed with chromium. Other elements can be added to enhance the properties of stainless steel, including nickel, nitrogen, and molybdenum. All of this electrode-induced activity takes place in a very high temperature environment.

Upon reaching the critical melting point, the steel scraps and alloys start intermixing until the result is one homogeneous metal fusion. The whole mass is then transferred to an argon oxygen decarbonization (AOD) vessel where deoxygenization occurs. Afterward, casting or forging can be done. Because of its malleable and ductile abilities, the metal can be manipulated into a variety of shapes and forms, or drawn into wires.

As a finishing touch, an electro chemical process can treat the steel into different colors, some of them being gold, bronze, green, blue, and black. Another optional finishing touch is dipping the product in an acid bath, which eliminates any scaling on the stainless steel for a better polished appearance and easy cleanability after usage.


hope it helps!!

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