Silicon Carbide(SiC): Carborundum:

Silicon carbide (SiC) is a compound of silicon and carbon. It is extremely rare on Earth in mineral form (moissanite) and it has semiconductor properties. It has a bluish-black appearance. It has a large number of crystalline forms.

Preparation: When Silica treated with carbon at around 2000℃ to 2500℃ give carbide

Properties:(1) SiC also known as carborundum which is very hard .(2) Silicon carbide is inert and not attack by even HF.
(3) Silicon carbide when treated with NaOH give silicates and carbonate .

(4) Silicon carbide is covalent carbide.

(5) Silicon carbide has a high sublimation temperature and is a good heat conductor. It's expansion with increase in temperature is low. Also, it has high electric field breakdown strength.

(6) Silicon carbide exhibits the phenomenon of polymorphism, and hence has a large number of crystalline forms. Alpha silicon carbide is the most common polymorph and has a hexagonal crystal structure, while Beta Silicon Carbide has zinc blende structure.