Q7Engineering Chemistry
Question
2 marks
What do you understand by annealing of glass and what is its significance?
Answer
Annealing is the controlled slow cooling of glass to relieve internal stresses. It prevents spontaneous cracking and increases durability.
Annealing is a thermal process in which newly formed hot glass is reheated to a specific temperature and then cooled very slowly in a specialized oven called a lehr.
Significance: If glass cools rapidly, the outer surface solidifies faster than the interior, creating severe internal mechanical stresses. Annealing eliminates these stresses, preventing the glass from spontaneously shattering or cracking under minor thermal or mechanical shocks.