Question

The gradual cooling of glass or glass articles is called :
A. Tempering
B. Annealing
C. Quenching
D. Galvanizing

Answer 1

to answer this question the concepts in metallurgy should be known. In metallurgy there are many processes which are used to change the physical properties of the materials. Glass is produced from silica dust by heating followed by cooling after giving a proper shape.

Complete step by step solution:
During the production of glass, silica dust is heated and converted into molten glass. This molten glass cools rapidly after removing it from the mold. Due to this rapid cooling cracking of glass happens. To prevent this another process is used by which gradually cooling of the glass or glass articles can be done. This process is called annealing process.

** So, the correct option is B.**

Additional information:
In the process of annealing a unique furnace which is called lehr is used. It is a long sized oven that has different heating chambers of different temperatures. The glass articles move into all chambers to minimize the stress.

Note: Glass is produced from silica dust by heating followed by cooling after giving a proper shape. Due to the rapid cooling, cracking of glass happens. To prevent this another process is used by which gradually cooling of the glass or glass articles can be done. This process is called annealing process.