English to Polish Tech/Engineering Materials (Plastics, Ceramics, etc.) glass-ceramics

Kontekstu trochę jest, ale i tak nie wiem...
The composition is formed by batching a Na2O concentration into the bulk glass.
The crack then propagates through the compressive stress layer into the bulk of the glass.
P2O5 can be used to achieve bulk nucleation.
Boron levels must be controlled to maintain chemical durability and mechanical strength of the bulk glass.
Stress optical coefficient is measured by a bulk cylinder method.