Overview
This lecture explains how glass is made, the raw materials involved, the manufacturing process, and how glass properties can be modified for different uses.
What Glass Is Made Of
- Glass is primarily made by melting sand, which is mainly composed of silicon dioxide (silica).
- The sand used is rich in quartz crystals, each made of silicon dioxide molecules.
Glass Manufacturing Process
- Sand must be heated to about 1700°C (3090°F) to melt and begin forming glass.
- When heated, silica loses its crystalline structure and forms an amorphous solid—a state between liquid and solid.
- Amorphous solids have some order like a solid but molecular randomness like a liquid.
Types and Properties of Glass
- Glass can have different properties depending on ingredients added to the sand.
- Coloring agents can be added to change glass color.
- Most common glass is soda-lime glass, made from sand, soda ash (sodium carbonate), and limestone (calcium carbonate).
- Soda ash lowers the melting point of the glass, making manufacturing more energy-efficient.
- Limestone is added to improve the chemical durability of glass, preventing it from dissolving in liquids.
Strengthening and Shaping Glass
- Glass can be strengthened by thermal tempering (rapid heating and cooling).
- Chemical strengthening (such as ion exchange) makes the surface of glass tougher.
- Glass can be molded into different shapes for a variety of applications.
Key Terms & Definitions
- Silica (Silicon dioxide) — Main ingredient in sand used to make glass.
- Amorphous solid — A state of matter with a structure between liquid and solid, characteristic of glass.
- Soda-lime glass — The most common type of glass, made from sand, soda ash, and limestone.
- Soda ash (Sodium carbonate) — Added to sand to lower its melting point.
- Limestone (Calcium carbonate) — Added to increase the chemical durability of glass.
- Ion exchange — A chemical process used to strengthen glass.
Action Items / Next Steps
- Review the definitions of key glass ingredients and processes.
- Research different uses and strengthening methods of glass for various applications.