What material is glass made of? It turns out that there is a lot of exquisiteness, and the article explains the production materials and processes of glass!

As a material widely used in construction, home, industry, and technology, glass is favored for its transparency, durability, and versatility. The glass production process involves a variety of raw materials and complex processes, and the choice of ingredients and formulations directly affects the performance and use of glass.

1. The main raw materials of glass

The production of glass is based on natural minerals and chemicals, and the main raw materials include silica sand, sodium carbonate, calcium carbonate, etc. These materials are transformed into glass products with specific properties through high-temperature melting and molding processes. Here are the most commonly used raw materials in glassmaking and their roles:

1. Silica sand (silica, SiO₂)

• Function: Silica sand is the main component of glass, accounting for 70%-75% of glass raw materials. Silica is a network former that forms the glass skeleton, providing the structural strength and transparency of the glass.

• Characteristics: Silica sand has a high melting point (about 1700°C) and needs to be combined with other materials to reduce the melting temperature. High-quality silica sand needs to be of high purity and low content of impurities (such as iron and aluminum) to ensure the transparency and color of the glass.

• Source: Silica sand mainly comes from natural quartz placers, distributed in Shandong, Jiangsu, Guangdong and other places.

2. Sodium carbonate (soda ash, Na₂CO₃)

• Function: Sodium carbonate acts as a flux to reduce the melting point of silica (from 1700°C to about 1400°C), making the glass easier to shape and saving energy.

• Properties: Soda ash decomposes at high temperatures, releases carbon dioxide, reacts with silica sand to form sodium silicate, and improves the fluidity of glass.

• Source: Sodium carbonate is usually produced through the chemical industry, such as the Solvay method (ammonia-alkali method), our country is one of the major producers of soda ash in the world.

3. Calcium carbonate (limestone, CaCO₃)

• Function: Calcium carbonate acts as a stabilizer, enhancing the chemical stability and mechanical strength of the glass, preventing it from dissolving or aging in humid environments.

• Properties: At high temperatures, calcium carbonate decomposes into calcium oxide (CaO) and carbon dioxide, and calcium oxide reacts with silica to form a stable calcium silicate structure.

• Source: Limestone is rich in reserves in our country, mainly produced in Guangxi, Yunnan and other places.

4. Other auxiliary materials

• Alumina (Al₂O₃): Improves the hardness and heat resistance of glass, often achieved by adding feldspar or alumina powder

• Magnesium Oxide (MgO): Enhances the corrosion resistance of glass, often used as a source

• Boron oxide (B₂O₃): Used to make heat-resistant glass (such as borosilicate glass) to reduce the coefficient of thermal expansion, often used in laboratoryware

• Colorants and clarifiers: such as iron oxide (Fe₂O₃) for green glass, cobalt oxide (CoO) for blue glass; sodium sulfate (Na₂SO₄) or nitrate as clarifier to remove air bubbles

2. Differences in glass types and material formulas

1. Ordinary soda-lime glass

• Composition: about 70% silica, 15% sodium oxide, 10% calcium oxide and other small amounts of oxides

• Characteristics: low cost, high transparency, easy processing, widely used in architectural windows, bottles and cans, etc

• Application: Soda-lime glass accounts for more than 70% of the glass market and is commonly found in residential windows and daily glass products

2. Borosilicate glass

• Composition: about 80% silica, 13% boron oxide, 4% sodium oxide, 2% alumina.

• Characteristics: High temperature resistance, chemical corrosion resistance, low coefficient of thermal expansion, suitable for high temperature environment.

• Applications: Labware (e.g., test tubes, beakers), heat-resistant cookware (e.g., Pyrex glass pans).

3. Lead crystal glass

• Composition: Add 20%-30% lead oxide (PbO) to replace part of the calcium oxide and sodium oxide.

• Characteristics: High refractive index, crystal clear, suitable for making high-end decorations, but due to lead, attention should be paid to environmental protection issues.

• Application: crystal glassware, handicrafts.

4. Tempered glass and laminated glass

• Composition: Based on soda-lime glass, strength is enhanced by physical or chemical treatments.

• Characteristics: Tempered glass increases surface stress through rapid cooling, while laminated glass adds PVB (polyvinyl butyral) film between the glass.

• Application: Automotive windshield, building curtain wall.

3. Glass production process

1. Raw material ingredients

• Process: According to the type of glass, accurately proportion silica sand, soda ash, limestone and other raw materials, and mix evenly. Impurities such as iron need to be strictly controlled to ensure glass quality.

• Equipment: batching machine, electronic scale for precise weighing and mixing.

2. Melting

• Process: The prepared raw materials are sent to the glass kiln and melted into liquid glass at a high temperature of 1400°C-1600°C. Clarifiers, such as sodium sulfate, remove air bubbles and ensure uniform glass.

• Equipment: Pool kiln or crucible kiln, modern factories mostly use continuous pool kilns to improve efficiency.

3. Molding

• Process: The molten glass is shaped into the desired shape through different processes. Common methods include:

(1) Float process: Liquid glass floats on molten tin to form a flat glass plate, which is widely used in architectural glass.

(2) Blowing process: used to make glass bottles or handicrafts, traditional manual or mechanical blowing.

(3) Drawing/Calendering: Used to produce glass tubes or textured glass.

• Equipment: float production line, blow molding machine, calender.

4. Annealing

• Process: The formed glass needs to be slowly cooled (annealed) to eliminate internal stresses and prevent cracking. The annealing time depends on the glass thickness and type and usually lasts several hours.

• Equipment: annealing kiln to control the cooling rate.

5. Post-processing

• Process: Includes cutting, sanding, tempering, coating, and other processes to improve the strength, aesthetics, or functionality of the glass. For example, coated glass can reflect infrared rays, which is energy-saving and environmentally friendly.

• Equipment: cutting machine, tempering furnace, coating equipment.

4. Characteristics and application scenarios of glass materials

1. Characteristics

• Transparency: The high light transmission of glass makes it widely used in windows and optics.

• Chemical stability: resistant to acid and alkali corrosion, suitable for storing food or chemical reagents.

• Plasticity: By adjusting the formulation and process, glass can be made in a variety of shapes and properties.

• Eco-friendly: Glass is 100% recyclable and meets sustainability requirements.

2. Application scenarios

• Construction field: soda-lime glass is used for windows, curtain walls; Tempered glass is used in the facades of high-rise buildings.

• Household items: glasses, tableware, decorations, focusing on aesthetics and practicality.

• Industry and technology: Borosilicate glass is used in laboratory equipment, optical glass is used in lenses, and photovoltaic glass is used in solar panels.

• Automotive industry: Laminated glass and tempered glass are used in car windows to improve safety.

5. Selection and purchase suggestions for glass materials

1. Choose according to the use

• Home decoration: Choose soda-lime glass or lead-crystal glass with high transparency and smooth surfaces.

• High-Temperature Resistance Needs: Prefer borosilicate glass, such as heat-resistant teapots or baking trays.

• Safety Needs: Tempered glass or laminated glass is suitable for doors, windows, or public spaces.

• Energy saving and environmental protection: Choose low-E coated glass to reduce heat transfer.

2. Purchase precautions

• Check the quality: The surface of high-quality glass is free of bubbles, scratches, and has flat edges.

• Brand Selection: Well-known brands such as Fuyao Glass, Xinyi Glass, and Taiwan Glass Group provide high-quality products.

• Environmental Certification: Choose glass products that have passed ISO 14001 or China Environmental Label certification.

• Thickness and specifications: Choose the appropriate thickness according to the application, such as architectural glass is usually 4-12 mm.

When purchasing glass products, you should choose the right material based on the purpose, performance and environmental protection requirements, while paying attention to brand reputation and quality certification. With the advancement of technology and the deepening of environmental protection concepts, glass materials will usher in greater breakthroughs in functionality and sustainability, bringing more possibilities to life and industry.