Magnesium oxide (chemical formula MgO) is a high-melting-point, non-toxic, white powdered inorganic compound. As an alkaline oxide, it possesses excellent fire resistance, chemical stability, and adsorption properties. It is widely used in industrial refractory materials, pharmaceutical antacids, environmental pollution control, food additives, and new energy materials.

Magnesium oxide used in glass fiber production must possess specific characteristics that are compatible with the glass melting process and fiber performance requirements:

• High purity and low impurities: Typically, the magnesium oxide content is required to be ≥95%, with strict control of impurities such as silicon, iron, calcium, and chlorine (e.g., iron ≤ 0.1%, calcium ≤ 0.5%). This prevents impurities from forming bubbles or stones in the molten glass, ensuring defect-free finished glass fibers.
• Appropriate activity and particle size: Magnesium oxide powders with medium-to-low activity (activity value 40-60s) and fine particle size (average particle size 1-5μm) allow for uniform mixing with glass raw materials and rapid dissolution during high-temperature melting.
• Stable chemical properties: The powder must be heat-resistant (above 2800°C) with non-decomposition and non-volatilization in glass melting environments (1500-1600°C). It must stably react with elements such as silicon and aluminum to form a dense glass structure.
• Low hygroscopicity and good fluidity: The finished product must be dried to a moisture content of ≤0.5% to prevent moisture absorption and agglomeration. The powder must exhibit good fluidity for continuous feeding and precise metering requirements.

Magnesium oxide plays a key functional role in glass fiber production with multiple advantages:

• Performance enhancement: Improves high-temperature resistance, tensile strength, impact resistance, and corrosion resistance of glass fibers.
• Production optimization: Reduces glass melt viscosity, improves fluidity, and facilitates smooth drawing and forming processes.
• Cost-effective: Wide availability of raw materials and low cost while maintaining performance standards.
• Environmental benefits: Non-toxic and non-volatile properties meet green production requirements.
• Composite material improvement: Enhances interfacial bonding in glass fiber reinforced composites, improving structural stability and mechanical properties.