1. Advantages of calcined brown corundum
1. High hardness and wear resistance
Advantages: The hardness of brown corundum after calcination can reach Mohs 9.0-9.2, which is close to diamond, and has excellent wear resistance. It is suitable for manufacturing high-precision molds, grinding wheels or grinding tools.
Application scenarios: Suitable for molds and abrasives for processing hard materials (such as metals, ceramics, and glass).
2. Excellent thermal stability
Advantages: Low thermal expansion coefficient after calcination (about 7.0×10⁻⁶/℃), not easy to deform at high temperature, heat resistance can reach more than 1800℃, suitable for high-temperature molding molds.
Application scenarios: hot pressing molds, casting molds or high-temperature sintering molds.
3. Chemical inertness and corrosion resistance
Advantages: High Al₂O₃ content (≥95%), strong corrosion resistance to acids, alkalis, and molten metals, suitable for corrosive environments.
Application scenarios: chemical molds, electroplating tools or molten metal casting molds.
4. Particle uniformity and processing performance
Advantages: After calcination, the particles have regular shape and uniform particle size, which are easy to combine with binders (resins, ceramics, etc.) to improve the surface finish of the mold.
Application scenarios: precision injection molds, optical glass molding molds.
5. Economical
Advantages: Although the unit price is high, it has a long life and low maintenance cost, and is more cost-effective for long-term use.
2. Disadvantages of calcined brown corundum
1. High brittleness
Disadvantages: High hardness but low toughness, poor impact resistance, and easy to crack under severe impact or stress concentration.
Limitations: Not suitable for molds with high impact loads (such as forging molds).
2. Difficult processing
Disadvantages: High hardness requires the use of diamond tools for cutting, forming and polishing, which has high processing costs and low efficiency.
Limitations: The manufacturing cycle of complex shape molds is long and the process requirements are high.
3. High cost
Disadvantages: The calcination process is complex, the energy consumption is high, and the cost of raw materials (high-purity bauxite) is high.
Comparison: Ordinary brown corundum (uncalcined) is cheaper, but has poorer performance.
4. Sensitive to impurities
Disadvantages: If the calcination process is not properly controlled (such as uneven temperature), residual impurities (Fe₂O₃, SiO₂) may affect the performance.
Limitations: The raw materials and calcination process must be strictly controlled, otherwise cracks or strength reduction are likely to occur.
5. Poor conductivity
Disadvantages: Al₂O₃ is an insulator and cannot be used in special molds that require electrical or thermal conductivity (such as some electronic component molding molds).
Alternatives: Silicon carbide or metal-based composite materials should be used in such scenarios.
3. Comparison with other materials
Material Advantages Disadvantages
White corundum Higher purity, slightly better hardness Lower toughness, higher cost
Silicon carbide Better thermal conductivity and thermal shock resistance Higher price, conductivity may not be applicable
Uncalcined brown corundum Low cost, easy processing Poor wear resistance and high temperature resistance
4. Summary
Applicable scenarios:
Calcined brown corundum is suitable for precision molds (such as glass molds, ceramic molds, precision casting molds) with high requirements for hardness, wear resistance, and high temperature resistance, but it should be selected with caution in scenarios with large impact loads, conductivity or low cost.
Selection suggestions:
Prioritize: high temperature, high wear resistance, and high precision molds.
Avoid using: scenarios with frequent impact, complex shapes or limited budget.
By weighing its advantages and disadvantages and actual needs, calcined brown corundum is still an irreplaceable high-performance material in specific fields.