1. Electronic information materials
Semiconductor substrate:
Sapphire (α - Al ₂ O3) substrates are used for LED chips (accounting for 85% of the global LED substrate market), with a lattice constant of 4.758 Å, C=12.991 Å) has high compatibility with GaN and wafer curvature<50 μ m.
High purity alumina ceramic substrate (Al ₂ O ∝ ≥ 99.6%) with a thermal conductivity of 20-25 W/(m · K), used for power module heat dissipation, can reduce junction temperature by 15-20 ℃.
Capacitor dielectric:
The γ - Al ₂ O3 thin film serves as the dielectric layer for electrolytic capacitors, with a dielectric constant of 10-12, a leakage current of<10 ⁻⁷ A/cm ², and a withstand voltage strength of>50 V/μ m.
2. Energy and Environment
Fuel cell:
The electrolyte membrane of solid oxide fuel cell (SOFC) adopts yttrium stabilized zirconia (YSZ) - alumina composite coating, with oxygen ion conductivity of 0.1 S/cm (800 ℃) and power density>0.8 W/cm ².
In aluminum air batteries, alumina serves as the cathode catalyst carrier to enhance the activity of O ₂ reduction reaction (ORR), with an energy density of up to 500 Wh/kg.
Catalytic carrier:
The Pt/Pd catalyst loaded with γ - Al ₂ O ∝ is used for automobile exhaust treatment, with a specific surface area>150 m ²/g, CO conversion rate>95% (250 ℃), and a lifespan of over 80000 kilometers.
3. Structural ceramics and composite materials
High performance ceramics:
Aluminum oxide ceramics (Al ₂ O ∝ ≥ 90%) have a bending strength of>300 MPa and a fracture toughness of 3-5 MPa · m ¹/². They are used for cutting tools (speed>20000 rpm) and ceramic bearings (with a lifespan three times longer than steel bearings).
Transparent alumina ceramics (transmittance>85% @ 400-2000 nm) are used for missile infrared windows and can withstand temperature gradient changes of 200 ℃.
Composite material reinforcement phase:
Nano alumina particles (50 nm) doped with epoxy resin increase tensile strength by 40% and glass transition temperature (Tg) by 25 ℃, suitable for high-end copper-clad laminates.
4. Metallurgy and Refractory Materials
Aluminum smelting:
As the main component of cryolite melt, reducing the melting point of Al ₂ O3 (from 2054 ℃ to 950 ℃) increases the current efficiency to over 90%.
Refractory materials:
Alumina refractory bricks (Al ₂ O ∝ ≥ 85%) with a load softening temperature>1750 ℃, used for blast furnace lining and glass kilns, with a service life>5 years.