Tonerde-Keramik: Eigenschaften für technische Anwendungen

Einführung

Alumina ceramics (Al₂O₃), or aluminum oxide, are advanced non-metallic materials known for their mechanical strength, thermal stability, and electrical insulation. Available in purities of 95%, 97.5%, 99%, and 99.5% Al₂O₃, these ceramics are ideal for engineering applications in electronics, mechanical systems, and thermal management. This article details the key properties of alumina ceramics, supported by a comparative table, to highlight their suitability for engineering solutions.

Properties of Alumina Ceramics

Alumina ceramics offer a range of mechanical, thermal, electrical, and chemical properties, making them suitable for demanding engineering applications. Below are their primary characteristics:

• Hohe Härte: Vickers hardness ranges from 13.7 GPa (95% Al₂O₃) to 17.5 GPa (99.5% Al₂O₃), ideal for wear-resistant components.
• Mechanische Festigkeit: Flexural strength from 310 MPa (97.5% Al₂O₃) to 400 MPa (99.5% Al₂O₃), suitable for load-bearing applications.
• Wärmeleitfähigkeit: Ranges from 24 W/(m·K) (95% Al₂O₃) to 34 W/(m·K) (99.5% Al₂O₃), supporting heat dissipation.
• Elektrische Isolierung: Volume resistivity >10¹⁴ ohm-cm across all grades, ensuring reliability in electronic systems.
• Corrosion Resistance: Minimal weight loss in acids (e.g., 0.03 mg/cm²/day in HNO₃ for 99.5% Al₂O₃), perfect for harsh environments.

Detaillierte Eigenschaftstabelle

The table below compares the properties of alumina ceramics across 95%, 97.5%, 99%, and 99.5% Al₂O₃ grades.

Eigentum	95% Al₂O₃	97.5% Al₂O₃	99% Al₂O₃	99.5% Al₂O₃
Main Characteristics
Farbe	Weiß	Weiß	Weiß	Weiß
Main Applications	Metallization, wear resistance	High wear resistance	High temperature, wear resistance	High temperature, wear resistance
Characteristics	High strength, wear resistance, corrosion resistance, insulation	High strength, corrosion resistance	High strength, corrosion resistance	High strength, corrosion resistance
Mechanische Eigenschaften
Bulk Density (g/cm³)	3.7	3.8	3.9	3.9
Water Absorption (%)	0	0	0	0
Vickers Hardness (GPa)	13.7	15.2	17.2	17.5
Biegefestigkeit (MPa)	350	310	380	400
Compressive Strength (MPa)	—	—	—	3800
Young’s Modulus (GPa)	320	360	380	380
Poisson’s Ratio	0.23	0.23	0.23	0.23
Fracture Toughness (MPa m¹/²)	3–4	5–6	—	—
Thermische Eigenschaften
Specific Heat Capacity (J/(kg·K) × 10⁻³, 400°C)	7.2	7.2	7.2	7.2
Thermal Conductivity (W/(m·K))	24	25	32	34
Thermal Shock Resistance (ΔT°C)	200	200	200	200
Elektrische Eigenschaften
Volumenwiderstand (ohm-cm)	>10¹⁴	>10¹⁴	>10¹⁴	>10¹⁴
Dielectric Strength (kV/mm)	15	15	15	15
Dielectric Constant (1 MHz)	9.4	9.9	9.9	9.9
Dielectric Loss (×10⁻⁴)	38	20	10	10
Chemical Properties
Nitric Acid (60%) Weight Loss (mg/cm²/day)	0.10	0.05	0.03	0.03
Sulfuric Acid (95%) Weight Loss (mg/cm²/day)	0.33	0.22	0.19	0.19
Caustic Soda (30%) Weight Loss (mg/cm²/day)	0.06	0.04	0.03	0.03

Tabelle Anmerkungen:

• Mechanische Eigenschaften: Higher-purity grades (99% and 99.5% Al₂O₃) offer increased hardness (17.2–17.5 GPa) and flexural strength (380–400 MPa).
• Thermische Eigenschaften: Thermal conductivity improves with purity, from 24 W/(m·K) to 34 W/(m·K).
• Chemische Beständigkeit: Higher purity reduces weight loss in acids, enhancing corrosion resistance.

Schlussfolgerung

Alumina ceramics offer exceptional mechanical strength, thermal stability, and electrical insulation, making them ideal for engineering applications in electronics, mechanical systems, and thermal management. The range of purities allows for tailored solutions in demanding environments.

Zentrum für Hochleistungskeramik is a leading manufacturer and supplier of high-quality alumina ceramic products in forms of plates, sheets, rods, tubes, crucibles, substrates, and customized parts, offering customized solutions for various industrial and research applications.