Dielectric Strength of Advanced Ceramics

Dielectric strength, also known as breakdown voltage, is the maximum electric field a material can sustain before becoming conductive. Measured in kV/mm (or MV/m), it’s crucial for ensuring the reliability of insulators in electronic, high-voltage, and thermal applications. This article explores the dielectric performance of key ceramic materials alongside plastics and insulation-grade materials, provides visual comparison, and dives into why it matters.

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Твердость керамики: Свойства, сравнение и применение

What is Dielectric Strength?

Dielectric strength represents the maximum electric field a material endures without electrical breakdown. In solids, breakdown occurs when sufficient energy ionizes the structure, allowing current to flow. High dielectric strength is vital for preventing electric arcs, ensuring safety and longevity in devices.

Ceramics often outperform plastics and glass, offering dielectric strength ranging from 10–40 kV/mm, compared to plastics (1–3 kV/mm)

Safety note: Ceramics handle electric fields better but must be selected for thermal and mechanical compatibility.

Why is it a core indicator?

  • Ensures Insulation Safety

    In high-voltage, high-frequency, and vacuum environments, insufficient dielectric strength can result in breakdown or arc discharge.

  • Prolongs Product Lifespan

    High-dielectric-strength ceramics handle greater voltage loads without increasing component size.

  • Enhances System Reliability

    Especially critical in aerospace and medical systems where minor dielectric failure can cause system crashes or even safety hazards.

Key Insights

  • Ceramics vs Plastics & Liquids:

    High-purity ceramics (Al₂O₃, AlN, h‑BN, BeO) show dielectric strength in the range of 15–40 kV/mm—comparable or superior to plastics and far above liquids like transformer oil or air.

  • Material Differences:

    • h‑BN leads ceramics with ~40 kV/mm breakdown strength.
    • AlN and Al₂O₃ are commonly used as insulating substrates.
    • SiC, while hard, has significantly lower dielectric strength and is not ideal for high-voltage insulation.

  • Anisotropy Matters:

    • h‑BN exhibits orientation-dependent breakdown: up to 12 MV/cm parallel to the c-axis

Dielectric Strength of Ceramic Materials

Керамический материал Диэлектрическая прочность (кВ/мм) Характеристики
Оксид бериллия (BeO) ~27 kV/mm Exceptional thermal conductivity and high dielectric strength; used in high-power electronics.
Нитрид алюминия (AlN) ~20 kV/mm High thermal conductivity with excellent electrical insulation; ideal for microelectronics.
ZTA 20% 80 – 120 Zirconia toughened alumina with enhanced fracture toughness and moderate dielectric properties.
Нитрид кремния (Si3N4) ~15 kV/mm High mechanical strength and thermal shock resistance; used in demanding environments.
Нитрид бора (BN) 40 kV/mm Excellent thermal stability and electrical insulation; often used in RF and vacuum applications.
Обрабатываемая стеклокерамика (MGC) ~15 kV/mm Easily machinable while maintaining electrical insulation; suitable for prototyping and custom shapes.
Карбид кремния (SiC) 2–10 kV/mm High hardness and thermal conductivity, but limited dielectric strength; used in high-temp applications.
Alumina (Al2O3, 96-99.7%) 17 kV/mm Widely used technical ceramic with balanced mechanical, thermal, and electrical properties.
Цирконий (ZrO2) ~9 kV/mm High strength and fracture toughness; lower dielectric strength but used where toughness is key.

*Данные приведены только для справки.

*Typically, dielectric properties will degrade significantly with increasing temperature.

Нужна помощь в выборе подходящей керамики?

Selecting the right ceramic material with high dielectric strength is critical to achieving long-term reliability and optimal electrical performance. Whether your application requires beryllium oxide, aluminum nitride, or alumina ceramics, our advanced ceramics deliver industry-leading performance and durability.

Our experienced technical team is ready to provide expert, customized guidance based on your unique design and performance requirements—contact us today.

Dielectric Strength Comparison

Below is a bar chart comparing the dielectric strength of advanced ceramics with plastics and common insulators.

Керамика
Пластик
Insulation Fluid/Air

*Данные приведены только для справки.

Applications based on ceramic Dielectric Strength

  • Material: Alumina (Al₂O₃), dielectric strength: 10–15 kV/mm
  • Applications: High-voltage vacuum circuit breakers, substation insulators, insulating rings
  • Case Study: In a 500kV UHV transmission project, 99.5% pure alumina insulators operated reliably between -40°C and 250°C without dielectric breakdown.
  • Advantages: High dielectric strength, thermal stability, excellent aging resistance

  • Material: Aluminum Nitride (AlN), dielectric strength: 12–15 kV/mm, thermal conductivity: 170–200 W/m·K
  • Applications: RF modules, power semiconductor packaging, 5G communication equipment
  • Case Study: In a 5G base station power amplifier, AlN substrates replaced alumina to significantly enhance heat dissipation and dielectric reliability, supporting stable RF output up to 120W.
  • Advantages: High dielectric strength, low dielectric constant at high frequency, high thermal conductivity

  • Material: Stabilized Zirconia (ZrO₂), dielectric strength: 8–12 kV/mm
  • Applications: X-ray tube housings in CT scanners, detector isolation structures
  • Case Study: A high-end CT system used zirconia ceramic housings for its X-ray tubes, eliminating arc discharge issues from metal housings and improving image stability and service life.
  • Advantages: Excellent electrical insulation, high mechanical strength, precision machinability

  • Material: Silicon Nitride (Si₃N₄) or Silicon Carbide (SiC); dielectric strengths: ~15 kV/mm and 20–30 kV/mm respectively
  • Applications: Microwave waveguide insulation in aerospace communication systems
  • Case Study: A ground station’s microwave waveguide incorporated hot-pressed SiC ceramics as insulating structures, preventing signal loss due to electric field breakdown.
  • Advantages: High dielectric strength, thermal shock resistance, plasma corrosion resistance

  • Material: Machinable Glass Ceramic (MGC)
  • Applications: Electrostatic capacitor housings, capacitive sensor bases
  • Case Study: In an aerospace electrical system, miniature capacitors using MGC for insulation housing withstood high voltages while operating from -200°C to 800°C.
  • Advantages: Extremely high dielectric strength, easy to machine, ultra-low thermal expansion

Related high Dielectric Strength ceramics

Керамика из нитрида бора - термостойкая керамика

Керамика на основе нитрида бора

Керамика на основе оксида бериллия с высокой теплопроводностью

Керамика из оксида бериллия

Керамика из нитрида алюминия с высокой теплопроводностью

Керамика на основе нитрида алюминия

Алюмооксидная керамика - термостойкая керамика

Глиноземистая керамика

Часто задаваемые вопросы (FAQ)

Нитрид бора (h-BN) achieves up to 40 kV/mm, rivaling or surpassing high-performance plastics or insulation liquids

It prevents insulation breakdown and short circuits. Higher strength = smaller insulation thickness needed, saving space and cost.

SiC is semiconducting at high fields, making it unsuitable for pure insulation applications despite mechanical strength.

Thickness, impurities, temperature, humidity, and electrode geometry influence real-world breakdown values.

Теплопроводность керамики из карбида кремния

Прочность на изгиб