BDD Ultra high temperature heater

 

Boron-Doped Diamond (BDD) Ultra-High Temperature Heater

1. Material Advantages and Core Properties

Boron-Doped Diamond (BDD) is an emerging functional material combining ultra-high temperature stability, tunable electrical conductivity, and exceptional chemical inertness, making it ideal for heating in extreme environments.

■ Ultra-High Temperature Stability
In-situ high-temperature XRD shows that BDD maintains crystal integrity at 2000 °C, while pure diamond begins graphitization near 1400 °C. Boron incorporation strengthens C–C bonds and densifies the lattice.

■ Tunable Electrical Properties
At boron concentrations of 10¹⁸–10²¹ atoms/cm³:

• Conductivity: 10⁻² → 10³ S/cm

• Semiconductor-to-metal transition behavior

• Stable high-temperature TCR: ±0.05%/°C

• Significantly better than platinum (~0.39%/°C)

This enables precise power control and temperature regulation.

■ Extreme Chemical Stability
In strong acid environments at 800 °C:

• Corrosion rate < 10⁻⁹ g/(cm²·h)

• ~1000× lower than SiC

Suitable for halogen, acidic, and highly corrosive atmospheres.

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2. Key Manufacturing Technologies

2.1 BDD Film Deposition

Primary method: Microwave Plasma Chemical Vapor Deposition (MPCVD)

Key parameters:

• Microwave power: 3.5–4.5 kW

• Plasma density: 10¹¹–10¹² cm⁻³

• CH₄ concentration: 1–3%

• B₂H₆/CH₄ ratio: 0.1–1.0

Advances include hot-filament-assisted MPCVD for ±2 °C temperature uniformity and MPCVD + ALD for conformal coatings on complex 3D geometries.

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2.2 Heater Structure Design

Spiral layouts provide ±3 °C temperature uniformity; serpentine designs enable faster thermal response.

Substrate selection:

• Sapphire (Al₂O₃): <1800 °C applications

• Stabilized zirconia (ZrO₂): >1800 °C environments

A Ti interlayer improves adhesion strength up to 45 MPa.

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2.3 Lead and Packaging Technology

Ti/Pt/W graded metallization ensures reliable high-temperature electrical contacts.
Nb-10Hf alloy leads retain 400 MPa tensile strength at 2000 °C and offer improved thermal expansion matching.
Mo-Mn metallized ceramic packaging achieves hermetic sealing (<10⁻¹⁰ Pa·m³/s leak rate).

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3. Performance Under Extreme Conditions

• 1800 °C continuous operation (100 h) with ±4.2 °C fluctuation

• 5 GPa / 1500 °C testing shows only 3.7% resistance change

• Corrosion depth <5 nm in aggressive environments at 1000 °C

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4. Application Prospects

BDD heaters enable:

• Aerospace thermal protection and ablation simulation

• Molten-salt thermal energy storage testing

• 3000 °C extreme-condition scientific research

• Corrosion-resistant industrial processing systems

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5. Key Challenges

PECVD processes may reduce cost by ~30%, though film quality requires improvement.
Above 2500 °C, boron diffusion and surface graphitization may occur; DLC protective coatings can extend stability to ~2800 °C.
International Organization for Standardization is developing standardized performance testing methods.

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6. Industrial Capability

SEMIXICON DIASEMI provides advanced MPCVD diamond deposition and DLC coating technologies, supporting precision ceramics and diamond-based solutions for semiconductor, energy, aerospace, and extreme-environment applications.