INDUSTRY COMPONENT

Glass or Metal-Ceramic Envelope

A vacuum-tight envelope for X-ray tubes, made of glass or metal-ceramic, providing electrical insulation and structural integrity.

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Component Specifications

Definition
The glass or metal-ceramic envelope is a critical component of an X-ray tube, serving as a hermetic, vacuum-tight housing that contains the cathode, anode, and internal vacuum environment. It provides high-voltage electrical insulation between internal electrodes, maintains structural stability under thermal stress, and allows X-ray transmission through designated windows while preventing atmospheric contamination.
Working Principle
The envelope maintains a high vacuum (typically 10^-6 to 10^-8 Torr) to prevent arcing and electron scattering, while providing dielectric strength to withstand tube voltages up to 150 kV. It must withstand thermal expansion from anode temperatures reaching 2500°C, with cooling mechanisms to manage heat dissipation. The material choice balances X-ray transparency, mechanical strength, and electrical insulation properties.
Materials
Glass: Borosilicate glass (e.g., Pyrex) for thermal shock resistance; Metal-ceramic: Kovar (iron-nickel-cobalt alloy) brazed to alumina or beryllia ceramics using copper-silver eutectic alloys; Beryllium windows for high X-ray transmission in specific applications.
Technical Parameters
  • Vacuum Leak Rate <10^-9 mbar·L/s
  • X-ray Transmission >70% at 50 keV (for window areas)
  • Dielectric Strength ≥30 kV/mm
  • Operating Temperature -20°C to 300°C
  • Thermal Expansion Coefficient 3-7 × 10^-6/K (matched to electrodes)
Standards
ISO 16526, DIN 6836, IEC 60601-2-28

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Glass or Metal-Ceramic Envelope.

X-ray tube envelope glass envelope metal-ceramic housing vacuum tube component dielectric insulation X-ray window beryllium window high voltage insulation Glass or Metal-Ceramic Envelope Glass or Metal-Ceramic Envelope in Computer, Electronic and Optical Product Manufacturing

Parent Products

This component is used in the following industrial products

X-ray Tube

A vacuum tube that generates X-rays by accelerating electrons to strike a metal target.

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Engineering Analysis

Risks & Mitigation
  • Dielectric breakdown under high voltage
  • Thermal stress cracking
  • Vacuum leakage compromising tube performance
  • Beryllium toxicity during manufacturing (if used)
FMEA Triads
Trigger: Thermal cycling stress
Failure: Crack formation leading to vacuum loss
Mitigation: Use materials with matched thermal expansion coefficients; implement gradual heating/cooling cycles
Trigger: Manufacturing defects in brazing joints
Failure: Hermetic seal failure
Mitigation: Non-destructive testing (helium leak detection); quality control of brazing parameters

Industrial Ecosystem

Compatible With

Interchangeable Parts

Compliance & Inspection

Tolerance
Dimensional tolerance ±0.1 mm; surface roughness Ra ≤0.8 μm for sealing surfaces
Test Method
Helium mass spectrometry leak testing per ASTM E493; high-potential testing at 1.5× rated voltage; thermal cycling tests per IEC 60601

Buyer Feedback

★★★★☆ 4.9 / 5.0 (29 reviews)

"The Glass or Metal-Ceramic Envelope we sourced perfectly fits our Computer, Electronic and Optical Product Manufacturing production line requirements."

"Found 37+ suppliers for Glass or Metal-Ceramic Envelope on CNFX, but this spec remains the most cost-effective."

"The technical documentation for this Glass or Metal-Ceramic Envelope is very thorough, especially regarding technical reliability."

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Frequently Asked Questions

What are the advantages of metal-ceramic envelopes over glass envelopes?

Metal-ceramic envelopes offer superior mechanical strength, better thermal conductivity, higher temperature tolerance, and improved resistance to thermal shock, making them suitable for high-power and rotating anode X-ray tubes.

Why is vacuum integrity critical for X-ray tube envelopes?

Vacuum integrity prevents electrical arcing between electrodes, minimizes electron scattering that reduces X-ray output efficiency, and prevents oxidation of hot components like the tungsten anode.

Can I contact factories directly?

Yes, each factory profile provides direct contact information.

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