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

Procurement Evaluation Criteria

Not customer reviews or live demand data. These dimensions support RFQ preparation and supplier evaluation.

Technical documentation
4/5
Manufacturing capability
4/5
Inspection readiness
5/5
Supplier transparency
3/5

These scores are example evaluation dimensions, not real customer ratings, country-specific buyer feedback, or live inquiry activity.

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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.

Data Basis

CNFX manufacturer profiles, technical classification, publicly available product information, and ongoing plausibility checks.

Preliminary Technical Classification
This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

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