Metallized Alumina Ceramic Tube for Hermetic Brazing & High-Voltage Insulation

Metallized Alumina Ceramics Tube Applications

• Vacuum & High-Voltage Feedthroughs

  ✅Key Advantages

  1. Defined band wetting — Stable capillary fill reduces braze voids and rework.
  2. Leak-tight joints — Supports assembly targets down to 1×10⁻⁹ mbar·L/s.
  3. Compact insulation — ≥10 kV/mm dielectric enables shorter creepage paths.

  ✅ Problem Solved

  A HV analyzer retrofitted its feedthrough using a metallized alumina ceramic tube with a 2.5 mm-wide band at 6.0 mm from the end, Mo-Mn 15 µm + Ni 6 µm. First-pass helium test reached ≤5×10⁻¹⁰ mbar·L/s; runout improved from 0.12 mm to 0.06 mm, cutting assembly rework by 30% and shortening qualification by 2 weeks.

• UV/IR Lamp & Ozone Generator Ends

  ✅Key Advantages

  1. Repeatable end sealing — Band position tolerance ±0.2 mm improves lamp-end uniformity.
  2. Thermal resilience — Al₂O₃ tube maintains geometry near 800–1,000 °C system exposure.
  3. Electrical isolation — Controlled creepage supports compact lampholder designs.

  ✅ Problem Solved

  A chlorination off-gas reactor showed ±18% temperature spread and weekly cleaning due to corroded stainless diffusers. After switching to a porous alumina diffusion rod (5 µm pore, Ø20 × 300 mm), gas distribution deviation fell to 6% and ΔP stabilized <18 kPa at 40 L/min.Material loss was not measurable after 500 h exposure to 10% HCl vapour; porosity and flow stayed within spec. Maintenance interval extended from 4 weeks to 12 weeks, saving ~32 h downtime per quarter and reducing spare-part spend by ~30%.

• Laser/Analytics Sensor Interfaces

  ✅Key Advantages

  1. Small-form factor — Thin-wall tubes enable micro-bore channels without losing stiffness.
  2. Low particle surfaces — Lapped ends reduce particulates during clean build.
  3. Stable alignment — Coaxiality control ≤0.10 mm improves optical alignment yield.

  ✅ Problem Solved

  A spectrometry module used a 6×4×80 mm tube; with band mapping and lapped ends, optical alignment yield rose from 88% to 96%, and field returns dropped 40% over two quarters.

Metallized Alumina Ceramics Tube Usage Instructions

• Installation

  1. Verify metallized band alignment:
  Check band position against the fixture or ferrule design before assembly. Perform a dry-fit test to confirm joint concentricity and braze gap clearance.
  2. Surface preparation:
  Degrease metallized or nickel-plated areas using isopropyl alcohol (IPA) or approved solvent; avoid direct contact with fingers to prevent surface oils that reduce wetting.
  3. Joint fit and tolerance control:
  Maintain radial clearance and joint gap as defined in the brazing alloy specification (typically 0.05–0.15 mm). Ensure full contact without stress points.
  4. Pre-braze inspection:
  Check for cracks, scratches, or flaking in the metallized zone. Replace parts with visible defects before brazing.
  5. Fixture support:
  Use graphite or alumina jigs to support the tube during brazing, avoiding metal clamps that may distort or scratch the surface.

• Operation

  1. Maintain electrical and thermal safety:
  Observe required high-voltage creepage distances and prevent metallic contamination on exposed ceramic surfaces.
  2. Temperature control:
  Follow brazing or sealing alloy heating profiles. Apply gradual heating and cooling to avoid thermal shock and differential expansion stress between ceramic and metal parts.
  3. Environmental stability:
  When used in vacuum or inert atmospheres, verify that leak-rate targets and dielectric insulation are achieved after brazing and cleaning.
  4. In-service inspection:
  Periodically monitor joint integrity and metallized area discoloration, which may indicate micro-leak or oxidation over time.

• Storage

  1. Environment: Store tubes in dry, dust-free cabinets or desiccated containers; relative humidity below 40% RH is preferred.
  2. Handling: Avoid stacking directly on metallized zones; use soft dividers or bubble wrap to prevent surface abrasion.
  3. Traceability: Maintain lot labels and production batch codes for later inspection or maintenance reference.

• Cleaning

  1. Routine maintenance: Wipe ceramic and metallized surfaces using lint-free wipes and non-corrosive solvents. Avoid abrasive pads, brushes, or strong acids on Ni-plated bands.
  2. Deep cleaning: If flux or oxide residue remains after brazing, use ultrasonic cleaning in neutral detergent solution for ≤3 minutes, then rinse with deionized water.
  3. Drying: Air-dry under filtered airflow or bake at 120°C for 30 minutes before storage or further processing.
  4. Handling caution: Always wear nitrile gloves and use clean tweezers; fingerprints on nickel zones can cause non-wetting during next brazing cycle.

Metallized Alumina Ceramics Tube FAQ

1. Q: What is the purpose of metallization on an alumina ceramic tube?
   A: Metallization allows the alumina tube to be brazed or soldered to metals such as Kovar, stainless steel, or 42-alloy. The Mo-Mn + Ni coating creates a bondable interface while the rest of the tube remains a high-dielectric ceramic insulator, ensuring both mechanical stability and hermetic sealing.

2. Q: What is the typical metallization system used for metallized alumina ceramic tubes?
   A: The standard system is Mo-Mn (10–25 µm) fired into the ceramic, followed by nickel plating (3–10 µm) for wetting. Optional overcoats like Ni + Au or Ni + Ag can be applied when higher brazing compatibility or oxidation resistance is needed.

3. Q: What purity of alumina is used, and how does it affect performance?
   A: Metallized tubes are typically made from 95–99.7% Al₂O₃. Higher purity improves dielectric strength, thermal conductivity, and resistance to ionic contamination, which are critical for vacuum feedthroughs and high-voltage insulation.

4. Q: How hermetic are metallized alumina ceramic tubes after brazing?
   A: When brazed under proper vacuum and alloy conditions, these tubes can achieve helium leak rates ≤1×10⁻⁹ mbar·L/s, meeting the requirements for hermetic electronic packages, vacuum devices, and gas-handling systems.
5. Q: What dimensions and tolerances can be achieved for metallized alumina ceramic tubes?
   A: Typical sizes range OD 6–32 mm, wall 0.6–3.0 mm, and lengths up to 300 mm (custom longer). Dimensional tolerances are ±0.05–0.20 mm, while band width and position can be held within ±0.1–0.3 mm depending on geometry.
6. Q: Can the metallized alumina ceramic tube be customized according to my drawing?
   A: Yes. ADCERAX supports fully custom designs, including specific band width, band spacing, Ni thickness, end geometry (chamfer, step, groove), and even multi-band or windowed patterns for selective brazing. A drawing or 3D model accelerates quotation and DFM evaluation.

Metallized Alumina Ceramic Tube Reviews

• ⭐️⭐️⭐️⭐️
  ADCERAX metallized alumina ceramic tubes brazed cleanly to Kovar parts. Dimensional accuracy ±0.1 mm and consistent leak-tight joints improved our vacuum assembly yield.
  -- John W., Procurement Manager, UltraVac Systems (USA)
• ⭐️⭐️⭐️⭐️⭐️
  Standard metallized alumina tubes matched our fixtures and tolerances. Good surface quality and fast delivery from the ADCERAX factory.
  -- Dr. Anna K., R&D Engineer, PhotonTech (Germany)
• ⭐️⭐️⭐️⭐️⭐️
  Nickel-plated metallized tubes maintained integrity through 500 thermal cycles. Ideal for our sealed sensor housings.
  -- Michael T., Operations Director, PowerPulse (UK)
• ⭐️⭐️⭐️⭐️⭐️
  Received custom 400 mm metallized alumina ceramic tubes on time. Precise machining, clear drawings, and smooth installation.
  --Yumi S., Process Engineer, NexGen Sensors (Japan)