Kovar Alloy is a nickel-iron-cobalt alloy with a coefficient of thermal expansion like that of hard glass. Since Kovar Alloy is tough and versatile, while employing extensive quality controls throughout UNS K94610 alloy’s manufacturing process to ensure uniform physical and mechanical properties for ease in deep drawing, stamping and machining are consistently achieved.
The coefficient of thermal expansion (CTE) of Kovar is its most dynamic mechanical property. It’s expansion characteristics match both borosilicate (or Pyrex) glasses and alumina ceramics. This alone ensures it is a highly popular controlled expansion alloys for hermetic sealing applications (also known as Glass to Metals Sealing)
Kovar is a nickel-iron-cobalt alloy known for its low coefficient of thermal expansion (CTE). It is commonly used in applications where a tight hermetic seal between different materials is required, especially in electronic and electrical components. A Kovar capillary tube refers to a small-diameter tube made from the Kovar alloy.
The capillary tube’s primary purpose is to serve as a hermetic feedthrough or a conduit for gases, liquids, or other substances in a controlled manner. The use of Kovar for capillary tubes is advantageous due to its CTE match with certain glass or ceramic materials, such as borosilicate glass or alumina, which allows for reliable sealing and prevents leaks or damage due to thermal expansion mismatch.
Kovar capillary tubes are often used in applications such as:
- Glass-to-metal seals: Kovar tubes are used to provide a hermetic seal between glass and metal components, commonly found in electronic packages, vacuum tubes, and light bulbs. The Kovar capillary tube helps ensure a secure and reliable bond between the glass envelope and the metal components.
- Thermal expansion control: Kovar’s low CTE makes it suitable for controlling thermal expansion in various applications. By using Kovar tubes, the differential thermal expansion between different materials can be minimized, reducing the risk of stress or damage to the components.
- High-reliability applications: Kovar tubes find use in high-reliability applications where precision, stability, and long-term performance are critical. Examples include aerospace, telecommunications, medical devices, and scientific instruments.
- Kovar capillary tubes are typically manufactured with tight dimensional tolerances and precise internal diameters to meet specific application requirements. These tubes can be customized in terms of length, diameter, and wall thickness to suit the specific needs of the application.
It’s important to note that Kovar is a trademarked name for an alloy designated as ASTM F15. When seeking Kovar capillary tubes, it’s advisable to consult with manufacturers or suppliers specializing in high-quality alloys and precision components to ensure the desired specifications and performance.
- Reliable hermetic sealing applications
- Precise and uniform thermal expansion characteristics
- Their coefficient thermal expansion makes the seal resistant to shock and cracking
Kovar Chemical Composition
Kovar Physical Properties
|Density||Curie Temp||Melting Point||Modulus of Elasticity at 20°C||Specific Heat||Thermal Conductivity at 20°C||Thermal Expansion||Electrical Resistivity||Poisson's coefficient|
|8.36 g/cm³||435°C ( 815°F)||1450°C (2460°F)||207 MPa||0.11 J/g- °C||17.3 W/m.k||0.17W.m-¹°C||49 mm²/m||0.317|
|Yield Strength,MPa||Tensile Strength,MPa||% Elongation in 2"||Hardness Rockwell B|
|Flux Density||1830°F (999°C) 30 min. - FC Permeability||2010°F (1099°C) 20 min. - FC Permeability|
Kovar capillary tubes are made of a nickel-iron-cobalt alloy that has a very low thermal expansion coefficient. This makes them well-suited for applications where a close seal is required between a metal and a glass component. Kovar capillary tubes are often used in microwave devices, vacuum tubes, and other electronic components.
Properties of Kovar capillary tubes:
- Material: Nickel-iron-cobalt alloy
- Melting point: 1453°C (2646°F)
- Tensile strength: 480 MPa (70,000 psi)
- Corrosion resistance: Good
- Operating temperature range: -200°C to 1250°C (-330°F to 2282°F)
- Thermal expansion coefficient: 5.7 × 10^-6/°C (11.6 × 10^-6/°F)
Safety precautions for working with Kovar capillary tubes:
- Wear protective clothing. This includes long sleeves, pants, gloves, and a face shield.
- Work in a well-ventilated area. Kovar tubes can emit fumes that can be harmful if inhaled.
- Avoid contact with the skin. If Kovar capillary tubes come into contact with your skin, wash it immediately with soap and water.
- Do not weld or braze Kovar tubes in a confined space. The fumes can build up and create a dangerous environment.
- Dispose of Kovar tubes properly. Do not burn or bury them, as this could release harmful fumes.
Here are some additional safety precautions that may be relevant depending on your specific work environment:
- Use a fire extinguisher in case of a fire.
- Have a first-aid kit on hand in case of an accident.
- Train employees on the proper handling of Kovar capillary tubes.
- By following these safety precautions, you can help to ensure a safe and productive work environment.
Here are some additional details about the specific safety hazards associated with Kovar capillary tubes:
- Fumes: Kovar capillary tubes can emit fumes that can be harmful if inhaled. These fumes can cause respiratory problems, such as coughing, wheezing, and shortness of breath. They can also cause skin irritation and eye problems.
- Fire: Kovar tubes can be easily ignited. If they come into contact with a spark or flame, they can quickly catch fire. This can be a serious hazard, as the flames can spread quickly and cause burns.
- Toxicity: Kovar capillary tubes contain nickel, which is a toxic metal. If Kovar capillary tubes are ingested or inhaled, they can cause serious health problems, such as liver damage and cancer.
It is important to be aware of these safety hazards and take the necessary precautions to protect yourself when working with Kovar capillary tubes. By following the safety precautions outlined above, you can help to prevent accidents and injuries.
- Bars & Rods & Foring Ring /Flanges
- Sheet & Plate
- Strip & Coil
- Welding Wire &Spring wire
- Seamless Tube & Welded Pipe
»Round Bar & Square Bar & Hexagon Bar
● Diameter : φ8～φ300mm Length:10mm-6000mm
● Hot forging, Hot Rolling, Cold Drawing
● Bright Surface, Polished Surface, Black Surface
»Tube & Pipe:Seamless Tube& Welded Pipe
● Cold Drawing Seamless Pipe： φ1.0～φ220mm
● Hot Extrusion pipe: φ50～φ250mm
● Others : U Blend Tube and Elbow
»Hot Rolled Plate & Cold Rolled Sheet
● Cold Rolling Sheet Thickness: ≦2.0mm Width:≦1500m
● Hot rolling Plate Thickness: ≧4.0mm Width: ≦2500m
»Strip & Tape Ribbon
● Thickness: ≧ 0.01mm Width: 15mm-300mm
● Cold rolling BA Strip, Hard & Soft Condition
»Straight Length Wire & Spool Wire
● Welding Wire: φ 0.1mm～6.0mm Cut length Rod: φ1.0～φ8.0mm
● Package : 5-25kg/Spool or Box
- Hermetic sealing
- Production of transistors and diodes in electronic industry
- Vacuum systems in chemistry and scientific research
- Electronic tubes (power, X-Ray)
- Hybrid circuit casings
- Oscillator housings
- Concentrated solar power
- Scientific instruments
Cleaning and maintenance of Kovar capillary tubes are essential to ensure their optimal performance and longevity. Kovar, a nickel-iron-cobalt alloy, is commonly used in applications where a hermetic seal is required, such as in electronic and electrical components. Here are some guidelines for cleaning and maintaining Kovar capillary tubes:
When handling Kovar capillary tubes, it is important to wear clean gloves to prevent contamination from oils, dirt, or moisture on the hands. This helps maintain the cleanliness of the tubes and prevents potential corrosion or surface damage.
Before cleaning Kovar capillary tubes, it is advisable to refer to the manufacturer’s guidelines or consult with experts familiar with the specific application. However, here is a general cleaning procedure:
a. Use a lint-free cloth or swab moistened with a mild detergent or solvent recommended for use with Kovar. Avoid using abrasive cleaners or materials that could scratch or damage the surface.
b. Gently wipe the exterior of the capillary tube, ensuring the removal of any dirt, oils, or contaminants. Take care not to apply excessive pressure that could deform or bend the tube.
c. Rinse the capillary tube with clean water or a solvent, if required, to remove any residue from the cleaning agent.
d. Dry the tube thoroughly using a clean, lint-free cloth or allow it to air-dry in a controlled environment to prevent the formation of water spots.
Proper storage of Kovar capillary tubes is crucial to maintain their integrity. Consider the following guidelines:
a. Store the capillary tubes in a clean and dry environment to prevent exposure to moisture, which can lead to corrosion.
b. Use protective caps or covers on the ends of the tubes to prevent dust, debris, or other contaminants from entering.
c. If the capillary tubes are to be stored for an extended period, consider using desiccant packs or other humidity control measures to maintain low humidity levels.
Inspection and Maintenance:
Regular inspection of Kovar capillary tubes is recommended to identify any signs of damage, corrosion, or degradation. If any issues are detected, consult with experts or the manufacturer for appropriate maintenance or replacement procedures.
Avoidance of Harsh Environments:
Kovar capillary tubes should be used within their specified temperature and environmental limits. Exposure to extreme temperatures, corrosive chemicals, or harsh environments can adversely affect the performance and integrity of the tubes. Ensure that the capillary tubes are not subjected to conditions beyond their design capabilities.
By following these cleaning and maintenance guidelines, you can help preserve the performance and longevity of Kovar capillary tubes, ensuring their continued reliability in critical applications. It is crucial to consult with experts or refer to specific manufacturer recommendations for cleaning and maintenance procedures tailored to the unique requirements of your Kovar capillary tubes.