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Kovar Low Expansion Alloys 4J29 Strip Glass - To - Metal Seal For Light Bulbs

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Ohmalloy Material Co.,Ltd
City: Shanghai
Province/State: Shanghai
Country/Region: China
Tel: 86-21-66796338
Contact Person:
Mr Qiu

Kovar Low Expansion Alloys 4J29 Strip Glass - To - Metal Seal For Light Bulbs

Brand Name : OHMALLOY
Model Number : 4J29
Certification : ISO
Place of Origin : China(Shanghai)
MOQ : 20kg
Price : negotiable
Supply Ability : 5000kg/month
Packaging Details : In Coil
Material : 4J29
Supply Type : Strip
Color : Primary Color
Surface : Bright and Smooth
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OhmAlloy-4J29 (Expansion alloy)
(Common Name: Kovar, Nilo K, KV-1, Dilver Po, Vacon 12)

OhmAlloy-4J29 also known as Kovar alloy. it was invented to meet the need for a reliable glass-to-metal seal, which is required in electronic devices such as light bulbs, vacuum tubes, cathode ray tubes, and in vacuum systems in chemistry and other scientific research. Most metals cannot seal to glass because their coefficient of thermal expansion is not the same as glass, so as the joint cools after fabrication the stresses due to the differential expansion rates of the glass and metal cause the joint to crack.


Kovar is a nickel–cobalt ferrous alloy compositionally identical to Fernico, designed to be compatible with the thermal expansion characteristics of borosilicate glass (~5 × 10−6 /K between 30 and 200 °C, to ~10 × 10−6 /K at 800 °C) in order to allow direct mechanical connections over a range of temperatures. It finds application in electroplated conductors entering glass envelopes of electronic parts such as vacuum tubes (valves), X-ray and microwave tubes and some lightbulbs.

The name Kovar is often used as a general term for Fe–Ni alloys with these particular thermal expansion properties. Note the related particular Fe–Ni alloy Invar which exhibits minimum thermal expansion.


OhmAlloy-4J29was invented to meet the need for a reliable glass-to-metal seal, which is required in electronic devices such as light bulbs, vacuum tubes, cathode ray tubes, and in vacuum systems in chemistry and other scientific research. Most metals cannot seal to glass because their coefficient of thermal expansion is not the same as glass, so as the joint cools after fabrication the stresses due to the differential expansion rates of the glass and metal cause the joint to crack.


OhmAlloy-4J29 not only has thermal expansion similar to glass, but its nonlinear thermal expansion curve can often be made to match a glass, thus allowing the joint to tolerate a wide temperature range. Chemically, it bonds to glass via the intermediate oxide layer of nickel oxide and cobalt oxide; the proportion of iron oxide is low due to its reduction with cobalt. The bond strength is highly dependent on the oxide layer thickness and character. The presence of cobalt makes the oxide layer easier to melt and dissolve in the molten glass. A grey, grey-blue or grey-brown color indicates a good seal. A metallic color indicates lack of oxide, while black color indicates overly oxidized metal, in both cases leading to a weak joint.


Mainly used in electric vacuum components and emission control, shock tube, igniting tube, glass magnetron, transistors, seal plug, relay, integrated circuits lead, chassis, brackets and other housing sealing.


KOVAR STRIP MATERIAL:https://www.youtube.com/watch?v=rUOQtkjdYlo

Normal composition%

Ni28.5~29.5FeBal.Co16.8~17.8Si≤0.3
Mo≤0.2Cu≤0.2Cr≤0.2Mn≤0.5
C≤0.03P≤0.02S≤0.02

Tensile Strength, MPa

Code of conditionConditionWireStrip
RSoft≤585≤570
1/4I1/4 Hard585~725520~630
1/2I1/2 Hard655~795590~700
3/4I3/4 Hard725~860600~770
IHard≥850≥700

Typical Physical properties

Density (g/cm3)8.2
Electrical resistivity at 20℃(Ωmm2/m)0.48
Temperature factor of resistivity(20℃~100℃)X10-5/℃3.7~3.9
Curie point Tc/ ℃430
Elastic Modulus, E/ Gpa138

Coefficient of expansion

θ/℃α1/10-6-1θ/℃α1/10-6-1
20~607.820~5006.2
20~1006.420~5507.1

Sales Manager:Michaeal Qiu.

What's App:+86 13795230939

Tel:+86-21-66796338 Mobile Phone: +86 13795230939


Product Tags:

invar alloy

      

thermal expansion invar

      
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Kovar Low Expansion Alloys 4J29 Strip Glass - To - Metal Seal For Light Bulbs Images

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