China 4j29 Fe-Ni-Co Glass Sealing Alloy Glass Sealing Alloy Strip

Nilo K Kovar Alloy Foil Fe-Ni-Co Glass Sealing Alloy 4j29

Kovar4J29 (Expansion alloy)
(Common Name: Kovar, Nilo K, KV-1, Dilver Po,Vacon 12)

4J29 also known asKovaralloy. 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 x 10−6 /K between 30 and 200 °C, to ~10 x 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.

Kovarwas invented to meet the need for a reliable glass-to-metDrilling Rig al seal, which is required in electronic deMachinery for Food, Beverage & Cereal vices 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 dStamping ue to the differential expansion rates of the glass and metal cause the joint to crack.

Kovar 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 tubSpeaker,Trumpet & Buzzer e, glass magnetron, transistors, seal plug, relay, integrated circuits lead, chassis, brackets and other housing sealing.

Chemical composition4J29 bar

alloyCMnSiPSNiCrCoCuMoFe4J29≤0.03≤0.50≤0.30≤0.020≤0.02028.5~29.5≤0.2016.8~17.8≤0.2≤0.2balanceTensile Strength, MPaCode of conditionConditionWireStripRSoft≤585≤5701/4I1/4 Hard585~725520~6301/2I1/2 Hard655~795590~7003/4I3/4 Hard725~860600~770IHard≥850≥700Typical Physical propertiesDensity (g/cm3)8.2Electrical resistivity at 20ºC(OMmm2/m)0.48Temperature factor of resistivity(20ºC~100ºC)X10-5/ºC3.7~3.9Curie pointTc/ºC430Elastic Modulus,E/ Gpa138

The heat treatment process

Annealing for stress reliefHeated to 470~540ºC and hold 1~2 h. Cold downannealingIn vacuum heated to 750~900ºCHolding time14 min~1h.Cooling rateNo more than 10 ºC/min cooled to 200 ºC

Coefficient of expansion

θ/ºCα1/10-6ºC-1θ/ºCα1/10-6ºC-120~607.820~5006.220~1006.420~5507.120~2005.920~6007.820~3005.320~7009.220~4005.120~80010.220~4505.320~90011.4

Thermal conductivity

θ/ºC100200300400500λ/ W/(m*ºC)20.621.522.723.725.4

Style of supply

Alloys NameTypeDimension4J29WireD= 0.1~8mm4J29StripW= 5~250mmT= 0.1mm4J29FoilW= 10~100mmT= 0.01~0.1mm4J29BarDia= 8~100mm

L= 50~1000mm

FAQ

1. What's the minimum quantity customer can order?
If we have your size in stock, we can provide any quantity you want.
If we do not have, for spool wire, we can produce 1 spool, about 2-3kg. For coil wire, 25kg.2. How can you pay for small sample amount?
We have Western union account, wire transfer for sample amount also ok.3. Customer do not have express account. How will us arrange the delivery for sample order?
Just need to provide your address information, we will check the express cost, you can arrange the express cost together with sample value.4. What's our payment terms?
We can accept LC T/T payment terms, it also depending on delivery and total amount. Let's tTextile Machinery & Parts alk more in details after getting your detailed requirements.5. Do you provide free samples?
If you want several meters and we have stock of your size, we can provide, customer need to bear the International express cost.6. What's our working time?
We will give you reply through email/phone online contact tool within 24 hours. No matter working day or holidays.