4j29 Kovar Iron Nickel Cobalt Alloy Pipe Low Resistance Square / Round Tube Pipe

General Description:

4J29, is a nickel-cobalt ferrous alloy compositionally identical to Fernico 1, designed to have substantially the same thermal expansion characteristics as borosilicate glass (~5 × 10⁻⁶ /K between 30 and 200 °C, to ~10 × 10⁻⁶ /K at 800 °C) in order to allow a tight mechanical joint between the two materials over a range of temperatures. It finds application in glass-to-metal seals in scientific apparatus, and conductors entering glass envelopes of electronic parts such as vacuum tubes (valves), X-ray and microwave tubes and some lightbulbs.

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(II) oxide and cobalt(II) 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.

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.

Chemical Composition:

Main properties:

Style of supply:

Shanghai Tankii Alloy Material Co., Ltd.specialized in production of Resistance Heating Alloy, Nickel Chromium Alloy, Iron Chromium Aluminum Alloy, Nickel Aluminum Alloy, Manganin, Copper Nickel Alloy, thermocouple wire, pure nickel and other precision alloy materials in the form of round wire, ribbon wire, sheet, tape, strip, rod and plate.

We’ve already got ISO9001 quality system certificate and approval of ISO14001 environmental protection system.

We own a complete set of advanced production flow of refining, cold reduction, drawing and heat treating etc. We also proudly have independent R&D capacity.

Shanghai Tankii Alloy Material Co., Ltd has accumulated lots of experiences over forty years in this field. During forty years, hundreds of management elites and high science and technology talents were employed.They participated in every walk of the company life, which make our company keep blooming and invincible in the competitive market.

Based on the principle of “first quality, sincere service”, our managing ideology is pursuing technology innovation and creating the top brand in the alloy field. We persist in Quality - the foundation of the survival. It is our forever ideology to serve you with full heart and soul. We committed to provide customers all over the world with high-quality, competitive products and perfect service.

Our products, such us nichrome wire, nichrome strip, fecral wire, fecral strip, thermocouple wire, nickel wire, nickel strip have been exported to Europe, USA, India, Southest Asia, South America,etc.

We are willing to establish strong and long-time partnership with our customers

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