Home > Low Expansion Alloy >

4J28 Rod / Bar | Kovar Alloy Rods for Glass-to-Metal Sealing Applications

Product Categories

Low Expansion Alloy [48]
Soft Magnetic Alloy [19]
Elastic Alloy [10]
Thermal Bimetal [11]
Welding Wire [26]
Thermal Spray Wire [27]
Nichrome Alloy [55]
Pure Nickel [24]
Copper Nickel Alloy [25]
Thermocouple Cable [43]
Monel Alloy [9]
Inconel Alloy [25]
Hastelloy Alloy [5]
High Temperature Alloy [24]
Nitinol Alloy [9]
To Header [21]
Others [3]

Huona (Shanghai) New Material Co., Ltd.

Trust Seal

Verified Supplier

Credit Check

Supplier Assessment

Contact Now

4J28 Rod / Bar | Kovar Alloy Rods for Glass-to-Metal Sealing Applications

Name: 4J28 Rod Bar Kovar Alloy Rods for GlasstoMetal Sealing Applications
Brand: HUONA
Price: 1 USD

Brand Name : HUONA

Model Number : Bar

Certification : ISO 9001, SGS, RoHS

Place of Origin : china

MOQ : 5kg

Price : negotiation

Payment Terms : T/T

Supply Ability : 1000kg a week

Delivery Time : 1 week

Packaging Details : Wooden case, steel strip bundling

Density : ~8.2 g/cm³

Thermal Expansion (20–400°C) : ~5.0 ×10⁻⁶/°C

Tensile Strength : ≥ 450 MPa

Working Temp : -196°C to 450°C

Diameter : 3 mm – 200 mm

Contact Now

Product Description

4J28 alloy rod is an iron-nickel-cobalt (Fe-Ni-Co) controlled expansion alloy specially designed for glass-to-metal and ceramic-to-metal sealing applications. It has a linear expansion coefficient that precisely matches hard glass and ceramics, ensuring reliable hermetic sealing.

With stable mechanical strength, excellent machinability, and outstanding sealing performance, 4J28 rods are widely used in electronic packaging, vacuum devices, semiconductor components, and aerospace instruments.

4J28 Rod / Bar | Kovar Alloy Rods for Glass-to-Metal Sealing Applications

Key Features

Fe-Ni-Co alloy with controlled thermal expansion
Excellent sealing performance with glass and ceramics
Stable mechanical strength at various temperatures
Easy machining and surface treatment
Reliable long-term hermeticity
Available in rods, wires, sheets, and customized forms

Typical Applications

Glass-to-metal hermetic sealing
Electronic packaging components
Vacuum tubes and light bulbs
Semiconductor packaging bases
Aerospace and defense devices
Sensor housings and feedthroughs

Chemical Composition (%)

Element	Content
Fe	Balance
Ni	~28%
Co	~18%
Minor Elements	Mn, Si, C, etc.

Physical and Performance Properties

Property	Typical Value
Density	~8.2 g/cm³
Thermal Expansion (20–400°C)	~5.0 ×10⁻⁶/°C
Tensile Strength	≥ 450 MPa
Hardness	~HB 140–170
Working Temp	-196°C to 450°C
Standard	GB/T, ASTM, IEC

Available Specifications

Item	Range
Diameter	3 mm – 200 mm
Length	≤ 6000 mm
Tolerance	As per ASTM / GB standard
Surface	Bright / Polished / Black
Packaging	Wooden case, steel strip bundling
Certification	ISO 9001, SGS, RoHS
Origin	China (OEM/ODM service available)

Packaging & Shipping:

Packaging:
Plastic spools, vacuum bags, anti-rust wrapping, and customized labels upon request
Shipping Methods:
Air freight, sea freight, express delivery
Lead Time:
7–15 working days based on order quantity

4J28 Rod / Bar | Kovar Alloy Rods for Glass-to-Metal Sealing Applications

Product Tags: