4J43 Dumet Core Alloy Manufacturer | 42% Ni-Fe Wire Core

Description

4J43 Dumet Core Alloy is a controlled expansion alloy for copper-clad wire (Dumet wire) manufacturing. Ideal for glass-to-metal seals in semiconductor packaging, lamp bulbs, and vacuum electronics. YB/T 5236-93 compliant.

4J43 Dumet Core Alloy | 42% Nickel-Iron Core for Copper-Clad Wire

4J43 Dumet core alloy is a controlled-expansion iron-nickel alloy used as the core material for copper-clad Dumet wire and other glass-to-metal sealing applications.

With a nominal nickel content in the range of approximately 41–43%, 4J43 provides the low and controlled thermal expansion required for the core of Dumet wire. When combined with a copper sheath, the composite wire can provide a thermal expansion behavior suitable for sealing through selected soft glass systems.

Hefei Ke Ningman New Energy Materials Technology Co., Ltd. supplies 4J43 nickel-iron alloy in wire, rod and other customized forms for Dumet wire manufacturing, electrical lead applications and precision glass-to-metal sealing.

4J43 Dumet Core Alloy at a Glance

Chemical composition, thermal expansion characteristics and product condition should be confirmed against the applicable material specification.

What Is 4J43 Alloy?

4J43 is a 42% nickel-iron controlled expansion alloy commonly used as a core material for Dumet wire.

The alloy belongs to the iron-nickel precision expansion alloy family. Its controlled thermal expansion characteristics make it suitable for applications where the metal must be thermally compatible with glass during a heating and cooling cycle.

Published material data list approximately:

• Ni: 41–43%

• Mn: 0.75–1.25%

• Si: ≤0.30%

• C: ≤0.20%

• P: ≤0.02%

• S: ≤0.02%

• Fe: Balance

The exact chemical composition should be controlled according to the applicable specification and the customer's purchasing requirements.

4J43 as Dumet Wire Core Material

The most important application of 4J43 is its use as the nickel-iron core of Dumet wire.

Dumet wire is not simply 4J43 wire.

Instead, it is a composite conductor consisting of:

4J43 Fe-Ni Core → Copper Cladding → Surface Oxide / Borate Treatment → Dumet Wire

The low-expansion Fe-Ni core controls the basic thermal expansion behavior, while the copper sheath provides electrical conductivity and contributes to the radial expansion behavior required for glass sealing.

This combination allows Dumet wire to provide a practical balance between:

• Controlled thermal expansion

• Electrical conductivity

• Glass wettability

• Mechanical strength

• Hermetic sealing performance

ASTM F29 defines Dumet as round copper-coated approximately 42% nickel-iron wire intended primarily for sealing to soft glass. The standard also addresses core composition, copper coating, oxide coating, thermal expansion, dimensions and workmanship.

How 4J43 Works in Dumet Wire

The performance of Dumet wire depends on the interaction between the Fe-Ni core and copper sheath.

Step 1 — 4J43 Provides the Controlled-Expansion Core

The 4J43 core has a much lower thermal expansion than copper.

Step 2 — Copper Provides Electrical Conductivity

Copper has high electrical and thermal conductivity, making it suitable as the conductive outer layer.

Step 3 — Copper and Core Work as a Composite

The relative dimensions and material properties of the core and copper sheath influence the overall radial thermal expansion behavior of the Dumet wire.

Step 4 — Surface Treatment Supports Glass Sealing

Dumet wire can receive an oxide or borate-based surface treatment to improve interaction with molten glass during sealing.

Step 5 — The Composite Wire Forms the Glass Seal

During sealing, the wire and glass are heated and subsequently cooled under controlled conditions.

The goal is to obtain a stable interface with controlled residual stress.

4J43 Thermal Expansion

Thermal expansion is the key reason 4J43 is used as a Dumet core material.

A glass-to-metal seal must accommodate thermal expansion during:

Heating → Glass Softening → Sealing → Cooling → Final Operating Condition

If the metal and glass have excessive thermal expansion mismatch, tensile stress can develop in the glass during cooling.

This can result in:

• Glass cracking

• Seal failure

• Leakage

• Loss of hermeticity

• Interface separation

• Reduced thermal-cycle reliability

The 4J43 core therefore provides the controlled expansion foundation for the Dumet composite.

For final Dumet-wire design, however, engineers should evaluate the thermal expansion of the complete copper-clad wire, not only the CTE of the 4J43 core.

Published Dumet specifications and technical references evaluate thermal expansion over defined temperature ranges and material conditions.

4J43 vs Dumet Wire

4J43 and Dumet wire are related but not identical.

This distinction is important when specifying materials for manufacturing.

If you are purchasing material to manufacture Dumet wire, you may require 4J43 core alloy.

If you are purchasing the finished conductor for glass sealing, you may instead require Dumet wire manufactured to ASTM F29 or another applicable specification.

4J43 for Soft Glass Sealing

4J43 is primarily associated with the core material used in Dumet wire for sealing through suitable soft glass.

The complete sealing system depends on:

• 4J43 core composition

• Copper sheath thickness

• Finished wire diameter

• Radial CTE

• Axial CTE

• Surface oxidation

• Borate coating

• Glass composition

• Glass CTE

• Sealing temperature

• Heating rate

• Cooling rate

The exact glass should therefore be selected together with the complete Dumet wire specification.

Dumet wire is widely associated with sealing copper electrical leads through soda-lime and lead glass systems.

4J43 Copper-Clad Wire Core

The copper-clad construction is fundamental to Dumet wire.

A simplified cross-section is:

Copper Sheath

↓

4J43 Fe-Ni Core

↓

Copper Sheath

The core provides controlled thermal expansion and mechanical support, while copper provides electrical conductivity.

The relative proportion of core and copper must be controlled because changing the copper sheath thickness can affect the thermal and mechanical behavior of the finished wire.

For this reason, Dumet wire manufacturers need consistent:

• Core diameter

• Copper thickness

• Core-to-sheath ratio

• Finished diameter

• Surface condition

• Oxide coating

• Drawing condition

4J43 Core Alloy for Glass-to-Metal Sealing

Glass-to-metal sealing requires a controlled relationship between:

Metal CTE ↔ Glass CTE ↔ Sealing Temperature ↔ Cooling Rate

The metal should be selected based on the actual glass system.

For Dumet applications, the design objective is not simply to match the axial expansion of the metal and glass.

The composite structure is designed so that the radial expansion behavior of the copper-clad wire is appropriate for the glass sealing system.

Technical descriptions of Dumet wire explain that the copper sheath and low-expansion Fe-Ni core work together to produce a radial thermal expansion compatible with soft glass while limiting harmful tensile stress at the interface.

4J43 Applications

1. Dumet Wire Manufacturing

The primary application is the production of copper-clad Dumet wire.

4J43 provides the controlled-expansion Fe-Ni core required for the composite conductor.

2. Glass-Sealed Electrical Leads

Dumet wire is commonly used as an electrical lead passing through a glass seal.

Applications may include:

• Lamps

• Diodes

• Thermistors

• Vacuum electronic devices

• Glass-sealed electrical components

Dumet wire is specifically used in glass-sealed thermistors and similar components because the Fe-Ni core helps bring the thermal expansion behavior closer to the glass system.

3. Lighting Components

Dumet wire has historically been used for electrical leads in lamps and other glass-enclosed lighting components.

4. Electronic Components

Dumet-based glass-to-metal sealing can be used for selected electronic components requiring reliable electrical feedthroughs.

5. Hermetic Electrical Feedthroughs

Dumet wire can be used where an electrical conductor must pass through a glass barrier while maintaining a reliable seal.

6. Vacuum Electronic Components

Selected vacuum devices use Dumet-type glass-to-metal seals for electrical lead-through structures.

4J43 Chemical Composition

A representative 4J43 composition is:

The composition should be confirmed against the applicable 4J43 material standard and the customer's purchasing specification. Published reference data identify 4J43 as an approximately 42% nickel-iron controlled expansion alloy.

4J43 Product Forms

4J43 can be supplied according to the requirements of the intended manufacturing process.

Potential product forms include:

• 4J43 wire

• 4J43 rod

• 4J43 bar

• Precision-drawn wire

• Core wire for Dumet production

• Customized lengths

• Customized diameters

For Dumet-wire manufacturing, important parameters may include:

• Core diameter

• Diameter tolerance

• Straightness

• Surface condition

• Mechanical properties

• Chemical composition

• Thermal expansion characteristics

• Batch consistency

4J43 Manufacturing Process

A typical 4J43 precision-alloy manufacturing route may include:

Raw Material Preparation

Selected Fe, Ni and alloying materials are verified before melting.

Controlled Melting

The alloy is melted under controlled conditions to achieve the required composition.

Casting

The molten alloy is cast into an appropriate intermediate form.

Homogenization

Thermal treatment may be used to improve chemical and structural uniformity.

Hot Working

The alloy is processed into intermediate wire or rod dimensions.

Cold Drawing

Precision drawing is used to achieve the required core diameter and dimensional tolerance.

Annealing

Intermediate or final annealing may be applied to control hardness, residual stress and workability.

Surface Treatment

The surface is cleaned and finished according to the requirements of the intended Dumet manufacturing process.

Final Inspection

Finished material is inspected for chemical composition, dimensions, surface quality and other agreed specifications.

Dumet Wire Manufacturing with 4J43 Core

When 4J43 is used as the core material for Dumet wire, the manufacturing process typically continues beyond the production of the Fe-Ni core.

A simplified Dumet production route is:

4J43 Core Wire

↓

Copper Cladding

↓

Bonding / Welding

↓

Drawing

↓

Diameter Control

↓

Surface Treatment

↓

Oxidation / Borating

↓

Inspection

↓

Finished Dumet Wire

The exact production method depends on the customer's Dumet specification.

Industry technical references describe copper cladding, drawing and surface treatment as key stages in producing Dumet wire. Surface treatment may involve oxidation, borating or nickel plating depending on the application.

4J43 Quality Control

For Dumet core applications, material consistency is critical.

Quality control can include:

Chemical Composition

Verify:

• Ni

• Mn

• Si

• C

• P

• S

• Fe

Dimensional Inspection

Measure:

• Diameter

• Diameter tolerance

• Ovality

• Length

• Straightness

Surface Inspection

Check for:

• Cracks

• Scratches

• Oxide defects

• Pitting

• Surface contamination

• Drawing defects

Thermal Expansion Testing

The thermal expansion characteristics can be evaluated over the required temperature range.

Mechanical Testing

• Where specified:

• Tensile strength

• Elongation

• Hardness

Metallographic Inspection

Microstructural inspection can be used when required by the specification.

Material Traceability

Production batches can be linked to inspection records and material certificates.

ASTM F29 includes thermal expansion, copper analysis, metallography, dimensional and surface-related requirements for finished Dumet wire, illustrating the importance of controlling both the core and the finished composite conductor.

4J43 vs 4J42

4J43 and 4J42 are both Fe-Ni controlled expansion alloys, but they should not be treated as automatically interchangeable.

The correct material should be selected according to the customer's specification, glass system and required thermal expansion behavior.

4J43 vs 4J29 Kovar

4J43 and 4J29 are fundamentally different alloy systems.

4J29/Kovar should therefore not be substituted for 4J43 simply because both are controlled-expansion sealing alloys.

4J43 Material Standards and Specifications

When purchasing 4J43 for Dumet-core applications, the specification should clearly identify:

• Alloy designation

• Chemical composition

• Product form

• Diameter

• Dimensional tolerance

• Thermal expansion requirement

• Heat-treatment condition

• Surface condition

• Mechanical properties

• Inspection requirements

• Certification requirements

For finished Dumet wire, ASTM F29 is an important international reference because it specifically covers copper-coated approximately 42% nickel-iron wire intended primarily for soft-glass sealing.

The finished Dumet wire specification should not automatically be applied to the bare 4J43 core material. Core material and finished composite wire should be specified separately.

How to Select 4J43 Dumet Core Alloy

Before purchasing 4J43 core material, manufacturers should confirm:

1. Finished Dumet Wire Diameter

The final wire diameter determines the required core dimensions.

2. Copper Sheath Ratio

The copper-to-core ratio affects electrical and thermal performance.

3. Glass Grade

Provide the exact glass grade whenever possible.

4. Glass CTE

The glass thermal expansion coefficient is essential for sealing design.

5. Sealing Temperature

Specify the actual sealing temperature and thermal cycle.

6. Core Diameter

The required 4J43 core diameter should be specified before copper cladding.

7. Surface Condition

Specify whether the core requires bright, cleaned, annealed or another surface condition.

8. Mechanical Properties

Specify tensile strength, elongation or hardness if required.

9. Certification

Specify whether you require:

• Material certificate

• Chemical analysis

• Thermal expansion report

• Mechanical test report

• Inspection report

• Batch traceability

Why Choose 4J43 from Greenergy Materials?

Hefei Ke Ningman New Energy Materials Technology Co., Ltd. supplies precision special alloys for industrial applications.

For 4J43 Dumet-core projects, we can support customers with:

• 4J43 core alloy

• Precision wire supply

• Customized diameter

• Customized dimensions

• Material specification review

• Chemical composition control

• Thermal expansion requirements

• Batch traceability

• Material certification

• Export packaging

• Technical support for customized projects

For a new Dumet-wire project, provide the finished wire diameter, core diameter, copper ratio, glass grade, sealing temperature and required material standard.

4J43 Dumet Core Alloy FAQ

What is 4J43 alloy?

4J43 is an Fe-Ni controlled expansion alloy containing approximately 41–43% nickel. It is widely used as a core material for Dumet wire and other precision sealing applications.

What is 4J43 used for?

The main application of 4J43 is as the nickel-iron core of copper-clad Dumet wire used for soft glass-to-metal sealing.

Is 4J43 a Dumet wire?

No. 4J43 is the Fe-Ni core alloy. Dumet wire is a copper-clad composite conductor incorporating a nickel-iron core.

Why is 4J43 used as a Dumet core?

4J43 provides controlled thermal expansion and mechanical support, while the copper sheath provides high electrical conductivity and contributes to the thermal expansion behavior of the finished Dumet wire.

What is the nickel content of 4J43?

Published material data indicate a nickel content of approximately 41–43%. Exact limits should be confirmed against the applicable specification.

What is the difference between 4J43 and Dumet wire?

4J43 is a single Fe-Ni alloy used as the core. Dumet wire is a composite wire consisting of a nickel-iron core and copper sheath, generally designed for soft-glass sealing.

Is 4J43 suitable for soft glass sealing?

4J43 is commonly used as the core material of Dumet wire intended for soft glass sealing. The finished wire and glass system must be evaluated together.

What standard covers Dumet wire?

ASTM F29 covers round copper-coated approximately 42% nickel-iron wire, commonly known as Dumet, intended primarily for sealing to soft glass.

Can 4J43 be supplied as wire?

Yes. 4J43 can be supplied as precision wire and other forms according to dimensional and application requirements.

Can you supply 4J43 for Dumet wire manufacturing?

Yes. 4J43 can be supplied as core material for manufacturers producing copper-clad Dumet wire.

Can 4J43 dimensions be customized?

Yes. Core diameter, wire dimensions, tolerances, heat-treatment condition and other requirements can be discussed according to the production specification.

Can you provide a material certificate?

Material certificates and inspection documentation can be provided according to the agreed specification and order requirements.

Request a Quote for 4J43 Dumet Core Alloy

Looking for a reliable 4J43 Dumet core alloy manufacturer or supplier?

Please provide:

• 4J43 specification

• Core wire diameter

• Finished Dumet wire diameter

• Copper sheath ratio

• Glass grade

• Glass CTE

• Sealing temperature

• Required thermal expansion range

• Product quantity

• Dimensional tolerance

• Surface condition

• Material certificate requirements

Hefei Ke Ningman New Energy Materials Technology Co., Ltd. can review your requirements and provide 4J43 Fe-Ni core alloy for Dumet wire and precision glass-to-metal sealing applications.

Request a quotation for 4J43 Dumet core alloy today.