Fe-Ni-Co Ceramic Sealing Alloys | 4J33 & 4J34 for 95% Alumina

Description

Fe-Ni-Co sealing alloys (4J33, 4J34) offer CTE closely matched to 95% Al₂O₃ ceramic. Ideal for vacuum electronics, semiconductor packaging, and medical/aerospace components. YB/T 5234-93 compliant, MTC EN 10204 3.1 available.

Fe-Ni-Co Ceramic Sealing Alloys for 95% Al₂O₃ Alumina

Hefei Ke Ningman New Energy Materials Technology Co., Ltd. supplies Fe-Ni-Co ceramic sealing alloys, including 4J33 and 4J34, for matched-expansion sealing with 95% Al₂O₃ alumina ceramic.

These controlled expansion alloys are designed for applications where the thermal expansion behavior of the metal must be compatible with ceramic components during high-temperature sealing and subsequent thermal cycling.

Fe-Ni-Co sealing alloys are widely considered for ceramic-to-metal seals, hermetic electronic packages, vacuum electronic devices, semiconductor components, electrical feedthroughs, aerospace equipment, medical components and other precision assemblies requiring controlled thermal expansion.

What Are Fe-Ni-Co Sealing Alloys?

Fe-Ni-Co sealing alloys are iron-nickel-cobalt controlled expansion alloys developed for joining metallic components with glass or ceramic materials.

The primary engineering objective is to control the difference in thermal expansion between the metal and the mating ceramic. When dissimilar materials are heated and cooled during a sealing process, differences in their coefficients of thermal expansion (CTE) can generate thermal stress at the interface.

An appropriately selected Fe-Ni-Co alloy helps reduce thermal mismatch and supports reliable ceramic-to-metal sealing.

For 4J33 and 4J34, the material is specifically used for matched sealing with 95% Al₂O₃ ceramic. Chinese precision-alloy references identify 4J33 and 4J34 as ceramic sealing alloys for this application.

4J33 and 4J34 Fe-Ni-Co Ceramic Sealing Alloys

Our Fe-Ni-Co ceramic sealing alloy range includes:

The exact thermal expansion characteristics should be evaluated over the actual sealing and operating temperature range. Material selection should consider the ceramic grade, CTE, sealing process, component geometry and required hermeticity.

4J33 Ceramic Sealing Alloy

4J33 is an Fe-Ni-Co controlled expansion alloy used primarily for matched sealing with 95% alumina ceramic.

It can be used in:

• Ceramic-to-metal seals

• Vacuum electronic devices

• Hermetic packages

• Electrical feedthroughs

• Electronic components

• Semiconductor-related components

• Precision ceramic assemblies

• High-vacuum equipment

4J33 is also commonly associated with Kovar-type ceramic sealing applications, but alloy designation, chemical composition and thermal expansion characteristics should be verified before treating one grade as a direct substitute for another.

4J34 Ceramic Sealing Alloy

4J34 is another Fe-Ni-Co ceramic sealing alloy intended for applications requiring controlled thermal expansion and compatibility with 95% Al₂O₃ ceramic.

Potential applications include:

• Ceramic-metal sealing

• Electronic packages

• Vacuum components

• Electrical feedthroughs

• Hermetic assemblies

• Precision instruments

• Aerospace components

• Medical and electronic equipment

The appropriate grade should be selected according to the required thermal expansion characteristics, ceramic material and sealing process.

Why Match Fe-Ni-Co Alloy with 95% Al₂O₃ Ceramic?

The most important consideration in ceramic-to-metal sealing is thermal expansion matching.

95% alumina is widely used as an electrical insulating ceramic in hermetic and high-temperature assemblies. Kovar-type Fe-Ni-Co alloys have long been used with alumina ceramic because their thermal expansion characteristics can be suitable for ceramic-metal sealing structures. Historical technical literature also documents Kovar with approximately 95% alumina ceramic in hermetic component construction.

During heating:

Metal expands + Ceramic expands

During cooling:

Metal contracts + Ceramic contracts

If the expansion difference is too large, excessive interfacial stress can contribute to:

• Ceramic cracking

• Interface separation

• Leakage

• Seal failure

• Dimensional distortion

• Reduced thermal-cycle reliability

Therefore, the goal is not simply to choose a metal with a “low CTE,” but to select a material whose thermal expansion behavior is appropriate for the specific ceramic and sealing temperature range.

What Is 95% Al₂O₃ Ceramic?

95% alumina ceramic is an aluminum-oxide-based engineering ceramic commonly used as an electrical insulator and structural component in electronic and vacuum applications.

In ceramic-to-metal assemblies, it can be combined with a controlled-expansion metal such as an Fe-Ni-Co alloy.

Typical applications include:

• Electrical insulators

• Hermetic feedthroughs

• Semiconductor packages

• Vacuum components

• High-voltage components

• Electronic packages

• Ceramic headers

• Ceramic-to-metal assemblies

The ceramic and metal should be evaluated as a complete sealing system rather than as independent materials.

How Does Ceramic-to-Metal Sealing Work?

A typical ceramic-to-metal sealing structure may involve:

Ceramic Preparation → Ceramic Metallization → Metal Component Preparation → Assembly → Brazing / Sealing → Cooling → Inspection → Hermeticity Testing

The metal alloy is selected according to the thermal expansion behavior of the ceramic.

For metallized alumina, the ceramic surface may be prepared with an appropriate metallization system before brazing to the Fe-Ni-Co alloy.

Published technical examples demonstrate the use of metallized 95% alumina ceramic with 4J33 Fe-Ni-Co alloy in brazing processes.

The exact metallization, brazing alloy and temperature profile should be determined by the finished component design and production process.

Fe-Ni-Co Sealing Alloys vs Kovar

Kovar is a widely recognized Fe-Ni-Co controlled expansion alloy used for glass-to-metal and ceramic-to-metal sealing.

However, Kovar should not automatically be treated as identical to every Fe-Ni-Co sealing alloy.

For engineering procurement, customers should compare:

• Chemical composition

• Coefficient of thermal expansion

• Temperature range

• Ceramic grade

• Sealing temperature

• Mechanical properties

• Material standard

• Product condition

4J33 is specifically associated with matched sealing to 95% Al₂O₃ ceramic in Chinese precision-alloy references, while Kovar is a broader commercial designation for a Fe-Ni-Co controlled-expansion alloy family.

For this reason, if your project specifies “Kovar,” the exact required standard and composition should be confirmed before material substitution.

Fe-Ni-Co Ceramic Sealing Alloy Applications

1. Semiconductor Packaging

Fe-Ni-Co controlled expansion alloys can be used in selected semiconductor and electronic packaging structures where metal-to-ceramic thermal compatibility is required.

Typical components may include:

• Ceramic packages

• Headers

• Feedthroughs

• Lead frames

• Hermetic housings

• Electronic connectors

2. Vacuum Electronics

Ceramic-to-metal seals are important in vacuum electronic equipment because the sealed interface must maintain structural integrity and low leakage under vacuum conditions.

Applications can include:

• Vacuum electronic devices

• Electron tubes

• High-voltage vacuum components

• Feedthrough assemblies

• Vacuum instrumentation

3. Hermetic Electronic Packages

Fe-Ni-Co alloys can be used in hermetic packaging where ceramic insulation and a metallic housing must be joined while controlling thermal stress.

4. Electrical Feedthroughs

Ceramic feedthroughs require reliable interfaces between electrical conductors, insulating ceramics and metallic structures.

A controlled-expansion Fe-Ni-Co alloy can serve as the metallic sealing component where its thermal expansion is compatible with the ceramic system.

5. Aerospace Components

Aerospace electronic and sensing systems may require materials capable of maintaining dimensional and sealing integrity across changing temperatures and demanding environmental conditions.

6. Medical and Precision Components

Hermetic electronic and sensor assemblies used in selected medical or precision applications may require ceramic-metal sealing and controlled thermal expansion.

Key Properties of Fe-Ni-Co Sealing Alloys

Depending on the grade and processing condition, important properties include:

• Controlled coefficient of thermal expansion

• Thermal expansion compatibility with alumina ceramic

• Dimensional stability

• Suitable mechanical strength

• Good formability for selected product forms

• Good compatibility with ceramic sealing processes

• Stable performance in hermetic assemblies

• Suitable electrical and thermal characteristics for specific applications

The actual CTE should always be specified with its measurement temperature range.

For precision sealing applications, engineers should evaluate the entire thermal expansion curve rather than relying on a single CTE value.

How to Select a Fe-Ni-Co Ceramic Sealing Alloy

Selecting the correct alloy should begin with the ceramic and sealing process.

Step 1: Identify the Ceramic

Specify the ceramic material, such as 95% Al₂O₃, and provide the ceramic manufacturer's grade whenever possible.

Step 2: Determine the Ceramic CTE

The coefficient of thermal expansion of the ceramic is one of the most important inputs for alloy selection.

Step 3: Define the Sealing Temperature

The metal and ceramic must remain compatible throughout the heating, sealing and cooling cycle.

Step 4: Select the Alloy Grade

For 95% alumina ceramic applications, 4J33 and 4J34 are potential Fe-Ni-Co sealing alloy grades.

Step 5: Define Hermeticity Requirements

For vacuum and electronic packages, specify the required leak rate, pressure environment and thermal cycling conditions.

Step 6: Define Product Form

Depending on the grade and production requirements, material can be supplied in forms such as:

• Sheet

• Strip

• Plate

• Wire

• Rod

• Bar

• Foil

• Coil

• Custom precision parts

Technical Data and Material Specifications

For production procurement, the material specification should include:

Where a customer requires specific CTE values, chemical composition or mechanical properties, the final values should be taken from the applicable material standard and the supplier's certified inspection data.

Manufacturing and Quality Control

For ceramic sealing alloys, quality control should cover both chemical composition and thermal expansion behavior.

A typical production process may include:

Raw Material Verification → Melting → Composition Control → Hot Working → Cold Working → Intermediate Annealing → Final Heat Treatment → Surface Finishing → Dimensional Inspection → Thermal Expansion Testing → Final Inspection

Important inspection items can include:

• Chemical composition

• CTE / thermal expansion

• Dimensional tolerance

• Surface quality

• Mechanical properties

• Hardness

• Microstructure

• Heat-treatment condition

• Material traceability

• Inspection certificate

For critical hermetic applications, the finished ceramic-metal assembly should additionally be evaluated using an appropriate leak-testing and thermal-cycling procedure.

YB/T 5234-93 and Material Documentation

4J33 and 4J34 are identified in Chinese precision-alloy references as ceramic sealing alloys under YB/T 5234-93, for matched sealing with 95% Al₂O₃ ceramic.

Our current product page states that 4J33 and 4J34 are supplied according to YB/T 5234-93 requirements and that EN 10204 3.1 material certificates (MTC) are available.

For international projects, customers should specify the required standard, inspection level and documentation before production so that the applicable material and certification requirements can be confirmed.

Available Product Forms

Depending on alloy grade, dimensions and production requirements, Fe-Ni-Co sealing alloys may be supplied as:

• Fe-Ni-Co alloy sheet

• Fe-Ni-Co alloy strip

• Fe-Ni-Co alloy plate

• Fe-Ni-Co alloy wire

• Fe-Ni-Co alloy rod

• Fe-Ni-Co alloy bar

• Fe-Ni-Co alloy foil

Custom-machined sealing components

Customized dimensions, tolerances and material conditions can be discussed according to engineering drawings and purchasing specifications.

Why Choose Our Fe-Ni-Co Sealing Alloys?

Hefei Ke Ningman New Energy Materials Technology Co., Ltd. provides specialty alloy materials for industrial and precision applications.

For Fe-Ni-Co ceramic sealing alloy projects, we can support customers with:

• 4J33 and 4J34 material supply

• Alloy grade selection

• CTE-based material evaluation

• 95% alumina ceramic matching requirements

• Customized dimensions

• Product form selection

• Technical specification review

• Quality inspection

• Material certificates

• International B2B supply

If your application involves 95% Al₂O₃ ceramic-to-metal sealing, provide the ceramic grade, required CTE, sealing temperature, product dimensions, alloy grade and application requirements.

Our technical team can evaluate the appropriate Fe-Ni-Co sealing alloy specification.

Fe-Ni-Co Sealing Alloy FAQ

What are Fe-Ni-Co sealing alloys?

Fe-Ni-Co sealing alloys are controlled expansion alloys used to join metal components with glass or ceramic materials while controlling thermal expansion mismatch.

What is 4J33 alloy?

4J33 is an Fe-Ni-Co ceramic sealing alloy commonly used for matched sealing with 95% Al₂O₃ alumina ceramic.

What is 4J34 alloy?

4J34 is an Fe-Ni-Co controlled expansion alloy used for ceramic sealing applications where thermal expansion compatibility is required.

What ceramic is 4J33 matched with?

4J33 is commonly specified for matched sealing with 95% Al₂O₃ ceramic. The exact ceramic grade and CTE should be confirmed before production.

Is 4J33 the same as Kovar?

4J33 and Kovar are both Fe-Ni-Co controlled expansion alloys, but the terms should not automatically be treated as interchangeable. The exact composition, standard and CTE should be compared before substitution.

What is ceramic-to-metal sealing?

Ceramic-to-metal sealing is a joining process in which a ceramic component is hermetically or mechanically joined to a metal component while controlling thermal expansion mismatch between the two materials.

What is 95% alumina ceramic used for?

95% alumina ceramic is commonly used as an electrical insulating and structural ceramic in electronic, vacuum and high-temperature assemblies.

Why is CTE important in ceramic sealing?

CTE determines how much a material expands or contracts as temperature changes. A large mismatch between ceramic and metal can generate thermal stress during heating and cooling.

Can 4J33 and 4J34 be customized?

Customized dimensions, product forms, tolerances and material conditions may be available depending on the alloy grade and production requirements.

Can you provide MTC?

The current product page states that EN 10204 3.1 material certificates are available. The required certification and inspection documentation should be confirmed when placing the order.

Request a Quote for 4J33 / 4J34 Fe-Ni-Co Sealing Alloys

Looking for 4J33 or 4J34 Fe-Ni-Co ceramic sealing alloys for 95% Al₂O₃ alumina?

Send us:

• Alloy grade

• Ceramic grade

• Required CTE

• Sealing temperature

• Operating temperature

• Product form

• Dimensions and tolerances

• Quantity

• Application

• Required material standard

• Inspection certificate requirements

We can review your requirements and provide a suitable Fe-Ni-Co ceramic sealing alloy solution and quotation.