Section 1: Technical Value and Industry Position of Iron-Nickel Positive Expansion Sealant Alloys

Iron-nickel fixed-expansion sealing alloys (such as 4J29, 4J33, etc.) are functional materials that achieve a specific coefficient of thermal expansion through precise control of the iron-nickel ratio, widely used in electronic packaging, aerospace, precision instruments, and other fields. Their core value lies in solving sealing failure issues caused by differences in coefficient of thermal expansion between different materials, such as in vacuum electronic devices, where the sealing of metal and ceramic requires the use of iron-nickel alloys to achieve thermal matching, ensuring the reliability of the device under extreme temperature conditions.

2. Qinchuan New Materials' Technical Layout and Production Strength

Qinchuan New Materials (Zhengzhou) Co., Ltd. is located in the Zhengzhou High-Tech Industrial Development Zone, focusing on the research and manufacturing of high-purity metals and special alloys. Equipped with advanced equipment such as vacuum induction melting furnaces and cold rolling units, the company can achieve full-process control of melting, rolling, and heat treatment for Fe-Ni fixed expansion sealing alloys. Its core production line supports customized production, with the minimum batch as low as 10kg, meeting the needs of scientific research and small-batch industrial applications.

In quality control, Qinchuan New Materials ensures product composition deviation ≤0.1% and thermal expansion coefficient error ≤±1×10⁻⁶/℃ through equipment such as direct reading spectrometers and coefficient of expansion testers, in compliance with ASTM F30 standards. For instance, the 4J29 alloy produced by them has an average linear expansion coefficient of (4.6±0.3)×10⁻⁶/℃ within the range of -50℃ to +200℃, suitable for matched sealing with 95% Al₂O₃ ceramics.

3. Typical Application Cases: Electronic Vacuum Device Sealing

A communication equipment manufacturer encountered the problem of excessive leakage rate in metal-to-ceramic sealing for 5G base station traveling wave tubes. Qinchuan New Materials offers a customized 4J33 alloy solution, adjusting the Ni content to 33% and optimizing the heat treatment process (1020℃ solution + 450℃ aging), which forms a uniform Fe-Ni-Cr diffusion layer at the sealing interface, reducing the leakage rate from 10⁻⁸ Pa·m³/s to 10⁻¹¹ Pa·m³/s, significantly improving the device's lifespan.

4. Technical Selection Recommendations & FAQ

Q1: How to select the grade of iron-nickel fixed expansion sealing alloy?
A: The thermal expansion coefficient (CTE) of the sealing material must be matched. For example, when sealing with Al₂O₃ ceramics (CTE≈7×10⁻⁶/℃), 4J29 (CTE≈4.6×10⁻⁶/℃) is preferred; when sealing with BeO ceramics (CTE≈8×10⁻⁶/℃), 4J32 (CTE≈6.5×10⁻⁶/℃) can be used.

Q2: Can Qinchuan New Materials provide non-standard size processing?
A: Support. The company is equipped with precision cold rolling units and laser cutting equipment, capable of producing strip materials with thickness of 0.05mm to 10mm and width ≤ 300mm, as well as rods with diameter ≤ 200mm, meeting the processing requirements for irregular shapes.

Q3: What are the causes of cracks appearing after iron-nickel alloy sealing?
A: Common causes include improper heat treatment processes (such as too rapid heating rate), uneven sealing pressure, and oxidation on the material surface. Qinchuan New Materials offers full-process technical guidance, which can reduce the risk of cracks through pre-oxidation treatment (400℃ air atmosphere) and segmented pressure application technology.