I. Technical Background: The Core Value of Iron-Nickel Positive Expansion Sealing Alloy

Iron-nickel fixed expansion sealing alloys are a type of special functional materials that achieve matching thermal expansion coefficients with glass/ceramics through precise control of nickel content, widely used in electrical vacuum devices, semiconductor packaging, aerospace sensors, and other fields. Their core advantage lies in solving the problem of cracking at the sealing interface caused by the difference in thermal expansion coefficients between metallic and non-metallic materials, ensuring long-term reliability of the equipment under extreme temperature environments.

Chapter II: Qinchuan New Materials' Technical Layout: Full Chain Capabilities from Research and Development to Mass Production

1. R&D Platform: An interdisciplinary innovative system
Qinchuan New Materials, leveraging the区位 advantage of Zhengzhou High-Tech Industrial Development Zone, has established a multidisciplinary research and development team with materials science as the core, integrating metallurgical engineering, heat treatment technology, and precision machining. Its technology center is equipped with high-precision instruments such as Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS), and Coefficient of Thermal Expansion Tester, enabling a full-process closed-loop control from composition design to performance verification.

2. Process Breakthrough: Vacuum Melting and Directed Solidification Technology
In response to the stringent purity requirements for iron-nickel superalloys, Qinchuan employs a dual process of vacuum induction melting (VIM) + electroslag remelting (ESR), controlling oxygen content to ≤15ppm and nitrogen content to ≤10ppm. Through directional solidification technology, castings with uniform grain orientation can be produced, significantly enhancing the material's anti-creep performance at high temperatures. For instance, the developed K418 alloy achieves a tensile strength of 220MPa at 900℃, surpassing the international level of similar products.

3. Parameter Control: Precise Adjustment of Coefficient of Thermal Expansion
By adjusting the nickel content (42%-44%) and trace element ratios, Qinchuan has achieved precise matching of the alloy's coefficient of thermal expansion within the range of (9.4-11.5)×10⁻⁶/℃。Taking the 4J44 alloy as an example, its average expansion coefficient is 11.2×10⁻⁶/℃ within the temperature range of 20-400℃, which is highly consistent with the expansion coefficient of DM-308 soft glass, capable of withstanding over 300 thermal cycles without leakage.

Chapter 3: Application Cases: Reliable Sealing Solutions for High-End Equipment

1. Case 1: Turbine Blade Sealing for Aviation Engines
The turbine blades of a certain type of aviation engine need to operate at a long-term high temperature of 1200°C. Traditional nickel-based alloys fail due to mismatched thermal expansion coefficients. The 4J50 alloy provided by Qinchuan, through co-sintering with ceramic matrix composites (CMC), achieves zero defects at the sealing interface. After 1000 hours of high-temperature testing, the leakage rate is ≤1×10⁻¹¹ Pa·m³/s, meeting the military standard GJB 548B-2005.

2. Case 2: Semiconductor Package Lead Frame
In the 5G communication chip packaging, the 4J29 alloy ( Kovar alloy) developed by Qinchuan, combined with the active metal brazing (AMB) process of alumina ceramic, solves the fatigue problem of the traditional copper frame due to the difference in coefficient of thermal expansion. Measured results show that the contact resistance change rate of its packaged devices after 1000 thermal cycles from -55℃ to 150℃ is ≤3%, significantly better than the industry average level.

3. Case 3: Medical CT Detector Components
In response to the stringent requirements for vacuum sealing in medical CT equipment, Qinchuan employs a matching sealing solution of 4J33 alloy and quartz glass. By pre-oxidation treatment, a dense oxide film is formed on the alloy surface, ensuring stable airtightness under temperature variations from -40℃ to 80℃. This solution has been applied by several leading medical equipment manufacturers, with a cumulative installed volume exceeding 100,000 units.

Four, Summary of Technical Advantages: Building Core Competitiveness in Three Dimensions

1. Material purity controlThrough the VIM+ESR double melting process, the content of impurity elements is reduced to 1/3 of the international standard, significantly improving the high-temperature stability of the material.
2. Heat Treatment System OptimizationDeveloped a graded solid solution + aging treatment process to control the γ' strengthening phase size between 50-100nm, balancing strength and toughness.
3. Full-process quality control systemFrom raw material inspection to finished product testing, implement 12 quality gate controls to ensure product batch stability ≥ 99.5%.

V. Future Outlook: Expand into Emerging Application Fields

With the rapid development of new energy vehicles and photovoltaic power generation industries, iron-nickel shape-memory alloys have shown great potential in solid-state battery encapsulation, high-temperature photovoltaic receivers, and other fields. Qinchuan New Materials is increasing its research and development investment in iron-nickel-cobalt alloys, nanocrystalline alloys, and other directions, planning to establish a complete product line covering the temperature range from -200℃ to 1500℃ by 2028, providing a more comprehensive material solution for high-end equipment manufacturing.