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Application of Cu70Ni30 Alloy in Aviation Cable Shielding – Interference Resistance and Corrosion Resistance, Surpassing the Limits of Pure Metal Shielding

Aerospace cables are the core carriers for data transmission and power supply in various aircraft systems (avionics, navigation, and communication). The shielding layer, as the cable's "protective barrier," must possess excellent electromagnetic shielding, corrosion resistance, flexibility, and mechanical strength to withstand the effects of complex environments such as high-altitude electromagnetic interference, salt spray, humidity, and extreme temperatures, ensuring the stability and security of cable signal transmission and preventing system failures caused by signal interference. Pure metals, as traditional cable shielding materials, either offer good shielding but poor corrosion resistance, or good flexibility but insufficient shielding effect, making them unsuitable for the stringent requirements of aviation cables. Copper 70-Ni 30 alloy (Cu70-Ni30, 70% copper and 30% nickel by mass), with its excellent electromagnetic shielding, corrosion resistance, and flexibility, has become the preferred material for high-end aviation cable shielding, driving the upgrade of aviation cable technology towards higher reliability and interference resistance.

In aviation cable shielding applications, the performance shortcomings of various pure metals are very prominent, making it difficult to meet the requirements for interference resistance and long-term stable service. Pure copper is a commonly used pure metal material for traditional cable shielding layers. It offers excellent electromagnetic shielding (shielding effectiveness exceeding 80dB), good processing performance, and flexibility, allowing for the fabrication of thin-walled shielding layers at a controllable cost. However, pure copper lacks corrosion resistance and is prone to oxidation in high-altitude salt spray and humid environments, forming verdigris. This leads to shielding layer damage and reduced shielding effectiveness. In actual tests, the average lifespan of pure copper shielding layers in aviation environments is only 2000 hours. Furthermore, pure copper has poor abrasion resistance and is easily worn, limiting its use to shielding layers for low- to mid-range aviation cables.

Pure aluminum has low density and good flexibility, offering advantages in lightweight design and good electromagnetic shielding (shielding effectiveness up to 60dB). It has been attempted for use in lightweight cable shielding layers. However, pure aluminum has poor corrosion resistance and easily forms a loose oxide film in high-altitude environments, leading to shielding layer detachment and rapid attenuation of shielding effectiveness. Furthermore, pure aluminum has low strength and poor wear resistance, making it easily stretched and damaged, limiting its application to low-temperature, low-interference auxiliary cables. Pure steel, on the other hand, has excellent electromagnetic shielding (shielding effectiveness up to 85dB), high strength, and good wear resistance. However, pure steel has poor flexibility, making it difficult to fabricate thin-walled shielding layers. It also has extremely poor corrosion resistance, easily rusting in humid and salt spray environments, leading to damage to the cable insulation layer. Therefore, it can only be used for shielding layers of fixed, thick cables and cannot be used for flexible cables requiring bending.

Pure titanium has excellent corrosion resistance, but poor electromagnetic shielding (shielding effectiveness of only 40dB), making it unable to withstand strong electromagnetic interference at high altitudes. It is also difficult and expensive to process, has poor flexibility, and is difficult to manufacture into flexible shielding layers, limiting its use to auxiliary shielding structures in niche high-end corrosion-resistant cables. Pure nickel offers good electromagnetic shielding (shielding effectiveness up to 70dB) and excellent corrosion resistance, but its poor flexibility and processing performance make it difficult to manufacture thin-walled flexible shielding layers. Furthermore, its high cost—more than twice that of Cu70Ni30 Alloy—makes large-scale application difficult. Pure silver offers the best electromagnetic shielding (shielding effectiveness up to 90dB), but its extremely high cost, poor corrosion resistance, and tendency to oxidize and blacken limit its use to niche high-end precision cables, preventing widespread application.

Compared to various pure metals, the core advantage of the Cu70Ni30 Alloy lies in its perfect balance of electromagnetic shielding, corrosion resistance, flexibility, and mechanical strength. Its 70% copper and 30% nickel mass ratio is precisely tailored to the requirements of cable shielding layers—copper ensures the alloy's excellent electromagnetic shielding and flexibility, while nickel significantly enhances its corrosion resistance and wear resistance. The synergistic effect of these two elements compensates for the shortcomings of pure metals, which excel in a single property but lack comprehensive performance. The alloy's electromagnetic shielding effectiveness can reach over 85dB, comparable to pure steel and far exceeding that of pure aluminum and pure titanium. It can effectively resist strong electromagnetic interference at high altitudes, ensuring the stability of cable signal transmission and preventing signal distortion or interference.

In terms of corrosion resistance, the Cu70Ni30 Alloy forms a dense oxide film on its surface, effectively resisting the erosion of corrosive media such as high-altitude salt spray, humidity, and fuel vapor. In actual tests, after immersion in a simulated aviation environment for 3000 hours, the corrosion rate of this alloy shielding layer was only 0.01 mm/a, only 1/30th that of pure copper and 1/50th that of pure steel, with no oxidation or damage. The shielding effectiveness attenuation rate was controlled within 5%, far superior to pure metal shielding layers, and its service life was 6-8 times longer than that of pure copper shielding layers. Regarding flexibility and processing performance, this alloy possesses excellent flexibility, with a bending radius only 5 times its own diameter, far superior to pure steel (10 times) and pure nickel (8 times). It can adapt to the bending and laying requirements of aviation cables and can be manufactured into thin-walled shielding layers (thickness controllable between 0.05-0.1 mm) through rolling, drawing, and other processes. This results in high processing precision, a smooth surface, and tight adhesion to the cable insulation layer without gaps. Furthermore, the Cu70Ni30 Alloy possesses excellent mechanical strength, with a tensile strength of 450-550 MPa and a yield strength ≥200 MPa. It exhibits good wear resistance, is not easily stretched or damaged, and can withstand the mechanical impacts during cable laying and use, preventing signal interference caused by shielding layer damage. This alloy has a density of 8.9 g/cm³, which is 12% lighter than pure steel and 25% lighter than pure copper. While maintaining shielding performance, it effectively reduces the overall weight of the cable, aligning with the trend towards lightweighting in aviation. It is estimated that aviation cables using the Cu70Ni30 Alloy shielding layer are more than 20% lighter than cables with pure copper shielding, significantly reducing the load on aircraft.

Currently, the Cu70Ni30 Alloy has been applied to high-end avionics and navigation cables for aircraft such as the Boeing 787, Airbus A350, and domestically produced C919 and J-20 fighter jets. Domestic mass production of aviation-grade Cu70Ni30 Alloy shielding tapes and wires has been achieved, with product thickness tolerance controlled within ±0.005 mm and a 100% shielding effectiveness compliance rate. However, there is still room for development: First, the shielding effectiveness under high-frequency signals can be further improved to adapt to more advanced avionics systems; second, the welding performance of thin-walled shielding layers needs to be optimized to ensure the continuity of the shielding layer. In the future, by adding trace amounts of silver and gold to improve high-frequency shielding effectiveness and improving welding processes, Cu70Ni30 Alloy is expected to become the dominant material for aviation cable shielding layers, completely replacing pure metals and driving the development of aviation cables towards high anti-interference and high reliability.

AlloyHit specializes in producing Cu70Ni30 products in various specifications, such as Cu70Ni30 Sheets, Cu70Ni30 Rods, Cu70Ni30 Wires and Cu70Ni30 Tubes.