Preparation Process And Material Properties Of Silver Bimetal Rivet Contacts

The diversity of preparation processes is a critical factor in determining the ultimate performance of electrical contacts. Currently, mainstream preparation methods include powder metallurgy, internal oxidation, and thermal spraying. Among these, powder metallurgy-which involves processing immiscible materials into powders and sintering them into a mechanical mixture-serves as the foundational process for manufacturing refractory pseudo-alloys such as copper-tungsten and silver-tungsten. In contrast, traditional silver-cadmium electrical contacts are typically produced using the internal oxidation method. Although this material exhibits excellent resistance to arc erosion, concerns regarding environmental pollution are driving the industry to gradually transition toward newer, more eco-friendly oxide systems.

As environmental regulations become increasingly stringent, the elimination of cadmium has emerged as a major trend in the industry. The once-dominant silver-cadmium oxide (AgCdO) electrical contacts are gradually being supplanted by eco-friendly alternatives such as silver-tin oxide (AgSnO₂) and silver-copper oxide. However, in an effort to reduce production costs and conserve silver resources, many manufacturers remain committed to optimizing bimetallic structures. For instance, AgCdO bimetal silver rivet contacts produced using advanced cold-heading technology achieve a dual balance of performance and cost-effectiveness by firmly bonding a high-performance working layer to a low-cost copper substrate.

Among the numerous bimetallic combinations, the pairing of silver and copper is highly favored due to their excellent complementary properties. Copper offers superior electrical conductivity and formability, providing the contactor with a stable current path and structural support, while the silver alloy layer is responsible for delivering exceptional resistance to arc erosion. Typical silver-copper composite rivet contacts are commonly found in riveted or laminated configurations; metallurgical bonding-often achieved through processes such as diffusion welding-ensures contact stability under high-current conditions. Furthermore, these types of silver-cadmium oxide bimetal contact rivets continue to play an indispensable role in specific transitional applications.

Beyond the fundamental requirement for electrical conductivity, the structural design of electrical contacts must also address the need for wear resistance and corrosion resistance. In practical applications-whether in humid environments or industrial settings exposed to corrosive gases-high-quality bimetal contact rivets consistently maintain extremely low contact resistance and ensure stable signal transmission. Concurrently, for applications involving moving contacts subject to frequent friction, engineers often opt for AgNi bi-metal electrical silver contacts-specifically those alloyed with nickel-to enhance the material's wear resistance and mechanical strength.

In the specific manufacturing process, precision riveting techniques are of paramount importance. A mature bi-metal Ag/Cu silver contact riveting process not only ensures product consistency but also meets the demands of large-scale automated assembly. Furthermore, in vacuum switches requiring exceptionally high arc-breaking capabilities, the design of the bi-metal silver contacts often necessitates the incorporation of magnetic field control technologies to drive the arc into high-speed rotation, thereby minimizing contact erosion.