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Ag/MeO electrical contact material

Silver metal oxide (Ag/MeO) electrical contact materials are widely used in low-voltage appliances because of their excellent switching operation characteristics.

Among them, silver cadmium oxide (Ag/CdO) electrical contacts are known as “universal contacts” because of their good resistance to arc erosion, anti-fusion welding, low and stable contact resistance and good processing performance.

Due to the pollution of cadmium and its compounds in the whole process of production, use and recycling of Ag/CdO materials (i.e., “cadmium toxicity” pollution), their products and applications have been subject to increasingly strict restrictions, and their production and sale have even been explicitly banned in industrially developed countries such as Europe, the United States and Japan [71], therefore, the research and development of environmentally friendly cadmium-free electrical contact materials have become the focus of attention for electrical contact material workers.

Currently, silver tin oxide (Ag/SnO2) is recognized as the most promising alternative to Ag/CdO as an environmentally friendly electrical contact material.
Ag/SnO, electrical contact materials with high strength, high conductivity and excellent thermal conductivity, easy to prepare and oxide particles dispersion uniform, gradually become the current domestic and foreign electrical materials research hotspots.

In order to understand the resistance of Ag/MeO electrical contact materials to arc erosion and the mechanism of arc erosion, domestic and foreign scholars have studied the arc erosion behavior of Ag/MeO electrical contact materials.Pearce investigated the effect of transport current matrix on the electrical properties of Ag/SnO electrical contacts, and the results showed that the increase of contact bounce force , the choice of bonding method and the use of brass alloys can affect the electrical life of Ag/SnO, electrical contacts under AC4 conditions.

Swingler compared the arc characteristics and arc erosion behavior of Ag/CdO and Ag/SnO electrical contact materials under DC disconnection conditions, and the results showed that the type of metal oxidation had an important effect on the arc characteristics and arc erosion of electrical contact materials during disconnection operation; disconnection at specific currents, Ag/CdO and Ag SnO₂ electrical contact materials showed different arc Ren designed a device to automatically test the resistivity of real-size rivets and tested the voltage and current characteristics of Ag/CdO rivets under different contact forces; meanwhile, the relationship between Ag/CdO electrical contact load and contact resistance was investigated under different currents and loaded and unloaded conditions; furthermore, the relationship between Ag/CdO electrical contact load and The relationship between the contact resistance and the load of Ag/CdO electrical contacts under different currents and loaded and unloaded conditions was investigated; the effects of surface roughness and cleanliness of Ag/CdO rivets on the contact resistance of electrical contacts were further analyzed. The results show that the factors influencing the contact resistance include not only the physical properties of the electrical contact material, contact type (round-flat, flat-flat), contact surface condition (clean, contaminated), but also the contact current and mechanical load during the test. wan investigated the organization and composition of the conditioned and quasi-steady states of the Ag/MeO electrical contacts under the action of the disconnecting arc.

The results showed that pores (pits and porosity on the contact surface) may be produced by the arc; the melt pool liquid viscosity severely affected the shape of the pores; the lower the viscosity the more pits were formed and the higher the viscosity the more porosity was formed; the electrical contact material went through two stages (conditioned and quasi-steady states) with increasing number of operations. In the initial stage, the mass loss of electric contact material is serious, then the mass loss decreases, and after a certain number of operations, the mass loss of electric contact material remains almost stable. The two stages, regulated and quasi-steady state, are both caused by arc erosion due to phase changes in the organization and composition of the electrical contact surface layer.

The arc erosion model depends mainly on the original ratio of Ag and second group elements and on the surface dynamics.Jemaa investigated the effect of load and disconnection speed on the arc duration of pure silver, silver alloy and silver metal oxide electrical contacts. The results showed that inductive loading increases the arc duration of electrical contact materials; under resistive and lamp loads, metal oxide electrical contact materials have a longer arc duration than silver alloy and pure silver; furthermore, under inductive loading, the arc duration decreases square root with increasing breaking speed; however, under resistive loading and high currents, the arc duration decreases linearly with increasing breaking speed.

Devender  studied the arc erosion behavior of Ag/CdO and Ag/SnO, electrical contacts on commercial contactors; they occurred under AC4 conditions and if Ag/SnO was used instead of the contactor, the contactor used for Ag/CdO would have higher arc erosion and vice versa.Wintz [81] found that Ag/SnO electrical contacts at low currents had high and unstable contact resistance. He improved an 18.5 kW contactor by reducing the contact resistance of Ag/SnO by changing the welding method.Yang  conducted a simulation and experimental study of the thermal effects of composite electrical contacts in the electrical life test of a DC relay.

The results showed that the thickness of the Ag/Me0 layer has an important effect on the temperature and stress distribution in the bonding region of the dynamic contact; at the same current, the composite electrical contact is more prone to curling and cracking as the thickness of the Ag/MeO layer increases.Slade [83] investigated the effect of heavy metal release from Ag/CdO and Ag/SnO electrical contacts at high temperatures (800 to 1240°C).

The results showed that Cd is released from Ag/CdO electrical contacts, but only 8% Cd is released even at 1240°C; under the same conditions, Ag/SnO, electrical contacts do not release Sn, but a small amount of Ag is present on the heated electrical contacts.Francisco  studied the contact properties of different Ag/SnO, electrical contact materials under motorcycle loading. The results showed that the resistance to arc erosion of Ag/SnO₂ electrical contact materials containing CuzO was better than that of Ag/CdO and other Ag/SnO₂ electrical contact materials, mainly due to the different chemical properties of the materials.Jeannot [85] studied the effect of commonly used additives on the electrical properties of Ag/Sn₂ electrical contact materials.

The results showed that additives that did not improve the wettability of Ag and SnO₂ and did not react with SnO₂ or Ag did not improve the electrical properties of Ag/SnO, electrical contacts; additives that reduced the wetting angle between Ag and SnO₂ making molten Ag and SnO more wettable improved the electrical properties of Ag/SnO electrical contacts; additives that increased the wetting angle between Ag and SnO, making molten Ag and SnO₂ more The non-wetting additives deteriorated the electrical properties of Ag/SnO₂ electrical contacts. Sun  investigated the modeling of the interaction between Ag/MeO electrical contact materials and the arc to analyze the thermomechanical properties of electrical contact materials, structural properties, and the effect of arc driving force on the arc during arc erosionA model of erosion is given to express the heat-force function during the arc-electrode interaction.Weise  used a simple thermodynamic model to analyze the arc erosion of Ag/CdO and Ag/Sn₂ electrical contact materials. The results showed that when the arc energy was lower than 20 kJ/mol, the modeled silver did not reach the melting point The arc erosion of Ag/MeO contact materials was not very dependent on the oxide type; when the arc energy was greater than 40 kJ/mol, the increased arc energy promoted the oxide sublimation process and reduced the temperature rise.

The effect of arc erosion on electrical contact materials is mainly manifested in the transfer of mass and changes in surface structure, which will in turn react to arc erosion. How to apply suitable characterization techniques to track and observe the mass transfer and surface structure changes of electrical contact materials in real time has become the key to explore the process and mechanism of arc erosion of electrical contact materials. Conventional mass change measurement of electric contact material in some cases ((1) the number of operations is very low and the mass change is very small; (2) the material is transferred from cathode to anode, but due to the extended arc duration material is transferred from anode to cathode again] it is difficult to give a realistic amount of material transfer of electric contact material on a single rivet; in addition, conventional two-dimensional morphological inspection methods (scanning electron microscopy) are difficult to realistically characterize the electric contact material Erosion surface profile and volume erosion changes. The three-dimensional morphology detector can not only give the three-dimensional surface macroscopic morphology of electric contact materials, but also measure the surface profile, shape and position deviation of electric contact materials after arc erosion, with high lateral and longitudinal resolution, and a large measurement depth and measurement range, which provides a possibility for the study of electric contact materials arc erosion surface structure (three-dimensional morphology, surface profile and volume erosion).

inspection methods include mechanical stylus method, scanning laser microscope (SLM), scanning tunneling microscope (STM), atomic force microscope (AFM), and three-dimensional optical profilometer (3DOP).Hasegawa pointed out that STM and AFM, although they have high spatial resolution, are not suitable for evaluating the eroded surface of electric contact materials due to their limited travel distance in the z-axis direction [88]. Three-dimensional optical profilometer can reconstruct the three-dimensional profile of the surface of the object under test by obtaining the relative height of each point through the measurement of the zero optical range difference position of each point of the surface. As early as 1996, MeBride pointed out that 3D optical profilometry can be used to observe the arc erosion morphology of electrical contact materials and to measure the arc erosion surface profile and volume erosion .

Swingle used 3D optical profilometry to observe the arc erosion morphology of Ag/SnO₂ electrical contact materials and to measure the volume change of cathode and anode electrical contacts [90]. Therefore, 3D optical profilers can provide the technology to track and observe the structural changes of arc erosion surface in real time. The most direct effect of arc erosion on the material is the change of material surface structure, which in turn reacts to arc erosion and electrical contact physical phenomena. It can be seen that the in-depth study of the physical phenomena of electrical contact and erosion surface structure is a prerequisite for finding the main factors determining the process of arc erosion and exploring the mechanism of arc erosion. Therefore, how to use suitable research tools to track and characterize the changes of electrical contact physical phenomena and erosion surface structure during arc erosion in real time is the key to the success of the study.

Author

Hello, my name is Eva Xia, and I am currently the Marketing Manager at Yueqing Weup Technology Co., Ltd, located in Wenzhou, Zhejiang, China. With over a decade of experience in the accounting field, I have developed extensive knowledge and skills that enable me to excel in my role. Additionally, I have spent two years working as an English teacher, which enhanced my communication abilities and instilled discipline within me.

Having gained more than three years of valuable experience in overseas sales, I have had the opportunity to expand my horizons and develop a deeper understanding of the commercial landscape. This exposure has nurtured my business understanding and allowed me to navigate diverse markets confidently.

However, despite my accomplishments thus far, I remain dedicated to continuous growth and learning. My current area of focus revolves around electronic switches. It is a fascinating and dynamic field that constantly evolves with technological advancements. By delving deeper into this realm, I aim to enhance my professional knowledge and stay ahead of industry trends.

In summary, as a Marketing Manager at Yueqing Weup Technology Co., Ltd., I bring forth a wealth of experience in accounting coupled with the valuable skills honed during my time as an English teacher. Furthermore, my extensive overseas sales expertise has sharpened my business acumen. With a relentless thirst for knowledge and a specific interest in electronic switches, I strive to enhance my professional capabilities further while contributing positively to our organization’s success.

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Eva Xia,
Marketing Manager at Yueqing Weup Technology Co., Ltd

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