Ag/SnO2 has gained prominence in electrical contact materials due to its excellent resistance to arc erosion and fusion welding. This study clarifies how two oxidation methods (billet oxidation and powder pre-oxidation) under different oxidants (air and air + Ag2O) influence the microstructure and properties of Ag/SnO2Bi2O2-CuO materials. The results indicate that the materials oxidized in air using both methods exhibit a network-like microstructure, whereas those oxidized in air + Ag2O show an island-like microstructure. Notably, the most homogeneous microstructure is achieved through powder pre-oxidation in air + Ag2O, yielding the smallest average Ag grain size (2.69 mu m) and optimal physical properties. The corresponding materials exhibit superior physical properties, with a relative density of 98 %, a hardness of 70 HV, and an electrical conductivity of 41 MS/ m.

The influence of oxygen partial pressure on the microstructure, element distribution, and physical properties of Ag-Sn-In-Ni-Sb alloy after oxidation was investigated by thermodynamic calculation, XRD, OM, EPMA, and AFM. The results show that the higher the oxygen partial pressure is, the more fully the alloy is oxidized, the smaller the oxide particle size is, the more uniform the microstructure is, and the better the physical properties of the oxidized samples are. The relative density of the sample oxidized at 0.9 MPa is 98.3%, the conductivity is 60.2% (IACS), and the hardness is HV 130.1. The NiSbSn intermetallic compound in Ag-Sn-In-Ni-Sb alloy is oxidized to six different oxide configurations. In addition, the relationships among oxygen partial pressure, oxide particle size and physical properties were established, and the influencing mechanism of oxygen partial pressure on microstructure was also discussed.

The effects of Sb and Cr on the internal oxidation behavior of Ag-6.5Sn-2.5In-0.5Ni-based alloys were investigated using quasi-in-situ oxidation, electron probe microanalysis (EPMA), and X-ray diffraction (XRD). The results showed that Sb and Cr altered the oxidation pathway and phase evolution in distinctly different ways. In Ag-6.5Sn-2.5In-0.5Ni-0.5Sb, the NiSbSn phase was fully oxidized, producing four characteristic oxide morphologies. In Ag-6.5Sn-2.5In-0.5Ni-0.5Cr, the NiSn, Cr(Ni), and NiCrSn phases were completely oxidized, resulting in six oxide types. Quasi-in-situ observations revealed the sequential oxidation of individual phases and the associated microstructural evolution. The difference in oxidation behavior indicates that Sb and Cr play different roles in phase stability, oxidation progression, and oxide distribution, leading to distinct internal oxidation mechanisms. These results provide insight into alloying-element effects on internal oxidation and guidance for the design of Ag-SnO2 electrical contact materials.

The oxidation mechanism of multi-element silver-based alloys remains unclear. The alloy powders of Ag-Sn-In-La-Ni, Ag-Sn-In-La-Te and Ag-Sn-In-La-Ni-Te were oxidized in air at 850℃, and thermodynamic calculations and microstructure analyses were carried out. The results show that selective oxidation has occurred in all alloys, forming core–shell structures. In addition, the oxidation kinetics all follow the rule of being linear first and then parabolic. The in-situ oxidation of Ni element promotes the densification of oxides, thereby slowing down the oxidation process. The defects caused by the sublimation of TeO2 accelerate oxidation. While the synergistic effect of Ni and Te leads to more widely distributed structural discontinuities in the oxide layer, thereby accelerating oxide growth.

The internal oxidation of multicomponent Ag-based alloys is controlled not only by oxygen diffusion through the Ag matrix but also by the constitution and reactivity of solute-rich secondary phases. However, the phase-specific roles of minor Sb and Cr additions remain insufficiently clarified. In this work, Ag-6.5Sn-2.5In-0.5Ni-0.5Sb and Ag-6.5Sn-2.5In-0.5Ni-0.5Cr alloys were investigated by high-pressure oxidation, quasi-in-situ oxidation, X-ray diffraction, and electron probe microanalysis. After oxidation at 750 °C in pure O2 under pO2 ≈ 0.9 MPa, full-thickness cross-sectional observations revealed inward oxidation from both surfaces toward the specimen center, leaving a residual Ag-rich unoxidized core. The Cr-containing alloy showed a larger inward oxidation depth than the Sb-containing alloy, suggesting a higher degree of internal oxidation. Quasi-in-situ observations further indicated distinct phase-controlled oxidation features. In the Sb-containing alloy, In and Sn dissolved in the Ag matrix appeared to oxidize preferentially, followed by delayed oxidation of Ni-Sb-Sn-rich secondary phases and accompanied by oxygen ingress and outward redistribution of Sn, Sb, and Ni. In the Cr-containing alloy, Cr-rich regions showed preferential early-stage oxidation, whereas Ni-Sn-rich and mixed Ni-Cr-Sn regions were associated with complex Ni-, Sn-, Cr-, and O-containing oxide configurations at later stages. These results suggest that Sb favors a relatively sequential oxidation pathway, while Cr promotes reactive Cr-bearing regions and multiphase-coupled oxidation. This phase-dependent mechanism provides guidance for tailoring oxide morphology and optimizing high-pressure internal oxidation processing in Ag-SnO2-based electrical contact materials. The findings also highlight the importance of controlling secondary-phase type, distribution, and reactivity during alloy design.

Ag/TisAlC composites have emerged as environmentally friendly alternatives to traditional Ag/CdO electrical contact materials, owing to the excellent wettability and electrical conductivity of TisAlC2. However, its limited thermal stability and moderate oxidation sensitivity hinder wider applications. To address these challenges, the thermal stability and oxidation behavior of Ag/TisAlC heated powders and compacts under different sintering conditions were systematically investigated using X-ray diffraction (XRD), thermogravimetric-differential scanning calorimetry (TG-DSC), optical microscopy (OM), scanning electron microscopy (SEM), electron probe microanalysis (EPMA) and electron backscattered diffraction (EBSD). The results demonstrate that controlled oxidation of TisAlC can enhance the physical properties of Ag/TisAlC compacts. In particular, the study highlights the distinct oxidation behaviors of Ti and Al atoms during sintering and the formation of compositionally different oxide shells. These differences were found to strongly correlate with the staged oxidation characteristics of TisAlC2, offering insights into optimizing the thermal stability and performance of Ag/TisAlC2 electrical contact materials.

Ag–SnO2Sb2O3 materials prepared by internal oxidation technology have excellent electrical properties. Here Ag–SnO2Sb2O3 materials are fabricated by four kinds of different oxidation ways. Influence of oxidation way on microstructure and oxides distribution is investigated and the formation mechanism of Ag–SnO2Sb2O3 materials is discussed. The oxidation effect of billet oxidation in air + Ag2O is the best and the oxides distribution is the most uniform and the physical properties (relative density: 97.2

Download This Paper Open PDF in Browser Add Paper to My Library Share: Permalink Using these links will ensure access to this page indefinitely Copy URL Copy DOI

Ag/Ti2AlC electrical contact material is a new type of environmentally friendly alternative material for Ag/CdO due to the good wettability and conductivity of Ti2AlC. However, the thermal stability and moderate oxidation sensitivity of Ti2AlC put restrictions on Ag/Ti2AlC materials manufacturing and application. Therefore, the thermal stability and oxidation behavior of Ti2AlC and Ag/Ti2AlC in air and Ar were analyzed by TG-DSC, XRD, SEM, EPMA and thermodynamic calculation. The practical periodic oxidation behavior of Ti2AlC and mixed Ag/ 10Ti2AlC powders at 300-900 degrees C in air and Ar atmosphere was studied. The negative effect of Ag diffusion into Ti2AlC particles on Ti2AlC' s thermal stability was demonstrated. In addition, the different behavior of Ti and Al atom during the sintering process of Ag/10Ti2AlC in air at different temperature were also discussed and combined with the periodic oxidation of Ti2AlC.

In order to investigate the effect of Sb2O3 on the interface wettability between Ag and SnO2, the wetting behavior between Ag and SnO2 substrate with different Sb2O3 content at different temperatures (1050 degrees C, 1200 degrees C and 1350 degrees C) is studied by high-temperature contact angle wetting apparatus. The results indicate that the interface wettability between Ag and SnO2 can be improved by adding Sb2O3. The wetting process changes from non-reactive wetting to reactive wetting after adding Sb2O3. In addition, the interface wettability between silver and SnO2 substrate decreases with the increasing of Sb2O3 content. In this work, the optimal adding content of Sb2O3 to improve the interface wettability between Ag and SnO2 is 5 wt%.

Ag/SnO2In2O3 materials prepared by internal oxidation have excellent resistance to welding and arc erosion. However, oxides distribution will have a significant influence on its final performance. Here influence mechanism of oxidant (air, air+Ag2O) and sample state (powders, green compacts) on the oxidation behavior of Ag-4.93Sn-3.56In alloy powders is discussed. Oxides accumulate on the surface when Ag-4.93Sn-3.56In alloy powders are oxidized in air while they uniformly distribute in inner when they are oxidized in air+Ag2O. In the sample with Ag2O, oxygen in atomic state can be supplied by the decomposition of Ag2O and easily absorbed into the Ag-alloy matrix to perform the oxidization of alloy elements, but in the case of O2 in air there is a high barrier at the surface of Ag-alloy powders for O2 to become [O] in the atomic state to be absorbed into the Ag-matrix. In air, Ag-4.93Sn-3.56In alloy powders are oxidized more fully than the green compacts, their oxidation behavior is similar but the oxidation mechanism is different. However, in air+Ag2O, Ag-4.93Sn-3.56In alloy powders and green compacts both are oxidized fully, and their oxidation behavior and mechanism are similar.

Download This Paper Open PDF in Browser Add Paper to My Library Share: Permalink Using these links will ensure access to this page indefinitely Copy URL Copy DOI

Arc erosion behavior of Ag/Ni electrical contact materials with different Ni content under 50,000 operation numbers was investigated used by 3DOP, SEM and EPMA. The results indicated that the arc erosion of Ag/Ni electrical contact materials fabricated by sintering-extrusion technology was more and more serious with the Ni content increase from 10 to 20 wt %. There were arc erosion craters on anode and arc erosion convex peaks on cathode, and the arc erosion area decreased with the increase of Ni content. The micro-morphology characteristic of arc erosion was slightly different due to the different Ni content. Layer-like distribution of elements Ni and Ag was found on cathode of Ag/15Ni and Ag/20Ni, which was resulted from the difference of physical properties between Ag and Ni and the limited solubility of Ni in liquid state Ag.

Ag/SnO2 electrical contact material is currently recognized as the most promising environmentally friendly alternative material, but it has the problems of difficult processing and poor wettability between Ag matrix and SnO2 particles. Ag/SnO2Bi2O3CuO composite materials are prepared by reaction synthesis and powder metallurgy technology and the influence of different technology on the microstructure and properties are analyzed and discussed in this paper. The results indicate that the main phases in the Ag/SnO2Bi2O3CuO composite materials prepared by two kinds of technology are Ag, SnO2 and Bi2Sn2O7. The second phase oxide particles in Ag/SnO2Bi2O3CuO composite materials prepared by two kinds of technology mainly have six kinds of distribution position. The physical and mechanical properties of Ag/SnO2Bi2O3CuO composite materials prepared by reaction synthesis technology are better than those by powder metallurgy technology. In addition, the microstructure of Ag/SnO2Bi2O3CuO composite materials prepared by the reaction synthesis technology is more uniform and the distribution of the second phase oxide particles is more dispersive than that by powder metallurgy technology. The difference of microstructure of Ag/SnO2Bi2O3CuO prepared by two kinds of technology mainly occurs in the raw materials and the process of sintering and reaction.

Oxidation of Ag-Sn alloy powders is important technology for Ag-SnO2 electrical contact materials. Here the influence of oxidant on the oxidation behavior of Ag-5.08Sn-3.14Sb alloy powders was discussed. It can be found that the binding energy of all elements after oxidation in air is different from in air + Ag2O. Oxidation in air, the powder surface becomes rough and appears peeling, elements Sn, Sb and O distribute on the surface, oxides form on the powder surface. But oxidation in air + Ag2O, the powder surface is smooth, all elements uniformly distribute on the silver matrix and internal oxidation is occurred.

The oxidation behavior of Ag-9.8Sn-1.3Bi-0.4Cu alloy powders is investigated used by XRD, SEM, EPMA and TEM. The results show that the oxidation behavior in air and air+Ag2O is different for Ag-9.8Sn-1.3Bi-0.4Cu microparticles, but that is similar for Ag-9.8Sn-1.3Bi-0.4Cu nanoparticles. The size of oxides formed in air is larger than that in air+Ag2O and the size of CuO is larger than that of SnO2 and Bi2Sn2O7. The oxides mainly distribute on powder surface in air oxidation, while those mainly distribute on grain boundaries in air+Ag2O oxidation. The nucleation priority order of oxides is SnO2 >Bi2O3 >Bi2Sn2O7 >CuO during oxidation both in air and air+Ag2O.

Ag/CuO materials have been widely used in low-voltage switches due to their high welding resistance and low resistivity, but the effect mechanism of arc erosion on the internal structure and composition was not clear. This paper presented arc erosion behavior of Ag/CuO materials under different operation numbers. The arc erosion morphology was characterized by a three-dimensional profilometer and SEM, and the composition and element distribution were analyzed by electron probe micro-analyzer. Results showed that some new and different arc erosion morphologies were observed on contact surface. The content of Cu and O dissolved in Ag matrix on the arc erosion zone was higher than that on the normal zone. In addition, the content of Cu and O dissolved in Ag matrix on the anodic arc erosion zone was higher than that on the cathodic. The copper oxide particles in the silver molten pool underwent a series of chemical reactions during the arc erosion and formed some new substances.

The eco-friendly Ag/SnO2 composites are the most promising substitution of Ag/CdO contact materials, but the poor wettability between liquid Ag and SnO2 limits its industrial application. This paper presents the first study on influence of La2Sn2O7 on wettability between liquid Ag and SnO2. The wetting angle was measured by substrate drop method, and the microstructure and element diffusion in the wetting interface were analyzed by Electron Probe Micro-Analyzer. Results show that La2Sn2O7 decreases the wetting angle between liquid Ag and SnO2, and the wettability is the best when adding 25 wt% La2Sn2O7 at our all testing temperature. The interface between Ag and SnO2 changes from flat to wavy after adding La2Sn2O7. The diffusion and infiltration in the interface between Ag and La2Sn2O7 is significantly helpful to improve the wettability between Ag and SnO2. (C) 2020 Elsevier B.V. All rights reserved.