Improving dispersion of SnO2 nanoparticles in Ag–SnO2 electrical contact materials using template method

• Template method was studied as a way to improve SnO2 dispersion in AgSnO2 contact materials.
• Filter paper and starch were used as template materials in composite powder preparation.
• Method of introduction of nanoparticles has major impact on structure dependent properties.
• AgSnO2 produced using starch template shows a hardness enhancement of almost 20%.
• The template method can be successfully used in production of AgSnO2 contacts.

Considering that improvement in the performance of Ag–SnO2 electrical contact materials can be realized by an increase in metal oxide dispersion, the influence of SnO2 nanoparticles and method of their introduction in silver matrix on microstructure and physical properties such as density, porosity, hardness and electrical conductivity were studied. The SnO2 nanoparticles were introduced by conventional powder mixing and by template method using filter paper and soluble starch as templates. All investigated samples were produced by subsequent pressing, sintering of the obtained powder mixtures and composites followed by mechanical treatment. Microstructural analysis revealed that the Ag–SnO2 samples prepared by template method exhibit finer dispersion than their conventionally prepared counterpart. After sintering and forging those samples were found to have higher hardness, density and lower porosity. As a result of greater dispersion hardening, the highest value of hardness was measured for the sample prepared using soluble starch as a template. The measured values of electrical conductivity of all investigated samples are comparable with conductivities of Ag–SnO2 electrical contact materials of this type.

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