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Changes
→Silver-Metal Oxide Materials Ag/CdO, Ag/SnO2, Ag/ZnO
:'''b) Powder blending on the basis of doped powders''' <br> For incorporation of additive oxides in the SnO<sub>2</sub> powder, the reactive spray process has shown advantages. This process starts with a waterbased solution of the tin and other metal compounds. This solution is nebulized under high pressure and temperature in a reactor chamber. Through the rapid evaporation of the water, each small droplet is converted into a salt crystal and from there gets transformed by oxidation into a tin oxide particle in which the additive metals are distributed evenly as oxides. The so created doped AgSnO<sub>2</sub> powder is then mechanically mixed with silver powder.
:'''c) Powder blending based on coated oxide powders''' <br> In this process, tin oxide powder is blended with lower meting melting additive oxides such as for example Ag<sub>2</sub> MoO<sub>4</sub> and then heat treated. The SnO<sub>2</sub> particles are coated in this step with a thin layer of the additive oxide.
:'''d) Powder blending based on internally oxidized alloy powders''' <br> A combination of powder metallurgy and internal oxidation this process starts with atomized Ag alloy powder which is subsequently oxidized in pure oxygen. During this process the Sn and other metal components are transformed to metal oxide and precipitated inside the silver matrix of each powder particle.
:'''e) Powder blending based on chemically precipitated compound powders''' <br> A silver salt solution is added to a suspension of for example SnO<sub>2</sub> together with a precipitation agent. In a chemical reaction, silver and silver oxide respectively are precipitated around the additive metal oxide particles, who act as crystallization sites. Further chemical treatment then reduces the silver oxide with the resulting precipitated powder, being a mix of Ag and SnO<sub>2</sub>.
Further processing of these differently produced powders follows the conventional processes of pressing, sintering and hot extrusion to wires and strips. From these contact parts, contact rivets and tips are manufactured. To obtain a brazable backing, the same processes as used for Ag/CdO are applied. As for Ag/CdO, larger contact tips can also be manufactured using the press-sinter-repress (PSR) process (<xr id="tab:Physical Properties of Powder Metallurgical Silver-Metal Oxide Materials with Fine Silver Backing Produced by the Press-Sinter-Repress Process"/>)<!--(Table 2.27)-->.
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