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→Silver-Metal Oxide Materials Ag/CdO, Ag/SnO2, Ag/ZnO
Over the past years, many Ag/CdO contact materials have been replaced by Ag/SnO<sub>2</sub> based materials with 2-14 wt% SnO<sub>2</sub> because of the toxicity of Cadmium. This changeover was further favored by the fact that Ag/SnO<sub>2</sub> contacts quite often show improved contact and switching properties such as lower arc erosion, higher weld resistance, and a significant lower tendency towards material transfer in DC switching circuits <xr id="tab:tab2.30"/> (Table 2.30). Ag/SnO<sub>2</sub> materials have been optimized for a broad range of applications by other metal oxide additives and modification in the manufacturing processes that result in different metallurgical, physical and electrical properties<xr id="tab:tab2.28"/> (Tab. 2.28) und <xr id="tab:tab2.29"/> (Table 2.29).
Manufacturing of Ag/SnO<sub>2</sub> by ''internal oxidation'' is possible in principle, but during heat treatment of alloys containing > 5 wt% of tin in oxygen, dense oxide layers formed on the surface of the material prohibit the further diffusion of oxygen into the bulk of the material. By adding Indium or Bismuth to the alloy the internal oxidation is possible and results in materials that typically are rather hard and brittle and may show somewhat elevated contact resistance and is limited to applications in relays. To make a ductile material with fine oxide dispersion (SISTADOX TOS F) <xr id="fig:fig2.114Micro structure of Ag SnO2 88 12 TOS F"/> (Fig. 2.114) it is necessary to use special process variations in oxidation and extrusion which lead to materials with improved properties in relays. Adding a brazable fine silver layer to such materials results in a semifinished material suitable for the manufacture as smaller weld profiles (SISTADOX WTOS F) <xr id="fig:fig2.116Micro structure of Ag SnO2 92 8 WTOS F"/> (Fig. 2.116). Because of their resistance to material transfer and low arc erosion these materials find for example a broader application in automotive relays <xr id="tab:tab2.31"/> (Table 2.31).
<xr id="fig:Softening of Ag SnO2 88 12P after annealing"/> Fig. 2.100: Softening of Ag/SnO<sub>2</sub> 88/12P after annealing for 1 hr after 40% cold working
<xr id="fig:fig2.101Strain hardening of Ag SnO2 88 12 WPC"/> Fig. 2.101: Strain hardening of Ag/SnO<sub>2</sub> 88/12 WPC by cold working
<xr id="fig:fig2.102Softening of Ag SnO2 88 12 WPC after annealing"/> Fig. 2.102: Softening of Ag/SnO<sub>2</sub> 88/12 WPC after annealing for 1 hr after different degrees of cold working
<xr id="fig:fig2.103Strain hardening of Ag SnO2 86 14 WPC"/> Fig. 2.103: Strain hardening of Ag/SnO<sub>2</sub> 86/14 WPC by cold working
<xr id="fig:fig2.104Softening of Ag SnO2 86 14 WPC"/> Fig. 2.104: Softening of Ag/SnO<sub>2</sub> 86/14 WPC after annealing for 1 hr after different degrees of cold working
<xr id="fig:fig2.105Strain hardening of Ag SnO2 88 12 WPD"/> Fig. 2.105: Strain hardening of Ag/SnO<sub>2</sub> 88/12 WPD by cold working
<xr id="fig:fig2.106Softening of Ag SnO2 88 12 WPD after annealing"/> Fig. 2.106: Softening of Ag/SnO<sub>2</sub> 88/12 WPD after annealing for 1 hr after different degrees of cold working
<xr id="fig:fig2.108Softening of Ag SnO2 88 12 WPX"/> Fig. 2.108: Softening of Ag/SnO<sub>2</sub> 88/12 WPX after annealing for 1 hr after different degrees of cold working
<xr id="fig:fig2.107Strain hardening of Ag SnO2 88 12 WPX"/> Fig. 2.107: Strain hardening of Ag/SnO<sub>2</sub> 88/12 WPX by cold working
<xr id="fig:fig2.109Micro structure of Ag SnO2 92 8 PE"/> Fig. 2.109: Micro structure of Ag/SnO<sub>2</sub> 92/8 PE: a) perpendicular to extrusion direction
b) parallel to extrusion direction
<xr id="fig:fig2.110Micro structure of Ag SnO2 88 12 PE"/> Fig. 2.110: Micro structure of Ag/SnO<sub>2</sub> 88/12 PE: a) perpendicular to extrusion direction
b) parallel to extrusion direction
<xr id="fig:fig2.111Micro structure of Ag SnO2 88 12 PW"/> Fig. 2.111: Micro structure of Ag/SnO<sub>2</sub> 88/12 PW: a) perpendicular to extrusion direction
b) parallel to extrusion direction
<xr id="fig:fig2.112Micro structure of Ag SnO2 98 2 PX"/> Fig. 2.112: Micro structure of Ag/SnO<sub>2</sub> 98/2 PX: a) perpendicular to extrusion direction
b) parallel to extrusion direction
<xr id="fig:fig2.113Micro structure of Ag SnO2 92 8PX"/> Fig. 2.113: Micro structure of Ag/SnO<sub>2</sub> 92/8 PX: a) perpendicular to extrusion direction
b) parallel to extrusion direction
<xr id="fig:fig2.114Micro structure of Ag SnO2 88 12 TOS F"/> Fig. 2.114: Micro structure of Ag/SnO<sub>2</sub> 88/12 TOS F: a) perpendicular to extrusion direction
b) parallel to extrusion direction
<xr id="fig:fig2.115Micro structure of Ag SnO2 86 14 WPC"/> Fig. 2.115: Micro structure of Ag/SnO<sub>2</sub> 86/14 WPC: a) perpendicular to extrusion direction
b) parallel to extrusion direction, 1) AgSnO<sub>2</sub> contact layer, 2) Ag backing layer
<xr id="fig:fig2.116Micro structure of Ag SnO2 92 8 WTOS F"/> Fig. 2.116: Micro structure of Ag/SnO<sub>2</sub> 92/8 WTOS F: a) perpendicular to extrusion direction
b) parallel to extrusion direction,1) AgSnO<sub>2</sub> contact layer, 2) Ag backing layer
<xr id="fig:fig2.117Micro structure of Ag SnO2 88 12 WPD"/> Fig. 2.117: Micro structure of Ag/SnO<sub>2</sub> 88/12 WPD: parallel to extrusion direction
1) AgSnO<sub>2</sub> contact layer, 2) Ag backing layer
<xr id="fig:fig2.118Micro structure of Ag SnO2 88 12 WPX"/> Fig. 2.118: Micro structure of Ag/SnO<sub>2</sub> 88/12 WPX:parallel to extrusion direction
1) AgSnO<sub>2</sub> contact layer, 2) Ag backing layer
<xr id="fig:fig2.119Micro structure of Ag SnO2 86 14 WPX"/> Fig. 2.119: Micro structure of Ag/SnO<sub>2</sub> 86/14 WPX: a) perpendicular to extrusion direction
b) parallel to extrusion direction, 1) AgSnO<sub>2</sub> contact layer, 2) Ag backing layer
</div>
</figure>
<figure id="fig:fig2.101Strain hardening of Ag SnO2 88 12 WPC">
[[File:Strain hardening of Ag SnO2 88 12 WPC.jpg|left|thumb|<caption>Strain hardening of Ag/SnO<sub>2</sub> 88/12 WPC by cold working</caption>]]
</figure>
<figure id="fig:fig2.102Softening of Ag SnO2 88 12 WPC after annealing">
[[File:Softening of Ag SnO2 88 12 WPC after annealing.jpg|left|thumb|<caption>Softening of Ag/SnO<sub>2</sub> 88/12 WPC after annealing for 1 hr after different degrees of cold working</caption>]]
</figure>
<figure id="fig:fig2.103Strain hardening of Ag SnO2 86 14 WPC">
[[File:Strain hardening of Ag SnO2 86 14 WPC.jpg|left|thumb|<caption>Strain hardening of Ag/SnO<sub>2</sub> 86/14 WPC by cold working</caption>]]
</figure>
<figure id="fig:fig2.104Softening of Ag SnO2 86 14 WPC">
[[File:Softening of Ag SnO2 86 14 WPC.jpg|left|thumb|<caption>Softening of Ag/SnO<sub>2</sub> 86/14 WPC after annealing for 1 hr after different degrees of cold working</caption>]]
</figure>
<figure id="fig:fig2.105Strain hardening of Ag SnO2 88 12 WPD">
[[File:Strain hardening of Ag SnO2 88 12 WPD.jpg|left|thumb|<caption>Strain hardening of Ag/SnO<sub>2</sub> 88/12 WPD by cold working</caption>]]
</figure>
<figure id="fig:fig2.106Softening of Ag SnO2 88 12 WPD after annealing">
[[File:Softening of Ag SnO2 88 12 WPD after annealing.jpg|left|thumb|<caption>Softening of Ag/SnO<sub>2</sub> 88/12 WPD after annealing for 1 hr after different degrees of cold working</caption>]]
</figure>
<figure id="fig:fig2.108Softening of Ag SnO2 88 12 WPX">
[[File:Softening of Ag SnO2 88 12 WPX.jpg|left|thumb|<caption>Softening of Ag/SnO<sub>2</sub> 88/12 WPX after annealing for 1 hr after different degrees of cold working</caption>]]
</figure>
<figure id="fig:fig2.107Strain hardening of Ag SnO2 88 12 WPX">
[[File:Strain hardening of Ag SnO2 88 12 WPX.jpg|left|thumb|<caption>Strain hardening of Ag/SnO<sub>2</sub> 88/12 WPX by cold working</caption>]]
</figure>
<figure id="fig:fig2.109Micro structure of Ag SnO2 92 8 PE">
[[File:Micro structure of Ag SnO2 92 8 PE.jpg|left|thumb|<caption>Micro structure of Ag/SnO<sub>2</sub> 92/8 PE: a) perpendicular to extrusion direction b) parallel to extrusion direction</caption>]]
</figure>
<figure id="fig:fig2.110Micro structure of Ag SnO2 88 12 PE">
[[File:Micro structure of Ag SnO2 88 12 PE.jpg|left|thumb|<caption>Micro structure of Ag/SnO<sub>2</sub> 88/12 PE: a) perpendicular to extrusion direction b) parallel to extrusion direction</caption>]]
</figure>
<figure id="fig:fig2.111Micro structure of Ag SnO2 88 12 PW">
[[File:Micro structure of Ag SnO2 88 12 PW.jpg|left|thumb|<caption>Micro structure of Ag/SnO<sub>2</sub> 88/12 PW: a) perpendicular to extrusion direction b) parallel to extrusion direction</caption>]]
</figure>
<figure id="fig:fig2.112Micro structure of Ag SnO2 98 2 PX">
[[File:Micro structure of Ag SnO2 98 2 PX.jpg|left|thumb|<caption>Micro structure of Ag/SnO<sub>2</sub> 98/2 PX: a) perpendicular to extrusion direction b) parallel to extrusion direction</caption>]]
</figure>
<figure id="fig:fig2.113Micro structure of Ag SnO2 92 8PX">
[[File:Micro structure of Ag SnO2 92 8PX.jpg|left|thumb|<caption>Micro structure of Ag/SnO<sub>2</sub> 92/8 PX: a) perpendicular to extrusion direction b) parallel to extrusion direction</caption>]]
</figure>
<figure id="fig:fig2.114Micro structure of Ag SnO2 88 12 TOS F">
[[File:Micro structure of Ag SnO2 88 12 TOS F.jpg|left|thumb|<caption>Micro structure of Ag/SnO<sub>2</sub> 88/12 TOS F: a) perpendicular to extrusion direction b) parallel to extrusion direction</caption>]]
</figure>
<figure id="fig:fig2.115Micro structure of Ag SnO2 86 14 WPC">
[[File:Micro structure of Ag SnO2 86 14 WPC.jpg|left|thumb|<caption>Micro structure of Ag/SnO<sub>2</sub> 86/14 WPC: a) perpendicular to extrusion direction b) parallel to extrusion direction, 1) AgSnO2 contact layer, 2) Ag backing layer</caption>]]
</figure>
<figure id="fig:fig2.116Micro structure of Ag SnO2 92 8 WTOS F">
[[File:Micro structure of Ag SnO2 92 8 WTOS F.jpg|left|thumb|<caption>Micro structure of Ag/SnO<sub>2</sub> 92/8 WTOS F: a) perpendicular to extrusion direction b) parallel to extrusion direction,1) AgSnO2 contact layer, 2) Ag backing layer</caption>]]
</figure>
<figure id="fig:fig2.117Micro structure of Ag SnO2 88 12 WPD">
[[File:Micro structure of Ag SnO2 88 12 WPD.jpg|left|thumb|<caption>Micro structure of Ag/SnO<sub>2</sub> 88/12 WPD: parallel to extrusion direction 1) AgSnO2 contact layer, 2) Ag backing layer</caption>]]
</figure>
<figure id="fig:fig2.118Micro structure of Ag SnO2 88 12 WPX">
[[File:Micro structure of Ag SnO2 88 12 WPX.jpg|left|thumb|<caption>Micro structure of Ag/SnO<sub>2</sub> 88/12 WPX:parallel to extrusion direction 1) AgSnO2 contact layer, 2) Ag backing layer</caption>]]
</figure>
<figure id="fig:fig2.119Micro structure of Ag SnO2 86 14 WPX">
[[File:Micro structure of Ag SnO2 86 14 WPX.jpg|left|thumb|<caption>Micro structure of Ag/SnO<sub>2</sub> 86/14 WPX: a) perpendicular to extrusion direction b) parallel to extrusion direction, 1) AgSnO2 contact layer, 2) Ag backing layer</caption>]]
</figure>
