The 
effects of additional elements on the measured 
color difference (DE*) Ag-Cu-Zn-alloy is shown in 
Figure 3. A lower DE value indicates better tarnish 
resistance. However, the DE values in Figure 3 
suggest that the samples with 0.1%Si provide 
optimum tarnish resistance than that of 0.3%Si in 
all testing time. The tarnishing is non-uniform and, 
regarding severity, can be distinguished as three 
types : 1) general tarnish which is light brown in 
color, 2) local attack which is dark brown in color, 
and 3) severe local attack which is very dark in 
color. It appears that, although overall tarnish 
resistance is improved, the alloy additions can 
result in localized attack that is related with the 
phase distribution in the microstructure. In general 
it would concluded that an increase in alloying 
elements (i.e. decrease in copper content or 
decrease in eutectic structure) increases tarnish 
resistance as also mentioned in a previous study. 
However, it is also mentioned
(4)
 that tarnishing is 
possibly form by more than one chemical reaction, 
several other tests and tarnish mechanisms exist 
can lead to different results. It was reported that 
silicon-oxide layer formation on the surface can be 
formed on the silicon added silver sterling. 
Microstructure-related mechanism from this layer 
can be contributed to tarnish resistance.
 
The effects of additional elements on the measured color difference (DE*) Ag-Cu-Zn-alloy is shown in Figure 3. A lower DE value indicates better tarnish resistance. However, the DE values in Figure 3 suggest that the samples with 0.1%Si provide optimum tarnish resistance than that of 0.3%Si in all testing time. The tarnishing is non-uniform and, regarding severity, can be distinguished as three types : 1) general tarnish which is light brown in color, 2) local attack which is dark brown in color, and 3) severe local attack which is very dark in color. It appears that, although overall tarnish resistance is improved, the alloy additions can result in localized attack that is related with the phase distribution in the microstructure. In general it would concluded that an increase in alloying elements (i.e. decrease in copper content or decrease in eutectic structure) increases tarnish resistance as also mentioned in a previous study. However, it is also mentioned(4) that tarnishing is possibly form by more than one chemical reaction, several other tests and tarnish mechanisms exist can lead to different results. It was reported that silicon-oxide layer formation on the surface can be formed on the silicon added silver sterling. Microstructure-related mechanism from this layer can be contributed to tarnish resistance.
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