| Sterling silver has so beautiful luster and low prices, that it is widely used in jewelry and loved by consumers. But the silver is very easily sulfide to black in the air, which affect the appearance. And silver is too soft to firmly inlaid stones, that restrict the promotion of silver charms.Currently, it is often plated rhodium on 925 silver’s surface to protect the tarnishing of silver.However, when the film is worn out, internal silver alloy will continue to tarnishing. This is the main problem of jewelry silver and products during consumption.So the most effective method to protect the tarnishing of silver alloy, enhance hardness is alloy ing.Indium has bright color, and compared with silver has blue cast.Indium is very stable in the air, is not easily to lose luster of oxidation.The development and application of rare metal Indium’s market is insufficient, that a lot of indium is hoarding. Some scholars proposed the ideal that collect indium in crowds, through the application as jewelry is the effective measure. Prepared the silver-indium alloy, base metal (Sn,Zn) silver-indium alloy and rare earth (Y) silver-indium alloy.Comparative ana-lysis the result of mechanical properties and corrode tarnishing experiment,which is more super-ior.Finally,prepared for a piece of silver-indium alloy jewelry.Analysis of detection means include OM, microhardness, fiber spectrometer, XRD, SEM coupled with EDS, DTA, XPS. Analysis the result of sulfied corrosion, artificial sweat corrosion, oxidation, hardness and reflectance test.The following results were obtained:(1) The result of reflectivity test found that the silver indium alloy has high reflectance. Sliver-indium alloy with Y addition has yellow hues, compared to the pure silver has slightly warm color. Sliver-indium alloy with Sn, Zn addition is whiter than sliver-indium alloy with Y addition. Indicate that silver-indium alloy has the potential value used as jewelry.(2) The silver-indium alloy with indium addition less than 5% has larger grain. With the addition of indium, alloy gradually precipitate mixed branch crystal. The addition of rare earth and Sn, Zn has obvious fine dendrite, and obviously improves the hardness of the cast alloy. Y exists on grain boundaries, and pin grain boundaries that inhibit the motion of dislocation. With the addition of indium,three alloys all has the second phase precipitation, that has the effect of second phase strengthening to improve the hardness of the cast alloy.(3) Silver-indium alloy with Y addition has stronger anti corrosion than the 925 silver and silver-indium alloy with Sn, Zn addition. Silver-indium alloy with Y additi-on has excellent anti tarnishing capability,and has lowest rate of weight gain.The sulfied corrosion is slow intergra-nular corrosion.However,the silver-indium alloy with Sn, Zn addition sulfied corrosion become seriously,when the oxide film is corroded. Copper of 925 silver is mainly sulfided, generated a large of black product on the surface of the alloy.(4) The result of pour experiment of Silver-indium alloy and pure silver, found that the cross-section of silver-indium casts has shrinkage cavity. But the surface is smooth without other casting defects.The formation of shrinkage cavity may be due to fast cooling speed that made silver-indium alloy has the dendrite, affect the fluidity of the alloy.The cross-section of pure silver casts has a large number of small holes form shrinkage, and inclusions. Cause surface looks rough that the lustre is weaker than the silver-indium alloy. |
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