THE PROJECT IN FIGURES
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NUMBER OF FORMULATIONS DESIGNED
Nearly 200 formulations were designed and tested. Out of all the compositions, only two were finally selected thanks to the correct achievement of desired properties in terms of tarnishing resistance, mechanical properties and cost
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MAN HOURS WORKED IN THE LAB
2000 hours totally dedicated to this project from June 2014 till February 2016.
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AMOUNT OF SILVER PROCESSED FOR THE LAB TESTS
In our laboratory, more than 100 kg of fine silver were used for tests related to SILNOVA® project, before any industrial test started. After that, casting sessions were performed, for a total number of 100 flasks castings, and more than 50 kg of alloy were produced in sheet and bar form.
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LAB ACTIVITY FOR METALLOGRAPHIC INVESTIGATION AND CHARACTERIZATION
Total 400 samples for evaluation of internal porosity and surface quality through cross section analysis; 1600 images captured during this investigation. More than 250 hardness measurements in the as cast state. Total 50 age hardening profiles done summing up to other 200 hardness measurements. Total 50 determinations of crystal grains in the as cast state.
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NUMBER OF ACCELERATED TESTS PERFORMED
40 sessions of accelerated tarnishing test were performed; in 30 sessions the two “screening test” (TAA + Perspiration test) were performed on lab samples; in the remaining 10 sessions all the six selected reference tests were performed, including finished jewellery pieces like rings, plates, chains.
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EXTERNAL PARTIES INVOLVED IN THE PROJECT
3 jewelry manufacturing companies (for production of samples and industrial scale tests).
3 Legor Group branches (employees using bracelets for real-life tests).
PROJECT TIME FRAME
from June 2014 to June 2015
from June 2014 to June 2015
from June 2015 to Feb 2016
OPERATING PROCEDURES
To assess SILNOVA® performance, we tested it comparatively with positive and negative references:
BENCHMARK
TO REACH
NI-PD-FREE 375‰ WHITE GOLD
The 375‰ white gold alloy with Ni-Pd-free, Ag-based formulation is used as our positive benchmark, with its resistance currently being remarkably higher than that of any silver 925‰ alloy and the best among 375‰ gold alloys. Our set goal is that the new silver alloy should have a tarnishing resistance comparable or higher than that of the 375‰ gold alloy.
POSITIVE
REFERENCE
GERMANIUM-BASED SILVER 960‰
The Ge-based silver alloy is presently one of the best choices in terms of tarnishing resistance available on the market; it can be considered the positive reference on silver alloys.
NEGATIVE
REFERENCE
STERLING SILVER 925‰
Sterling silver is used as negative reference in terms of corrosion resistance.
