RU2479655C1 - Alloy based on palladium assay 500 - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: alloy based on palladium assay 500 contains the following components, wt %: palladium - 50.0-50.5; silver - 38-40; silicon - 0.1-0.2; copper is the rest.

EFFECT: achievement of optimum hardness, coincidence as to sample and colour with primary palladium alloy having assay 500, which meets EU directives and allows using the alloy at jewellery manufacture.

1 tbl

Description

The present invention relates to the field of metallurgy of palladium-based alloys intended for the manufacture of jewelry mainly from a sample of palladium 500 alloy.

A known alloy containing 50-85 wt.% Palladium, 5-40 wt.% Cobalt and / or copper, 1-1.5 wt.% Gallium, not more than 5 wt.% Modifier (nickel, gold, indium, ruthenium or tin or a mixture thereof), not more than 1 wt.% boron, not more than 0.5 wt.% rhenium and / or iridium (US 4387072, 06/07/1983, C22C 5/04).

This jewelry alloy has high strength properties (Vickers hardness of more than 150), but contains cobalt, which is toxic, is an allergen and is not recommended for use in products that come into long-term contact with human skin by EEC directives.

The composition closest to the invention is an alloy based on palladium 500 of the PdSrN sample containing 50.0-50.5 wt.% Palladium, 44.5-45.5 wt.% Silver and nickel - the rest (State standard of the Russian Federation GOST 30649 -99 "Alloys based on precious metals jewelry. Stamps." Gosstandart of Russia - M .: IPK Standards Publishing House, 1999).

This jewelry alloy has the same fineness and color as the main palladium alloy having a sample of 500, has high strength properties (Vickers hardness is more than 160), but contains nickel, which is an allergen and is not recommended for use in long-term products according to EEC directives contact with human skin.

The main objective of the invention is the replacement of nickel with another metal with a match in fineness and color with the main palladium alloy having a sample of 500, and while maintaining the required strength and technological properties for this grade of alloy, i.e. Vickers hardness not lower than 160.

To solve this problem, the proposed alloy based on palladium containing silver, additionally contains silicon and copper in the following ratio of components, wt.%:

palladium - 50.0-50.5;

silver - 38-40;

silicon - 0.1-0.2;

copper is the rest.

The choice of boundary values of the parameters of the components indicated in the claims is due to the following.

The copper content in the range of 9.3-11.9 wt.% Is optimal for replacing nickel in the alloy and provides a color gamut of the alloy.

The addition of silicon in the range of 0.1-0.2 wt.% Provides the necessary level of strength properties of the alloy — Vickers hardness not lower than 160. At a lower silicon content, the required strength level is not provided, and with increasing silicon content, ductility decreases, which negatively affects on the technological properties of the alloy in the manufacture of jewelry by casting and metal forming, as well as the alloy begins to darken, turns gray, i.e. jewelry properties are deteriorating.

Thus, there is a causal relationship between the hallmarks and the task at hand. Replacing nickel with copper and the additional introduction of silicon into a palladium-based alloy containing silver ensures optimal hardness, coincidence in fineness and color with the main palladium alloy having a sample of 500, which allows it to be used in jewelry making.

Thus, the inventive alloy, in comparison with the known one, satisfies the EEC directives, coincides in fineness and color with the main palladium alloy having a sample of 500, has the required level of mechanical properties, which allows it to be used in the manufacture of jewelry by metal forming and casting methods.

The alloy was obtained using a copper-silicon ligature containing 2 wt.% Silicon and the rest copper, and then introducing 10 wt.% Of this ligature into the melt of the main components of palladium and silver in an induction furnace in an atmosphere of inert gas (argon). The temperature range of the alloy was determined by differential thermal analysis. The composition of the alloy was controlled by quantitative chemical analysis. After casting, the alloy was subjected to homogenization annealing in an inert gas (argon) atmosphere.

To study the strength properties of the proposed alloy, hardness was determined using DM 8 V hardness testers, and the chemical composition was retested using an EVO 50 scanning electron microscope with an INCA 350 energy dispersive analyzer.

For comparison, table 1 shows the compositions of the inventive alloy, their strength properties in comparison with the known alloy. As can be seen from the tables, the claimed alloy in comparison with the known, due to the optimal combination of components in the alloy in the specified quantitative ratio, has the necessary level of strength properties.

Table 1 The compositions of the properties of the claimed and known alloys No. Alloy The chemical composition of the alloy, the mass fraction of the component,% Vickers hardness Palladium Silver Nickel Silicon Copper one claimed fifty 38 - 0.1 Ost. 161 2 claimed fifty 39 - 0.15 Ost. 162 3 claimed fifty 40 - 0.2 Ost. 163 four famous fifty 45 Ost. - - 161

Thus, the use of the inventive alloy in comparison with the prototype with the replacement of nickel by copper and with the additional introduction of silicon in the alloy based on palladium containing silver, ensures optimal hardness, coincidence in fineness and color with the main alloy of palladium having a sample of 500, which satisfies EEC directives and allows the use of alloy in the manufacture of jewelry.

Claims (1)

An alloy based on palladium 500 samples containing silver, characterized in that it additionally contains silicon and copper in the following ratio, wt.%:
palladium 50.0-50.5 silver 38-40 silicon 0.1-0.2 copper rest