RU2352660C2 - Alloy on basis of palladium - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: alloy on the basis of palladium contains components in a following ratio, wt %: palladium 85.0-85.5, silver 0.01-15, copper 0.01-13, gold 0.01-2, molybdenum 0.01-1, rhodium 0.01-1. Alloy can be used for manufacturing of jewelry.

EFFECT: reduction of alloy melting temperature, extension of alloy range of application while manufacturing of jewelry and receiving of aesthetic properties of alloys in jewelry.

5 tbl

Description

The present invention relates to the field of metallurgy of palladium-based alloys for the manufacture of jewelry.

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. This alloy has the following characteristics: thermal expansion of 0.66-0.72% at 500 ° C, melting point 1400 ° C, Vickers hardness more than 150, tensile strain more than 6% (US 4387072, 06/07/1983, C22C 5/04 )

However, such an alloy with high strength characteristics, has a high melting point, and also contains cobalt. Cobalt is a commonly recognized toxic substance and is not recommended for use in jewelry alloys. Increased indium content will increase the hardness and brittleness of the alloy.

The composition closest to the invention is an alloy based on palladium, containing by weight, in%: palladium - 85, silver - 12.5-13.5 and nickel - the rest (State standard of the Russian Federation GOST R 51152-98 "Alloys based on precious metals jewelry. Stamps. Gosstandart of Russia, Moscow, IPK Standards Publishing House, 1998, p. 4).

Such an alloy has a high melting point and also contains nickel. The high melting point makes it difficult to carry out the process of obtaining jewelry by casting methods and places high demands on the mold mass. Due to the non-optimal ratio of palladium-nickel components, the alloy has a low reflection coefficient. In addition, nickel according to EEC directives is not recommended for use in products that come into long-term contact with human skin.

The main objective of the invention, therefore, is to reduce the melting temperature, obtain the necessary range of mechanical properties that expand the scope of the alloy in the manufacture of jewelry (casting, rolling, drawing, stamping, chasing), and obtain aesthetic properties of the alloy in jewelry (color, reflective ability, non-toxicity).

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

palladium 85.0-85.5 silver 0.01-15 copper 0.01-13 gold 0.01-2 molybdenum 0.01-1 rhodium 0.01-1.

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 0.01-13 wt.% Is optimal for the replacement of palladium in the alloy and provides increased tensile strength.

The addition of molybdenum in the range of 0.01-1 wt.% Can be considered as modifying, grinding the grain of the alloy, which leads to an improvement in the quality of products obtained by casting and pressure processing.

Rhodium in the range of 0.01-1 wt.%, Along with the manifested modifying effect, is a strengthening additive that increases the anticorrosion properties of the alloy, prevents the interaction of the alloy with the form mass and improves (brightens) the color scheme of the alloy.

Gold in the range of 0.01-2 wt.% Improves the ductility of the alloy, increases the anticorrosion properties when casting into the mold mass, and reduces the tendency to gas absorption.

In addition, the presence in the alloy of silver, gold and copper in the indicated amounts provides a decrease in casting temperature by 50-100 ° C.

The inventive alloy, thus, in comparison with the known one, is characterized by a lower melting point, optimal hardness, has a white color with a gloss similar to platinum, high reflectivity and has high plastic and strength properties, which allows it to be used in the manufacture of jewelry by processing methods metal pressure and casting.

The alloy was obtained by direct fusion of the main components in an induction furnace in an atmosphere of inert gas (argon). Modifying, anticorrosive and other additives were introduced into the melt immediately before casting. 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 deformability of the ingot, they were subjected to high-quality rolling without the use of intermediate annealing, then the obtained rods were annealed, and then the workpiece was dragged on a drum mill to a diameter of 0.3-0.4 mm using annealing. Elongation and tensile strength were determined on deformed specimens using an H5KS tensile testing machine.

The structure of the alloy samples at all stages of the heat and mechanical processing was analyzed by metallographic methods of investigation, while the microhardness and reflection coefficient in the visible wavelength range were determined (SPECORD-M40 device).

For comparison, table 1, 2 shows the compositions of the claimed alloys, their physico-chemical properties, as well as the reflection coefficient in comparison with known alloys. As can be seen from the tables, the claimed alloys in comparison with the known, due to the optimal combination of components in the alloy in the indicated quantitative ratio, have high reflectivity, improved physical and mechanical properties and lower melting points.

The properties of the proposed alloy shown in the tables allow to produce high-quality jewelry from it by casting and plastic deformation methods.

Table 1
The compositions of the claimed and known alloys No. Alloy The chemical composition of the alloy, the mass fraction of the component,% Palladium Silver Copper Nickel Gold Molybdenum Rhodium one claimed 85.0 2.98 10.0 - 2.0 0.01 0.01 2 claimed 85,2 2.0 10.0 - 2.0 0.3 0.5 3 claimed 85.5 11.69 2.0 - 0.01 0.3 0.5 four claimed 85.0 14.96 0.01 - 0.01 0.01 0.01 5 claimed 85.0 1.97 13.0 - 0.01 0.01 0.01 6 famous 85.0 12.5-13.5 - Ost. - - -

table 2
Properties of the claimed and known alloys No. Alloy Maximum melting point, ° С Hardness HV, kgf / mm ² σ _V , MPa δ,% To _neg ,% one claimed 1400 148 450.7 28 80 2 claimed 1380 131 384.8 34 77 3 claimed 1390 135 345.0 33 75 four claimed 1400 127 382.2 26 78 5 claimed 1380 159 509.9 26 77 6 famous 1500 125 - - -

The results of studies conducted under industrial conditions for alloys No. 1-3 with different chemical composition in the claimed range of component ratios are presented in Table 3-5, where the following are listed as mechanical characteristics of the alloys: σ _in - temporary tensile strength; δ is the elongation. An analysis of the spectra for finely ground samples of the proposed alloys showed that in the visible region the reflection coefficient was from 0.75 to 0.82.

Claims (1)

A palladium-based alloy containing silver, characterized in that it additionally contains gold, copper, molybdenum and rhodium in the following ratio of components, wt.%:
palladium 85.0-85.5 silver 0.01-15 copper 0.01-13 gold 0.01-2 molybdenum 0.01-1.0 rhodium 0.01-1.0