BR102020026024A2 - PRE GOLD METALLIC ALLOY FOR JEWELRY - Google Patents

Abstract

PRE GOLD METALLIC ALLOY FOR JEWELRY. The present patent application proposes a metallic pre-alloy for use as a set of raw materials formulated for use in the preparation of a gold alloy intended for use in the manufacture of jewelry, which presents as some of its attributes allowing the gold alloy produced by using the pre-alloy proposed here, originates a metallic alloy that is not subject to staining or oxidizing in a dark way and that still presents great resistance to the risks of use, good flowability and yellow color with shades that can be adapted to a variation according to the addition of additives and low melting point that facilitates casting with stones. The pre-alloy has a base alloy with the following composition: Cu in the proportion of 11.75%; Ag in the proportion of 11.75%; Ni in the proportion of 0.48%; Zn in the proportion of 1.0%; Go at the ratio of 0.02; and Au in the proportion of 75.0%.

Description

PRE GOLD METALLIC ALLOY FOR JEWELRY APPLICATION FIELD

[001] This patent application deals with a metallic pre-alloy for use in the production of gold alloy for use in making jewelry, thus integrating the field of jewelry in general.

PREAMBLE

[002] The present patent application proposes a metallic pre-alloy for use as a set of raw materials formulated for use in the elaboration of gold alloy intended for use in the manufacture of jewelry, which presents as some of its attributes allowing the gold alloy produced by using the pre-alloy proposed here, originates a metallic alloy that is not subject to staining or oxidizing in a dark way and that still presents great resistance to the risks of use, good flowability and yellow color with shades that can be suitable for a variation according to the addition of additives and reduced melting point that facilitates casting with stones.

STATUS OF THE TECHNIQUE

[003] Anyone involved in jewelry making must have an appreciation of the nature of the metals and alloys they work with, and understand how the alloying and processing of metals influence the microstructure and consequently their properties.

[004] The alloy composition, microstructure and processing history are interrelated and jointly influence its properties, whether chemical (eg corrosion and stain resistance), physical (eg density, color) or mechanical (eg strength, malleability, hardness). These, in turn, influence the manufacturability, performance and quality of the product.

[005] The first basic factor to appreciate is that the smallest particle of a chemical element is called an atom and that it is composed of a nucleus of protons and neutrons surrounded by a cloud of electrons orbiting the nucleus.

[006] The atoms of each chemical element are identical but different from other chemical elements in size and weight (mass) because they have different numbers of protons, neutrons and electrons. The chemical elements can be arranged in order of size and characteristics in what is known as the Periodic Table. Elements are arranged on the periodic table and ordered in ways that resemble and share characteristics.

[007] The second point to consider is that (almost) all metals and alloys are crystalline in the solid state, as are gemstones and minerals. Atoms are encased in a regular matrix in what we call a crystal lattice.

[008] The properties of metals and alloys depend on their chemical composition, their microstructure and processing history. All of them are interrelated. No matter its application, such as decorative objects such as statues, chandeliers, soap dishes, among others. In jewelry for the manufacture of pendants, rings, earrings, chains, castings, laminates, drawn wires, among others, and alloys used in civil construction hardware and even in the aerospace segment. Regardless of the process and its application, metal alloys are engineering materials and follow the law of science, physics, chemistry and metallurgy, regardless of their application. From the simplest adornment or decorative piece to a rocket piece, high performance alloy.

[009] The metallurgical properties of precious metals and how they are influenced by their composition in the formation of alloys in their microstructures, is of paramount importance to achieve excellence in the production of jewelry. What happens when we deform or work with them, and what happens when we anneale and melt the worked material? How can we get the best properties out of them, suitable for the processes we use?

[0010] The way atoms are grouped is important, as it influences their properties. For example, how easily they deform during rolling work, casting and other processes, and how ductile they are.

[0011] Interestingly, all four precious metals - gold, silver, platinum and palladium - are Face Centered Cubic Cells (FCC). This structure is the one that most accepts being deformed and the most ductile. At the other extreme, metals such as zinc, magnesium and ruthenium have a hexagonal crystal structure (CPH).

[0012] In practice, real metals and alloys are composed of many small crystals - or grains as metallurgists call them. They are polycrystalline, with each crystal (or grain) arranged in different directions (Figure 1). Because of this, the atoms do not fit perfectly into the crystal structure creating boundaries between them (see Figure 2).

[0013] Such boundary regions are known as crystal or grain boundaries, and these can be more fragile lines, and preferred locations for accumulations of impurities from alloy processing, which can therefore cause a weakening that facilitates rupture. As we will see later, the crystal or grain size directly affects the properties, ductility and malleability of the alloys. Therefore, it is a factor to try to be avoided and controlled in jewelry making. In a practical way, in a jewelry this can occur as porosity, cracks, points that are not well polished, among several other problems that make it impossible to achieve the final product with excellence.

• • Boa condutividade térmica e elétrica;
• • Alta refletividade da superfície (polimento ou brilho);
• • Maleável (boa ductilidade, capaz de ser fortemente deformada);
• • Pesado, ou seja, alta densidade; e
• • Força e dureza razoáveis.

[0014] Characteristics of pure metals (and alloys as well) include:

• • Good thermal and electrical conductivity;
• • High surface reflectivity (polishing or gloss);
• • Malleable (good ductility, capable of being strongly deformed);
• • Heavy, ie high density; and
• • Reasonable strength and hardness.

[0015] Some metals have low densities (eg magnesium, lithium, aluminum) and other elements such as non-metals such as carbon (graphite) have good thermal and electrical conductivity.

[0016] Gold, silver, platinum and palladium, in turn, have great mass and density, are ductile and malleable and also have good thermal and electrical conductivity.

[0017] When we talk about alloys, we mean a mixture of two or more elements. An alloy may contain one or more phases in its microstructure. These can be distinguished by differences in chemical composition and/or crystal structure. Steel consists of iron atoms interspersed with carbon atoms, which fills the reticular interstice of the atomic formation of the alloy, providing greater mechanical strength. Cast iron, in turn, without going through a forging or rolling process, has very low mechanical strength. It should be noted that the simple addition of carbon atoms together with iron completely transforms the mechanical characteristics of iron, which becomes an iron-carbon alloy, called steel, which has much more mechanical strength.

[0018] In general, pure metals tend to be soft and not as strong, so alloys with other metals allow us to manipulate properties - typically to increase hardness and strength, but also other properties like color, corrosion resistance, coefficient of thermal expansion , temperature stability and magnetic properties - to meet application requirements.

[0019] If we use a pure metal, as in the first figure, we will have a perfect lattice because the sizes of atoms are equal. Different metal atoms have different sizes (diameters), replacing silver atoms (or other alloy metal) in the original gold lattice causes a distortion of the crystal structure (Figures 3, 3A and 3B). When we deform a metal, layers of atoms in each crystal slide past each other in a complex way to accommodate the overall shape change we impose.

[0020] As we deform a metal, the sliding mechanisms cause the crystal to become less perfect with an increasing accumulation of defects known as displacements.

[0021] Table 1 lists some of the common metals used in jewelry alloys and some of their basic properties. It should be noted, for example, that the copper atom is much smaller than the gold atom, while the silver atom is slightly larger. As we will see shortly, alloying gold with copper has a greater effect on its strength and hardness than simply pure gold, and so does silver.

[0022] Knowing that adding other metals to gold and silver, turning them into an alloy, causes deformity in the crystalline lattice, however adding such elements, on the other hand, also brings positive points regarding their application for the jewelry manufacturing. The positives outweigh the negatives. In view of this, the art of the jeweler enters, who manipulates such alloys and metals, so that while some characteristics are lost, others are gained. Resulting in a final product of excellent quality, reaching the state of the art in the manipulation of metals for jewelry.

[0023] Below we will see some additives that can be placed and what characteristics such additives bring benefit to the strategic casting in jewelry. The following text provides a brief overview of metal alloys for jewelry, and additions of metals as additives and their characteristics when applied to alloys for jewelry. The numbers are given in percentage by weight, for example copper (Cu) is the only metal addition to make the silver alloy, which is used in jewelry called 925 sterling silver and comprises (92.5% by weight of Ag and 7.5% by weight of Cu).

[0024] For the 18k gold alloy 750 mm in 3N color, the alloy is composed of 75% Au, 12.5% Cu and 12.5% Ag, and corresponds to the most reddish coloration used in Europe. Copper and silver are directly related to the color of gold. When you add more copper than silver, the end result is rose gold, when you add more silver than copper, the result is a lighter yellow, used more often in Brazil.

[0025] The alloys make the metal more ductile and malleable, perfect for working. This is a simplistic and illustrative view of the composition of gold and silver alloys for knee braces, but working strategically, the alloy must be formulated according to the method, processing and model to be produced, such as wax casting method. lost, processing can be melting by torch, induction or by electrical resistive heating with closed chambers of controlled atmosphere or in atmospheric conditions and the model, which can be thick, medium, thin pieces, with different shapes and sizes.

[0026] Metals added to the gold base alloy in the form of additives, in small amounts, promote unique characteristics, adapting the material in a specific way for each work. For example, it lowers the melting point, makes the alloy resistant to scratches, protects from oxidation, makes the alloys more ductile, and so on. This leads to a wide range of applications, providing suitable specifications for each type of work, such as lamination, casting and other industrial jewelery processes.

[0027] Copper oxidizes easily, turning parts dark, oxide layers occur in castings during outdoor cooling or during reheating, for example in soldering. This also leads to surface oxidation problems and on some inner layers, which can be seen as gray, bluish or reddish areas on finished surfaces. Finally, copper also accelerates the tarnishing of silver and gold.

[0028] Zinc (Zn) is used at approximately 2.5% by weight. It reduces the surface tension of the cast material and, thus, increases the fluidity, facilitating the filling of the shape of the parts with great resolution and quality, in addition to reducing the surface roughness. Zinc, in turn, increases the fluidity and helps to fill the cavities of the pieces, providing rich details and also lowers the total melting points of the alloy, which promotes a casting in more favorable conditions for casting with stones, since the stones do not they are good conductors of temperature and in very high temperature conditions they can crack or burn.

[0029] Associated with silicon (Si), which has a great affinity for oxygen, much greater than that of copper, it oxidizes before copper, and silicon oxide, already a by-product of silicon bound with oxygen, creates a layer oxide transparent to the naked eye, which protects the castings and maintains the vivid colors of gold and silver. It helps to prevent the development of copper oxide which is dark.

[0030] Silicon (Si) is used at approximately 0.2% by weight. It has a stronger affinity for oxygen than silver, copper and zinc and therefore acts as a deoxidizer of the molten alloy. Silicon prevents the formation of copper oxide that are dark, almost black and promotes shiny layers of silicon oxide (SiO2) in the parts that are cast, maintaining the original color of the metals, in the case of gold a bright yellow and silver a white brillant. Alloys with a low level of silicon can be considered an excellent option that combines the benefit of the effects of deoxidation and a great protection against copper oxide, still presenting a great advantage compared to alloys without silicon in terms of ease of application. In practice, for casting models with stones already embedded in wax, once these pieces have been cast and turn black due to copper oxide, it is very difficult to remove the dark color because the stones make access to the metal impossible.

[0031] An alloy with a high level of silicon provides the parts with a copper oxide-free casting, so it is especially essential for casting with stones set in wax, for example, in pavé format, which is impossible to access the metal for later. clarification. It has the highest protection against discoloration phenomena under all conditions.

[0032] The best way to work with the alloy project of this patent is with closed system machines with inert gas protection, where there is no presence of oxygen, or it is almost null. With a controlled atmosphere system, it is possible to avoid or dose to taste the amount of specific gases with oxygen, nitrogen, argon and hydrogen that mixed with each other at different levels and proportions interact with the various components of the alloy, in order to protect the part that will be melted thus avoiding stains and keeping the piece clear.

[0033] As silver and gold have low reactivity to oxygen, the copper present in the traditional alloy in contact with oxygen, both at the time of casting, and later in the use of the finished piece, forming various types of bonds with ambient oxygen. Such bonds usually occur in the formation of its Cu2O CuO and other several variations.

[0034] In processing, a surface layer is created, subsequent and adjacent, which in turn end up sealing the grain boundary, thus preventing adverse reactions with oxygen, sulfur gases and others around the medium from penetrating and reacting with the alloy forming dark colors.

[0035] About Grain Reducers: Additions in small amounts in the range of one part per million of high melting point metals such as iridium and ruthenium are added to create smaller grains and refine the structure of the molten metal. Smaller grains are essential to improve mechanical and structural strength. They are also important for increasing overall ductility and malleability, and for preventing the orange peel effect on workpiece surfaces.

[0036] As already mentioned, pure metals solidify at a fixed temperature; for example, gold solidifies at 1064°C/1947°F and silver at 962°C/1763°F. Most alloys, on the other hand, solidify over a range of temperatures: liquid is the temperature above which the alloy is completely melted; solid is the temperature at which solidification is complete and therefore below this temperature the alloy is completely solid (there are some exceptions such as eutectic points which also solidify at a fixed temperature like pure metals). Between liquid and solid, alloys comprise some liquids and other solids, generally known as the "soft" or pasty state. The solidification characteristics and the resulting structure are influenced by the temperature difference between the liquid and the solid and the general phase diagram of the alloy system.

[0037] In the diagram of figure 5 we clearly see the phases of the silver/gold alloy, the upper part of the diagram corresponds to the liquid. The bottom of the diagram to the complete solid and the dashed curve corresponds to the solid/liquid phase, "pasty".

[0038] Understanding the solidification process helps to understand the atomic structural properties of liquids and how atoms coalesce to form solid material. The liquid state comprises mobile atoms in a dynamic, unstructured state. Some atoms come together briefly to form a small cluster, but they break down quickly.

[0039] As we cool a liquid (molten metal in our case), small clusters of atoms clump together and stick together to form a nucleus. Nuclei formation tends to occur in preferred locations, such as a mold wall or in particulates such as impurity inclusions, but can occur randomly. As the temperature drops, more atoms join the small, stable clusters of atoms that comprise the nuclei in a structured way that is the crystal structure of that metal or alloy. These are the embryonic crystals that make up our alloy and a grain results.

[0040] Iridium and ruthenium, being high melting point metals and insoluble in the alloy, act as artificial precipitators in the formation of grains, they induce nucleation and precipitation in crystals of atoms once in liquid form. This results in a solid alloy with more grains and smaller grains.

[0041] In figures 6 and 7 we see the differentiation, in an alloy, with grain reducer and without grain reducer applied. Figure 7 shows much larger grains, while 6 with grain reducer additives presents much smaller grains that collaborate for the entire jewelry process.

OBJECTIVES OF THE INVENTION

[0042] This invention patent application aims at a GOLD METALLIC PRE ALLOY FOR JEWELRY that, when added to gold, allows obtaining a final product (gold alloy) that is not subject to the problems of analogous gold alloys, that is, the fact that such alloys can show stains and oxidation in a dark way and that they also present, as advantages, a great resistance to the risks of use, good flowability and that can be adapted to a color variation with the addition of additives and reduced melting point which facilitates casting with stones.

DESCRIPTION OF THE FIGURES

[0043] This patent application will be described in detail with reference to the drawings listed below, in which:
Figure 1 illustrates a schematic view that depicts the crystalline structure (grains) of a metal alloy depicted by way of example;
Figure 2 illustrates another representation of the structure of a metallic alloy, where the "grain boundary" region between two portions of the metallic alloy can be observed;
Figures 3, 3A and 3B illustrate, respectively and schematically, three metallic structures, where the first (figure 3) represents a pure metal, the second (figure 3A) represents an alloy, where a metal with a smaller atom is introduced, while the third (figure 3B) represents an alloy, where a metal with a larger atom is introduced;
Figure 4 illustrates a graph similar to that depicted in Figure 4, where, however, a surface of a gold piece with the alloy proposed in the present patent application is shown;
Figure 4A depicts a graph, where it is shown, figuratively, how a surface of a gold piece with a common alloy reacts in an environment with oxygen, and several other gases that comprise the atmosphere during the casting process due to the increase temperature and reactivity with atmospheric gases. Because of such reactions with ambient air the surface of the part is structurally altered creating more pores and roughness, the characteristic property of copper oxide is dark, thus making the surface stained;
Figure 5 illustrates a graph, where a phase diagram is depicted that demonstrates, according to the percentage of each material and temperature, the physical state of the alloy, which can vary from solid, liquid and solid/liquid, in this specific case a diagram of silver and gold; and
Figures 6 and 7 portray metallographic images of two metallic alloys, where figure 7 depicts an alloy with grain-reducing additives that presents much smaller grains that collaborate for the entire jewelry process, while figure 6 depicts a metallic alloy without a reducer. of grain applied and therefore, said alloy has much larger grains.

DETAILED DESCRIPTION OF THE INVENTION

[0044] This patent application proposes a pre-alloy of gold that has as positive technical characteristics the fact that when added to gold to form a gold alloy, it results in an alloy resistant to oxidation, resistant to internal stains, resistant to scratch resistant, resistant to dents of the pieces in daily use, has a low melting point, is ideal for casting with gems set in wax, does not require post-casting chemical treatment, has a yellow color with shades that can be adapted to a variation according to the addition of the additions.

[0045] The pre-alloy proposed here is particularly suitable for casting.

[0046] Alloy for gold for the manufacture of cast jewelry that require finishes with plastic morphological alteration and for casting with natural stones such as diamond, ruby, sapphire and emerald.

[0047] This patent application deals with a base alloy and two variant alloys, as well as three additives, and both the alloys and the additives will be defined in detail and explained below.

[0048] The base alloy presents, as its main characteristic, the excellent ductility, which allows great changes after processing, such as: rolling, drawing, stretching, bending, kneading and etc. It also has excellent plastic characteristics. In addition to low melting point for casting with natural stones and zirconia.

[0049] The base alloy contains iridium, an artificial grain precipitator, facilitates the formation of smaller grains, improving the plasticity and ductility of the finished alloy.

[0050] The base alloy in question also presents excellent resistance to scratches and knocks, as well as excellent polishing quality, it acquires an exceptional shine due to the additives that make up the alloy.

[0051] The pre-alloy object of this patent application, with regard to its base alloy, presents the substances listed below in the following proportions, as shown in table 2:

[0052] As previously mentioned, the pre-alloy object of this patent application presents a variant, which offers great antioxidant protection, provides an oxide-free function in the most adverse conditions, even without protection from inert gases, in a closed chamber being melted. directly with a blowtorch and oxygen exposed to the atmosphere. This alloy offers an oxide-free casting, which improves the surface of the parts, making the finishing process much easier, as it requires little sanding and does not require post-casting chemical treatment.

[0053] This alloy also provides for the casting of natural and synthetic gemstones in an open casting system as it has antioxidant protection, allows its use by professionals with few resources who do not have high-tech machinery available, with an inert gas protection system , with a closed system you can enjoy the casting process with stones already engraved in the coating molds.

[0054] The pre-alloy object of this patent application, with regard to its variant, presents the substances listed below in the following proportions, as shown in table 3:

[0055] The pre-alloy object of this patent application also has a second variant, which offers great antioxidant protection, provides an oxide-free function in the most adverse conditions, even without protection by the action of inert gases, being melted directly with a torch and oxygen. This alloy offers an oxide-free casting, which improves the surface of the parts, greatly facilitating the finishing process, as it requires little sanding and does not require post-casting chemical treatment.

[0056] This alloy (second variant) also provides for the casting of natural and synthetic gemstones in an open casting system, since it has antioxidant protection, allows its use by professionals who do not have machinery with an inert gas protection system with a closed, being able to enjoy the casting process with stones already engraved in the coating molds and compared to the variation 1, it offers a smaller grain, facilitating the post-primary processing processes of the foundries, offering greater possibilities of work that involves controlled deformity of the castings such as bending , drawing, kneading, lamination and etc.

[0057] The pre-alloy object of this patent application, with regard to its second variant, presents the substances listed below in the following proportions, as shown in table 4:

[0058] The pre-alloy proposed here is combined with gold in the proportion of 75%/25%, where gold corresponds to 75% (3/4) and the pre-alloy corresponds to 25% (1/4), and of the 25% of the pre-alloy itself, a portion of 5% (1/5) corresponds to the volume of the pre-alloy (basic alloy or its variant), while 20% (4/5) corresponds to the alternative addition of the additive component " A" or additive "B".

[0059] Additive component "A" acts to turn the alloy color into a more yellowish, light yellow color.

[0060] This additive allows the customer to choose a unique color pattern to be implemented in their line, giving a unique signature to their pieces, thus marking the brand with a personalized color, offering a highlight in relation to competitors in the market.

[0061] This additive also follows the standards of oxygen protection, grain reducing additive, low melting temperature (facilitating stone casting), scratch protection and grain reducing.

[0062] This additive must be added to pure gold, in a proportion of 25% of additive agent "A" described herein and 75% of pure gold, which comprise the 18k gold alloy 750mm.

[0063] The additive component "A" object of this patent application presents the substances listed below in the following proportions, as shown in table 5:

[0064] Additive component follows the same characteristics of the additive component "A", but instead of turning the color to light yellow, this component tries to bring out the reddish tones.

[0065] The additive component "B" object of this patent application presents the substances listed below in the following proportions, as shown in table 6:

[0066] This patent application also provides for the use of a compensating Additive, called additive component "C", which is an antioxidant agent, which can be added during prolonged use. For a more accentuated antioxidant action, in tailor-made garments, according to the application need of each customer or even for just replacement of these components in alloys already prepared with gold in order to replace the agents that keep the alloy free. of oxides.

[0067] The additive component "C" object of this patent application presents the substances listed below in the following proportions, as shown in table 7:

Claims (8)

"PRE METALLIC GOLD ALLOY FOR JEWELRY", which is characterized by providing a base alloy with the following composition: Cu in the proportion of 11.75%; Ag in the proportion of 11.75%; Ni in the proportion of 0.48%; Zn in the proportion of 1.0%; Go at the ratio of 0.02; and Au in the proportion of 75.0%. "GOLD METALLIC PRE ALLOY FOR JEWELRY", according to claim 1, characterized by presenting a first variant with the following composition: Cu in the proportion of 11.90%; Si in the proportion of 0.35%; Ag in the proportion of 11.25%; Ni in the proportion of 0.48%; Zn in the proportion of 1.0%; Go in the proportion of 0.02%; and Au in the proportion of 75.0%. "GOLD METALLIC PRE ALLOY FOR JEWELRY", according to claim 1, characterized in that it presents a second variant with the following composition: Cu in the proportion of 11.50%; Si in the proportion of 0.10%; Ge in the proportion of 0.40%; Ag in the proportion of 11.50%; Ni in the proportion of 0.48%; Zn in the proportion of 1.0%; Go in the proportion of 0.02%; and Au in the proportion of 75.0%. "GOLD METALLIC PRE ALLOY FOR JEWELRY", according to any one of claims 1 to 3, characterized in that it may include an additive component "A" with the following composition: Si in the proportion of 0.10%; Ge in the proportion of 0.30%; Ag in the proportion of 23.10%; Ni in the proportion of 0.48%; Zn in the proportion of 1.0%; Go in the proportion of 0.02%; and Au in the proportion of 75.0%. "GOLD METALLIC PRE-ALLOY FOR JEWELRY", according to any one of claims 1 to 3, characterized in that it may include an additive component "B" with the following composition: Si in the proportion of 0.20%; Ge in the proportion of 0.20%; Cu in the proportion of 23.10%; Ni in the proportion of 0.48%; Zn in the proportion of 1.0%; Go in the proportion of 0.02%; and Au in the proportion of 75.0%. "GOLD METALLIC PRE ALLOY FOR JEWELRY", according to any one of claims 1 to 3, characterized in that it may include an additive component "C" with the following composition: Si in the proportion of 1.00%; Ge in the proportion of 1.00%; Cu in the proportion of 23.00%; and Au in the proportion of 75.0%. "GOLD METALLIC PRE ALLOY FOR JEWELRY", according to any one of claims 1 to 3, characterized in that the proposed pre-alloy is combined with gold in the proportion of 75%/25%, where gold corresponds to 75% ( 3/4) and the pre-alloy corresponds to 25% (1/4), and of the 25% of the pre-alloy itself, a portion of 5% (1/5) corresponds to the volume of the pre-alloy (basic alloy or its variant), while 20% (4/5) corresponds to the alternative addition of additive component "A" or additive "B". "GOLD METALLIC PRE ALLOY FOR JEWELRY", according to any one of claims 1 to 3, characterized in that the additive component "C" is an antioxidant agent and for acting as a replacement, gold pre alloy, of the substances Si, Ge , Cu and Au.

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