Gold solder for silk enamel jewelry

Abstract

The gold solder comprises a high-temperature-level solder, a medium-temperature-level solder and a low-temperature-level solder, and the high-temperature-level solder comprises 0.1%-1.5% of silver, 0.5%-4.0% of copper, 0.2%-3.0% of zinc, 0.01%-0.5% of indium, 0.01%-0.3% of tin, 0.01%-0.1% of rare earth and the balance gold; the medium-temperature-level solder comprises 0.1%-1.5% of silver, 3.6%-8.0% of copper, 0.5%-4.46% of zinc, 0.03%-2.0% of indium, 0.01%-0.5% of tin, 0%-0.5% of germanium, 0.01%-0.1% of rare earth and the balance gold. The low-temperature-level solder comprises 0.1%-1.5% of silver, 3.0%-6.0% of copper, 2.5%-11.0% of zinc, 0.1%-1.0% of indium, 0.01%-1.0% of tin, 0%-0.5% of germanium, 0.01%-0.1% of rare earth and the balance gold.

Description

Technical Field

[0001] The invention relates to the technical field of jewelry solders, in particular to a gold solder for filigree enamel jewelry. Background Art

[0002] Welding is an essential process in gold jewelry production, whether for component assembly or defect repair. Depending on whether solder is used, gold jewelry welding can be categorized as bulk welding or brazing. The main bulk welding methods include laser spot welding, plasma welding, and fusion welding (commonly known as water-flow welding). Laser spot welding can use a welding wire that is consistent with the underlying material, or it can be done without a wire, fusing the welded parts directly. Plasma welding, however, requires no wire and fuses the welded parts together under the action of plasma. These two welding methods are only suitable for small pieces or small, non-stressed areas. Welding large areas results in noticeable welds, severely impacting the appearance. They are not suitable for gold jewelry, and their welds lack strength and are prone to breaking or falling apart. Fusion welding involves directly melting two or more gold jewelry parts at the joint to achieve the desired connection. Because there is no solder or temperature difference, this process is difficult to perform. A slight mismatch in the heat can cause the workpiece to melt and deform, damaging the structure and appearance of the gold jewelry. Solder brazing refers to the use of solder to weld gold parts. Since solder is used for welding, only the solder needs to be melted during welding. The melting point of solder is generally lower than that of gold. Therefore, brazing will not cause melting and deformation of gold jewelry in adjacent parts. Compared with fusion welding, solder brazing has a wider range of applications.

[0003] Filigree craft, originating from the gold and silver inlay techniques of the Spring and Autumn Period and the Warring States Period, is a long-standing traditional Chinese craft, primarily used in the production of imperial jewelry. Filigree reached a high artistic level during the mid-to-late Ming Dynasty, particularly renowned for its weaving and stacking techniques. It also frequently incorporates kingfisher feather inlays, creating a resplendent effect. Filigree, a traditional gold and silver craft with a most representative Chinese element, was inscribed on the National Intangible Cultural Heritage List in June 2008.

[0004] The basic process of filigree craftsmanship is to first roll gold and silver bars into thin rods, draw them into filaments, and then twist two or more strands of wire into various patterned filigrees. When making filigree jewelry, tweezers or pliers are used to pinch the filigree into various patterns, which are then filled or stacked in the prescribed pattern to form various shapes. A small sieve is used to sift the powdered solder, and the resulting patterns are welded together. Filigree jewelry is often composed of several filigree components, which need to be assembled into a whole through assembling. After assembling, they need to be fixed by welding. However, for complex shapes, some parts are difficult to weld after assembling (commonly known as "not resistant to fire"), and the blanks are easily welded when the firepower is increased.

[0005] Gold filigree jewelry requires welding to form. The numerous and widely distributed welds make laser welding, plasma welding, or water-melting welding impossible. Brazing with solder is the only option, and this process must be repeated multiple times. This makes welding challenging and places high demands on the solder used. The solder used to connect the various components is an integral part of the filigree jewelry. As a precious metal piece, it must maintain the overall properties of the jewelry, most importantly ensuring its preciousness, color harmony, and chemical and mechanical stability—all fundamental requirements for the solder. Furthermore, filigree jewelry, especially those with more complex structures, requires separate fabrication of several components, which are then assembled and welded together in stages. Using the same solder can cause previously welded parts to re-melt during subsequent welding, leading to disintegration and collapse of the workpiece. Therefore, solders with different melting points, such as high, medium, and low, must be formulated. The appropriate solder must be selected based on the specific components and production steps of the filigree jewelry, and the solder must be powdered for easy welding.

[0006] For a long time, filigree and enamel crafts have often been combined to enhance the product's craftsmanship and artistic value. Enamel requires high-temperature firing to form a vitreous glaze, typically between 760 and 800°C. When combined with filigree crafts, to prevent melting and cracking at the filigree welds during enamel firing, enamel glazes with lower firing temperatures are typically used. However, firing temperatures typically need to be controlled between 630 and 650°C. This presents significant challenges for filigree welds. If the melting point of the solder is too high, weld quality is difficult to maintain and may even cause burns to the workpiece. If the melting point is too low, the solder cannot withstand the high temperatures of enamel firing, resulting in damage to the weld. To address this issue, compromises often have to be made during production: the workpiece is disassembled into several components, the components requiring enamel firing are fabricated separately, and then assembled with the other components after the enamel is fired. However, this significantly increases production complexity and cost, and also compromises the overall product quality.

[0007] Welding is one of the most fundamental forming processes in gold filigree production. Due to the numerous components of gold filigree products, a single welding process is difficult, requiring multiple welding steps. The properties of the solder are crucial for the quality of the filigree process. In traditional filigree production, the chemical composition of the flux used for high-temperature welding is typically: 70-85% gold, 10-20% silver, 5-10% copper, and 0-3% zinc and cadmium. The flux has a melting point of 750-850°C. It contains the toxic element cadmium and is gradually being phased out. Traditional gold solder used for medium-temperature welding typically has a chemical composition of: 50-65% gold, 20-30% silver, 10-15% copper, 3-5% zinc, and 2-5% tin. The alloy has a melting point of approximately 650-750°C and offers excellent fluidity, making it suitable for fine filigree welding. Traditional low-temperature gold solder typically has a chemical composition of 78-82% gold and 18-22% tin. Small amounts of indium and boron can be added to further lower the melting point, resulting in a melting point of 280-350°C, making it suitable for thin wire welding. Traditional gold filigree solders often contain high levels of the harmful element cadmium, and the highly toxic arsenic trioxide (commonly known as "arsenic") is often used during melting and casting. To meet the demands of modern gold jewelry, traditional gold filigree solders face challenges in ensuring gold purity, ensuring environmental friendliness, and adaptability to enamel processes.

[0008] Some researchers have conducted research and exploration on solder for gold filigree jewelry and have proposed corresponding intellectual property protection. For example, Chinese patent CN201510123456.7 discloses a gold-based solder and its preparation method. Its chemical composition is 70% to 85% Au (gold), 10% to 20% Ag (silver), and 5% to 10% Cu (copper). A trace amount of In (indium) or Sn (tin) (≤ 2%) can be added to improve wettability. The solder has a melting point of 350 to 400°C and is suitable for fine gold filigree welding. Chinese patent CN201810234567.8 discloses a gold-based alloy solder for precision welding of gold wire. Its alloy composition is: Au (gold) 60% to 75%, Ag (silver) 15% to 25%, Cu (copper) 5% to 15%, Sn (tin) 3% to 8%. Trace amounts of Ge (germanium) or Si (silicon) (≤1%) can be optionally added to refine the grains. The melting point of this solder is as low as 280 to 360°C, which is suitable for fine gold wire welding. Chinese patent CN201920345678.9 discloses a lead-free gold-based solder for gold filigree crafts. Its alloy composition (wt%) is: Au (gold) 65% to 80%, Ag (silver) 10% to 20%, Cu (copper) 5% to 12%, Sn (tin) 5% to 10%, and In (indium) 2% to 5%. This solder is lead-free, environmentally friendly, and RoHS-compliant. It has a melting point of 300 to 380°C and is suitable for welding gold filigree crafts. Chinese patent CN201710456789.0 discloses a gold-tin eutectic solder for gold filigree welding and its preparation method. Its alloy composition is Au (gold) 78% to 82% and Sn (tin) 18% to 22%. This alloy is a eutectic alloy with a melting point of 280°C and is suitable for high-precision gold filigree welding and high welding strength. Chinese patent CN1055135A discloses a gold-based solder alloy for pure gold jewelry. Its chemical composition is: Au 94.5-98%, Zn 1.0-5.0%, Si 0.1-3.0%, Cu 0.1-3.0%, Ge 0.1-4.0%, Cd 1.0-4.3%, and Ag 0.1-3.0%. This alloy contains the harmful element cadmium, has an excessively wide composition range, and lacks a solder gradation design tailored to different welding stages, making it difficult to achieve the desired results in production. U.S. Patent US3892564A discloses a gold-based solder alloy with a typical composition of 75% gold, 10% gallium, and 15% copper. The alloy's color is too low to meet the color requirements of filigree jewelry. Furthermore, the high gallium content results in excessively large crystal spacing in the solder, making it difficult to maintain the mechanical strength and density of the weld. U.S. Patent No. 4,014,690 discloses a gold-based solder alloy for dentistry and jewelry, the composition of which is 60-70 Au, 0-10 Pt, 0-10 Pd, 10-25 Cu, 5-10 Ga, and 0-0.01 Ir.U.S. Patent No. 3,892,564 also discloses a gold-based brazing alloy for dental and jewelry applications, consisting of 1-10 Ga, 0-25 Cu, 0-33 Ag, 0-10 Zn, and the remainder Au. Japanese Patent Laid-Open No. 58-151992 and its equivalent, U.S. Patent No. 4,444,719, also disclose a gold-based brazing alloy consisting of 50-67 Au, 3-5 Ge, and the remainder Ag and Cu. Due to their low gold content, these alloys fail to meet jewelry quality requirements and are difficult to use for multi-stage brazing of complex jewelry.

[0009] In general, there are still some problems with existing gold wire solders:

[0010] (1) The gold quality cannot be guaranteed. The gold content of solder is generally low, and some even have a gold content of only 60%. This can easily affect the overall quality of the product, resulting in the risk of the product not meeting the quality standards. In addition, the color contrast between the solder and the base material is large.

[0011] (2) There are no requirements for multiple welding processes of gold filigree jewelry, and there is no systematic design of solder grading for graded welding. Some patents provide a very wide range of compositions, which lacks applicability and certainty for actual production.

[0012] (3) There is no specific design of the gold filigree solder grading based on the welding requirements of filigree enamel jewelry. Since the enamel firing temperature cannot be too low, the minimum melting temperature of the gold filigree solder must not be lower than the enamel firing temperature, otherwise it will cause the welded parts to disintegrate.

[0013] (4) Some gold wire solders have poor welding performance and poor solderability. They are not easy to disperse during welding and are prone to burning the workpiece due to heated welding. Some solders use a large amount of low-temperature metals such as tin and gallium to lower the melting point. There are problems such as easy oxidation of the welding position to form impurities, low welding strength, and difficulty in electroplating the welding position.

[0014] (5) Although some gold wire solders improve soldering performance, they still contain toxic and harmful elements such as cadmium and cannot meet green environmental protection requirements. Summary of the Invention

[0015] To overcome the shortcomings of the existing technology, the present invention provides a gold solder for filigree enamel jewelry to address the aforementioned issues. Focusing on the process requirements of gold filigree jewelry production, particularly the specificities of gold filigree enamel jewelry production, the present invention optimizes the solder formula for high, medium, and low temperature soldering for gold filigree enamel jewelry. The solder's maximum liquidus temperature is controlled to not exceed 990°C, and its minimum solidus temperature is not less than 700°C, with a soldering temperature gradient of 60 to 120°C. This ensures good controllability, with a color purity of not less than 95% for the high-temperature solder, not less than 22K (91.7%) for the medium-temperature solder, and not less than 85% for the low-temperature solder. This significantly reduces the risk of insufficient color in filigree products. The graded solder offers excellent welding performance and corrosion resistance, and its color closely resembles pure gold. It can meet the diverse solder preparation processes and facilitates the integration of filigree and enamel processes.

[0016] The present invention is implemented by the following technical solutions:

[0017] A gold solder for filigree enamel jewelry, including high-temperature solder, medium-temperature solder, and low-temperature solder. The high-temperature solder is used for the first or initial welding of welded parts, the medium-temperature solder is used for intermediate welding after the welded parts are welded with the high-temperature solder, and the low-temperature solder is used for final assembly welding after the welded parts are welded with the medium-temperature solder.

[0018] Among them, the high temperature grade solder includes the following components in mass percentage:

[0019] Silver 0.1-1.5%, copper 0.5-4.0%, zinc 0.2-3.0%, indium 0.01-0.5%, tin 0.01-0.3%, rare earth 0.01-0.1%, the rest is gold, and unavoidable impurity elements;

[0020] Medium temperature grade solder includes the following components in mass percentage:

[0021] Silver 0.1-1.5%, copper 3.6-8.0%, zinc 0.5-4.46%, indium 0.03-2.0%, tin 0.01-0.5%, germanium 0-0.5% (including 0), rare earth 0.01-0.1%, the rest is gold, and unavoidable impurity elements;

[0022] Low temperature grade solder includes the following components in mass percentage:

[0023] Silver 0.1-1.5%, copper 3.0-6.0%, zinc 2.5-11.0%, indium 0.1-1.0%, tin 0.01-1.0%, germanium 0-0.5% (including 0), rare earth 0.01-0.1%, and the rest are gold and inevitable impurity elements.

[0024] Among the above materials, silver is pure silver with a content of 99.95wt% or more, copper is pure copper with a content of 99.95wt% or more, zinc is pure zinc with a content of 99.95wt% or more, indium is pure indium with a content of 99.95wt% or more, tin is pure tin with a content of 99.95wt% or more, and germanium is pure germanium with a content of 99.95wt% or more.

[0025] In the present invention, when developing gold solder for filigree enamel jewelry, the basic ideas followed are:

[0026] (1) Taking into account the structural characteristics of filigree enamel jewelry products and their manufacturing process, an overall design is carried out from a system perspective, and the solder is divided into three levels: high temperature, medium temperature, and low temperature. The high temperature solder is used for the primary structural welding of the product, the medium temperature solder is used for the secondary structural welding of the product, and the low temperature solder is used for the decorative welding and final repair welding of the product. The soldering temperatures of the three levels are approximately 100 to 120 ° C apart, which can ensure that the previous welding position is not damaged by the remelting of the subsequent welding, and has a wide temperature range, which is convenient for operation and control.

[0027] (2) The brazing temperature of the high-temperature grade solder should be controlled at 980-1010℃. Under the premise of ensuring the safety of the base material, sufficient temperature space should be reserved for medium-temperature and low-temperature grade soldering. At the same time, the gold content of the high-temperature grade solder should not be less than 95% under the premise of meeting the welding performance requirements to ensure that the quality of the filigree products meets the standards.

[0028] (3) The brazing temperature of the medium-temperature solder is controlled at 880-910°C, which will not cause the high-temperature weld to remelt and spread, and will also leave enough temperature space for low-temperature welding. Under the premise of meeting the welding performance requirements, the gold content of the medium-temperature solder is controlled to be no less than 22K to ensure that the color of the filigree product meets the standards.

[0029] (4) The brazing temperature of the low-temperature solder is controlled at 760-790°C, which will not cause the medium-temperature solder to remelt and spread, and will also leave enough temperature space for enamel firing. Under the premise of meeting the welding performance requirements, the gold content of the low-temperature solder is controlled to be no less than 85%, ensuring that the color of the filigree product meets the standard. After acid treatment, the color of the weld is close to that of the base material.

[0030] (5) After the weld is treated with acid, its color is close to that of the base material.

[0031] (6) The solder has good wettability, gap filling and brazing processability on the jewelry substrate and has good chemical stability.

[0032] (7) The welding parts have sufficient strength, corrosion resistance and oxidation resistance.

[0033] (8) The solder does not contain toxic elements such as Cd and As, and is green and environmentally friendly.

[0034] The specific ideas are:

[0035] (1) High temperature grade solder

[0036] High temperature grade solder is used for the first or initial welding of weldments and is the main load-bearing factor of filigree products. The formulated high temperature grade solder should have a high melting point, good fusion welding performance, high strength performance and excellent ductility, and the welded joint can resist impact and vibration.

[0037] (2) Medium temperature solder

[0038] Medium-temperature solder is used for welding in the middle links of weldments, usually involving one or more welding operations. It requires that its melting point be 100 to 120°C higher than that of high-temperature solder. At the same time, the melting temperature interval of the solder is small and the fusion welding performance is good.

[0039] (3) Low temperature solder

[0040] Low-temperature solder is used for the final assembly welding of weldments, which usually involves one or more welding operations. It requires that its melting point be 100 to 120°C higher than that of medium-temperature solder. At the same time, the melting temperature interval of the solder is small and the fusion welding performance is good.

[0041] Based on the above considerations, the present invention optimizes the solder formula for high-temperature, medium-temperature, and low-temperature welding, controlling the maximum liquidus temperature of the solder to no more than 990°C and the minimum solidus temperature to no less than 700°C, with a welding temperature gradient of 60 to 120°C. This provides good controllability, with the color quality of the high-temperature solder no less than 95%, the color quality of the medium-temperature solder no less than 22K (91.7%), and the color quality of the low-temperature solder no less than 85%, significantly reducing the risk of insufficient color quality in filigree products. The graded solder has excellent welding performance and corrosion resistance, and its color is close to that of pure gold. It can meet the needs of different solder preparation processes and enables the integration of filigree and enamel processes with operability.

[0042] Furthermore, the total content of the unavoidable impurity elements does not exceed 0.1%.

[0043] Furthermore, the rare earth is one or more of cerium, yttrium, lanthanum, neodymium, and gadolinium.

[0044] Among the above materials, cerium is pure cerium with a content of 99.95wt% or more, yttrium is pure yttrium with a content of 99.95wt% or more, lanthanum is pure lanthanum with a content of 99.95wt% or more, neodymium is pure neodymium with a content of 99.95wt% or more, and gadolinium is pure gadolinium with a content of 99.95wt% or more.

[0045] Furthermore, the color purity of the high-temperature grade solder is not less than 95%, the color purity of the medium-temperature grade solder is not less than 91.7%, and the color purity of the low-temperature grade solder is not less than 85%.

[0046] Furthermore, the highest liquidus temperature of the solder does not exceed 990°C, the lowest solidus temperature is not lower than 700°C, and the soldering temperature difference is 60-120°C.

[0047] Furthermore, the liquidus temperature of the high temperature grade solder is 960-990°C.

[0048] The present invention sets the brazing temperature of high-temperature solder at 980-1010°C. A superheat of 20-30°C during welding ensures smooth flow of the solder liquid. The liquidus temperature is set at 960-990°C, creating an 83-53°C difference between the soldering temperature and the melting point of pure gold. This ensures sufficient operating space during soldering and prevents melting and collapse of the substrate structure. To improve the solder's color matching, welding performance, processing performance, physical properties, and corrosion resistance, the present invention utilizes a synergistic effect of multiple alloying to achieve a crystallization interval of no more than 50°C. The solder achieves a color of over 95%, excellent welding performance and oxidation resistance, a color close to that of pure silver, and meets the preparation process and mechanical property requirements of different solder forms.

[0049] Furthermore, the liquidus temperature of the medium-temperature solder is 860°C to 885°C, and the gold content of the medium-temperature solder is not less than 91.7%, wherein the brazing temperature is 875°C to 895°C.

[0050] Furthermore, the liquidus temperature of the low-temperature solder is 730°C to 760°C, and the gold content of the low-temperature solder is not less than 91.7%. The brazing temperature is controlled at 760°C to 790°C.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] The gold solder for filigree enamel jewelry of the present invention is graded into three levels: high temperature, medium temperature, and low temperature according to the welding temperature. The graded solder has excellent welding performance and oxidation resistance, a color close to that of pure gold, and can meet the preparation process and mechanical property requirements of different solder forms. DETAILED DESCRIPTION

[0053] The present invention will be further described below in conjunction with specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0054] Example 1

[0055] A gold solder for filigree enamel jewelry, including high-temperature solder, medium-temperature solder, and low-temperature solder. The high-temperature solder is used for the first or initial welding of welded parts, the medium-temperature solder is used for intermediate welding after the welded parts are welded with the high-temperature solder, and the low-temperature solder is used for final assembly welding after the welded parts are welded with the medium-temperature solder.

[0056] Among them, the chemical composition of (1) high temperature grade solder is: 0.49% silver, 3.92% copper, 0.48% zinc, 0.02% indium, 0.03% tin, 0.01% cerium, and the rest is gold and inevitable impurities.

[0057] Testing has shown that the solder has a color purity exceeding 95%, a liquidus temperature of 980°C, a crystallization interval of 47°C, good fluidity, a wetting angle of 25° with the pure gold substrate, and no sagging. Within the common gold filigree gap size (0.05-0.15mm), the soldering rate within the gap reaches over 95-96% thanks to gravity and capillary forces. The color value L* is 84.1, the chromaticity a* value is 7.2, and the b* value is 31. Traditional high-temperature gold filigree solder has a color value of approximately L*84.5, a*5.7, and b*28.6. Compared to the color values ​​of pure gold (L*85.5, a*8.8, and b*33.5), the color contrast of traditional gold filigree solder is large, with a noticeable white and silvery hue. The color of the solder of the present invention is basically close to that of pure gold. After acid treatment after welding, the color difference between the weld and the substrate is slightly discernible to the naked eye. After immersion in artificial sweat at a pH of 6.5 for 8 hours, the color difference of pure gold is approximately 0.25, while that of the solder of the present invention is approximately 0.8, and that of conventional gold wire solder is 2.2. Therefore, the solder of the present invention exhibits excellent sweat corrosion resistance, significantly superior to conventional gold wire solder and substantially close to that of pure gold. The solder exhibits a single face-centered cubic microstructure, exhibiting excellent rolling and drawing properties, making it easy to cold-work into desired solder materials. Using a brazing temperature of 1000-1010°C, this solder can smoothly flow-fill welds without the risk of substrate corrosion.

[0058] (2) The chemical composition of medium-temperature solder is: 0.2% silver, 4% copper, 4% zinc, 0.05% indium, 0.01% tin, 0.02% cerium, and the rest is gold and inevitable impurities.

[0059] Testing has shown that the solder exceeds 22K, has a liquidus temperature of 872°C, and a crystallization interval of 46°C. It exhibits excellent fluidity, a wetting angle of 19° with the pure gold substrate, and exhibits no sagging. Within a 0.05mm gap, common in gold filigree, the soldering rate reaches 95% thanks to gravity and capillary forces. The solder has a color value of approximately 88.0 (L*), a chromaticity of 5.2, and a b* of 27.6, compared to the color values ​​of approximately 84.5 (L*), 3.3 (a*), and 21.1 (b*). The color deviation between the solder and pure gold is significantly smaller than with conventional medium-temperature solders. After post-soldering, the color difference between the weld and the substrate is also significantly smaller than with conventional medium-temperature solders. After immersing the solder in artificial sweat at a pH of 6.5 for 8 hours, the color difference of pure gold is approximately 0.25, the color difference of the solder of the present invention is approximately 1.2, and the color difference of traditional gold wire solder is 2.8. Therefore, the solder of the present invention has excellent sweat corrosion resistance, significantly superior to traditional gold wire solder and basically close to that of pure gold. After solution treatment, the solder has a single face-centered cubic microstructure, excellent rolling and drawing properties, and is easy to cold-work into welding materials of the required specifications. The solder of the present invention can smoothly flow-fill the weld at a brazing temperature of 890-900°C, eliminating the risk of high-temperature weld melt collapse.

[0060] (3) The chemical composition of low-temperature solder is: 0.5% silver, 4.5% copper, 9.6% zinc, 0.3% indium, 0.03% tin, 0.01% yttrium, and the rest is gold and unavoidable impurities.

[0061] Testing revealed that the solder exceeded 85% color purity, had a liquidus temperature of 760°C, and a crystallization interval of 44°C. It exhibited excellent fluidity, a wetting angle of 28° with the pure gold substrate, and exhibited no sagging. Within a 0.05mm gap, common in gold filigree, the solder achieved a 95% soldering rate due to gravity and capillary forces. The solder exhibited a color L* value of approximately 85.5, a chromaticity a* value of 5.5, and a b* value of 24.3. This compares favorably to conventional gold filigree low-temperature solder (80% gold, 20% tin), which exhibits color values ​​of approximately L*88.0, a*4.0, and b*16.3, significantly whiter than pure gold. Therefore, the color deviation between the solder and pure gold is significantly smaller than with conventional solders. After post-soldering, the color difference between the weld and the substrate was significantly smaller than with conventional low-temperature solders. After immersion in artificial sweat at a pH of 6.5 for 8 hours, the color difference was approximately 1.8, demonstrating excellent sweat corrosion resistance. After solution treatment, the solder exhibits a single face-centered cubic microstructure, exhibiting excellent rolling and drawing properties, making it easy to cold-work into welding materials of desired specifications. The solder of the present invention can smoothly flow-fill the weld at a brazing temperature of 780-790°C, eliminating the risk of weld melt collapse at intermediate temperatures.

[0062] Example 2

[0063] A gold solder for filigree enamel jewelry, including high-temperature solder, medium-temperature solder, and low-temperature solder. The high-temperature solder is used for the first or initial welding of welded parts, the medium-temperature solder is used for intermediate welding after the welded parts are welded with the high-temperature solder, and the low-temperature solder is used for final assembly welding after the welded parts are welded with the medium-temperature solder.

[0064] Among them, the chemical composition of (1) high temperature grade solder is: 0.87% silver, 3.5% copper, 0.5% zinc, 0.07% indium, 0.02% tin, 0.01% gadolinium, 0.01% lanthanum, and the rest is gold, and inevitable impurities, and inevitable impurities.

[0065] Testing has shown that the solder has a purity exceeding 95%, a liquidus temperature of 986°C, and a crystallization interval of 45°C, demonstrating excellent fluidity. The solder exhibits a single face-centered cubic microstructure, exhibiting excellent rolling and drawing properties, making it easy to cold-work into desired specifications. The solder of the present invention can smoothly flow-fill welds at brazing temperatures of 1000-1010°C without the risk of substrate corrosion.

[0066] (2) The chemical composition of medium-temperature solder is: 0.3% silver, 4.4% copper, 3.5% zinc, 0.05% indium, 0.01% tin, 0.01% neodymium, and the rest is gold and inevitable impurities.

[0067] Testing has shown that the solder has a color exceeding 22K, a liquidus temperature of 881°C, and a crystallization interval of 48°C, demonstrating excellent fluidity. After solution treatment, the solder exhibits a single face-centered cubic microstructure, exhibiting excellent rolling and drawing properties, making it easy to cold-work into desired weld material specifications. The solder of the present invention can smoothly flow-fill welds at brazing temperatures of 900-910°C, eliminating the risk of high-temperature weld melt collapse.

[0068] (3) The chemical composition of low-temperature solder is: 0.1% silver, 4.65% copper, 9.8% zinc, 0.4% indium, 0.01% tin, 0.01% cerium, and the rest is gold and inevitable impurities.

[0069] Testing has shown that the solder has a purity exceeding 85%, a liquidus temperature of 757°C, and a crystallization interval of 46°C, demonstrating excellent fluidity. After solution treatment, the solder exhibits a single face-centered cubic microstructure, exhibiting excellent rolling and drawing properties, making it easy to cold-work into desired specifications. The solder of the present invention can smoothly flow-fill welds at brazing temperatures of 775-785°C, eliminating the risk of melt collapse at intermediate temperatures.

[0070] Example 3

[0071] A gold solder for filigree enamel jewelry, including high-temperature solder, medium-temperature solder, and low-temperature solder. The high-temperature solder is used for the first or initial welding of welded parts, the medium-temperature solder is used for intermediate welding after the welded parts are welded with the high-temperature solder, and the low-temperature solder is used for final assembly welding after the welded parts are welded with the medium-temperature solder.

[0072] Among them, the chemical composition of (1) high temperature grade solder is: 0.3% silver, 3.7% copper, 0.85% zinc, 0.1% indium, 0.01% tin, 0.01% yttrium, and the rest is gold and inevitable impurities.

[0073] Testing has shown that the solder has a purity exceeding 95%, a liquidus temperature of 972°C, and a crystallization interval of 46°C, demonstrating excellent fluidity. The solder exhibits a single face-centered cubic microstructure, exhibiting excellent rolling and drawing properties, making it easy to cold-work into desired specifications. The solder of the present invention can smoothly flow-fill welds at brazing temperatures of 995-1005°C without the risk of substrate corrosion.

[0074] (2) The chemical composition of medium-temperature solder is: 0.1% silver, 3.6% copper, 4.46% zinc, 0.08% indium, 0.03% tin, 0.01% cerium, and the rest is gold and inevitable impurities.

[0075] Testing has shown that the solder has a color exceeding 22K, a liquidus temperature of 860°C, and a crystallization interval of 50°C, demonstrating excellent fluidity. After solution treatment, the solder exhibits a single face-centered cubic microstructure, exhibiting excellent rolling and drawing properties, making it easy to cold-work into desired specifications. The solder of the present invention can smoothly flow-fill the weld at brazing temperatures of 880-890°C, eliminating the risk of high-temperature weld melt collapse.

[0076] (3) The chemical composition of low-temperature solder is: 0.2% silver, 3.5% copper, 11% zinc, 0.2% indium, 0.02% tin, 0.02% lanthanum, and the rest is gold and inevitable impurities.

[0077] Testing has shown that the solder has a purity exceeding 85%, a liquidus temperature of 745°C, and a crystallization interval of 36°C, demonstrating excellent fluidity. After solution treatment, the solder exhibits a single face-centered cubic microstructure, exhibiting excellent rolling and drawing properties, making it easy to cold-work into desired specifications. The solder of the present invention can smoothly flow-fill welds at brazing temperatures of 765-775°C, eliminating the risk of melt collapse at intermediate temperatures.

[0078] Example 4

[0079] A gold solder for filigree enamel jewelry, including high-temperature solder, medium-temperature solder, and low-temperature solder. The high-temperature solder is used for the first or initial welding of welded parts, the medium-temperature solder is used for intermediate welding after the welded parts are welded with the high-temperature solder, and the low-temperature solder is used for final assembly welding after the welded parts are welded with the medium-temperature solder.

[0080] Among them, the chemical composition of (1) high temperature grade solder is: 0.3% silver, 3.7% copper, 0.85% zinc, 0.1% indium, 0.01% tin, 0.01% yttrium, and the rest is gold and inevitable impurities.

[0081] Testing has shown that the solder has a purity exceeding 95%, a liquidus temperature of 972°C, and a crystallization interval of 46°C, demonstrating excellent fluidity. The solder exhibits a single face-centered cubic microstructure, exhibiting excellent rolling and drawing properties, making it easy to cold-work into desired specifications. The solder of the present invention can smoothly flow-fill welds at brazing temperatures of 995-1005°C without the risk of substrate corrosion.

[0082] (2) The chemical composition of medium-temperature solder is: 0.15% silver, 4.2% copper, 3.8% zinc, 0.03% indium, 0.01% tin, 0.01% germanium, 0.01% cerium, and the rest is gold and unavoidable impurities.

[0083] Testing has shown that the solder has a color exceeding 22K, a liquidus temperature of 874°C, and a crystallization interval of 50°C, demonstrating excellent fluidity. After solution treatment, the solder exhibits a single face-centered cubic microstructure, exhibiting excellent rolling and drawing properties, making it easy to cold-work into desired weld material specifications. The solder of the present invention can smoothly flow-fill welds at brazing temperatures of 890-895°C, eliminating the risk of high-temperature weld melt collapse.

[0084] (3) The chemical composition of low-temperature solder is: 0.3% silver, 4.6% copper, 9.8% zinc, 0.2% indium, 0.01% tin, 0.02% germanium, 0.02% lanthanum, and the rest is gold and unavoidable impurities.

[0085] Testing has shown that the solder has a purity exceeding 85%, a liquidus temperature of 758°C, and a crystallization interval of 43°C, demonstrating excellent fluidity. After solution treatment, the solder exhibits a single face-centered cubic microstructure, exhibiting excellent rolling and drawing properties, making it easy to cold-work into desired specifications. The solder of the present invention can smoothly flow-fill welds at brazing temperatures of 780-785°C, eliminating the risk of weld collapse at intermediate temperatures.

[0086] The following is a comparative example (for comparison with the embodiment), which is as follows:

[0087] Comparative Example 1 (Changing the Composition of High-Temperature Grade Solder)

[0088] A gold solder for filigree enamel jewelry, including high-temperature solder, medium-temperature solder, and low-temperature solder. The high-temperature solder is used for the first or initial welding of welded parts, the medium-temperature solder is used for intermediate welding after the welded parts are welded with the high-temperature solder, and the low-temperature solder is used for final assembly welding after the welded parts are welded with the medium-temperature solder.

[0089] Among them, the chemical composition of (1) high temperature grade solder is: 0.01% silver, 0.1% copper, 3% zinc, 1% indium, 0.1% tin, 0.03% germanium, 0.01% yttrium, and the rest is gold and inevitable impurities.

[0090] Testing revealed that the solder had a purity exceeding 95%, a liquidus temperature of 924°C, and a crystallization interval of 118°C. However, the solder exhibited poor fluidity, a wetting angle exceeding 60°, and poor spreading and wetting of fine welds. The soldering rate was less than 70%, significantly inferior to that of the example.

[0091] (2) The chemical composition of medium-temperature solder is: 0.1% silver, 3.6% copper, 4.46% zinc, 0.08% indium, 0.03% tin, 0.01% cerium, and the rest is gold and inevitable impurities.

[0092] (3) The chemical composition of low-temperature solder is: 0.2% silver, 3.5% copper, 11% zinc, 0.2% indium, 0.02% tin, 0.02% lanthanum, and the rest is gold and inevitable impurities.

[0093] Comparative Example 2 (Changing the Composition of Medium-Temperature Grade Solder)

[0094] A gold solder for filigree enamel jewelry, including high-temperature solder, medium-temperature solder, and low-temperature solder. The high-temperature solder is used for the first or initial welding of welded parts, the medium-temperature solder is used for intermediate welding after the welded parts are welded with the high-temperature solder, and the low-temperature solder is used for final assembly welding after the welded parts are welded with the medium-temperature solder.

[0095] Among them, the chemical composition of (1) high temperature grade solder is: 0.3% silver, 3.7% copper, 0.85% zinc, 0.1% indium, 0.01% tin, 0.01% yttrium, and the rest is gold and inevitable impurities.

[0096] (2) The chemical composition of medium-temperature solder is: 1.6% silver, 2% copper, 3% zinc, 1% indium, 0.3% tin, 0.2% germanium, 0.05% cerium, and the rest is gold and inevitable impurities.

[0097] Testing revealed that the solder's color exceeded 22K, its liquidus temperature was 886°C, and its crystallization interval reached 270°C. During heating, the solder remained in a liquid-solid mixed state for a long time, resulting in poor fluidity. Its wetting angle exceeded 74°, making it difficult to spread across the weld. Its soldering rate was less than 70%, significantly contrasting with pure gold. After soaking in artificial sweat, it exhibited a yellowish-gray color and lost its gloss. Therefore, its soldering performance was significantly inferior to that of the example.

[0098] (3) The chemical composition of low-temperature solder is: 0.2% silver, 3.5% copper, 11% zinc, 0.2% indium, 0.02% tin, 0.02% lanthanum, and the rest is gold and inevitable impurities.

[0099] Comparative Example 3 (Changing the Composition of Low-Temperature Grade Solder)

[0100] A gold solder for filigree enamel jewelry, including high-temperature solder, medium-temperature solder, and low-temperature solder. The high-temperature solder is used for the first or initial welding of welded parts, the medium-temperature solder is used for intermediate welding after the welded parts are welded with the high-temperature solder, and the low-temperature solder is used for final assembly welding after the welded parts are welded with the medium-temperature solder.

[0101] Among them, the chemical composition of (1) high temperature grade solder is: 0.3% silver, 3.7% copper, 0.85% zinc, 0.1% indium, 0.01% tin, 0.01% yttrium, and the rest is gold and inevitable impurities.

[0102] (2) The chemical composition of medium-temperature solder is: 0.1% silver, 3.6% copper, 4.46% zinc, 0.08% indium, 0.03% tin, 0.01% cerium, and the rest is gold and inevitable impurities.

[0103] (3) The chemical composition of low-temperature solder is: 0.2% silver, 7.3% copper, 6% zinc, 0.7% indium, 0.5% tin, 0.1% germanium, 0.02% lanthanum, and the rest is gold and unavoidable impurities.

[0104] Testing revealed that the solder's color purity exceeded 85%, its liquidus temperature was 797°C, and its crystallization interval reached 183°C. During heating, the solder remained in a liquid-solid mixed state for a long time, resulting in poor fluidity. Its wetting angle exceeded 65°, making it difficult to spread across the weld. Its soldering rate was less than 73%, significantly contrasting with pure gold. After soaking in artificial sweat, it exhibited a dark yellow color and lost its gloss. Therefore, its soldering performance was significantly inferior to that of the example.

[0105] Comparative Example 4 (Traditional Solder)

[0106] Comparisons were conducted using conventional high-, medium-, and low-temperature solders used in the gold filigree process. The high-temperature solder had a chemical composition of 80% gold, 11% silver, 6% copper, 1.5% zinc, and 1.5% cadmium. The medium-temperature solder had a chemical composition of 60% gold, 22% silver, 10% copper, 4% zinc, 2.5% tin, and 1.5% cadmium. The low-temperature solder had a chemical composition of 80% gold and 20% tin.

[0107] After testing, the performance of traditional welding flux is as follows:

[0108] (1) High-temperature solder has excellent wettability and permeability, with a soldering rate of 88-92% within the weld. Its color is reddish-yellow, a stark contrast to pure gold. After being soaked in sweat, it appears dark yellow or slightly grayish-yellow. The purity of this solder is only 80%, and it contains the toxic element cadmium.

[0109] (2) Medium-temperature solder has good wettability and permeability, with a soldering rate of 84-87% within the weld. Its color is light yellow-red, a stark contrast to pure gold, and it changes color significantly after being soaked in sweat. The purity of this solder is only 60%, and it contains the toxic element cadmium.

[0110] (3) The crystallization interval of low-temperature solder is 97°C, the soldering rate in the weld is less than 80%, the color is obviously light gold, which is in sharp contrast to the color of pure gold, and it darkens after being soaked in sweat. This solder has low welding strength, high brittleness, and the weld is easy to break.

[0111] The above embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and replacements made by technicians in this field on the basis of the present invention fall within the scope of protection required by the present invention.

Claims

1. A gold solder for filigree enamel jewelry, characterized in that: Including high-temperature solder, medium-temperature solder and low-temperature solder. High-temperature solder is used for the first or initial welding of weldments. Medium-temperature solder is used for intermediate welding after weldments are welded with high-temperature solder. Low-temperature solder is used for final assembly welding after weldments are welded with medium-temperature solder. Among them, the high temperature grade solder includes the following components in mass percentage: Silver 0.1-1.5%, copper 0.5-4.0%, zinc 0.2-3.0%, indium 0.01-0.5%, tin 0.01-0.3%, rare earth 0.01-0.1%, the rest is gold, and unavoidable impurity elements; Medium temperature grade solder includes the following components in mass percentage: Silver 0.1-1.5%, copper 3.6-8.0%, zinc 0.5-4.46%, indium 0.03-2.0%, tin 0.01-0.5%, germanium 0-0.5%, rare earth 0.01-0.1%, the rest is gold, and unavoidable impurity elements; Low temperature grade solder includes the following components in mass percentage: Silver 0.1-1.5%, copper 3.0-6.0%, zinc 2.5-11.0%, indium 0.1-1.0%, tin 0.01-1.0%, germanium 0-0.5%, rare earth 0.01-0.1%, the rest is gold, and inevitable impurity elements.

2. The gold solder for filigree enamel jewelry according to claim 1, characterized in that: The total content of the unavoidable impurity elements does not exceed 0.1%.

3. The gold solder for filigree enamel jewelry according to claim 1, characterized in that: The rare earth is one or more of cerium, yttrium, lanthanum, neodymium and gadolinium.

4. The gold solder for filigree enamel jewelry according to claim 1, characterized in that: The color purity of the high-temperature solder is not less than 95%, the color purity of the medium-temperature solder is not less than 91.7%, and the color purity of the low-temperature solder is not less than 85%.

5. The gold solder for filigree enamel jewelry according to claim 1, characterized in that: The highest liquidus temperature of the solder does not exceed 990°C, the lowest solidus temperature is not lower than 700°C, and the welding temperature difference is 60-120°C.

6. The gold solder for filigree enamel jewelry according to claim 5, characterized in that: The liquidus temperature of the high-temperature solder is 960-990°C.

7. The gold solder for filigree enamel jewelry according to claim 5, characterized in that: The liquidus temperature of the medium-temperature solder is 860° C. to 885° C., and the gold content of the medium-temperature solder is not less than 91.7%.

8. The gold solder for filigree enamel jewelry according to claim 5, characterized in that: The liquidus temperature of the low-temperature solder is 730° C. to 760° C., and the gold content of the low-temperature solder is not less than 91.7%.