EP0457350B1 - Edelmetallformkörper, Verfahren zu ihrer Herstellung, formbare Mischung für ihre Herstellung und Verfahren zur Herstellung dieser formbaren Mischung - Google Patents

Edelmetallformkörper, Verfahren zu ihrer Herstellung, formbare Mischung für ihre Herstellung und Verfahren zur Herstellung dieser formbaren Mischung Download PDF

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Publication number
EP0457350B1
EP0457350B1 EP91108050A EP91108050A EP0457350B1 EP 0457350 B1 EP0457350 B1 EP 0457350B1 EP 91108050 A EP91108050 A EP 91108050A EP 91108050 A EP91108050 A EP 91108050A EP 0457350 B1 EP0457350 B1 EP 0457350B1
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EP
European Patent Office
Prior art keywords
precious metal
powder
weight
moldable mixture
moldable
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP91108050A
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English (en)
French (fr)
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EP0457350A1 (de
Inventor
Koji C/O Chuo-Kenkyusho Mitsubishi Hoshino
Masaki C/O Sanda-Kojo Mitsubishi Morikawa
Tohru C/O Chuo-Kenkyusho Mitsubishi Kohno
Koshiro C/O Chuo-Kenkyusho Mitsubishi Ueda
Masaki C/O Chuo-Kenkyusho Mitsubishi Miyakawa
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Mitsubishi Materials Corp
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Mitsubishi Materials Corp
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Publication date
Priority claimed from JP2128447A external-priority patent/JP2760134B2/ja
Priority claimed from JP2178753A external-priority patent/JP2774974B2/ja
Priority claimed from JP2241017A external-priority patent/JP2932648B2/ja
Priority claimed from JP2241018A external-priority patent/JP3004038B2/ja
Priority claimed from JP24101490A external-priority patent/JP2932647B2/ja
Priority claimed from JP2241015A external-priority patent/JPH04120202A/ja
Priority claimed from JP2241016A external-priority patent/JP2924139B2/ja
Priority claimed from JP2270938A external-priority patent/JP2836232B2/ja
Application filed by Mitsubishi Materials Corp filed Critical Mitsubishi Materials Corp
Publication of EP0457350A1 publication Critical patent/EP0457350A1/de
Publication of EP0457350B1 publication Critical patent/EP0457350B1/de
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
    • B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
    • B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
    • A—HUMAN NECESSITIES
    • A44—HABERDASHERY; JEWELLERY
    • A44C—PERSONAL ADORNMENTS, e.g. JEWELLERY; COINS
    • A44C27/00—Making jewellery or other personal adornments
    • A44C27/001—Materials for manufacturing jewellery
    • A44C27/002—Metallic materials
    • A44C27/003—Metallic alloys
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/22—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces for producing castings from a slip
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B44—DECORATIVE ARTS
    • B44C—PRODUCING DECORATIVE EFFECTS; MOSAICS; TARSIA WORK; PAPERHANGING
    • B44C5/00—Processes for producing special ornamental bodies
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy

Definitions

  • the present invention relates to a method for manufacturing a precious metal article for ornaments, artistic handicrafts or the like and further to a moldable mixture specifically adapted to be employed in the manufacture of the precious metal article and a method for producing the moldable mixture itself.
  • Japanese Patent Application laid open with Publication No. 59-143001 describes one conventional method for manufacturing ornamental articles or artistic handicrafts, which involves preparing powders of precious metal such as gold (Au), platinum (Pt) and silver (Ag); adding binders such as clay, glue, boiled rice or wheat flour to them; subsequently mixing them together with water to produce a moldable mixture; modeling an article of a prescribed shape in this moldable mixture; and drying the resulting article at about 100 o C.
  • precious metal such as gold (Au), platinum (Pt) and silver (Ag)
  • binders such as clay, glue, boiled rice or wheat flour
  • Japanese Patent Application laid open with Publication No. 63-403 describes another conventional manufacturing method which includes preparing powder of metal such as nickel (Ni); adding bentonite as binder; mixing them together with water to produce a moldable mixture; modeling an article of a prescribed shape in this mixture; leaving the resulting article at room temperature for a prolonged period of time to remove water; and subsequently sintering it in a reducing atmosphere at 1,250 o C.
  • metal such as nickel (Ni)
  • bentonite as binder
  • modeling an article of a prescribed shape in this mixture leaving the resulting article at room temperature for a prolonged period of time to remove water; and subsequently sintering it in a reducing atmosphere at 1,250 o C.
  • Patent Abstracts of Japan, Vol. 13, No. 13 discloses the production of a composite noble metal alloy product.
  • a powder of light metals coated with nickel, a noble metal powder and a binder are mixed.
  • Such a powder mixture is subjected to injection moldings. Thereafter, the moldings are heated to evaporate the binder. Then the moldings are sintered and afterwards gold-plated.
  • US-A-4,369,068 which discloses all the features of the preamble of claim 12 and describes a preparation consisting essentially of gold powder, an adhesive and a binder of an organic solvent and a resin.
  • the adhesive is a metal powder.
  • As the resin ethyl cellulose may be used.
  • the binder is liquid at room temperature and is volatilized or burned at firing temperature. Said preparation is used for coating metallic particles.
  • Yet another object is to provide a moldable mixture adapted to be used in the above method of manufacturing the precious metal articles.
  • a further object is to provide a method for producing the moldable mixture itself.
  • a method for manufacturing a precious metal article consisting essentially of a solid-phase sintered product of a precious metal powder free of any binder, whereby assuming color tone of the precious metal, comprising preparing a moldable mixture consisting essentially of: 50 to 90 % by weight of a precious metal powder; 0.8 to 8 % by weight of a water-soluble cellulose binder; 0.03 to 3 % by weight of a surface-active agent; 0.1 to 3 % by weight of an adhesion-preventing agent; and balance water and unavoidable impurities, wherein said binder is removable by sintering, shaping the moldable mixture into a prescribed molded object, and subjecting the molded object to solid-phase sintering operation to provide the precious metal article.
  • Various methods can be developed by using the basic idea of this method, and various kinds of precious metal articles of high quality can be successfully produced.
  • a moldable mixture for use in the manufacture of a precious metal article containing a precious metal powder and a binder consisting essentially of 50 to 90 % by weight of a precious metal powder; 0.8 to 8 % by weight of a water-soluble cellulose binder; 0.03 to 3 % by weight of a surface-active agent; 0.1 to 3 % by weight of an adhesion-preventing agent; balance water and unavoidable impurities.
  • the binder employed to prepare the moldable mixture be removable during the manufacture of the precious metal article. It has been found that the cellulose binder is particularly suitable for these purposes. Furthermore, in order to impart other characteristics as necessary, the moldable mixture can be modified in various ways.
  • a method for producing a moldable mixture for use in the manufacture of a precious metal article comprising the steps of preparing a precious metal powder, preparing a jelly-like cellulose binder by blending a cellulose with water and leaving for a prescribed period of time, blending the precious metal powder and the jelly-like cellulose binder together, and adding 0.03 to 3 % by weight of a surface-active agent and 0.1 to 3 % by weight of an adhesion-preventing agent. Said surface-active agent and adhesion-preventing agent are added in order to obtain a better moldable mixture.
  • the inventors have made an extensive study to obtain a precious metal article containing no binder, and have come to know that when a jellylike cellulose, prepared by adding water to cellulose, is used as a binder, water contained therein evaporates during the drying process while the cellulose disappears during the solid-phase sintering process.
  • the resulting metal article is free of binder, and is essentially comprised of a solid-phase sintered product of a precious metal.
  • the inventors have come to understand that if a surface-active agent is added during the mixing of binder and precious metal, a uniform mixing in a short period of time can be positively ensured.
  • an adhesion-preventing agent such as di-n-butyl phthalate
  • the mixture is prevented from sticking to hand during the molding work, and this adhesion-preventing agent as well as the aforesaid surface-active agent can be removed away during the sintering step, so that the color tone of the resulting metal article is not marred.
  • the precious metal article made in accordance with the method of the present invention consists essentially of a solid-phase sintered product of a precious metal powder free of any binder, and assumes the special color tone of the precious metal.
  • the precious metal article is manufactured by the steps of preparing a moldable mixture containing a precious metal, a binder which is removable by sintering, a surface-active agent and an adhesion-preventing agent and subjecting the mixture to solid-phase sintering operation.
  • a moldable mixture containing a precious metal powder and a cellulose binder mixed with the powder is first prepared.
  • the use of the cellulose as the binder ensures that the binder be removed away during the sintering step.
  • the moldable mixture of a precious metal is molded into a prescribed shape, and after being dried, the molded object is sintered under predetermined conditions.
  • the binder is removed during the sintering operation, and a precious metal article free of the binder is manufactured.
  • Figs. 1a to 1d are schematic views showing the steps of the above method in accordance with a first preferred embodiment of the invention.
  • a leaf 1 as shown in Fig. 1a is prepared as a combustible base object. It is preferable that a leaf of tree having a distinct vein be selected.
  • the moldable mixture of the invention is extended thinly by hand on the surface of the leaf 1 and unnecessary portion of the mixture is removed by a bamboo spatula or the like in conformity with the shape of the leaf 1 to provide a molded object 2 having the same shape as the leaf 1.
  • Fig. 1b the moldable mixture of the invention is extended thinly by hand on the surface of the leaf 1 and unnecessary portion of the mixture is removed by a bamboo spatula or the like in conformity with the shape of the leaf 1 to provide a molded object 2 having the same shape as the leaf 1.
  • Fig. 1b the moldable mixture of the invention is extended thinly by hand on the surface of the leaf 1 and unnecessary portion of the mixture is removed by a bamboo spa
  • the molded object 2 is introduced into an electric furnace 3, and subjected to solid-phase sintering operation.
  • the sintering conditions in the electric furnace 3 differ depending upon the kinds of the moldable mixture.
  • the mixture When the mixture is of pure gold, it may be heated in air at 1000 o .
  • the mixture when the mixture is of an alloy of 75.0% by weight of gold, 12.5% by weight of silver and 12.5% by weight of copper, i.e., 18-carat gold, it may be heated in an argon gas atmosphere at 800 o C.
  • the leaf 1 burns to ash, so that it can be easily removed away. With these procedures, a precious metal article 4 having a minute venous pattern reproduced from the surface of the leaf 1 can be obtained as shown in Fig. 1d.
  • the moldable mixture is first extended thinly on the leaf 1 as shown in Fig. 1b, and then another leaf is placed thereon in such a manner that the mixture is sandwiched between the two leaves. Then, the sintering step is carried out under the same conditions as described above.
  • leaves of trees are selected as base objects, but other combustible materials such as paper pattern having a desired design thereon may be employed as well.
  • Figs. 2a to 2d are schematic views showing the steps of the manufacturing method in accordance with a second preferred embodiment of the invention.
  • an object of wax 5 as shown in Fig. 2a is prepared as a base object which is removable by sintering.
  • a moldable mixture of the invention is extended thinly by hand on the outer surface of the object 5 and unnecessary portion of the mixture is removed by a bamboo spatula or the like to provide a molded object 6 of a prescribed shape as shown in Fig. 2b.
  • the molded object 6 is introduced into an electric furnace 7, and is subjected to solid-phase sintering by heating it at 1000 o C in air.
  • the sintering conditions in the electric furnace 3 are the same as those previously mentioned. With the sintering step, the wax quickly evaporates, and hence only the molded object 6 is left as a precious metal article 8.
  • the wax may be replaced by any other material which is vaporizable or liquefiable during the sintering.
  • Figs. 3a and 3b are schematic views showing the steps of the manufacturing method in accordance with a third embodiment of the invention.
  • This embodiment is in particular suitable for manufacturing relatively small-size ornamentations such as pendants.
  • a moldable mixture of the invention is placed on a working table 9 and extended thereon by a roller or the like to produce a plate 10 of the moldable mixture.
  • a prescribed portion 10a is carved and punched into a desired shape using a bamboo spatula or the like to provide a molded object.
  • the molded object thus obtained is introduced into an electric furnace and subjected to solid-phase sintering operation under the same conditions as described above.
  • This method may be further modified so as to be suitably adapted for manufacturing artistic handicrafts of a relatively large size such as picture platters. More specifically, as shown in Fig. 4a, the above procedures are repeated to produce a plate 10 of mixture, and a prescribed portion 10b is removed away using a bamboo spatula. Then, as shown in Fig. 4b, another moldable mixture 10c, which assumes a color tone different from that of the plate 10, is stuffed into the vacant portion 10b of the plate 10 to provide a molded object. Then, the sintering operation is effected in a similar way. In this case, two or more portions may be removed from the plate, and moldable mixtures of different colors may be stuffed thereinto, respectively.
  • Figs. 5a to 5e are schematic views showing the steps of the manufacturing method in accordance with a fourth embodiment of the invention.
  • a plurality of plates of moldable mixtures 11 and 12, which assume different colors after the sintering operation, are prepared and formed flat by a roller.
  • the mixtures 11 and 12 are placed one upon another with alternations of different colors.
  • the plates of mixtures are vertically cut in pieces each having a stripe pattern, and as shown in Fig. 5d, these stripe pieces are piled one upon another in such a manner that the mixtures of different colors are displaced adjacent to each other.
  • the piled mixtures are sliced in a prescribed direction to produce sliced plates each having a checker pattern as shown in Fig. 5e.
  • Sliced plates thus obtained are sintered in an electric furnace or the like under the same conditions as described above, so that precious metal articles having checker patterns can be obtained.
  • the method shown in 6a to 6c is another modification, wherein a moldable mixture 13 is shaped into a rectangular parallelepiped, and a plurality of apertures of a prescribed cross-sectional shape are formed therethrough. Then, another moldable mixture 14 of different color is stuffed into each of the apertures. In this case, moldable mixtures 14 of different colors may be stuffed.
  • the rectangular parallelepiped thus formed is cut into slices each having a pattern in which plural isolated portions of different color are scattered. These sliced plates are then sintered under the same conditions as described above.
  • This method may be further modified as shown in Figs. 7a to 7c.
  • two plates 15 and 16 of different moldable mixtures are placed one upon another, and are wound round as depicted in Fig. 7b.
  • the cylindrical mixtures thus formed are then sliced into circular disks each having a vortex pattern. These disks are finally sintered in a furnace to provide precious metal articles having vortex patterns.
  • two or more moldable mixtures may be blended together before the molding operation.
  • precious metal articles having complicated patterns can be obtained.
  • the article obtained by the sintering operation may be further subjected to plastic working to thereby modify the shape of the article.
  • Figs. 8a to 8d are schematic views showing the steps of the manufacturing method in accordance with a fifth embodiment of the invention.
  • This embodiment is also suitable for manufacturing relatively small-size ornamentations such as pendants.
  • a prescribed moldable mixture is placed on a working table and extended thereon by a roller or the like, and shaped by handwork with a bamboo spatula or the like or punching operation into a heart-shaped molded object 17 as shown in Fig. 8b.
  • powdered glass 18 is caused to adhere to its surface at a prescribed portion thereof, and is sintered in a furnace 19 under the same conditions as described above.
  • a glassy layer 20 is formed on a desired portion on the surface, and a precious metal article 21 having a glassy portion 20 on its surface can be obtained.
  • This article 21 is, for example, secured to a necklace 22.
  • a coloring agent is mixed into the powdered glass, a glassy layer of a desired color can be obtained.
  • the shape of the article is of course arbitrary.
  • a suitable jewel may be directly attached to the moldable mixture before the sintering operation. With this procedure, the jewel attached to the mixture remain in the resulting article as it is, so that a precious metal article having a jewel secured thereto in advance can be obtained.
  • the moldable mixture in accordance with the invention is characterized in that it contains a precious metal powder and a cellulose binder mixed with the powder.
  • the use of the cellulose as the binder ensures that the binder is removed away during the sintering step.
  • a water-soluble cellulose is prepared and blended with water, and is left for a predetermined period of time to thereby produce a jellylike cellulose binder. It is preferable that cellulose and water are blended at a ratio of cellulose to water ranging from 5/95 to 30/70. Then, the resulting binder and a prescribed precious metal powder are blended preferably in an amount of 7 to 33 % by weight with respect to the total amount of the mixture.
  • the mixture is such that it contains the surface-active agent and the adhesion-preventing agent, and consists essentially of 50 to 90% by weight of the precious metal powder, 0.8 to 8% by weight of the water-soluble cellulose binder, 0.03 to 3% by weight of the surface-active agent and 0.1 to 3% by weight of the adhesion-preventing agent, balance water and unavoidable impurities.
  • a surface-active agent such as alkyl benzene sodium sulfonate or polysoap
  • an adhesion-preventing agent such as oil
  • the mixture is such that it contains the surface-active agent and the adhesion-preventing agent, and consists essentially of 50 to 90% by weight of the precious metal powder, 0.8 to 8% by weight of the water-soluble cellulose binder, 0.03 to 3% by weight of the surface-active agent and 0.1 to 3% by weight of the adhesion-preventing agent, balance water and unavoidable impurities.
  • This moldable mixture is prepared by blending cellulose binders with water to leave them for a while until jelly substance is formed, adding the active-surface agent to the jelly substances and mixing them together, mixing the precious metal powder therewith, and further adding the adhesion-preventing agent to produce the moldable mixture.
  • Powders of precious metal such as gold, silver, copper, platinum and their alloys are main constituents for the moldable material to be obtained. If the content is less than 50% by weight, desired effects cannot be obtained. On the other hand, if the content exceeds 90% by weight, the resulting moldable material is inferior in extensibility and strength. Therefore, the content of the precious metal powder has been determined so as to range from 50 to 90% by weight.
  • the average particle size of the precious metal powder exceeds 200 ⁇ m, the extensibility and strength are deteriorated. Therefore, it is preferable that the average particle size of the precious metal powder is no greater than 200 ⁇ m.
  • the water soluble binder When heated, the water soluble binder is quickly gelled, so that it is very easy to keep the shape of the molded article.
  • the binder content is less than 0.8% by weight, such an advantage cannot be obtained.
  • the content exceeds 8% by weight, fluidity is unduly increased, so that it becomes difficult to mold the mixture. Therefore, the content of the cellulose binder is determined so as to range from 0.8 to 8% by weight.
  • methyl cellulose and/or ethyl cellulose are favorably used as the water-soluble binder of the above kind.
  • a surface-active agent breaks solid substances which are formed by the reaction of the binder with water, and facilitates an efficient mixing of the precious metal powder with the binder. However, if its content is less than 0.03% by weight, desired effects cannot be obtained. On the other hand, if the content exceeds 3% by weight, the fluidity of the moldable mixture is unduly reduced, so that molding operation cannot be smoothly carried out. Accordingly, the content of the surface-active agent to be added is determined so as to range from 0.03 to 3% by weight. As described above, polysoap or alkyl benzene sodium sulfonate is preferable as this agent.
  • the content of the adhesion-preventing agent is determined so as to range from 0.1 to 3% by weight.
  • This agent may include higher organic acid such as phthalic acid, higher organic ester such as di-n-octyl phthalate or di-n-butyl phthalate, higher alcohol, higher polyhydric alcohol such as polyvinyl alcohol, polyethylene glycol, and higher ether.
  • organic acid such as phthalic acid
  • organic ester such as di-n-octyl phthalate or di-n-butyl phthalate
  • alcohol higher polyhydric alcohol such as polyvinyl alcohol, polyethylene glycol, and higher ether.
  • the precious metal powder to be used in the invention may contain various kinds of precious metal powders. As described above, the moldable mixtures of different colors may be used in the invention. In this case, the color can be controlled by the blending composition of the powder. More specifically, in order to emphasize whitish color, a precious metal powder containing an increased amount of palladium (Pd), nickel, silver or the like is preferably used, while the reddish color tone can be achieved by increasing the copper content.
  • the precious metal powder to be used in the invention gold powder is mainly utilized, but powder of an alloy of various precious metals is also contained in order to control the moldability of the mixture and the strength and color tone of the resulting precious metal article. Since it is impossible to produce the alloy powder by submerged-reduction method, the alloy powder as well as the gold powder are conventionally manufactured by a gas atomizing process. However, when manufactured by the gas-atomizing process, the average particle sizes of the obtained powders are varied widely, so that a moldable mixture having excellent and stable quality cannot be obtained.
  • gold powder is manufactured by means of submerged reduction method, and the alloy powder is manufactured by gas-atomizing method. More specifically, 5 l of aqueous AuCl3 solution having a concentration of 46 g/l and 5 l of aqueous K2SO3 solution having a concentration of 70 g/l are quickly blended at a temperature of -10 o C to +5 o C, preferably at 2 o C. With this procedure, the following reaction takes place, and particles of gold powder precipitates in 5 to 10 seconds. 2AuCl3 + 3K2SO3 + 3H2O ⁇ 2Au + 3K2SO4 + 6HCl Then, these precipitates are filtered to produce gold powder.
  • the gold thus obtained has a particle size of about 10 to 100 ⁇ m, and each individual particle of the powder has protuberances of about 0.1 to 1 ⁇ m adherent thereto.
  • the rate of reaction is reduced.
  • the temperature exceeds 5 o C, the obtained particles become small in size, so that the particles flocculate.
  • the alloy powders which are to be blended with the above gold powder are manufactured by means of gas-atomizing method. Namely, alloy powder containing silver or copper, alloy powder containing nickel or palladium, or alloy powder containing zinc (Zn), cobalt (Co), beryllium (Be), tin (Sn) or indium (In) is manufactured. With respect to the powder containing silver or copper, the hardness, strength, color tone and the like of the moldable mixture can be changed by controlling the content. Also, nickel or palladium is suitable to emphasize white. Zinc is effective to regulate the color tone. Cobalt, beryllium, tin or indium enhances the strength of the moldable mixture. These powders may be manufactured in the state of alloy, but may be produced by blending the individual precious metal powders which have been independently produced.
  • Fig. 9 is a view schematically showing the particles of gold and alloy thus obtained, in which the gold powder and the alloy powder are designated by the numerals 23 and 24, respectively.
  • Methyl cellulose selected as water-soluble cellulose binder, was mixed with water and left over night to produce gelatinous substances.
  • a surface-active agent was added to the gelatinous substances and mixed in a mortar, and then powder of gold having an average particle size of 20 ⁇ m was added thereto. After mixed in the mortar again, di-n-buthyl phthalate was added to the mixture and mixed in the mortar.
  • moldable mixtures 1 to 22 of the invention and comparative moldable mixtures 1 to 8 each having the composition as set forth in Tables 1-1 and 1-2 were manufactured.
  • prior art moldable mixture 1 containing gold powder which is used in a conventional doctor blade method was prepared, and prior art moldable mixture 2 was also produced by adding bentonite power and water to the above gold powder.
  • the pressed compacts were introduced into an electric furnace without drying them, and were heated at a heating speed of 20 o C/min and sintered by holding them in air atmosphere at 1050 o C for one hour. Then the existence of cracks on the surface of the sintered products were observed, and the results are also set forth in Tables 1-1 and 1-2.
  • the prior art moldable mixture 1 cannot be molded due to unduly high fluidity, while the prior art moldable mixture 2 much adhered to the upper and lower molds and cracks were developed in the sintered product.
  • the amount adhering to the upper and lower molds are extremely small, and no cracking was observed even when the pressed compacts were sintered in an electric furnace without drying.
  • Various jelly binders were prepared by blending cellulose so as to have compositions set forth in Table 2, and polysoap was blended as accelerator for mixing. Then, precious metal powders having an average particle size of no greater than 15 ⁇ m were blended to produce moldable mixtures, and further di-n-butyl phthalate was mixed as an adhesion-preventing agent in an amount as set forth in Table 2. Using the moldable mixtures thus prepared, annular molded articles having an outer diameter of 17 mm, an inner diameter of 15 mm and a thickness of 1 mm were molded. Thereafter, the molded articles were subjected drying and sintering under the conditions as set forth in Table 1 to provide precious metal articles 1 to 12 of the invention.
  • the precious metal articles 1 to 12 of the invention contain substantially no binders, surface-active agents and/or adhesion-preventing agents.

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  • General Chemical & Material Sciences (AREA)
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Claims (25)

  1. Verfahren zur Herstellung eines Edelmetallartikels, bestehend im wesentlichen aus einem Festphasengesinterten Produkt eines Edelmetallpulvers, frei von jeglichem Binder, wobei der Artikel den Farbton des Edelmetalls annimmt, umfassend die Herstellung einer formbaren Mischung, bestehend im wesentlichen aus:
    50 bis 90 Gew.% eines Edelmetallpulvers;
    0,8 bis 8 Gew.% eines wasserlöslichen Zellulosebinders;
    0,03 bis 3 Gew.% eines oberflächenaktiven Mittels;
    0,1 bis 3 Gew-% eines Antihaftmittels;
    Rest Wasser und unvermeidbare Verunreinigungen;
    worin der Binder durch Sintern entfernbar ist, Formen der formbaren Mischung zu einem bestimmten geformten Objekt und Unterwerfen des geformten Objekts einer Festphasensinterbehandlung unter Bereitstellung des Edelmetallartikels.
  2. Verfahren zur Herstellung eines Edelmetallartikels nach Anspruch 1, das ferner die Herstellung eines Basisobjektes, das durch Sintern entfernbar ist, umfaßt;
    wobei der Formschritt das Ausbreiten der formbaren Mischung auf dem Basisobjekt umfaßt, der Sinterschritt das Sintern des geformten Objekts und des Basisobjekts umfaßt, wodurch das Basisobjekt während des Sinterns entfernt wird.
  3. Verfahren zur Herstellung eines Edelmetallartikels nach Anspruch 2, worin das Basisobjekt aus einem während des Sinterns verbrennbaren Materials aufgebaut ist.
  4. Verfahren zur Herstellung eines Edelmetallartikels nach Anspruch 2, worin das Basisobjekt aus einem während des Sinterns verflüssigbaren Materials gebildet ist.
  5. Verfahren zur Herstellung eines Edelmetallartikels nach Anspruch 2, worin das Basisobjekt aus einem während des Sinterns vaporisierbaren Materials gebildet ist.
  6. Verfahren zur Herstellung eines Edelmetallartikels nach einem der Ansprüche 1 bis 5, worin ein Formschritt das Formen der formbaren Mischung in eine Platte und Ausstechen eines bestimmten Teils der Platte unter Bereitstellung des geformten objekts mit einer bestimmten Form umfaßt.
  7. Verfahren zur Herstellung eines Edelmetallartikels nach einem der Ansprüche 1 bis 6, das ferner die Herstellung von mindestens zwei formbaren Mischungen umfaßt, wobei der Formungsschritt das Formen einer der formbaren Mischung in eine Platte und Entfernen eines bestimmten Teils der Platte unter Bildung eines freien Bereichs umfaßt, und Einfügen der anderen formbaren Mischung in die freie Region der Platte unter Bereitstellung des geformten Objekts.
  8. Verfahren zur Herstellung eines Edelmetallartikels nach einem der Ansprüche 1 bis 7, was ferner die Herstellung von mindestens zwei Arten von formbaren Mischungen umfaßt, die verschiedene Farben annehmen, durch eine Sinterbehandlung, Vermischen der formbaren Mischung unter Bereitstellung des gemischten formbaren Materials und Formen der geformten Objekte unter Verwendung des vermischten formbaren Materials.
  9. Verfahren zur Herstellung eines Edelmetallartikels nach Anspruch 8, das ferner das Unterwerfen eines gesinterten Produkts, das im Sinterschritt erhalten wird, einer plastischen Bearbeitung umfaßt.
  10. Verfahren zur Herstellung eines Edelmetallartikels nach einem der Ansprüche 1 bis 9, das ferner das Anhaften von Glasmaterial auf dem geformten Objekt an einer bestimmten Oberfläche umfaßt, wobei das Glasmaterial schmilzt und sich über das Objekt ausbreitet, wenn der Sinterschritt durchgeführt wird.
  11. Verfahren zur Herstellung eines Edelmetallartikels nach einem der Ansprüche 1 bis 10, das ferner das Aufbringen eines Edelsteins aus dem geformten Objekt umfaßt, wobei nach Abschluß der Sinteroperation der Edelstein auf dem Edelmetallartikel verbleibt.
  12. Formbare Mischung zur Verwendung im Herstellungsverfahren gemäß einem der Ansprüche 1 bis 11, umfassend ein Edelmetallpulver und einen Binder, dadurch gekennzeichnet, daß er besteht aus
    50 bis 90 Gew.% eines Edelmetallpulvers;
    0,8 bis 8 Gew.% eines wasserlöslichen Zellulosebinders;
    0,03 bis 3 Gew.% eines oberflächenaktiven Mittels;
    0,1 bis 3 Gew.% eines Antihaftmittels;
    Rest Wasser und unvermeidbare Verunreinigungen.
  13. Formbare Mischung nach Anspruch 12, die ferner Ethylenglycol in einer Menge von nicht größer als 30 Gew.%, bezogen auf Wasser, enthält.
  14. Formbare Mischung nach Anspruch 12 oder 13, worin das Edelmetallpulver eine mittlere Partikelgröße von nicht größer als 200 µm hat.
  15. Formbare Mischung nach einem der Ansprüche 12 bis 14, worin das Edelmetallpulver Goldpulver und Pulver einer Legierung, die ein Metall ausgewählt aus Silber und Kupfer enthält, umfaßt.
  16. Formbare Mischung nach einem der Ansprüche 12 bis 15, worin das Goldpulver erhalten wird durch Untertauch-Reduktionsverfahren, wogegen das Legierungspulver durch ein Gas-Atomisierungsverfahren erhalten wird.
  17. Formbare Mischung nach Anspruch 16, worin das Edelmetallpulver ferner ein Gas-atomisiertes Pulver einer Legierung eines Metalls enthält, ausgewählt aus Nickel, Palladium, Zink, Kobalt, Beryllium, Zinn und Indium.
  18. Formbare Mischung nach Anspruch 15, worin das Edelmetallpulver Goldpulver enthält, wobei an jedem einzelnen Teilchen kleinere Protuberanzen anhaften.
  19. Formbare Mischung nach Anspruch 18, worin das Goldpulver eine mittlere Partikelgröße von ca. 10 µm hat.
  20. Formbare Mischung nach einem der Ansprüche 12 bis 19, worin der Binder ausgewählt ist aus Methylzellulose und Ethylzellulose, wobei das oberflächenaktive Mittel ausgewählt ist aus Polyseife und Alkylbenzolnatriumsulfonat, das Antihaftmittel ausgewählt ist aus einer höheren organischen Säure, einem höheren organischen Ester, einem höheren Alkohol, einem höheren polybasischen Alkohol und höheren Ethern.
  21. Verfahren zur Herstellung einer formbaren Mischung nach einem der Ansprüche 12 bis 20 umfassend die Schritte:
    Herstellung ein von 50 bis 90 Gew.% eines Edelmetallpulvers;
    Herstellung von 0,8 bis 8 Gew.% eines Gel-artigen Zellulosebinders durch Vermischen einer Zellulose mit Wasser und Stehenlassen für einen bestimmten Zeitraum;
    Vermischen des Edelmetallpulvers des Gel-artigen Zellulosebinders miteinander; und
    Zugeben von 0,03 bis 3 Gew.% eines oberflächenaktiven Mittels und 0,1 bis 3 Gew.% eines Antihaftmittels.
  22. Verfahren nach Anspruch 21, worin die Zellulose und das Wasser mit einem Verhältnis von Zellulose zu Wasser von 5/95 bis 30/70 vermischt werden, und der gebildete Binder in einer Menge von 7 bis 33 Gew.%, bezogen auf die Gesamtmenge der formbaren Mischung vermischt wird.
  23. Verfahren nach Anspruch 22, das ferner die Zugabe von Ethylenglycol in einer Menge von nicht größer als 30 Gew.% bezüglich Wasser umfaßt.
  24. Verfahren nach Anspruch 21, das ferner die Herstellung von Goldpulver durch Eintauch-Reduktionsverfahren und ein Legierungspulver durch ein Gas-Atomisierungsverfahren, und das Mischen des Goldpulvers und des so hergestellten Legierungspulvers unter Bereitstellung des Edelmetallpulvers umfaßt.
  25. Verfahren nach Anspruch 24, das ferner die Aufnahme eines gasatomisierten Legierungspulvers eines Metalls, ausgewählt aus Nickel, Palladium, Zink, Kobalt, Beryllium, Zinn und Indium, umfaßt.
EP91108050A 1990-05-18 1991-05-17 Edelmetallformkörper, Verfahren zu ihrer Herstellung, formbare Mischung für ihre Herstellung und Verfahren zur Herstellung dieser formbaren Mischung Expired - Lifetime EP0457350B1 (de)

Applications Claiming Priority (18)

Application Number Priority Date Filing Date Title
JP128447/90 1990-05-18
JP2128447A JP2760134B2 (ja) 1990-05-18 1990-05-18 貴金属造形用可塑性組成物
JP178753/90 1990-07-06
JP2178753A JP2774974B2 (ja) 1990-07-06 1990-07-06 貴金属焼結体製装飾品および美術工芸品の製造方法
JP241015/90 1990-09-11
JP2241018A JP3004038B2 (ja) 1990-09-11 1990-09-11 金属物品の製造方法
JP24101490A JP2932647B2 (ja) 1990-09-11 1990-09-11 金属物品の製造方法
JP241016/90 1990-09-11
JP2241015A JPH04120202A (ja) 1990-09-11 1990-09-11 金属物品の製造方法
JP2241017A JP2932648B2 (ja) 1990-09-11 1990-09-11 金属物品の製造方法
JP2241016A JP2924139B2 (ja) 1990-09-11 1990-09-11 金属物品の製造方法
JP241014/90 1990-09-11
JP241017/90 1990-09-11
JP241018/90 1990-09-11
JP2270938A JP2836232B2 (ja) 1990-10-09 1990-10-09 合金金粘土
JP270938/90 1990-10-09
JP27093990 1990-10-09
JP270939/90 1990-10-09

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EP0457350A1 EP0457350A1 (de) 1991-11-21
EP0457350B1 true EP0457350B1 (de) 1995-10-18

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US5328775A (en) * 1990-05-18 1994-07-12 Mitsubishi Materials Corporation Moldable mixture for use in the manufacturing of precious metal articles
JP3896181B2 (ja) * 1997-01-30 2007-03-22 相田化学工業株式会社 貴金属製品の製造方法
DE19854965A1 (de) * 1998-12-02 2000-06-21 Christine Leins Schmuckkörper, aus Teilkörpern zusammengesetzt, und Verfahren zu ihrer Herstellung
JP2001059103A (ja) * 1999-08-19 2001-03-06 Injex Corp 金属焼結体の製造方法
EP1442811B1 (de) 2001-09-28 2012-03-14 Mitsubishi Materials Corporation Silberton mit silberpulver
EP1819467A4 (de) * 2004-10-14 2010-01-20 Tokusen U S A Inc Verfahren zur herstellung hochreiner silberteilchen
EP2074064A4 (de) 2006-09-21 2013-06-05 Tokusen U S A Inc Tieftemperaturverfahren zur herstellung von nanoskaligen titandioxidteilchen
DE102009017596B3 (de) * 2009-04-16 2010-11-11 Ami Doduco Gmbh Verfahren zur Herstellung eines Halbzeugs für Mokume Gane Schmuck
CH701507A1 (fr) * 2009-07-31 2011-01-31 Roth & Genta Haute Horlogerie Procédé d'assemblage de pièces en alliage d'or.
ITMI20120331A1 (it) 2012-03-02 2013-09-03 Legor Group S P A Silver-based alloy powder for manufacturing of 3-dimensional metal objects
JP6241227B2 (ja) * 2013-11-28 2017-12-06 三菱マテリアル株式会社 貴金属焼結体用粘土状組成物
JP6241228B2 (ja) * 2013-11-28 2017-12-06 三菱マテリアル株式会社 貴金属焼結体形成用粘土状成形体
KR101386234B1 (ko) * 2013-12-30 2014-04-17 이남득 동 메탈스톤과 그 제조방법 및 이를 이용한 악세사리
FR3160602A1 (fr) * 2024-03-27 2025-10-03 Van Cleef & Arpels SA Procédé de fabrication d’un bloc composite utilisé pour la fabrication d’un article de joaillerie ou d’horlogerie

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US3052532A (en) * 1961-02-14 1962-09-04 Stephen D Stoddard Casting slips for fabrication of refractory metal ware
FR2158116A1 (en) * 1971-11-03 1973-06-15 Du Pont Gold powder prodn - for printed circuits
JPS6036354B2 (ja) * 1979-07-02 1985-08-20 三菱マテリアル株式会社 装飾部品用金属複合材の製造法
US4249955A (en) * 1980-01-07 1981-02-10 Kennametal Inc. Flowable composition adapted for sintering and method of making
US4369068A (en) * 1981-08-10 1983-01-18 Degussa Aktiengesellschaft Gold containing preparation for coating metallic parts
GB8409046D0 (en) * 1984-04-07 1984-05-16 Mixalloy Ltd Production of flat products in strip &c form
DE3841903A1 (de) * 1988-12-13 1990-06-21 Degussa Verfahren zur herstellung einer dekoration aus edelmetall

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CA2042845C (en) 1999-10-05
KR0179371B1 (ko) 1999-02-18
CA2042845A1 (en) 1991-11-19
EP0457350A1 (de) 1991-11-21
AU638832B2 (en) 1993-07-08
DE69113859D1 (de) 1995-11-23
ATE129130T1 (de) 1995-11-15
AU7709791A (en) 1991-11-21

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