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WO2009092920A2 - Piece of jewellery or timepiece made of solid gold alloy having a white colour, the entirety of which is shining - Google Patents

Piece of jewellery or timepiece made of solid gold alloy having a white colour, the entirety of which is shining Download PDF

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Publication number
WO2009092920A2
WO2009092920A2 PCT/FR2008/001570 FR2008001570W WO2009092920A2 WO 2009092920 A2 WO2009092920 A2 WO 2009092920A2 FR 2008001570 W FR2008001570 W FR 2008001570W WO 2009092920 A2 WO2009092920 A2 WO 2009092920A2
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WO
WIPO (PCT)
Prior art keywords
gold
alloy
niobium
part according
piece
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PCT/FR2008/001570
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French (fr)
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WO2009092920A3 (en
Inventor
Gérard Bienvenu
François Lacoste
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X-Or
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Publication of WO2009092920A2 publication Critical patent/WO2009092920A2/en
Publication of WO2009092920A3 publication Critical patent/WO2009092920A3/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C5/00—Alloys based on noble metals
    • C22C5/02—Alloys based on gold
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/02—Making non-ferrous alloys by melting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/14—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of noble metals or alloys based thereon
    • 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

Definitions

  • the invention relates to a piece of jewelery, timepieces or jewelery comprising a solid gold alloy, white color, titrating at least 14 carats and its production process.
  • the gold-based alloys have been the subject of much research to give them special properties and in particular to give them a particular color, hardness, machinability and improved biocompatibility.
  • Metallurgists have also sought to increase the hardness of gold, without altering its color, by additions of metals selected from Al, Mg, Cu, Ag, Zn, Ru, Co, Si, Mn, Fe, Ni, Pd. , In, Sn, Sb, Pb, Bi, etc.
  • Alloys called "white” alloys, based on indium, gallium, tin are often used to make solders or special materials for optoelectronics, but they are brittle.
  • the object of the invention is a piece of jewelery, timepieces or jewelery made of solid golden gold alloy, of white color, radiant in all its mass and not tarnishable.
  • the gold-based part is more particularly machinable, non-brittle, with a hardness greater than 200HV and biocompatible.
  • the piece comprises gold combined with at least one refractory metal selected from the refractory metals of columns IVB 1 VB and VIB of the periodic table.
  • the refractory metal is selected from chromium, niobium, vanadium, tantalum, zirconium and hafnium.
  • the alloy comprises at least one additional metal selected from tin, indium, galium and germanium.
  • Another object of the invention is to provide a method of making such a part simple and easy to implement.
  • this object is attained by the fact that a charge comprising at least gold and the refractory metal, is arranged in a roughly divided form, in a refractory crucible, before being placed in an oven, under Neutral atmosphere, to be melted, the resulting molten alloy is then quickly poured into a chilled copper mold, having the shape of the piece.
  • the oven may be a tilting induction furnace, the load having been previously compacted to promote induction.
  • timepieces and jewelery comprising a gold-based alloy, solid and grading at least 50% by weight of gold (in particular 14 carats) and preferably at 75% of gold (18 carats), gold is combined with one or more refractory metals selected from:
  • the alloy can thus advantageously be a binary gold / niobium alloy comprising at least 62% of gold (ie at least 14 carats) or a binary gold / chromium alloy containing at least 18% of chromium.
  • the alloy may also comprise an additional metal selected from tin, indium, gallium and germanium.
  • the alloy may comprise a refractory metal selected from niobium, chromium and vanadium and an additional metal selected from tin and indium.
  • Such alloys comprising highly refractory metals have the particularity of giving the piece of jewelery or watchmaking a particular aesthetic appearance, ie a white color, radiant over their entire mass, without the need for subsequent surface treatment. , while having very interesting mechanical properties, particularly as regards the machining possibilities. These parts having such properties mechanical and aesthetic are, in particular, used in the field of jewelery, jewelery and watchmaking.
  • the refractory metals capable of being alloyed with gold, niobium, chromium, vanadium and titanium are advantageously chosen because the Au-Nb, Au-V and Au-Ti binary systems can form alloys having transformations. allotropic in the solid state.
  • the Au-Nb binary system at 25% Nb by weight forms, between 920 ° C. and 1420 ° C., a homogeneous solid solution.
  • 920 ° C. it is the composition of a eutectoid, which is converted into two fine precipitates of compounds defined in Au 2 Nb and Au 2 Nb 3 .
  • This alloy can therefore by a simple heat treatment, (annealing at 1000 ° C. and quenching), be converted back into a continuous solid solution.
  • Example 1 illustrates the demonstration of the diffusion of niobium in gold. It has, in fact, been found, surprisingly, that by accidentally contacting molten gold with niobium (a drop of gold deposited on a niobium disk at 1500 ° C.), the two metals reacted to form locally a white alloy having a very good appearance and having a high mechanical strength.
  • Example 2 illustrates the development of an 18-carat gold-binary alloy.
  • a filler comprising 400 g of shot gold and 127 g of coarsely divided niobium powder was placed in an alumina crucible, in the same oven and under the same conditions as in Example 1. The molten alloy was then quickly poured into a chilled copper mold, having the shape of the piece.
  • a color is, in fact, identified by three values:
  • L 1 the luminance, expressed as a percentage (0 for black to 100 for white) has and b two color ranges from green to red and blue to yellow respectively, with values ranging from -120 to +120.
  • the Lab mode thus covers the entire spectrum visible to the human eye and represents it in a uniform manner. It allows to describe all visible colors.
  • the hardness of the alloy is 337 Hv0.3 and it was found that this alloy could be machined by conventional tools: lathe, cutter equipped with carbide tools.
  • alloys based on gold of a beautiful white color and having very interesting mechanical properties can be formed with highly refractory metals such as V, Ta, Ti, Zr and Hf and preferably Cr.
  • the Au-Cr binary alloy gives, by cooling, two phases, ⁇ 'and Cr, whose amount of ⁇ ' represents 55 atomic% of the total.
  • the liquid alloy is quenched to 1432 ° C, two phases are obtained:>> solid solution rich gold to 18% of chromium (atomic) "- A solid solution rich in chromium to 9% gold (in atoms), this last solid solution being minority (18% of the total).
  • the alloy may also be a binary alloy composed of at least 58.35% gold (14 karat) and chromium.
  • the Au-V binary alloy at 75% gold melts at 1430 ° C, it solidifies forming two phases, a homogeneous solid solution having the structure of gold and a defined V 3 Au compound representing 21% fraction molar.
  • the alloy may also have two refractory metals, which varies the physical properties, but allows to maintain the whiteness which is variable in the color model La * b * (also known as CIELab), preferably between ⁇ 3, b ⁇ 8) and preferably (a ⁇ 1, b ⁇ 3).
  • La * b * also known as CIELab
  • the alloy may also be constituted by a ternary alloy, comprising, for example, gold, niobium and chromium. It may include at least
  • Atomic number of chromium and the atomic percentage of niobium may be equal to 1 (Nb / Cr eutectic), and to 2 (defined compound Cr 2 Nb), but all the proportions are interesting and in particular the value 7.33 which corresponds to 1 Cr / Nb eutectic rich in chromium.
  • the brightness of the alloys can be controlled and / or modified, by the addition of one or more additional metals, highly fusible and very "white", such as gallium, indium, tin and germanium and advantageously tin and indium and even more particularly tin, which has more affinities than In for chromium, niobium and vanadium.
  • Example 3 illustrates the production of an 18-carat gold-niobium-indium ternary alloy.
  • Alloy according to Example 2 heat-treated by annealing performed at 1200 ° C. and 800 ° C. followed by tempering to vary the proportion of homogeneous solid solution. The influence of these treatments is appreciated by the diffractograms made and hardness measurements.
  • the solid solution has a hardness Hv between 250 and 337, while the 2-phase domain Au2Nb and Au2Nb3 has a hardness greater than 600Hv.
  • the alloy consists mainly of a solid solution of gold, the peaks on the diffractogram are slightly offset from those of pure gold.
  • new phases are formed, including Au2Nb and Au2Nb3, the gold solid solution is still present.
  • the annealing time has been increased. Heat treatment at 1200 ° C. for 2 hours followed by annealing at 800 ° C. for 12 hours was carried out.
  • the alloy may also be a quaternary gold / niobium / tin / indium compound compound, for example, in mass proportions of 75% gold, 7% niobium, 9.1% indium and 8.9% by weight. % tin.
  • the proportions of tin and indium in this quaternary alloy correspond to the eutectic composition of the Sn-In binary.
  • alloys having a white appearance varying between the color of gold-based alloys and palladium and that of jewelery alloys based on gold and indium at 75% gold are possible.
  • a ternary alloy gold / nobium / indium composed of 75% gold, 18% indium and 7% niobium has a color equivalent to that of rhodium palladium gold.
  • a gold / niobium / tin ternary alloy composed of 75% gold, 18% tin and 7% niobium has a lighter white color than platinum used in jewelery.
  • the color of 316L stainless steel is, for example, between that of platinum jewelery and that of gold-palladium rhodium.
  • the jeweler or watchmaking pieces comprising these gold-based alloys according to the invention have the advantage of being solid, of a white color throughout their mass, with advantageously a hardness, a biocompatibility, a machinability and a sparkle. improved metal.
  • the white is shiny and brilliant on all the mass of the alloy and not only on the surface.
  • such alloys do not involve any additive element, likely to cause tarnishing of the workpiece, that is to say oxidizable metals, such as iron or manganese or metals that can tarnish as well. 'money.
  • gold-based alloys having very interesting colorimetric characteristics in bright white and in all their mass, hardnesses between 200 and 500Hv, melting preferably between 1100 and 1500 0 C may be proposed.
  • all these alloys are biocompatible and can be machined mechanically to achieve various forms and varied.
  • the silicon carbide resistor furnace mentioned in Examples 1 to 4 could advantageously be replaced by a molybdenum carbide resistance furnace or a tilting induction furnace.
  • the charge intended to be arranged in the crucible is advantageously compacted before passing into the oven, to promote induction.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Adornments (AREA)
  • Powder Metallurgy (AREA)

Abstract

The invention relates to a piece of jewellery or timepiece that comprises a solid gold alloy having a white colour and is at least 14 karats. This piece includes gold combined with at least one refractory metal selected from the refractory metals of columns IVB, VB and VIB of the periodic table, preferably selected from chromium, niobium, vanadium, tantalum, titanium, zirconium and hafnium.

Description

Pièce de bijouterie ou d'horlogerie en alliage d'or massif, de couleur blanche, éclatante dans toute la masse. Jewelery or clockwork piece in solid gold alloy, white in color, radiant in the whole mass.
Domaine technique de l'inventionTechnical field of the invention
L'invention concerne une pièce de bijouterie, d'horlogerie ou de joaillerie comportant un alliage d'or massif, de couleur blanche, titrant au moins 14 carats et son procédé d'élaboration.The invention relates to a piece of jewelery, timepieces or jewelery comprising a solid gold alloy, white color, titrating at least 14 carats and its production process.
État de la techniqueState of the art
Les alliages à base d'or ont fait l'objet de très nombreuses recherches pour leur conférer des propriétés particulières et en particulier pour leur conférer une couleur particulière, une dureté, une usinabilité et une biocompatibilité améliorées.The gold-based alloys have been the subject of much research to give them special properties and in particular to give them a particular color, hardness, machinability and improved biocompatibility.
Concernant la couleur, en dehors des aspects « doré jaune » et « doré rouge » bien connus, les métallurgistes ont cherché à obtenir du rouge, du bleu et du noir, en jouant parfois sur la coloration superficielle (demande de brevet JP3166327). Dans la demande internationale WO-A-0046413, des alliages d'or et d'aluminium de couleur violette ont été élaborés. Cependant, les alliages d'or et d'aluminium sont difficiles à synthétiser, du fait de la disparité de ces deux métaux et de l'oxydabilité de l'aluminium. On a d'ailleurs recours au frittage comme indiqué dans la demande de brevet JP- A-11264036. Les métallurgistes ont également cherché à augmenter la dureté de l'or, sans en altérer sa couleur, par des ajouts de métaux choisis parmi Al, Mg, Cu, Ag, Zn, Ru, Co, Si, Mn, Fe, Ni, Pd, In, Sn, Sb, Pb, Bi, etc..Regarding the color, apart from the well-known "walleye" and "gold-red" aspects, the metallurgists have sought to obtain red, blue and black, sometimes playing on the superficial coloration (patent application JP3166327). In the international application WO-A-0046413, alloys of gold and aluminum of violet color have been developed. However, gold and aluminum alloys are difficult to synthesize due to the disparity of these two metals and the oxidability of aluminum. Sintering is also used as indicated in patent application JP-A-11264036. Metallurgists have also sought to increase the hardness of gold, without altering its color, by additions of metals selected from Al, Mg, Cu, Ag, Zn, Ru, Co, Si, Mn, Fe, Ni, Pd. , In, Sn, Sb, Pb, Bi, etc.
Certaines demandes de brevet, en particulier celles de la société SEIKO (JP- A-4183836, JP-A-4147931 , J P- A-3166328), citent un très grand nombre de métaux de la classification périodique utilisés comme additifs à l'or. Cependant, de tels additifs sont mélangés à de la poudre d'or, le mélange est, ensuite, compressé et fritte, avant d'être traité en surface pour recevoir une couche formée à partir de borax ou de carbure de bore, une couche oxydée ou une couche nitrurée. Les additifs se combinent alors avec le bore, l'oxygène ou le nitrure pour changer, en surface, la couleur de l'alliage et durcir en surface.Certain patent applications, in particular those of the company SEIKO (JP-A-4183836, JP-A-4147931, JP-A-3166328), cite a very large number of metals of the periodic table used as additives to the gold. However, such additives are mixed with gold powder, the mixture is then compressed and sintered, before being surface treated to receive a layer formed from borax or boron carbide, an oxidized layer or a nitrided layer. The additives then combine with boron, oxygen or nitride to change the surface of the alloy color and harden on the surface.
Ainsi, on peut dire que la plupart des alliages à base d'or actuels, durcis et colorés dans leur masse et non en surface, comprennent les métaux suivants : Cu, Ag, Pd, Ir et Al. Le zinc est également mentionné pour donner une couleur jaune (voir EP-A-0539702), mais il faut souligner que cet élément est très corrodable et n'est pas biocompatible.Thus, it can be said that most of the current gold-based alloys, hardened and colored in their mass and not at the surface, include the following metals: Cu, Ag, Pd, Ir and Al. Zinc is also mentioned to give a yellow color (see EP-A-0539702), but it should be emphasized that this element is very corrodable and is not biocompatible.
Des alliages dits alliages << blancs », à base d'indium, de gallium, d'étain sont souvent utilisés pour faire des brasures ou des matériaux spéciaux pour l'optoélectronique, mais ils sont cassants.Alloys called "white" alloys, based on indium, gallium, tin are often used to make solders or special materials for optoelectronics, but they are brittle.
Aujourd'hui, la bijouterie a éliminé le nickel, des ors dits « gris » pour le remplacer par le palladium. Ces alliages à base de palladium ayant tendance à jaunir, on corrige ce défaut par un traitement superficiel en déposant une mince couche de rhodium (< 0.5 μm) qui est beaucoup plus dur que l'or. L'effet est excellent, blanc et brillant, mais cette couche s'use et l'aspect jauni réapparaît, ce qui nécessite un service après-vente conséquent. Objet de l'inventionToday, the jewelery has eliminated nickel, so-called "gray" golds to replace it with palladium. As these palladium-based alloys have a tendency to turn yellow, this defect is corrected by a superficial treatment by depositing a thin layer of rhodium (<0.5 μm) which is much harder than gold. The effect is excellent, white and shiny, but this layer wears and the yellowed appearance reappears, which requires a consequent after-sales service. Object of the invention
L'invention a pour but une pièce de bijouterie, d'horlogerie ou de joaillerie en alliage d'or massif d'or, de couleur blanche, éclatante dans toute sa masse et non ternissable. De plus, la pièce à base d'or est plus particulièrement usinable, non cassante, d'une dureté supérieure à 200HV et biocompatible.The object of the invention is a piece of jewelery, timepieces or jewelery made of solid golden gold alloy, of white color, radiant in all its mass and not tarnishable. In addition, the gold-based part is more particularly machinable, non-brittle, with a hardness greater than 200HV and biocompatible.
Selon l'invention, ce but est atteint par le fait que la pièce comprend de l'or combiné à au moins un métal réfractaire sélectionné parmi les métaux réfractaires des colonnes IVB1 VB et VIB de la classification périodique.According to the invention, this object is achieved by the fact that the piece comprises gold combined with at least one refractory metal selected from the refractory metals of columns IVB 1 VB and VIB of the periodic table.
Selon un développement de l'invention, le métal réfractaire est choisi parmi le chrome, le niobium, le vanadium, le tantale, le zirconium et l'hafnium.According to a development of the invention, the refractory metal is selected from chromium, niobium, vanadium, tantalum, zirconium and hafnium.
Selon un mode de réalisation préférentiel, l'alliage comporte au moins un métal additionnel choisi parmi l'étain, l'indium, le galium et le germanium.According to a preferred embodiment, the alloy comprises at least one additional metal selected from tin, indium, galium and germanium.
L'invention a également pour but un procédé d'élaboration, simple et facile à mettre en œuvre, d'une telle pièce.Another object of the invention is to provide a method of making such a part simple and easy to implement.
Selon l'invention, ce but est atteint par le fait qu'une charge comportant au moins l'or et le métal réfractaire, est disposée sous une forme divisée grossièrement, dans un creuset réfractaire, avant d'être placée dans un four, sous atmosphère neutre, pour y être fondue, l'alliage fondu résultant étant ensuite coulé rapidement dans un moule en cuivre refroidi, ayant la forme de la pièce.According to the invention, this object is attained by the fact that a charge comprising at least gold and the refractory metal, is arranged in a roughly divided form, in a refractory crucible, before being placed in an oven, under Neutral atmosphere, to be melted, the resulting molten alloy is then quickly poured into a chilled copper mold, having the shape of the piece.
Selon un développement particulier, le four peut être un four à induction basculant, la charge ayant été préalablement compactée pour favoriser l'induction. Description de modes particuliers de réalisationAccording to a particular development, the oven may be a tilting induction furnace, the load having been previously compacted to promote induction. Description of particular embodiments
Dans la pièce de bijouterie, d'horlogerie et de joaillerie comprenant un alliage à base d'or, massif et titrant au moins à 50% en poids d'or (en particulier à 14 carats) et de préférence à 75% d'or (soit 18 carats), l'or est combiné avec un ou plusieurs métaux réfractaires sélectionnés parmi :In the piece of jewelery, timepieces and jewelery comprising a gold-based alloy, solid and grading at least 50% by weight of gold (in particular 14 carats) and preferably at 75% of gold (18 carats), gold is combined with one or more refractory metals selected from:
- les métaux réfractaires des colonnes IVB, VB et VIB de la classification périodique- the refractory metals of columns IVB, VB and VIB of the Periodic Table
- plus particulièrement parmi le chrome, le vanadium, le niobium, le tantale, le titane, le zirconium, et l'hafnium- more particularly among chromium, vanadium, niobium, tantalum, titanium, zirconium, and hafnium
- et, encore plus avantageusement, parmi le chrome et le niobium, car ces deux éléments permettent d'obtenir une meilleure fusibilité, compte tenu de l'existence de solutions solides étendues entre l'or et ces deux métaux. L'alliage peut ainsi, avantageusement, être un alliage binaire or/niobium comportant au moins 62% d'or (soit au moins 14 carats) ou un alliage binaire or/chrome comportant au moins 18% de chrome.and, even more advantageously, among chromium and niobium, since these two elements make it possible to obtain better fusibility, given the existence of extensive solid solutions between gold and these two metals. The alloy can thus advantageously be a binary gold / niobium alloy comprising at least 62% of gold (ie at least 14 carats) or a binary gold / chromium alloy containing at least 18% of chromium.
L'alliage peut également comporter un métal additionnel choisi parmi l'étain, l'indium, le gallium et le germanium. Ainsi, avantageusement, l'alliage peut comporter un métal réfractaire choisi parmi le niobium, le chrome et le vanadium et un métal additionnel choisi parmi l'étain et l'indium.The alloy may also comprise an additional metal selected from tin, indium, gallium and germanium. Thus, advantageously, the alloy may comprise a refractory metal selected from niobium, chromium and vanadium and an additional metal selected from tin and indium.
De tels alliages comprenant des métaux très réfractaires présentent la particularité de conférer à la pièce de bijouterie ou d'horlogerie un aspect esthétique particulier c'est-à-dire une couleur blanche, éclatante sur toute leur masse, sans nécessiter de traitement de surface ultérieure, tout en ayant des propriétés mécaniques très intéressantes, notamment en ce qui concerne les possibilités d'usinage. Ces pièces ayant de telles propriétés mécaniques et esthétiques sont, en particulier, utilisées dans le domaine de la bijouterie, la joaillerie et l'horlogerie.Such alloys comprising highly refractory metals have the particularity of giving the piece of jewelery or watchmaking a particular aesthetic appearance, ie a white color, radiant over their entire mass, without the need for subsequent surface treatment. , while having very interesting mechanical properties, particularly as regards the machining possibilities. These parts having such properties mechanical and aesthetic are, in particular, used in the field of jewelery, jewelery and watchmaking.
Parmi les métaux réfractaires susceptibles d'être alliés à l'or, le niobium, le chrome, le vanadium et le titane sont avantageusement choisis car les systèmes binaires Au-Nb, Au-V et Au-Ti peuvent former des alliages ayant des transformations allotropiques à l'état solide.Among the refractory metals capable of being alloyed with gold, niobium, chromium, vanadium and titanium are advantageously chosen because the Au-Nb, Au-V and Au-Ti binary systems can form alloys having transformations. allotropic in the solid state.
En effet, le système binaire Au-Nb à 25% de Nb en poids forme, entre 9200C et 14200C, une solution solide homogène. À 9200C, on se trouve à la composition d'un eutectoïde, qui se transforme en deux fins précipités de composés définis Au2Nb et Au2Nb3. Cet alliage peut donc par un simple traitement thermique, (recuit à 10000C et trempe), être retransformé en solution solide continue.Indeed, the Au-Nb binary system at 25% Nb by weight forms, between 920 ° C. and 1420 ° C., a homogeneous solid solution. At 920 ° C., it is the composition of a eutectoid, which is converted into two fine precipitates of compounds defined in Au 2 Nb and Au 2 Nb 3 . This alloy can therefore by a simple heat treatment, (annealing at 1000 ° C. and quenching), be converted back into a continuous solid solution.
L'exemple 1 ci-dessous illustre la mise en évidence de la diffusion du niobium dans l'or. Il a, en effet, été constaté, de façon surprenante, qu'en mettant accidentellement en contact de l'or fondu avec du niobium (une goutte d'or déposée sur un disque de niobium à 15000C), les deux métaux réagissaient pour former localement un alliage blanc ayant un très bel aspect et présentant une résistance mécanique élevée.Example 1 below illustrates the demonstration of the diffusion of niobium in gold. It has, in fact, been found, surprisingly, that by accidentally contacting molten gold with niobium (a drop of gold deposited on a niobium disk at 1500 ° C.), the two metals reacted to form locally a white alloy having a very good appearance and having a high mechanical strength.
Exemple 1 :Example 1
De l'or pur a été déposé dans un trou non débouchant, pratiqué dans une rondelle épaisse en niobium. La rondelle comportant l'or a été portée à 15000C, sous atmosphère neutre, dans un four à résistance de carbure de silicium. Il a résulté, de cette opération, la formation d'un alliage blanc au cœur de la rondelle et il a été constaté que le niobium solide, réputé pour diffuser très lentement, s'était combiné parfaitement à l'or liquide. Ainsi, l'exemple 2 ci-dessous illustre l'élaboration d'un alliage binaire or- niobium à 18 carats.Pure gold was deposited in a non-through hole made in a thick niobium washer. The gold-bearing washer was heated to 1500 ° C., under a neutral atmosphere, in a silicon carbide resistance furnace. The result of this operation was the formation of a white alloy in the center of the puck and it was found that the solid niobium, known to diffuse very slowly, combined perfectly with the liquid gold. Thus, Example 2 below illustrates the development of an 18-carat gold-binary alloy.
Exemple 2 :Example 2
Une charge comportant 400 g d'or en grenaille et 127 g de poudre de niobium, divisée grossièrement, a été placée dans un creuset en alumine, dans le même four et les mêmes conditions que l'exemple 1. L'alliage fondu a été ensuite coulé rapidement dans un moule en cuivre refroidi, ayant la forme de la pièce.A filler comprising 400 g of shot gold and 127 g of coarsely divided niobium powder was placed in an alumina crucible, in the same oven and under the same conditions as in Example 1. The molten alloy was then quickly poured into a chilled copper mold, having the shape of the piece.
Il en résulte un alliage caractérisé par une couleur blanche classifiée selon l'échelle Lab : L=68.5, a=1.21 , b=5.02.The result is an alloy characterized by a white color classified according to the Lab scale: L = 68.5, a = 1.21, b = 5.02.
Dans le modèle colorimétrique, une couleur est, en effet, repérée par trois valeurs :In the color model, a color is, in fact, identified by three values:
L1 la luminance, exprimée en pourcentage (0 pour le noir à 100 pour le blanc) a et b deux gammes de couleur allant respectivement du vert au rouge et du bleu au jaune avec des valeurs allant de -120 à +120.L 1 the luminance, expressed as a percentage (0 for black to 100 for white) has and b two color ranges from green to red and blue to yellow respectively, with values ranging from -120 to +120.
Le mode Lab couvre ainsi l'intégralité du spectre visible par l'oeil humain et le représente de manière uniforme. Il permet donc de décrire l'ensemble des couleurs visibles.The Lab mode thus covers the entire spectrum visible to the human eye and represents it in a uniform manner. It allows to describe all visible colors.
La dureté de l'alliage est de 337 Hv0.3 et il a été constaté que cet alliage pouvait être usiné par des outils conventionnels : tour, fraise équipés d'outils en carbure.The hardness of the alloy is 337 Hv0.3 and it was found that this alloy could be machined by conventional tools: lathe, cutter equipped with carbide tools.
D'autres alliages à base d'or d'une belle couleur blanche et ayant des propriétés mécaniques très intéressantes, notamment, en ce qui concerne les possibilités d'usinage peuvent être formés avec des métaux très réfractaires tels que V, Ta, Ti, Zr et Hf et de préférence Cr.Other alloys based on gold of a beautiful white color and having very interesting mechanical properties, in particular, as far as the machining possibilities can be formed with highly refractory metals such as V, Ta, Ti, Zr and Hf and preferably Cr.
Ainsi, l'alliage binaire Au-Cr donne en se refroidissant deux phases, α' et Cr, dont la quantité de α' représente 55% atomique du total. En revanche, si on trempe l'alliage liquide à 1432°C, on obtient deux phases : >> Solution solide riche en or à 18% de chrome (en atomes), »- Solution solide riche en chrome à 9% d'or (en atomes), cette dernière solution solide étant minoritaire (18% du total). L'alliage peut également être un alliage binaire composé d'au moins 58,35% d'or (14 carats) et de chrome.Thus, the Au-Cr binary alloy gives, by cooling, two phases, α 'and Cr, whose amount of α' represents 55 atomic% of the total. However, if the liquid alloy is quenched to 1432 ° C, two phases are obtained:>> solid solution rich gold to 18% of chromium (atomic) "- A solid solution rich in chromium to 9% gold (in atoms), this last solid solution being minority (18% of the total). The alloy may also be a binary alloy composed of at least 58.35% gold (14 karat) and chromium.
L'alliage binaire Au-V à 75% d'or fond à 1430°C, il se solidifie en formant deux phases, une solution solide homogène ayant la structure de l'or et un composé défini V3Au représentant 21 % en fraction molaire.The Au-V binary alloy at 75% gold melts at 1430 ° C, it solidifies forming two phases, a homogeneous solid solution having the structure of gold and a defined V 3 Au compound representing 21% fraction molar.
L'alliage peut également comporter deux métaux réfractaires, ce qui fait varier les propriétés physiques, mais permet de conserver la blancheur qui est variable dans le modèle colorimétrique La*b* (aussi connu sous le nom de CIELab), entre de préférence (a ≤ 3 ; b ≤ 8) et de préférence (a ≤ 1 ; b ≤ 3).The alloy may also have two refractory metals, which varies the physical properties, but allows to maintain the whiteness which is variable in the color model La * b * (also known as CIELab), preferably between ≤ 3, b ≤ 8) and preferably (a ≤ 1, b ≤ 3).
L'alliage peut également être constitué par un alliage ternaire, comportant par exemple de l'or, du niobium et du chrome. Il peut comporter au moinsThe alloy may also be constituted by a ternary alloy, comprising, for example, gold, niobium and chromium. It may include at least
Cr 58,35 % d'or (soit 14 carats) et la valeur du rapport — entre le pourcentageCr 58.35% gold (14 carats) and the value of the ratio - between the percentage
Nb atomique de chrome et le pourcentage atomique de niobium peut être égale à 1 (eutectique Nb/Cr), et à 2 (composé défini Cr2Nb), mais toutes les proportions sont intéressantes et notamment la valeur 7,33 qui correspond à l'eutectique Cr/Nb riche en chrome. De plus, la brillance des alliages peut être contrôlée et/ou modifiée, par l'adjonction d'un ou plusieurs métaux additionnels, très fusibles et très « blancs », tels que le gallium, l'indium, l'étain et le germanium et avantageusement l'étain et l'indium et encore plus particulièrement l'étain, qui a plus d'affinités que In pour le chrome, le niobium et le vanadium.Atomic number of chromium and the atomic percentage of niobium may be equal to 1 (Nb / Cr eutectic), and to 2 (defined compound Cr 2 Nb), but all the proportions are interesting and in particular the value 7.33 which corresponds to 1 Cr / Nb eutectic rich in chromium. In addition, the brightness of the alloys can be controlled and / or modified, by the addition of one or more additional metals, highly fusible and very "white", such as gallium, indium, tin and germanium and advantageously tin and indium and even more particularly tin, which has more affinities than In for chromium, niobium and vanadium.
L'exemple 3 illustre ci-dessous la production d'un alliage ternaire or-niobium- indium à 18 carats.Example 3 below illustrates the production of an 18-carat gold-niobium-indium ternary alloy.
Exemple 3 :Example 3
Alliage selon l'exemple 2 traité thermiquement par des recuits opérés à 1200°C et 800°C suivis de trempes pour faire varier la proportion de solution solide homogène. L'influence de ces traitements est appréciée par les diffractogrammes effectués et par des mesures de dureté. La solution solide a une dureté Hv comprise entre 250 et 337, alors que le domaine à 2 phases Au2Nb et Au2Nb3 a une dureté supérieure à 600Hv.Alloy according to Example 2 heat-treated by annealing performed at 1200 ° C. and 800 ° C. followed by tempering to vary the proportion of homogeneous solid solution. The influence of these treatments is appreciated by the diffractograms made and hardness measurements. The solid solution has a hardness Hv between 250 and 337, while the 2-phase domain Au2Nb and Au2Nb3 has a hardness greater than 600Hv.
Après recuit à 1200°C et trempe à l'eau ou à l'huile, on constate que l'alliage est constitué principalement d'une solution solide d'or, les pics sur le diffractogramme sont légèrement décalés par rapport à ceux de l'or pur. Au cours du recuit à 800°C pendant 30min, de nouvelles phases se forment, notamment Au2Nb et Au2Nb3, la solution solide d'or est toujours présente. Dans le but de précipiter totalement la solution d'or, le temps de recuit a été augmenté. Un traitement thermique à 12000C pendant 2 H suivi d'un recuit à 8000C pendant 12 H ont été réalisés.After annealing at 1200 ° C. and quenching with water or oil, it is found that the alloy consists mainly of a solid solution of gold, the peaks on the diffractogram are slightly offset from those of pure gold. During annealing at 800 ° C for 30min, new phases are formed, including Au2Nb and Au2Nb3, the gold solid solution is still present. In order to completely precipitate the gold solution, the annealing time has been increased. Heat treatment at 1200 ° C. for 2 hours followed by annealing at 800 ° C. for 12 hours was carried out.
On constate alors que lorsqu'on augmente le temps de recuit, la solution solide d'or disparaît au profit de la phase Au2Nb, mais reste néanmoins présente. L'alliage peut également être un alliage quaternaire or/niobium/étain/indium composé, par exemple, en proportions massiques de 75% d'or, de 7% de niobium, de 9,1% d'indium et de 8,9% d'étain. Les proportions d'étain et d'indium dans cet alliage quaternaire correspondent à la composition eutectique du binaire Sn-In.It can be seen that when increasing the annealing time, the solid gold solution disappears in favor of the Au2Nb phase, but nevertheless remains present. The alloy may also be a quaternary gold / niobium / tin / indium compound compound, for example, in mass proportions of 75% gold, 7% niobium, 9.1% indium and 8.9% by weight. % tin. The proportions of tin and indium in this quaternary alloy correspond to the eutectic composition of the Sn-In binary.
Par ailleurs, il est possible d'obtenir des alliages ayant un aspect blanc variant entre la couleur des alliages à base d'or et de palladium et celle des alliages de bijouterie à base d'or et d'indium à 75% d'or.Furthermore, it is possible to obtain alloys having a white appearance varying between the color of gold-based alloys and palladium and that of jewelery alloys based on gold and indium at 75% gold. .
En effet, un alliage ternaire or/nobium/indium composé de 75% d'or, de 18% d'indium et de 7% de niobium a une couleur équivalente à celle de l'or palladium rhodié. De même, un alliage ternaire or/niobium/étain composé de 75% d'or, de 18% d'étain et de 7% de niobium a une couleur blanche plus claire que celle du platine utilisé en bijouterie. À titre de comparaison, la couleur de l'acier 316L inoxydable se situe, par exemple, entre celle du platine de bijouterie et celle de l'or-palladium rhodié.Indeed, a ternary alloy gold / nobium / indium composed of 75% gold, 18% indium and 7% niobium has a color equivalent to that of rhodium palladium gold. Similarly, a gold / niobium / tin ternary alloy composed of 75% gold, 18% tin and 7% niobium has a lighter white color than platinum used in jewelery. For comparison, the color of 316L stainless steel is, for example, between that of platinum jewelery and that of gold-palladium rhodium.
Les pièces de bijouterie ou d'horlogerie comportant ces alliages à base d'or selon l'invention présentent l'avantage d'être massif, de couleur blanche sur toute leur masse, avec avantageusement une dureté, une biocompatibilité, une usinabilité et un éclat métallique améliorés. Le blanc est brillant et éclatant sur toute la masse de l'alliage et pas uniquement en surface. De plus, de tels alliages ne font intervenir aucun élément d'addition, susceptible de provoquer un ternissement de la pièce, c'est-à-dire des métaux oxydables, tels que le fer ou le manganèse ou des métaux pouvant se ternir comme l'argent.The jeweler or watchmaking pieces comprising these gold-based alloys according to the invention have the advantage of being solid, of a white color throughout their mass, with advantageously a hardness, a biocompatibility, a machinability and a sparkle. improved metal. The white is shiny and brilliant on all the mass of the alloy and not only on the surface. In addition, such alloys do not involve any additive element, likely to cause tarnishing of the workpiece, that is to say oxidizable metals, such as iron or manganese or metals that can tarnish as well. 'money.
Ainsi, grâce à la présente invention, des alliages à base d'or ayant des caractéristiques colorimétriques très intéressantes dans le blanc éclatant et dans toute leur masse, des duretés comprises entre 200 et 500Hv, fondant de préférence entre 1100 et 1500 0C peuvent être proposés. De plus, tous ces alliages sont biocompatibles et peuvent être usinés mécaniquement permettant de réaliser des formes diverses et variées.Thus, thanks to the present invention, gold-based alloys having very interesting colorimetric characteristics in bright white and in all their mass, hardnesses between 200 and 500Hv, melting preferably between 1100 and 1500 0 C may be proposed. In addition, all these alloys are biocompatible and can be machined mechanically to achieve various forms and varied.
L'invention n'est pas limitée aux modes de réalisation décrits ci-dessus. Ainsi, le four à résistance de carbure de silicium mentionné dans les exemples 1 à 4 pourrait avantageusement être remplacé par un four à résistance de carbure de molybdène ou par un four à induction basculant. Dans le cas d'un four à induction basculant, la charge destinée à être disposée dans le creuset est, avantageusement, compactée avant le passage dans le four, afin de favoriser l'induction. The invention is not limited to the embodiments described above. Thus, the silicon carbide resistor furnace mentioned in Examples 1 to 4 could advantageously be replaced by a molybdenum carbide resistance furnace or a tilting induction furnace. In the case of a tilting induction furnace, the charge intended to be arranged in the crucible is advantageously compacted before passing into the oven, to promote induction.

Claims

Revendications claims
1. Pièce de bijouterie, de joaillerie ou d'horlogerie comportant un alliage d'or massif, de couleur blanche titrant au moins 14 carats, caractérisé en ce que l'alliage comprend de l'or combiné à au moins un métal réfractaire sélectionné parmi les métaux réfractaires des colonnes IVB, VB et VIB de la classification périodique.1. A piece of jewelery, jewelery or timepieces comprising a solid gold alloy, of white color grading at least 14 carats, characterized in that the alloy comprises gold combined with at least one refractory metal selected from the refractory metals of columns IVB, VB and VIB of the Periodic Table.
2. Pièce selon la revendication 1 , caractérisé en ce que l'alliage titre à 18 carats.2. Part according to claim 1, characterized in that the title alloy to 18 karat.
3. Pièce selon l'une des revendications 1 et 2, caractérisé en ce que le métal réfractaire est choisi parmi le niobium, le vanadium, le tantale, le titane, le zirconium et l'hafnium.3. Part according to one of claims 1 and 2, characterized in that the refractory metal is selected from niobium, vanadium, tantalum, titanium, zirconium and hafnium.
4. Pièce selon l'une quelconque des revendications 1 à 2, caractérisé en ce que l'alliage est un alliage ternaire or/niobium/chrome comportant au moins 58,35% d'or.4. Part according to any one of claims 1 to 2, characterized in that the alloy is a ternary alloy gold / niobium / chromium having at least 58.35% gold.
5. Pièce selon l'une quelconque des revendications 1 à 3, caractérisé en ce que l'alliage comporte au moins un métal additionnel choisi parmi l'étain, l'indium, le gallium et le germanium.5. Part according to any one of claims 1 to 3, characterized in that the alloy comprises at least one additional metal selected from tin, indium, gallium and germanium.
6. Pièce selon l'une quelconque des revendications 1 à 3, caractérisé en ce que l'alliage est un alliage binaire or/niobium comportant au moins 62% d'or. 6. Part according to any one of claims 1 to 3, characterized in that the alloy is a binary gold / niobium alloy having at least 62% gold.
7. Procédé d'élaboration d'une pièce selon l'une quelconque des revendications 1 à 10, caractérisé en ce qu'une charge comportant au moins l'or et le métal réfractaire est disposée sous une forme divisée grossièrement dans un creuset réfractaire, avant d'être placée dans un four sous atmosphère neutre, pour y être fondue, l'alliage fondu résultant étant ensuite coulé rapidement dans un moule en cuivre refroidi, ayant la forme de la pièce.7. A method of producing a part according to any one of claims 1 to 10, characterized in that a load comprising at least gold and the refractory metal is arranged in a roughly divided form in a refractory crucible, before being placed in a furnace under a neutral atmosphere for melting, the resulting molten alloy is then rapidly poured into a chilled copper mold, having the shape of the workpiece.
8. Procédé selon la revendication 11 , caractérisé en ce que le four est un four à résistance de carbure de silicium ou de molybdène.8. Method according to claim 11, characterized in that the furnace is a resistance furnace of silicon carbide or molybdenum.
9. Procédé selon la revendication 11 , caractérisé en ce que le four est un four à induction basculant, la charge ayant été préalablement compactée. 9. The method of claim 11, characterized in that the oven is a tilting induction furnace, the load having been previously compacted.
PCT/FR2008/001570 2007-11-12 2008-11-06 Piece of jewellery or timepiece made of solid gold alloy having a white colour, the entirety of which is shining WO2009092920A2 (en)

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