EP2347021A1 - Alliage d'or colore et procede de formation associe - Google Patents

Alliage d'or colore et procede de formation associe

Info

Publication number
EP2347021A1
EP2347021A1 EP09811780A EP09811780A EP2347021A1 EP 2347021 A1 EP2347021 A1 EP 2347021A1 EP 09811780 A EP09811780 A EP 09811780A EP 09811780 A EP09811780 A EP 09811780A EP 2347021 A1 EP2347021 A1 EP 2347021A1
Authority
EP
European Patent Office
Prior art keywords
gold alloy
method recited
gold
coloured
alloy
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.)
Withdrawn
Application number
EP09811780A
Other languages
German (de)
English (en)
Inventor
Peng Chum Loh
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AUTIUM Pte Ltd
Original Assignee
AUTIUM Pte Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from SG200806557-5A external-priority patent/SG160231A1/en
Application filed by AUTIUM Pte Ltd filed Critical AUTIUM Pte Ltd
Publication of EP2347021A1 publication Critical patent/EP2347021A1/fr
Withdrawn legal-status Critical Current

Links

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
    • 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 coloured gold alloys and method for forming the same.
  • the invention relates to coloured gold alloys having titanium content of more than 10 weight percent (wt%).
  • Gold jewellery and watches are common accessories not only for the status- conscious, but also for the fashion-goers.
  • Coloured gold alloys are becoming increasingly high in demand compared to traditional yellowish gold.
  • Such colourings on gold alloys include maroon, blue, green or greenish-blue, and black.
  • an alloy comprising gold and colouring elements are heated in an oxidizing atmosphere at a temperature between 700°C and 950 0 C for 20 to 60 minutes.
  • the resultant gold alloy is then cooled.
  • titanium is often included as one of the alloying elements.
  • the titanium-gold alloy possesses a coloured surface due to the formation of an intermetallic phase within the bulk of the gold alloy.
  • titanium oxide is formed at the surface of the gold alloy. Titanium oxide is brittle and deteriorates the mechanical properties of the gold alloys. Such oxide layers do not possess sufficient scratch resistance or durability for daily wear. Protection of the oxide layers is therefore needed.
  • little (less than 2 wt%) or no titanium is added as an alloying element. Mechanical properties of the resultant gold alloy is therefore compromised.
  • a method for forming coloured gold alloy comprises coating a layer of oil on a gold alloy and heating the coated gold alloy at a temperature selected based on the colouring on the gold alloy desired until the colouring appears.
  • the gold alloy comprises gold, titanium, and at least one other element.
  • the titanium content in the alloy is more than 10 wt%.
  • a coloured gold alloy comprising gold, titanium, and at least one other element formed in accordance with the first aspect of the invention.
  • jewellery comprising a coloured gold alloy comprising gold, titanium, and at least one other element formed in accordance with the first aspect of the invention.
  • a coloured gold alloy in jewellery, the coloured gold alloy comprising gold, titanium, and at least one other element formed in accordance with the first aspect of the invention.
  • the invention relates to coloured gold alloys and method for forming the same.
  • the invention relates to coloured gold alloys having titanium content of more than 10 weight percent (wt%).
  • the gold alloy preferably contains 58 - 85 wt% gold. This covers commercially termed 14 - 20 carat gold. Titanium forms one component of the alloy. Titanium is preferably present in at least 10 wt% of the gold alloy. Preferably, the titanium content does not exceed 50 wt%.
  • the balance of the gold alloy comprises at least one other element. The other element preferably aids in the machinability or castability of the resultant coloured gold alloy. More preferably, the other element acts as a deoxidizer, suppressing the formation of metallic oxides. Examples of the other element include the following:
  • a thin layer of oil is first coated on the gold alloy.
  • the thin layer of oil is coated on the entire exposed surface of the gold alloy.
  • the thin layer of oil includes, but not limited to, low viscosity oils such as olive oil, organic oil, lubricating oil, hydrocarbons.
  • the coating of the thin layer of oil over the gold alloy helps to minimize formation of undesirable metallic oxides on the gold alloy. Otherwise, the presence of the oxides on the surface of the gold alloy will cause poor surface finishing since oxides are brittle and give a rough-dimple surface appearance.
  • the coated gold alloy is then heated at a temperature selected based on the colouring on the gold alloy desired. The heating continues until the colouring appears.
  • the gold alloy is heated at temperatures between 400 0 C and 900 0 C, and in particular,
  • the desired colouring on the gold alloy starts to become visible.
  • the gold alloy continues to be heated until the selected temperature is reached whereby the desired colouring starts to stabilize on the gold alloy.
  • the gold alloy is heated in a non-oxidizing environment such as a carburizing environment providing carbon precursors to form carbonaceous layer on the surface of the gold alloy.
  • the carbonaceous layer may comprise carbides.
  • the gold alloy is heated using a carburizing flame consisting of an oxy-acetylene flame.
  • the flame is preferably acetylene- rich oxy-acetylene flame.
  • the carburizing flame is non-oxidizing.
  • the gold alloy is heated in open air on a hotplate or furnace.
  • Other heating sources apparent to a person skilled in the art are also suitable.
  • the hot gold alloy is allowed to cool to room temperature in still air to obtain the coloured gold alloy.
  • the hot gold alloy is rapidly quenched in a quenching medium to obtain the coloured gold alloy.
  • the gold alloy is preferably quenched at room temperature.
  • the quenching medium is a hydrocarbon medium.
  • the hydrocarbon medium is low viscosity oil.
  • the low viscosity oil is one of olive oil, organic oil or lubricating oil, or a mixture thereof.
  • Gold alloys are formed by conventional techniques such as electric arc melting.
  • the desired compositions of the gold alloy are mixed and melted in an inert atmosphere or under vacuum pressure.
  • Alloy 2 (18 carat gold) illustrated in Table 1 below
  • 75 wt% Au, 17 wt% Ti, 5 wt% Fe, 0.8 wt% Co, 0.5 wt% Cr, 1.5 wt% Al, and 0.2 wt% Si are mixed and melted in an induction argon atmosphere in a conventional crucible such as magnesium oxide crucible.
  • the melting may also be conducted in a conventional electric arc furnace with a graphite crucible.
  • the melted gold alloy flows into a casting mould and cooled to form the desired shape.
  • the cast gold alloy is subsequently grinded, polished and buffed to mirror-like finish so that the gold alloy surface is essentially contaminant-free.
  • Other melting techniques and finishing steps are also suitable for obtaining an essentially contaminant-free gold alloy surface.
  • the gold alloy is dipped into a bath of olive oil to coat a thin layer of olive oil on the gold alloy.
  • the gold alloy is next heated with an oxy-acetylene flame.
  • the selected temperature is set at 400 0 C to obtain a maroon coloured gold alloy.
  • the ratio of the volumetric flow rates of acetylene to oxygen is carefully controlled such that the flame is carburizing. In this example, the ratio is kept at 5:3. Other ratios are also suitable as long as there is excess acetylene in the flame.
  • the heating continues until a visible dull red or maroon appearance of the gold alloy is obtained. Heating is stopped at approximately 450 0 C and the gold alloy is allowed to cool to room temperature in still air. A resultant maroon coloured gold alloy is obtained.
  • the gold alloy in this example is formed in the same manner as described in Example 1 (i.e. Alloy 2). After the formation of gold alloy, the gold alloy is dipped into a bath of olive oil to coat a thin layer of olive oil on the gold alloy. The gold alloy is next heated on a hot-plate in open air. The selected temperature is set at 650 °C to produce greenish-blue coloured gold alloy.
  • the heating temperature approaches 500 0 C
  • the surface of the heated gold alloy gradually changes from maroon to slight bluish hue.
  • the bluish hue becomes more visible and stable.
  • the heating temperature approaches 650 °C
  • the surface of the heated gold alloy gradually changes from blue to greenish-blue. Heating is stopped at 650 0 C and the gold alloy is allowed to cool to room temperature in still air. A resultant greenish-blue coloured gold alloy is obtained.
  • the gold alloy in this example is formed in the same manner as described in Example 1 (i.e. Alloy 2). After the formation of gold alloy, the gold alloy is dipped into a bath of olive oil to coat a thin layer of olive oil on the gold alloy. The gold alloy is next heated with an oxy-acetylene flame at 900 0 C. The ratio of the volumetric flow rates of acetylene to oxygen is carefully controlled such that the flame is carburizing. In this example, the ratio is kept at 5:3. Other ratios are also suitable as long as there is excess acetylene in the flame.
  • the heating continues until a visible wetting appearance of the gold alloy is obtained. It takes approximately one minute at 900 0 C since heating begins for the visible wetting appearance to be observed.
  • the gold alloy is immediately quenched in an olive oil bath container at room temperature.
  • the bath container contains olive oil approximately fifty times larger in volume than the volume of the gold alloy.
  • the gold alloy when totally immersed in the olive oil bath container, is at least 15 mm below the olive oil level.
  • the high temperature may cause vapourization of the olive oil initially.
  • the excess olive oil ensures there are sufficient carbon particles to form carbonaceous layer on the surface of the gold alloy.
  • the olive oil bath container is exposed to air. Oxygen may be present at the olive oil surface. By having the gold alloy immersed at least 15 mm below the olive oil level, oxidation of the gold alloy is minimized. Further, any oxides inevitably formed on the gold alloy surface may be reduced.
  • the gold alloy obtained in this manner is black in colour.
  • Table 1 illustrates the exemplary compositions of 14 - 20 carat gold alloy suitable for the working of the invention.
  • the carbonaceous composition in the metallic carbonaceous layer may include, but not limited to, carbides. Besides liberating free carbon particles, the intermediate zone also serves to reduce some of the metallic oxides inevitably formed during the heating.
  • Oxides are inevitably formed on the surface of the gold alloy since there is a window period between the formation of the gold alloy and the heating step. Active elements such as titanium easily oxidize to form titanium oxides. The formation of oxides is even more prominent and severe during heating on a hot- plate in open air or other similar oxidizing environments. To minimize the formation of oxides, it is therefore critical to coat a thin layer of oil on the gold alloy surface prior to the heating.
  • the layer of oil will act as a diffusion barrier for atmospheric oxygen adsorbing onto the gold alloy surface and diffusing from the surface to the inner gold alloy, thereby preventing excessive oxidation.
  • the thin layer of oil also serves another advantage. By having the thin layer of oil over the gold alloy surface, an even heating can be achieved so that localized hot spots at different regions of the gold alloy are avoided.
  • the afore-described method provides a simple and economical way of producing blue, green or greenish-blue, maroon and black gold alloys using a single alloy composition.
  • coloured gold alloys are obtained.
  • Conventional induction and electric arc furnaces are commercially available for melting and forming different compositions gold alloys.
  • Oxy-acetylene torches are also commercially available for carburizing the gold alloy.
  • Low viscosity oils such as olive oil, organic oil and lubricating oil are cheaply available and can be reused and recycled. Scalability to production stage is also easily achieved since the method involves non-sophisticated equipments.
  • about 10 - 20 grams of coloured gold alloy can be formed in relatively short time of less than one minute of heating at the selected temperature.
  • the coloured gold alloy obtained via the afore-described method is subsequently light-polished to produce an intense, glossy coloured surface.
  • the colouring formed on the gold alloy surface is physically and chemically stable for daily use.
  • the colouring does not deteriorate over time. This is due to the formation of a carbonaceous layer on the gold alloy surface.
  • the carbonaceous layer has good interface adhesion with the underlying gold alloy.
  • the dense carbonaceous layer provides a scratch-resistant layer protecting the underlying gold alloy, and provides sufficient corrosion resistance against body acids for daily use, which makes the gold alloy suitable for use in jewellery and watch parts.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Adornments (AREA)
  • Resistance Heating (AREA)
  • Other Surface Treatments For Metallic Materials (AREA)

Abstract

L'invention concerne un procédé de formation d'un alliage d'or coloré. Ce procédé consiste à déposer une couche d'huile sur un alliage d'or et à chauffer ledit alliage revêtu à une température déterminée en fonction de la coloration d'alliage souhaitée, jusqu'à ce que cette coloration apparaisse. L'alliage en or contient de l'or, du titane et au moins un autre élément. La teneur en titane de l'alliage est supérieure à 10% en poids.
EP09811780A 2008-09-08 2009-07-14 Alliage d'or colore et procede de formation associe Withdrawn EP2347021A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SG200806557-5A SG160231A1 (en) 2008-09-08 2008-09-08 Method of forming a metallic carbide layer on a gold alloy
SG200809138-1A SG160266A1 (en) 2008-09-08 2008-12-11 Coloured gold alloy and method for forming the same
PCT/SG2009/000249 WO2010027329A1 (fr) 2008-09-08 2009-07-14 Alliage d'or colore et procede de formation associe

Publications (1)

Publication Number Publication Date
EP2347021A1 true EP2347021A1 (fr) 2011-07-27

Family

ID=41797332

Family Applications (1)

Application Number Title Priority Date Filing Date
EP09811780A Withdrawn EP2347021A1 (fr) 2008-09-08 2009-07-14 Alliage d'or colore et procede de formation associe

Country Status (3)

Country Link
EP (1) EP2347021A1 (fr)
SG (1) SG160266A1 (fr)
WO (1) WO2010027329A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3040790A1 (fr) * 2014-12-29 2016-07-06 Montres Breguet S.A. Pièce d'horlogerie ou de bijouterie en alliage précieux léger à base de titane
CN111286641B (zh) * 2020-02-26 2021-11-30 深圳市粤豪珠宝有限公司 一种抗变色玫瑰金用补口合金及其制备方法和应用
EP4026923A1 (fr) * 2021-01-07 2022-07-13 Officine Panerai AG Alliage à base de titane et d'or

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02185932A (ja) * 1989-01-12 1990-07-20 Agency Of Ind Science & Technol 黒色化した金合金製品及びその製造方法
JPH02225655A (ja) * 1989-02-28 1990-09-07 Agency Of Ind Science & Technol 光沢のある黒色に着色する金合金とその着色法
US5139739A (en) * 1989-02-28 1992-08-18 Agency Of Industrial Science And Technology Gold alloy for black coloring, processed article of black colored gold alloy and method for production of the processed article
JPH0757905B2 (ja) * 1989-07-21 1995-06-21 東芝タンガロイ株式会社 金色装飾品
JPH03100158A (ja) * 1989-09-12 1991-04-25 Agency Of Ind Science & Technol 光輝ある黒色に着色した金合金とその着色法
JPH0717974B2 (ja) * 1990-11-28 1995-03-01 工業技術院長 光沢のある灰黒色及び黒色に着色する金合金とその着色法
JP2005298832A (ja) * 2002-02-08 2005-10-27 Matsuda Sangyo Co Ltd カラー金合金

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2010027329A1 *

Also Published As

Publication number Publication date
SG160266A1 (en) 2010-04-29
WO2010027329A1 (fr) 2010-03-11

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