EP0672489A1 - Titanium based article with high hardness and high gloss process for preparing and process for hardening and colouring the surface of this article - Google Patents

Titanium based article with high hardness and high gloss process for preparing and process for hardening and colouring the surface of this article Download PDF

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Publication number
EP0672489A1
EP0672489A1 EP95103385A EP95103385A EP0672489A1 EP 0672489 A1 EP0672489 A1 EP 0672489A1 EP 95103385 A EP95103385 A EP 95103385A EP 95103385 A EP95103385 A EP 95103385A EP 0672489 A1 EP0672489 A1 EP 0672489A1
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European Patent Office
Prior art keywords
article
titanium
temperature
elements
mixture
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.)
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EP95103385A
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German (de)
French (fr)
Inventor
Thomas Gladden
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Asulab AG
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Asulab AG
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Priority claimed from CH81494A external-priority patent/CH687622A5/en
Priority claimed from FR9404221A external-priority patent/FR2718376B1/en
Application filed by Asulab AG filed Critical Asulab AG
Publication of EP0672489A1 publication Critical patent/EP0672489A1/en
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
    • C22C32/0047—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with carbides, nitrides, borides or silicides as the main non-metallic constituents
    • 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
    • B22F3/001—Starting from powder comprising reducible metal compounds
    • 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
    • C22C1/10—Alloys containing non-metals

Definitions

  • the invention relates to an article based on titanium, in particular a decorative article such as a piece of clothing for the watch industry, having a high hardness and which, once polished, has a surface of intense gloss, as well as 'A method of manufacturing such an article, by sintering a mixture of titanium hydride powder (TiH2) and specific addition elements.
  • TiH2 titanium hydride powder
  • the invention also relates to a method for hardening and coloring a surface of such an article.
  • the cladding parts for watchmaking such as cases, middle parts, bracelet links, watch dials or the like, with high hardness and high gloss, are produced from austenitic stainless steels.
  • austenitic stainless steels One of the main reasons for this choice is that this type of steel can be easily stamped or stamped.
  • nickel As well as cobalt are highly allergenic constituents capable of contaminating the wearer's skin, so that many countries have set up standards prohibiting the sale of articles in permanent contact with the skin, susceptible to such contamination. , especially by nickel.
  • Hard articles are also known which are made from titanium carbide or tungsten carbide.
  • these articles cannot be sintered without using a binder if they are to maintain good toughness.
  • the currently known binders are allergenic so that the articles thus obtained are also likely to contaminate the skin of the carriers and therefore subject to the same restrictions of use as the articles based on austenitic steel mentioned above.
  • the main object of the invention is therefore to remedy the drawbacks of the aforementioned prior art by providing a titanium-based article, such as a piece of clothing for the watch industry, which is ductile while having a high hardness comparable to that of a hard metal, which does not contain any allergenic element, and which, when properly treated, has an aesthetic shine.
  • the invention also aims to provide a method of manufacturing by sintering such an article having a very low porosity.
  • Another object of the invention is to provide a method for hardening and coloring the surface of such an article in order to increase the hardness of the latter up to a level equivalent to that of a ceramic and to give it a good metallic appearance. ie having a high gloss.
  • the subject of the invention is an article based on titanium, characterized in that it is essentially composed of a mixture essentially comprising a titanium matrix and one or more addition elements chosen from the group comprising nitrides, carbides, carbonitrides, silicides, and the borides of the metallic elements of groups 3a, 4b, 5b, 6b, 7b, and 8b of the classification table of the elements, such as iron, titanium, silicon, niobium, molybdenum, chromium, tungsten , vanadium and aluminum or an alloy of metallic elements as well as aluminum oxide and zirconium oxide.
  • the article according to the invention advantageously has a high hardness which varies, depending on the choice of addition elements and their quantity in the mixture, typically between 300 and 1200 HV.
  • the article according to the invention is ductile and also has a high resistance to corrosion.
  • sintered titanium articles are obtained which have a porosity of less than 1% and which, after polishing, have a high gloss.
  • This process is thus particularly well suited to the production of decorative articles such as watch cases, bracelet links or the like.
  • the article is given a surface hardness of up to 3000HV. It is also possible, depending on the nature of the gas flow circulating around the article to be hardened, to color it and in particular to give it nuances of color close to those of gold.
  • Titanium hydride powder (TiH2), preferably having a high degree of purity (99.5%) and an average particle size of the order of a few microns, typically 10 microns, is conventionally mixed with a or several addition elements in the form of a powder of an inorganic material preferably having a high hardness and a particle size substantially equivalent to that of the titanium hydride powder or a mixture of powders of such inorganic materials.
  • These inorganic materials are chosen from the group comprising nitrides, carbides, carbonitrides, silicides and borides of the metallic elements of groups, 3a, 4b, 5b, 6b, 7b, and 8b of the classification table of the elements, such as iron, titanium, silicon, niobium, molybdenum, chromium, tungsten, vanadium and aluminum or an alloy of metallic elements as well as aluminum oxide and zirconium.
  • the titanium hydride powder typically represents 60 to 95% by weight of the mixture and preferably 80 to 90% by weight of the mixture.
  • the titanium hydride can be partially replaced, in a proportion not exceeding 50% by a hydride of an element from column 4b of the periodic table, such as zirconium hydride.
  • the proportion of titanium in the mixture makes it possible to influence the hardness of the article. A priori when the proportion of titanium in the mixture increases, the hardness of the article obtained from this mixture decreases. However, it has been found that by using a mixture of 80 to 90% of titanium hydride in conjunction with one of the addition elements such as those mentioned above or a combination of such elements, it was possible, against all expectations, an interesting compromise between the hardness, the machinability and the porosity of the articles produced from this mixture.
  • the mixture of titanium hydride powders and of the addition element or elements thus obtained is then stirred, in a conventional manner, with a temporary binder in the form of granules, until a homogeneous mixture in the form of a paste is obtained. .
  • the binder is formed from a thermal polymer or copolymer but can also be formed from wax.
  • This mixing is carried out at a temperature preferably between 120 ° and 180 ° C depending on the nature of the binder used.
  • the mixing temperature is of the order of 170 ° C.
  • the mixture in the form of a paste thus obtained is then injected into a mold having the shape of the part which it is desired to obtain, for example a watch case, with dimensions which take account of the withdrawal of the part during the subsequent stages. of the process, shrinkage which is typically of the order of 15%.
  • the injection is preferably carried out at a temperature typically around 140 ° C.
  • the shaped part is introduced into an oven in which it is gradually brought to a temperature preferably between 200 ° and 300 ° C. During this heating, the binder is gradually removed by evaporation. In order not to deteriorate the shape of the part, this heating is carried out in a time typically between 2 and 9 hours and, preferably, in 8 hours. It is also important that the elimination of the binder is complete to avoid any pollution of the part by the carbon and / or oxygen of the binder, which could lead to a deterioration of the mechanical properties of the part to be manufactured.
  • the removal of the binder is carried out under vacuum or in a hydrogen atmosphere in order, on the one hand, to avoid any oxidation of the binder during its removal, and, on the other hand, to increase the speed the process of removing the binder from the part without damaging its shape.
  • the binder is a thermal polymer
  • the latter can also be eliminated chemically, by decomposition using a vapor of an appropriate acid.
  • the atmosphere of the furnace is replaced by a hydrogen atmosphere (if the removal of the binder has not already been performed in a hydrogen atmosphere).
  • this hydrogen atmosphere is produced in the form of a flow circulating continuously in the furnace.
  • the temperature of the part is gradually increased until the desired sintering temperature is reached.
  • the sintering temperature is typically between 1,000 and 1,400 ° C and preferably substantially equal to 1,200 ° C to avoid getting too close to the temperature where the part would begin to deform.
  • This heating lasts approximately 2 to 8 hours.
  • the titanium hydride gradually releases its hydrogen.
  • the heating rate is between 150 ° C and 250 ° C per hour.
  • sintering can also be carried out in a vacuum or in an argon atmosphere.
  • the porosity of the articles obtained is of the order of 3% due to the violent release of the hydrogen from the titanium hydride at the time of heating which creates a large number of pores. These pores appear in particular on the surface of the article after polishing and scatter the incident light, which prevents perfect specular reflection of the light.
  • the use of such articles is therefore in this case limited to applications where the aesthetic appearance plays only a small role.
  • titanium since titanium has a high reactivity at high temperature, it reacts, during heating to the sintering temperature and subsequently during sintering, with the addition element or elements defined above to form new types of titanium compounds. Different types of reaction occur depending on the nature of the addition element (s) used. Four types of reaction have been noted.
  • the first type that has been noticed is a chemical displacement reaction such as: Ti + SiC ⁇ TiC + Ti x Si y (1)
  • a chemical displacement reaction such as: Ti + SiC ⁇ TiC + Ti x Si y (1)
  • the high reactivity of titanium is used at high temperature to dissociate chemically very stable materials and form new titanium compounds having a high hardness.
  • the second type of reaction which has been noticed is a reaction with the addition of titanium to form a sub-stoichiometric titanium compound such as: xTi + TiC ⁇ TiC (1-x) (2)
  • a sub-stoichiometric titanium compound such as: xTi + TiC ⁇ TiC (1-x) (2)
  • the third type of reaction which has been noticed is that forming an alloy of the intermetallic type such as: xTi + yW ⁇ Ti x W y (3) This type of reaction makes it possible in particular to obtain compounds having very high hardnesses.
  • the fourth type of reaction which has been noticed is that forming particles of hard materials, for example particles of tungsten carbides, embedded in a titanium matrix such as: xTi + WC ⁇ WC in a titanium matrix (4)
  • This latter type of reaction increases the hardness of the titanium article and leaves enough titanium on the surface to allow a chemical reaction with other elements during a subsequent surface treatment such as a coloring treatment and / or surface hardening.
  • the hardness of the article obtained according to this process depends in particular on the nature and the quantity of the compound or compounds which result from reactions (1) to (4) between the titanium and the element (s) of 'addition.
  • the atmosphere of the furnace that is to say the hydrogen
  • a non-reactive atmosphere such as an atmosphere of argon or helium, or vacuum.
  • Argon will be preferred.
  • the replacement of hydrogen by the non-reactive atmosphere or the vacuum is done while maintaining the article at its sintering temperature.
  • the duration of this replacement is typically between 5 and 80 minutes and is preferably about 20 minutes.
  • the part is then cooled to ambient temperature in said non-reactive atmosphere at a cooling rate of the order of 300 ° C per hour.
  • the sintered article obtained by the process which has just been described is composed of a mixture comprising a titanium matrix derived from titanium hydride and the element or elements of addition used during step (a ) described above.
  • This titanium-based article has a remarkably low porosity, typically from 2% to 0.1%.
  • this article has a hardness which can typically vary from 300 to 1200HV depending on the amount and type of addition element (s) added.
  • the article can then be subjected to a specular polishing of its surface in order to obtain a decorative article such as a watch case, a link bracelet, a dial or the like, having a surface of high polish and metallic shine.
  • the articles obtained by the process described above can be subjected to a hardening and coloring process.
  • This hardening and coloring process can be carried out before or after polishing the article. Also, for example for reasons of convenience, any polishing and / or machining operation of the article can be carried out before the implementation of this hardening and coloring process so that the article, in its form almost definitive or definitive, can be hardened and colored while retaining its shine and its shape.
  • the article is placed in an oven and heated to a temperature typically between 600 and 1000 ° C and preferably of the order of 800 ° C. Once this temperature has been reached, a flow of gas comprising carbon and / or nitrogen is circulated around the article to be treated for a period of the order of 10 to 30 minutes, the article being kept at temperature to which it was previously heated.
  • a hydrocarbon gas such as methane, propane, butane, etc. can be used.
  • the gas stream which comprises carbon and / or nitrogen is preferably diluted in an inert gas such as argon or helium.
  • the proportion of nitrogen in the gas flow is typically between 50 and 100% and preferably of the order of 95%.
  • the proportion of the gas containing carbon in the gas flow is typically between 2% and 20% and preferably of the order of 5%.
  • the depth to which the surface is cured depends on the temperature of the article and the reaction time of the article with carbon and / or nitrogen from the gas flow circulating around it.
  • this hardening and coloring process reinforces the corrosion resistance properties of the article. This reinforcement results from the properties of the elements formed in the surface layer which are similar to those of ceramics.
  • the increase in the hardness of the article depends on several factors and in particular on the reaction of the compound or compounds which result from reactions (1) to (4) with the gas flow which circulates in the oven.
  • TiCN titanium carbonitride powder
  • TiH2, 333 g titanium hydride
  • the cooled dough is granulated.
  • the granules obtained are then introduced into an injection press and injected into a mold, for example having the shape of a watch case, at a temperature of approximately 140 ° C.
  • the article conformed by this invention is then introduced into an oven in which a vacuum of approximately 10 ⁇ 2 millibar is then made.
  • the article is then brought to a temperature of about 200 ° C by linear heating in 8 hours.
  • the article is then sintered.
  • the vacuum of the oven is replaced by a hydrogen atmosphere in the form of a hydrogen flow having a flow rate of 250 ml / min, and the part is brought from 200 ° C to 1'200 ° C linearly. in 4 hours.
  • the hydrogen atmosphere is replaced by an argon atmosphere in the form of an argon flow. having a flow rate of 150 ml / min, and the temperature is maintained at 1200 ° C. for approximately 20 minutes.
  • the article is then cooled linearly under the same argon atmosphere to room temperature.
  • the cooling rate is 300 ° C. per hour and an article based on sintered titanium is thus obtained in which the titanium carbonitride has been combined with the titanium by a reaction of the type of reaction (2) above and whose porosity is less than 1%.
  • the hardness measured on the article is of the order of 780HV.
  • the sintered article is finally subjected to electropolishing to obtain a watch case having an intense metallic shine.
  • polyacetal is used as binder and the latter is removed by decomposition in a vapor of nitric acid at 120 ° C.
  • the result obtained with this variant is identical to that obtained with the previous example.
  • Example 2 the same steps were used as those described in Example 1 with 20% by volume of titanium carbonitride powder (TiCN, 102 g) and 80% by volume of hydride as starting material. titanium (TiH2, 296 g). There was thus obtained an article based on sintered titanium whose porosity is less than 1%. The hardness measured on this article is around 930HV. The article obtained has an intense metallic shine.
  • Example 2 the same steps were used as those described in Example 1 with 10% by volume of silicon carbide powder (SiC, 32 g) and 90% by volume of hydride as starting materials.
  • titanium TiH2, 333 g.
  • a titanium-based article was thus obtained sintered in which the silicon carbide has been dissociated according to a reaction similar to reaction (1) above to form titanium silicide.
  • the porosity of this article is less than 1%.
  • the hardness measured on this article is around 900HV.
  • the article obtained has an intense metallic shine.
  • Example 2 the same steps were used as those described in Example 1 with 20% by volume of silicon carbide powder (SiC, 64 g) and 80% by volume of hydride as starting materials. titanium (TiH2, 296 g). There was thus obtained an article based on sintered titanium whose porosity is less than 1%. The hardness measured on this article is around 1300HV. The article obtained has an intense metallic shine.
  • Example 2 the same steps were used as those described in Example 1 with 10% by volume of tungsten carbide powder (WC, 156 g) and 90% by volume of hydride as starting materials.
  • titanium TiH2, 333 g.
  • Example 2 the same steps were used as those described in Example 1, starting with 10% by volume of chromium carbide powder (Cr3C2, 67 g), 10% by volume of carbide powder of titanium (TiC, 49 g) and 80% by volume of titanium hydride (TiH2, 296 g). There was thus obtained an article based on sintered titanium whose porosity is less than 1%. The hardness measured on this article is around 920HV. The article obtained has an intense metallic shine.
  • Cr3C2, 67 g 10% by volume of carbide powder of titanium
  • TiH2 titanium hydride
  • Example 2 the same steps were used as those described in Example 1, starting with 10% by volume of chromium carbide powder (Cr3C2, 156 g), 10% by volume of carbide powder of titanium (TiC, 49 g) 50% by volume of titanium hydride (TiH2, 185 g) and 30% by volume of zirconium hydride (ZrH2, 168).
  • Cr3C2, 156 g 10% by volume of chromium carbide powder
  • TiC, 49 g 50% by volume of titanium hydride
  • ZrH2, 168 zirconium hydride
  • Example 2 the same steps were used as those described in Example 1 with 20% by volume of titanium carbide powder (TiC, 98 g), 50% by volume of hydride as starting materials. titanium (TiH2, 185 g) and 30% by volume of zirconium hydride (ZrH2, 168). There was thus obtained an article based on sintered titanium whose porosity is less than 1%. The hardness measured on this article is around 850HV. The article obtained has an intense metallic shine.
  • TiC titanium carbide powder
  • ZrH2, 168 zirconium hydride
  • the article is then gradually cooled to room temperature.
  • the nitrogen in the gas flow reacts with the sub-stoichiometric titanium carbonitride resulting from reaction (2) to give on the surface a compound comprising titanium carbonitride with a new sub- carbon and nitrogen stoichiometry.
  • Example 2b the same steps were used as those described in Example 1b, starting from an article based on sintered and polished titanium according to the method described above and which comprises 20% by volume as starting materials.
  • titanium carbide powder TiC, 98 g
  • 50% by volume of titanium hydride TiH2, 185 g
  • 30% by volume of zirconium hydride ZrH2, 168.
  • the article obtained after hardening and coloring has a golden yellow metallic appearance close to that of gold, and has a porosity less than 1%.
  • the hardness measured on this article is around 1800HV.
  • Example 2 the same steps were carried out as those described in Example 1b with an article based on polished titanium manufactured according to the method of the invention using as starting material 5% of titanium carbide (TiC , 25 g) and 95% titanium hydride (TiH2, 352 g).
  • TiC titanium carbide
  • TiH2, 352 g 95% titanium hydride
  • a gas flow comprising 2% of methane diluted in argon was used, the article being previously heated to 800 ° C.
  • the sub-stoichiometric titanium carbide which results from reaction (2) reacted with the carbon of the gas flow to form stoichiometric titanium carbide.
  • the hardness measured on this article is around 800HV and its metallic gloss is intense.

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Abstract

A novel Ti-based article consists of a mixt. of (a) a Ti matrix derived from titanium hydride and (b) one or more addn. elements selected from nitrides, carbides, carbonitrides, silicides and borides of gp. IIIa, IVb, Vb, VIb, VIIb and VIIIb elements (e.g. Fe, Ti, Si, Nb, Mo, Cr, W, V and Al) or their alloys, Al2O3 and ZrO2. Also claimed are (i) a process for mfg. the above article by sintering; and (ii) a method of hardening and colouring the surface of a Ti-based article made by the above process.

Description

L'invention concerne un article à base de titane, notamment un article décoratif tel qu'une pièce d'habillage pour l'horlogerie, ayant une dureté élevée et qui, une fois polie, présente une surface d'un brillant intense, ainsi qu'un procédé de fabrication d'un tel article, par frittage d'un mélange de poudre d'hydrure de titane (TiH₂) et d'éléments d'addition particuliers. L'invention concerne également un procédé de durcissement et de coloration d'une surface d'un tel article.The invention relates to an article based on titanium, in particular a decorative article such as a piece of clothing for the watch industry, having a high hardness and which, once polished, has a surface of intense gloss, as well as 'A method of manufacturing such an article, by sintering a mixture of titanium hydride powder (TiH₂) and specific addition elements. The invention also relates to a method for hardening and coloring a surface of such an article.

De manière générale, les pièces d'habillage pour l'horlogerie telles que les boîtes, les carrures, les maillons de bracelet, les cadrans de montre ou analogues, à dureté et à brillance élevées sont réalisées à partir d'aciers inoxydables austénitiques. Une des raisons principales de ce choix est que ce type d'acier peut être facilement embouti ou étampé.In general, the cladding parts for watchmaking, such as cases, middle parts, bracelet links, watch dials or the like, with high hardness and high gloss, are produced from austenitic stainless steels. One of the main reasons for this choice is that this type of steel can be easily stamped or stamped.

Toutefois, ces aciers contiennent généralement une quantité importante de nickel (environ 10%) ce qui constitue un inconvénient majeur pour la réalisation d'articles destinés à venir en contact avec la peau. En effet, le nickel tout comme le cobalt sont des constituants fortement allergènes susceptibles de contaminer la peau du porteur si bien que de nombreux pays ont mis sur pied des normes interdisant la vente d'articles en contact permanent avec la peau, susceptibles de telles contaminations, notamment par le nickel.However, these steels generally contain a large amount of nickel (approximately 10%), which constitutes a major drawback for the production of articles intended to come into contact with the skin. Indeed, nickel as well as cobalt are highly allergenic constituents capable of contaminating the wearer's skin, so that many countries have set up standards prohibiting the sale of articles in permanent contact with the skin, susceptible to such contamination. , especially by nickel.

Pour pallier cet inconvénient, les fabricants ont développé des boîtes de montre, des bracelets etc. qui utilisent des oxydes tels que l'oxyde d'aluminium et l'oxyde de zirconium. Ces oxydes répondent en effet aux problèmes de dureté et de contamination, mais présentent toutefois les inconvénients d'être très fragiles et d'avoir généralement un aspect éloigné de la brillance d'un métal et d'être coûteux à mettre en oeuvre.To overcome this drawback, manufacturers have developed watch cases, bracelets, etc. which use oxides such as aluminum oxide and zirconium oxide. These oxides do indeed respond to problems of hardness and contamination, but have however, the drawbacks of being very fragile and generally having an aspect far from the shine of a metal and of being costly to implement.

On connaît également des articles durs réalisés à base de carbure de titane ou de carbure de tungstène. Toutefois, bien que présentant une dureté élevée et un brillant métallique élevé, ces articles ne peuvent pas être frittés sans l'aide d'un liant si l'on veut qu'ils conservent une bonne ténacité. Or, les liants actuellement connus sont allergènes si bien que les articles ainsi obtenus sont aussi susceptibles de contaminer la peau des porteurs et donc soumis aux mêmes restrictions d'utilisation que les articles à base d'acier austénitique évoqués plus haut.Hard articles are also known which are made from titanium carbide or tungsten carbide. However, although having a high hardness and a high metallic gloss, these articles cannot be sintered without using a binder if they are to maintain good toughness. However, the currently known binders are allergenic so that the articles thus obtained are also likely to contaminate the skin of the carriers and therefore subject to the same restrictions of use as the articles based on austenitic steel mentioned above.

L'invention a donc pour but principal de remédier aux inconvénients de l'art antérieur susmentionné en fournissant un article à base de titane, tel qu'une pièce d'habillement pour l'horlogerie, ductile tout en présentant une dureté élevée comparable à celle d'un métal dur, qui ne contient aucun élément allergène, et qui, une fois traité de façon appropriée, présente une brillance esthétique.The main object of the invention is therefore to remedy the drawbacks of the aforementioned prior art by providing a titanium-based article, such as a piece of clothing for the watch industry, which is ductile while having a high hardness comparable to that of a hard metal, which does not contain any allergenic element, and which, when properly treated, has an aesthetic shine.

L'invention a également pour but de fournir un procédé de fabrication par frittage d'un tel article présentant une très faible porosité.The invention also aims to provide a method of manufacturing by sintering such an article having a very low porosity.

L'invention a encore pour but de fournir un procédé de durcissement et de coloration en surface d'un tel article pour augmenter la dureté de ce dernier jusqu'à un niveau équivalent à celle d'une céramique et lui donner un bon aspect métallique c'est-à-dire ayant un brillant élevé.Another object of the invention is to provide a method for hardening and coloring the surface of such an article in order to increase the hardness of the latter up to a level equivalent to that of a ceramic and to give it a good metallic appearance. ie having a high gloss.

A cet effet, l'invention a pour objet un article à base de titane, caractérisé en ce qu'il est composé essentiellement d'un mélange comprenant essentiellement une matrice de titane et un ou plusieurs éléments d'addition choisis parmi l'ensemble comprenant les nitrures, les carbures, les carbonitrures, les siliciures, et les borures des éléments métalliques des groupes 3a, 4b, 5b, 6b, 7b, et 8b de la table de classification des éléments, tel que le fer, le titane, le silicium, le niobium, le molybdène, le chrome, le tungstène, le vanadium et l'aluminium ou d'un alliage des éléments métalliques ainsi que l'oxyde d'aluminium et l'oxyde de zirconium.To this end, the subject of the invention is an article based on titanium, characterized in that it is essentially composed of a mixture essentially comprising a titanium matrix and one or more addition elements chosen from the group comprising nitrides, carbides, carbonitrides, silicides, and the borides of the metallic elements of groups 3a, 4b, 5b, 6b, 7b, and 8b of the classification table of the elements, such as iron, titanium, silicon, niobium, molybdenum, chromium, tungsten , vanadium and aluminum or an alloy of metallic elements as well as aluminum oxide and zirconium oxide.

L'article selon l'invention présente avantageusement une dureté élevée qui varie, en fonction du choix des éléments d'addition et de leur quantité dans le mélange, typiquement entre 300 et 1200 HV. L'article selon l'invention est ductile et présente en outre une grande résistance à la corrosion.The article according to the invention advantageously has a high hardness which varies, depending on the choice of addition elements and their quantity in the mixture, typically between 300 and 1200 HV. The article according to the invention is ductile and also has a high resistance to corrosion.

Selon un autre aspect, l'invention a également pour objet un procédé de fabrication par frittage d'un article à base de titane, caractérisé en ce qu'il consiste à:

  • (a) se munir d'un mélange d'une poudre d'hydrure de titane, d'une poudre d'un élément ou d'une combinaison de plusieurs éléments d'addition choisis parmi l'ensemble comprenant les nitrures, les carbures, les carbonitrures, les siliciures et les borures des éléments métalliques des groupes 3a, 4b, 5b, 6b, 7b, et 8b de la table de classification des éléments, tel que le fer, le titane, le silicium, le niobium, le molybdène, le chrome, le tungstène, le vanadium et l'aluminium ou d'un alliage des éléments métalliques ainsi que l'oxyde d'aluminium et l'oxyde de zirconium,
  • (b) injecter le mélange obtenu dans un moule pour obtenir un article de forme souhaitée,
  • (c) éliminer le liant,
  • (d) chauffer la pièce sous une atmosphère d'hydrogène jusqu'à la température de frittage désirée,
  • (e) remplacer l'atmosphère d'hydrogène par une atmosphère non réactive une fois que la température de frittage a été atteinte, et
  • (f) refroidir l'article dans l'atmosphère non réactive.
According to another aspect, the invention also relates to a process for manufacturing by sintering an article based on titanium, characterized in that it consists in:
  • (a) providing with a mixture of a titanium hydride powder, a powder of an element or a combination of several addition elements chosen from the group comprising nitrides, carbides, the carbonitrides, silicides and borides of the metallic elements of groups 3a, 4b, 5b, 6b, 7b, and 8b of the classification table of the elements, such as iron, titanium, silicon, niobium, molybdenum, chromium, tungsten, vanadium and aluminum or an alloy of metallic elements as well as aluminum oxide and zirconium oxide,
  • (b) injecting the mixture obtained into a mold to obtain an article of desired shape,
  • (c) removing the binder,
  • (d) heating the part under a hydrogen atmosphere to the desired sintering temperature,
  • (e) replacing the hydrogen atmosphere with a non-reactive atmosphere once the sintering temperature has been reached, and
  • (f) cooling the article in the non-reactive atmosphere.

Grâce à ce procédé, on obtient des articles en titane fritté qui présentent une porosité inférieure à 1% et qui, après polissage, présentent une brillance élevée. Ce procédé est ainsi particulièrement bien adapté à la réalisation d'articles décoratifs tels que des boîtes de montre, maillons de bracelets ou analogues.Thanks to this process, sintered titanium articles are obtained which have a porosity of less than 1% and which, after polishing, have a high gloss. This process is thus particularly well suited to the production of decorative articles such as watch cases, bracelet links or the like.

Selon encore un autre aspect, l'invention a également pour objet un procédé de durcissement et de coloration en surface d'un article à base de titane obtenu selon le procédé susdécrit, caractérisé en ce qu'il consiste à :

  • (g) placer l'article dans un four,
  • (h) chauffer l'article à une température déterminée et maintenir l'article à cette température pendant un temps déterminé, et
  • (i) faire circuler un flux de gaz comprenant du carbone et/ou de l'azote autour de l'article pour former, à la surface de l'article du carbure de titane, du nitrure de titane, du carbonitrure de titane ou un mélange de ces derniers.
According to yet another aspect, the subject of the invention is also a process for hardening and surface coloring of an article based on titanium obtained according to the above-described process, characterized in that it consists in:
  • (g) placing the article in an oven,
  • (h) heating the article to a determined temperature and maintaining the article at this temperature for a determined time, and
  • (i) circulating a gas stream comprising carbon and / or nitrogen around the article to form, on the surface of the article titanium carbide, titanium nitride, titanium carbonitride or a mixture of these.

Selon ce procédé, et grâce à la formation de ces nouveaux composés en surface, on confère à l'article une dureté superficielle pouvant atteindre 3000HV. On peut en outre, selon la nature du flux de gaz circulant autour de l'article à durcir, le colorer et notamment lui donner des nuances de couleur proches de celles de l'or.According to this process, and thanks to the formation of these new compounds on the surface, the article is given a surface hardness of up to 3000HV. It is also possible, depending on the nature of the gas flow circulating around the article to be hardened, to color it and in particular to give it nuances of color close to those of gold.

L'invention va maintenant être décrite de façon détaillée.The invention will now be described in detail.

De la poudre d'hydrure de titane (TiH₂), présentant de préférence un grand degré de pureté (99,5%) et une granulométrie moyenne de l'ordre de quelques microns, typiquement de 10 microns, est mélangée de façon classique avec un ou plusieurs éléments d'addition sous la forme d'une poudre d'un matériau inorganique ayant, de préférence, une dureté élevée et une granulométrie sensiblement équivalente à celle de la poudre d'hydrure de titane ou d'un mélange de poudres de tels matériaux inorganiques.Titanium hydride powder (TiH₂), preferably having a high degree of purity (99.5%) and an average particle size of the order of a few microns, typically 10 microns, is conventionally mixed with a or several addition elements in the form of a powder of an inorganic material preferably having a high hardness and a particle size substantially equivalent to that of the titanium hydride powder or a mixture of powders of such inorganic materials.

Ces matériaux inorganiques sont choisis parmi l'ensemble comprenant les nitrures, les carbures, les carbonitrures, les siliciures et les borures des éléments métalliques des groupes, 3a, 4b, 5b, 6b, 7b, et 8b de la table de classification des éléments, tel que le fer, le titane, le silicium, le niobium, le molybdène, le chrome, le tungstène, le vanadium et l'aluminium ou d'un alliage des éléments métalliques ainsi que l'oxyde d'aluminium et l'oxyde de zirconium.These inorganic materials are chosen from the group comprising nitrides, carbides, carbonitrides, silicides and borides of the metallic elements of groups, 3a, 4b, 5b, 6b, 7b, and 8b of the classification table of the elements, such as iron, titanium, silicon, niobium, molybdenum, chromium, tungsten, vanadium and aluminum or an alloy of metallic elements as well as aluminum oxide and zirconium.

La poudre d'hydrure de titane représente typiquement 60 à 95% en poids du mélange et de préférence 80 à 90% en poids du mélange.The titanium hydride powder typically represents 60 to 95% by weight of the mixture and preferably 80 to 90% by weight of the mixture.

Selon une variante de réalisation l'hydrure de titane peut partiellement être remplacé, dans une proportion n'excédant pas 50% par un hydrure d'un élément de la colonne 4b de la classification périodique, tel que l'hydrure de zirconium.According to an alternative embodiment, the titanium hydride can be partially replaced, in a proportion not exceeding 50% by a hydride of an element from column 4b of the periodic table, such as zirconium hydride.

La proportion de titane dans le mélange permet d'influencer la dureté de l'article. A priori lorsque la proportion de titane dans le mélange augmente, la dureté de l'article obtenu à partir de ce mélange diminue. Toutefois, on s'est aperçu qu'en utilisant un mélange de 80 à 90% d'hydrure de titane en liaison avec un des éléments d'addition tels que ceux mentionnés plus haut ou une combinaison de tels éléments, on pouvait atteindre, contre toute attente, un compromis intéressant entre la dureté, l'usinabilité et la porosité des articles réalisés à partir de ce mélange.The proportion of titanium in the mixture makes it possible to influence the hardness of the article. A priori when the proportion of titanium in the mixture increases, the hardness of the article obtained from this mixture decreases. However, it has been found that by using a mixture of 80 to 90% of titanium hydride in conjunction with one of the addition elements such as those mentioned above or a combination of such elements, it was possible, against all expectations, an interesting compromise between the hardness, the machinability and the porosity of the articles produced from this mixture.

Le mélange des poudres d'hydrure de titane et du ou des éléments d'addition ainsi obtenu est alors brassé, de façon classique, avec un liant temporaire ayant la forme de granules, jusqu'à obtenir un mélange homogène sous forme d'une pâte.The mixture of titanium hydride powders and of the addition element or elements thus obtained is then stirred, in a conventional manner, with a temporary binder in the form of granules, until a homogeneous mixture in the form of a paste is obtained. .

De préférence, le liant est formé d'un polymère ou d'un copolymère thermique mais peut être également formé de cire. Ce mélange est réalisé à une température comprise de préférence entre 120° et 180°C selon la nature du liant utilisé. Typiquement, avec un copolymère thermique, la température de mélange est de l'ordre de 170°C.Preferably, the binder is formed from a thermal polymer or copolymer but can also be formed from wax. This mixing is carried out at a temperature preferably between 120 ° and 180 ° C depending on the nature of the binder used. Typically, with a thermal copolymer, the mixing temperature is of the order of 170 ° C.

Le mélange sous forme de pâte ainsi obtenu est ensuite injecté dans un moule ayant la forme de la pièce que l'on désire obtenir, par exemple une boîte de montre, avec des dimensions qui tiennent compte du retrait de la pièce au cours des étapes ultérieures du procédé, rétrécissement qui est typiquement de l'ordre de 15%. L'injection est réalisée de préférence à une température typiquement d'environ 140°C.The mixture in the form of a paste thus obtained is then injected into a mold having the shape of the part which it is desired to obtain, for example a watch case, with dimensions which take account of the withdrawal of the part during the subsequent stages. of the process, shrinkage which is typically of the order of 15%. The injection is preferably carried out at a temperature typically around 140 ° C.

On procède ensuite à l'élimination du liant contenu dans la pièce conformée. Cette élimination du liant est réalisée thermiquement. Pour ce faire, la pièce conformée est introduite dans un four dans lequel elle est amenée progressivement à une température comprise de préférence entre 200° et 300°C. Au cours de ce chauffage, le liant est progressivement éliminé par évaporation. Pour ne pas détériorer la forme de la pièce, ce chauffage s'effectue en un temps compris typiquement entre 2 et 9 heures et, de préférence, en 8 heures. Il est également important que l'élimination du liant soit complète pour éviter toute pollution de la pièce par le carbone et/ou l'oxygène du liant, qui pourrait conduire à une détérioration des propriétés mécaniques de la pièce à fabriquer.We then proceed to the elimination of the binder contained in the shaped part. This elimination of the binder is carried out thermally. To do this, the shaped part is introduced into an oven in which it is gradually brought to a temperature preferably between 200 ° and 300 ° C. During this heating, the binder is gradually removed by evaporation. In order not to deteriorate the shape of the part, this heating is carried out in a time typically between 2 and 9 hours and, preferably, in 8 hours. It is also important that the elimination of the binder is complete to avoid any pollution of the part by the carbon and / or oxygen of the binder, which could lead to a deterioration of the mechanical properties of the part to be manufactured.

De préférence, l'élimination du liant est réalisée sous vide ou dans une atmosphère d'hydrogène afin, d'une part, d'éviter toute oxydation du liant lors de son élimination, et, d'autre part, d'augmenter la vitesse du processus d'élimination du liant de la pièce sans en détériorer la forme.Preferably, the removal of the binder is carried out under vacuum or in a hydrogen atmosphere in order, on the one hand, to avoid any oxidation of the binder during its removal, and, on the other hand, to increase the speed the process of removing the binder from the part without damaging its shape.

Selon une variante du procédé et notamment dans le cas où le liant est un polymère thermique, ce dernier peut être également éliminé de façon chimique, par décomposition à l'aide d'une vapeur d'un acide approprié.According to a variant of the process and in particular in the case where the binder is a thermal polymer, the latter can also be eliminated chemically, by decomposition using a vapor of an appropriate acid.

Après l'élimination complète du liant de la pièce, l'atmosphère du four est remplacée par une atmosphère d'hydrogène (si l'élimination du liant n'a pas déjà été réalisée dans une atmosphère d'hydrogène). De préférence, cette atmosphère d'hydrogène est réalisée sous la forme d'un flux circulant de façon continue dans le four. Simultanément, la température de la pièce est progressivement augmentée jusqu'à atteindre la température de frittage désirée. La température de frittage est comprise typiquement entre 1'000 et 1'400°C et, de préférence, sensiblement égale à 1'200°C pour éviter de se rapprocher trop de la température où la pièce commencerait à se déformer.After the complete removal of the binder from the part, the atmosphere of the furnace is replaced by a hydrogen atmosphere (if the removal of the binder has not already been performed in a hydrogen atmosphere). Preferably, this hydrogen atmosphere is produced in the form of a flow circulating continuously in the furnace. At the same time, the temperature of the part is gradually increased until the desired sintering temperature is reached. The sintering temperature is typically between 1,000 and 1,400 ° C and preferably substantially equal to 1,200 ° C to avoid getting too close to the temperature where the part would begin to deform.

Ce chauffage dure environ 2 à 8 heures. Au cours du chauffage, l'hydrure de titane libère progressivement son hydrogène. A ce propos il est important (selon le procédé de l'invention) que le chauffage ne soit pas trop rapide afin de ne pas provoquer une libération rapide de l'hydrogène qui pourrait provoquer la formation de pores au sein de la pièce et par là même altérer le brillant de la surface de l'article après le polissage de celui-ci. De préférence, la vitesse de chauffage est comprise entre 150°C et 250°C par heure.This heating lasts approximately 2 to 8 hours. During heating, the titanium hydride gradually releases its hydrogen. In this regard it is important (according to the method of the invention) that the heating is not too rapid so as not to cause a rapid release of the hydrogen which could cause the formation of pores within the room and thereby even alter the shine of the article's surface after polishing it. Preferably, the heating rate is between 150 ° C and 250 ° C per hour.

Selon une variante du procédé, on peut aussi réaliser le frittage dans le vide ou dans une atmosphère d'argon. Toutefois, dans un tel cas la porosité des articles obtenus est de l'ordre de 3% en raison de la libération violente de l'hydrogène à partir de l'hydrure de titane au moment du chauffage qui crée un nombre important de pores. Ces pores apparaissent notamment à la surface de l'article après son polissage et diffusent la lumière incidente, ce qui empêche une réflexion spéculaire parfaite de la lumière. L'utilisation de tels articles est donc dans ce cas limitée à des applications où l'aspect esthétique ne joue qu'un faible rôle.According to a variant of the process, sintering can also be carried out in a vacuum or in an argon atmosphere. However, in such a case, the porosity of the articles obtained is of the order of 3% due to the violent release of the hydrogen from the titanium hydride at the time of heating which creates a large number of pores. These pores appear in particular on the surface of the article after polishing and scatter the incident light, which prevents perfect specular reflection of the light. The use of such articles is therefore in this case limited to applications where the aesthetic appearance plays only a small role.

Par ailleurs, le titane ayant une grande réactivité à température élevée, il réagit, au cours du chauffage jusqu'à la température de frittage et par la suite au cours du frittage, avec le ou les éléments d'addition définis plus haut pour former de nouveaux types de composés de titane. Il se produit différents types de réaction selon la nature du ou des éléments d'addition utilisés. Quatre types de réaction ont été remarqués.Furthermore, since titanium has a high reactivity at high temperature, it reacts, during heating to the sintering temperature and subsequently during sintering, with the addition element or elements defined above to form new types of titanium compounds. Different types of reaction occur depending on the nature of the addition element (s) used. Four types of reaction have been noted.

Le premier type qui a été remarqué est une réaction à déplacement chimique telle que :



        Ti + SiC → TiC + TixSiy   (1)



   On utilise ainsi avantageusement la réactivité élevée du titane à haute température pour dissocier des matériaux chimiquement très stables et former de nouveaux composés de titane ayant une dureté élevée.The first type that has been noticed is a chemical displacement reaction such as:



Ti + SiC → TiC + Ti x Si y (1)



Advantageously, the high reactivity of titanium is used at high temperature to dissociate chemically very stable materials and form new titanium compounds having a high hardness.

Le deuxième type de réaction qui a été remarqué est une réaction à addition de titane pour former un composé de titane sous-stoechiométrique telle que :



        xTi + TiC → TiC(1-x)   (2)



   Avec ce type de réaction, la stoechiométrie du nouveau composé de titane peut être modifiée dans une grande plage et ainsi la dureté de l'article peut être adaptée.The second type of reaction which has been noticed is a reaction with the addition of titanium to form a sub-stoichiometric titanium compound such as:



xTi + TiC → TiC (1-x) (2)



With this type of reaction, the stoichiometry of the new titanium compound can be changed over a wide range and thus the hardness of the article can be adjusted.

Le troisième type de réaction qui a été remarqué est celle formant un alliage du type intermétallique telle que :



        xTi + yW → TixWy   (3)



   Ce type de réaction permet notamment d'obtenir des composés ayant des duretés très élevée.The third type of reaction which has been noticed is that forming an alloy of the intermetallic type such as:



xTi + yW → Ti x W y (3)



This type of reaction makes it possible in particular to obtain compounds having very high hardnesses.

Enfin, le quatrième type de réaction qui a été remarqué est celle formant des particules de matériaux durs, par exemple des particules de carbures de tungstène, noyées dans une matrice de titane telle que :



        xTi + WC → WC dans une matrice de titane   (4)



   Ce dernier type de réaction augmente la dureté de l'article en titane et laisse suffisamment de titane en surface pour permettre une réaction chimique avec d'autres éléments au cours d'un traitement de surface ultérieur tel qu'un traitement de coloration et/ou de durcissement en surface.Finally, the fourth type of reaction which has been noticed is that forming particles of hard materials, for example particles of tungsten carbides, embedded in a titanium matrix such as:



xTi + WC → WC in a titanium matrix (4)



This latter type of reaction increases the hardness of the titanium article and leaves enough titanium on the surface to allow a chemical reaction with other elements during a subsequent surface treatment such as a coloring treatment and / or surface hardening.

A ce propos, on rappelera que la dureté de l'article obtenu selon ce procédé dépend notamment de la nature et de la quantité du ou des composés qui résultent des réactions (1) à (4) entre le titane et le ou les éléments d'addition.In this regard, it will be recalled that the hardness of the article obtained according to this process depends in particular on the nature and the quantity of the compound or compounds which result from reactions (1) to (4) between the titanium and the element (s) of 'addition.

La température de frittage atteinte et l'hydrogène de la pièce ayant été en majeure partie libéré, on remplace à nouveau l'atmosphère du four, c'est à dire l'hydrogène, par une atmosphère non réactive telle qu'une atmosphère d'argon ou d'hélium, ou du vide. L'argon sera préféré. Le remplacement de l'hydrogène par l'atmosphère non réactive ou le vide est fait tout en maintenant l'article à sa température de frittage. La durée de ce remplacement est comprise typiquement entre 5 et 80 minutes et elle est de préférence d'environ 20 minutes.Once the sintering temperature has been reached and the hydrogen in the part has been released for the most part, the atmosphere of the furnace, that is to say the hydrogen, is again replaced by a non-reactive atmosphere such as an atmosphere of argon or helium, or vacuum. Argon will be preferred. The replacement of hydrogen by the non-reactive atmosphere or the vacuum is done while maintaining the article at its sintering temperature. The duration of this replacement is typically between 5 and 80 minutes and is preferably about 20 minutes.

La pièce est alors refroidie jusqu'à la température ambiante dans ladite atmosphère non réactive à une vitesse de refroidissement de l'ordre de 300°C par heure.The part is then cooled to ambient temperature in said non-reactive atmosphere at a cooling rate of the order of 300 ° C per hour.

L'article fritté obtenu par le procédé qui vient d'être décrit est composé d'un mélange comprenant une matrice de titane dérivée de l'hydrure de titane et l'élément ou les éléments d'addition utilisés lors de l'étape (a) décrite ci-dessus.The sintered article obtained by the process which has just been described is composed of a mixture comprising a titanium matrix derived from titanium hydride and the element or elements of addition used during step (a ) described above.

Cet article à base de titane présente une porosité remarquablement faible, typiquement de 2% à 0,1%.This titanium-based article has a remarkably low porosity, typically from 2% to 0.1%.

En outre, cet article présente une dureté qui peut varier typiquement de 300 à 1200HV en fonction de la quantité et du type de ou des éléments d'addition ajoutés.In addition, this article has a hardness which can typically vary from 300 to 1200HV depending on the amount and type of addition element (s) added.

L'article peut être soumis ensuite à un polissage spéculaire de sa surface afin d'obtenir un article décoratif tel qu'une boîte de montre, un maillon de bracelet, un cadran ou analogue, présentant une surface d'un poli et d'un brillant métallique élevé.The article can then be subjected to a specular polishing of its surface in order to obtain a decorative article such as a watch case, a link bracelet, a dial or the like, having a surface of high polish and metallic shine.

Comme cela a été mentionné plus haut, les articles obtenus par le procédé décrit ci-dessus peuvent être, selon un autre aspect de l'invention, soumis à un procédé de durcissement et de coloration.As mentioned above, according to another aspect of the invention, the articles obtained by the process described above can be subjected to a hardening and coloring process.

Ce procédé de durcissement et de coloration peut être mis en oeuvre avant ou après le polissage de l'article. Aussi, par exemple pour des raisons de commodité, on peut effectuer toute opération de polissage et/ou d'usinage de l'article avant la mise en oeuvre de ce procédé de durcissement et de coloration si bien que l'article, dans sa forme quasi définitive ou définitive, pourra être durci et coloré tout en conservant sa brillance et sa forme.This hardening and coloring process can be carried out before or after polishing the article. Also, for example for reasons of convenience, any polishing and / or machining operation of the article can be carried out before the implementation of this hardening and coloring process so that the article, in its form almost definitive or definitive, can be hardened and colored while retaining its shine and its shape.

Pour procéder au durcissement et à la coloration de l'article, le cas échéant déjà usiné dans sa forme définitive et/ou poli, on place l'article dans un four et on le chauffe jusqu'à une température comprise typiquement entre 600 et 1000°C et de préférence de l'ordre de 800°C. Une fois cette température atteinte, on fait circuler autour de l'article à traiter un flux de gaz comprenant du carbone et/ou de l'azote pendant une durée de l'ordre de 10 à 30 minutes, l'article étant maintenu à la température à laquelle il a été préalablement chauffé.To harden and color the article, possibly already machined in its final and / or polished form, the article is placed in an oven and heated to a temperature typically between 600 and 1000 ° C and preferably of the order of 800 ° C. Once this temperature has been reached, a flow of gas comprising carbon and / or nitrogen is circulated around the article to be treated for a period of the order of 10 to 30 minutes, the article being kept at temperature to which it was previously heated.

Comme gaz contenant du carbone, on peut utiliser un gaz hydrocarbure tel que le méthane, le propane, le butane etc.As the carbon-containing gas, a hydrocarbon gas such as methane, propane, butane, etc. can be used.

Lorsque de l'azote est utilisé, on veillera à ce qu'il soit aussi pur que possible et ne contienne notamment que des quantités d'eau et d'oxygène minimum.When nitrogen is used, care should be taken to ensure that it is as pure as possible and in particular contains only minimum quantities of water and oxygen.

Pour obtenir un résultat satisfaisant, le flux de gaz qui comprend du carbone et/ou de l'azote est de préférence dilué dans un gaz inerte tel que l'argon ou l'hélium.To obtain a satisfactory result, the gas stream which comprises carbon and / or nitrogen is preferably diluted in an inert gas such as argon or helium.

Le cas échéant, la proportion d'azote dans le flux de gaz est comprise typiquement entre 50 et 100% et de préférence de l'ordre de 95%.Where appropriate, the proportion of nitrogen in the gas flow is typically between 50 and 100% and preferably of the order of 95%.

De même, la proportion du gaz contenant du carbone dans le flux de gaz est comprise typiquement entre 2% et 20% et de préférence de l'ordre de 5%.Likewise, the proportion of the gas containing carbon in the gas flow is typically between 2% and 20% and preferably of the order of 5%.

Dans le cas d'un mélange d'azote et d'un gaz contenant du carbone, les proportions susmentionnées pour chacun des gaz doivent être respectées.In the case of a mixture of nitrogen and a carbon-containing gas, the above-mentioned proportions for each of the gases must be respected.

La profondeur sur laquelle la surface est durcie dépend de la température de l'article et du temps de réaction de l'article avec le carbone et/ou l'azote du flux de gaz circulant autour de ce dernier.The depth to which the surface is cured depends on the temperature of the article and the reaction time of the article with carbon and / or nitrogen from the gas flow circulating around it.

On notera toutefois que dans le cas où l'article a été préalablement poli, on chauffera ce dernier à une température telle que les réactions de formation de carbures, de nitrures et de carbonitrures soient suffisamment lentes pour obtenir une surface dure et qui conserve son aspect poli.It will be noted however that in the case where the article has been previously polished, the latter will be heated to a temperature such that the reactions for the formation of carbides, nitrides and carbonitrides are sufficiently slow to obtain a hard surface which retains its appearance polished.

En utilisant un flux de gaz ne contenant que du carbone, on obtient un article ayant un aspect métallique.By using a gas stream containing only carbon, an article having a metallic appearance is obtained.

En revanche, si on utilise un flux de gaz ne contenant que de l'azote, on obtient un article ayant un aspect coloré.On the other hand, if a gas flow containing only nitrogen is used, an article having a colored appearance is obtained.

En utilisant un mélange de carbone et d'azote dans le flux de gaz, on peut obtenir, en faisant varier leur proportions respectives, toutes les nuances de couleurs entre le jaune et le brun et notamment la couleur or.By using a mixture of carbon and nitrogen in the gas flow, one can obtain, by varying their respective proportions, all the nuances of colors between yellow and brown and in particular the color gold.

On notera en outre que ce procédé de durcissement et de coloration renforce les propriétés de résistance à la corrosion de l'article. Ce renforcement résulte des propriétés des éléments formés dans la couche superficielle qui sont analogues à celles des céramiques.It will further be noted that this hardening and coloring process reinforces the corrosion resistance properties of the article. This reinforcement results from the properties of the elements formed in the surface layer which are similar to those of ceramics.

L'augmentation de la dureté de l'article dépend de plusieurs facteurs et notamment de la réaction du ou des composés qui résultent des réactions (1) à (4) avec le flux de gaz qui circule dans le four.The increase in the hardness of the article depends on several factors and in particular on the reaction of the compound or compounds which result from reactions (1) to (4) with the gas flow which circulates in the oven.

On décrira ci-dessous quelques exemples de mise en oeuvre du procédé de fabrication par frittage d'un article à base de titane selon l'invention. Par commodité pour la préparation des mélanges, les quantités respectives des composants ont été exprimées par des pourcentages en volume, les poids indiqués entre parenthèses permettant sans équivoque de les convertir en des pourcentages en poids.A few examples of the implementation of the sintering process for manufacturing a titanium-based article according to the invention will be described below. For convenience preparation of the mixtures, the respective quantities of the components were expressed as percentages by volume, the weights indicated in parentheses making it possible unequivocally to convert them into percentages by weight.

Exemple 1Example 1

On verse, dans un mélangeur classique contenant un solvant, par exemple du cyclohexane, 10% en volume de poudre de carbonitrure de titane (TiCN, 51 g) et 90% en volume d'hydrure de titane (TiH₂, 333 g).10% by volume of titanium carbonitride powder (TiCN, 51 g) and 90% by volume of titanium hydride (TiH₂, 333 g) are poured into a conventional mixer containing a solvent, for example cyclohexane.

On mélange ces éléments pendant environ 30 minutes à température ambiante. Le mélange homogène ainsi obtenu est alors séché puis versé dans un récipient contenant un liant formé d'un copolymère comprenant 32% en volume d'oxyde de polyéthylène (246 g) et 4% en volume de polypropylène (26 g). On chauffe ce liant et ce mélange à une température d'environ 170°C jusqu'à obtenir une pâte homogène.These elements are mixed for about 30 minutes at room temperature. The homogeneous mixture thus obtained is then dried and then poured into a container containing a binder formed of a copolymer comprising 32% by volume of polyethylene oxide (246 g) and 4% by volume of polypropylene (26 g). This binder and this mixture are heated to a temperature of approximately 170 ° C. until a homogeneous paste is obtained.

On procède ensuite à une granulation de la pâte refroidie. Les granules obtenus sont alors introduits dans une presse à injecter et injectés dans un moule, ayant par exemple la forme d'une boîte de montre, à une température d'environ 140°C.Next, the cooled dough is granulated. The granules obtained are then introduced into an injection press and injected into a mold, for example having the shape of a watch case, at a temperature of approximately 140 ° C.

L'article conformé par cette invention est alors introduit dans un four dans lequel on fait ensuite un vide d'environ 10⁻² millibar. L'article est ensuite amené à une température d'environ 200°C par un chauffage linéaire en 8 heures.The article conformed by this invention is then introduced into an oven in which a vacuum of approximately 10⁻² millibar is then made. The article is then brought to a temperature of about 200 ° C by linear heating in 8 hours.

On opère ensuite le frittage de l'article. Pour ce faire, le vide du four est remplacé par une atmosphère d'hydrogène sous forme d'un flux d'hydrogène ayant un débit de 250 ml/min, et la pièce est amenée de 200°C à 1'200°C linéairement en 4 heures. Une fois la température de 1'200°C atteinte, on remplace l'atmosphère d'hydrogène par une atmosphère d'argon sous forme d'un flux d'argon ayant un débit de 150 ml/min, et on maintient la température de 1'200°C pendant environ 20 minutes.The article is then sintered. To do this, the vacuum of the oven is replaced by a hydrogen atmosphere in the form of a hydrogen flow having a flow rate of 250 ml / min, and the part is brought from 200 ° C to 1'200 ° C linearly. in 4 hours. Once the temperature of 1,200 ° C is reached, the hydrogen atmosphere is replaced by an argon atmosphere in the form of an argon flow. having a flow rate of 150 ml / min, and the temperature is maintained at 1200 ° C. for approximately 20 minutes.

On refroidit ensuite linéairement l'article sous la même atmosphère d'argon jusqu'à la température ambiante. La vitesse de refroidissement est de 300°C par heure et on obtient ainsi un article à base de titane fritté dans lequel le carbonitrure de titane a été combiné au titane par une réaction du type de la réaction (2) ci-dessus et dont la porosité est inférieure à 1%. La dureté mesurée sur l'article est de l'ordre de 780HV.The article is then cooled linearly under the same argon atmosphere to room temperature. The cooling rate is 300 ° C. per hour and an article based on sintered titanium is thus obtained in which the titanium carbonitride has been combined with the titanium by a reaction of the type of reaction (2) above and whose porosity is less than 1%. The hardness measured on the article is of the order of 780HV.

L'article fritté est finalement soumis à un électropolissage pour obtenir une boîte de montre ayant un brillant métallique intense.The sintered article is finally subjected to electropolishing to obtain a watch case having an intense metallic shine.

Dans une variante de l'exemple ci-dessus, on utilise du polyacétal comme liant et ce dernier est éliminé par décomposition dans une vapeur d'acide nitrique à 120°C. Le résultat obtenu avec cette variante est identique à celui obtenu avec l'exemple précédent.In a variant of the above example, polyacetal is used as binder and the latter is removed by decomposition in a vapor of nitric acid at 120 ° C. The result obtained with this variant is identical to that obtained with the previous example.

Exemple 1aExample 1a

Dans cet exemple, on a mis en oeuvre les mêmes étapes que celles décrites dans l'exemple 1 avec comme produit de départ 20% en volume de poudre de carbonitrure de titane (TiCN, 102 g) et 80% en volume d'hydrure de titane (TiH₂, 296 g). On a obtenu ainsi un article à base de titane fritté dont la porosité est inférieure à 1%. La dureté mesurée sur cet article est de l'ordre de 930HV. L'article obtenu présente un brillant métallique intense.In this example, the same steps were used as those described in Example 1 with 20% by volume of titanium carbonitride powder (TiCN, 102 g) and 80% by volume of hydride as starting material. titanium (TiH₂, 296 g). There was thus obtained an article based on sintered titanium whose porosity is less than 1%. The hardness measured on this article is around 930HV. The article obtained has an intense metallic shine.

Exemple 2Example 2

Dans cet exemple, on a mis en oeuvre les mêmes étapes que celles décrites dans l'exemple 1 avec comme produits de départ 10% en volume de poudre de carbure de silicium (SiC, 32 g) et 90% en volume d'hydrure de titane (TiH₂, 333 g). On a obtenu ainsi un article à base de titane fritté dans lequel le carbure de silicium a été dissocié selon une réaction semblable à la réaction (1) ci-dessus pour former du siliciure de titane. La porosité de cet article est inférieure à 1%. La dureté mesurée sur cet article est de l'ordre de 900HV. L'article obtenu présente un brillant métallique intense.In this example, the same steps were used as those described in Example 1 with 10% by volume of silicon carbide powder (SiC, 32 g) and 90% by volume of hydride as starting materials. titanium (TiH₂, 333 g). A titanium-based article was thus obtained sintered in which the silicon carbide has been dissociated according to a reaction similar to reaction (1) above to form titanium silicide. The porosity of this article is less than 1%. The hardness measured on this article is around 900HV. The article obtained has an intense metallic shine.

Exemple 2aExample 2a

Dans cet exemple, on a mis en oeuvre les mêmes étapes que celles décrites dans l'exemple 1 avec comme produits de départ 20% en volume de poudre de carbure de silicium (SiC, 64 g) et 80% en volume d'hydrure de titane (TiH₂, 296 g). On a obtenu ainsi un article à base de titane fritté dont la porosité est inférieure à 1%. La dureté mesurée sur cet article est de l'ordre de 1300HV. L'article obtenu présente un brillant métallique intense.In this example, the same steps were used as those described in Example 1 with 20% by volume of silicon carbide powder (SiC, 64 g) and 80% by volume of hydride as starting materials. titanium (TiH₂, 296 g). There was thus obtained an article based on sintered titanium whose porosity is less than 1%. The hardness measured on this article is around 1300HV. The article obtained has an intense metallic shine.

Exemple 3Example 3

Dans cet exemple, on a mis en oeuvre les mêmes étapes que celles décrites dans l'exemple 1 avec comme produits de départ 10% en volume de poudre de carbure de tungstène (WC, 156 g) et 90% en volume d'hydrure de titane (TiH₂, 333 g). On a obtenu ainsi un article à base de titane fritté dans lequel le carbure de tungstène est noyé dans une matrice de titane et dont la porosité est inférieure à 1%. La dureté mesurée sur cet article est de l'ordre de 630HV. L'article obtenu présente un brillant métallique intense.In this example, the same steps were used as those described in Example 1 with 10% by volume of tungsten carbide powder (WC, 156 g) and 90% by volume of hydride as starting materials. titanium (TiH₂, 333 g). There was thus obtained an article based on sintered titanium in which the tungsten carbide is embedded in a titanium matrix and whose porosity is less than 1%. The hardness measured on this article is around 630HV. The article obtained has an intense metallic shine.

Exemple 4Example 4

Dans cet exemple, on a mis en oeuvre les mêmes étapes que celles décrites dans l'exemple 1 avec comme produits de départ 10% en volume de poudre de carbure de chrome (Cr₃C₂, 67 g), 10% en volume de poudre de carbure de titane (TiC, 49 g) et 80% en volume d'hydrure de titane (TiH₂, 296 g). On a obtenu ainsi un article à base de titane fritté dont la porosité est inférieure à 1%. La dureté mesurée sur cet article est de l'ordre de 920HV. L'article obtenu présente un brillant métallique intense.In this example, the same steps were used as those described in Example 1, starting with 10% by volume of chromium carbide powder (Cr₃C₂, 67 g), 10% by volume of carbide powder of titanium (TiC, 49 g) and 80% by volume of titanium hydride (TiH₂, 296 g). There was thus obtained an article based on sintered titanium whose porosity is less than 1%. The hardness measured on this article is around 920HV. The article obtained has an intense metallic shine.

Exemple 5Example 5

Dans cet exemple, on a mis en oeuvre les mêmes étapes que celles décrites dans l'exemple 1 avec comme produits de départ 10% en volume de poudre de carbure de chrome (Cr₃C₂, 156 g), 10% en volume de poudre de carbure de titane (TiC, 49 g) 50% en volume d'hydrure de titane (TiH₂, 185 g) et 30% en volume d'hydrure de zirconium (ZrH₂, 168). On a obtenu ainsi un article à base de titane fritté dont la porosité est inférieure à 1%. La dureté mesurée sur cet article est de l'ordre de 770HV. L'article obtenu présente un brillant métallique intense.In this example, the same steps were used as those described in Example 1, starting with 10% by volume of chromium carbide powder (Cr₃C₂, 156 g), 10% by volume of carbide powder of titanium (TiC, 49 g) 50% by volume of titanium hydride (TiH₂, 185 g) and 30% by volume of zirconium hydride (ZrH₂, 168). There was thus obtained an article based on sintered titanium whose porosity is less than 1%. The hardness measured on this article is around 770HV. The article obtained has an intense metallic shine.

Exemple 6Example 6

Dans cet exemple, on a mis en oeuvre les mêmes étapes que celles décrites dans l'exemple 1 avec comme produits de départ 20% en volume de poudre de carbure de titane (TiC, 98 g), 50% en volume d'hydrure de titane (TiH₂, 185 g) et 30% en volume d'hydrure de zirconium (ZrH₂, 168). On a obtenu ainsi un article à base de titane fritté dont la porosité est inférieure à 1%. La dureté mesurée sur cet article est de l'ordre de 850HV. L'article obtenu présente un brillant métallique intense.In this example, the same steps were used as those described in Example 1 with 20% by volume of titanium carbide powder (TiC, 98 g), 50% by volume of hydride as starting materials. titanium (TiH₂, 185 g) and 30% by volume of zirconium hydride (ZrH₂, 168). There was thus obtained an article based on sintered titanium whose porosity is less than 1%. The hardness measured on this article is around 850HV. The article obtained has an intense metallic shine.

Les exemples qui suivent maintenant sont des exemples préférés de la mise en oeuvre du procédé de durcissement et de coloration d'un article à base de titane selon l'invention.The examples which follow now are preferred examples of the implementation of the process for hardening and coloring of a titanium-based article according to the invention.

Exemple 1bExample 1b

Dans cet exemple on est parti de l'article à base de titane fritté et poli décrit dans l'exemple 1. L'article est placé dans un four dans lequel on fait un vide d'environ 10⁻² millibar ou contenant un flux d'argon ayant un débit de 150 ml/min. L'article est alors chauffé à une température de 1000°C par un chauffage linéaire en 3 heures. Une fois cette température atteinte, on fait circuler dans l'enceinte du four un flux de gaz comprenant en volume 50% d'azote et 50% d'argon à un débit de 150 ml/min. On maintient cette température et cette circulation de gaz pendant environ 20 minutes.In this example, we started with the article based on sintered and polished titanium described in example 1. The article is placed in an oven in which a vacuum is created of approximately 10⁻² millibar or containing a flux of with a flow rate of 150 ml / min. The article is then heated to a temperature of 1000 ° C by linear heating in 3 hours. Once this temperature has been reached, a gas flow is circulated in the oven enclosure comprising 50% nitrogen and 50% argon by volume at a flow rate of 150 ml / min. This temperature and this gas circulation are maintained for approximately 20 minutes.

L'article est ensuite refroidi progressivement jusqu'à la température ambiante.The article is then gradually cooled to room temperature.

Au cours de ce procédé de durcissement et de coloration, l'azote du flux de gaz réagit avec le carbonitrure de titane sous-stoechiométrique issu de la réaction (2) pour donner en surface un composé comprenant du carbonitrure de titane avec une nouvelle sous-stoechiométrie du carbone et de l'azote.During this hardening and coloring process, the nitrogen in the gas flow reacts with the sub-stoichiometric titanium carbonitride resulting from reaction (2) to give on the surface a compound comprising titanium carbonitride with a new sub- carbon and nitrogen stoichiometry.

On obtient alors un article à base de titane ayant, sur une épaisseur d'environ 10 microns, une dureté de l'ordre de 2800HV et un aspect métallique jaune doré proche de celui de l'or.One then obtains an article based on titanium having, over a thickness of approximately 10 microns, a hardness of the order of 2800HV and a golden yellow metallic appearance close to that of gold.

Exemple 6bExample 6b

Dans cet exemple, on a mis en oeuvre les mêmes étapes que celles décrites dans l'exemple 1b en partant d'un article à base de titane fritté et poli selon le procédé décrit plus haut et qui comprend comme produits de départ 20% en volume de poudre de carbure de titane (TiC, 98 g), 50% en volume d'hydrure de titane (TiH₂, 185 g) et 30% en volume d'hydrure de zirconium (ZrH₂, 168). L'article obtenu après durcissement et coloration présente un aspect métallique jaune doré proche de celui de l'or, et a une porosité inférieure à 1%. La dureté mesurée sur cet article est de l'ordre de 1800HV.In this example, the same steps were used as those described in Example 1b, starting from an article based on sintered and polished titanium according to the method described above and which comprises 20% by volume as starting materials. titanium carbide powder (TiC, 98 g), 50% by volume of titanium hydride (TiH₂, 185 g) and 30% by volume of zirconium hydride (ZrH₂, 168). The article obtained after hardening and coloring has a golden yellow metallic appearance close to that of gold, and has a porosity less than 1%. The hardness measured on this article is around 1800HV.

Dans ce cas, l'azote a réagi avec le carbure de zirconium sous-stoechiométrique et avec le carbure de titane sous-stoechiométrique qui résultent de la réaction (2) pour former en surface (sur une épaisseur d'environ 10 microns) un mélange de carbonitrure de titane et de produits résultant de la réaction du carbure de zirconium avec l'azote.In this case, the nitrogen reacted with the sub-stoichiometric zirconium carbide and with the sub-stoichiometric titanium carbide which result from reaction (2) to form on the surface (over a thickness of approximately 10 microns) a mixture of titanium carbonitride and of products resulting from the reaction of zirconium carbide with nitrogen.

Exemple 7Example 7

Dans cet exemple, on a mis en oeuvre les mêmes étapes que celles décrites dans l'exemple 1b avec un article à base de titane poli fabriqué selon le procédé de l'invention en utilisant comme produit de départ 5% de carbure de titane (TiC, 25 g) et 95% d'hydrure de titane (TiH₂, 352 g). Toutefois, on a utilisé dans cet exemple un flux de gaz comprenant 2% de méthane dilué dans de l'argon, l'article étant préalablement chauffé à 800°C. Dans ce cas, le carbure de titane sous-stoechiométrique qui résulte de la réaction (2) a réagi avec le carbone du flux de gaz pour former du carbure de titane stoechiométrique. La dureté mesurée sur cet article est de l'ordre de 800HV et son brillant métallique est intense.In this example, the same steps were carried out as those described in Example 1b with an article based on polished titanium manufactured according to the method of the invention using as starting material 5% of titanium carbide (TiC , 25 g) and 95% titanium hydride (TiH₂, 352 g). However, in this example, a gas flow comprising 2% of methane diluted in argon was used, the article being previously heated to 800 ° C. In this case, the sub-stoichiometric titanium carbide which results from reaction (2) reacted with the carbon of the gas flow to form stoichiometric titanium carbide. The hardness measured on this article is around 800HV and its metallic gloss is intense.

Claims (20)

Article à base de titane, caractérisé en ce qu'il est composé essentiellement d'un mélange comprenant une matrice de titane dérivé d'hydrure de titane et un élément ou une combinaison de plusieurs éléments d'addition choisis parmi l'ensemble comprenant les nitrures, les carbures, les carbonitrures, les siliciures et les borures des éléments métalliques des groupes, 3a, 4b, 5b, 6b, 7b, et 8b de la table de classification des éléments, tel que le fer, le titane, le silicium, le niobium, le molybdène, le chrome, le tungstène, le vanadium et l'aluminium ou d'un alliage des éléments métalliques ainsi que l'oxyde d'aluminium et l'oxyde de zirconium.Titanium-based article, characterized in that it is essentially composed of a mixture comprising a titanium matrix derived from titanium hydride and an element or a combination of several addition elements chosen from the group comprising nitrides , carbides, carbonitrides, silicides and borides of the metallic elements of groups, 3a, 4b, 5b, 6b, 7b, and 8b of the classification table of elements, such as iron, titanium, silicon, niobium, molybdenum, chromium, tungsten, vanadium and aluminum or an alloy of metallic elements as well as aluminum oxide and zirconium oxide. Article à base de titane selon la revendication 1, caractérisé en ce que le mélange permettant d'obtenir la matrice de titane est composé de 60 à 95% et de préférence 80 à 90% en poids d'hydrure de titane.Titanium-based article according to claim 1, characterized in that the mixture making it possible to obtain the titanium matrix is composed of 60 to 95% and preferably 80 to 90% by weight of titanium hydride. Article à base de titane selon la revendication 2, caractérisé en ce que l'hydrure de titane est partiellement remplacé par de l'hydrure de zirconium dans une proportion n'excédant pas 50%.Titanium-based article according to claim 2, characterized in that the titanium hydride is partially replaced by zirconium hydride in a proportion not exceeding 50%. Article à base de titane selon la revendication 1 ou 2, caractérisé en ce que les éléments d'addition sont choisis parmi l'ensemble comprenant le TiN, le TiC, le TiCN, le WC, le SiC, le Cr₃C₃, le TiAl, le TiB₂, le TiSi₂, le CoSi₂, le AlN, le NbC, le MoC, le TaC, et le ZrC.Titanium-based article according to claim 1 or 2, characterized in that the addition elements are chosen from the group comprising TiN, TiC, TiCN, WC, SiC, Cr₃C₃, TiAl, TiB₂, TiSi₂, CoSi₂, AlN, NbC, MoC, TaC, and ZrC. Article à base de titane selon la revendication 4, caractérisé en ce qu'il comprend 5 à 30% en poids d'un ou plusieurs des éléments d'addition choisis parmi le TiCN, le SiC, le WC, le TiC et le Cr₃C₂.Titanium-based article according to claim 4, characterized in that it comprises 5 to 30% by weight of one or more of the addition elements chosen from TiCN, SiC, WC, TiC and Cr₃C₂. Procédé de fabrication par frittage d'un article à base de titane, caractérisé en ce qu'il consiste à : - (a) se munir d'un mélange d'un liant temporaire, d'une poudre d'hydrure de titane, et d'une poudre d'un élément ou d'une combinaison de plusieurs éléments d'addition choisis parmi l'ensemble comprenant les nitrures, les carbures, les carbonitrures, les siliciures et les borures des éléments métalliques des groupes, 3a, 4b, 5b, 6b, 7b, et 8b de la table de classification des éléments, tel que le fer, le titane, le silicium, le niobium, le molybdène, le chrome, le tungstène, le vanadium et l'aluminium ou d'un alliage des éléments métalliques ainsi que l'oxyde d'aluminium et l'oxyde de zirconium, - (b) injecter le mélange obtenu dans un moule pour obtenir un article de forme souhaitée, - (c) éliminer le liant, - (d) chauffer la pièce sous une atmosphère d'hydrogène jusqu'à la température de frittage désirée, - (e) remplacer l'atmosphère d'hydrogène par le vide ou une atmosphère non réactive une fois que la température de frittage a été atteinte, et - (f) refroidir la pièce dans l'atmosphère non réactive. Process for the manufacture by sintering of a titanium-based article, characterized in that it consists of: - (a) provide with a mixture of a temporary binder, a powder of titanium hydride, and a powder of an element or a combination of several addition elements chosen from set including nitrides, carbides, carbonitrides, silicides and borides of the metallic elements of groups, 3a, 4b, 5b, 6b, 7b, and 8b of the classification table of the elements, such as iron, titanium, silicon, niobium, molybdenum, chromium, tungsten, vanadium and aluminum or an alloy of metallic elements as well as aluminum oxide and zirconium oxide, - (b) injecting the mixture obtained into a mold to obtain an article of desired shape, - (c) removing the binder, - (d) heating the part under a hydrogen atmosphere to the desired sintering temperature, - (e) replace the hydrogen atmosphere with a vacuum or a non-reactive atmosphere once the sintering temperature has been reached, and - (f) cooling the room in the non-reactive atmosphere. Procédé selon la revendication 6, caractérisé en ce que l'étape (d) comporte le chauffage de l'article à une température comprise entre 1'000 et 1'400°C.A method according to claim 6, characterized in that step (d) includes heating the article to a temperature between 1,000 and 1,400 ° C. Procédé selon la revendication 7, caractérisé en ce que l'étape (d) est réalisée pendant un temps compris entre 4 et 8 heures.Method according to claim 7, characterized in that step (d) is carried out for a time between 4 and 8 hours. Procédé selon l'une des revendications 6 à 8, caractérisé en ce qu'au cours de l'étape (d), l'hydrogène est fourni sous la forme d'un flux continu.Method according to one of claims 6 to 8, characterized in that during step (d), the hydrogen is supplied in the form of a continuous flow. Procédé selon l'une des revendications 6 à 9, caractérisé en ce qu'au cours de l'étape (e), l'article est maintenu à ladite température de frittage pendant un temps compris entre 5 et 80 minutes.Method according to one of claims 6 to 9, characterized in that during step (e), the article is maintained at said sintering temperature for a time between 5 and 80 minutes. Procédé selon l'une des revendication 6 à 10, caractérisé en ce qu'aux étapes (e) et (f) l'atmosphère non réactive comprend de l'argon ou de l'hélium.Method according to one of claims 6 to 10, characterized in that in stages (e) and (f) the non-reactive atmosphere comprises argon or helium. Procédé selon l'une des revendications 6 à 11, caractérisé en ce que l'étape (c) est réalisée chimiquement et/ou thermiquement.Method according to one of claims 6 to 11, characterized in that step (c) is carried out chemically and / or thermally. Procédé selon la revendication 12, caractérisé en ce que l'étape (c) est réalisée sous une atmosphère non réactive ou sous vide à une température inférieure à 300°C.Method according to claim 12, characterized in that step (c) is carried out under a non-reactive atmosphere or under vacuum at a temperature below 300 ° C. Procédé selon la revendication 12, caractérisé en ce que l'étape (c) est réalisée pendant un temps compris entre 2 et 9 heures.Method according to claim 12, characterized in that step (c) is carried out for a time between 2 and 9 hours. Procédé selon la revendication 12, caractérisé en ce que le liant est un polymère thermique et en ce que l'étape (c) comprend la décomposition chimique du polymère thermique par une vapeur d'acide.Process according to claim 12, characterized in that the binder is a thermal polymer and in that step (c) comprises the chemical decomposition of the thermal polymer by an acid vapor. Procédé selon l'une quelconque des revendications 6 à 15, caractérisé en ce qu'il comprend une étape supplémentaire au cours de laquelle l'article est soumis à un polissage spéculaire.Method according to any one of claims 6 to 15, characterized in that it comprises an additional step during which the article is subjected to specular polishing. Procédé de durcissement et de coloration en surface d'un article à base de titane obtenu selon le procédé défini par l'une des revendications 6 à 15, caractérisé en ce qu'il consiste à : - (g) placer l'article dans un four, - (h) chauffer l'article à une température déterminée et maintenir l'article à cette température pendant un temps déterminé, et - (i) faire circuler un flux de gaz comprenant du carbone et/ou de l'azote autour de l'article pour former, à la surface de l'article du carbure de titane, du nitrure de titane, du carbonitrure de titane, ou un mélange de ces derniers. Method for hardening and coloring on the surface of a titanium-based article obtained according to the method defined by one of claims 6 to 15, characterized in that it consists of: - (g) place the article in an oven, - (h) heating the article to a determined temperature and maintaining the article at this temperature for a determined time, and (i) circulating a gas flow comprising carbon and / or nitrogen around the article to form, on the surface of the article titanium carbide, titanium nitride, titanium carbonitride, or a mixture of these. Procédé de durcissement et de coloration en surface selon la revendication 17, caractérisé en ce qu'au cours de l'étape (h) l'article est amené à une température comprise entre 600 et 1000°C et de préférence à une température de 800° et en ce que cette température est maintenue pendant 10 à 30 minutes.Surface hardening and coloring method according to claim 17, characterized in that during step (h) the article is brought to a temperature between 600 and 1000 ° C and preferably to a temperature of 800 ° and in that this temperature is maintained for 10 to 30 minutes. Procédé de durcissement et de coloration en surface selon la revendication 17 ou 18, caractérisé en ce que le flux de gaz comprenant du carbone comprend le méthane et le propane.Surface hardening and coloring process according to claim 17 or 18, characterized in that the gas stream comprising carbon includes methane and propane. Procédé de durcissement et de coloration en surface selon l'une des revendications 17 à 19, caractérisé en ce qu'il est appliqué à un article à base de titane poli obtenu selon le procédé défini à la revendication 16.Surface hardening and coloring process according to one of Claims 17 to 19, characterized in that it is applied to an article based on polished titanium obtained according to the process defined in Claim 16.
EP95103385A 1994-03-18 1995-03-09 Titanium based article with high hardness and high gloss process for preparing and process for hardening and colouring the surface of this article Withdrawn EP0672489A1 (en)

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Application Number Priority Date Filing Date Title
CH81494A CH687622A5 (en) 1994-03-18 1994-03-18 Article based on titanium, ductile hardness and high gloss, method of making such an article and curing process and for coloring a surface of such an article.
CH814/94 1994-03-18
FR9404221A FR2718376B1 (en) 1994-04-11 1994-04-11 Titanium-based, ductile article having high hardness and high gloss, method for manufacturing such an article and method for hardening and coloring a surface of such an article.
FR9404221 1994-04-11

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JP5312431B2 (en) * 2010-10-30 2013-10-09 株式会社セブン・セブン Method for manufacturing vacuum insulated double container
JP5297436B2 (en) * 2010-10-30 2013-09-25 株式会社セブン・セブン Method for manufacturing vacuum insulated double container
KR101525095B1 (en) * 2013-08-12 2015-06-02 (주)엠티아이지 Injection molding method using powder
CN104525948B (en) * 2014-12-23 2017-03-15 金堆城钼业股份有限公司 A kind of preparation method of molybdenum alloy electrode
CN107142388B (en) * 2017-04-11 2018-11-27 昆明理工大学 A kind of preparation method of Ti-13Nb-13Zr alloy
EP3974405A1 (en) * 2020-09-25 2022-03-30 The Swatch Group Research and Development Ltd Ceramic decorative item

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1011152B (en) * 1953-03-16 1957-06-27 Renault Process for the production of hard, tough and heat-resistant titanium alloys
JPS6176628A (en) * 1984-09-21 1986-04-19 Hitachi Ltd Ceramics-metal composite material
US4851053A (en) * 1988-05-06 1989-07-25 The United States Of America As Represented By The Secretary Of The Air Force Method to produce dispersion strengthened titanium alloy articles with high creep resistance
EP0424739A2 (en) * 1989-10-24 1991-05-02 BASF Aktiengesellschaft Process for producing preforms from ceramic or metallic fibers

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1011152B (en) * 1953-03-16 1957-06-27 Renault Process for the production of hard, tough and heat-resistant titanium alloys
JPS6176628A (en) * 1984-09-21 1986-04-19 Hitachi Ltd Ceramics-metal composite material
US4851053A (en) * 1988-05-06 1989-07-25 The United States Of America As Represented By The Secretary Of The Air Force Method to produce dispersion strengthened titanium alloy articles with high creep resistance
EP0424739A2 (en) * 1989-10-24 1991-05-02 BASF Aktiengesellschaft Process for producing preforms from ceramic or metallic fibers

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
CHEMICAL ABSTRACTS, vol. 119, no. 12, 20 September 1993, Columbus, Ohio, US; abstract no. 122411, KYOGOKU, HIDEKI ET AL: "Sintering behavior of titanium compacts with the addition of titanium hydride powder by using injection moldings" *
CHEMICAL ABSTRACTS, vol. 78, no. 26, 2 July 1973, Columbus, Ohio, US; abstract no. 163134, KURATOMI, TATSUO: "Manufacture of superhard sintered tungsten alloys" *
FUNTAI OYOBI FUNMATSU YAKIN (1993), 40(4), 439-43 CODEN: FOFUA2;ISSN: 0532-8799 *
PATENT ABSTRACTS OF JAPAN vol. 010, no. 245 (C - 368) 22 August 1986 (1986-08-22) *

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