Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C3/00—Glass compositions
  • C03C3/04—Glass compositions containing silica
  • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C10/00—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition
  • C03C10/0009—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition containing silica as main constituent
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C10/00—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C10/00—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition
  • C03C10/0018—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition containing SiO2, Al2O3 and monovalent metal oxide as main constituents
  • C03C10/0027—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition containing SiO2, Al2O3 and monovalent metal oxide as main constituents containing SiO2, Al2O3, Li2O as main constituents
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C3/00—Glass compositions
  • C03C3/04—Glass compositions containing silica
  • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
  • C03C3/083—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound
  • C03C3/085—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal

Definitions

• the present invention relates to glass and glass-ceramic materials, articles and method of making the same.
• the present invention relates to glass-ceramic materials having ?-quartz or ?-spodumene as the predominant crystalline phase having a high ⁇ -OH level.
• the present invention is useful, for example, in the production of glass- ceramic articles such as cooktops, cook utensils, stove windows, and the like.
• BACKGROUND OF THE INVENTION [0002]
• numerous glass-ceramic materials and articles have been described, for use such as cooktops, cooking utensils, stove windows and the like. [0003] In United States Patent No.
• the glass-ceramic mateiral is obtained by heat treatment of the glass precursor, which comprises a step of crystallization at a temperature on the order of 1,070°C to 1,090°C. The higher the temperature of this crystallization step is, the more the opacity of the material.
• the glass precursor of the glass-ceramics of the invention are also suitable for obtaining efficient glass-ceramics of main crystalline phase of ⁇ -quaxtz. It therefore enables the manufacture of various transparent or opaque products from the same glass precursor composition. This flexibility of the method in question is highly desirable in the art.
• a transparent, translucent or opaque glass-ceramic material containing, as main crystalline phase, solid solution of ?-quartz or /?-spodumene, characterized in that: (i) it essentially has the following composition, expressed as percentages by weight of oxides: 65 to 70% of SiO 2 18 to 23% ofAl 2 O 3 > 4 to 5% of Li 2 O 0 to ⁇ l% ofMgO 1 to 3% of ZnO 0 to 2% of BaO 1.8 to 4% ofTiO 2 1 to 2.5% of ZrO 2 0.4 to 1% of K 2 O and or Na 2 O; with, advantageously, an effective and non-excess amount of at least one fining agent; and (ii) it has a ?-OH value of higher than 0.2 mm "1 , preferably higher than 0.4 mm "1 .
• the composition of the glass-ceramic contains As O 3 and/or Sb 2 O 3 , as fining agent, in the following percentages by weight: As 2 O 3 0 - 1.5 Sb 2 O 3 0 - 1.5 with As 2 O 3 + Sb 2 O 3 0.5 - 1.5.
• the composition of the glass-ceramic material further comprises an effective amount of at least one colorant, advantageously selected from CoO, Cr 2 O 3 , Fe 2 O , MnO 2 , NiO, V 2 O 5) CeO 2 and their mixtures.
• an article made from a glass-ceramic material of the present invention described above which is preferably selected from the group consisting of a cook-top, a cooking utensil, a microwave oven plate, a fireplace window, a fire-door or fire-window, a pyrolysis oven window and a catalysis oven window.
• a third aspect of the present invention involves an inorganic glass, which is a precursor of a glass-ceramic material according to the present invention, characterized in that: (i) it essentially has the following composition, expressed as percentages by weight of oxides: 65 to 70% of SiO 2 18 to 23% ofAl 2 O 3 > 4 to 5% ofLi 2 O 0 to ⁇ l% ofMgO 1 to 3% of ZnO 0 to 2% of BaO 1.8 to 4% ofTiO 2 1 to 2.5% of ZrO 2 0.4 to 1% of K 2 O and/or Na 2 O; with, advantageously, an effective and non-excess amount of at least one fining agent; and (ii) it has a ⁇ - R value of higher than 0.2 mm "1 , preferably higher than 0.4 mm "1 .
• a fourth aspect of the present invention is a method of preparing a glass- ceramic material or article of the present invention described above, characterized in that it comprises heat-treating a crystallizable inorganic glass precursor of the glass-ceramic described above under conditions which ensure its ceramization.
• the heat treatment comprises a step of crystallization at a temperature of between 1,050 and 1,200°C.
• the heat treatment comprises a step of crystallization at a temperature of between 840 and 900°C.
• the present invention has the surprising benefit that, because of the choice of composition, notwithstanding the high water content of at least 0.2 mm "1 , preferably at least 0.4 mm "1 in the precursor glass, the glass-ceramic composition comprising ⁇ - spodumene solid solution as the main crystalline phase can be obtained at a high ceramming temperature without cracking and reduction in mechanical strength. Further, the cerammed material and/or articles have a low thermal expansion. In addition, effective glass-ceramic materials and/or articles comprising ?-quartz solid solution as the main crystalline phase can be produced as well from the precursor glass of the present invention.
• FIG. 1 is a diagram showing the transmission curves of the glass-ceramic materials in the Examples of the present invention and Comparative Examples.
• the glass-ceramic materials of the present invention which can exist in transparent, translucent (opalescent) or opaque form, i.e., which contain ?-quartz or ⁇ - spodumene as main crystalline phase, are characterized in that they essentially have the following composition, expressed in percentages by weight of oxides: 65 to 70% of SiO 2 18 to 23% ofAl 2 O 3 > 4 to 5% ofLi 2 O 0 to ⁇ l% ofMgO 1 to 3% of ZnO 0 to 2% of BaO 1.8 to 4% ofTiO 2 1 to 2.5% ofZrO 2 0.4 to 1% of K 2 O and or Na 2 O; with, advantageously, an effective and non-excess amount of at least one fining agent, and in that it comprises a ⁇ -O ⁇ .
• MgO over 1% of MgO and the thermal expansion is not acceptable
• ZnO ZnO enables, with Li 2 O, the coefficient of thermal expansion of the glass-ceramics to be adjusted. Thus, it must be incorporated at less than 1%. At too high a content (> 3%), a risk is taken of crystallizing other crystalline phases, such as spinels, which have a high thermal expansion
• BaO BaO is an optional element which enables the viscosity of the glass precursor to be adjusted. It remains in the amorphous phase of the glass-ceramic. If it is incorporated in an amount which is greater than 2%, it is difficult to keep a low thermal expansion;
• TiO 2 and ZrO 2 are incorporated as nucleation agents. If they are incorporated in too low an amount, the precursor glass does not crystallize; if they are incorporated in too high an amount, the devitrification, upon cooling, can be difficult to control;
• Na 2 O and K O enable the problems of mechanical strength and surface cracking to be limited. These constituents remain in the amorphous phase of the glass- ceramic. If they are incorporated in too great an amount, they have a harmful effect upon the thermal expansion. [0031] Within the composition set forth, it was possible, in a non-obvious manner, to take advantage of the beneficial action, of Al 2 O and/or K 2 O and/or Na 2 O, on the mechanical properties (also on the absence of cracks) while at the same time limiting, even compensating for, mainly by virtue of Li 2 O, their harmful action on the thermal expansion. [0032] The optional constituents, MgO and BaO, when they are present, are generally present at at least 0.1% by weight.
• composition specified above advantageously contains an effective and non-excess amount of at least one fining agent.
• the person skilled in the art knows well how to manage the incorporation of this type of compounds within the glass precursor. In general, it is incorporated at less than 3% by weight, rather at less than 2% by weight of this type of compounds.
• As 2 O 3 and/or Sb 2 O 3 are in general incorporated as fining agent in the following amounts: As 2 O 3 0 - 1.5 Sb 2 O 3 0 - 1.5 with As 2 O 3 + Sb 2 O 3 0,5 - 1.5 (% by weight).
• the glass-ceramic of the invention may be colored or not. In order for it to have a real coloration, it contains, in addition to its constituent elements listed above, an effective amount, which does not in general exceed 2% by weight, of at least one colorant.
• Said colorant(s) is(are) advantageously selected from CoO, Cr 2 O 3 , Fe 2 O 3 , MnO , NiO,
• As colored glass-ceramics (black, transparent) of the invention those which have the composition by weight indicated above are more particularly preferred with, in addition, 0.03 (advantageously 0.05) to 1% by weight of V O 5 and the following condition:
• the glass-ceramic materials of the invention which are efficient in terms of transmission, of mechanical strength and of thermal expansion, can contain relatively high water contents ( ⁇ -OH > 0.2 mm "1 , even /?-OH > 0.4 mm "1 ), which do not notably impose any constraint, during their preparation process. No particular precautions are required. These affirmations are confirmed by the Examples below.
• the glass-ceramic materials of the invention can exist with a predominant crystalline phase of ⁇ -quartz or 7-spodumene solid solution.
• the glass-ceramics of the invention are glass-ceramics having a predominant crystalline phase of ?-spodumene solid solution.
• Such glass- ceramics when they contain an effective amount of at least one colorant selected from CeO 2 , MnO 2 and Fe 2 O 3 , have a beige color.
• the present invention relates to crystallizable inorganic glasses which are precursors of the glass-ceramics described above.
• Said inorganic glasses, which are crystallizable and are precursors of the glass-ceramics above essentially have the following composition, expressed in percentages by weight of oxides: 65 to 70% of SiO 2 18 to 23% ofAl 2 O 3 > 4 to 5% of Li 2 O 0 to ⁇ l% ofMgO 1 to 3% of ZnO 0 to 2% of BaO 1.8 to 4% ofTiO 2 l to 2.5% ofZrO 2 0.4 to 1% of K 2 O and/or Na 2 O; with, advantageously, an effective and non-excess amount of at least one fining agent.
• the glass has advantageously a ⁇ -OH value higher than 0.2 mm "1 , preferably higher than 0.4 mm "1 .
• Said inorganic glasses are optionally colored. According to what has been seen above, they can notably contain an effective amount of at least one of the following colorants: CoO, Cr 2 O 3 , Fe 2 O 3 , MnO 2 , NiO, V 2 O 5 and CeO 2 .
• the present invention relates to articles made from a glass-ceramic materials as described above.
• the articles in question can notably be selected from the group consisting of a cook-top, a cooking utensil, a microwave oven plate, a fireplace window (fireguard plate), a fire-door or fire-window or a pyro lysis oven window or catalysis-oven window. They advantageously are cook-tops.
• the present invention relates to the methods of preparation of glass-ceramic materials and articles.
• Said methods constitute analogous methods, which are implemented characteristically with crystallizable inorganic glasses having the weight composition set forth above.
• the glass-ceramic materials and articles of the invention are obtained by heat treating a crystallizable inorganic glass precursor, as characterized above, this heat treatment being implemented under conditions which ensure the ceramization of said glass precursor.
• the glass-ceramic articles of the invention are obtained by such a heat treatment after shaping the crystallizable inorganic glass precursor in question.
• the shaping is a classical step. It can notably be pressing or rolling. It can notably be a shaping which is intended to confer the shape of a plate.
• the heat treatment in question classically comprises a rise in temperature, which is generally in stages, up to the crystallization temperature maintained over an adequate period of time. Said heat treatment of the invention generally lasts less than 2 hours. This is another advantageous point of the present invention.
• said heat treatment In order to obtain a glass-ceramic the main crystalline phase of which isf5-spodumene solid solution, said heat treatment generally comprises the crystallization step at a temperature of between 1,050 and 1,200°C. [0052] In order to obtain a glass-ceramic of the invention, the main crystalline phase of which is /J-quartz solid solution, said heat treatment generally comprises the crystallization step at a temperature of between 840 and 900°C.
• Example I the importance of which more particularly emerges upon consideration of Comparative Examples 1 and 2
• Examples II and III the importance of which more particularly emerges upon consideration of Comparative Example 3.
• Example I the present invention
• Comparative Examples 1 and 2 [0056] Said Comparative Examples 1 and 2 illustrate the prior art.
• the MOR values were measured according to ASTM standard
• MOR values 144 MPa and 124 MPa, respectively.
• Example 1 except that its OH content is much lower. Consequently, the glass-ceramics obtained from said glass - glass-ceramics comprising ?-spodumene as the main crystalline phase, white in color and slightly translucent (that obtained after the Ceramization
• Schedule 2 is a little more opaque than that obtained after the Ceramization Schedule 1) - have higher MOR values: 209 MPa and 294 MPa, respectively.
• the glass of Example I is a glass precursor of the invention. Despite a significant OH content (almost identical to that of the glass of Comparative Example 1), it does enable efficient glass-ceramics to be obtained, with regard to both: - their low thermal expansion values, and - their high MOR values (191 MPa and 195 MPa).
• the glass-ceramics of the invention obtained by the Ceramization Schedules 1 and 2 are glass-ceramics of ⁇ -spodumene, white in color and slightly translucent.
• the glass-ceramic of the invention obtained by the Ceramization Schedule 3 is a glass-ceramic of ⁇ -quartz. It is transparent.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
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• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Life Sciences & Earth Sciences (AREA)
• Organic Chemistry (AREA)
• Ceramic Engineering (AREA)
• Crystallography & Structural Chemistry (AREA)
• Dispersion Chemistry (AREA)
• Glass Compositions (AREA)
• Electric Ovens (AREA)

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• 2003
  • 2003-12-17 FR FR0314834A patent/FR2864071A1/fr not_active Withdrawn
• 2004
  • 2004-12-10 US US11/008,836 patent/US7153795B2/en not_active Expired - Lifetime
  • 2004-12-17 JP JP2006544372A patent/JP4925187B2/ja not_active Expired - Fee Related
  • 2004-12-17 WO PCT/EP2004/014463 patent/WO2005058766A1/en not_active Ceased
  • 2004-12-17 ES ES04804063T patent/ES2404281T3/es not_active Expired - Lifetime
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