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    • 专利摘要:
    Sintered product exhibiting: - a chemical analysis such as, in percentages by mass based on the oxides, - ZrO2 partially stabilized with CeO2 and Y2O3: complement to 100%, - Al2O3: 3 - 22% - additive chosen from CaO, oxides manganese, ZnO, La2O3, praseodymium oxides, SrO, copper oxides, Nd2O3, BaO, iron oxides, and their mixtures: 0.2 - 6%, - impurities: <2%, CeO2 and Y2O3 being present in amounts such as, as a molar percentage based on the sum of ZrO2, CeO2 and Y2O3, - CeO2: 2.5 - 6.5 mol% and - Y2O3: 0.5-2 mol%, provided that, if Al2O3 <10%, the following formula (1) is respected: CeO2> -0.57.Al2O3 + 8.2, (1) CeO2 being expressed as a molar percentage on the basis of the sum of ZrO2, CeO2 and Y2O3 and Al2O3 being expressed as a percentage by mass on the basis of the mass of the product, - a particle size distribution such as, - the average size of the grains having a form factor of less than 2.5, or "collected grains", being less less than 2 µm, - the average length of the elongated aluminous nodules being less than 20 µm.
    公开号:FR3039540A1
    申请号:FR1557315
    申请日:2015-07-30
    公开日:2017-02-03
    发明作者:Thomas Perie
    申请人:Saint Gobain Centre de Recherche et dEtudes Europeen SAS；
    IPC主号:
    专利说明:

    Sintered product based on alumina and zirconia
    Technical field The invention relates to a sintered product based on alumina and zirconia, a particulate mixture making it possible to obtain such a product, as well as a process for manufacturing said product.
    Background of the invention
    Among refractory products, a distinction is made between molten and cast products and sintered products. Unlike sintered products, molten and cast products most often include a very abundant intergranular vitreous phase which fills a network of crystallized grains. The problems encountered in their respective applications by sintered products and by molten and cast products, and the technical solutions adopted to solve them, are therefore generally different. Moreover, due to the significant differences between the manufacturing processes, a composition developed to produce a molten and cast product is not a priori usable as it is to produce a sintered product, and vice versa.
    The sintered products are obtained by mixing suitable raw materials and then raw shaping of this mixture and firing of the resulting green part at a temperature and for a time sufficient to obtain the sintering of this green part.
    Sintered products, depending on their chemical composition, have different properties and are therefore intended for a wide variety of industries.
    Among ceramic sintered products, quadratic yttriated zirconia products, typically comprising a molar amount of Y203 equal to 3%, exhibit high tensile stress and hardness.
    The cerium zirconia products, typically comprising a molar amount of CeO 2 equal to 12%, exhibit a very high toughness, higher than that of the yttriated zirconia products, but a lower breaking stress and a lower hardness.
    There is therefore a need for a sintered ceramic product exhibiting a better compromise between hardness, toughness and modulus at break.
    One aim of the invention is to meet, at least partially, this need. Summary of the invention The invention provides a sintered product exhibiting: a chemical analysis such that, in percentages by mass based on the oxides,
    Zr02 partially stabilized with Ce02 and Y203: complement to 100%,
    Al203: 3-22% additive chosen from CaO, manganese oxides, ZnO, La203) praseodymium oxides, SrO, copper oxides, Nd203,
    BaO, iron oxides, and their mixtures: 0.2 - 6%, impurities: <2%,
    Ce02 and Y203 being present in amounts such as, as a mole percentage based on the sum of Zr02, Ce02 and Y203,
    Ce02: 2.5 - 6.5 mol% and Y203: 0.5-2 mol%, provided that, if Al2O3 <10%, the following formula (1) is respected:
    Ce02> -0.57.AI2O3 + 8.2, (1)
    Ce02 being expressed as a molar percentage based on the sum of Zr02, Ce02 and Y203 and
    Al203 being expressed as a percentage by mass based on the mass of the product, a particle size distribution such as the average size of grains having a form factor of less than 2.5, or "picked grains", being less than 2 µm, the length average of the elongated aluminous nodules being less than 20 µm, an elongated aluminous nodule being a structure having a form factor greater than or equal to 2.5 and consisting of an aluminous grain or of several adjacent aluminous grains, an aluminous grain being a grain consisting, for more than 40% of its mass, of AI203 and said additive.
    The inventors have in particular discovered that an excellent compromise between toughness, hardness and tensile strength was possible by combining low contents of cerium oxide and of alumina.
    A sintered product according to the invention can in particular be produced according to a process according to the invention described below.
    A sintered product according to the invention can also exhibit one or more of the following optional characteristics: the molar content of Y203 is preferably less than 1.9%, preferably less than 1.7%, preferably less than 1.5% , and / or preferably greater than 0.6%, preferably greater than 0.8%, preferably greater than 1%, as a molar percentage based on the sum of ZrO 2, CeO 2 and Y 2 O 3; - The Al 2 O 3 alumina content is preferably less than 19%, preferably less than 16%, and / or preferably greater than 5%, preferably greater than 8%, preferably greater than 10%, in percentage by mass on the base of oxides; - the molar content of CeO 2 is preferably less than 6%, preferably less than 5.5%, preferably less than 5%, preferably less than 4.5%, preferably less than 4.2%, preferably less than 4%, preferably less than 3.8%, and / or greater than 3%, in mole percent based on the sum of ZrO2, CeO2 and Y203; - the additive is preferably chosen from CaO, manganese oxides, La203, SrO, BaO and their mixtures, preferably from CaO, manganese oxides, and mixtures thereof; - preferably, the additive is a mixture of CaO on the one hand and one of several manganese oxide (s) on the other hand; - the additive content is preferably greater than 0.3%, preferably greater than 0.4%, preferably greater than 0.5%, and / or preferably less than 5%, preferably less than 4%, as a percentage by mass based on the oxides; - in one embodiment, the additive comprises CaO, the CaO content being less than 4%, preferably less than 3%, preferably less than 2%, preferably less than 1%, or even less than 0.8 %, or even less than 0.6%, as a percentage by mass based on the oxides; - In one embodiment, the additive comprises La203, the La203 content being less than 4%, preferably less than 3%, preferably less than 2%, preferably less than 1%, or even less than 0.8 %, or even less than 0.6%, as a percentage by mass based on the oxides; - in one embodiment, the additive comprises Nd203, the Nd203 content being less than 4%, preferably less than 3%, preferably less than 2%, preferably less than 1%, or even less than 0.8 %, or even less than 0.6%, as a percentage by mass based on the oxides; - In a preferred embodiment, the additive is a mixture of one or more oxide (s) of manganese and of CaO, the content of manganese oxide (s) expressed in the MnO form being greater than 0.2% , preferably greater than 0.3%, and / or preferably less than 4%, preferably less than 3%, preferably less than 2%, preferably less than 1%, preferably less than 0.8%, and the CaO content preferably being greater than 0.2%, and / or less than 4%, preferably less than 3%, preferably less than 2%, preferably less than 1%, preferably less than 0, 8%, preferably less than 0.5%, as a percentage by mass based on the oxides; the content of impurities is preferably less than 1.0%, preferably less than 0.8%, preferably less than 0.5%, or even less than 0.3%, as a percentage by mass based on the oxides; In one embodiment, the impurities consist of oxides; - in one embodiment, - the alumina content is preferably greater than 3%, preferably greater than 5%, preferably greater than 8%, preferably greater than 10%, and less than 19%, preferably less than 16% and - the Zr02 content partially stabilized with Ce02 and Y203 represents the complement to 100%,
    Ce02 and Y203 being present in amounts such that, as a molar percentage based on the sum of Zr02, Ce02 and Y203, - the molar content of Y203 is less than 2%, preferably less than 1.9%, preferably less 1.7%, preferably less than 1.5% and greater than 0.6%, preferably greater than 0.8%, preferably greater than 1%, and - the molar CeO2 content is less than 6% , preferably less than 5.5%, preferably less than 5%, preferably less than 4.5%, preferably less than 4.2%, preferably less than 4%, preferably less than 3.8% and greater than 3%, and - the additive content is greater than 0.2%, preferably greater than 0.3%, preferably greater than 0.4%, or even greater than 0.5% or greater than 0, 6%, and less than 5%, preferably less than 4%, preferably less than 3%, preferably less than 2.5%, preferably less than 2%, or even less than 1.5%, or even less than 1%, in percentage in ma sse on the basis of the oxides, and - the impurity content is less than 1.0%, preferably less than 0.8%, preferably less than 0.5%, or even less than 0.3%, in percentage by mass on the basis of oxides;
    In a preferred embodiment, the alumina content is greater than 3%, preferably greater than 5%, preferably greater than 8%, preferably greater than 10%, and less than 19%, preferably less than 16% , and - the Zr02 content partially stabilized with Ce02 and Y203 represents the complement to 100%,
    CeO2 and Y203 being present in amounts such that, in mole percent based on the sum of ZrO2, CeO2 and Y203, the molar content of Y203 is less than 2%, preferably less than 1.9%, preferably less 1.7%, preferably less than 1.5%, and greater than 0.6%, preferably greater than 0.8%, preferably greater than 1%, and the molar content of CeO2 is less than 6% , preferably less than 5.5%, preferably less than 5%, preferably less than 4.5%, preferably less than 4.2%, preferably less than 4%, preferably less than 3.8% and greater than 3%, and - the additive is a mixture of a manganese oxide and CaO, the manganese oxide content expressed in the MnO form being greater than 0.2%, preferably greater than 0.3 % and less than 4%, preferably less than 3%, preferably less than 2%, preferably less than 1%, preferably less than 0.8%, and the CaO content being greater than 0.2% and inf greater than 4%, preferably less than 3%, preferably less than 2%, preferably less than 1%, preferably less than 0.8%, preferably less than 0.5%, as a percentage by mass on the based on the oxides, and - the impurity content is less than 1.0%, preferably less than 0.8%, preferably less than 0.5%, or even less than 0.3%, as a percentage by mass on the basis oxides; - the average size of the grains collected is less than 1.5 μm, preferably less than 1 μm, preferably less than 0.5 μm and / or preferably greater than 0.1 μm, preferably greater than 0.2 μm ; - In a preferred embodiment, more than 95%, preferably more than 97%, preferably more than 99% by number of the grains collected are grains of partially stabilized zirconia and / or grains consisting for more than 40% of their mass of alumina; the average length of the elongated aluminous nodules is less than 18 μm, preferably less than 15 μm, or even less than 10 μm and / or greater than 1 μm, preferably greater than 2 μm, preferably greater than 5 μm; more than 50%, preferably more than 60%, preferably more than 70%, preferably more than 80% by number of the elongated aluminous nodules have a form factor greater than or equal to 3, or even greater than or equal to 4; the sintered product has a ratio H, equal to the ratio of the area covered by the elongated aluminous nodules to the area covered by said elongated aluminous nodules and the collected grains comprising more than 40% by mass of alumina, expressed in percentages, greater than 5%, preferably greater than 10%, preferably greater than 20%, and / or preferably less than 95%, preferably less than 90%, preferably less than 80%; more than 30%, more than 40%, more than 60%, more than 80%, more than 90% by number of the elongated aluminous nodules have a generally rectilinear shape; - Said elongated aluminous nodules comprise the element Al and the metal cations of the oxides added as an additive (Ca and / or Mn and / or Zn and / or La and / or Pr and / or Sr and / or Cu and / or Nd and / or Ba and / or Fe). - the bulk density of the sintered product is preferably greater than 5.4 g / cm3, or even greater than 5.5 g / cm3, or even greater than 5.6 g / cm3 and / or preferably less than 6.2 g / cm3, or even less than 6.1 g / cm3, or even less than 6 g / cm3, or even less than 5.8, g / cm3; the relative density of the sintered product is preferably greater than 95%, preferably greater than 97%, preferably greater than 98%, preferably greater than 99%. The invention also relates to a process for manufacturing a sintered product according to the invention, comprising the following steps: a) preparation of a starting charge comprising a particulate mixture having a median size of less than 1.0 μm, and of which the composition is adapted so as to obtain, at the end of step c), a sintered product according to the invention, b) shaping of the starting charge so as to obtain a preform, c) sintering of the preform at a sintering temperature greater than 1300 ° C. so as to obtain a sintered product according to the invention.
    A process according to the invention may also include one or more of the following optional characteristics: - in step a), a grinding stage is carried out, preferably by co-grinding, so as to obtain a median size preferably less than 0, 8 μm, preferably less than 0.6 μm, preferably less than 0.5 μm, even less than 0.3 μm, or even less than 0.2 μm; - The method preferably comprises, in step b) shaping by strip casting or by pressing, preferably by uni-axial pressing, by hot pressing or by isostatic pressing; - in step c), the sintering temperature is preferably less than 1600 ° C, preferably less than 1550 ° C, preferably less than 1500 ° C and / or greater than 1350 ° C, preferably greater than 1400 ° C. The invention also relates to a particulate mixture comprising particles of ZrO2, particles of Al2O3, particles of CeO2, particles of Y203, and particles of CaO and / or particles of one or more oxide (s). manganese and / or particles of ZnO and / or particles of La203 and / or particles of one or more oxide (s) of praseodymium and / or particles of SrO and / or particles of one or more oxide (s) copper and / or particles of Nd203 and / or particles of BaO and / or particles of one or more oxide (s) of iron and / or particles of precursors of these oxides and / or particles of several of these oxides and / or precursors of these oxides, the particulate mixture exhibiting a chemical composition suitable for the manufacture of a sintered product according to the invention.
    Advantageously, such a particulate mixture is ready for use.
    A particulate mixture according to the invention can in particular be packaged in bags.
    Preferably, the manganese oxide is selected from MnO, MnO2, Mn2O3, Mn304 and mixtures thereof. Preferably, the manganese oxide is selected from MnO, Mn304 and mixtures thereof.
    Preferably, the praseodymium oxide is Pr6On.
    Preferably, the copper oxide is CuO.
    Preferably, the iron oxide is selected from FeO, Fe203 and mixtures thereof.
    Preferably, said particulate mixture comprises particles of ZrO2, Al2O3, CeO2, Y203, particles of CaO and particles of a manganese oxide, preferably MnO and / or Mn304, and / or particles of precursors of these oxides, and / or particles of several of these oxides and / or precursors of these oxides.
    Preferably, the median size of said particulate mixture is less than 1 μm, preferably less than 0.8 μm, preferably less than 0.6 μm, preferably less than 0.5 μm, or even less than 0.3 μm, or even less than 0.2 μm.
    Preferably, the specific surface of said particulate mixture is less than 20 m2 / g, preferably less than 15 m2 / g, and / or preferably greater than 5 m2 / g. Finally, the invention relates to a device chosen from: a mechanical wearing part, preferably chosen from the group formed by a shutter and a shutter seat of a valve, a pump rotor, a pump seal and a pump body, a dental article, in particular a tooth prosthesis or a part of an orthodontic appliance, an optical fiber connector, in particular a tip (or "ferrule" in English) or a sleeve (or "sleeve" in English English), - a decorative item chosen from the group formed by a jewel, a watch, a bracelet, a necklace, a ring, a brooch, a tie pin, a handbag, a telephone, a piece of furniture, a household utensil , a handle, a button, a veneer, a visible part of a consumer good equipment, a part of an eyeglass frame, a tableware and a frame, said device comprising a sintered product according to the invention or manufactured in starting from a particulate mixture according to the invention. Definitions - By “particle” is meant an individualized solid product in a powder. - “Sintering” is the consolidation by heat treatment at more than 1100 ° C. of a granular agglomerate, possibly with a partial or total melting of some of its constituents (but not all of its constituents). - The term "median size" of a powder, generally denoted by D50, is the size dividing the particles of this powder into first and second populations equal in mass, these first and second populations comprising only particles having a size greater than or equal, or less, respectively, than the median size. The median size can for example be measured using a laser particle size analyzer. - The term "average size" of the grains of a sintered product refers to the dimension measured using a "Mean Linear Intercept" method. One such measurement method is described in ASTM E1382. - The manganese oxides include in particular MnO, Mn203, Mn02 and Mn304. - The iron oxides include in particular FeO, Fe203, Fe304. - The praseodymium oxides include in particular Pr203. - Copper oxides include CuO and Cu20 in particular. - By "impurities" is meant the inevitable constituents, necessarily introduced with the raw materials. In particular, the compounds belonging to the group of oxides, nitrides, oxynitrides, carbides, oxycarbons, carbonitrides and metallic species of sodium and other alkalis, vanadium and chromium are impurities. As examples, mention may be made of Na2O or MgO. In contrast, hafnium oxide is not considered an impurity. - Hf02 is not chemically dissociable from Zr02. In the chemical composition of a product containing zirconia, Zr02 therefore denotes the total content of these two oxides. However, according to the present invention, HfO2 is not added intentionally in the starting charge. Hf02 therefore only designates traces of hafnium oxide, this oxide always being naturally present in zirconia sources at levels generally less than 2%. For the sake of clarity, the content of zirconia and traces of hafnium oxide can therefore be referred to interchangeably as ZrO 2 + HfO 2 or by ZrO 2, or by “zirconia content”. - By "precursor" of an oxide is meant a constituent capable of supplying said oxide during the manufacture of a sintered product according to the invention. For example, barium carbonate BaCO3 is a possible precursor of BaO. - We call "shape factor of a grain or a nodule", the ratio between the largest dimension of the grain or the nodule, or "length" and the largest dimension measured perpendicular to the direction of said largest dimension , or "width". These dimensions are measured in an observation plane of a polished section of the sintered product, conventionally on electron microscopy images of this section. - The term “elongated nodule” means a nodule having a form factor F greater than or equal to 2.5. - By "absolute density" of a sintered product according to the invention is meant the absolute density conventionally calculated using a law of mixtures, from a chemical analysis of said sintered product according to the invention , considering that all the oxides of yttrium and cerium stabilize the zirconia, and without taking into account the additives and the impurities. The absolute density of the zirconia partially stabilized at Y203 and Ce02 is calculated according to the teaching of the document “Phase transformation and lattice constants of zirconia solid solutions in the System Y20r-Ce02-Zr02”, Urabe et al., Materials Science Forum Vols . 34-36 (1988) pp 147-152. - By "relative density" of a product is meant the ratio equal to the apparent density divided by the absolute density, expressed as a percentage.
    Unless otherwise indicated, all the percentages relating to the composition of a product or relating to a starting charge are weight percentages based on the oxides and all the percentages of Ce02 and Y203 are molar percentages based on the sum of Zr02, Ce02 and Y203.
    Unless stated otherwise, all means are arithmetic means.
    The ratio of the average surface area of the elongated aluminous nodules to the average surface area of the grains collected, and the ratio of the number of grains collected to the number of elongated aluminous nodules are measured in an observation plane of a polished section of the sintered product, classically on electron microscopy images of this section.
    Brief Description of the Figures Other characteristics and advantages of the invention will become apparent on reading the detailed description which follows and on examining the appended drawing in which Figures 1 and 2 represent photographs of a polished section of the sintered product of Example 12, according to the invention, obtained after sintering at a temperature of 1450 ° C, the sintered product having undergone, after polishing, a thermal attack at 1400 ° C for 30 minutes to reveal the grain boundaries.
    detailed description
    To manufacture a sintered product according to the invention, one can proceed according to steps a) to c) described above and detailed below. In step a), grinding of the raw materials may be necessary to obtain a median size, after mixing, of less than 1.0 µm.
    In particular, the powders of raw materials providing the oxides can be crushed individually or, preferably, co-crushed, if they do not comply with the desired particle size distribution, and in particular if they have a median size greater than 1 μm, greater than 0, 6 µm, over 0.5 µm, over 0.3 µm or over 0.2 µm. The grinding can be carried out in a humid environment, for example in an attrition mill. After wet grinding, the ground particulate mixture is preferably dried.
    Preferably, in step a), the powders used, in particular the powders of Zr02, alumina Al203, of Y203, of Ce02, and of additive each have a median size of less than 5 μm, less than 3 μm, less than 1 µm, less than 0.7 µm, preferably less than 0.6 µm, preferably less than 0.5 µm. Advantageously, when each of these powders has a median size of less than 1 μm, preferably less than 0.8 μm, preferably less than 0.6 μm, preferably less than 0.5 μm, or even less than 0.3 pm, or even less than 0.2 pm, grinding is optional.
    The use of powders having a small median size also makes it possible, advantageously, to reduce the sintering temperature.
    These powders can also be replaced, at least partially, by powders of precursors of these oxides, introduced in equivalent amounts.
    According to the invention, the amount of cerium oxide must be between 2.5 mol% and 6.5 mol% when the amount of alumina is between 10 and 22%. When the amount of alumina is less than 10%, the amount of cerium oxide must however be greater than 2.5 mol%. The inventors have established a theoretical formula making it possible to determine a suitable minimum quantity of cerium oxide, as a function of the quantity of alumina present, namely formula (1):
    Ce02> -0.57.AI2O3 + 8.2
    Preferably, the zirconia powder used has a specific area, calculated by the BET method, greater than 5 m2 / g, preferably greater than 6 m2 / g, preferably greater than 7 m2 / g, and less than 20 m2 / g. g, preferably less than 15 m2 / g. Advantageously, the sintering temperature in step d) is reduced, and the grinding, generally in suspension, and the suspension are facilitated. The addition of CaO, and / or of an oxide of manganese, and / or of ZnO, and / or of La203, and / or of an oxide of praseodymium, and / or of SrO, and / or of a copper oxide, and / or Nd203, and / or BaO, and / or an iron oxide and / or precursors of these oxides advantageously makes it possible to increase the quantity of elongated aluminous nodules contained in the sintered product and improve mechanical performance.
    The powders providing the oxides or the precursors are preferably chosen so that the total content of impurities is less than 2%, as a percentage by weight on the basis of the oxides.
    In one embodiment, Y203 is introduced at least in part as a zirconia partially stabilized with yttrium oxide.
    In one embodiment, CeO 2 is introduced at least in part in the form of a zirconia partially stabilized with cerium oxide, or even stabilized with cerium oxide.
    As is well known to those skilled in the art, the starting charge may comprise, in addition to the particulate mixture, a solvent and / or an organic shaping additive and / or a dispersant, the natures and amounts of which are adapted to the shaping method of step b).
    Preferably the solvent is water. The organic shaping additive can be chosen from polyethylene glycol (or PEG), polyvinyl alcohols (or PVA), latexes, cellulose derivatives and mixtures thereof.
    The dispersant can be, for example, a polyacrylate.
    All these elements disappear during the subsequent manufacturing steps, although they may leave some traces. In step b), the starting charge is shaped by any technique known to those skilled in the art, preferably by strip casting or by pressing, preferably by uniaxial pressing, hot pressing or by isostatic pressing. . In the case where the starting charge is shaped by pressing, a preliminary drying step, for example by atomization, can be carried out. The size of the atomisates can for example be between 20 μm and 250 μm.
    Optionally, the shaping includes drying of the preform. In step c), the preform is sintered at a temperature above 1300 ° C, preferably above 1350 ° C, preferably above 1400 ° C, so as to obtain a sintered product according to the invention. Preferably, the sintering temperature is below 1600 ° C, preferably below 1550 ° C, preferably below 1500 ° C. The sintering is preferably carried out in air at atmospheric pressure.
    Preferably, the sintering time is greater than 1 hour, greater than 2 hours, and / or less than 10 hours, less than 7 hours, or less than 5 hours. Preferably, the sintering time is between 2 and 5 hours.
    The sintering temperature is preferably the higher the greater the amount of alumina.
    The inventors have noted the presence of a particular microstructure in the sintered products according to the invention.
    As shown in FIG. 1, the microstructure is characterized by the presence of elongated aluminous nodules 3, which may be in the form of substantially rectilinear rods. FIG. 1 also shows inclusion grains 5, in particular zirconia grains, within the elongated aluminous nodules. The average length of elongated aluminous nodules is typically greater than 1 µm and / or less than 20 µm. The microstructure specific to the products according to the invention also comprises collected grains. The collected grains typically have an average size of less than 2 µm and / or greater than 0.1 µm.
    An elongated aluminous nodule 3 can be formed by a grain, as in FIG. 1 or by a cluster of adjacent aluminous grains 11, as in FIG. 2. The aluminous grains 11 have “coalesced” during sintering. An aluminous grain preferably consists, for more than 50%, more than 60%, or even more than 70% of its mass, of Al 2 O 3 and of said additive.
    Typically, more than 90%, more than 95%, even more than 98% or 100% of the mass of the zirconia is in the form of collected grains of zirconia 7. The inventors have observed that more than 60%, preferably more than 80%, more preferably more than 90% of the volume of the zirconia is present in the tetragonal phase.
    Ce02 and Y203 serve to stabilize the zirconia but can also be present outside of it.
    Preferably, more than 90%, more than 95%, more than 98%, or even substantially 100% of the other grains collected are grains consisting for more than 40% of their mass of alumina 9.
    Analysis has shown that the elongated aluminous nodules 3 contain aluminum and the metal cations of oxides added as an additive (Ca and / or Mn and / or Zn and / or La and / or Pr and / or Sr and / or Cu and / or Nd and / or Ba and / or Fe). Said elongated aluminous nodules may also include the element Cerium (Ce). Thus, if the additive comprises CaO and a manganese oxide, said elongated aluminous nodules contain the elements Al, Ca, Mn and Ce.
    The inventors have found that the elongated aluminous nodules consist substantially, depending on the additive, of a hibonite-type phase and / or a magneto-plumbite-type phase.
    The ratio of the average surface area of the elongated aluminous nodules to the average surface area of the grains collected is preferably greater than 5, greater than 10, greater than 20, greater than 30, and / or less than 200, less than 150, less than 100 .
    The ratio of the number of grains collected to the number of elongated aluminous nodules is preferably greater than 10, greater than 20, greater than 30, greater than 40, greater than 50, and / or less than 2,000, less than 1,500, less than 1000, less than 500.
    Examples
    The following non-limiting examples are given for the purpose of illustrating the invention.
    Sintered products were prepared from: - a yttriated zirconia powder containing a molar content of Y203 equal to 3%, having a specific area of the order of 10 m2 / g and a median size of less than 0.3 pm for example 1, - of a zirconia powder of purity greater than 99%, having a specific area of the order of 10 m2 / get a median size less than 0.3 pm for example 2, - of a yttriated zirconia powder containing a molar content of Y203 equal to 1.2%, having a specific area of the order of 8 m2 / g and a median size of less than 5 μm for examples 3 to 16, - d 'a CeO 2 powder with a purity greater than 99% and having a median size less than 10 μm for Examples 2 to 16, - an alumina powder with a purity greater than 99% and having a median size less than 0, 5 μm for Examples 1 to 16, - of a powder of manganese oxides, mainly in the form Mn304 and also containing MnO, of purity, expressed as the MnO form, greater than 88%, and of which more than 90% by mass of the particles having a size less than 44 μm, for examples 3 to 16, - of a calcium carbonate powder having a median size equal to 5 pm for examples 3 to 16.
    These powders were mixed and then co-ground in a humid medium until a particulate mixture was obtained having a median particle size of less than 0.3 μm. Polyvinyl alcohol was then added in an amount equal to 2% based on the dry matter of the particulate mixture. The starting charge obtained was then atomized in the form of an atomizate powder having a median size equal to 60 μm, a relative density between 30% and 60% and a sphericity index greater than 0.85 in a spray dryer, the relative density of an atomisate powder being the ratio equal to the actual density divided by the absolute density, expressed as a percentage; the absolute density of a powder of atomisates being the ratio equal to the mass of dry matter of said powder after grinding to a fineness such that substantially no closed pore remains, divided by the volume of this mass after grinding , measured by helium pycnometry, and the actual density of a powder of atomisates being the average of the bulk densities of each atomizate of the powder, the bulk density of an atomizate being the ratio equal to the mass of said atomizate divided by the volume occupied by said atomizate. In step b), each atomizate powder was then pressed on a uni-axial press at a pressure equal to 100 MPa. In step c), the obtained preforms were then transferred to a sintering furnace where they were brought, at a speed of 100 ° C / h, up to 1450 ° C. The temperature of 1450 ° C was maintained for 2 hours. The temperature drop was carried out by natural cooling.
    Measurement protocols
    The hardness of the sintered products is measured from Vickers indentations at 0.3 kg. After measuring the length of the radial cracks, the toughness was calculated using the universal formula developed by Liang et al. (Evaluation by indentation of fracture toughness of ceramic materials, 1990).
    The 3-point flexural modulus of rupture is measured on sintered products under the conditions of ISO 6872.
    The bulk density of the sintered products is measured by hydrostatic weighing. The chemical analysis of sintered products is measured by "Inductively Coupled Plasma" or ICP for elements whose quantity does not exceed 0.5%. To determine the content of other elements, a bead of the product to be analyzed is made by melting the product, then the chemical analysis is carried out by X-ray fluorescence.
    The form factor of the grains and nodules of the sintered products, the average length of the elongated aluminous nodules and the ratio H equal to the ratio of the area covered by the elongated aluminous nodules to the area covered by said elongated aluminous nodules and the grains comprising more of 40% by mass of alumina, are measured on images obtained by backscattered electron scanning microscopy of samples of sintered products, said sections having previously been polished until a mirror quality is obtained and then thermally etched to reveal the grain boundaries, in a cycle exhibiting a temperature rise rate equal to 100 ° C / h, at a plateau temperature 50 ° C lower than the sintering temperature, maintained for 30 minutes, and a fall in temperature in natural cooling. The magnification used for taking the images is chosen so as to visualize between 2 and 4 elongated aluminous nodules on an image. 20 images per sintered product were taken.
    The average grain size of the sintered products collected was measured by the “Mean Linear Intercept” method. One such method is described in ASTM E1382. According to this standard, lines of analysis are drawn on images of the sintered products, then, along each line of analysis, the lengths, called “intercepts”, are measured between two consecutive collected grain boundaries intersecting said line d. 'analysis. The lines of analysis are determined so as not to cut an elongated aluminous nodule.
    The average length “Γ” of the intercepts “I” is then determined.
    For the tests below, the intercepts were measured on images, obtained by scanning electron microscopy, of samples of sintered products, said sections having previously been polished until a mirror quality was obtained and then thermally etched, at a temperature 50 ° C lower than the sintering temperature, to reveal the grain boundaries. The magnification used for taking the images is chosen so as to visualize approximately 100 grains picked up on an image. 5 images per sintered product were taken.
    The average grain size "d" of a sintered product is given by the relationship: d = 1.56.1 ". This formula is derived from formula (13) of “Average Grain Size in Polycrystalline Ceramics” Μ. I. Mendelson, J. Am. Cerm. Soc. Flight. 52, No. 8, pp443-446. The specific area is measured by the BET method (Brunauer Emmet Teller) as described in Journal of American Chemical Society 60 (1938), pages 309 to 316.
    Table 1 below summarizes the results obtained. (*): examples outside invention
    Table 1
    The inventors consider that there is a good compromise between hardness, toughness and 3-point flexural modulus when: the hardness is greater than or equal to 1200, and the toughness is greater than or equal to 10 MPa.m172, and the 3-point flexural modulus of rupture is greater than or equal to 700 MPa.
    Preferably, the hardness is greater than or equal to 1250, and / or the toughness is greater than or equal to 11 MPa.m172, preferably greater than or equal to 12 MPa.m1′2, preferably greater than or equal to 13 MPa.m1 / 2, preferably greater than or equal to 14 MPa.m1 / 2, and the 3-point flexural modulus of rupture is greater than or equal to 750 MPa, preferably greater than 800 MPa.
    Examples 1 and 2, outside the invention, show that a sintered product comprising a zirconia partially stabilized at 3 mol% of Y203 and an alumina content equal to 20%, and that a sintered product comprising a zirconia stabilized at 12 mol% CeO 2 and an alumina content equal to 2%, respectively, do not satisfy the desired compromise.
    A comparison of Example 3, outside the invention, and of Example 4 shows the need for an alumina content of less than 22%. This comparison also shows that for low cerium oxide contents, increasing the amount of alumina beyond 22% leads to a sudden decrease in toughness. Example 5 however shows the need for a minimum alumina content of at least 3%.
    A comparison of Example 8 outside the invention and of Example 16 in accordance with the invention shows that for the same alumina content equal to 5%, a molar CeO 2 content equal to 5.5% makes it possible to reach the compromise sought unlike a molar CeO 2 content equal to 4%. This comparison thus illustrates the need for a minimum CeO 2 content for low alumina contents, which is reflected in formula (1): CeO 2> -0.57 Al2O3 + 8.2.
    Examples 7 and 9, outside the invention, show that a molar CeO 2 content equal to 1.8% and 2% respectively is too low and does not make it possible to achieve the desired compromise.
    Examples 13 and 14, outside the invention, show that a molar CeO 2 content equal to 7.5% and 9% respectively is too high and does not make it possible to achieve the desired compromise. Examples 13 and 14 also show that, for low alumina contents according to the invention, the presence of a quantity of cerium oxide greater than 6.5 mol% leads to unsatisfactory hardness. Example 15 is everyone's favorite example. Example 15 shows that it is particularly advantageous to limit the cerium oxide content to less than 5.5%, preferably to less than 5%, to less than 4%, and even to less than 3.5%. .
    As now clearly appears, the inventors have discovered that the simultaneous presence of a low alumina content and a low cerium oxide content advantageously makes it possible to obtain a sintered product based on alumina and zirconia exhibiting a good compromise between hardness, toughness and modulus of rupture.
    Of course, the invention is not limited to the examples and embodiments described above.
    权利要求:
    Claims (14)
    [1]
    1. Sintered product exhibiting: a chemical analysis such that, in percentages by mass on the basis of the oxides, - Zr02 partially stabilized with Ce02 and Y203: complement to 100%, - Al203: 3 - 22% - additive chosen from CaO, the manganese oxides, ZnO, La203, praseodymium oxides, SrO, copper oxides, Nd203, BaO, iron oxides, and their mixtures: 0.2 - 6%, - impurities: <2%, Ce02 and Y203 being present in amounts such as, in mole percent based on the sum of Zr02, Ce02 and Y203, - Ce02: 2.5 - 6.5 mol% and - Y203: 0.5-2 mol%, provided that , if Al203 <10%, the following formula (1) is respected: Ce02> -0.57.Al2O3 + 8.2, (1) Ce02 being expressed as a molar percentage on the basis of the sum of Zr02, Ce02 and Y203 and Al 2 O 3 being expressed as a percentage by mass based on the mass of the product, a particle size distribution such as the average size of grains having an aspect ratio of less than 2.5, or "collected grains", being less at 2 μm, the average length of the elongated aluminous nodules being less than 20 μm, an elongated aluminous nodule being a structure having a form factor greater than or equal to 2.5 and consisting of an aluminous grain or of several adjacent aluminous grains, an aluminous grain being a grain consisting, for more than 40% of its mass, of Al 2 O 3 and of said additive. in Ce02 is less than 5% and greater than 3%.
    [3]
    3. Sintered product according to the immediately preceding claim, wherein said molar CeO2 content is less than 4%.
    [4]
    4. A sintered product according to any one of the preceding claims, wherein said molar content of Y203 is less than 1.7% and greater than 1%.
    [5]
    5. Sintered product according to any one of the preceding claims, in which the Al2O3 alumina content is greater than 5% and less than 19%, in percentages by weight based on the oxides.
    [6]
    6. Sintered product according to the immediately preceding claim, in which the Al 2 O 3 alumina content is greater than 8% and less than 16%, in percentages by weight based on the oxides.
    [7]
    7. Sintered product according to any one of the preceding claims, wherein the additive content is greater than 0.5% and less than 4%, in percentages by mass based on the oxides.
    [8]
    8. A sintered product according to any preceding claim, wherein the additive is a mixture of CaO on the one hand and one or more manganese oxide (s) on the other hand.
    [9]
    9. Sintered product according to the immediately preceding claim, in which the CaO content is greater than 0.2% and less than 1%, and in which the content of manganese oxide (s) expressed in the MnO form is greater than 0. , 2% and less than 1%.
    [10]
    10. Sintered product according to any one of the preceding claims, wherein the ratio of the area covered by the elongated aluminous nodules to the area covered by said elongated aluminous nodules and by the collected grains comprising more than 40% by mass of alumina. , expressed in percentages, is greater than 5% and less than 95%.
    [11]
    11. A sintered product according to any preceding claim, wherein the average length of the elongated aluminous nodules is greater than 1 µm.
    [12]
    12. Particulate mixture comprising particles of ZrO2, particles of Al2O3, particles of CeO2, particles of Y203, and particles of an additive selected from CaO, and / or particles of one or more oxide (s). manganese and / or particles of La203 and / or particles of SrO and / or particles of BaO, and / or particles of precursors of these oxides, and / or particles of several of these oxides and / or precursors of these oxides, the particulate mixture exhibiting a chemical composition suitable for the manufacture of a sintered product according to any one of the preceding claims.
    [13]
    13. Particulate mixture according to the preceding claim, comprising particles of ZrO2, particles of Al2O3, particles of CeO2, particles of Y203, particles of CaO and particles of one or more oxide (s) of manganese. , preferably particles of MnO and / or particles of Mn304, and / or particles of precursors of these oxides, and / or particles of several of these oxides and / or precursors of these oxides.
    [14]
    14. Particulate mixture according to any of the two immediately preceding claims, the median size of which is less than 1 µm.
    [15]
    15. Device chosen from: a mechanical wearing part, preferably chosen from the group formed by a shutter and a shutter seat of a valve, a pump rotor, a pump seal and a pump body, a dental article, in particular a tooth prosthesis or a part of an orthodontic appliance, an optical fiber connector, in particular a tip or a sleeve, a decorative article chosen from the group formed by a jewel, a watch, a bracelet, a necklace, a ring, a brooch, a tie pin, a purse, a telephone, a piece of furniture, a household utensil, a handle, a button, a plating, a visible part of a consumer good equipment, an eyeglass frame portion, tableware and frame, comprising a sintered product according to any one of claims 1 to 11 or made from a particulate mixture according to any one of the three immediately preceding claims.
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    同族专利:
    公开号 | 公开日
    EP3328813A1|2018-06-06|
    KR20180059428A|2018-06-04|
    CN108137414A|2018-06-08|
    JP6864668B2|2021-04-28|
    CN108137414B|2021-12-24|
    US10723657B2|2020-07-28|
    FR3039540B1|2019-12-06|
    WO2017016879A1|2017-02-02|
    JP2018531860A|2018-11-01|
    EP3328813B1|2021-09-29|
    US20180230058A1|2018-08-16|
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    WO2010140121A1|2009-06-03|2010-12-09|Saint-Gobain Centre De Recherches Et D'etudes Europeen|Alumina and zirconia sintered material|
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    JP4804943B2|2006-02-08|2011-11-02|株式会社ジーシー|Method for producing dental ceramic material|
    CN100484508C|2006-11-02|2009-05-06|温宁|Novel dental zirconium oxide prosthesis and its preparing process|FR3056208A1|2016-09-19|2018-03-23|Saint-Gobain Centre De Recherches Et D'etudes Europeen|COLORED FRITTED PRODUCT BASED ON ALUMINA AND ZIRCONIA|
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    CN113518766A|2019-03-11|2021-10-19|京瓷株式会社|Ceramic sintered body and ceramic powder|
    CN110405418B|2019-07-18|2021-07-23|广州番禺职业技术学院|Color separation craft ornament and manufacturing method thereof|
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    优先权:
    申请号 | 申请日 | 专利标题
    FR1557315A|FR3039540B1|2015-07-30|2015-07-30|ALUMINA AND ZIRCONIA-BASED FRITTED PRODUCT|
    FR1557315|2015-07-30|FR1557315A| FR3039540B1|2015-07-30|2015-07-30|ALUMINA AND ZIRCONIA-BASED FRITTED PRODUCT|
    KR1020187005595A| KR20180059428A|2015-07-30|2016-07-13|Sintered alumina-based and zirconia-based products|
    CN201680054883.1A| CN108137414B|2015-07-30|2016-07-13|Sintered product based on alumina and on zirconia|
    EP16738446.0A| EP3328813B1|2015-07-30|2016-07-13|Sintered alumina-based and zirconia-based product|
    PCT/EP2016/066697| WO2017016879A1|2015-07-30|2016-07-13|Sintered alumina-based and zirconia-based product|
    JP2018504717A| JP6864668B2|2015-07-30|2016-07-13|Sintered alumina-based and zirconia-based products|
    US15/749,034| US10723657B2|2015-07-30|2016-07-13|Sintered alumina-based and zirconia-based product|
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