Zirconia composite ceramic and preparation method and application thereof

Abstract

This application provides zirconia composite ceramics, their preparation methods, and applications, comprising the following phases by weight percentage: 92 wt.%–99 wt.% yttrium-stabilized tetragonal zirconia and 1 wt.%–8 wt.% titanium-based composite oxide; wherein the general molecular formula of the titanium-based composite oxide includes Ti. (1‑x‑y) M x A y O (2‑x‑0.5y) x = 0 or 0.01 ≤ x ≤ 0.1, y = 0 or 0.01 ≤ y ≤ 0.1, and x and y are not both 0. This zirconia composite ceramic has high color purity, strong visual impact, and excellent drop resistance, making it suitable for providing highly recognizable electronic device housing components.

Description

Technical Field

[0001] This application relates to the field of inorganic non-metallic materials technology, specifically to zirconia composite ceramics and their preparation methods and applications. Background Technology

[0002] Zirconia ceramics are widely used due to their high strength, high hardness, and excellent corrosion resistance. Especially in the era of explosive growth in electronic device users, mobile phones and smart wearable devices with zirconia ceramic casings are gaining increasing popularity, with black zirconia ceramic casings being particularly sought after. However, the industry generally prepares black zirconia ceramics by introducing colored oxides such as cobalt oxide into the zirconia ceramic or simply adding titanium dioxide. The black zirconia ceramics produced by these methods either lack sufficient color purity or are too expensive. Therefore, there is an urgent need to develop a black zirconia ceramic with high color purity, good mechanical properties, and low production cost. Summary of the Invention

[0003] In view of this, this application provides a zirconia composite ceramic and a method for preparing the same. The zirconia composite ceramic has high color purity, strong visual impact, and excellent drop resistance, and can be used to provide electronic device housing components with highly recognizable appearance.

[0004] The first aspect of this application provides a zirconia composite ceramic, wherein the zirconia composite ceramic comprises the following phases by weight percentage: 92 wt.%-99 wt.% yttrium-stabilized tetragonal zirconia and 1 wt.%-8 wt.% titanium-based composite oxide; wherein the general molecular formula of the titanium-based composite oxide includes Ti. (1-x-y) M x A y O (2-x-0.5y) x = 0 or 0.01 ≤ x ≤ 0.1, y = 0 or 0.01 ≤ y ≤ 0.1, x and y are not both 0; element M includes at least one of Co, Ni, Mn, Zn, Mg, Sr, Ba and Ca; element A includes at least one of Cr, Fe, Al, La, Er, Nd and Yb.

[0005] Titanium-based composite oxide Ti (1-x-y) M x A y O (2-x-0.5y)The color is black with high purity, resulting in a purer and deeper black color in the composite zirconia ceramic. Simultaneously, the presence of the aforementioned titanium-based composite oxide allows yttrium-stabilized tetragonal zirconia to form oxygen vacancies during sintering, increasing the activity of the tetragonal phase in the composite zirconia ceramic and thus improving its impact resistance. Therefore, the aforementioned zirconia composite ceramic exhibits high color purity, strong visual impact, and excellent drop resistance, making it suitable for providing highly visually distinctive electronic device housing components.

[0006] The second aspect of this application provides a method for preparing zirconia composite ceramics, comprising the following steps:

[0007] (1) A mixture of M element source and / or A element source and titanium dioxide is subjected to a first sintering treatment to obtain a composite oxide raw material; wherein, the general molecular formula of the composite oxide raw material includes Ti (1-x’-y’) M x’ A y’ O (2-x’-0.5y’) x' = 0 or 0.01 ≤ x' ≤ 0.1, y' = 0 or 0.01 ≤ y' ≤ 0.1, and x' and y' are not both 0; the M element includes at least one of Co, Ni, Mn, Zn, Mg, Sr, Ba and Ca; the A element includes at least one of Cr, Fe, Al, La, Er, Nd and Yb;

[0008] (2) After mixing yttrium-stabilized tetragonal zirconium oxide and the composite oxide raw material, the mixture is sintered once, cooled, and then crushed and refined in sequence to obtain the precursor material.

[0009] (3) The precursor material is subjected to granulation, pressing, second sintering, and reduction sintering treatments in sequence to obtain zirconia composite ceramic; wherein the zirconia composite ceramic comprises the following phases by weight percentage: 92wt.%-99wt.% yttrium-stabilized tetragonal zirconia and 1wt.%-8wt.% titanium-based composite oxide; wherein the general molecular formula of the titanium-based composite oxide includes Ti (1-x-y) M x A y O (2-x-0.5y) x = 0 or 0.01 ≤ x ≤ 0.1, y = 0 or 0.01 ≤ y ≤ 0.1, and x and y are not both 0.

[0010] The above preparation method is simple, efficient, and low-cost, and can be used for large-scale industrial production.

[0011] The third aspect of this application provides a cover plate, including the zirconia composite ceramic provided in the first aspect of this application or the zirconia composite ceramic prepared according to the preparation method provided in the second aspect of this application.

[0012] The aforementioned cover plate, due to the presence of the zirconia composite ceramic provided in this application, possesses a high-purity black appearance and exhibits high strength and good drop resistance, thus balancing aesthetics and mechanical properties. Therefore, it can be used to provide an electronic device with a pure black ceramic appearance, which can significantly improve the recognizability and market competitiveness of the electronic device.

[0013] The fourth aspect of this application provides an electronic device that includes the cover provided in the third aspect of this application. Because of the aforementioned cover, this electronic device has high visual distinctiveness and strong market competitiveness. Detailed Implementation

[0014] Specifically, this application provides a zirconia composite ceramic comprising the following phases by weight percentage: 92 wt.%-99 wt.% yttrium-stabilized tetragonal zirconia and 1 wt.%-8 wt.% titanium-based composite oxide; wherein the general molecular formula of the titanium-based composite oxide includes Ti. (1-x-y) M x A y O (2-x-0.5y) x = 0 or 0.01 ≤ x ≤ 0.1, y = 0 or 0.01 ≤ y ≤ 0.1, x and y are not both 0; the M element includes, but is not limited to, at least one of Co, Ni, Mn, Zn, Mg, Sr, Ba and Ca; the A element includes, but is not limited to, at least one of Cr, Fe, Al, La, Er, Nd and Yb.

[0015] The above-mentioned titanium-based composite oxide Ti (1-x-y) M x A y O (2-x-0.5y) It is made from composite oxide raw material Ti (1-x’-y’) M x’ A y’ O (2-x’-0.5y’) The black substance formed by reduction sintering after mixing with yttrium-stabilized tetragonal zirconium oxide, and Ti (1-x’-y’) M x’ A y’ O (2-x’-0.5y’) It is a light-colored substance formed by sintering divalent metal compounds (e.g., MO) and / or trivalent metal compounds (e.g., A₂O₃) with TiO₂. During the reduction sintering process, the M and / or A elements in the composite oxide raw material have a very strong oxidation tendency, which will steal oxygen atoms from titanium dioxide and thus force TiO₂ to oxidize. 4+ Fully reduce to form Ti n+ (1≤n<4), forming a black titanium-based composite oxide Ti (1-x-y) M x A y O (2-x-0.5y)This results in a purer and deeper black color in the composite zirconia ceramic. At the same time, the oxidation tendency of the M and A elements can also remove oxygen atoms from the yttrium-stabilized tetragonal zirconia to form oxygen vacancies, causing lattice distortion in the yttrium-stabilized tetragonal zirconia and thus enhancing the tetragonal phase activity, thereby improving the impact resistance of the zirconia composite ceramic.

[0016] In this application, the general molecular formula of the aforementioned composite oxide raw material can be Ti. (1-x’-y’) M x’ A y’ O (2-x’-0.5y’) The corresponding titanium-based composite oxide is Ti (1-x-y) M x A y O (2-x-0.5y) The composite oxide raw material can also be simply Ti. (1-x’) M x’ O (2-0.5y’) The corresponding titanium-based composite oxide is Ti (1-x) M x O (2-x) Composite oxide raw materials can also be used solely for Ti (1-y’) M x’ A y’ O (2-0.5y’) The corresponding titanium-based composite oxide is Ti (1-y) A y O (2-0.5y) It should be noted that, for a specific embodiment, the general molecular formula of the composite oxide raw material used in the preparation process is formally consistent with the general molecular formula of the titanium-based composite oxide in the final material. For example, in a specific embodiment, the composite oxide added during the preparation process is Ti. 0.95 Cr 0.05 O 1.975 Finally, the general molecular formula of the titanium-based composite oxide in the zirconia composite ceramic is also Ti. 0.95 Cr 0.05 O 1.975 However, the oxidation state of Ti is different in the two substances, and the oxidation state of Cr also changes accordingly. For example, the value of x can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, etc. For example, the value of y can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, etc.

[0017] In this application, by way of example, the weight percentage of yttrium-stabilized tetragonal zirconium oxide can be 92 wt.%, 92.5 wt.%, 93 wt.%, 93.5 wt.%, 94 wt.%, 94.5 wt.%, 95 wt.%, 95.5 wt.%, 96 wt.%, 96.5 wt.%, 97 wt.%, 97.5 wt.%, 98 wt.%, 98.5 wt.%, 99 wt.%, etc. Correspondingly, the mass percentage of titanium-based composite oxide can be 8 wt.%, 7.5 wt.%, 7 wt.%, 6.5 wt.%, 6 wt.%, 5.5 wt.%, 5 wt.%, 4.5 wt.%, 4 wt.%, 3.5 wt.%, 3 wt.%, 2.5 wt.%, 2 wt.%, 1.5 wt.%, 1 wt.%, etc. In this application, the mass content of each phase was determined by X-ray diffraction (XRD). Excessive titanium-based composite oxide content in zirconia composite ceramic materials severely affects the material's strength and hardness, hindering its application; conversely, insufficient titanium-based composite oxide content results in a less deep color in the zirconia composite ceramic, failing to meet usage requirements.

[0018] In this application, the zirconia composite ceramic material may also contain a small amount of monoclinic zirconia. In some specific embodiments, the content of monoclinic zirconia is 0.1 wt.%-0.3 wt.%.

[0019] In some embodiments of this application, the molar content of yttrium in the yttrium-stabilized tetragonal zirconia is 1.5 mol% to 4 mol%. Exemplarily, the molar content of yttrium in the yttrium-stabilized tetragonal zirconia can be 1.5 mol%, 22.5 mol%, 3 mol%, 3.5 mol%, 4 mol%, etc. Controlling the yttrium content within the above range is beneficial for ensuring good mechanical properties of the zirconia composite ceramic.

[0020] In some embodiments of this application, the zirconia composite ceramic, based on phase composition, comprises 93 wt.%-98 wt.% yttrium-stabilized tetragonal zirconia and 2 wt.%-7 wt.% titanium-based composite oxide. In this case, the zirconia composite ceramic exhibits superior impact resistance and overall performance while possessing a high-purity black appearance.

[0021] In some embodiments of this application, the zirconia composite ceramic comprises, by mass percentage, the following elements: 63.38 wt%-71.38 wt% zirconium, 1.88 wt%-5.41 wt% yttrium, 0.54 wt%-4.75 wt% titanium, 0.006 wt%-0.59 wt% a first element, and oxygen; wherein the first element comprises at least one of the M element and the A element.

[0022] For example, the mass percentage of zirconium can be 63.38 wt%, 64 wt%, 64.5 wt%, 65 wt%, 65.5 wt%, 66 wt%, 66.5 wt%, 67 wt%, 67.5 wt%, 68 wt%, 68.8 wt%, 69 wt%, 69.5 wt%, 70 wt%, 70.5 wt%, 71 wt%, 71.15 wt%, 71.2 wt%, 71.25 wt%, 71.3 wt%, 71.31 wt%, 71.32 wt%, 71.33 wt%, 71.34 wt%, 71.35 wt%, 71.36 wt%, 71.38 wt%, etc. The mass percentage of yttrium can be 1.88 wt%, 1.89 wt%, 1.9 wt%, 2.0 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 4.5 wt%, 5.0 wt%, 5.1 wt%, 5.2 wt%, 5.3 wt%, 5.4 wt%, 5.41 wt%, etc. For example, the mass percentage can be 0.54 wt%, 0.55 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 1.0 wt%, 1.5 wt%, 2.0 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 4.5 wt%, 4.6 wt%, 4.7 wt%, 4.72 wt%, 4.75 wt%, etc. For example, the mass percentage of the first element can be 0.006 wt%, 0.007 wt%, 0.008 wt%, 0.009 wt%, 0.01 wt%, 0.02 wt%, 0.03 wt%, 0.04 wt%, 0.05 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.45 wt%, 0.5 wt%, 0.55 wt%, 0.6 wt%, 0.57 wt%, 0.58 wt%, 0.59 wt%, etc. The mass percentage content of elements in the zirconia composite ceramic described in this application can be determined, but is not limited to, by X-ray fluorescence spectroscopy (XRF) analysis.

[0023] In some embodiments of this application, the zirconia composite ceramic comprises, by mass percentage, the following elements: 64.06 wt%-70.65 wt% zirconium, 1.91 wt%-5.36 wt% yttrium, 1.08 wt%-4.16 wt% titanium, 0.012 wt%-0.52 wt% a first element, and oxygen; wherein the first element comprises at least one of the M element and the A element.

[0024] In some embodiments of this application, the color of the above-mentioned zirconia composite ceramic has an L value between 6.51 and 7.35, an a value between 0.04 and 0.23, and a b value between -0.29 and -0.10. Exemplarily, the L value can be 6.51, 6.55, 6.6, 6.65, 6.7, 6.8, 6.9, 7, 7.1, 7.2, 7.25, 7.3, 7.35, etc. Exemplarily, the a value can be 0.04, 0.05, 0.1, 0.15, 0.2, 0.21, 0.22, 0.23, etc. Exemplarily, the b value can be -0.29, -0.25, -0.23, -0.2, -0.15, -0.12, -0.10, etc. Here, the L, a, and b values ​​correspond to L, a, and b in the Lab values ​​(or Lab color values), respectively; where L is the luminance channel, and a and b are the two color channels; the closer the a and b values ​​are to 0, the higher the purity of the black in the material. The Lab values ​​are based on the Lab color model. The Lab values ​​can be obtained by testing with a colorimeter. The zirconia composite ceramic provided in this application has high black purity, deep color, high luster, and excellent appearance.

[0025] In this application, the Vickers hardness of the zirconia composite ceramic is greater than or equal to 1260 Hv. In some specific embodiments, the Vickers hardness of the zirconia composite ceramic is in the range of 1290 Hv-1340 Hv. For example, the Vickers hardness of the zirconia composite ceramic of this application can be 1260 Hv, 1265 Hv, 1270 Hv, 1275 Hv, 1280 Hv, 1285 Hv, 1290 Hv, 1295 Hv, 1299 Hv, 1300 Hv, 1305 Hv, 1310 Hv, 1315 Hv, 1320 Hv, 1325 Hv, 1330 Hv, 1335 Hv, 1340 Hv, etc. Such high hardness ensures the impact resistance of the zirconia composite ceramic (e.g., strong resistance to drop hammer impact), thereby providing a drop-resistant cover plate with pure color and strong protective force. In this embodiment, a 60g drop hammer is used to perform a drop hammer test on the above-mentioned zirconia composite ceramic, and the average drop hammer height is greater than or equal to 25cm. In some specific embodiments, the average drop hammer height is 29cm-31cm.

[0026] This application also provides a method for preparing zirconia composite ceramics, which can be used to prepare the zirconia composite ceramics provided in this application, including the following steps:

[0027] (1) A mixture of M element source and / or A element source and titanium dioxide is subjected to a first sintering treatment to obtain a composite oxide raw material; wherein, the general molecular formula of the composite oxide raw material includes Ti (1-x’-y’) M x’ A y’O (2-x’-0.5y’) x' = 0 or 0.01 ≤ x' ≤ 0.1, y' = 0 or 0.01 ≤ y' ≤ 0.1, and x' and y' are not both 0; the M element includes at least one of Co, Ni, Mn, Zn, Mg, Sr, Ba and Ca; the A element includes at least one of Cr, Fe, Al, La, Er, Nd and Yb;

[0028] (2) After mixing yttrium-stabilized tetragonal zirconium oxide and the composite oxide raw material, the mixture is sintered once, cooled, and then crushed and refined in sequence to obtain the precursor material.

[0029] (3) The precursor material is subjected to granulation, pressing, second sintering, and reduction sintering treatments in sequence to obtain zirconia composite ceramic; wherein the zirconia composite ceramic comprises the following phases by weight percentage: 92wt.%-99wt.% yttrium-stabilized tetragonal zirconia and 1wt.%-8wt.% titanium-based composite oxide; wherein the general molecular formula of the titanium-based composite oxide includes Ti (1-x-y) M x A y O (2-x-0.5y) x = 0 or 0.01 ≤ x ≤ 0.1, y = 0 or 0.01 ≤ y ≤ 0.1, and x and y are not both 0.

[0030] First, the M element source and / or A element source are sintered with titanium dioxide to form a composite oxide raw material, Ti 4+ With M 2+ A 3+ The stronger atomic forces between them can significantly improve the performance of Ti. 4+ The degree of reduction during reduction sintering forces oxygen atoms from titanium dioxide, thereby compelling Ti... 4+ Fully reduce to form Ti n+ (1≤n<4), forming a black titanium-based composite oxide Ti (1-x-y) M x A y O (2-x-0.5y) This allows for the production of zirconia composite ceramics with a purer and deeper black color. Furthermore, the reducing power of the M and / or A elements in the composite oxide raw material can also capture oxygen vacancies in zirconia, resulting in a zirconia composite ceramic that simultaneously possesses strong impact resistance and a pure black color.

[0031] Traditional production processes typically involve mixing black coloring powder into zirconium oxide powder. This process renders the powder-making equipment used for mixing unusable for producing powders of other colors, resulting in low equipment utilization and excessively high material production costs. The preparation method provided in this application effectively solves these problems and significantly reduces material production costs.

[0032] In some embodiments of this application, in step (1), the source of element M includes, but is not limited to, oxides of element M (where element M is divalent); for example, CoO, NiO, MnO, etc. In some embodiments of this application, the median particle size of the source of element M is 0.15 μm-0.6 μm. Exemplarily, the median particle size of the source of element M can be 0.15 μm, 0.2 μm, 0.25 μm, 0.3 μm, 0.35 μm, 0.4 μm, 0.45 μm, 0.5 μm, 0.55 μm, 0.6 μm, etc. The source of element A includes, but is not limited to, oxides of element A (where element A is trivalent); for example, Cr2O3, Fe2O3, etc. The median particle size of the source of element A is 0.2 μm-0.5 μm. For example, the median particle size of element A source can be 0.2 μm, 0.25 μm, 0.3 μm, 0.35 μm, 0.4 μm, 0.45 μm, 0.5 μm, etc. In some embodiments of this application, in step (1), the median particle size of titanium dioxide is 0.2 μm. In some embodiments of this application, in step (2), the median particle size of yttrium-stabilized tetragonal zirconium oxide is 0.3 μm-0.6 μm.

[0033] By controlling the median particle size of the above materials to the nanoscale, the raw materials can be fully mixed, thereby ensuring that the final zirconia composite ceramic material has uniform color and good mechanical properties.

[0034] In some embodiments of this application, the mixing process in step (1) may specifically include: adding M element source and / or A element source and titanium dioxide to a ball milling jar in proportion, adding solvent for ball milling, and the ball milling time may be 8 hours; then transferring to an oven for drying to obtain dry powder.

[0035] In some embodiments of this application, in step (1), the temperature of the first sintering treatment is 1100℃-1300℃, and the time is 1h-3h. Exemplarily, the temperature of the first sintering treatment can be 1100℃, 1150℃, 1200℃, 1250℃, 1300℃, etc. Exemplarily, the holding time can be 1h, 1.5h, 2h, 2.5h, 3h, etc. After the first sintering treatment, a composite oxide raw material powder is obtained. The composite oxide raw material powder is then subjected to particle size refinement treatment, which can be achieved by transferring it to a sand mill and sand milling it together with a solvent for 8h-12h, followed by spray drying for later use. The solvent includes, but is not limited to, deionized water.

[0036] In some embodiments of this application, step (2) of the mixing process may specifically include: adding the composite oxide raw material powder and yttrium-stabilized tetragonal zirconium oxide together into a ball mill, adding solvent for ball milling, and the ball milling time can be 7h-10h; then transferring it to a sand mill, adding dispersant and solvent and sand milling together for 8h-12h, finally adding a suitable proportion of binder (e.g., polyvinyl alcohol, polyethylene glycol 4000, etc., the mass of the binder accounting for 1%-3% of the total mass of the mixed raw materials), and stirring for 2h-4h to obtain a slurry. The solvent includes, but is not limited to, deionized water.

[0037] In this application, the lining and grinding balls of the ball milling and sand milling equipment are all made of zirconia ceramic, which can avoid the introduction of impurities.

[0038] In some embodiments of this application, in step (3), spray drying can be used to dry and granulate the above slurry to obtain the precursor material.

[0039] In some embodiments of this application, the molding process in step (3) may include, but is not limited to, dry pressing, isostatic pressing, injection molding, or hot die casting. For example, the dry pressing process includes, but is not limited to, using a 200t press with a hydraulic pressure of 8MPa. Of course, the molding process can also be achieved through other molding processes.

[0040] In some embodiments of this application, in step (3), the holding temperature of the second sintering treatment is 1400℃-1600℃, the holding time is 1h-2h, and the atmosphere is air. Specifically, the heating program of the second sintering treatment can be as follows: heating from room temperature to 500℃-700℃ within 300min-500min, holding for 1h-3h; then heating to 1050℃-1250℃ within 200min-400min, holding for 1-3h; immediately following, heating to 1050℃-1250℃ within 100min-200min, holding for 1-3h; finally, heating to the aforementioned holding temperature (1400℃-1600℃) within 40min-60min, holding for 1h-2h, and then starting to cool down. The cooling program includes: cooling from the aforementioned holding temperature to 800℃-1000℃ within 100min-200min, and then naturally cooling to room temperature.

[0041] In some embodiments of this application, the conditions for the reduction sintering treatment in step (3) are as follows: the temperature is raised to 1150℃-1250℃ in a vacuum furnace and held for 1-3 hours, then cooled to room temperature in a hydrogen atmosphere. Exemplarily, the holding temperature can be 1150℃, 1175℃, 1200℃, 1225℃, 1250℃, etc. Exemplarily, the holding time can be 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, etc. In some specific embodiments, the heating rate is 1.5℃ / min-3.5℃ / min. Exemplarily, the heating rate can be 1.5℃ / min, 2℃ / min, 3℃ / min, 3.5℃ / min, etc.

[0042] In some embodiments of this application, step (4) is also included: polishing, cutting and other finishing processes are performed on the obtained zirconia composite ceramic.

[0043] This application does not impose any restrictions on the specific heating procedures, sand milling and ball milling procedures, spray drying and granulation procedures involved in the sintering treatment in the aforementioned steps (1)-(3). Those skilled in the art can adjust and adapt them according to the actual production situation.

[0044] This application also provides a cover plate, comprising the zirconia composite ceramic provided in this application or the zirconia composite ceramic prepared according to the preparation method of this application. Because the cover plate incorporates the zirconia composite ceramic provided in this application, it possesses a high-purity black appearance and exhibits high strength and good drop resistance, thus balancing aesthetics and mechanical properties. Therefore, it can be used to provide an electronic device with a pure black ceramic appearance, significantly improving the recognizability and market competitiveness of the electronic device.

[0045] This application also provides an electronic device, including the cover plate provided in this application. Because of the cover plate, this electronic device has high visual distinctiveness and strong market competitiveness. The aforementioned electronic device includes, but is not limited to, mobile phones, tablets, laptops, smartwatches, and electronic cigarettes. For example, the cover plate can be processed into the casing of mobile phones, tablets, laptops, and smartwatches, and can also be processed into relevant parts of electronic cigarettes, giving the aforementioned electronic devices a cool appearance and enhancing their visual appeal and product competitiveness.

[0046] In addition, the aforementioned zirconia composite ceramics can also be processed into luxury brand nameplates, which can further enhance the artistic appeal of the products.

[0047] The technical solution of this application will be described in detail below with several embodiments.

[0048] Example 1

[0049] (1) Cobalt oxide and titanium dioxide were mixed and sintered at 1200℃ for 2 hours (first sintering treatment) to obtain composite oxide powder Ti. 0.95 Co 0.05 O 1.95 .

[0050] (2) Mix 3 mol% yttrium-stabilized tetragonal zirconium oxide powder and the above composite oxide powder at a mass ratio of 95:5, add them to a ball mill jar, add water and ball mill for 8 hours, then transfer them to a sand mill, add 0.02 wt% hydroxypropyl methylcellulose and water and sand mill for 10 hours, finally add 4 wt.% of the above powder mass and binder (polyethylene glycol 4000 and polyvinyl alcohol in a molar ratio of 1:1) and stir for 0.5 hours to form a spray slurry with a solid content of 25 wt%.

[0051] (3) The spray slurry is fed into the spray tower for spray drying (inlet air temperature is 250℃, outlet air temperature is 110℃, centrifugal speed is 15 rpm) to form a spherical powder with strong fluidity; the spherical powder is transferred to the press for dry pressing (using a 200t press, with the hydraulic pressure set to 8MPa) to obtain the blank;

[0052] The blank was subjected to a second sintering treatment according to the following procedure: the temperature was raised from room temperature to 600℃ in 400 minutes and held for 2 hours, then raised from 600℃ to 1250℃ in 300 minutes and held for 2 hours, then raised from 1150℃ to 1450℃ in 150 minutes and held for 2 hours, then cooled to 900℃ in 150 minutes, and finally cooled naturally to room temperature to obtain the ceramic part.

[0053] The ceramic parts were transferred to a vacuum furnace and heated from room temperature to 1200℃ at a rate of 3℃ / min under a hydrogen atmosphere, and held for 2 hours. After cooling to room temperature in the furnace, black zirconia composite ceramics were obtained. The zirconia composite ceramics were then ground, polished, and laser-cut to obtain zirconia composite ceramic samples with dimensions of 150mm × 75mm × 0.6mm.

[0054] Example 2

[0055] The only difference from Example 1 is that in step (2), 3 mol% yttrium-stabilized tetragonal zirconium oxide powder and the above-mentioned composite oxide powder Ti are added. 0.95 Co 0.05 O 1.95 Mix at a mass ratio of 97:3.

[0056] Example 3

[0057] The only difference from Example 1 is that in step (2), 3 mol% yttrium-stabilized tetragonal zirconium oxide powder and the above-mentioned composite oxide powder Ti are added. 0.95 Co0.05 O 1.95 Mix at a mass ratio of 96:4.

[0058] Example 4

[0059] The only difference from Example 1 is that in step (1), chromium oxide and titanium dioxide are mixed and sintered at 1200°C for 2 hours (first sintering treatment) to obtain composite oxide powder Ti. 0.95 Cr 0.05 O 1.975 .

[0060] In step (2), 3 mol% yttrium-stabilized tetragonal zirconium oxide powder and the above-mentioned composite oxide powder Ti are added. 0.95 Cr 0.05 O 1.975 Mix at a mass ratio of 95:5.

[0061] Example 5

[0062] The only difference from Example 4 is that in step (2), 3 mol% yttrium-stabilized tetragonal zirconium oxide powder and the above-mentioned composite oxide powder Ti are added. 0.95 Cr 0.05 O 1.975 Mix at a mass ratio of 97:3.

[0063] Example 6

[0064] The only difference from Example 4 is that in step (2), 3 mol% yttrium-stabilized tetragonal zirconium oxide powder and the above-mentioned composite oxide powder Ti are added. 0.95 Cr 0.05 O 1.975 Mix at a mass ratio of 96:4.

[0065] Example 7

[0066] The only difference from Example 4 is that in step (2), 3 mol% yttrium-stabilized tetragonal zirconium oxide powder and the above-mentioned composite oxide powder Ti are added. 0.95 Cr 0.05 O 1.975 Mix at a mass ratio of 99:1.

[0067] Example 8

[0068] The only difference from Example 4 is that in step (2), 3 mol% yttrium-stabilized tetragonal zirconium oxide powder and the above-mentioned composite oxide powder Ti are added. 0.95 Cr 0.05 O 1.975 Mix at a mass ratio of 92:8.

[0069] To highlight the beneficial effects of the embodiments of this application, the following comparative examples are provided.

[0070] Comparative Example 1

[0071] The only difference from Example 1 is that in step (3), the zirconia composite ceramic is obtained after the second sintering treatment without reduction sintering.

[0072] Comparative Example 2

[0073] The difference from Example 1 is only that: (1) 3 mol% yttrium-stabilized tetragonal zirconium oxide powder and titanium dioxide powder are mixed at a mass ratio of 95:5, added to a ball mill jar and ball-milled with water for 8 hours, then transferred to a sand mill and added 0.02 wt% hydroxypropyl methylcellulose and water and sand-milled for 10 hours. Finally, 4 wt.% of the above powder mass and binder (polyethylene glycol 4000 and polyvinyl alcohol with a molar ratio of 1:1) are added and stirred for 0.5 hours to form a spray slurry with a solid content of 25 wt%.

[0074] Step (2) is the same as step (3) in Example 1.

[0075] Comparative Example 3

[0076] The difference from Example 1 is only that: (1) 3 mol% yttrium-stabilized tetragonal zirconium oxide powder, titanium dioxide powder and cobalt oxide are mixed in a mass ratio of 95:4.76:0.235, added to a ball mill jar and ball-milled with water for 8 hours, then transferred to a sand mill and added 0.02 wt% hydroxypropyl methylcellulose and water and sand-milled for 10 hours, and finally added 4 wt.% of the above powder mass and binder (polyethylene glycol 4000 and polyvinyl alcohol in a molar ratio of 1:1) and stirred for 0.5 hours to form a spray slurry with a solid content of 25 wt%.

[0077] Step (2) is the same as step (3) in Example 1.

[0078] Comparative Example 4

[0079] The only difference from Example 4 is that in step (2), 3 mol% yttrium-stabilized tetragonal zirconium oxide powder and the above-mentioned composite oxide powder Ti are added. 0.95 Cr 0.05 O 1.975 Mix at a mass ratio of 90:10.

[0080] Characterization test

[0081] (1) XRD tests were performed on the composite zirconia ceramics prepared in each example and comparative example to determine the mass percentage of each phase. The results are summarized in Table 1.

[0082] (2) XRF tests were performed on the composite zirconia ceramics prepared in each embodiment and comparative example to determine the molar percentage of each element. The results are summarized in Table 1.

[0083] (3) Hardness test: The hardness of the zirconia composite ceramic samples prepared in each example and comparative example was tested using a hardness tester and indentation method (diamond indenter, force 10kg, test time 15s). The results are summarized in Table 2.

[0084] (4) Density test: Observe the average number of pits (greater than 20 μm) within a 10 mm × 10 mm area on the surface of each zirconia composite ceramic sample after polishing. The results are summarized in Table 2.

[0085] (5) Drop hammer impact test: A drop hammer impact tester was used. Each composite zirconia ceramic sample (150×75×0.6mm) was placed on a platform, and a 60g drop hammer was used to strike the geometric center of the sample. The drop height started from 5cm. If no crack appeared after the impact, the drop height was increased by 5cm and the test continued until a crack appeared. The drop height at which the crack appeared was recorded. Ten samples were selected for each example and the average drop height was calculated. The results are summarized in Table 2.

[0086] (6) The Lab values ​​of each composite zirconia ceramic sample were measured using an Xrite Ci60 colorimeter. L represents the luminance channel, and a and b represent the two color channels. The results are summarized in Table 2.

[0087] Table 1. Phase composition and elemental composition of composite zirconia ceramics prepared in each embodiment and comparative example.

[0088]

[0089] Table 2 Performance parameters of composite zirconia ceramics prepared in each embodiment and comparative example

[0090]

[0091] As can be seen from the data in Tables 1 and 2, the zirconia composite ceramics prepared in the embodiments of this application not only have a pure and deep black appearance, but also good impact resistance. However, in Comparative Example 1, because reduction sintering was not performed, the Ti ions in the finished product remained at +4 valence, failing to produce a blackening effect. Comparative Example 2 added titanium dioxide to the raw materials, resulting in a higher L value and higher absolute values ​​of a and b, significantly insufficient purity of black. Comparative Example 3 added titanium dioxide and cobalt oxide to the raw materials; although the content of each element was similar to that of this application, the purity of black was poor, and its mechanical properties were far inferior to the embodiments. The zirconia composite ceramics prepared in Comparative Example 4 had an excessively high content of titanium-based composite oxides; although the final material still had a black appearance, its mechanical properties were insufficient, and this zirconia composite ceramic could not simultaneously meet the requirements of appearance and performance. A review of the data from the embodiments reveals that when the percentage of phase mass and the percentage of element mass are within the preferred range defined in this application, the overall performance of the zirconia composite ceramic is superior.

[0092] The above description is an exemplary embodiment of this application. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principles of this application, and these improvements and modifications are also considered to be within the scope of protection of this application.

Claims

1. A zirconia composite ceramic, characterized in that, The zirconia composite ceramic comprises the following phases by weight percentage: 93 wt.%-98 wt.% yttrium-stabilized tetragonal zirconia and 2 wt.%-7 wt.% titanium-based composite oxide; wherein the general molecular formula of the titanium-based composite oxide includes Ti. (1-x-y) M x A y O (2-x-0.5y) Where x = 0 or 0.01 ≤ x ≤ 0.1, y = 0 or 0.01 ≤ y ≤ 0.1, and x and y are not both 0; element M includes at least one of Co, Ni, and Mn; element A includes at least one of Cr and Al.

2. The zirconia composite ceramic according to claim 1, characterized in that, The color of the zirconia composite ceramic has an L value between 6.51 and 7.35, an a value between 0.04 and 0.23, and a b value between -0.29 and -0.

10.

3. The zirconia composite ceramic according to claim 1, characterized in that, The zirconia composite ceramic has a Vickers hardness greater than or equal to 1260 Hv.

4. The zirconia composite ceramic according to claim 1, characterized in that, The molar content of yttrium in the yttrium-stabilized tetragonal zirconium oxide is 1.5 mol%-4 mol.

5. The zirconia composite ceramic according to claim 1, characterized in that, The zirconia composite ceramic comprises the following elements by mass percentage: The mixture comprises 63.38wt%-71.38wt% of zirconium, 1.88wt%-5.41wt% of yttrium, 0.54wt%-4.75wt% of titanium, 0.006wt%-0.59wt% of a first element, and oxygen; wherein the first element includes at least one of the elements M and A.

6. The zirconia composite ceramic according to claim 1, characterized in that, The zirconia composite ceramic comprises the following elements in weight percentages: 64.06wt%-70.65wt% zirconium, 1.91wt%-5.36wt% yttrium, 1.08wt%-4.16wt% titanium, 0.012wt%-0.52wt% of a first element, and oxygen; wherein the first element comprises at least one of the elements M and A.

7. A method for preparing zirconia composite ceramics, characterized in that, Includes the following steps: (1) A mixture of M element source and / or A element source and titanium dioxide is subjected to a first sintering treatment to obtain a composite oxide raw material; wherein the general molecular formula of the composite oxide raw material includes Ti (1-x’-y’) M x’ A y’ O (2-x’-0.5y’) x' = 0 or 0.01 ≤ x' ≤ 0.1, y' = 0 or 0.01 ≤ y' ≤ 0.1, and x' and y' are not both 0; the M element includes at least one of Co, Ni, and Mn; the A element includes at least one of Cr and Al; (2) After mixing yttrium-stabilized tetragonal zirconium oxide and the composite oxide raw material, the mixture is sintered once, cooled, and then crushed and fined in sequence to obtain the precursor material; (3) The precursor material is subjected to granulation, pressing, second sintering, and reduction sintering treatments in sequence to obtain zirconia composite ceramic; wherein the zirconia composite ceramic comprises the following phases by weight percentage: 93wt.%-98wt.% yttrium-stabilized tetragonal zirconia and 2wt.%-7wt.% titanium-based composite oxide; wherein the general molecular formula of the titanium-based composite oxide includes Ti (1-x-y) M x A y O (2-x-0.5y) x = 0 or 0.01 ≤ x ≤ 0.1, y = 0 or 0.01 ≤ y ≤ 0.1, and x and y are not both 0.

8. The preparation method according to claim 7, characterized in that, The temperature of the first sintering treatment is 1100℃-1300℃, and the time is 1 h-3 h.

9. The preparation method according to claim 7, characterized in that, The conditions for reduction sintering are: holding at 1150 ℃-1250 ℃ for 1 h-3 h in a hydrogen atmosphere.

10. A cover plate, characterized in that, The cover plate comprises zirconia composite ceramic as described in any one of claims 1-6 or zirconia composite ceramic prepared by the preparation method described in any one of claims 7-9.

11. An electronic device, characterized in that, The electronic device includes the cover plate as described in claim 10.

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