Composite powder, composite ceramic and preparation method and application thereof

Abstract

The invention provides composite powder, composite ceramic and a preparation method and application thereof, and can be applied to the technical field of ceramic materials. The composite powder comprises a second material doped with a first material, the first material is a composite material formed by solid solution of yttrium oxide into crystal lattices of bismuth oxide, and the second material is a composite material formed by solid solution of yttrium oxide into crystal lattices of zirconium oxide.

Description

Technical Field

[0001] The present application relates to the technical field of ceramic materials, and in particular to a composite powder, a composite ceramic, and a preparation method and application thereof. Background Art

[0002] Server substrate materials typically require excellent electrical, mechanical, heat dissipation, and reliability. A server substrate is a key component within the server, primarily used to support and connect various electronic components to ensure efficient server operation. Currently, glass fiber-reinforced epoxy resin is the most commonly used material for server substrates. However, prolonged exposure to high temperatures can lead to performance degradation and even material deformation, as well as low thermal stability and limited heat resistance.

[0003] Zirconia's high melting point (2715°C) and high chemical stability enable it to remain stable in extreme environments, making it suitable for key server components such as heat sinks and substrates, ensuring stable operation in high-temperature and corrosive environments. Yttria-stabilized zirconia ceramics, in particular, are made by adding yttria to alter the phase transition temperature range of zirconium dioxide, producing cubic crystals that are stable at room temperature. These ceramics possess exceptional hardness and strength, can withstand significant pressure and impact, and have high flexural strength, making them suitable for server substrate materials.

[0004] However, in the related art, the sintering temperature of yttria-stabilized zirconia ceramics is relatively high (generally above 1500° C.) and the thermal stability is relatively poor. Summary of the Invention

[0005] In view of the above problems, the present application provides a composite powder, a composite ceramic, and a preparation method and application thereof.

[0006] According to the first aspect of the present application, a composite powder is provided, which includes a second material doped with a first material, wherein the first material is a composite material formed by dissolving yttrium oxide in a lattice of bismuth oxide, and the second material is a composite material formed by dissolving yttrium oxide in a lattice of zirconium oxide.

[0007] The second aspect of the present application provides a method for preparing a composite powder, which comprises: mixing a second material with a first mixed liquid to obtain an oil phase suspension, wherein the first mixed liquid is a mixture of cyclohexane, a surfactant and n-hexanol; adding a second mixed liquid to the suspension and continuously stirring to form an oil-in-water microemulsion, wherein the second mixed liquid is a nitric acid solution of bismuth nitrate and yttrium nitrate; adjusting the pH of the microemulsion to 9.5-10.5, stirring, filtering and washing to obtain a precursor; and calcining the precursor to obtain the composite powder.

[0008] A third aspect of the present application provides a composite ceramic, which is formed by sintering a raw material including a composite powder at 1100° C. to 1300° C., wherein the composite powder is the composite powder described above.

[0009] The fourth aspect of the present application provides a method for preparing a composite ceramic, which is characterized in that it includes the following steps: mixing the composite powder, binder and water evenly and then granulating, grinding and sieving to obtain composite particles, wherein the above-mentioned composite powder is the above-mentioned composite powder; pressing the above-mentioned composite particles at 20~30MPa to obtain a molded blank; sintering the above-mentioned molded blank at 1100℃~1300℃ to obtain a composite ceramic.

[0010] A fifth aspect of the present application provides a server, which includes the composite ceramic or the composite ceramic produced by the above method. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The above contents and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0012] Figure 1 The following schematically shows a flow chart of a method for preparing a composite powder according to an embodiment of the present application;

[0013] Figure 2 A flow chart schematically illustrates a method for preparing a composite ceramic according to an embodiment of the present application;

[0014] Figure 3 An electron microscope image of the 15YSB-YSZ composite powder provided in Example 2 of the present application is shown;

[0015] Figure 4 The energy dispersive X-ray spectrum of the 15YSB-YSZ composite powder provided in Example 2 of the present application is shown;

[0016] Figure 5 The X-ray diffraction pattern of the 5YSB-YSZ composite powder provided in Example 1 of the present application, the standard pattern of the tetragonal phase of YSB, and the standard pattern of the face-centered cubic phase of YSZ are shown;

[0017] Figure 6 An electron microscope image of the composite ceramic provided in the embodiment of the present application is shown;

[0018] Figure 7 The X-ray photoelectron spectrum of the composite ceramic provided in the examples of the present application is shown. DETAILED DESCRIPTION

[0019] Below, the embodiment of the present application will be described. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present application. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiment of the present application. However, it is obvious that one or more embodiments can also be implemented without these specific details. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present application.

[0020] The terms used herein are only for describing specific embodiments and are not intended to limit this application. The terms "comprise," "include," etc. used herein indicate the presence of the features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0021] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0022] When expressions such as "at least one of A, B, and C, etc." are used, they should generally be interpreted in accordance with the meaning commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0023] In the present application, the composite material formed by solid dissolving yttrium oxide into the lattice of zirconium oxide may be referred to as yttria-stabilized zirconia; the composite material formed by solid dissolving yttrium oxide into the lattice of bismuth oxide may be referred to as yttria-stabilized bismuth oxide.

[0024] In the process of implementing this application, it was found that yttria-stabilized bismuth oxide can be doped into yttria-stabilized zirconia to form a composite powder. Using this composite powder to prepare composite ceramics can reduce the sintering temperature of the composite ceramics and improve their thermal stability.

[0025] In view of this, embodiments of the present application provide a composite powder comprising a second material doped with a first material. The first material is a composite material formed by solid-dissolving yttrium oxide in the lattice of bismuth oxide, and the second material is a composite material formed by solid-dissolving yttrium oxide in the lattice of zirconium oxide. Specifically, the first material may be yttria-stabilized bismuth oxide, and the second material may be yttria-stabilized zirconia.

[0026] According to the embodiments of the present application, a first material (yttria-stabilized bismuth oxide) is doped into a second material (yttria-stabilized zirconia) to form a composite powder. Using the composite powder to prepare composite ceramics can reduce the sintering temperature of the composite powder and reduce the preparation cost of the composite ceramics; increase the vacancy oxygen content of the sintered composite ceramics and improve their thermal stability; and improve the mechanical properties of the composite ceramics.

[0027] The present application has no particular limitation on the detection method of the first material or the second material, as long as the purpose of the present application can be achieved. For example, the composite powder can be detected by X-ray diffraction analysis to determine the components in the composite powder.

[0028] It should be noted that, in this application, the above-mentioned doping may refer to adding a first material to a second material to change certain properties or characteristics of the second material. In the composite powder provided in this application, the first material and the second material may exist independently.

[0029] According to an embodiment of the present application, in the composite powder, the molar ratio of the first material to the second material may be 1:99 to 1:4. For example, the molar ratio of the first material to the second material may be 1:99, 1:90, 1:80, 1:70, 1:60, 1:50, 1:40, 3:97, 1:30, 1:20, 1:10, 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, or a range between any two of the above values.

[0030] The present application does not impose any particular restrictions on the method for detecting the molar ratio of the first material and the second material, as long as the purpose of the present application can be achieved. For example, the composite powder can be detected by X-ray diffraction analysis to determine the components in the composite powder, and the molar ratio of the first material and the second material can be determined by the peak area of each component.

[0031] According to an embodiment of the present application, in the composite powder, the molar ratio of yttrium, bismuth and zirconium can be (2-180): (5-100): (1440-1820). For example, the molar ratio of yttrium, bismuth and zirconium can be 2:5:1440, 2:5:1600, 2:5:1820, 2:25:1600, 2:50:1600, 2:75:1600, 2:100:1600, 2:100:1820, 50:5:1440, 50:5:1600, 50:5:1820, 50:25:1440, 50:25:160 ... 5:1820, 50:50:1440, 50:50:1600, 50:50:1820, 50:75:1440, 50:75:1600, 50:75:1820, 50:100:1440, 50:100:1600, 50:100:1820, 100:25:1600, 150:25:1600, 180:25:1600 or the range between any two of these ratios.

[0032] The present application does not impose any particular restrictions on the method for detecting the molar ratio of yttrium, bismuth and zirconium in the composite powder, as long as the purpose of the present application can be achieved. For example, the composite powder can be detected by energy dispersive X-ray spectroscopy to determine the content of each element in the composite powder.

[0033] In some embodiments of the present application, the molar ratio of yttrium to bismuth in the first material may be (1-2):(2-3). For example, the molar ratio of yttrium to bismuth in the first material may be 1:2, 1:2.5, 1:3, 1:1, 2:2.5, 2:3, or a range between any two of the above ratios.

[0034] In some embodiments of the present application, the molar content of yttrium oxide in the second material can be 5% to 10%. For example, the molar content of yttrium oxide in the second material can be 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, or a range between any two of the above values. Optionally, the molar content of yttrium oxide in the second material can be 8%. In this case, yttrium oxide can change the phase transition temperature range of zirconium dioxide, producing cubic crystals that are stable at room temperature, so that the second material has extremely high hardness and strength, can withstand greater pressure and impact, and has high bending strength.

[0035] By controlling the molar ratio of the first material and the second material, the molar ratio of each element in the composite powder, the molar content of yttrium oxide in the first material, and the molar content of yttrium oxide in the second material within the above ranges, a composite powder is formed, which is beneficial to further reduce the sintering temperature of the composite powder and improve the thermal stability of the sintered composite ceramic.

[0036] The present application has no particular restrictions on the size of the composite powder, as long as the purpose of the present application can be achieved. For example, the size of the composite powder can be micrometer-level, nanometer-level, etc. In some embodiments of the present application, the size of the composite powder can be nanometer-level. In this case, the composite ceramics sintered from the composite powder have better mechanical properties, lower sintering temperature, and better thermal stability. The present application has no particular restrictions on the morphology of the composite powder, as long as the purpose of the present application can be achieved. For example, the morphology of the composite powder can be spheres, ellipsoids, rods, etc. In some embodiments of the present application, the morphology of the composite powder can be spheres or ellipsoids. The morphology of spheres and ellipsoids can make it easier for the mixed powder to achieve composite ceramics with uniform structure, high density and mechanical properties during the sintering process.

[0037] The second aspect of the present application provides a method for preparing a composite powder. Figure 1 The flowchart of the method for preparing composite powder according to an embodiment of the present application is schematically shown.

[0038] like Figure 1 As shown, the preparation method includes steps S110 to S140.

[0039] In step S110 , the second material is mixed with the first mixed liquid to obtain an oil phase suspension, wherein the first mixed liquid is a mixed liquid of cyclohexane, a surfactant, and n-hexanol.

[0040] In step S120, a second mixed liquid is added to the suspension and stirred continuously to form a water-in-oil microemulsion, wherein the second mixed liquid is a nitric acid solution of nitric acid and yttrium nitrate.

[0041] In step S130, the pH of the microemulsion is adjusted to 9.5-10.5, and the precursor is obtained after stirring, filtering, and washing. For example, the pH of the microemulsion can be adjusted to 9.5, 9.6, 9.7, 9.8, 9.9, 10.0, 10.1, 10.2, 10.3, 10.4, 10.5, or a range between any two of the above values.

[0042] In step S140 , the precursor is calcined to obtain a composite powder.

[0043] According to the embodiments of the present application, a water-in-oil microemulsion can be used to prepare a composite powder. The aqueous phase can be a solution of bismuth ions and yttrium ions dissolved in a nitric acid solution, i.e., the second mixed solution; the oil phase can be a first mixed solution formed by cyclohexane, a surfactant, and n-hexanol, wherein n-hexanol can be used as a co-surfactant; the second material is mixed with the first mixed solution to obtain an oil phase suspension. The second mixed solution is added to the suspension, and continuous stirring can break the stratification between the water and oil interfaces, and the action of the surfactant can form an oil-in-water microemulsion. In this state, ammonia water is added to the microemulsion as a precipitant, which penetrates into the microemulsion bubbles, and a chemical reaction occurs in the microemulsion bubbles to generate hydroxides. The hydroxide nucleates and grows in the microemulsion bubbles, and the newly generated powder particles come into contact with the surfactant after growing to a certain extent. Due to the action of the surfactant, the growth of the grains is restricted, thereby controlling the size of the precursor and, in turn, the size of the composite powder. Yttria-stabilized bismuth oxide readily grows into rod-shaped powders during the nucleation and growth process. The microemulsion method allows for controlled morphology and size of the composite powder, resulting in a nano-sized, relatively regular composite powder. After calcining the precursor, a uniformly mixed composite powder of the first and second materials is obtained.

[0044] According to an embodiment of the present application, in step S110, the temperature of the first mixed liquid may be 35°C to 45°C. For example, the temperature of the first mixed liquid may be 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, or a range between any two of the above values. The temperature of the suspension may be 35°C to 45°C. For example, the temperature of the suspension may be 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, or a range between any two of the above values. When the temperatures of the first mixed liquid and the suspension are within the above ranges, an oil-in-water microemulsion may be formed in step S120; temperatures that are too high or too low are not conducive to the formation of the oil-in-water microemulsion in step S120. For example, when the temperatures of the first mixed liquid and the suspension are 60°C, an oil-in-water microemulsion cannot be formed in step S120.

[0045] According to an embodiment of the present application, in step S110, the surfactant includes at least one of Triton X-100, polyethylene glycol, and polyvinyl pyrrolidone. Exemplarily, the surfactant can be Triton X-100, polyethylene glycol, or polyvinyl pyrrolidone. The surfactant can also be a mixture of at least two of Triton X-100, polyethylene glycol, and polyvinyl pyrrolidone. The surfactant can also be a mixture of Triton X-100, polyethylene glycol, and polyvinyl pyrrolidone. In some embodiments of the present application, the surfactant can include Triton X-100. The oil phase formed by cyclohexane, Triton X-100, and n-hexanol has advantages such as good emulsification performance, small and uniform distribution of emulsion particle size, and high chemical stability.

[0046] According to an embodiment of the present application, in step S110, the molar ratio of cyclohexane, surfactant, and n-hexanol in the first mixed liquid can be (6-8):(2-4):(1-3). For example, the molar ratio of cyclohexane, surfactant, and n-hexanol in the first mixed liquid can be 6:2:1, 7:3:2, 8:4:3, or a range between any two of the above ratios. A molar ratio of cyclohexane, surfactant, and n-hexanol within the above range is more conducive to forming a stable microemulsion structure and precisely controlling the droplet size of the microemulsion. In some embodiments of the present application, the molar ratio of cyclohexane, surfactant, and n-hexanol in the first mixed liquid can be 7:3:2.

[0047] For example, in step S110, the surfactant and n-hexanol can be added to cyclohexane in the above ratio, ultrasonically mixed, and then continuously stirred in a water bath to form a uniform first mixed solution. The second material is then added to the first mixed solution, and continuously stirred to obtain an oil phase suspension.

[0048] According to an embodiment of the present application, in step S120, the temperature of the second mixed liquid may be 35°C to 45°C. For example, the temperature of the second mixed liquid may be 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, or a range between any two of the above values. The temperature of the microemulsion is 35°C to 45°C. For example, the temperature of the microemulsion may be 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, or a range between any two of the above values. When the temperatures of the second mixed liquid and the microemulsion are within the above ranges, an oil-in-water microemulsion can be formed in step S120; temperatures that are too high or too low are not conducive to the formation of the oil-in-water microemulsion in step S120. For example, when the temperature of the second mixed liquid and the microemulsion is 60°C, an oil-in-water microemulsion cannot be formed in step S120.

[0049] According to an embodiment of the present application, in step S120, in the second mixed solution, the concentration of bismuth nitrate and yttrium nitrate is 2-3 mol / L. Exemplarily, in the second mixed solution, the concentration of bismuth nitrate and yttrium nitrate is 2.0 mol / L, 2.1 mol / L, 2.2 mol / L, 2.3 mol / L, 2.4 mol / L, 2.5 mol / L, 2.6 mol / L, 2.7 mol / L, 2.8 mol / L, 2.9 mol / L, 3.0 mol / L or the range between any two of the above values. In the second mixed solution, the concentration of nitric acid can be 61 wt%-75 wt%. Exemplarily, the concentration of nitric acid can be 61 wt%, 62 wt%, 63 wt%, 64 wt%, 65 wt%, 66 wt%, 67 wt%, 68 wt%, 69 wt%, 70 wt%, 71 wt%, 72 wt%, 73 wt%, 74 wt%, 75 wt% or the range between any two of the above values.

[0050] The present application does not particularly limit the rate at which the second mixed solution is added to the suspension in step S120, as long as the purpose of the present application can be achieved. In order to better form a water-in-oil microemulsion, the rate at which the second mixed solution is added to the suspension can also be regulated. For example, the second mixed solution can be added dropwise to the suspension, or the time for adding the second mixed solution to the suspension can be set to no less than a preset value, such as 5 minutes, 10 minutes, 30 minutes, etc., to regulate the rate at which the second mixed solution is added to the suspension.

[0051] For example, in step S120, bismuth nitrate pentahydrate and yttrium nitrate hexahydrate can be weighed according to the above molar ratio and dissolved in nitric acid, and then continuously stirred in a 40°C water bath to form a uniform second mixed solution. The second mixed solution is then added dropwise to the suspension while continuously stirring to form a water-in-oil microemulsion.

[0052] The present application has no particular limitation on the pH adjustment method of the microemulsion in step S130, as long as the purpose of the present application can be achieved. For example, the pH of the microemulsion can be adjusted by adding ammonia water.

[0053] The present application does not particularly limit the stirring time in step S130, as long as the purpose of the present application can be achieved. For example, the stirring time can be 1 to 2 hours. The present application does not particularly limit the filtering method in step S130, as long as the purpose of the present application can be achieved. For example, the filtering method can be atmospheric filtration, suction filtration, etc. The present application does not particularly limit the washing method and number of times in step S130, as long as the purpose of the present application can be achieved. For example, the washing method can be water washing, ethanol washing, etc.; the number of washing times can be 1 to 5 times.

[0054] For example, in step S130, aqueous ammonia can be added dropwise to the microemulsion to adjust the pH value of the microemulsion. The solution after the aqueous ammonia is added is stirred in a constant temperature water bath for 1 to 2 hours, taken out, and filtered and washed to obtain a precursor.

[0055] This application has no special restrictions on the temperature control method of the first mixed liquid and suspension in step S110, the temperature control method of the second mixed liquid and microemulsion in step S120, and the temperature control method of the pH adjustment process of the microemulsion in step S130. As long as the purpose of this application can be achieved, temperature control can be performed by using constant temperature equipment, such as a constant temperature reactor, a constant temperature water bath, an oil bath, a sand bath, etc.

[0056] According to an embodiment of the present application, in step S140, the calcination temperature may be 500°C to 700°C. For example, the calcination temperature may be 500°C, 520°C, 550°C, 580°C, 600°C, 620°C, 650°C, 680°C, 700°C, or a range between any two of the above values. The calcination time may be 1 to 2 hours. For example, the calcination time may be 1.0h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2.0h, or a range between any two of the above values. The calcination temperature and time within the above ranges can optimize the crystal structure of the composite powder and improve the stability of the composite powder.

[0057] In a third aspect, the present application provides a composite ceramic, wherein the composite ceramic is formed by sintering raw materials including a composite powder at a temperature between 1100°C and 1300°C, wherein the composite powder is the composite powder described above. Exemplarily, the sintering temperature can be 1100°C, 1120°C, 1150°C, 1170°C, 1200°C, 1230°C, 1250°C, 1270°C, 1300°C, or a range between any two of the above values.

[0058] According to an embodiment of the present disclosure, by sintering raw materials including composite powder at 1100°C~1300°C, a composite ceramic formed by a first material and a second material can be obtained. The performance of the second material is improved by doping the first material. The composite ceramic has a low sintering temperature and good thermal stability and mechanical properties.

[0059] In some embodiments of the present application, the composite ceramic may include lattice oxygen and vacancy oxygen. The vacancy oxygen content may be no less than 55% based on the total amount of lattice oxygen and vacancy oxygen. For example, the vacancy oxygen content may be 55%, 60%, 62%, 63%, 65%, 67%, 70%, or a range between any two of the above values based on the total amount of lattice oxygen and vacancy oxygen. A higher vacancy oxygen content can further improve the thermal stability of the composite ceramic.

[0060] According to an embodiment of the present disclosure, in the composite ceramic, the first material is at least partially dissolved in the lattice of the second material. It is understood that the first material can be partially dissolved in the lattice of the second material, or the first material can be completely dissolved in the lattice of the second material.

[0061] In some embodiments of the present application, the density of the composite ceramic may be no less than 93%, and further, the density of the composite ceramic may be no less than 95%. For example, the density of the composite ceramic may be 93.0%, 93.2%, 93.5%, 93.8%, 94.0%, 94.2%, 94.5%, 94.8%, 95.0%, 95.2%, 95.5%, 95.8%, 96.0%, 96.2%, 96.5%, 96.8%, 97.0%, 97.2%, 97.6%, 97.8%, 98.0%, 98.3% or a range between any two of the above values. The density of the composite ceramic within the above range can further improve the mechanical properties and thermal stability of the composite ceramic.

[0062] This application also provides a method for preparing a composite ceramic. Figure 2 The flowchart of the method for preparing the composite ceramic according to an embodiment of the present application is schematically shown.

[0063] like Figure 2 As shown, the preparation method includes steps S210 to S230.

[0064] In step S210 , the composite powder, the binder and water are evenly mixed and granulated, and then ground and sieved to obtain composite particles. The composite powder is the composite powder mentioned above.

[0065] In step S220, the composite particles are pressed at a pressure of 20 to 30 MPa to obtain a preform. For example, the composite particles can be pressed at a pressure of 20 MPa, 21 MPa, 22 MPa, 23 MPa, 24 MPa, 25 MPa, 26 MPa, 27 MPa, 28 MPa, 29 MPa, 30 MPa, or a range between any two of the above values to obtain a preform.

[0066] In step S230, the molded blank is sintered at 1100° C. to 1300° C. to obtain a composite ceramic. For example, the molded blank can be sintered at the following temperatures: 1100° C., 1120° C., 1150° C., 1170° C., 1200° C., 1230° C., 1250° C., 1270° C., 1300° C., or a range between any two of the above values.

[0067] The present application has no particular limitation on the amount of binder added in step S210, as long as the purpose of the present application can be achieved. For example, the amount of binder added can be 3% to 15% of the mass of the composite powder.

[0068] The present application does not particularly limit the method for pressing the preform in step S220, as long as the objectives of the present application are achieved. For example, the composite particles can be added to a stainless steel mold and pressurized to 20-30 MPa using a hydraulic press. The present application does not particularly limit the holding time of the preform in step S220, as long as the objectives of the present application are achieved. For example, the holding time can be 1-5 minutes.

[0069] The present application has no particular limitation on the sintering time of the molded blank in step S230 as long as the purpose of the present application can be achieved. For example, the sintering time of the molded blank can be 1.5 to 3 hours.

[0070] The present application also provides a server, which includes the above-mentioned composite ceramic or the composite ceramic produced by the above-mentioned method.

[0071] In some embodiments of the present application, relevant technicians can apply the composite ceramics to different parts of the server according to actual needs. For example, the composite ceramics can be applied to heat sinks, substrates, etc.

[0072] The present application is described in detail below with reference to the examples to facilitate understanding of the present invention by those skilled in the art. It is necessary to point out that the examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present application. Relevant technicians can make non-essential improvements and adjustments to the present application based on the above disclosure, which should still fall within the scope of protection of the present application. At the same time, the raw materials mentioned below that are not described in detail are all commercially available products; the process steps or preparation methods that are not mentioned in detail are all process steps or preparation methods known to relevant technicians.

[0073] Test Method

[0074] X-ray diffraction test

[0075] The prepared composite powder and composite ceramic were subjected to X-ray diffraction analysis using an X-ray diffractometer. X-ray diffraction data was collected at a rate of 10° / min. The composition of the prepared material was obtained by analyzing the obtained X-ray diffraction patterns.

[0076] Density test

[0077] The density of composite ceramics is measured using the Archimedes drainage method. The specific test method is as follows:

[0078] (1) Place the composite ceramic in a beaker filled with deionized water and then boil it in a resistance-controlled electric heater for 2 h to allow the water to fill the open pores in the sample.

[0079] (2) After boiling for 2 hours, take out the composite ceramic, then put the composite ceramic into deionized water and measure the mass m of the composite ceramic in water. 水 .

[0080] (3) Wipe away the moisture on the surface of the composite ceramic, and then measure the mass m of the composite ceramic in the air. 湿 .

[0081] (4) Place the composite ceramic in a 60°C drying oven and dry for 12 hours, then measure the mass m of the composite ceramic in air. 干 .

[0082] The calculation formula of volume density is as shown in formula (1).

[0083] (1);

[0084] Among them, ρ 水 -Density of water, take 1g / cm 3 .

[0085] The theoretical density of the composite ceramic is calculated using formula (2) according to the mixing rule.

[0086] (2);

[0087] in, and They represent the mass fractions of yttria-stabilized bismuth oxide and yttria-stabilized zirconia, respectively, in %.

[0088] and They represent the theoretical density of yttria-stabilized bismuth oxide (8.9 g / cm 3 ) and the theoretical density of yttria-stabilized zirconia (6.1 g / cm 3 ).

[0089] The relative density of the composite ceramics was calculated using formula (3).

[0090] (3).

[0091] Mechanical testing

[0092] The bending strength of composite ceramics is measured using an electronic universal testing machine. The specific test method is as follows:

[0093] The composite ceramic was processed into rectangular specimens measuring 3 × 4 × 25 mm using an internal cutting machine. Each group of specimens consisted of at least five specimens. All specimens were cleaned and then dried in a drying oven. The specimens were fixed in a three-point bending fixture, and the flexural strength was measured using a computer-controlled electronic universal testing machine. The indenter was aligned with the center of the specimen, maintaining a span L of 20 mm. Pressure was applied at a constant rate of 0.2 mm / min until the specimen broke. The maximum test load on the load-displacement curve was recorded on the computer, and the flexural strength was calculated using Equation (4).

[0094] (4);

[0095] in: is the bending strength, in MPa; F is the maximum load of the specimen strip, in kN; L is the fixture span, in mm; b is the width of the specimen strip, in mm; h is the thickness of the specimen strip, in mm.

[0096] X-ray photoelectron spectroscopy test (oxygen vacancy concentration test)

[0097] A block no larger than 2 mm x 2 mm was removed from the composite ceramic and subjected to X-ray photoelectron spectroscopy. Selecting an element during testing yielded a full energy level spectrum and individual elemental spectra. Using Casa software, all obtained spectra were calibrated by calibrating the main peak position of the C spectrum. The O spectrum was then fitted with peaks, and the peak area percentage was used to calculate the oxygen vacancy concentration in the sample.

[0098] Shape detection

[0099] Scanning electron microscopy was used to examine the morphology of the composite powders and composite ceramics.

[0100] Example 1

[0101] This embodiment provides a composite powder and a composite ceramic, wherein the composite powder comprises yttria-stabilized bismuth oxide (denoted as YSB) doped with yttria-stabilized zirconia (denoted as YSZ).

[0102] The composite powder and composite ceramic are prepared by the following method:

[0103] (1) 13.8 ml of n-hexanol and 10 ml of Triton X-100 were added to 60 ml of cyclohexane. After ultrasonication for 30 min, the mixture was stirred continuously for 30 min in a 40°C water bath to form a uniform solution, i.e., the first mixed solution. 10 g of YSZ powder (with a molar content of yttrium oxide of 8%, face-centered cubic phase) was added to the first mixed solution and stirred continuously for 30 min to obtain an oil phase suspension.

[0104] (2) Weigh 3.9 g of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) and 2.7 g of yttrium nitrate hexahydrate (Y(NO3)3·6H2O) and dissolve them in nitric acid to obtain and The mixed solution and The concentration of the mixture was 2 mol / L and the mixture was stirred continuously in a water bath at 40°C to form a uniform solution, i.e., the second mixed solution.

[0105] (3) Add the second mixed solution dropwise into the suspension and continue stirring to form an oil-in-water microemulsion.

[0106] (4) The obtained microemulsion was stirred in a constant temperature water bath for 30 minutes, and then ammonia was added dropwise to adjust the pH value of the solution. The pH value was controlled at 9.5-10.5. The solution after adding ammonia was stirred in a constant temperature water bath for 2 hours and then removed. The solution was then filtered and washed with deionized water and anhydrous ethanol three times respectively to obtain the precursor.

[0107] (5) The precursor was calcined at 600 °C for 2 h to obtain a YSB-YSZ composite powder, i.e., 5 mol% YSB-YSZ, denoted as 5YSB-YSZ composite powder.

[0108] (6) The composite powder was added with a small amount of polyvinyl alcohol binder and deionized water for granulation, and then ground and sieved to obtain composite particles. The composite particles were weighed and added to a 30 mm stainless steel mold. The mold was pressurized to 25 MPa at a pressurization speed of 1 MPa / s using a hydraulic press, and the pressure was maintained for 2 min. After drying, the YSB-YSZ green body was obtained.

[0109] (7) The YSB-YSZ green body was sintered at 1100 °C for 2 h to obtain YSB-YSZ composite ceramics, i.e., 5 mol% YSB-YSZ, denoted as 5YSB-YSZ.

[0110] Example 2

[0111] This embodiment provides a composite powder and a composite ceramic and a preparation method thereof, with reference to Example 1, except that, in step (1) of this embodiment, the amount of YSZ powder added is 2.52 g, i.e., 15 mol% YSB-YSZ, denoted as 15YSB-YSZ.

[0112] Example 3

[0113] This embodiment provides a composite powder and a composite ceramic and a preparation method thereof, with reference to Example 1, except that, in step (1) of this embodiment, the amount of YSZ powder added is 4.72 g, i.e., 10 mol% YSB-YSZ, denoted as 10YSB-YSZ.

[0114] Example 4

[0115] This embodiment provides a composite powder and a composite ceramic and a preparation method thereof, with reference to Example 1, except that, in step (1) of this embodiment, the amount of YSZ powder added is 17 g, i.e., 3 mol% YSB-YSZ, denoted as 3YSB-YSZ.

[0116] Example 5

[0117] This embodiment provides a composite powder and a composite ceramic and a preparation method thereof, with reference to Example 1, except that in step (7) of this embodiment, the sintering temperature is 1200°C.

[0118] Example 6

[0119] This embodiment provides a composite powder and a composite ceramic and a preparation method thereof, with reference to Example 1, except that in step (7) of this embodiment, the sintering temperature is 1300°C.

[0120] Example 7

[0121] This embodiment provides a composite powder and a composite ceramic and a preparation method thereof, with reference to Example 2, except that in step (7) of this embodiment, the sintering temperature is 1200°C.

[0122] Example 8

[0123] This embodiment provides a composite powder and a composite ceramic and a preparation method thereof, with reference to Example 2, except that in step (7) of this embodiment, the sintering temperature is 1300°C.

[0124] Example 9

[0125] This embodiment provides a composite powder and a composite ceramic and a preparation method thereof, with reference to Example 3, except that in step (7) of this embodiment, the sintering temperature is 1200°C.

[0126] Example 10

[0127] This embodiment provides a composite powder and a composite ceramic and a preparation method thereof, with reference to Example 3, except that in step (7) of this embodiment, the sintering temperature is 1300°C.

[0128] Example 11

[0129] This embodiment provides a composite powder and a composite ceramic and a preparation method thereof, with reference to Example 4, except that in step (7) of this embodiment, the sintering temperature is 1200°C.

[0130] Example 12

[0131] This embodiment provides a composite powder and a composite ceramic and a preparation method thereof, with reference to Example 4, except that in step (7) of this embodiment, the sintering temperature is 1300°C.

[0132] Comparative Example 1

[0133] This embodiment provides a yttria-stabilized zirconia ceramic and a preparation method thereof, which are prepared by the following method:

[0134] (1) Yttria-stabilized zirconia powder was added with a small amount of polyvinyl alcohol binder and deionized water for granulation, and then ground and sieved to obtain composite particles. The composite particles were weighed and added to a 30 mm stainless steel mold. The mold was pressurized to 25 MPa at a pressurization speed of 1 MPa / s using a hydraulic press, and the pressure was maintained for 2 min. After drying, the YSZ green body was obtained.

[0135] (2) The YSZ green body was sintered at 1600℃ for 8h to obtain YSZ ceramics.

[0136] The morphology of the 5YSB-YSZ composite powder provided in Example 1 was detected using a scanning electron microscope. Figure 3 The electron microscope image and energy dispersive X-ray spectrum of 5YSB-YSZ composite powder provided in Example 1 of the present application are shown. Among them, (a) and (b) are electron microscope images of YSB-YSZ composite powder at different magnifications. Figure 3 As can be seen from (a) and (b), the YSB-YSZ composite powder prepared by the microemulsion method shows the accumulation of nano-scale particles under a high-power magnifying glass, without the appearance of rod-shaped YSB and no agglomeration.

[0137] The 15YSB-YSZ composite powder provided in Example 2 was subjected to energy dispersive X-ray spectroscopy testing to detect the distribution and atomic percentage of zirconium (Zr), yttrium (Y), and bismuth (Bi) elements in the 15YSB-YSZ composite powder. Figure 4 The energy dispersive X-ray spectrum of the 15YSB-YSZ composite powder provided in Example 1 of the present application is shown. Among them, (a) is the Zr element distribution diagram, (b) is the Y element distribution diagram, (c) is the Bi element distribution diagram, and (d) is the atomic percentage of Zr, Y, and Bi elements. Figure 4 From (a), (b) and (c), we can see that the distribution of Zr, Y and Bi elements is relatively uniform. Figure 4 As shown in (d), the Bi / Zr ratio in the YSB-YSZ composite powder is 0.34. These ratios are close to the 15 mol% YSB in the raw material. This indicates that the composite powder prepared by the microemulsion method has good mixing uniformity.

[0138] The 5YSB-YSZ composite powder provided in Example 1 was subjected to X-ray diffraction test, and the test results were as follows: Figure 5 As shown, Figure 5 The X-ray diffraction pattern of the 5YSB-YSZ composite powder provided in Example 1 of the present application, the standard pattern of the tetragonal phase of YSB, and the standard pattern of the face-centered cubic phase of YSZ are shown. Figure 5 Comparing the standard spectra of YSB and YSZ demonstrates that the crystal structure of YSZ remains unchanged in Example 1, remaining in the face-centered cubic phase. The addition of the Y element stabilizes YSB in the tetragonal phase, successfully preparing a 5YSB-YSZ composite powder.

[0139] The morphology of the 5YSB-YSZ composite ceramic provided in Example 1, the 15YSB-YSZ composite ceramic provided in Example 2, and the 10YSB-YSZ composite ceramic provided in Example 3 was detected using a scanning electron microscope. Figure 6 The electron microscope images of the composite ceramics provided in the examples of the present application are shown. Among them, (a) is the electron microscope image of the 5YSB-YSZ composite ceramic provided in Example 1, (b) is the electron microscope image of the 10YSB-YSZ composite ceramic provided in Example 3, and (c) is the electron microscope image of the 15YSB-YSZ composite ceramic provided in Example 2. Figure 6 It can be seen that under a high-power magnifying glass, the composite ceramic provided in the embodiment of the present application has obvious grain boundaries, a good sintering state, and a good density.

[0140] X-ray photoelectron spectroscopy was performed on the YSB-YSZ composite ceramics provided in Example 1 (5YSB-YSZ), Example 3 (10YSB-YSZ), and Example 4 (3YSB-YSZ) to determine the oxidation state of each component element in the YSB-YSZ composite ceramics. Figure 7 The X-ray photoelectron spectra of the composite ceramics provided in Examples 1, 3 and 4 of the present application are shown, wherein (a) is a full spectrum of the composite ceramic, (b) is a high-resolution detailed spectrum of the Bi 4f element of the composite ceramic, (c) is a high-resolution detailed spectrum of the O 1s element of 3YSB-YSZ, (d) is a high-resolution detailed spectrum of the O 1s element of 5YSB-YSZ, and (e) is a high-resolution detailed spectrum of the O 1s element of 10YSB-YSZ.

[0141] Figure 7 (a) shows the XPS spectrum of YSB-YSZ. The entire spectrum, acquired from 0 to 1150 eV, includes both core and satellite binding energy peaks for Zr, Y, Bi, C, and O. All peaks were calibrated to the C 1s reference peak at 285 eV, allowing the binding energy peaks to be determined based on the reference peaks. Figure 7Figure (a) shows the binding energy peaks for Zr3d at ~183 eV, Y3d at ~158 eV, O1s at ~532 eV, and Bi4f at ~158 eV. In the full XPS spectrum, the binding energy peaks for the Zr4p, Zr3p, Y3s, and Bi4d states appear at ~29 eV, ~331 eV, ~395 eV, and ~440 eV, respectively. A satellite peak for O (KLL) is also observed at ~986 eV. Figure 7 In (b), the high-resolution detailed spectrum of Bi 4f elements is provided. The three YSB-doped compositions show two spectral peaks, namely Bi 4f 7 / 2 and Bi 4f 5 / 2 With the increase of YSB doping concentration, the binding energy intensity corresponding to Bi 4f also increases. The substituent Bi includes 4f 7 / 2 and 4f 5 / 2 states, corresponding to ~158 eV and ~163 eV, respectively. In addition, in Bi4f 7 / 2 A low-intensity peak appears on the left side of the peak, which indicates that the Bi in these samples is not only in the Bi 3+ It is speculated that the reason may be that some of the Bi elements doped into ZrO2 have undergone transition.

[0142] When Bi is doped into ZrO2 3+ and Y 3+ When low-valent cations are present, they will occupy Zr 4+ In order to maintain electrical neutrality, oxygen doping will produce oxygen ion vacancies ( ), as shown in formula (1) and formula (2). At high temperatures, atomic vibrations can enable oxygen ions to migrate between oxygen vacancies.

[0143] .....................(1)

[0144] .....................(2)

[0145] therefore, The concentration of the compound is an important factor affecting its performance.

[0146] In solid-state chemistry, computational When the relative concentration of O is greater than 1%, the XPS spectrum of O 1s core level is a recognized method. The O1s core peak can be split to obtain two peaks, indicating that O in the composite material exists in two states, namely lattice oxygen (O L ) and vacancy oxygen (O VThe oxygen vacancies obtained by doping in YSZ will reduce the total number of oxygen atoms, thereby increasing the binding energy position of the corresponding oxygen element. Therefore, the absorption peak of oxygen with higher binding energy corresponds to the position of vacant oxygen. Using casa-XPS software to perform peak fitting of the O element, two peaks with binding energies of ~529 eV and ~531 eV can be obtained, which correspond to the absorption peaks of O and O, respectively. L and O V Table 1 shows the L and O V The peak area fitting results.

[0147] Table 1

[0148]

[0149] As shown in Table 1, the O V The percentages are 55.76%, 64.9% and 63.72% respectively. V The concentration increases with increasing YSB doping levels, then decreases slightly. This is attributed to the fact that increasing the doping level introduces more low-valent oxygen ions into the YSZ lattice, creating more oxygen vacancies. However, when the doping level is excessive, some of these oxygen vacancies form defect associations with existing defects in the YSZ lattice, reducing the effective oxygen vacancy concentration. The oxygen vacancy concentration results in Table 1 indicate that the 5YSB-YSZ composite ceramic has the highest oxygen vacancy concentration.

[0150] The density and flexural strength of the composite ceramics provided in Examples 1 to 12 were tested, and the flexural strength of the yttria-stabilized zirconia ceramic provided in Comparative Example 1 was tested. The test results are shown in Table 2.

[0151] Table 2

[0152]

[0153] Generally speaking, a density exceeding 95% is considered a dense ceramic. As shown in Table 2, YSB-YSZ composite ceramics with excellent density were obtained at (1300°C, 3YSB-YSZ), (1200°C, 5YSB-YSZ), (1100°C, 5YSB-YSZ), and (1100°C, 10YSB-YSZ). The composite ceramic with a YSB doping level of 5 mol% and a sintering temperature of 1100°C achieved the highest density, reaching 97.6%. However, the density of the sintered samples decreased with increasing YSB content. This is because YSB has a low melting point. During high-temperature sintering, it melts into a liquid phase. As a liquid-phase sintering aid, it enhances the sintering activity of the grains, lowers the sintering temperature, and accelerates the densification process. However, some of the molten YSB permeates downwards into the interstices of the green body, while some evaporates upwards, leaving pores in the composite ceramic, which has a decisive influence on the density of the composite ceramic. When YSB is excessive in the composite ceramic, volatilization of YSB becomes the primary process. Consequently, as the YSB content increases, the relative density of the composite ceramic decreases continuously. Therefore, there is an optimal range for the molar content of YSB in YSB-YSZ composite ceramics. The optimal doping level is 5 mol% when sintered at 1100°C and 1200°C, and 3 mol% when sintered at 1300°C.

[0154] At sintering temperatures of 1100°C and 1200°C, the flexural strength first increases and then decreases with increasing YSB doping levels. Its flexural strength is correlated with density. It can be found that the flexural strength at each sintering temperature and at different YSB doping levels is closely related to its density, with the highest density corresponding to the maximum flexural strength. The flexural strengths of pure YSZ samples sintered at 1100°C, 1200°C, and 1300°C were 170 MPa, 168 MPa, and 165 MPa, respectively. With the exception of the sample sintered at 1100°C, where the flexural strength was slightly lower than that of pure YSZ, the flexural strengths of YSB-YSZ sintered at 1100°C and 1200°C were higher than those of pure YSZ. This suggests that the appropriate doping of YSB into YSZ can improve flexural strength and enhance mechanical stability. YSB affects the flexural strength of YSZ in two main ways: first, YSB dissolves into the YSZ lattice, causing lattice distortion and enhancing flexural strength; second, after sintering, YSB exists between the grain boundaries of the YSZ, acting as a pinning force. In summary, the optimal composite ceramic is achieved at a sintering temperature of 1100°C and a YSB doping level of 5 mol%.

[0155] Those skilled in the art will appreciate that the features described in the various embodiments of this application may be combined and / or coupled in various ways, even if such combinations or couplings are not explicitly described in this application. In particular, the features described in the various embodiments of this application may be combined and / or coupled in various ways without departing from the spirit and teachings of this application. All such combinations and / or couplings fall within the scope of this application.

[0156] The embodiments of the present application have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present application. Although each embodiment has been described separately above, this does not mean that the measures in each embodiment cannot be advantageously used in combination. Without departing from the scope of the present application, those skilled in the art may make various substitutions and modifications, and these substitutions and modifications should all fall within the scope of the present application.

Claims

1. A composite powder, characterized in that: The composite powder includes a second material doped with a first material, wherein the first material is a composite material formed by solid-dissolving yttrium oxide in a bismuth oxide lattice, and the second material is a composite material formed by solid-dissolving yttrium oxide in a zirconium oxide lattice.

2. The composite powder according to claim 1, characterized in that In the composite powder, the molar ratio of the first material to the second material is 1:99 to 1:4; In the composite powder, the molar ratio of yttrium element, bismuth element and zirconium element is (2-180): (5-100): (1440-1820); In the first material, the molar ratio of yttrium element to bismuth element is (1-2): (2-3); In the second material, the molar content of yttrium oxide is 5% to 10%.

3. The composite powder according to claim 1 or 2, characterized in that The size of the composite powder is nanometer level.

4. A method for preparing the composite powder according to any one of claims 1 to 3, characterized in that: The preparation method comprises: mixing the second material with the first mixed liquid to obtain an oil phase suspension, wherein the first mixed liquid is a mixture of cyclohexane, a surfactant, and n-hexanol; adding a second mixed liquid to the suspension and continuously stirring to form a water-in-oil microemulsion, wherein the second mixed liquid is a nitric acid solution of bismuth nitrate and yttrium nitrate; Adjusting the pH of the microemulsion to 9.5-10.5, stirring, filtering, and washing to obtain a precursor; The precursor is calcined to obtain composite powder.

5. The preparation method according to claim 4, characterized in that The temperature of the first mixed solution is 35°C to 45°C; The temperature of the suspension is 35°C to 45°C; The surfactant includes at least one of Triton X-100, polyethylene glycol, and polyvinyl pyrrolidone; In the first mixed liquid, the molar ratio of the cyclohexane, the surfactant and the n-hexanol is (6-8):(2-4):(1-3).

6. The preparation method according to claim 4 or 5, characterized in that The temperature of the second mixed liquid is 35° C. to 45° C.; In the second mixed solution, the total concentration of the bismuth nitrate and the yttrium nitrate is 2-3 mol / L; In the second mixed solution, the concentration of nitric acid is 61wt%~75wt%; The temperature of the microemulsion is 35°C to 45°C; The calcination temperature is 500° C. to 700° C., and the calcination time is 1 to 2 hours.

7. A composite ceramic, characterized in that: The composite ceramic is formed by sintering raw materials including composite powder at 1100° C. to 1300° C., and the composite powder is the composite powder according to any one of claims 1 to 3.

8. The composite ceramic according to claim 7, characterized in that The composite ceramic includes lattice oxygen and vacancy oxygen, and the content of the vacancy oxygen is not less than 55% based on the total amount of the lattice oxygen and the vacancy oxygen; In the composite ceramic, the first material is at least partially solid-solved in the crystal lattice of the second material.

9. A method for preparing a composite ceramic, characterized in that: The following steps are involved: The composite powder, the binder and the water are uniformly mixed, granulated, ground and sieved to obtain composite particles, wherein the composite powder is the composite powder according to any one of claims 1 to 3; Pressing the composite particles at 20-30 MPa to obtain a formed blank; The molded blank is sintered at 1100° C. to 1300° C. to obtain a composite ceramic.

10. A server, characterized in that: The server comprises the composite ceramic according to claim 7 or 8 or the composite ceramic produced by the method according to claim 9.

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