Preparation method of zirconia fiber toughened yttrium oxide ceramic

Abstract

The invention discloses a preparation method of zirconia fiber toughened yttrium oxide ceramic. The preparation method comprises the following steps: preparing zirconia fiber-yttrium oxide mixed powder by adopting a spray granulation technology; mixing the mixed powder with a binder and a solvent to prepare slurry with high solid content; and preparing the slurry into a green body through injection molding, drying, dumping and sintering to form the zirconia fiber toughened yttrium oxide ceramic. By introducing the zirconium oxide fiber, the bending strength and the fracture toughness of the yttrium oxide ceramic can be remarkably improved, and crack propagation can be effectively prevented through good interface bonding of the fiber and a matrix; the composite powder is prepared by spray drying, so that the uniformity and dispersity of the powder can be improved; the novel nano composite material injection molding process can be used for preparing a ceramic structural part with a complex shape, and is high in molding precision and low in defect rate; the preparation process is simple, the production efficiency is high, and the prepared ceramic has the advantages of high strength, high density, good insulativity, high temperature resistance and the like.

Description

Technical Field

[0001] The invention relates to the technical field of inorganic ceramic material preparation, and in particular to a method for preparing zirconium oxide fiber-reinforced yttria ceramics. Background Art

[0002] The microinjection molding technology of nanocomposite materials originates from the demand for high-precision and high-performance micro-parts manufacturing. This technology combines the superior properties of nanomaterials with the high-precision characteristics of microinjection molding. By precisely controlling the dispersion and compounding of nanoparticles in the polymer matrix, as well as parameters such as temperature and pressure during the injection molding process, it can achieve precise control of the size, shape and performance of micro-parts.

[0003] Yttria (Y2O3) ceramics are widely used in aerospace, high-temperature structural parts and optical components due to their high melting point, excellent high-temperature stability, low thermal expansion coefficient and excellent oxidation resistance. However, as a single-phase ceramic, yttria ceramics have low fracture toughness and flexural strength, which limits their further promotion in extreme environments. In order to overcome these problems, researchers have tried to introduce a reinforcing phase to improve the comprehensive performance of yttria ceramics.

[0004] Zirconia (ZrO2) fiber is an ideal choice for toughening yttria ceramics due to its high strength, excellent high temperature performance and stable chemical properties. However, the existing technology has the following shortcomings in the preparation of zirconia fiber reinforced yttria ceramics: the uneven distribution of the reinforcement phase in the matrix leads to local performance degradation; the traditional molding method is difficult to meet the needs of complex-shaped products; and the sintering process is prone to grain growth or pore defects, which affects the density and mechanical properties of the ceramics. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing zirconium oxide fiber-toughened yttria ceramics. The present invention adopts spray drying to prepare composite powders, which can improve the uniformity and dispersibility of the powders and ensure the uniform distribution of zirconium oxide fibers in the yttria matrix. The introduction of zirconium oxide fibers is beneficial to significantly improve the bending strength and fracture toughness of yttria ceramics, and the good interface bonding between the fibers and the matrix can effectively prevent crack propagation. The present invention adopts a new nano-composite material microinjection molding process to overcome the limitations of traditional molding processes, and can prepare ceramic structural parts with complex shapes, with high molding accuracy and low defect rate, providing technical guarantee for industrial production. The preparation process of the present invention is simple and the production efficiency is high. The prepared ceramics can have the advantages of high strength, high density, good insulation and high temperature resistance.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing zirconium oxide fiber-toughened yttria ceramics, characterized in that the material is prepared by the following steps:

[0008] Step a: preparing zirconium oxide fiber-yttria mixed powder by spray granulation technology;

[0009] Step b: mixing the mixed powder with a binder and a solvent to prepare a slurry with a high solid content;

[0010] Step c: preparing a green body by injection molding the slurry;

[0011] Step d: drying, debinding and sintering the green body to form zirconia fiber-reinforced yttria ceramics.

[0012] Preferably, in step a, the zirconium oxide fiber-yttrium oxide mixed powder prepared by spray granulation technology is first mixed with zirconium oxide fiber, yttrium oxide powder, deionized water, a dispersant, and a binder to prepare a mixed slurry, wherein the mass fraction of the zirconium oxide fiber is 5-10% of the total mass of the powder, the mass fraction of yttrium oxide is 90-95% of the total mass of the powder, the dispersant is one or more of ammonium citrate, polyvinyl pyrrolidone, and polyacrylic acid, and the added amount is 0.5-2% of the mass of the powder; the binder is one or more of polyvinyl alcohol, phenolic resin, and sodium carboxymethyl cellulose, and the added amount is 0.1-1.5% of the mass of the powder; the slurry is ultrasonically dispersed for 30-60 minutes, and the slurry solid content is 40-60wt%; the feed temperature of the spray drying is 120-200°C, and the outlet temperature is 100-150°C.

[0013] Preferably, in step b, in the high solid content slurry, the mass fraction of the mixed powder is 70-85%; the binder is one or more of polyvinylidene fluoride resin, polypropylene, and ethylene-vinyl acetate copolymer, and the mass fraction of the binder is 5-15%; the solvent is one or more of pinene alcohol, polyethylene glycol, and ethanol, and the mass fraction of the solvent is 5-20%.

[0014] Preferably, in step c, during injection molding, the slurry injection temperature is 20-50° C., the mold temperature is 40-80° C., and the injection pressure is 50-150 MPa.

[0015] Preferably, in step d, the drying temperature is 80-120°C, and the drying time is 18-24h; the binder removal process is to heat the material to 800°C at a rate of 1-5°C / min in a muffle furnace and keep it warm for 1-2h; the sintering process is to heat the material to 800°C at a rate of 1-5°C / min, keep it warm for 1-2h, and then heat the material to 1780-1850°C at a rate of 1-3°C / min, and keep it warm for 2-5h.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The invention introduces zirconium oxide fiber to significantly improve the bending strength and fracture toughness of yttria ceramics. The good interface bonding between the fiber and the matrix effectively prevents crack propagation.

[0018] (2) The present invention improves the uniformity and dispersibility of the powder by preparing the composite powder through spray drying, ensuring the uniform distribution of the zirconium oxide fiber in the yttria matrix; the step-by-step sintering technology effectively avoids grain growth and pore defects, and prepares a high-density ceramic material.

[0019] (3) The present invention adopts a new nanocomposite material injection molding process to overcome the limitations of traditional molding processes, and can prepare ceramic structural parts with complex shapes, with high molding accuracy and low defect rate, providing technical guarantee for industrial production. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below with reference to specific embodiments.

[0021] Example 1

[0022] a) preparing zirconia fiber-yttrium oxide mixed powder by spray granulation technology: firstly, 5g zirconia fiber, 95g yttrium oxide powder, 150g deionized water, 0.5g dispersant ammonium citrate, and 0.1g binder polyvinyl alcohol were mixed to prepare a mixed slurry, and the slurry was ultrasonically dispersed for 30min and spray granulated. The feed temperature of the spray drying was 120°C and the outlet temperature was 100°C;

[0023] b) mixing 70 g of the mixed powder with 15 g of a binder polyvinylidene fluoride resin and 15 g of pinene alcohol to prepare a slurry with a high solid content;

[0024] c) preparing the slurry into a green body by injection molding: the slurry injection temperature is 20° C., the mold temperature is 40° C., and the injection pressure is 50 MPa;

[0025] d) Drying, debinding and sintering the green body to form zirconia fiber toughened yttria ceramics: drying temperature is 80°C, drying for 24 hours; debinding process is to heat to 800°C at a rate of 1°C / min in a muffle furnace and keep warm for 1 hour; sintering process is: heating to 800°C at a rate of 1°C / min, keeping warm for 1 hour, heating to 1780°C at a rate of 1°C / min, and keeping warm for 2 hours.

[0026] Example 2

[0027] a) preparing zirconia fiber-yttrium oxide mixed powder by spray granulation technology: firstly, 7g zirconia fiber, 93g yttrium oxide powder, 122.22g deionized water, 1g dispersant ammonium citrate, and 0.5g binder polyvinyl alcohol were mixed to prepare a mixed slurry, the slurry was ultrasonically dispersed for 40min, and then spray granulated, the feed temperature of the spray drying was 140°C, and the outlet temperature was 110°C;

[0028] b) mixing 75 g of the mixed powder with 12.5 g of a binder, polypropylene, and 12.5 g of polyethylene glycol to prepare a slurry with a high solid content;

[0029] c) preparing the slurry into a green body by injection molding: the slurry injection temperature is 30° C., the mold temperature is 50° C., and the injection pressure is 80 MPa;

[0030] d) Drying, debinding and sintering the green body to form zirconia fiber toughened yttria ceramics: drying temperature is 90°C, drying for 20 hours; debinding process is to heat to 800°C at a rate of 1.5°C / min in a muffle furnace and keep warm for 2 hours; sintering process is: heating to 800°C at a rate of 1.5°C / min, keeping warm for 2 hours, heating to 1800°C at a rate of 1.5°C / min, keeping warm for 3 hours.

[0031] Example 3

[0032] a) Preparing zirconia fiber-yttrium oxide mixed powder by spray granulation technology: first, 8.5g zirconia fiber, 91.5g yttrium oxide powder, 100g deionized water, 0.5g dispersant ammonium citrate, and 1g binder polyvinyl alcohol were mixed to prepare a mixed slurry, the slurry was ultrasonically dispersed for 50min, and then spray granulated. The feed temperature of the spray drying was 170°C, and the outlet temperature was 140°C;

[0033] b) mixing 80 g of the mixed powder with 10 g of a binder ethylene-vinyl acetate copolymer, 10 g of polyethylene glycol and ethanol to prepare a slurry with a high solid content;

[0034] c) preparing the slurry into a green body by injection molding: the slurry injection temperature is 40° C., the mold temperature is 65° C., and the injection pressure is 120 MPa;

[0035] d) Drying, debinding and sintering the green body to form zirconia fiber toughened yttria ceramics: drying temperature is 100°C, drying for 18 hours; debinding process is to heat to 800°C at a rate of 3°C / min in a muffle furnace and keep warm for 2 hours; sintering process is: heating to 800°C at a rate of 3°C / min, keeping warm for 1.5 hours, heating to 1825°C at a rate of 3°C / min, and keeping warm for 4 hours.

[0036] Example 4

[0037] a) Preparing zirconia fiber-yttrium oxide mixed powder by spray granulation technology: firstly, 10g zirconia fiber, 90g yttrium oxide powder, 66.66g deionized water, 1.5g dispersant ammonium citrate, and 1.5g binder polyvinyl alcohol were mixed to prepare a mixed slurry, and the slurry was ultrasonically dispersed for 60min and spray granulated. The feed temperature of the spray drying was 200°C and the outlet temperature was 150°C;

[0038] b) mixing 85 g of the mixed powder with 5 g of polypropylene and polyvinylidene fluoride resin and 10 g of ethanol to prepare a slurry with a high solid content;

[0039] c) preparing the slurry into a green body by injection molding: the slurry injection temperature is 50° C., the mold temperature is 60° C., and the injection pressure is 130 MPa;

[0040] d) Drying, debinding and sintering the green body to form zirconia fiber toughened yttria ceramics: drying temperature is 120°C, drying for 20 hours; debinding process is to heat to 800°C at a rate of 5°C / min in a muffle furnace and keep warm for 1.5 hours; sintering process is: heating to 800°C at a rate of 5°C / min, keeping warm for 2 hours, heating to 1850°C at a rate of 2.5°C / min, and keeping warm for 3 hours.

[0041] Comparative Example

[0042] a) mixing 80 g of yttrium oxide powder with 11 g of a binder ethylene-vinyl acetate copolymer, 11 g of polyethylene glycol and ethanol to prepare a slurry with a high solid content;

[0043] b) preparing the slurry into a green body by injection molding: the slurry injection temperature is 40° C., the mold temperature is 65° C., and the injection pressure is 120 MPa;

[0044] c) Drying, debinding and sintering the green body to form zirconium oxide fiber-reinforced yttria ceramics: drying temperature is 100°C, drying for 18 hours; debinding process is to heat to 800°C at a rate of 3°C / min in a muffle furnace and keep warm for 2 hours; sintering process is: heating to 800°C at a rate of 3°C / min, keeping warm for 1.5 hours, heating to 1825°C at a rate of 3°C / min, and keeping warm for 4 hours.

[0045] Effect verification:

[0046] The bending strength and toughness of the zirconia fiber toughened yttria ceramic materials obtained in the above Examples 1, 2, 3 and 4 and the yttria ceramics obtained in the comparative example were tested according to the following standards. The test results are shown in Table 1.

[0047] Bending strength test: follow GB / T 6569-2006.

[0048] Toughness test: Single-side notched beam method is adopted, and the testing instrument is an electronic universal testing machine.

[0049] Table 1 Ceramic performance test results obtained in Examples 1-4 and Comparative Examples

[0050] Example Bending strength(MPa) <![CDATA[Toughness (MPa·m 1 / 2 )]]> Example 1 142 4.98 Example 2 145 4.89 Example 3 139 4.89 Example 4 138 4.92 Comparative Example 112 4.65

[0051] As shown in Table 1, the strength of zirconia fiber-toughened yttria ceramics increased from 112MPa to 145MPa, and the toughness increased from 4.65MPa·m 1 / 2 Increased to 4.98MPa·m 1 / 2 As shown above, the strength and toughness are significantly improved, indicating that zirconia fiber-toughened yttria ceramics have higher flexural strength and toughness.

[0052] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for preparing zirconium oxide fiber toughened yttria ceramics, characterized in that: The material is prepared by the following steps: Step a: preparing zirconium oxide fiber-yttria mixed powder by spray granulation technology; Step b: mixing the mixed powder with a binder and a solvent to prepare a slurry with a high solid content; Step c: preparing a green body by injection molding the slurry; Step d: drying, debinding and sintering the green body to form zirconia fiber-reinforced yttria ceramics.

2. The method for preparing a zirconium oxide fiber toughened yttria ceramic according to claim 1, characterized in that: In step a, the zirconium oxide fiber-yttrium oxide mixed powder prepared by spray granulation technology is first mixed with zirconium oxide fiber, yttrium oxide powder, deionized water, a dispersant and a binder to prepare a mixed slurry, wherein the mass fraction of the zirconium oxide fiber is 5-10% of the total mass of the powder, the mass fraction of yttrium oxide is 90-95% of the total mass of the powder, the dispersant is one or more of ammonium citrate, polyvinyl pyrrolidone and polyacrylic acid, and the added amount is 0.5-2% of the mass of the powder; the binder is one or more of polyvinyl alcohol, phenolic resin and sodium carboxymethyl cellulose, and the added amount is 0.1-1.5% of the mass of the powder; the slurry is ultrasonically dispersed for 30-60 minutes, and the solid content of the slurry is 40-60wt%; the feed temperature of the spray drying is 120-200°C, and the outlet temperature is 100-150°C.

3. The method for preparing a zirconium oxide fiber toughened yttria ceramic according to claim 1, characterized in that: In the high solid content slurry in step b, the mass fraction of the mixed powder is 70-85%; the binder is one or more of polyvinylidene fluoride resin, polypropylene, and ethylene-vinyl acetate copolymer, and the mass fraction of the binder is 5-15%; the solvent is one or more of terpineol, polyethylene glycol, and ethanol, and the mass fraction of the solvent is 5-20%.

4. The method for preparing a zirconium oxide fiber toughened yttria ceramic according to claim 1, characterized in that: In step c, during injection molding, the slurry injection temperature is 20-50° C., the mold temperature is 40-80° C., and the injection pressure is 50-150 MPa.

5. The method for preparing a zirconium oxide fiber toughened yttria ceramic according to claim 1, characterized in that: In step d), the drying temperature is 80-120° C. and the drying time is 18-24 hours. The binder removal process is to heat the mixture to 800° C. at a rate of 1-5° C. / min in a muffle furnace and keep the temperature for 1-2 hours. The sintering process is as follows: heating to 800°C at a rate of 1-5°C / min, keeping warm for 1-2h, heating to 1780-1850°C at a rate of 1-3°C / min, keeping warm for 2-5h.