Zirconium oxide-based ceramic with high ionic conductivity and preparation method thereof

Abstract

The invention provides high-ionic-conductivity zirconia-based ceramic and a preparation method thereof, and belongs to the technical field of special ceramic preparation. According to the invention, co-doping of Lu < 3 + > and Sc < 3 + > is utilized, oxygen vacancies are introduced through charge change, and more channels are provided for migration of oxygen ions, so that the ionic conductivity of the material is improved; the ionic radiuses of Lu < 3 + > and Sc < 3 + > are close to those of Zr < 4 + > in zirconium oxide, a solid solution structure formed after doping is relatively stable and does not cause obvious lattice distortion, the stable solid solution structure reduces the activation energy of oxygen ion migration and further promotes the improvement of ionic conductivity, and the stable solid solution structure also improves the high-temperature stability of the material; the material still has high ionic conductivity in a high-temperature environment; by controlling the doping amount, the ion conductivity is improved, and meanwhile it is avoided that due to the too high doping amount, lattice distortion is aggravated, oxygen ion movement is hindered, and the ion conductivity is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of special ceramic preparation, and in particular relates to a high ionic conductivity zirconia-based ceramic and a preparation method thereof. Background Art

[0002] With growing awareness of environmental protection, the automotive industry is increasingly demanding stricter standards for exhaust emissions. As a key tool for monitoring and controlling exhaust emissions, oxygen sensors are experiencing rapidly growing market demand. Solid electrolytes, with their exceptional gas-sensing properties resulting from their high ionic conductivity, thermal stability at high temperatures, and excellent corrosion resistance, directly enhance the sensor's operating temperature range and overall performance, making them an indispensable component in oxygen sensors.

[0003] Zirconia-based solid electrolytes are widely used in high-temperature oxygen sensors due to their thermal stability and high cost-effectiveness. However, their low ionic conductivity at high temperatures limits their practical application, resulting in insensitive gas monitoring.

[0004] Currently, there are studies exploring the use of low-cost dopants such as Lu 3+ or Sc 3+ The ionic conductivity of LuSZ has been improved, but it can only reach 0.045S / cm, which is still not enough to meet the needs of practical applications. 3+ The ionic radius of Zr 4+ The radius of ScSZ is similar, and the effect of improving conductivity is the most significant. However, the structure of ScSZ is not stable enough at high temperature (900℃). When operating in a high temperature environment, the conductivity decreases due to structural changes. Therefore, ScSZ is only suitable for low temperature environments. Summary of the Invention

[0005] The present invention aims to provide a high ionic conductivity zirconia-based ceramic and a preparation method thereof. The high ionic conductivity zirconia-based ceramic provided by the present invention has a stable phase structure and still has high ionic conductivity at high temperatures.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a high-ionic conductivity zirconia-based ceramic. The high-ionic conductivity zirconia-based ceramic is a scandium-lutetium co-doped zirconia ceramic. Calculated by mole percentage, the scandium doping amount in the scandium-lutetium co-doped zirconia ceramic is 0.5-2.5%, and the lutetium doping amount is 4-5%.

[0008] Preferably, the high ionic conductivity zirconia-based ceramic is a tetragonal zirconia-based ceramic.

[0009] The present invention also provides a method for preparing the high ionic conductivity zirconia-based ceramics described in the above technical solution, comprising the following steps:

[0010] (1) mixing zirconium oxide, lutetium oxide, and scandium oxide and then performing a first ball milling to obtain a mixed powder;

[0011] (2) pre-calcining the mixed powder obtained in step (1) and then performing a second ball milling to obtain pre-calcined powder;

[0012] (3) mixing the pre-fired powder obtained in step (2) with a binder and then pressing and molding the mixture to obtain a ceramic green body;

[0013] (4) Debinding and sintering the ceramic green body obtained in step (3) in sequence to obtain a zirconia-based ceramic with high ionic conductivity.

[0014] Preferably, the pre-firing temperature in step (2) is 1000-1200° C., and the holding time is 2-4 hours.

[0015] Preferably, the heating rate of the pre-calcination is 4-6°C / min.

[0016] Preferably, the debinding temperature in step (4) is 550-650°C.

[0017] Preferably, the rate of heating to the debinding temperature is 0.4-0.6° C. / min.

[0018] Preferably, the sintering temperature in step (4) is 1350-1500° C., and the holding time is 3-6 hours.

[0019] Preferably, the sintering temperature is increased in stages: the temperature is increased to 950-1000° C. at a heating rate of 4-6° C. / min, and then the temperature is increased to the sintering temperature at a heating rate of 1.5-2.5° C. / min.

[0020] Preferably, the binder in step (3) is an 8-10 wt% polyvinyl alcohol aqueous solution.

[0021] The present invention provides a high ionic conductivity zirconia-based ceramic, wherein the high ionic conductivity zirconia-based ceramic is a scandium-lutetium co-doped zirconia ceramic, wherein the scandium doping amount in the scandium-lutetium co-doped zirconia ceramic is 0.5-2.5% and the lutetium doping amount is 4-5%. 3+ and Sc 3+ The co-doping of Lu and Lu introduces oxygen vacancies through charge changes, providing more channels for the migration of oxygen ions, thereby improving the ionic conductivity of the material; 3+ and Sc 3+The ionic radius of Zr in zirconia 4+ The solid solution structure formed after doping is relatively stable and does not cause significant lattice distortion. This stable solid solution structure reduces the activation energy of oxygen ion migration, further promoting the improvement of ionic conductivity. In addition, the stable solid solution structure also improves the high-temperature stability of the material, so that the material still has high ionic conductivity in a high-temperature environment. By controlling the doping amount of lutetium and scandium, while improving the ionic conductivity, it is avoided that excessive doping will lead to increased lattice distortion, hindering the movement of oxygen ions, and causing a decrease in ionic conductivity. The results of the examples show that the ionic conductivity of the high-ionic conductivity zirconia-based ceramics provided by the present invention is 0.058-0.065 S / cm at 900°C. DETAILED DESCRIPTION

[0022] All raw materials of the present invention are not particularly limited in their sources and can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.

[0023] There is no particular limitation on the purity of all raw materials in the present invention, and high-purity raw materials are preferably used in the present invention.

[0024] The present invention provides a high-ionic conductivity zirconia-based ceramic. The high-ionic conductivity zirconia-based ceramic is a scandium-lutetium co-doped zirconia ceramic. Calculated by mole percentage, the scandium doping amount in the scandium-lutetium co-doped zirconia ceramic is 0.5-2.5%, and the lutetium doping amount is 4-5%.

[0025] In the present invention, the scandium doping amount in the scandium-lutetium co-doped zirconia ceramic is 0.5-2.5% by mole percentage, preferably 0.5-1.5%. In one embodiment of the present invention, the scandium doping amount can be 0.5%, 1%, 1.5%, 2%, or 2.5%. In another embodiment, the lutetium doping amount in the scandium-lutetium co-doped zirconia ceramic is 4-5% by mole percentage, preferably 4.3-4.7%. In another embodiment, the lutetium doping amount can be 4.2%, 4.4%, 4.55%, 4.8%, or 4.9%. Scandium-lutetium co-doped zirconia ceramics doped with scandium and lutetium within the above ranges can form a stable solid solution, improving the high-temperature stability of the material. This also avoids excessive doping that can lead to increased lattice distortion and decreased ionic conductivity.

[0026] In the present invention, the high ionic conductivity zirconia-based ceramic is preferably a tetragonal zirconia-based ceramic, which has higher strength and toughness than cubic zirconia-based ceramics.

[0027] The present invention utilizes Lu 3+ and Sc 3+The co-doping of Lu and Lu introduces oxygen vacancies through charge changes, providing more channels for the migration of oxygen ions, thereby improving the ionic conductivity of the material; 3+ and Sc 3+ The ionic radius of Zr in zirconia 4+ The solid solution structure formed after doping is relatively stable and will not cause obvious lattice distortion. This stable solid solution structure reduces the activation energy of oxygen ion migration, further promoting the improvement of ionic conductivity. Moreover, the stable solid solution structure also improves the high-temperature stability of the material, so that the material still has high ionic conductivity in a high-temperature environment. By controlling the doping amount of lutetium and scandium, while improving the ionic conductivity, it is avoided that excessive doping amount will lead to aggravated lattice distortion, hinder the movement of oxygen ions, and cause a decrease in ionic conductivity.

[0028] The present invention also provides a method for preparing the high ionic conductivity zirconia-based ceramics described in the above technical solution, comprising the following steps:

[0029] (1) mixing zirconium oxide, lutetium oxide, and scandium oxide and then performing a first ball milling to obtain a mixed powder;

[0030] (2) pre-calcining the mixed powder obtained in step (1) and then performing a second ball milling to obtain pre-calcined powder;

[0031] (3) mixing the pre-fired powder obtained in step (2) with a binder and then pressing and molding the mixture to obtain a ceramic green body;

[0032] (4) Debinding and sintering the ceramic green body obtained in step (3) in sequence to obtain a zirconia-based ceramic with high ionic conductivity.

[0033] The present invention mixes zirconium oxide, lutetium oxide and scandium oxide and then performs a first ball milling to obtain mixed powder.

[0034] The present invention has no particular requirements on the form of the zirconium oxide, lutetium oxide, and scandium oxide, as long as they can be mixed evenly. As an embodiment of the present invention, the zirconium oxide, lutetium oxide, and scandium oxide can be nano-powders with a particle size of 50 nm and a purity greater than 99.9%.

[0035] The present invention does not particularly limit the specific parameters of the first ball mill, as long as the raw materials can be evenly mixed. As one embodiment of the present invention, the rotation speed of the first ball mill can be 300-400 r / min; the first ball milling time can be 12-24 hours; the ball-to-material ratio of the first ball mill can be (1-1.5):1; the first ball mill can be wet milling, and the ball milling medium can be anhydrous ethanol; and the mass ratio of the raw materials to the ball milling medium can be 1:(1-1.5).

[0036] After the first ball milling is completed, the present invention can perform a first drying on the resulting product to obtain a mixed powder. The present invention does not particularly limit the parameters of the first drying, as long as the ball milling media can be completely removed. In the embodiment of the present invention, the first drying is performed in an oven.

[0037] After obtaining the mixed powder, the present invention pre-sinters the mixed powder and then performs a second ball milling to obtain pre-sintered powder.

[0038] In the present invention, the pre-firing temperature is preferably 1000-1200°C, more preferably 1050-1150°C; as an embodiment of the present invention, the pre-firing temperature may be 1020°C, 1040°C, 1080°C, 1100°C, 1120°C or 1180°C. In the present invention, the holding time at the pre-firing temperature is preferably 2-4h, more preferably 3h. In the present invention, the pre-firing heating rate is preferably 4-6°C / min, more preferably 5°C / min. The pre-firing parameters within the above range are conducive to removing impurities in the raw materials, reducing the shrinkage of the ceramic, and further improving the stability of the ceramic.

[0039] The present invention does not particularly limit the specific parameters of the second ball milling process, as long as the particles can be refined. As one embodiment of the present invention, the second ball milling speed can be 300-400 r / min; the second ball milling time can be 24-48 hours; the ball-to-material ratio of the second ball milling can be (1-1.5):1; the second ball milling can be wet milling, and the ball milling medium can be anhydrous ethanol; and the mass ratio of the raw material to the ball milling medium can be 1:(1-1.5).

[0040] After the second ball milling is completed, the present invention can perform a second drying on the obtained product to obtain a pre-calcined powder. The present invention has no particular limitation on the specific parameters of the second drying, as long as the ball milling media can be completely removed.

[0041] After obtaining the pre-burned powder, the present invention mixes the pre-burned powder with a binder and then presses the mixture to obtain a ceramic green body.

[0042] In the present invention, the mixture of the calcined powder and the binder is preferably granulated before the press molding; the granulation is preferably sieved granulation, and the mesh size of the sieve used for the sieve granulation is preferably 60-100 mesh, more preferably 70-90 mesh. Using a mesh with such a mesh size for sieve granulation is conducive to obtaining a granulated powder with good fluidity.

[0043] In the present invention, the binder is preferably an 8-10 wt% aqueous solution of polyvinyl alcohol. Polyvinyl alcohol aqueous solution is highly viscous, environmentally friendly, easily degreasable, and has good compatibility, further improving the quality of the ceramic greenware. The amount of the binder used is not particularly limited, as long as it can be granulated after mixing with the pre-calcined powder.

[0044] The present invention does not particularly limit the specific method of the compression molding, as long as a ceramic green body can be obtained. As an embodiment of the present invention, the compression molding can be dry pressing molding, the pressure of the dry pressing molding can be 6-10 MPa, the holding time can be 1-4 minutes, and the tableting device can be an electric tablet press.

[0045] After obtaining the ceramic green body, the present invention sequentially performs debinding and sintering on the ceramic green body to obtain a zirconia-based ceramic with high ionic conductivity.

[0046] In the present invention, the binder removal temperature is preferably 550-650°C, more preferably 580-620°C. As one embodiment of the present invention, the binder removal temperature can be 560°C, 570°C, 590°C, 600°C, 620°C, or 640°C. In the present invention, the rate of heating to the binder removal temperature is preferably 0.4-0.6°C / min, more preferably 0.5°C / min. Debinding parameters within this range facilitate binder removal and further improve the stability of the ceramic.

[0047] In the present invention, the sintering temperature is preferably 1350-1500°C, more preferably 1400-1450°C. As an embodiment of the present invention, the sintering temperature may be 1360°C, 1380°C, 1390°C, 1410°C, 1440°C, or 1480°C. Sintering temperatures within this range are conducive to the formation of the tetragonal phase, further improving the strength and toughness of the ceramic.

[0048] In the present invention, the holding time at the sintering temperature is preferably 3 to 6 hours, more preferably 4 to 5 hours. Holding time within the above range is beneficial to further improve the ionic conductivity of the ceramic.

[0049] In the present invention, the sintering temperature is preferably increased in stages. The heating rate to 950-1000°C is preferably 4-6°C / min, more preferably 5°C / min. The heating rate from 950-1000°C to the sintering temperature is preferably 1.5-2.5°C / min, more preferably 2°C / min. This heating method facilitates densification and uniformity of the ceramic, further improving the high-temperature stability of the ceramic.

[0050] The present invention has no special requirements for the devices for pre-firing, debinding and sintering, and conventional devices in the art can be used; the device used in the embodiment of the present invention is a box-type furnace.

[0051] The preparation method provided by the present invention has simple process, low requirements on equipment, stable and controllable product quality, and is conducive to industrial production.

[0052] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0053] Example 1

[0054] A high ionic conductivity zirconia-based ceramic is a scandium and lutetium co-doped zirconia ceramic, wherein the doping amount of scandium is 0.5 mol%, and the doping amount of lutetium is 4.55 mol%, and is recorded as 0.5Sc4.55LuSZ ceramic.

[0055] The preparation method is as follows:

[0056] 1.08 g of scandium oxide powder, 28.40 g of lutetium oxide powder, 183.52 g of zirconium oxide powder and 319.5 g of anhydrous ethanol were first ball milled at a material-to-ball ratio of 1:1.5 at a speed of 300 r / min for 24 hours. The slurry was taken out and placed in an oven to dry thoroughly.

[0057] The dried powder was placed in a box furnace and heated to 1100°C at a rate of 5°C / min and kept at this temperature for 2 hours to obtain zirconium oxide powder doped with 0.5 mol% scandium oxide and 4.55 mol% lutetium oxide, which was designated as 0.5Sc4.55LuSZ pre-calcined powder. The pre-calcined powder was mixed with anhydrous ethanol and subjected to a second ball milling for 24 hours before drying.

[0058] The powder was fully mixed with 8 wt% of polyvinyl alcohol binder and granulated through a 60-mesh sieve to obtain granulated powder with uniform particle size and good fluidity; and then the ceramic green body was obtained by maintaining the pressure of 6 MPa on an electric tablet press for 1 minute.

[0059] The green body was placed in a box furnace and heated to 650°C at a rate of 0.5°C / min for debinding. The debinded green body was then heated to 1000°C at a rate of 5°C / min, and then to 1350°C at a rate of 2°C / min, and kept at this temperature for 5 hours to obtain 0.5Sc4.55LuSZ ceramics.

[0060] The relative density of the ceramic was tested by the drainage method, its ionic conductivity was tested by the flat electrode method, and its flexural strength was tested by GB / T6569-2006. The final test results were as follows: the relative density of the 0.5Sc4.55LuSZ ceramic prepared in this embodiment was 98.3%, the ionic conductivity of the 0.5Sc4.55LuSZ ceramic was 0.060S / cm at a test temperature of 900°C, the flexural strength was 203±9MPa, and the hardness was 12.16±0.23GPa.

[0061] Example 2

[0062] A high ionic conductivity zirconia-based ceramic is a scandium and lutetium co-doped zirconia ceramic, wherein the doping amount of scandium is 1 mol%, and the doping amount of lutetium is 4.55 mol%, and is recorded as 1Sc4.55LuSZ ceramic.

[0063] The preparation method is as follows:

[0064] 2.08 g of scandium oxide powder, 27.32 g of lutetium oxide powder, 175.60 g of zirconium oxide powder and 308 g of anhydrous ethanol were first ball milled at a material-to-ball ratio of 1:1.5 at a speed of 400 r / min for 24 hours. The slurry was taken out and placed in an oven to dry thoroughly.

[0065] The dried powder was placed in a box furnace and heated to 1100°C at a rate of 5°C / min and kept at that temperature for 4 hours to obtain zirconium oxide powder doped with 1 mol% scandium oxide and 4.55 mol% lutetium oxide, which was recorded as 1Sc4.55LuSZ pre-calcined powder. The pre-calcined powder was mixed with anhydrous ethanol and ball-milled for a second time for 18 hours before drying.

[0066] The powder was fully mixed with 8 wt% of polyvinyl alcohol binder and granulated through a 60-mesh sieve to obtain granulated powder with uniform particle size and good fluidity; then, the powder was pressed under a pressure of 9 MPa on an electric tablet press for 1 minute to obtain a ceramic green body;

[0067] The green body was placed in a box furnace and heated to 550°C at a rate of 0.5°C / min for debinding. The debinded green body was then heated to 1200°C at a rate of 5°C / min, and then to 1500°C at a rate of 2°C / min, and kept at this temperature for 5 hours to obtain 1Sc4.55LuSZ ceramics.

[0068] The relative density of the ceramic was tested by the drainage method, its ionic conductivity was tested by the flat electrode method, and its flexural strength was tested by GB / T6569-2006. The final test results were as follows: the relative density of the 1Sc4.55LuSZ ceramic prepared in this embodiment was 98.2%, the ionic conductivity of the 1Sc4.55LuSZ ceramic was 0.064 S / cm at a test temperature of 900°C, the flexural strength was 233±14 MPa, and the hardness value was 13.87±0.49 GPa.

[0069] Example 3

[0070] A high ionic conductivity zirconia-based ceramic is a scandium and lutetium co-doped zirconia ceramic, wherein the doping amount of scandium is 1.5 mol%, and the doping amount of lutetium is 4.55 mol%, and is recorded as 1.5Sc4.55LuSZ ceramic.

[0071] The preparation method is as follows:

[0072] 3.04 g of scandium oxide powder, 26.64 g of lutetium oxide powder, 170.32 g of zirconium oxide powder and 300 g of anhydrous ethanol were first ball milled at a material-to-ball ratio of 1:1.5 at a speed of 324 r / min for 24 hours, and the slurry was taken out and placed in an oven to dry thoroughly;

[0073] The dried powder was placed in a box furnace and heated to 1100°C at a rate of 5°C / min and kept at this temperature for 2 hours to obtain zirconium oxide powder doped with 1.5 mol% scandium oxide and 4.55 mol% lutetium oxide, which was designated as 1.5Sc4.55LuSZ pre-calcined powder. The pre-calcined powder was mixed with anhydrous ethanol and subjected to a second ball milling for 24 hours before drying.

[0074] The powder was fully mixed with 8 wt% of polyvinyl alcohol binder and granulated through a 60-mesh sieve to obtain granulated powder with uniform particle size and good fluidity; and then the ceramic green body was obtained by maintaining the pressure of 6 MPa on an electric tablet press for 1 minute.

[0075] The green body was placed in a box furnace and heated to 650°C at a rate of 0.5°C / min for debinding. The debinded green body was then heated to 1000°C at a rate of 5°C / min, and then to 1400°C at a rate of 2°C / min, and kept at this temperature for 5 hours to obtain 1.5Sc4.55LuSZ ceramics.

[0076] The relative density of the ceramic was tested by the drainage method, its ionic conductivity was tested by the flat electrode method, and its flexural strength was tested according to GB / T6569-2006. The final test results were as follows: the relative density of the 1.5Sc4.55LuSZ ceramic prepared in this embodiment was 98.7%, the ionic conductivity of the 1.5Sc4.55LuSZ ceramic was 0.062 S / cm at a test temperature of 900°C, the flexural strength was 212±17 MPa, and the hardness was 12.67±0.32 GPa.

[0077] Example 4

[0078] A high ionic conductivity zirconia-based ceramic is a scandium and lutetium co-doped zirconia ceramic, wherein the doping amount of scandium is 2 mol%, and the doping amount of lutetium is 4.55 mol%, and is recorded as 2Sc4.55LuSZ ceramic.

[0079] The preparation method is as follows:

[0080] 4.0 g of scandium oxide powder, 26.22 g of lutetium oxide powder, 166.78 g of zirconium oxide powder and 296 g of anhydrous ethanol were first ball milled at a material-to-ball ratio of 1:1.5 at a speed of 300 r / min for 24 hours, and the slurry was taken out and placed in an oven to dry thoroughly;

[0081] The dried powder was placed in a box furnace and heated to 1100°C at a rate of 5°C / min and kept at this temperature for 2 hours to obtain zirconium oxide powder doped with 2 mol% scandium oxide and 4.55 mol% lutetium oxide, which was designated as 2Sc4.55LuSZ pre-calcined powder. The pre-calcined powder was mixed with anhydrous ethanol and subjected to a second ball milling for 24 hours before drying.

[0082] The powder was fully mixed with 8 wt% of polyvinyl alcohol binder and granulated through a 60-mesh sieve to obtain granulated powder with uniform particle size and good fluidity; and then the ceramic green body was obtained by maintaining the pressure of 6 MPa on an electric tablet press for 1 minute.

[0083] The green body was placed in a box furnace and heated to 650°C at a rate of 0.5°C / min for debinding. The debinded green body was then heated to 1000°C at a rate of 5°C / min, and then to 1350°C at a rate of 2°C / min, and kept at this temperature for 5 hours to obtain 2Sc4.55LuSZ ceramics.

[0084] The relative density of the ceramic was tested by the drainage method, its ionic conductivity was tested by the flat electrode method, and its flexural strength was tested by GB / T6569-2006. The final test results were as follows: the relative density of the 2Sc4.55LuSZ ceramic prepared in this embodiment was 98.5%, the ionic conductivity of the 2Sc4.55LuSZ ceramic was 0.059 S / cm at a test temperature of 900°C, the flexural strength was 219±11 MPa, and the hardness value was 11.82±1.1 GPa.

[0085] Example 5

[0086] A high ionic conductivity zirconia-based ceramic is a scandium and lutetium co-doped zirconia ceramic, wherein the doping amount of scandium is 2.5 mol%, and the doping amount of lutetium is 4.55 mol%, and is recorded as 2.5Sc4.55LuSZ ceramic.

[0087] The preparation method is as follows:

[0088] 5.05 g of scandium oxide powder, 26.54 g of lutetium oxide powder, 167.90 g of zirconium oxide powder and 300 g of anhydrous ethanol were first ball milled at a material-to-ball ratio of 1:1.5 at a speed of 350 r / min for 24 hours, and the slurry was taken out and placed in an oven to dry thoroughly;

[0089] The dried powder was placed in a box furnace and heated to 1100°C at a rate of 5°C / min and kept at this temperature for 2 hours to obtain zirconium oxide powder doped with 2.5 mol% scandium oxide and 4.55 mol% lutetium oxide, which was designated as 2.5Sc4.55LuSZ pre-calcined powder. The pre-calcined powder was mixed with anhydrous ethanol and subjected to a second ball milling for 24 hours before drying.

[0090] The powder was fully mixed with 8 wt% of polyvinyl alcohol binder and granulated through a 60-mesh sieve to obtain granulated powder with uniform particle size and good fluidity; and then the ceramic green body was obtained by maintaining the pressure of 8 MPa on an electric tablet press for 1 minute.

[0091] The green body was placed in a box furnace and heated to 650°C at a rate of 0.5°C / min for debinding. The debinded green body was then heated to 1000°C at a rate of 5°C / min, and then to 1350°C at a rate of 2°C / min, and kept at this temperature for 5 hours to obtain 2.5Sc4.55LuSZ ceramics.

[0092] The relative density of the ceramic was tested by the drainage method, its ionic conductivity was tested by the flat electrode method, and its flexural strength was tested by GB / T6569-2006. The final test results were as follows: the relative density of the 2.5Sc4.55LuSZ ceramic prepared in this embodiment was 98.7%, the ionic conductivity of the 2.5Sc4.55LuSZ ceramic was 0.058 S / cm at a test temperature of 900°C, the flexural strength was 201±9 MPa, and the hardness was 10.87±0.72 GPa.

[0093] Comparative Example 1

[0094] A zirconia-based ceramic is a lutetium-doped zirconia ceramic, wherein the doping amount of lutetium is 4.55 mol%, and is recorded as 4.55LuSZ ceramic.

[0095] The preparation method is as follows:

[0096] 26.68 g of lutetium oxide powder, 173.31 g of zirconium oxide powder and 300 g of anhydrous ethanol were first ball milled at a material-to-ball ratio of 1:1.5 at a speed of 300 r / min for 24 hours. The slurry was taken out and placed in an oven to dry thoroughly.

[0097] The dried powder was placed in a box furnace and heated to 1100°C at a rate of 5°C / min and kept at this temperature for 2 hours to obtain zirconium oxide powder doped with 4.55 mol% lutetium oxide, which was designated as 4.55LuSZ pre-calcined powder. The pre-calcined powder was mixed with anhydrous ethanol and ball-milled for a second time for 24 hours before drying.

[0098] The powder was fully mixed with 8 wt% of polyvinyl alcohol binder and granulated through a 60-mesh sieve to obtain granulated powder with uniform particle size and good fluidity; and then the ceramic green body was obtained by maintaining the pressure of 6 MPa on an electric tablet press for 1 minute.

[0099] The green body was placed in a box furnace and heated to 600°C at a rate of 0.5°C / min for debinding. The debinded green body was then heated to 1000°C at a rate of 5°C / min, and then to 1400°C at a rate of 2°C / min, and kept at this temperature for 5 hours to obtain 4.55LuSZ ceramics.

[0100] The relative density of the ceramic was tested by the drainage method, its ionic conductivity was tested by the flat electrode method, and its flexural strength was tested by GB / T6569-2006. The final test results were: the relative density of the 4.55LuSZ ceramic prepared in this comparative example was 98.6%, the ionic conductivity of the 4.55LuSZ ceramic was 0.045S / cm at a test temperature of 900°C, the flexural strength was 196±11MPa, and the hardness value was 9.87±0.71GPa.

[0101] Comparative Example 2

[0102] A zirconia-based ceramic is a scandium-doped zirconia ceramic, wherein the doping amount of scandium is 4.55 mol%, and is recorded as 4.55ScSZ ceramic.

[0103] The preparation method is as follows:

[0104] 10.13 g of scandium oxide powder, 189.87 g of zirconium oxide powder and 300 g of anhydrous ethanol were first ball milled at a material-to-ball ratio of 1:1.5 at a speed of 400 r / min for 24 hours, and the slurry was taken out and placed in an oven to dry thoroughly;

[0105] The dried powder was placed in a box furnace and heated to 1100°C at a rate of 5°C / min and kept at that temperature for 2 hours to obtain zirconium oxide powder doped with 4.55 mol% of scandium oxide, which was recorded as 4.55ScSZ pre-calcined powder. The pre-calcined powder was mixed with anhydrous ethanol and ball-milled for a second time for 24 hours before drying.

[0106] The powder was fully mixed with 8 wt% of polyvinyl alcohol binder and granulated through a 60-mesh sieve to obtain granulated powder with uniform particle size and good fluidity; and then the ceramic green body was obtained by maintaining the pressure of 7 MPa on an electric tablet press for 2 minutes.

[0107] The green body was placed in a box furnace and heated to 560°C at a rate of 0.5°C / min for debinding. The debinded green body was then heated to 1000°C at a rate of 5°C / min, and then to 1500°C at a rate of 2°C / min, and kept at this temperature for 5 hours to obtain 4.55ScSZ ceramics.

[0108] The relative density of the ceramic was tested by the drainage method, its ionic conductivity was tested by the flat electrode method, and its flexural strength was tested by GB / T6569-2006. The final test results were: the relative density of the 4.55ScSZ ceramic prepared in this comparative example was 97.7%, the ionic conductivity of the 4.55ScSZ ceramic was 0.051S / cm at a test temperature of 900°C, the flexural strength was 193±18MPa, and the hardness value was 11.21±0.66Gpa.

[0109] Comparative Example 3

[0110] A zirconia-based ceramic is a scandium- and lutetium-co-doped zirconia ceramic, wherein the doping amount of scandium is 3 mol%, and the doping amount of lutetium is 4.55 mol%, and is recorded as 3Sc4.55LuSZ ceramic.

[0111] The preparation method is as follows:

[0112] 6.08 g of scandium oxide powder, 26.59 g of lutetium oxide powder, 167.33 g of zirconium oxide powder and 300 g of anhydrous ethanol were first ball milled at a material-to-ball ratio of 1:1.5 at a speed of 300 r / min for 24 hours, and the slurry was taken out and placed in an oven to dry thoroughly;

[0113] The dried powder was placed in a box furnace and heated to 1100°C at a rate of 5°C / min and kept at this temperature for 2 hours to obtain zirconium oxide powder doped with 3 mol% scandium oxide and 4.55 mol% lutetium oxide, which was designated as 3Sc4.55LuSZ calcined powder. The calcined powder was mixed with anhydrous ethanol and subjected to a second ball milling for 24 hours before drying.

[0114] The powder was fully mixed with 8 wt% of polyvinyl alcohol binder and granulated through a 60-mesh sieve to obtain granulated powder with uniform particle size and good fluidity; and then the ceramic green body was obtained by maintaining the pressure of 6 MPa on an electric tablet press for 1 minute.

[0115] The green body was placed in a box furnace and heated to 650°C at a rate of 0.5°C / min for debinding. The debinded green body was then heated to 1000°C at a rate of 5°C / min, and then to 1450°C at a rate of 2°C / min, and kept at this temperature for 5 hours to obtain 3Sc4.55LuSZ ceramics.

[0116] The relative density of the ceramic was tested by the drainage method, its ionic conductivity was tested by the flat electrode method, and its flexural strength was tested by GB / T6569-2006. The final test results were: the relative density of the 3Sc4.55LuSZ ceramic prepared in this comparative example was 97.4%, the ionic conductivity of the 3Sc4.55LuSZ ceramic was 0.048S / cm at a test temperature of 900°C, the flexural strength was 172±15MPa, and the hardness value was 9.91±0.87Gpa.

[0117] It can be seen from the examples and comparative examples 1 and 2 that the present invention improves the flexural strength, hardness and ionic conductivity of zirconia-based ceramics at 900°C through scandium-lutetium co-doping; it can be seen from the examples and comparative example 3 that when the doping amount of scandium is too much, the ionic conductivity, flexural strength and hardness of the ceramics will be reduced.

[0118] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A high ionic conductivity zirconia-based ceramic, wherein the high ionic conductivity zirconia-based ceramic is a scandium-lutetium co-doped zirconia ceramic, wherein, in terms of molar percentage, the scandium doping amount in the scandium-lutetium co-doped zirconia ceramic is 0.5-2.5%, and the lutetium doping amount is 4-5%.

2. The high ionic conductivity zirconia-based ceramic according to claim 1, characterized in that: The high ionic conductivity zirconia-based ceramic is a tetragonal zirconia-based ceramic.

3. The method for preparing the high ionic conductivity zirconia-based ceramic according to claim 1 or 2, comprising the following steps: (1) mixing zirconium oxide, lutetium oxide, and scandium oxide and then performing a first ball milling to obtain a mixed powder; (2) pre-calcining the mixed powder obtained in step (1) and then performing a second ball milling to obtain pre-calcined powder; (3) mixing the pre-fired powder obtained in step (2) with a binder and then pressing and molding the mixture to obtain a ceramic green body; (4) Debinding and sintering the ceramic green body obtained in step (3) in sequence to obtain a zirconia-based ceramic with high ionic conductivity.

4. The preparation method according to claim 3, characterized in that The pre-firing temperature in step (2) is 1000-1200° C., and the holding time is 2-4 hours.

5. The preparation method according to claim 4, characterized in that The heating rate of the pre-calcination is 4-6°C / min.

6. The preparation method according to claim 3, characterized in that The debinding temperature in step (4) is 550-650°C.

7. The preparation method according to claim 6, characterized in that The rate of heating to the debinding temperature is 0.4-0.6°C / min.

8. The preparation method according to claim 3, characterized in that The sintering temperature in step (4) is 1350-1500° C., and the holding time is 3-6 hours.

9. The preparation method according to claim 8, characterized in that The sintering temperature is increased in stages: the temperature is increased to 950-1000° C. at a heating rate of 4-6° C. / min, and then the temperature is increased to the sintering temperature at a heating rate of 1.5-2.5° C. / min.

10. The preparation method according to claim 3, characterized in that The binder in step (3) is an 8-10 wt% polyvinyl alcohol aqueous solution.