Zirconia-calcium zirconate composite ceramic and preparation method and application thereof

Abstract

This invention provides a zirconia-calcium zirconate composite ceramic, its preparation method, and its application, relating to the field of metal ceramics technology. The preparation method of the zirconia-calcium zirconate composite ceramic includes the following steps: mixing zirconia and calcium carbonate and calcining to obtain zirconia particles coated with calcium zirconate; mixing the calcium zirconate-coated zirconia particles with zirconia, pressing them into shape, and sintering to obtain the zirconia-calcium zirconate composite ceramic. This invention utilizes heating to react zirconia and calcium carbonate to generate calcium zirconate, and the generated calcium zirconate uniformly coats the zirconia particles. The resulting calcium zirconate-coated zirconia particles exhibit excellent performance, comprehensively utilizing the high thermodynamic stability, excellent corrosion resistance, strong temperature resistance, and low susceptibility to polycrystalline transformation of calcium zirconate materials, thus greatly improving the thermal shock resistance of zirconia ceramics. Furthermore, the preparation process is simple, with a short preparation cycle and low cost.

Description

Technical Field

[0001] This invention relates to the field of ceramic technology, and in particular to a zirconium oxide-calcium zirconate composite ceramic, its preparation method, and its application. Background Technology

[0002] High-temperature alloys play a crucial role in modern production, their unique properties enabling them to maintain stable mechanical and chemical properties under extreme environments such as high temperature and high pressure. Due to their excellent high-temperature performance, good mechanical properties, resistance to hot corrosion, and good overall performance, high-temperature alloys hold a pivotal position in aerospace, energy, and chemical industries. However, the widespread application of high-temperature alloys is constrained by their high production costs. Currently, vacuum induction melting is a typical process for the preparation of high-temperature alloys, and crucibles are an indispensable and crucial refractory material in this process. With the development of high-temperature alloys towards higher generations, new challenges arise in the selection of crucible materials and the improvement of structural stability.

[0003] Zirconia ceramics are known to possess the best overall performance in terms of toughness and strength among oxide ceramics. Due to their superior thermal stability and good mechanical properties, zirconia ceramics have been widely used as refractory materials in industrial production in recent years, serving as crucibles for high-temperature alloy melting, and have seen rapid development and application in various fields. However, zirconia has three crystal forms: monoclinic, tetragonal, and cubic. The transformation from tetragonal to monoclinic phase is a martensitic phase transformation, which generates 8% shear strain and 3%–5% volume change. Therefore, the inherent brittleness, low fracture toughness, and low strength of ZrO2 ceramics limit their application range. To improve the overall performance of ZrO2 ceramics and meet market demands, researchers have conducted extensive studies on material composition design, doping modification, and process improvement.

[0004] Calcium zirconate, with its perovskite crystal structure, possesses high thermodynamic stability, excellent corrosion resistance, strong temperature resistance, and is not prone to polycrystalline transformation, making it a potentially advantageous material for crucibles used in high-temperature alloys. Considering the excellent toughness and strength of zirconia ceramics combined with the high thermodynamic stability and resistance to polycrystalline transformation of calcium zirconate, the development of a ZrO2-CaZrO3 composite ceramic for manufacturing crucibles for high-temperature alloy melting is highly promising. Summary of the Invention

[0005] The purpose of this invention is to provide a zirconia-calcium zirconate composite ceramic, its preparation method and application, in order to solve the problem that zirconia ceramics are difficult to meet market demands due to their brittleness, low fracture toughness and low strength.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing zirconium oxide-calcium zirconate composite ceramics, comprising the following steps:

[0008] 1) Zirconia particles coated with calcium zirconate were obtained by calcining a mixture of zirconium oxide and calcium carbonate.

[0009] 2) Zirconia particles coated with calcium zirconate are mixed with zirconium oxide, pressed into shape, and then sintered to obtain zirconium oxide-calcium zirconate composite ceramic.

[0010] Preferably, the mass ratio of zirconium oxide to calcium carbonate in step 1) is 100-110:10-12.

[0011] Preferably, the mixing method in step 1) is ball milling;

[0012] The ball milling speed is 80-200 r / min, the ball milling time is 180-240 min, and the ball-to-material ratio is 1.5-2:1.

[0013] Preferably, the calcination temperature in step 1) is 1400–1600°C and the calcination time is 180–240 min.

[0014] Preferably, the calcination heating program in step 1) is to heat to 1000°C at a rate of 8-10°C / min, and then heat to the calcination temperature at a rate of 3-5°C / min.

[0015] Preferably, in step 2), the mass ratio of the calcium zirconate-coated zirconium oxide particles to zirconium oxide is 0.5 to 1.5:1.

[0016] Preferably, the pressing molding in step 2) includes sequential dry pressing preforming and cold isostatic pressing preforming;

[0017] The pressure of the dry pressing preforming is 50-80 MPa, and the holding time of the dry pressing preforming is 1-3 min;

[0018] The pressure of the cold isostatic pressing preforming is 150-300 MPa, and the holding time of the cold isostatic pressing preforming is 60-90 s.

[0019] Preferably, the sintering temperature in step 2) is 1400–1600°C and the sintering time is 3–4 h.

[0020] This invention provides a zirconium oxide-calcium zirconate composite ceramic prepared by the above preparation method.

[0021] The present invention also provides an application of the aforementioned zirconium oxide-calcium zirconate composite ceramic in high-temperature alloy smelting.

[0022] The present invention has at least the following beneficial effects:

[0023] This invention utilizes heating to react zirconium oxide and calcium carbonate to produce calcium zirconate, which uniformly coats the zirconium oxide particles. The resulting calcium zirconate-coated zirconium oxide particles exhibit excellent properties, comprehensively leveraging the high thermodynamic stability, excellent corrosion resistance, strong temperature resistance, and resistance to polycrystalline transformation of calcium zirconate materials. This significantly improves the thermal shock resistance of zirconium oxide ceramics. Furthermore, the preparation process is simple, has a short cycle time, and is low in cost. Attached Figure Description

[0024] Figure 1 The image shows the XRD pattern of the calcium zirconate-coated zirconium oxide particles prepared in Example 1.

[0025] Figure 2 This is a SEM image of the calcium zirconate-coated zirconium oxide particles prepared in Example 1;

[0026] Figure 3 This is a SEM image of the calcium zirconate-coated zirconium oxide particles prepared in Example 2;

[0027] Figure 4 This is a SEM image of the zirconia particles coated with calcium zirconate prepared in Example 2. Detailed Implementation

[0028] This invention provides a method for preparing zirconium oxide-calcium zirconate composite ceramics, comprising the following steps:

[0029] 1) Zirconia particles coated with calcium zirconate were obtained by calcining a mixture of zirconium oxide and calcium carbonate.

[0030] 2) Zirconia particles coated with calcium zirconate are mixed with zirconium oxide, pressed into shape, and then sintered to obtain zirconium oxide-calcium zirconate composite ceramic.

[0031] In this invention, the mass ratio of zirconium oxide to calcium carbonate in step 1) is 100-110:10-12, preferably 102-108:10.5-11.5, more preferably 104-106:11, and even more preferably 105:11.

[0032] In this invention, the mixing method described in step 1) is ball milling.

[0033] In this invention, the ball milling speed is 80-200 r / min, preferably 100-180 r / min, more preferably 120-160 r / min, and even more preferably 140-150 r / min; the ball milling time is 180-240 min, preferably 190-230 min, and even more preferably 200-220 min; the ball-to-material ratio is 1.5-2:1, preferably 1.6-1.9:1, and even more preferably 1.7-1.8:1.

[0034] In this invention, ethanol is added as a co-solvent during the ball milling process.

[0035] In this invention, after the ball milling and mixing is completed, the powder is further subjected to rotary evaporation and sieving in sequence; the rotary evaporation temperature is 60°C and the rotary evaporation time is 20 min; the sieving is through a 60-mesh sieve.

[0036] In this invention, the calcination temperature in step 1) is 1400-1600℃, preferably 1500-1600℃, more preferably 1550-1600℃, and even more preferably 1600℃; the calcination time is 180-240 min, preferably 190-230 min, and even more preferably 200-220 min.

[0037] In this invention, the calcination heating program in step 1) is to heat to 1000°C at a rate of 8-10°C / min and then heat to the calcination temperature at a rate of 3-5°C / min, preferably at a rate of 8-9°C / min to 1000°C and then heat to the calcination temperature at a rate of 3-4°C / min.

[0038] In this invention, the mass ratio of the calcium zirconate-coated zirconium oxide particles to zirconium oxide in step 2) is 0.5 to 1.5:1, preferably 0.7 to 1.3:1, more preferably 0.8 to 1.2:1, and even more preferably 0.9 to 1:1.

[0039] In this invention, the pressing molding described in step 2) includes sequential dry pressing pre-forming and cold isostatic pressing pre-forming;

[0040] In this invention, the pressure of the dry pressing preforming is 50-80 MPa, preferably 55-75 MPa, more preferably 60-70 MPa, and even more preferably 65 MPa; the holding time of the dry pressing preforming is 1-3 min, preferably 2-3 min.

[0041] In this invention, the pressure of the cold isostatic pressing preforming is 150-300 MPa, preferably 170-280 MPa, more preferably 190-250 MPa, and even more preferably 210-230 MPa; the holding time of the cold isostatic pressing preforming is 60-90 s, preferably 65-85 s, more preferably 70-80 s, and even more preferably 75 s.

[0042] In this invention, the sintering temperature in step 2) is 1400–1600°C, preferably 1430–1580°C, more preferably 1450–1550°C, and even more preferably 1480–1520°C; the sintering time is 120–240 min, preferably 150–210 min, more preferably 170–200 min, and even more preferably 180–190 min.

[0043] This invention provides a zirconium oxide-calcium zirconate composite ceramic prepared by the above preparation method.

[0044] The present invention also provides an application of the aforementioned zirconium oxide-calcium zirconate composite ceramic in high-temperature alloy smelting.

[0045] In this invention, the zirconium oxide-calcium zirconate composite ceramic is preferably used as a crucible in high-temperature alloy smelting.

[0046] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0047] Example 1

[0048] 1) Add 10.8g of zirconium oxide powder and 1.2g of calcium carbonate powder to a wide-mouth bottle and ball mill them using a ball mill. The mass ratio of grinding balls, ethanol and powder is 1.5:1.2:1. The rotation speed is 90r / min and the mixing time is 240min. After ball milling, rotary evaporate at 60℃ for 20min. The powder obtained after rotary evaporation is passed through a 60-mesh sieve to obtain mixed powder.

[0049] 2) Place the mixed powder in a mortar and grind it evenly. Spread the evenly mixed powder evenly in a crucible, then place the crucible in a muffle furnace. After setting the heating and cooling regime, start heating. The heating and cooling regime is as follows: when the temperature is below 1000℃, maintain the heating rate at 8℃ / min. When the temperature rises to 1000℃, adjust the heating rate to maintain 5℃ / min. Raise the temperature to 1600℃ and hold for 180min. After the holding period, when the temperature is above 1000℃, maintain the cooling rate at 5℃ / min. When the temperature drops to 1000℃, adjust the cooling rate to furnace cooling. Record the temperature change during sintering. After cooling to room temperature, turn off the heating. Grind and sieve the obtained particles in sequence to prepare dispersed calcium zirconate-coated zirconia particles.

[0050] 3) 5g of the obtained calcium zirconate-coated zirconium oxide particles were ball-milled with 5g of ordinary zirconium oxide powder (ball-to-material ratio of 1.5:1, rotation speed of 90r / min, ball-milling time of 240min) and then dry-pressed for preforming (70MPa, holding pressure for 90s). The preformed green body was then cold-isostatically pressed for preforming (200MPa, holding pressure for 90s) to obtain a green body. The green body was then conventionally sintered (1500℃, 180min) to prepare ZrO2-CaZrO3 composite ceramic.

[0051] X-ray diffraction (XRD) was performed on the calcium zirconate-coated zirconium oxide particles prepared in this embodiment. The XRD pattern is shown below. Figure 1 As shown, from Figure 1 It can be seen that CaZrO3 was generated in the powder, and the powder is a mixture of CaZrO3 and ZrO2. Figure 2 This is a scanning electron microscope image of the calcium zirconate-coated zirconium oxide particles prepared in this embodiment. Figure 2 It can be seen that the generated CaZrO3 is uniformly coated on the surface of ZrO2 particles.

[0052] Example 2

[0053] 1) Add 10.8g of zirconium oxide powder and 1.2g of calcium carbonate powder to a wide-mouth bottle and ball mill them using a ball mill. The ratio of grinding balls, ethanol and powder is 1.5:1.2:1. The speed is 90r / min and the mixing time is 240min. After ball milling, rotary evaporate at 60℃ for 20min. The powder obtained after rotary evaporation is passed through a 60-mesh sieve to obtain mixed powder.

[0054] 2) Place the mixed powder in a mortar and grind it evenly. Spread the evenly mixed powder evenly in a crucible, then place the crucible in a muffle furnace. After setting the heating and cooling regime, start heating. The heating and cooling regime is as follows: when the temperature is below 1000℃, maintain the heating rate at 8℃ / min. When the temperature rises to 1000℃, adjust the heating rate to maintain 5℃ / min. Heat to 1600℃ and hold for 240min. After the holding period, when the temperature is above 1000℃, maintain the cooling rate at 5℃ / min. When the temperature drops to 1000℃, adjust the heating rate to allow the furnace to cool. Record the temperature changes during sintering. After cooling to room temperature, turn off the heating. Grind and sieve the obtained particles in sequence to prepare dispersed calcium zirconate-coated zirconia particles.

[0055] 3) 5g of the obtained calcium zirconate-coated zirconium oxide particles were ball-milled with 5g of ordinary zirconium oxide powder (ball-to-material ratio of 1.5:1, rotation speed of 90r / min, ball-milling time of 240min) and then dry-pressed for preforming (70MPa, holding pressure for 1.5min). Subsequently, the dry-pressed preform was cold-isostatically pressed for preforming (200MPa, holding pressure for 90s) to obtain a green body. The green body was then microwave-sintered (1500℃, 180min) to prepare ZrO2-CaZrO3 composite ceramic.

[0056] Figure 3 and Figure 4 This is a scanning electron microscope image of the zirconium oxide particles coated with calcium zirconate prepared in this embodiment. It can be seen from the image that ZrO2 and CaCO3 react to generate calcium zirconate, and the generated CaZrO3 is uniformly coated on the ZrO2 particles.

[0057] Example 3

[0058] 1) Add 10g of zirconium oxide powder and 1.1g of calcium carbonate powder to a wide-mouthed bottle and ball mill them using a ball mill. The ratio of grinding balls, ethanol and powder is 1.8:1.5:1. The rotation speed is 120r / min and the mixing time is 180min. After ball milling, rotary evaporate at 60℃ for 20min. The powder obtained after rotary evaporation is passed through a 60-mesh sieve to obtain mixed powder.

[0059] 2) Place the mixed powder in a mortar and grind it evenly. Spread the evenly mixed powder evenly in a crucible, then place the crucible in a muffle furnace. After setting the heating and cooling regime, start heating. The heating and cooling regime is as follows: when the temperature is below 1000℃, maintain the heating rate at 10℃ / min. When the temperature rises to 1000℃, adjust the heating rate to maintain 5℃ / min. Raise the temperature to 1550℃ and hold for 200min. After the holding period, when the temperature is above 1000℃, maintain the cooling rate at 5℃ / min. When the temperature drops to 1000℃, adjust the heating rate to allow the furnace to cool. Record the temperature changes during sintering. After cooling to room temperature, turn off the heating. Grind and sieve the obtained particles in sequence to prepare dispersed calcium zirconate-coated zirconia particles.

[0060] 3) 7.5g of the obtained calcium zirconate-coated zirconium oxide particles were ball-milled with 5g of ordinary zirconium oxide powder (ball-to-material ratio of 1.5:1, rotation speed of 90r / min, ball-milling time of 240min) and then dry-pressed for preforming (80MPa, holding pressure for 2min). Subsequently, the dry-pressed preform was cold-isostatically pressed for preforming (250MPa, holding pressure for 60s) to obtain a green body. The green body was then microwave-sintered (1600℃, 4h) to prepare ZrO2-CaZrO3 composite ceramic.

[0061] Example 4

[0062] 1) Add 11g of zirconium oxide powder and 1g of calcium carbonate powder to a wide-mouthed bottle and ball mill them using a ball mill. The ratio of grinding balls, ethanol and powder is 1.5:1.2:1. The rotation speed is 150r / min and the mixing time is 200min. After ball milling, rotary evaporate at 60℃ for 20min. The powder obtained after rotary evaporation is passed through a 60-mesh sieve to obtain mixed powder.

[0063] 2) Place the mixed powder in a mortar and grind it evenly. Spread the evenly mixed powder evenly in a crucible, then place the crucible in a muffle furnace. After setting the heating and cooling regime, start heating. The heating and cooling regime is as follows: when the temperature is below 1000℃, maintain the heating rate at 9℃ / min. When the temperature rises to 1000℃, adjust the heating rate to maintain 4℃ / min. Raise the temperature to 1500℃ and hold for 220min. After the holding period, when the temperature is above 1000℃, maintain the cooling rate at 5℃ / min. When the temperature drops to 1000℃, adjust the heating rate to allow the furnace to cool. Record the temperature changes during sintering. After cooling to room temperature, turn off the heating. Grind and sieve the obtained particles in sequence to prepare dispersed calcium zirconate-coated zirconia particles.

[0064] 3) 6g of the obtained calcium zirconate-coated zirconium oxide particles were ball-milled with 5g of ordinary zirconium oxide powder (ball-to-material ratio of 1.5:1, rotation speed of 90r / min, ball-milling time of 240min) and then dry-pressed for preforming (80MPa, holding pressure for 3min). Subsequently, the dry-pressed preform was cold-isostatically pressed for preforming (230MPa, holding pressure for 90s) to obtain a green body. The green body was then microwave-sintered (1600℃, 200min) to prepare ZrO2-CaZrO3 composite ceramic.

[0065] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for producing a zirconia-calcium zirconate composite ceramic, characterized by, Includes the following steps: 1) Zirconia particles coated with calcium zirconate were obtained by calcining a mixture of zirconium oxide and calcium carbonate. 2) Zirconia particles coated with calcium zirconate were mixed with zirconium oxide, pressed into shape, and then sintered to obtain zirconium oxide-calcium zirconate composite ceramics; The mass ratio of zirconium oxide to calcium carbonate in step 1) is 100~110:10~12; The calcination temperature in step 1) is 1400~1600℃, and the calcination time is 180~240min; The calcination heating program described in step 1) is to heat the temperature to 1000℃ at a rate of 8~10℃ / min, and then heat it to the calcination temperature at a rate of 3~5℃ / min.

2. The method of claim 1, wherein the zirconia-calcium zirconate composite ceramic is prepared by the steps of: mixing a zirconia powder and a calcium zirconate powder to form a mixture; and sintering the mixture to form the zirconia-calcium zirconate composite ceramic. The mixing method described in step 1) is ball milling. The ball milling speed is 80~200 r / min, the ball milling time is 180~240 min, and the ball-to-material ratio is 1.5~2:

1.

3. The method of claim 1, wherein the zirconia-calcium zirconate composite ceramic is prepared by the steps of: mixing a zirconia powder and a calcium zirconate powder to form a mixture; and sintering the mixture to form the zirconia-calcium zirconate composite ceramic. In step 2), the mass ratio of the calcium zirconate-coated zirconium oxide particles to zirconium oxide is 0.5~1.5:

1.

4. The method for preparing a zirconium oxide-calcium zirconate composite ceramic according to claim 3, characterized in that, The pressing process described in step 2) includes sequential dry pressing pre-forming and cold isostatic pressing pre-forming; The pressure of the dry pressing preforming is 50~80MPa, and the holding time of the dry pressing preforming is 1~3min; The pressure of the cold isostatic pressing preforming is 150~300MPa, and the holding time of the cold isostatic pressing preforming is 60~90s.

5. The method of claim 4, wherein the zirconia-calcium zirconate composite ceramic is prepared by the steps of: mixing a zirconia powder and a calcium zirconate powder; and sintering the mixed powder. The sintering temperature in step 2) is 1400~1600℃, and the sintering time is 3~4h.

6. The zirconia-calcium zirconate composite ceramic prepared by the method according to any one of claims 1 to 5.

7. The application of the zirconia-calcium zirconate composite ceramic according to claim 6 in high-temperature alloy smelting.

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