Zirconia ceramic and method for producing the same

Abstract

The application provides a zirconia ceramic and a preparation method thereof, and belongs to the technical field of ceramics. First, zirconia, diyttrium trioxide, di-niobium pentoxide, erbium oxide, a dispersing agent and water are mixed to obtain a mixed slurry; then the mixed slurry is sequentially subjected to sand milling, spray granulation and dry pressing forming to obtain a ceramic green body; finally, the ceramic green body is sequentially subjected to glue removal and sintering to obtain the zirconia ceramic. The zirconia ceramic prepared by the application has a photochromic effect, can reversibly change color through alternating 365nm ultraviolet light irradiation and heating treatment, and the color development-decoloration process has high reversibility and cycle life.

Description

Technical Field

[0001] This invention relates to the field of ceramic technology, and in particular to a zirconia ceramic and its preparation method. Background Technology

[0002] ZrO2 ceramics possess characteristics such as low thermal conductivity, low coefficient of thermal expansion, high chemical stability, excellent mechanical properties, and good corrosion resistance. These features have made them a research hotspot in scientific research and they are widely used in various industrial and daily life fields, including zirconium oxide grinding media, ceramic cutting tools, dental materials, refractory materials, oxygen sensors, instruments, and high-end decorative ceramic components. In recent years, with the improvement of people's living standards, the requirements for colored zirconium oxide high-end decorative ceramic products have also been continuously increasing, such as in terms of color, gloss, and brightness.

[0003] Photochromism refers to the reversible conversion of a substance between two distinctly different color states, induced by light irradiation in at least one direction. Due to changes in its internal structure, a significant alteration in the absorption peaks before and after irradiation can be observed in the ultraviolet diffuse reflectance spectrum, which is the direct cause of its macroscopic color change phenomenon. Currently, the research focus of photochromic materials is to utilize the photochromic properties of materials to achieve reversible modulation of fluorescence emission intensity, thereby designing materials with high fluorescence modulation contrast to meet their applications in anti-counterfeiting and optical information storage. However, research combining photochromic functionality with the structural properties of zirconia ceramics has not yet been reported. Therefore, while ensuring the excellent structural properties of zirconia ceramics, it is urgent to study a zirconia ceramic and its preparation method to solve the problem of its ability to display only a single color. Summary of the Invention

[0004] The purpose of this invention is to provide a zirconia ceramic and its preparation method, so as to solve the problem that zirconia ceramics in the prior art can only achieve single-color display.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing zirconia ceramics, comprising the following steps:

[0007] (1) Zirconia, yttrium oxide, niobium pentoxide, erbium oxide, dispersant and water are mixed to obtain a mixed slurry;

[0008] (2) The mixed slurry is sequentially subjected to sand milling, spray granulation, and dry pressing to obtain a ceramic body;

[0009] (3) The ceramic blanks are sequentially debonded and sintered to obtain zirconium oxide ceramics.

[0010] Preferably, in step (1), the mass ratio of zirconium oxide, yttrium oxide, niobium pentoxide and erbium oxide is 567-756:33-44:199.3-398.6:0.7-1.4.

[0011] Preferably, in step (1), the dispersant comprises one or more of polyammonium methacrylate, ammonium polyacrylate, sodium tripolyphosphate, polyethylene glycol 2000, and sodium hexametaphosphate.

[0012] Preferably, the dispersant accounts for 0.25 to 0.45% of the total mass of zirconium oxide, yttrium oxide, niobium pentoxide, and erbium oxide.

[0013] Preferably, in step (1), the solid content of the mixed slurry is 45-55 wt%.

[0014] Preferably, in step (2), the grinding speed is 1500-2000 rpm and the grinding time is 2-6 hours.

[0015] Preferably, in step (2), polyvinyl alcohol is added after the mixed slurry is sand-milled and then spray-granulated.

[0016] The polyvinyl alcohol comprises 0.3% to 1.5% of the total mass of zirconium oxide, yttrium oxide, niobium pentoxide, and erbium oxide.

[0017] Preferably, in step (2), the atomization frequency of spray granulation is 36-46 Hz, the inlet air temperature of spray granulation is 200-250°C, and the outlet air temperature of spray granulation is 85-95°C.

[0018] Preferably, in step (3), the temperature for removing the adhesive is 500-700℃ and the time for removing the adhesive is 6-10h; the temperature for sintering is 1250-1450℃ and the time for sintering is 2-6h.

[0019] The present invention provides a zirconia ceramic prepared by the above preparation method, wherein the zirconia ceramic has a photochromic effect.

[0020] The beneficial effects of this invention are:

[0021] (1) The present invention refines the powder in the mixed slurry to the nanoscale (below 80nm) through the sand milling process, which enhances the activity of the powder, shortens the mass transfer distance between particles, and enables the colorant erbium oxide to be mixed evenly, thus making up for the defects of the traditional solid-phase reaction method, which easily causes uneven color distribution of ceramics, high sintering temperature, and low production efficiency.

[0022] (2) Only a suitable amount of deionized water needs to be added before sand milling. The preparation process is simple and convenient, with low cost, short cycle, and good repeatability. It is more suitable for industrial production and solves the problems of high cost and environmental pollution caused by the large amount of deionized water required for washing chloride ions in the co-precipitation process.

[0023] (3) The zirconia ceramic prepared by the present invention has a photochromic effect. It can undergo reversible color change by alternating ultraviolet light irradiation and heat treatment. It also has high photochromic contrast, fast response time, high reversibility and cycle life in the color development-decolorization process, and excellent mechanical properties.

[0024] (4) By adjusting the amount of niobium pentoxide added, the present invention can prepare a series of zirconia ceramics with dense structure and different photochromic contrast. Attached Figure Description

[0025] Figure 1 This is a field emission scanning electron microscope image of the zirconia ceramic prepared in Example 3;

[0026] Figure 2 The image shows the XRD pattern of the zirconia ceramic prepared in Example 3.

[0027] Figure 3 The ultraviolet reflectance spectrum of the zirconia ceramic prepared in Example 3 is shown below.

[0028] Figure 4 The graph shows the reflectance change at 480 nm of the zirconia ceramic prepared in Example 3 after six cycles of alternating 365 nm ultraviolet irradiation and heat treatment.

[0029] Figure 5 Comparison images of zirconia ceramics prepared in Examples 1, 2, 3, 4 and 5 before and after irradiation with 365nm light. Detailed Implementation

[0030] This invention provides a method for preparing zirconia ceramics, comprising the following steps:

[0031] (1) Zirconia, yttrium oxide, niobium pentoxide, erbium oxide, dispersant and water are mixed to obtain a mixed slurry;

[0032] (2) The mixed slurry is sequentially subjected to sand milling, spray granulation, and dry pressing to obtain a ceramic body;

[0033] (3) The ceramic blanks are sequentially debonded and sintered to obtain zirconium oxide ceramics.

[0034] In this invention, in step (1), the mass ratio of zirconium oxide, yttrium oxide, niobium pentoxide and erbium oxide is 567-756:33-44:199.3-398.6:0.7-1.4, preferably 614-709:36-41:249.1-348.1:0.9-1.3, and more preferably 661:39:298.9:1.1.

[0035] In this invention, in step (1), the dispersant comprises one or more of polyammonium methacrylate, ammonium polyacrylate, sodium tripolyphosphate, polyethylene glycol 2000 and sodium hexametaphosphate, preferably one or more of ammonium polyacrylate, sodium tripolyphosphate and polyethylene glycol 2000, and more preferably sodium tripolyphosphate and / or polyethylene glycol 2000.

[0036] In this invention, the mass of the dispersant accounts for 0.25 to 0.45% of the total mass of zirconium oxide, yttrium oxide, niobium pentoxide and erbium oxide, preferably 0.28 to 0.40%, and more preferably 0.3 to 0.35%.

[0037] In this invention, in step (1), the solid content of the mixed slurry is 45-55 wt%, preferably 48-52 wt%, and more preferably 50 wt%.

[0038] In this invention, in step (2), the grinding speed is 1500-2000 rpm, preferably 1600-1900 rpm, more preferably 1700-1800 rpm, and the grinding time is 2-6 hours, preferably 3-5 hours, more preferably 4 hours.

[0039] In this invention, the preferred grinding media used during sanding is zirconia beads, with a particle size of 0.1–0.8 mm, preferably 0.2–0.6 mm, and more preferably 0.3–0.6 mm.

[0040] In this invention, the ball-to-material ratio in the sand mill is 1:1 to 5, preferably 1:2 to 4, and more preferably 1:3.

[0041] In this invention, the particle size of the powder in the mixed slurry after sand milling is <80nm, preferably 30-70nm, and more preferably 40-60nm.

[0042] In this invention, in step (2), the mixed slurry is sand-milled, then polyvinyl alcohol is added and spray-granulated.

[0043] The polyvinyl alcohol comprises 0.3-1.5% of the total mass of zirconium oxide, yttrium oxide, niobium pentoxide, and erbium oxide, preferably 0.6-1.2%, and more preferably 0.9-1.1%.

[0044] In this invention, in step (2), the atomization frequency of spray granulation is 36-46 Hz, preferably 38-43 Hz, and more preferably 40 Hz; the inlet air temperature of spray granulation is 200-250 ℃, preferably 210-240 ℃, and more preferably 220-230 ℃; and the outlet air temperature of spray granulation is 85-95 ℃, preferably 90 ℃.

[0045] In this invention, in step (2), the pressure of dry pressing is 6 to 10 MPa, preferably 7 to 9 MPa, and more preferably 8 MPa.

[0046] In this invention, in step (3), the temperature for removing the adhesive is 500-700℃, preferably 550-650℃, and more preferably 600℃; the time for removing the adhesive is 6-10h, preferably 7-9h, and more preferably 8h; the temperature for sintering is 1250-1450℃, preferably 1300-1400℃, and more preferably 1350℃; the time for sintering is 2-6h, preferably 3-5h, and more preferably 4h.

[0047] In this invention, the sintering is preferably carried out in an air atmosphere.

[0048] The present invention provides a zirconia ceramic prepared by the above preparation method, wherein the zirconia ceramic has a photochromic effect.

[0049] 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.

[0050] Example 1

[0051] 567 parts by weight of zirconium oxide, 33 parts by weight of yttrium oxide, 398.6 parts by weight of niobium pentoxide, 1.4 parts by weight of erbium oxide, and 2.5 parts by weight of polymethyl methacrylate were added to deionized water and mixed to obtain a mixed slurry with a solid content of 50 wt%.

[0052] The mixed slurry was placed in a sand mill and milled for 2 hours at 1500 rpm using 0.7 mm zirconia beads (with a ball-to-particle ratio of 1:1). Polyvinyl alcohol (0.3% of the total mass of zirconia, yttrium oxide, niobium pentoxide, and erbium oxide) was added to the milled slurry (the particle size of the powder in the slurry was 60 nm). Then, the atomization frequency of the spray drying equipment was adjusted to 46 Hz, the inlet air temperature to 250 ℃, and the outlet air temperature to 95 ℃ for spray granulation. The resulting ceramic powder was then dry-pressed into ceramic green bodies under a pressure of 10 MPa.

[0053] The ceramic blank was placed in a muffle furnace for debinding at a temperature of 500℃ for 10 hours; finally, it was placed in a muffle furnace and sintered in air at a temperature of 1250℃ for 6 hours to obtain zirconia ceramic.

[0054] Example 2

[0055] 614 parts by weight of zirconium oxide, 36 parts by weight of yttrium oxide, 348.7 parts by weight of niobium pentoxide, 1.3 parts by weight of erbium oxide, and 3 parts by weight of ammonium polyacrylate were added to deionized water and mixed to obtain a mixed slurry with a solid content of 50 wt%.

[0056] The mixed slurry was placed in a sand mill and milled for 3 hours at 1600 rpm using 0.5 mm zirconia beads (with a ball-to-particle ratio of 1:2). Polyvinyl alcohol (0.6% of the total mass of zirconia, yttrium oxide, niobium pentoxide, and erbium oxide) was added to the milled slurry (the particle size of the powder in the slurry was 70 nm). Then, the atomization frequency of the spray drying equipment was adjusted to 38 Hz, the inlet air temperature to 240 ℃, and the outlet air temperature to 95 ℃ for spray granulation. The resulting ceramic powder was then dry-pressed into ceramic green bodies under a pressure of 9 MPa.

[0057] The ceramic blank was placed in a muffle furnace for debinding at a temperature of 550°C for 9 hours. Finally, it was placed in a muffle furnace and sintered in air at 1300°C for 5 hours to obtain zirconia ceramic.

[0058] Example 3

[0059] 661 parts by weight of zirconium oxide, 39 parts by weight of yttrium oxide, 298.9 parts by weight of niobium pentoxide, 1.1 parts by weight of erbium oxide, and 3.5 parts by weight of sodium tripolyphosphate were added to deionized water and mixed to obtain a mixed slurry with a solid content of 50 wt%.

[0060] The mixed slurry was placed in a sand mill and milled for 4 hours at 1700 rpm using 0.4 mm zirconia beads (with a ball-to-particle ratio of 1:3). Polyvinyl alcohol (0.9% of the total mass of zirconia, yttrium oxide, niobium pentoxide, and erbium oxide) was added to the milled slurry (the particle size of the powder in the slurry was 50 nm). Then, the atomization frequency of the spray drying equipment was adjusted to 40 Hz, the inlet air temperature to 230 ℃, and the outlet air temperature to 90 ℃ for spray granulation. The resulting ceramic powder was then dry-pressed into ceramic green bodies under a pressure of 8 MPa.

[0061] The ceramic blank was placed in a muffle furnace for debinding at a temperature of 600℃ for 8 hours. Finally, it was placed in a muffle furnace and sintered in air at a temperature of 1350℃ for 4 hours to obtain zirconia ceramic.

[0062] Figure 1 This is a field emission scanning electron microscope image of the zirconia ceramic prepared in Example 3. Figure 1 It can be seen that zirconia ceramics have no obvious pores and have a good dense microstructure, mainly consisting of lamellar grains.

[0063] Figure 2 The image shows the XRD pattern of the zirconia ceramic prepared in Example 3. Figure 2 It can be seen that the zirconia ceramic has good crystallinity, and the crystal phases are tetragonal ZrO2 and Zr6Nb2O. 17 The composite phase.

[0064] Figure 3 The image shows the ultraviolet reflectance spectrum of the zirconia ceramic prepared in Example 3. Figure 3 It can be seen that after irradiation with 365nm ultraviolet light for 1 minute, the reflectivity of zirconia ceramics drops sharply and the surface color changes significantly.

[0065] Figure 4 This is a graph showing the reflectance change at 480 nm of the zirconia ceramic prepared in Example 3 after six cycles of alternating 365 nm ultraviolet irradiation and heat treatment. Figure 4 It can be seen that when zirconia ceramics are subjected to alternating cycles of 365nm light irradiation and heat treatment for 6 times, the emissivity remains basically unchanged in both the colored and decolored states, demonstrating good reversibility and cycle life.

[0066] Example 4

[0067] 709 parts by weight of zirconium oxide, 41 parts by weight of yttrium oxide, 249.1 parts by weight of niobium pentoxide, 0.9 parts by weight of erbium oxide, and 4 parts by weight of polyethylene glycol 2000 were added to deionized water and mixed to obtain a mixed slurry with a solid content of 50 wt%.

[0068] The mixed slurry was placed in a sand mill and milled for 5 hours at 1800 rpm using 0.3 mm zirconia beads (with a ball-to-particle ratio of 1:4). Polyvinyl alcohol (1.2% of the total mass of zirconia, yttrium oxide, niobium pentoxide, and erbium oxide) was added to the milled slurry (the particle size of the powder in the slurry was 40 nm). Then, the atomization frequency of the spray drying equipment was adjusted to 43 Hz, the inlet air temperature to 215 ℃, and the outlet air temperature to 90 ℃ for spray granulation. The resulting ceramic powder was then dry-pressed into ceramic green bodies under a pressure of 7 MPa.

[0069] The ceramic blank was placed in a muffle furnace for debinding at a temperature of 650°C for 7 hours. Finally, it was placed in a muffle furnace and sintered in air at 1400°C for 3 hours to obtain zirconia ceramic.

[0070] Example 5

[0071] 756 parts by weight of zirconium oxide, 44 parts by weight of yttrium oxide, 199.3 parts by weight of niobium pentoxide, 0.7 parts by weight of erbium oxide, and 4.5 parts by weight of sodium hexametaphosphate were added to deionized water and mixed to obtain a mixed slurry with a solid content of 50 wt%.

[0072] The mixed slurry was placed in a sand mill and milled for 6 hours at 2000 rpm using 0.2 mm zirconia beads (with a ball-to-particle ratio of 1:5). Polyvinyl alcohol (1.5% of the total mass of zirconia, yttrium oxide, niobium pentoxide, and erbium oxide) was added to the milled slurry (the particle size of the powder in the slurry was 30 nm). Then, the atomization frequency of the spray drying equipment was adjusted to 46 Hz, the inlet air temperature to 200 ℃, and the outlet air temperature to 85 ℃ for spray granulation. The resulting ceramic powder was then dry-pressed into ceramic green bodies under a pressure of 6 MPa.

[0073] The ceramic blank was placed in a muffle furnace for debinding at a temperature of 700℃ for 6 hours; finally, it was placed in a muffle furnace and sintered in air at a temperature of 1450℃ for 2 hours to obtain zirconia ceramic.

[0074] Comparative Example 1

[0075] The difference from Example 1 is that erbium oxide was not added, while all other conditions were the same.

[0076] Performance testing:

[0077] (1) Hardness test: Vickers hardness was determined by indentation method. The Vickers hardness value of zirconia ceramics was tested using an automatic Vickers hardness tester. The indentation load was 0.1 kgf and the holding time was 10 s. Before the test, the surface of zirconia ceramics was polished to ensure that there were no obvious scratches under the microscope. Five indentation tests were performed on each sample, and the average value of the five measurements was taken as the final Vickers hardness value.

[0078] (2) Toughness test: Fracture toughness was tested using an automatic Vickers hardness tester. Indentations and cracks were generated on the polished zirconia ceramic surface. The indentation load was 0.3 kgf and the holding time was 15 s. The fracture toughness value was calculated by measuring the crack length and the diagonal length of the indentation. Five indentation tests were performed on each sample, and the average value of the five measurements was taken as the final fracture toughness value.

[0079] The results of the hardness and toughness tests are shown in Table 1.

[0080] Table 1 shows the performance test results of the zirconia ceramics prepared in Examples 1-5 and Comparative Example 1.

[0081]

[0082]

[0083] As can be seen from Table 1, the zirconia ceramics prepared by this invention have good mechanical properties, and the doping of the colorant erbium oxide did not reduce the mechanical properties of the zirconia ceramics.

[0084] Figure 5 These are comparative images of zirconia ceramics prepared in Examples 1, 2, 3, 4, and 5 before and after irradiation with 365 nm light. Figure 5 It can be seen that the zirconium oxide ceramics prepared with different amounts of niobium pentoxide have different photochromic contrasts.

[0085] As can be seen from the above embodiments, the present invention provides a zirconia ceramic and its preparation method. The present invention first mixes zirconia, yttrium trioxide, niobium pentoxide, erbium oxide, a dispersant, and water to obtain a mixed slurry; then, the mixed slurry is sequentially subjected to sand milling, spray granulation, and dry pressing to obtain a ceramic green body; finally, the ceramic green body is sequentially subjected to debinding and sintering to obtain zirconia ceramic. The zirconia ceramic prepared by the present invention exhibits a photochromic effect; through alternating irradiation with ultraviolet light and heat treatment, a reversible color change can occur, and this color development-decolorization process has high reversibility and cycle life.

[0086] 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 preparing zirconia ceramic, characterized in that, Includes the following steps: (1) Zirconia, yttrium oxide, niobium pentoxide, erbium oxide, dispersant and water are mixed to obtain a mixed slurry; (2) The mixed slurry is sequentially subjected to sand milling, spray granulation, and dry pressing to obtain a ceramic body; (3) The ceramic blank is sequentially debonded and sintered to obtain zirconium oxide ceramic; In step (1), the mass ratio of zirconium oxide, yttrium oxide, niobium pentoxide and erbium oxide is 567-756:33-44:199.3-398.6:0.7-1.

4.

2. The preparation method according to claim 1, characterized in that, In step (1), the dispersant comprises one or more of the following: ammonium polymethacrylate, ammonium polyacrylate, sodium tripolyphosphate, polyethylene glycol 2000, and sodium hexametaphosphate.

3. The preparation method according to claim 1 or 2, characterized in that, The dispersant accounts for 0.25 to 0.45% of the total mass of zirconium oxide, yttrium oxide, niobium pentoxide, and erbium oxide.

4. The preparation method according to claim 3, characterized in that, In step (1), the solid content of the mixed slurry is 45-55 wt%.

5. The preparation method according to claim 4, characterized in that, In step (2), the grinding speed is 1500-2000 rpm and the grinding time is 2-6 hours.

6. The preparation method according to claim 2 or 4, characterized in that, In step (2), after the mixed slurry is sand-milled, polyvinyl alcohol is added and then spray-granulated; the mass of the polyvinyl alcohol accounts for 0.3 to 1.5% of the total mass of zirconium oxide, yttrium oxide, niobium pentoxide and erbium oxide.

7. The preparation method according to claim 6, characterized in that, In step (2), the atomization frequency of spray granulation is 36-46 Hz, the inlet air temperature of spray granulation is 200-250℃, and the outlet air temperature of spray granulation is 85-95℃.

8. The preparation method according to claim 5 or 7, characterized in that, In step (3), the temperature for removing the adhesive is 500-700℃ and the time for removing the adhesive is 6-10h; the temperature for sintering is 1250-1450℃ and the time for sintering is 2-6h.

9. The zirconia ceramic prepared by the method according to any one of claims 1 to 8, characterized in that, The zirconia ceramic exhibits a photochromic effect.

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