Titanium black ceramic as well as preparation method and application thereof

Abstract

The invention discloses titanium black ceramic as well as a preparation method and application thereof. The preparation method comprises the following steps that a mixture of TiO and Ti is subjected to sinter molding or is firstly molded and then sintered, the titanium black ceramic TiOx is prepared, and x is larger than 0 and smaller than 1. The titanium black ceramic provided by the invention has low requirements on a preparation process and a simple preparation method, and the prepared titanium black ceramic has excellent mechanical properties.

Description

Technical Field

[0001] The present invention specifically relates to a titanium dioxide ceramic and a preparation method and application thereof. Background Art

[0002] As an important branch of the metal oxide ceramic system, titanium oxide ceramics have demonstrated irreplaceable advantages in many fields due to their unique physical and chemical properties, becoming an important supplement and upgrade direction for traditional oxide ceramics. Especially in the context of high-end fields such as aerospace and energy devices that place extremely high demands on the performance of structural materials, the development of new ceramic materials with both excellent mechanical strength and toughness is crucial to breaking through the bottleneck of their engineering applications. Traditional titanium dioxide (TiO2) ceramics have high mechanical brittleness (fracture toughness is only 2-3 MPa·m 1 / 2 ), low photocatalytic efficiency, insufficient high temperature stability and other defects make it difficult to meet the application requirements of extreme environments. Titanium oxide ceramics rely on the metal bond network formed by low-valent titanium (accounting for 30%) and oxygen vacancies (density 1.2×10 20 cm -3 ) synergistic mechanism, breaking through the performance bottleneck of traditional oxides, its fracture toughness (5.6MPa·m 1 / 2 ) and compressive strength (1.2GPa) are 100% and 40% higher than those of TiO2, respectively. It also possesses thermal shock resistance (performance retention ≥85% from -196°C to 1200°C) and radiation resistance (corrosion rate 0.001mm / year). However, the current titania preparation process still faces problems such as difficult-to-control reduction processes and insufficient grain boundary stability, which can affect the density and homogenization of titania ceramics, making them difficult to sinter or causing pores and cracks, affecting their hardness and toughness. Summary of the Invention

[0003] The present invention addresses the technical problem of overcoming the drawbacks of prior art titanium dioxide production processes, such as the stringent requirements for titanium dioxide preparation and the poor mechanical properties of titanium dioxide ceramics, by providing a titanium dioxide ceramic, its preparation method, and its application. The titanium dioxide ceramic provided by the present invention has low preparation process requirements and a simple preparation method, and the resulting titanium dioxide ceramic exhibits excellent mechanical properties.

[0004] The present invention solves the above technical problems through the following technical solutions:

[0005] The present invention provides a method for preparing titanium dioxide ceramics, which comprises the following steps: sintering a mixture of TiO and Ti into a shape or first forming and then sintering the mixture to obtain the titanium dioxide ceramics TiO x , where 0<x<1.

[0006] In the present invention, the TiO2 can be prepared by conventional preparation methods in the art or purchased commercially. The preparation method of the TiO2 preferably comprises the following steps: calcining and acid washing a mixture of TiO2 and Mg in sequence.

[0007] The particle size of the TiO2 can be 10-200 nm, preferably 10-100 nm, such as 20 nm, 40 nm, 60 nm, or 80 nm. The particle size of the Mg can be 50-500 mesh, such as 100-200 mesh. The molar ratio of the TiO2 to the Mg can be conventional in the art, generally 1:1.

[0008] The method for preparing the mixture of TiO2 and Mg preferably comprises the following steps: grinding TiO2 and Mg. The grinding is generally performed in a mortar. The grinding time can be 10-60 minutes, for example, 30 minutes or 40 minutes.

[0009] The calcination is generally performed in a tube furnace. The calcination atmosphere is generally an inert atmosphere, such as argon or nitrogen. The calcination temperature may be 700-1200°C, such as 900°C, 1000°C, or 1100°C. The calcination time may be 6-24 hours, such as 10 hours or 12 hours.

[0010] Among them, the type of acid used for the pickling can be conventional in the art, generally hydrochloric acid, sulfuric acid or nitric acid, for example, dilute hydrochloric acid obtained by mixing concentrated hydrochloric acid and deionized water in a volume ratio of 1:6. During the pickling process, the ratio of the mass of the solid powder to the volume of the acid can be 1: (3-10) g / mL, for example 1: 7 g / mL. The pickling is preferably carried out under stirring. The pickling time can be 20-60 min, for example 25 min, 30 min or 40 min. The number of pickling times can be conventional in the art, generally three times. After the pickling, washing, drying and grinding are generally required. Deionized water and / or ethanol can generally be used for the washing.

[0011] In the present invention, the molar ratio of TiO to Ti can be x:(1-x), wherein 0<x<1, for example, x is 0.02, 0.05, 0.08, 0.09, 0.1, 0.12, 0.15, 0.18, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.6, 0.72, 0.75, 0.8, 0.82 or 0.9, preferably 0.02<x≤0.08 or 0.12<x≤0.6, wherein x is the same as the sub-titanium oxide ceramic TiO x The x in .

[0012] In the present invention, the particle size of the Ti may be 50-500 mesh, for example, 100 mesh, 200 mesh, 325 mesh or 400 mesh.

[0013] In the present invention, the method for preparing the mixture of TiO and Ti preferably includes the following steps: uniformly grinding TiO powder and Ti powder. The grinding is generally performed in a mortar. The grinding time can be 10-30 minutes, for example, 20 minutes.

[0014] In the present invention, the sintering molding is preferably carried out by spark plasma sintering. The sintering molding is preferably carried out in a spark plasma furnace. The sintering molding is generally carried out in a vacuum or in an inert atmosphere. The rate of heating to the temperature of the sintering molding may be 40-110°C / min, for example, 50°C / min, 80°C / min or 100°C / min. The temperature of the sintering molding may be 1000-1800°C, for example, 1250°C, 1300°C or 1500°C. The time of the sintering molding may be 10-360min, for example, 15min, 20min, 30min, 50min, 100min, 180min or 250min.

[0015] When the spark plasma sintering method is adopted, the pressure during the sintering process may be 15-50 MPa, such as 20 MPa, 30 MPa, 35 MPa or 40 MPa.

[0016] In certain preferred embodiments, the sintering molding comprises the following steps: heating the mixture of TiO and Ti to 1300°C at a rate of 100°C / min, then continuing to heat the mixture to 1500°C at a rate of 50°C / min and keeping the temperature for 10-360 minutes.

[0017] In certain preferred embodiments, the sintering molding comprises the following steps: heating the mixture of TiO and Ti to 1300°C at a rate of 100°C / min under a pressure of 30 MPa, then continuing to heat the mixture to 1500°C at a rate of 50°C / min and keeping the temperature for 10-360 min.

[0018] In the present invention, when the method of forming first and then sintering is adopted: the forming method and the equipment used can be conventional in the field, such as tableting in a tablet press; the equipment used for sintering can be conventional in the field, such as in a tubular furnace or in a spark plasma furnace; the sintering is generally carried out in a vacuum or in an inert atmosphere; the rate of heating to the temperature of the sintering forming can be 40-110℃ / min, such as 50℃ / min, 80℃ / min or 100℃ / min; the sintering temperature can be 1000-1800℃, such as 1200℃, 1300℃, 1500℃ or 1550℃; the sintering time can be 10min-5h, such as 15min, 30min, 1h, 2h or 4.5h.

[0019] In the present invention, in order to further improve the density of the titania ceramic, preferably, the titania ceramic is further subjected to annealing treatment.

[0020] The annealing process is generally carried out in a vacuum furnace. During the annealing process, the oxygen partial pressure can be 10 -1 -10 -6 Pa, for example, 10 -5 The annealing treatment may be performed at a temperature of 800-1200° C., such as 900° C., 1000° C., or 1100° C. The annealing treatment may be performed for a time of 24-100 h, such as 48 h, 72 h, or 84 h.

[0021] In the present invention, the titanium oxide ceramic TiO x Here, x is, for example, 0.02, 0.05, 0.08, 0.09, 0.1, 0.12, 0.15, 0.18, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.6, 0.72, 0.75, 0.8, 0.82 or 0.9, preferably 0.02<x≤0.08 or 0.12<x≤0.6.

[0022] In the present invention, the shape of the titania ceramic can be conventional in the art, such as a sheet or a block.

[0023] The present invention also provides a titanium dioxide ceramic prepared by the above-mentioned preparation method.

[0024] In the present invention, the titania ceramic may have a Vickers hardness of 400-800 HV, for example, 450 HV, 500 HV, 559.04 HV, 600 HV, 650 HV, 671.09 HV, 700 HV, or 751.97 HV, preferably 450-800 HV. The titania ceramic may have an elastic modulus of 130-400 GPa, for example, 137.3 GPa, 150 GPa, 187.9 GPa, 200 GPa, 250 GPa, or 288.9 GPa. The titania ceramic may have a nanoindentation hardness of 7.5-14 GPa, for example, 8 GPa, 8.37 GPa, 9 GPa, 9.5 GPa, 10.21 GPa, 11 GPa, or 12.78 GPa.

[0025] The present invention also provides an application of the aforementioned titanium dioxide ceramic in aerospace materials, hydrogen storage containers, energy devices, extreme environment chemical engineering equipment or biomedical materials.

[0026] On the basis of conforming to the common sense in this field, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0027] The reagents and raw materials used in the present invention are commercially available.

[0028] The positive progress effect of the present invention is:

[0029] The titania ceramics provided by the present invention have low requirements on the preparation process and a simple preparation method, and the prepared titania ceramics have excellent mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the SEM image of the TiO powder prepared in Example 1;

[0031] Figure 2 This is the XRD pattern of the TiO powder prepared in Example 1;

[0032] Figure 3 TiO prepared in Example 2 0.05 SEM image of ceramic block;

[0033] Figure 4 TiO prepared in Example 7 0.05 SEM image of ceramic block. DETAILED DESCRIPTION

[0034] The present invention is further illustrated by way of examples below, but the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions, or selected according to the product specifications.

[0035] Example 1

[0036] Preparation of TiO powder: Nano-TiO2 (99.8%, 60 nm, Aladin) and Mg (≥99.0%, 100-200 mesh, Chinese medicine) were mixed in a quartz mortar at a molar ratio of 1:1 and ground for 30 minutes to achieve a uniform mixture. 10 g of the mixed powder was added to an alumina porcelain boat and placed in a tube furnace. Argon was passed through the furnace at a flow rate of 200 mL / min for 30 minutes to purge the atmosphere. The mixture was then heated to 1000°C at a rate of 5°C / min under this argon flow rate, maintained at this temperature for 10 hours, and then cooled to room temperature in the furnace. A flake sample was removed and ground into a powder in a quartz mortar. 30 mL of concentrated hydrochloric acid and 180 mL of deionized water were mixed and stirred to obtain dilute hydrochloric acid. In a beaker, 70 mL of dilute hydrochloric acid was added to the Mg-reduced TiO2 powder and stirred at 400 rpm for 30 minutes. After 5 minutes of filtration, an additional 70 mL of dilute hydrochloric acid was added to the residue. This process was repeated three times to remove the MgO. The filter residue was washed three times with deionized water and anhydrous ethanol, respectively, and then dried and ground to obtain TiO powder.

[0037] Example 2

[0038] TiO 0.05 Ceramic block sintering: TiO powder and Ti (99.5%, 325 mesh, Innochem) with a molar ratio of 0.05:0.95 were mixed in a quartz mortar and ground for 20 min to mix uniformly. TiO was prepared by spark plasma sintering (SPS) using a mini SPS spark plasma furnace (SPS-3T-5-MIN, Shanghai Chenhua Technology Co., Ltd.). 0.05 Ceramic block. A mass of 3.0 g of mixed powder was loaded into a graphite mold with an inner diameter of 12 mm. The powder sample was separated from the graphite mold and punch using 0.1 mm graphite paper. Under a uniaxial pressure of 30 MPa, the mixed ceramic was heated to 1300 ° C at a rate of 100 ° C / min in a vacuum (≤ 10 Pa), and then continued to heat to 1500 ° C at a rate of 50 ° C / min. The sample was kept at this temperature and pressure for 15 minutes and naturally cooled to room temperature to prepare TiO 0.05 Ceramic block. To minimize heat radiation, the mold was wrapped with graphite fleece. The surface graphite was removed using a grinder, and the block was sized to a cylindrical shape with a diameter of 11 mm and a thickness of 5 mm. One side of the bottom surface was polished using a polishing machine.

[0039] Example 3

[0040] TiO 0.15Ceramic block sintering: TiO powder and Ti (99.5%, 325 mesh, Innochem) with a molar ratio of 0.15:0.85 were mixed in a quartz mortar and ground for 20 min to mix uniformly. TiO was prepared by spark plasma sintering (SPS) using a mini SPS spark plasma furnace (SPS-3T-5-MIN, Shanghai Chenhua Technology Co., Ltd.). 0.15 Ceramic block. A mass of 3.0 g of mixed powder was loaded into a graphite mold with an inner diameter of 12 mm. The powder sample was separated from the graphite mold and punch using 0.1 mm graphite paper. Under a uniaxial pressure of 30 MPa, the mixed ceramic was heated to 1300 ° C at a rate of 100 ° C / min in a vacuum (≤ 10 Pa), and then continued to heat to 1500 ° C at a rate of 50 ° C / min. The sample was kept at this temperature and pressure for 30 minutes and naturally cooled to room temperature to prepare TiO 0.15 Ceramic block. To minimize heat radiation, the mold was wrapped with graphite fleece. The surface graphite was removed using a grinder, and the block was sized to a cylindrical shape with a diameter of 11 mm and a thickness of 5 mm. One side of the bottom surface was polished using a polishing machine.

[0041] Example 4

[0042] TiO 0.45 Ceramic block sintering: TiO powder and Ti (99.5%, 325 mesh, Innochem) with a molar ratio of 0.45:0.55 were mixed in a quartz mortar and ground for 20 min to mix uniformly. TiO was prepared by spark plasma sintering (SPS) using a mini SPS spark plasma furnace (SPS-3T-5-MIN, Shanghai Chenhua Technology Co., Ltd.). 0.45 Ceramic block. A mass of 3.0 g of mixed powder was loaded into a graphite mold with an inner diameter of 12 mm. The powder sample was separated from the graphite mold and punch using 0.1 mm graphite paper. Under a uniaxial pressure of 30 MPa, the mixed ceramic was heated to 1300 ° C at a rate of 100 ° C / min in a vacuum (≤ 10 Pa), and then continued to heat to 1500 ° C at a rate of 50 ° C / min. The sample was kept at this temperature and pressure for 180 minutes and naturally cooled to room temperature to prepare TiO 0.45 Ceramic block. To minimize heat radiation, the mold was wrapped with graphite fleece. The surface graphite was removed using a grinder, and the block was sized to a cylindrical shape with a diameter of 11 mm and a thickness of 5 mm. One side of the bottom surface was polished using a polishing machine.

[0043] Example 5

[0044] Compared with Example 2, except that the molar ratio of TiO powder to Ti was adjusted to 0.2:0.8, the other operations and conditions were the same as those in Example 2 to obtain TiO 0.2Ceramic block.

[0045] Example 6

[0046] Compared with Example 2, except that the molar ratio of TiO powder to Ti was adjusted to 0.35:0.65, the other operations and conditions were the same as those in Example 2 to obtain TiO 0.35 Ceramic block.

[0047] Example 7

[0048] The TiO prepared in Example 2 0.05 The ceramic block was annealed in a vacuum furnace at a heating rate of 5°C / min to 1000°C, kept at this temperature for 72 hours, and the oxygen partial pressure was controlled at 10 -5 Pa, and then cooled to room temperature in the furnace.

[0049] Comparative Example 1

[0050] Ti bulk metal sintering: Ti bulk metal was prepared by spark plasma sintering (SPS) in a mini SPS spark plasma furnace (SPS-3T-5-MIN, Shanghai Chenhua Technology Co., Ltd.). 3.0 g of Ti powder was loaded into a graphite mold with an inner diameter of 12 mm. The powder sample was separated from the graphite mold and punch using 0.1 mm graphite paper. Under a uniaxial pressure of 30 MPa, the mixed ceramic was heated in a vacuum (≤10 Pa) at a rate of 100°C / min to 1300°C and then at a rate of 50°C / min to 1500°C. The sample was maintained at this temperature and pressure for 15 minutes and then naturally cooled to room temperature to produce the Ti bulk metal. To minimize thermal radiation, the mold was wrapped with graphite fleece. The surface graphite was removed by grinding and the resulting cylindrical block was maintained at a diameter of 11 mm and a thickness of 5 mm. One side of the bottom surface was polished using a polishing machine.

[0051] Effect embodiment

[0052] (1) Morphology characterization and XRD testing

[0053] According to SEM ( Figure 1 ) and XRD( Figure 2 ) It can be seen that TiO powder was successfully prepared in Example 1. According to the crystal data in Table 1, the TiO powder prepared in Example 1 belongs to the monoclinic system and has a space group of A2 / m.

[0054] Table 1 Crystal data of TiO powder prepared in Example 1

[0055]

[0056]

[0057] according to Figure 3 and Figure 4 The SPS sintered samples exhibit dense, parallel, linear scratches approximately 1-3 μm wide, left by the grinding treatment prior to mechanical testing. Some of these scratches are accompanied by micro-fractures due to grain flaking, and the surface grains are disoriented and harbor microcracks. However, after vacuum annealing, the scratches on the samples are significantly reduced, with only very shallow traces remaining. The overall surface is smooth and dense, with improved grain boundary definition and an increase in size from approximately 2-5 μm to 3-6 μm. This suggests that atomic diffusion during the annealing process fills the scratch pits and repairs lattice distortion. Annealing promotes thermally activated atomic diffusion, repairing the submicron surface defect network caused by grinding and reducing stress concentration. It also promotes dislocation rearrangement, eliminating grinding-induced residual stress (from ~200 MPa to ~50 MPa) and optimizing the grain boundary structure (reducing grain boundary energy by approximately 30%), providing a structurally stable sample for mechanical testing.

[0058] (2) Vickers hardness test

[0059] The Vickers hardness was tested on the polished surface of the sample using a Vickers hardness tester (HMV-G21D) with a test load of HV0.5 (4.903 N) and a holding time of 15 s. Each sample was tested four times and the average value was taken.

[0060] Vickers hardness test results are shown in Table 2:

[0061] Table 2 Vickers hardness test results

[0062]

[0063] (3) Nanoindentation hardness and elastic modulus test

[0064] Using an in-situ nanomechanical tester (G200), the Poisson's ratio of the sample was set to 0.3, and the nanoindentation hardness and elastic modulus were tested on the polished surface of the sample in a continuous depth range of 600-900 nm in the thickness direction of the sample. Each sample was tested five times and the average value was taken.

[0065] Table 3 Nanoindentation hardness and elastic modulus test results

[0066]

[0067] (4) Young's modulus test

[0068] The Young's modulus of the material was tested using a universal testing machine. The test results are shown in Table 4.

[0069] Table 4

[0070]

[0071] According to Table 4, the oxygen content has a nonlinear effect on the mechanical properties of titanium-based materials, which is "strengthening first and then weakening": low oxygen (0.05) significantly increases the Young's modulus to 332.57 GPa through solid solution strengthening; medium oxygen (0.2) causes the modulus to drop back to 254.12 GPa due to solid solution saturation or second phase initiation; high oxygen (0.35) causes the modulus to be close to pure titanium (119.17 GPa) due to the dominance of the brittle phase.

[0072] Although specific embodiments of the present invention have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, and such changes and modifications are intended to fall within the scope of the present invention.

Claims

1. A method for preparing titanium dioxide ceramics, characterized in that: The method comprises the following steps: sintering a mixture of TiO and Ti to form a product or forming the product first and then sintering the product to obtain the titanium dioxide ceramic TiO x , where 0<x<1.

2. The method for preparing titanium dioxide ceramics according to claim 1, wherein: The molar ratio of TiO to Ti is x:(1-x), wherein 0<x<1, for example, x is 0.02, 0.05, 0.08, 0.09, 0.1, 0.12, 0.15, 0.18, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.6, 0.72, 0.75, 0.8, 0.82 or 0.9, preferably 0.02<x≤0.08 or 0.12<x≤0.6; And / or, the particle size of Ti is 50-500 mesh, such as 100 mesh, 200 mesh, 325 mesh or 400 mesh.

3. The method for preparing titanium dioxide ceramics according to claim 1 or 2, wherein: The sintering molding satisfies one or more of the following conditions: (1) The sintering molding adopts spark plasma sintering method; When the spark plasma sintering method is used, the pressure during the sintering process is preferably 15-50 MPa, such as 20 MPa, 30 MPa, 35 MPa or 40 MPa; (2) The sintering temperature is 1000-1800°C, for example, 1250°C, 1300°C or 1500°C; (3) The sintering time is 10-360 min, for example, 15 min, 20 min, 30 min, 50 min, 100 min, 180 min or 250 min.

4. The method for preparing titanium dioxide ceramics according to claim 1 or 2, wherein: The sintering molding comprises the following steps: heating the mixture of TiO and Ti to 1300° C. at a rate of 100° C. / min, then continuing to heat to 1500° C. at a rate of 50° C. / min and keeping the temperature for 10-360 minutes; The sintering molding preferably includes the following steps: under a pressure of 30 MPa, heating the mixture of TiO and Ti to 1300° C. at a rate of 100° C. / min, then continuing to heat to 1500° C. at a rate of 50° C. / min and keeping the temperature for 10-360 minutes.

5. The method for preparing titanium dioxide ceramics according to claim 1 or 2, wherein: When the method of forming first and then sintering is adopted, the sintering temperature is 1000-1800°C, for example, 1200°C, 1300°C, 1500°C or 1550°C; And / or, the sintering time is 10 min-5 h, for example, 15 min, 30 min, 1 h, 2 h or 4.5 h.

6. The method for preparing titania ceramics according to claim 1 or 2, wherein: annealing the titania ceramic according to claim 1; The annealing treatment temperature is preferably 800-1200°C, such as 900°C, 1000°C or 1100°C; the annealing treatment time is preferably 24-100h, such as 48h, 72h or 84h.

7. The method for preparing titania ceramics according to claim 1 or 2, wherein: The titanium dioxide ceramic TiO x wherein x is 0.02, 0.05, 0.08, 0.09, 0.1, 0.12, 0.15, 0.18, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.6, 0.72, 0.75, 0.8, 0.82 or 0.9, preferably 0.02 < x ≤ 0.08 or 0.12 < x ≤ 0.

6.

8. The method for preparing titanium dioxide ceramics according to claim 1 or 2, wherein: The preparation method of TiO preferably comprises the following steps: calcining and acid washing a mixture of TiO2 and Mg in sequence; The calcination temperature is preferably 700-1200° C., such as 900° C., 1000° C. or 1100° C.; the calcination time is preferably 6-24 h, such as 10 h or 12 h.

9. A titania ceramic produced by the method for producing a titania ceramic according to any one of claims 1 to 8.

10. Use of the titania ceramic according to claim 9 in aerospace materials, hydrogen storage containers, energy devices, extreme environment chemical engineering equipment or biomedical materials.

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