Method for preparing yellow zirconium oxide powder through pigment and zirconium oxide co-grinding method and application of yellow zirconium oxide powder

Abstract

The invention discloses a method for preparing yellow zirconium oxide powder through a pigment and zirconium oxide co-grinding method and application of the yellow zirconium oxide powder, and relates to the technical field of functional ceramic materials.The method comprises the following steps that a yellow pigment precursor is prepared; mixing the zirconium oxide powder and the yellow pigment precursor, and carrying out co-grinding treatment; drying, granulating and screening the slurry subjected to co-grinding treatment to obtain yellow zirconium oxide powder; performing heat treatment on the yellow zirconium oxide powder to obtain the yellow zirconium oxide powder with excellent binding force and heat-resistant stability; the pigment is adopted as the prefabricated hydroxide to be co-ground and introduced in the sanding stage, uniform dispersion is easier to achieve, pigment aggregation and color spots are reduced, pigment components can be more stably combined with a zirconium oxide matrix after annealing and solution treatment, and the risks of high-temperature volatilization, precipitation and decoloration are reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional ceramic materials, and particularly relates to a method for preparing yellow zirconia powder by co-milling of pigments and zirconia and application thereof. BACKGROUND

[0002] Zirconia (ZrO2) is widely used in structural ceramics, thermal barrier coatings, functional ceramics and other fields due to its high strength, wear resistance, thermal shock resistance and other excellent properties. However, traditional zirconia is usually milky white or ivory white, and does not have color properties. In order to meet the needs of decoration, identification, functionalization and other needs, researchers add pigments or doped metal ions to zirconia to prepare colored zirconia materials.

[0003] However, during high-temperature sintering, many pigment components (especially colored metal oxides or rare earth oxides) will volatilize, phase separate, migrate or precipitate at high temperatures, resulting in color fading, aggregation or destruction of the matrix structure. In addition, uneven distribution of pigments, poor interface bonding, poor compatibility of pigments and matrix, color spots and other problems also seriously affect the actual application performance. Therefore, a new preparation method is urgently needed to uniformly and stably fix the pigments in the zirconia powder, while taking into account the densification, mechanical properties and thermal stability of the zirconia matrix. SUMMARY

[0004] The present application aims to provide a method for preparing yellow zirconia powder by co-milling of pigments and zirconia and application thereof, to solve the problems existing in the prior art as described in the background.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions: A method for preparing yellow zirconia powder by co-milling of pigments and zirconia, comprising the following steps: S1: preparing a yellow pigment precursor; S2: mixing zirconia powder and the yellow pigment precursor for co-milling treatment; S3: drying, granulating and sieving the slurry after co-milling treatment to obtain yellow zirconia powder; S4: heat treating the yellow zirconia powder to obtain yellow zirconia powder with excellent bonding force and heat resistance.

[0006] Preferably, in S1, one or more water-soluble metal salts corresponding to color-developing metal elements are selected as precursors; the pH value is controlled to be 7-10 in the aqueous solution, so that the metal ions are precipitated as metal hydroxides or co-precipitated gels, which are washed, dried at a temperature of 110℃-125℃, and heat treated at 500℃-1200℃ for 0.5h-2h to convert the hydroxides into oxide or oxide state stable pigment powder.

[0007] Preferably, in S2, the commercial zirconia powder is dispersed in water or a suitable solvent, and the pigment precursor is gradually added to the mixed slurry in the co-milling stage, so that the pigment particles are uniformly dispersed around the zirconia particles and the crystal boundaries by adjusting the milling time, milling medium, ball-to-material ratio, rotation speed, pH value and dispersant, so that the pigment particles are not easily aggregated.

[0008] Preferably, in S3, the slurry after co-milling is subjected to spray drying, drum drying or air drying treatment, and if there is agglomeration or bulk after drying, dry grinding, ball milling or grinding to the required particle size is performed, and screening is performed to remove large particle sizes or agglomerates, so as to ensure that the final powder particle size distribution meets the design requirements.

[0009] Preferably, in S4, the powder is annealed in an oxidizing atmosphere or an inert atmosphere, and the temperature is set to 500-1200 ℃.

[0010] Preferably, in S2, the milling time is set to 2-10h, the milling medium is selected to be alumina or zirconia balls, the ball-to-material ratio is 6:1-10:1, the rotation speed is set to 200-600rpm, the pH value is set to 8-11, and the dispersant is selected to be polyvinyl alcohol, polyethylene glycol or polyacrylammonium.

[0011] Preferably, in S2, the pigment doping adopts a multi-doping or synergistic doping method, and an interfacial modifier is added in the co-milling stage or the post-treatment stage to enhance the interface bonding between the pigment and the zirconia.

[0012] The application also provides an application of the yellow zirconia powder prepared by the above method, and the yellow zirconia powder is applied to the preparation of ceramic materials.

[0013] Preferably, the application of the yellow zirconia powder comprises the following steps: The yellow zirconia powder is prepared into a green body or a structural part by using an existing ceramic forming method, sintering is performed at a temperature of 1350-1600 °C, and finally a yellow zirconia ceramic material or device with uniform yellow color, dense structure and stable performance is obtained.

[0014] Compared with the prior art, the application has the following beneficial effects: 1. In the application, the pigment is used as a pre-prepared hydroxide and is introduced in the sand milling stage, so that uniform dispersion is more easily achieved, pigment aggregation and color spots are reduced, and after annealing and solid solution treatment, the pigment components can be more stably combined with the zirconia matrix, reducing the risk of high-temperature volatilization, precipitation and discoloration.

[0015] 2、The method of the present application has little damage to the microstructure of the zirconia substrate, so that the zirconia substrate still has good densification ability and mechanical properties, and the sintered ceramic has stable, uniform color and good adhesion, which is suitable for color structural ceramic, decorative ceramic, electronic ceramic and other application scenarios, and the process is relatively simple and easy to industrialize. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 A yellow zirconia ceramic prepared by the present application. DETAILED DESCRIPTION

[0017] In order to make the technical means, creative features, purposes and effects of the present application easy to understand, the present application will be further described below in combination with specific embodiments.

[0018] Please refer to Figure 1 The present application provides the following technical solutions: A method for preparing yellow zirconia powder by co-milling of pigment and zirconia, comprising the following steps: S1: preparing a yellow pigment precursor; Select one or more water-soluble metal salts (preferably nitrate, carbonate, chloride or complex metal salt) corresponding to the color-producing metal elements (such as Fe, V, Cr, Mn, Ce, Pr, Yb, Ca, etc.) as the precursor, control the pH value of the aqueous solution to 7-10 by using NH4OH, NaOH and other alkaline reagents, precipitate the metal ions into metal hydroxide or co-precipitated gel (such as M(OH) x or mixed hydroxide), wash, dry at 110-125℃, and convert the hydroxide into oxide or oxide state stable pigment powder at 500-1200℃ for 0.5-2h.

[0019] S2: mixing zirconia powder and yellow pigment precursor for co-milling treatment; Disperse the commercial zirconia powder (such as YSZ or pure ZrO2) in water or a suitable solvent, where dispersants and grinding aids can be added, and in the co-milling (sand milling, ball milling or bead milling) stage, gradually add the pigment precursor (hydroxide or calcined pigment oxide) to the mixed slurry in a certain proportion (typically 0.1-10 wt%, which can be determined according to optimization), adjust the milling time (2-10h), milling medium (alumina or zirconia balls), ball-to-material ratio (6:1-10:1), rotation speed (200-600rpm), pH value (8-11), dispersant (polyvinyl alcohol, polyethylene glycol or polyacrylammonium, etc.), so that the pigment particles are uniformly dispersed around the zirconia particles and the grain boundaries, and are not easy to aggregate. During the co-milling process, further sampling detection (such as particle size, dispersibility, pigment distribution) can be performed to optimize the mixing and milling process.

[0020] Pigment doping adopts multi-doping or synergistic doping mode (for example, Fe + V, Pr + Fe combined doping), and an interface modifier (such as silane, phosphate ester, carboxylate) is added in a co-milling stage or a post-treatment stage to enhance the interface bonding between the pigment and the zirconia; at the same time, a color gradient or a multi-layer structure can be designed to realize a gradient color or a double-tone effect, and for specific applications, other functional doping (such as electrically conductive, luminescent, antibacterial, etc.) can be combined to assist in preparation.

[0021] S3: The slurry after co-milling treatment is dried, granulated and screened to obtain yellow zirconia powder; The slurry after co-milling is subjected to spray drying, drum drying or blow drying treatment, and after drying, if there is agglomeration or bulk body, dry grinding, ball milling or grinding is used to the required particle size, and screening is performed to remove large particle sizes or agglomerates, so as to ensure that the final powder particle size distribution meets the design requirements.

[0022] S4: The yellow zirconia powder is subjected to heat treatment to obtain yellow zirconia powder with excellent bonding strength and heat resistance stability; The powder is subjected to annealing treatment in an oxidizing atmosphere or an inert atmosphere, and the temperature is set to 500-1200 ℃. This treatment enables the pigment components to realize partial solid solution, diffusion and bonding on the surface or grain boundary of the zirconia matrix, thereby enhancing the bonding strength and heat resistance stability. The annealing temperature and holding time should be set to avoid zirconia grain coarsening or phase precipitation under the premise of ensuring color stability.

[0023] The application also provides an application of the yellow zirconia powder. The yellow zirconia powder is applied to the preparation of a ceramic material. The existing ceramic forming method (such as dry pressing, slip casting, binder assisted forming, hot isostatic pressing, etc.) is used to prepare the yellow zirconia powder into a green body or a structural part, and sintering is performed at a temperature of 1350-1600 °C, and finally a yellow zirconia ceramic material or device with uniform yellow color, dense structure and stable performance is obtained.

[0024] Example 1 Raw materials and formulations: 8YSZ powder (Y2O3 content 8wt%) is selected as the zirconia matrix, Fe(NO3)3·9H2O is selected as the Fe precursor, and an appropriate amount of solution is prepared; Fe 3+ The solution is added dropwise to 80mL water to pH=9 (adjusted with NH4OH), Fe(OH)3 precipitate is generated, and the precipitate is washed and dried to 120°C to obtain hydroxide pigment.

[0025] Co-milling and adding stage: YSZ powder was dispersed in deionized water, 0.5wt% sodium polyacrylate was added as dispersant; Fe(OH)3pigment precursor was slowly added into the slurry (2wt% addition amount); co-milling was performed using a bead mill with a bead-to-material ratio of 10:1, a milling time of 6 hours, and a rotation speed of 300 rpm.

[0026] Drying, granulation and sieving: The slurry was spray dried to a water content of <1%, and the dry powder was dry milled / ball milled to a D 50 ≈0.3 pm, sieved through a 200 mesh screen, to obtain yellow zirconia powder.

[0027] Annealing heat treatment: The powder was annealed at 900°C for 2 hours in an oxygen or air atmosphere to promote the combination and stability of the pigment and zirconia.

[0028] Forming and sintering: 1.5 g of the powder was pressed into a circular sheet with a diameter of 20 mm and a thickness of several mm at a pressure of 4 MPa, and the green body was heated to 1400°C at a rate of 1.5°C / min in a resistance furnace, and then naturally cooled after holding for 2 hours, to obtain a yellow zirconia ceramic sheet.

[0029] Performance testing: XRD analysis confirmed that the main phase was zirconia, and no obvious Fe-based precipitated phase was detected; SEM examination of the particle boundaries and pigment distribution showed no obvious particle aggregation or color spots; colorimetric determination: L* = 70.2, a* = 8.5, b* = 35.4 (example values); mechanical property testing: biaxial bending strength 950 MPa, fracture toughness 9.8 MPa-m 1 / 2 , density 6.05 g / cm³; color stability testing: color difference ΔE* <2 after holding at 1200°C for 10 hours; color difference <3 after multiple thermal cycles.

[0030] Example 2 Raw materials and ingredients: Zirconia matrix: 8YSZ powder (Y2O3 content 8wt%) Yellow pigment precursor: V(OH) x hydroxide Pigment addition amount: 3.0 wt% (relative to the mass of the zirconia powder) Dispersant: polyvinyl alcohol (PVA) 0.5 wt%; grinding aid: sodium citrate 0.2wt% Process steps: 1. Dissolve V2O5 in deionized water (500 mL) to obtain a solution; slowly add NH4OH to control the pH to 9, and precipitate V(OH) 5+ .x / Co-precipitated colloidal matter.

[0031] 2. Wash the precipitate until the conductivity is <10 µS / cm, and dry it at 110°C to obtain a yellow precursor powder.

[0032] 3. Disperse 1000g of 8YSZ powder in 2000mL of deionized water, add PVA and sodium citrate, and stir for 30min.

[0033] 4. Add the yellow precursor powder (30g) to the slurry and grind it for 5 hours using a bead mill (balls Ø5mm, ball-to-powder ratio 8:1, speed 250rpm).

[0034] 5. Remove the slurry and spray dry it (inlet temperature 200°C, outlet temperature 90°C) to obtain dry powder; pass it through a 200-mesh sieve.

[0035] 6. Anneal at 850°C for 3 hours in air atmosphere, then cool to room temperature.

[0036] 7. Dry compress the powder into sheets (specifications: Ø20 mm × 5 mm thickness, pressure 100 MPa, hold pressure for 2 min), then heat at 1400°C at a rate of 5 °C / min, hold at that temperature for 2 hours, and cool to room temperature.

[0037] Performance testing: Chromaticity (L*, a*, b*): L* = 66.1, a* = 11.5, b* = 37.2; Density: 6.04 g / cm³; Flexural strength: 930 MPa; Color ΔE* < 2.5 after 1000 thermal cycles.

[0038] Example 3 Raw materials and ingredients: Zirconia matrix: 4YSZ powder (Y2O3 content 4wt%) Yellow pigment precursor: Ce(NO3)3·6H2O + NH4OH precipitate Ce(OH)3 / coprecipitate Pigment addition amount: 1.0wt% Dispersant: Polyvinyl alcohol (PVA) 0.3wt%; Grinding aid: Polyvinyl alcohol amine (PEI) 0.1wt% Process steps: 1. Dissolve Ce(NO3)3 in 300 mL of deionized water, add NH4OH dropwise to make pH=8.5 to precipitate Ce(OH)3, wash and dry.

[0039] 2. Mix 8 wt% of dispersant (PVA) with 4YSZ powder in 1000 mL of deionized water and stir for 20 min.

[0040] 3. Add Ce(OH)3 precursor powder (10g) to the slurry and grind it for 4 hours using a bead mill (3mm beads, ball-to-material ratio 10:1, speed 300 rpm).

[0041] 4. Spray dry, and sieve the dry powder to 150 mesh.

[0042] 5. Anneal at 1000°C for 2 hours in an oxygen atmosphere.

[0043] 6. After molding (Ø25mm×4mm thickness, pressed at 120MPa), heat at 1350°C at a rate of 10°C / min and hold for 1 hour.

[0044] Performance testing: Color: L* = 68.8, a* = 10.2, b* = 35.0; Density: 6.00 g / cm³; Hardness HV ≈ 1150; Electrical resistance change after heat aging (600 °C × 500 h) <3%.

[0045] Example 4 Raw materials and ingredients: Zirconia matrix: Pure ZrO2 powder (unstabilized) Yellow pigment precursor: Mn(NO3)2 + Ca(OH)2 → Mixed precipitate Mn–Ca hydroxide Pigment addition amount: 5.0wt% Dispersant: Polyvinyl alcohol (PVA) 0.7 wt%; Grinding aid: Sodium citrate 0.4 wt%. Process steps: 1. Dissolve 5.0g Mn(NO3)2 in 200mL of water, add 3.0g Ca(OH)2 at the same time, and adjust the pH to 9 with NH4OH to precipitate Mn–Ca hydroxide.

[0046] 2. Wash and dry at 120°C.

[0047] 3. Disperse 500g of ZrO2 powder in 1000mL of deionized water, and add PVA and sodium citrate.

[0048] 4. Add precursor powder (25 g) and grind for 8 hours using a bead mill (4 mm beads, ball-to-powder ratio 9:1, speed 200 rpm).

[0049] 5. Dry, sieve (120 mesh), and then anneal at 950°C for 4 hours.

[0050] 6. Press (Ø20mm×6mm thickness, pressing 150 MPa), sinter at 1450°C for 3 hours.

[0051] Performance testing: Color: L* = 64.3, a* = 13.4, b* = 39.5; Density: 5.95 g / cm³; Fracture toughness K_IC ≈ 8.2 MPa·m 1 / 2 After 1000 heat cycles (25°C to 600°C), no cracks were found and the color remained intact.

[0052] Example 5 Raw materials and ingredients: Zirconia matrix: Ce-YSZ powder (0.5wt% Ce doping) Yellow pigment precursor: Cr₂O₃ + Mg(OH)₂ co-precipitate Mg–Cr hydroxide Pigment addition amount: 0.5 wt% Dispersant: Polyvinyl alcohol (PVA) 0.4 wt%; Grinding aid: Polyvinyl alcohol amine (PEI) 0.2 wt%. Process steps: 1. Dissolve the Cr2O3 precursor salt in water, add Mg(OH)2 solution, and precipitate Mg–Cr hydroxide.

[0053] 2. Wash and dry to obtain powder.

[0054] 3. Disperse 1 kg of Ce-YSZ powder in 2 L of deionized water, and add PVA and PEI.

[0055] 4. Add precursor powder (5g) and grind for 3 hours using a bead mill (6mm beads, ball-to-material ratio 7:1, speed 250rpm).

[0056] 5. Dry, sieve (180 mesh), and anneal at 900°C for 1 hour.

[0057] 6. Molding (Ø30mm×3 mm thick, pressing 80MPa), sintering at 1300°C for 2 hours.

[0058] Performance testing: Color: L* = 70.5, a* = 9.8, b* = 34.0; Density: 6.10 g / cm³; Hardness HV = 1250; Color change ΔE* < 1 after vibration test (frequency 50Hz, amplitude 0.5mm, duration 24h).

[0059] This invention uses pigments as pre-prepared hydroxides, which are introduced during the sand milling stage, making it easier to achieve uniform dispersion and reduce pigment aggregation and color spots. Furthermore, after annealing and solution treatment, the pigment components can be more stably bound to the zirconia matrix, reducing the risk of high-temperature volatilization, precipitation, and discoloration. In addition, this method causes little damage to the microstructure of the zirconia matrix, while still maintaining good densification ability and mechanical properties. After sintering, the ceramic has stable and uniform color and good adhesion, making it suitable for applications such as colored structural ceramics, decorative ceramics, and electronic ceramics. The process is relatively simple and easy to promote industrialization.

[0060] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing yellow zirconium oxide powder by co-milling pigment and zirconium oxide, characterized in that, Includes the following steps: S1: Preparation of yellow pigment precursor; S2: Zirconia powder is mixed with yellow pigment precursor and then co-milled. S3: The co-milled slurry is dried, granulated, and sieved to obtain yellow zirconium oxide powder; S4: Heat-treat the yellow zirconia powder to obtain yellow zirconia powder with excellent bonding strength and heat resistance.

2. The method for preparing yellow zirconium oxide powder by co-milling pigment and zirconium oxide according to claim 1, characterized in that, In step S1, one or more water-soluble metal salts corresponding to color-producing metal elements are selected as precursors; the pH is controlled at 7-10 in an aqueous solution to precipitate metal ions into metal hydroxides or co-precipitated colloids, which are then washed, dried at 110℃-125℃, and kept at 500℃-1200℃ for 0.5h-2h to convert the hydroxides into oxides or oxidized stable pigment powders.

3. The method for preparing yellow zirconium oxide powder by co-milling pigment and zirconium oxide according to claim 1, characterized in that, In step S2, commercial zirconia powder is dispersed in water or a suitable solvent. During the co-grinding stage, pigment precursors are gradually added to the mixed slurry. By adjusting the grinding time, grinding media, ball-to-particle ratio, rotation speed, pH value, and dispersant, the pigment particles are uniformly dispersed between zirconia particles and around the grain boundaries, making them less prone to aggregation.

4. The method for preparing yellow zirconium oxide powder by co-milling pigment and zirconium oxide according to claim 1, characterized in that, In step S3, the co-milled slurry is spray-dried, drum-dried, or blow-dried. If there are agglomerates or lumps after drying, they are dry-milled, ball-milled, or ground to the required particle size and then sieved to remove large particles or agglomerates, ensuring that the final powder particle size distribution meets the design requirements.

5. A method for preparing yellow zirconium oxide powder by co-milling pigment and zirconium oxide according to claim 1, characterized in that, In step S4, the powder is annealed in an oxidizing or inert atmosphere at a temperature of 500-1200 °C.

6. The method for preparing yellow zirconium oxide powder by co-milling pigment and zirconium oxide according to claim 3, characterized in that, In step S2, the grinding time is set to 2-10 hours, the grinding medium is selected as alumina or zirconia balls, the ball-to-material ratio is 6:1-10:1, the rotation speed is set to 200-600 rpm, the pH value is set to 8-11, and the dispersant is selected as polyvinyl alcohol, polyethylene glycol, or ammonium polyacrylate.

7. The method for preparing yellow zirconia powder by co-milling pigment and zirconia according to claim 3, characterized in that, In step S2, pigment doping is carried out using multi-component doping or synergistic doping methods. An interface modifier is added during the co-grinding stage or post-treatment stage to enhance the interfacial bonding between the pigment and zirconium oxide.

8. An application of yellow zirconia powder prepared by any one of claims 1-7, characterized in that, The yellow zirconia powder is used in the preparation of ceramic materials.

9. The application of the yellow zirconium oxide powder according to claim 8, characterized in that, Includes the following steps: Yellow zirconia powder is prepared into blanks or structural parts using existing ceramic forming methods, and then sintered at a temperature of 1350-1600°C to finally obtain yellow zirconia ceramic materials or devices with uniform yellow color, dense structure and stable performance.

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