A ZTA ceramic granulation powder, its preparation method and application

Abstract

This invention discloses a ZTA ceramic granulation powder, its preparation method, and its application in pressing and firing ceramic parts. The ZTA ceramic granulation powder is obtained by spray granulation of a raw material slurry comprising the following components: 80-90 parts by weight of α-Al₂O₃ powder, 10-20 parts by weight of ZrO₂ powder, 0.05-1.5 parts by weight of doped powder, 0.1-0.45 parts by weight of TiO₂ powder, 45-60 parts by weight of pure water, 0.5-2.5 parts by weight of cold-soluble polyvinyl alcohol binder, and 0.5-3.5 parts by weight of polyethylene wax emulsion; the doped powder is at least one of MgO powder, Cr₂O₃ powder, and CeO₂ powder; the TiO₂ powder is rutile titanium dioxide. The ZTA ceramic granulation powder of this invention has a round morphology, excellent flowability and bulk density. ZTA ceramic parts made from this granulation powder after pressing and high-temperature firing are white in color, exhibiting lower firing temperatures and better fracture toughness.

Description

Technical Field

[0001] This invention relates to the field of zirconia-toughened alumina (ZTA) ceramic materials, specifically to a ZTA ceramic granulation powder, its preparation method, and its application. Background Technology

[0002] ZTA ceramics consist of zirconium oxide (ZrO2) particles dispersed independently within an alumina (Al2O3) matrix. During manufacturing and use, the transformation from a tetragonal phase to a monoclinic phase occurs, accompanied by volume expansion and shear strain. This results in various toughening pathways for the zirconium oxide particles within the system, including stress-induced phase transformation toughening, microcrack toughening, and crack-directing toughening. Consequently, the fracture toughness and fracture strength of the material are significantly improved, achieving both toughening and reinforcement effects. For example, patent specification CN101508562A discloses a toughened alumina structural ceramic material with a composition of 78–85 wt% alumina, 13–20 wt% yttrium-stabilized zirconium oxide, and 0.5–2 wt% titanium dioxide; wherein the yttrium-stabilized zirconium oxide consists of 97 mol% zirconium oxide and 3 mol% yttrium oxide (Y2O3).

[0003] The preparation of ZTA ceramic materials generally includes three steps: raw material granulation, dry pressing, and high-temperature firing. In order to obtain granulated powder particles with good flowability and filling performance, a slurry + pressure or centrifugal spray drying process is adopted to obtain granulated powder particles with good sphericity. Then, the green body is formed by dry pressing or isostatic pressing and then fired at high temperature by heat treatment equipment to form dense ZTA ceramic materials.

[0004] To further improve the mechanical properties of ZTA ceramic materials, such as hardness, toughness, and strength, a certain proportion of oxides such as magnesium oxide (MgO), chromium oxide (Cr2O3), and cerium oxide (CeO2) are generally doped. Existing methods for preparing ZTA ceramic materials include "A method for preparing ZTA ceramic materials and the materials prepared therefrom" (publication number CN110015889A), which mentions doping oxides such as chromium oxide and magnesium oxide during the slurry preparation and granulation process to improve the mechanical properties of ZTA materials. However, the introduction of these oxides will cause color changes in ZTA materials. For example, the introduction of chromium oxide will make ZTA materials pink, while the introduction of magnesium oxide and cerium oxide will make ZTA materials yellow. Summary of the Invention

[0005] This invention provides a ZTA ceramic granulation powder, the raw material composition of which includes α-Al2O3 powder, ZrO2 powder, doped powder (such as MgO powder, Cr2O3 powder, CeO2 powder, etc.), TiO2 powder, pure water, cold-soluble polyvinyl alcohol (PVA) binder and polyethylene wax emulsion. It can be obtained by ball milling and spray drying. It has a round morphology and excellent flowability and bulk density. ZTA ceramic parts made by pressing and high-temperature firing of this granulation powder are white in color, effectively eliminating the discoloration problem of ZTA ceramics caused by the introduction of coloring oxides such as magnesium oxide, chromium oxide and cerium oxide. It has a lower ceramic forming temperature and better fracture toughness.

[0006] A ZTA ceramic granulation powder is obtained by spray granulation of a raw material comprising the following components:

[0007]

[0008] The doped powder is at least one of MgO powder, Cr2O3 powder, and CeO2 powder;

[0009] The TiO2 powder is rutile titanium dioxide.

[0010] In the raw material composition of the ZTA ceramic granulation powder of the present invention, if the amount of TiO2 powder added is too large, for example, more than 0.8 parts by weight, the ceramic parts obtained by high-temperature firing will have a blue color and the fracture toughness of the ceramic parts will be greatly reduced.

[0011] In some embodiments, the total weight of the α-Al2O3 powder and the ZrO2 powder in the ZTA ceramic granulation powder may be 100 parts.

[0012] In some preferred embodiments, the weight percentage of the polyethylene wax emulsion in the raw material composition of the ZTA ceramic granulation powder, based on the total weight of the α-Al2O3 powder and the ZrO2 powder as 100%, does not exceed 3.5%. When the addition ratio of polyethylene wax emulsion exceeds 3.5%, the slurry will become too thick, affecting the spray granulation performance and hindering the high-temperature firing and debinding of the molded green body, resulting in a decrease in ceramic density, toughness, strength, and other performance indicators.

[0013] In some preferred embodiments, the weight ratio of α-Al2O3 powder to ZrO2 powder in the raw material composition of the ZTA ceramic granulation powder of the present invention is 85:15. Under this condition, the fracture toughness index of the ceramic material obtained by final firing reaches the optimal value, and the mechanical properties such as ceramic density and hardness are at the optimal and moderate value of the formula.

[0014] In some preferred embodiments, in the raw material composition of the ZTA ceramic granulation powder of the present invention, the mass ratio of the doped powder to the TiO2 powder is 0.8:0.25 to 0.35, and may be further 0.8:0.3, which is beneficial to improving the comprehensive properties of the sintered ceramic, such as density, hardness, and fracture toughness.

[0015] In some embodiments, the ZrO2 powder in the ZTA ceramic granulation powder can be a ZrO2 powder with a molar ratio of 2% to 5% that is stable with Y2O3.

[0016] In some embodiments, the ZTA ceramic granulated powder is in the form of regular spheres, with a flowability of 60-70 s / 50g and a bulk density of 1.2-1.3 g / cm³. 3 .

[0017] This invention also provides a method for preparing the ZTA ceramic granulated powder, comprising the following steps:

[0018] 1) Add pure water to the ball mill equipment;

[0019] 2) Add the polyethylene wax emulsion to the pure water medium in step 1);

[0020] 3) Add α-Al2O3 powder, ZrO2 powder, doped powder and TiO2 powder to the mixing medium in step 2), and turn on the ball mill to ball mill and prepare the slurry;

[0021] 4) Once the slurry in the ball mill reaches the required particle size, add the cold-soluble polyvinyl alcohol binder to the slurry and continue ball milling. Once the cold-soluble polyvinyl alcohol binder is completely dissolved and dispersed, the ball milling process is complete.

[0022] 5) The slurry obtained in step 4) is spray-granulated through a pressure spray drying tower to obtain spherical ZTA ceramic granulated powder.

[0023] In the preparation method described above, the ball milling equipment can be a vertical stirred mill, and the wall of the vertical mill barrel and the stirring rod can be lined with wear-resistant polyurethane.

[0024] In the preparation method described above, step 5) uses a 0.8-1.8 mm spray nozzle and a spray pressure of 1.5-3.0 MPa.

[0025] This invention also provides the application of the ZTA ceramic granulation powder in the pressing and firing of ceramic parts. The ceramic parts are white in color. Furthermore, the fracture toughness of the ceramic parts is greater than 5.2 MPa / m. 1 / 2 It can reach 5.95 MPa m 1 / 2 The firing temperature may not exceed 1560℃.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. This invention effectively eliminates the discoloration problem of ZTA ceramic parts caused by the introduction of TiO2 powder in specific proportions and crystal forms. The granulated powder prepared is used to form ceramic parts that are white after pressing and high-temperature firing.

[0028] 2. By introducing TiO2 powder in specific proportions and crystal forms, this invention can significantly reduce the ceramic forming temperature of ZTA ceramic parts by 30-50°C, and increase the fracture toughness of the ceramic material to ≥5.95 MPa. 1 / 2 The fracture toughness index was improved by more than 20%.

[0029] 3. This invention uses a cold-soluble PVA binder to replace the traditional hot-water-soluble adhesive PVA, which can be directly added to the slurry in dry powder form, shortening the slurry preparation process by 1 / 3.

[0030] 4. This invention uses polyethylene wax emulsion as a supplementary agent for cold-soluble PVA binders, effectively solving the problem of insufficient strength in cold-soluble PVA binders. It also optimizes the morphology of apple-shaped and sunken particles that are easily produced in conventional binder spray granulation. The granulated powder exhibits good sphericity and roundness, fast flowability (60-70s / 50g), and high bulk density (1.2-1.3g / cm³). 3 Features such as ) Detailed Implementation

[0031] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Operating methods not specifically specified in the following embodiments are generally performed under conventional conditions or as recommended by the manufacturer. Unless otherwise specified, the TiO2 powder used in the following embodiments and comparative examples is rutile titanium dioxide.

[0032] Example 1

[0033] The raw materials were weighed according to the following ratio: 80 parts by weight of α-Al₂O₃ powder, 20 parts by weight of ZrO₂ powder stabilized by Y₂O₃ (5% molar ratio), 0.8 parts by weight of MgO powder, 0.10 parts by weight of TiO₂ powder, 50 parts by weight of pure water, 1.5 parts by weight of cold-soluble PVA binder, and 2.0 parts by weight of polyethylene wax emulsion. The specific preparation steps are as follows:

[0034] (1) First, add pure water to the ball mill equipment;

[0035] (2) Add the polyethylene wax emulsion to the pure water medium in step (1);

[0036] (3) Add α-Al2O3 powder, ZrO2 powder, MgO powder and TiO2 powder to the medium in step (2) and start the ball mill to make ball mill slurry;

[0037] (4) When the slurry from step (3) reaches the expected particle size, the cold-soluble PVA binder is added to the slurry from step (3) and ball milling is continued.

[0038] (5) When the cold-soluble PVA binder in step (4) is completely dissolved and dispersed, the ball milling pulping is completed;

[0039] (6) Using a 0.8mm spray nozzle and a spray pressure of 3.0MPa, the slurry prepared in step (5) is sprayed and granulated through a pressure spray drying tower to obtain ZTA ceramic granulated powder.

[0040] The prepared granulated powder exhibits good sphericity and roundness, a flowability of 60s / 50g, and a high bulk density of 1.3g / cm³. 3 The granulated powder, after being pressed into a compact and fired at 1560℃, produces a white ceramic piece with a density of 4.32 g / cm³. 3 Vickers hardness 1757 HV, fracture toughness 5.50 MPa 1 / 2 .

[0041] Example 2

[0042] The raw materials were weighed according to the following ratio: 85 parts by weight of α-Al₂O₃ powder, 15 parts by weight of ZrO₂ powder stabilized by Y₂O₃ (3.5% molar ratio), 0.8 parts by weight of Cr₂O₃ powder, 0.3 parts by weight of TiO₂ powder, 60 parts by weight of pure water, 0.5 parts by weight of cold-soluble PVA binder, and 0.5 parts by weight of polyethylene wax emulsion. The specific preparation steps are as follows:

[0043] (1) First, add pure water to the ball mill equipment;

[0044] (2) Add the polyethylene wax emulsion to the pure water medium in step (1);

[0045] (3) Add α-Al2O3 powder, ZrO2 powder, Cr2O3 powder and TiO2 powder to the medium in step (2) and start the ball mill to make ball mill slurry;

[0046] (4) When the slurry from step (3) reaches the expected particle size, add the cold-soluble PVA binder into the slurry from step (3) and continue ball milling to make slurry;

[0047] (5) When the cold-soluble PVA binder in step (4) is completely dissolved and dispersed, the ball milling pulping is completed;

[0048] (6) Using a 0.8mm spray nozzle and a spray pressure of 3.0MPa, the slurry prepared in step (5) is sprayed and granulated through a pressure spray drying tower to obtain ZTA ceramic granulated powder.

[0049] The prepared granulated powder exhibits good sphericity and roundness, a flowability of 65s / 50g, and a high bulk density of 1.2g / cm³. 3 The granulated powder, after being pressed into a compact and fired at 1560℃, produces a white ceramic piece with a density of 4.35 g / cm³. 3 Vickers hardness 1768 HV, fracture toughness 5.95 MPa 1 / 2 .

[0050] Example 3

[0051] The raw materials were weighed according to the following ratio: 90 parts by weight of α-Al₂O₃ powder, 10 parts by weight of ZrO₂ powder stabilized by 2% molar ratio of Y₂O₃, 0.8 parts by weight of CeO₂ powder, 0.45 parts by weight of TiO₂ powder, 45 parts by weight of pure water, 2.5 parts by weight of cold-soluble PVA binder, and 3.5 parts by weight of polyethylene wax emulsion. The specific preparation steps are as follows:

[0052] (1) First, add pure water to the ball mill equipment;

[0053] (2) Add the polyethylene wax emulsion to the pure water medium in step (1);

[0054] (3) Add α-Al2O3 powder, ZrO2 powder, CeO2 powder and TiO2 powder to the medium in step (2) and start the ball mill to make ball mill slurry;

[0055] (4) When the slurry in step (3) reaches the expected particle size, the cold-soluble PVA binder is added to the slurry in step (3) and ball milling is continued.

[0056] (5) When the cold-soluble PVA binder in step (4) is completely dissolved and dispersed, the ball milling pulping is completed;

[0057] (6) Using a 1.8mm spray nozzle and a 1.5MPa spray pressure, the slurry prepared in step (5) is sprayed and granulated through a pressure spray drying tower to obtain ZTA ceramic granulated powder.

[0058] The prepared granulated powder exhibits good sphericity and roundness, a flowability of 70s / 50g, and a high bulk density of 1.2g / cm³. 3 The granulated powder, after being pressed into a compact and fired at 1560℃, produces a white ceramic piece with a density of 4.30 g / cm³. 3 Vickers hardness 1735 HV, fracture toughness 5.21 MPa 1 / 2 .

[0059] Example 4

[0060] The only difference from Example 2 is that the TiO2 powder is 0.1 parts by weight, and everything else is the same.

[0061] The prepared granulated powder exhibits good sphericity and roundness, a flowability of 65s / 50g, and a high bulk density of 1.2g / cm³. 3 The granulated powder, after being pressed into a compact and fired at 1560℃, produces a white ceramic piece with a density of 4.32 g / cm³. 3 Vickers hardness 1760 HV, fracture toughness 5.65 MPa 1 / 2 .

[0062] Example 5

[0063] The only difference from Example 2 is that the TiO2 powder is 0.45 parts by weight; all other aspects are the same.

[0064] The prepared granulated powder exhibits good sphericity and roundness, a flowability of 65s / 50g, and a high bulk density of 1.2g / cm³. 3 The granulated powder, after being pressed into a compact and fired at 1560℃, produces a white ceramic piece with a density of 4.30 g / cm³. 3 Vickers hardness 1755 HV, fracture toughness 5.55 MPa 1 / 2 .

[0065] Comparative Example 1

[0066] The only difference from Example 2 is that TiO2 powder is not added; all other aspects are the same.

[0067] The prepared granulated powder exhibited good sphericity and roundness, a flowability of 62s / 50g, and a bulk density of 1.2g / cm³. 3 After being pressed into a compact, the granulated powder needs to be fired at 1600℃. The resulting ceramic pieces are pink in color and have a density of 4.30 g / cm³. 3 Vickers hardness 1710 HV, fracture toughness 4.85 MPa 1 / 2 .

[0068] Comparative Example 2

[0069] The only difference from Example 3 is that the TiO2 powder is 0.85 parts by weight; all other aspects are the same.

[0070] The prepared granulated powder exhibits good sphericity and roundness, a flowability of 70s / 50g, and a high bulk density of 1.2g / cm³. 3 The granulated powder, after being pressed into a compact and fired at 1560℃, produces a porcelain piece with a light blue hue and a density of 4.15 g / cm³. 3 Vickers hardness 1650 HV, fracture toughness 4.35 MPa 1 / 2 .

[0071] Comparative Example 3

[0072] The only difference from Example 1 is that polyethylene wax emulsion is not added; all other aspects are the same.

[0073] The prepared granulated powder particles are in the form of apple-shaped or concave particles, with a flowability of 80s / 50g and a loose packing density of 1.10g / cm³. 3 The granulated powder, after being pressed into a compact and fired at 1560℃, produces a white ceramic piece with a density of 4.28 g / cm³. 3 Vickers hardness 1735 HV, fracture toughness 5.35 MPa 1 / 2 .

[0074] Comparative Example 4

[0075] The only difference from Example 1 is that the polyethylene wax emulsion is 5.0 parts by weight, and all other components are the same.

[0076] The prepared granulated powder exhibits good sphericity and roundness, a flowability of 75s / 50g, and a bulk density of 1.15g / cm³. 3 The granulated powder, after being pressed into a compact and fired at 1560℃, produces a white ceramic piece with a density of 4.20 g / cm³. 3 Vickers hardness 1680 HV, fracture toughness 5.10 MPa 1 / 2 .

[0077] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A ZTA ceramic granulation powder, characterized by, Obtained by spray granulation of raw materials comprising the following components: 80-90 parts by weight of α-Al₂O₃ powder 10-20 parts by weight of ZrO2 powder The doped powder is 0.05~1.5 parts by weight. TiO2 powder, 0.1~0.45 parts by weight, 45-60 parts by weight of pure water Cold-soluble polyvinyl alcohol binder, 0.5~2.5 parts by weight. Polyethylene wax emulsion, 0.5~3.5 parts by weight; The doped powder is at least one of MgO powder, Cr2O3 powder, and CeO2 powder; The TiO2 powder is rutile titanium dioxide. The mass ratio of the doped powder to the TiO2 powder is 0.8:0.3; Based on the total weight of the α-Al2O3 powder and the ZrO2 powder being 100%, the weight percentage of the polyethylene wax emulsion is no more than 3.5%.

2. The ZTA ceramic granulation powder according to claim 1, characterized in that, The weight ratio of the α-Al2O3 powder to the ZrO2 powder is 85:15; The total weight of the α-Al2O3 powder and the ZrO2 powder is 100 parts.

3. The ZTA ceramic granulation powder according to claim 1 or 2, characterized in that, The ZrO2 powder is a ZrO2 powder with a molar ratio of 2% to 5% that is stable with Y2O3.

4. The ZTA ceramic granulation powder of claim 1, wherein, The ZTA ceramic granulation powder is regular spherical shape, the fluidity is 60-70 s / 50 g, the loose bulk density is 1.2-1.3 g / cm 3 .

5. The method of producing a ZTA ceramic granulation powder according to any one of claims 1 to 4, characterized by, Including the following steps: 1) Add pure water to the ball mill equipment; 2) Add the polyethylene wax emulsion to the pure water medium in step 1); 3) Add α-Al2O3 powder, ZrO2 powder, doped powder and TiO2 powder to the mixed medium in step 2), and turn on the ball mill to ball mill and prepare the slurry; 4) Once the slurry in the ball mill reaches the required particle size, add the cold-soluble polyvinyl alcohol binder to the slurry and continue ball milling. Once the cold-soluble polyvinyl alcohol binder is completely dissolved and dispersed, the ball milling process is complete. 5) The slurry obtained in step 4) is spray-granulated through a pressure spray drying tower to obtain spherical ZTA ceramic granulated powder.

6. The production method according to claim 5, wherein The ball mill equipment is a vertical stirred mill, with the vertical mill barrel wall and stirring rod lined with wear-resistant polyurethane.

7. The preparation method according to claim 5, characterized in that, In step 5), the pressure sprayer uses a 0.8~1.8mm spray nozzle and a spray pressure of 1.5~3.0 MPa.

8. The application of the ZTA ceramic granulation powder according to any one of claims 1 to 4 in the pressing and firing of ceramic parts, characterized in that, The porcelain piece is white in color.

9. The application according to claim 8, characterized in that, The ceramic piece has a fracture toughness greater than 5.2 MPa m 1 / 2 .

10. The application according to claim 8, characterized in that, The firing temperature shall not exceed 1560°C.

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