Black zirconia ceramic temperature measuring probe handle and preparation method

Abstract

This invention discloses a black zirconia ceramic temperature probe handle and its preparation method, belonging to the field of ceramic materials technology. The invention involves the following steps: mixing 3 mol% yttrium-stabilized zirconia powder with a black pigment, refining the mixture to nanoscale through sand milling, adding paraffin wax and beeswax, hot-pressing and molding the handle, and integrally forming the internal thread using a rotary unscrewing structure. After wax removal and calcination, the handle is sintered at high temperature in a reducing atmosphere or vacuum environment, and finally polished to a mirror-like surface. The black zirconia ceramic prepared by this invention possesses a single tetragonal phase structure, high blackness, high hardness, and high fracture toughness, and because it does not contain conductive components, it does not shield electromagnetic signals. This invention solves the problems of uneven coloring, decreased mechanical properties, and difficulty in forming complex structures in existing technologies, and is suitable for wireless temperature probe shells in fields such as intelligent barbecue equipment and food processing.

Description

Technical Field

[0001] This invention belongs to the field of ceramic material preparation technology, specifically a black zirconia ceramic temperature probe handle and its preparation method. Background Technology

[0002] Black zirconia ceramics, due to their combination of the excellent properties of zirconia ceramics such as high hardness, high toughness, wear resistance, and corrosion resistance, as well as the unique aesthetic effect of black, have broad application prospects in high-end consumer electronics, precision machinery, medical devices and other fields.

[0003] In smart barbecue equipment, the temperature probe handle serves as a protective shell for internal electronic components (temperature sensor, wireless module, battery, etc.), operating in extremely harsh environments. As shown in the product catalog, these probes need to be used long-term in gas ovens, electric ovens, charcoal ovens, pizza ovens, and other similar equipment, where ambient temperatures can reach over 300℃ (700℃ on the surface of a pizza oven stone). They must also withstand corrosive substances such as grease, salt, and acidic sauces, and are subject to frequent plugging / unplugging and high risks of drops. Furthermore, the handle material must not shield electromagnetic signals to ensure stable Bluetooth or Wi-Fi signal transmission to the mobile app. Therefore, developing a manufacturing process for a black zirconia ceramic handle that is high-temperature resistant, corrosion-resistant, drop-resistant, and does not shield signals is of great significance.

[0004] Currently, the preparation of black zirconia ceramic handles mainly employs solid-state mixing coloring and carburizing coloring methods. Solid-state mixing coloring involves mechanically mixing black pigment with zirconia matrix powder, followed by molding and sintering. This method is simple, but differences in particle size and density between the pigment and matrix powder lead to uneven mixing, easily causing particle agglomeration, resulting in uneven coloring and inconsistent internal structure. This affects the handle's appearance consistency and mechanical properties, and makes it prone to breakage at threaded joints or thin-walled areas. Carburizing coloring involves treating the zirconia green body at high temperature in a carbon-containing atmosphere, allowing carbon elements to diffuse into the surface to form a black coloring layer. This method can achieve high blackness, but the coloring layer depth is limited. After threading and polishing, the handle easily reveals the internal natural color, causing a "white showing" defect. Furthermore, the carburizing process is energy-intensive, time-consuming, and may introduce free carbon, affecting density and strength.

[0005] Furthermore, existing molding processes struggle to balance complex structures with production efficiency. Dry pressing is difficult to directly produce hollow, internally threaded handles, resulting in high subsequent machining costs and difficulty in guaranteeing thread accuracy. While injection molding can form complex shapes, internally threaded structures often require secondary processing, making it difficult to achieve one-piece molding and smooth threads.

[0006] Therefore, existing technologies suffer from problems such as uneven coloring, decreased mechanical properties, shallow carburized coloring layers that easily expose the white layer, complex processes, and high energy consumption, making it difficult to meet the comprehensive requirements of intelligent barbecue equipment for probe handles with high blackness, consistent internal and external color, no signal shielding, and high temperature and corrosion resistance. There is an urgent need to develop a manufacturing process for black zirconia ceramic handles that features uniform color, controllable blackness, excellent mechanical properties, and the ability to integrally mold complex structures. Summary of the Invention

[0007] The purpose of this invention is to provide a black zirconia ceramic temperature probe handle and its preparation method to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides a method for preparing a black zirconia ceramic temperature probe handle, comprising the following steps: S1. Powder mixing: By mass, take 950-980 parts of 3 mol% yttrium oxide partially stabilized zirconium oxide powder (3Y-PSZ or 3YSZ) and 2-5 parts of black pigment, wherein the black pigment is composed of CoO, NiO and Fe2O3 in a mass ratio of 0.5-1:14-18:32-36; S2. Sand milling and refining: Add 0.25-0.45% of a dispersant by weight of the total powder to the mixture, and mill at 1500-2000 r / min for 3-6 hours until the powder particle size D is reached. 50 ≤80nm, to obtain sand-milled powder; S3. Hot pressing molding: Add 12%-18% paraffin wax and 0.5%-1% beeswax by weight of the sand-milled powder, stir at 80-120℃ for 2-3 hours, transfer to a vacuum mixing tank and stir for 0.5 hours to remove air bubbles, pour the slurry at 65-80℃ into the hot pressing machine, and hot press mold it under 0.5-0.8MPa air pressure, and use a rotary unscrewing structure to integrally mold the internal thread of the connecting end to obtain a hollow integral molded green blank; S4. Wax removal and bisque firing: The shaped green body is placed in a wax removal kiln, heated to 800-1000℃ for 50-70 hours, and held for 3-5 hours to obtain gray bisque fired pieces; S5. High-temperature sintering: Place the gray sintered part in a sintering furnace and heat it to 1350-1550℃ at a heating rate of 2-5℃ / min under a reducing atmosphere or vacuum environment, and hold it for 3-5 hours to obtain a black zirconia ceramic handle. S6. Surface polishing: The black zirconia ceramic handle is first rough polished and then fine polished for 24-30 hours each, so that its surface roughness Ra≤0.02μm.

[0009] Preferably, in step S2, the dispersant is one or more of CMC, PVA, and oleic acid.

[0010] Preferably, in step S2, the grinding and refining process uses 0.1-0.8mm zirconia beads as grinding media, with a ball-to-material ratio of 1:3.

[0011] Preferably, in step S5, the reducing atmosphere is hydrogen or a mixture of hydrogen and nitrogen.

[0012] Preferably, in step S6, during coarse polishing, a 95% alumina ceramic column with a diameter of 5mm and a length of 10mm and silicon carbide sand with a particle size of 40-100 mesh are added; during fine polishing, a talc ceramic column with a diameter of 5mm and a length of 10mm, 320-mesh alumina micro powder, polishing liquid, and brightener are added.

[0013] A black zirconia ceramic temperature probe handle is also provided, which is prepared by the method described above. The handle is a hollow, one-piece molded structure, and its connecting end is provided with an internal thread.

[0014] Preferably, the black zirconia ceramic has a single tetragonal phase structure, a blackness value of 110-200, a hardness of 14.6-15 GPa, and a fracture toughness of 12-13 MPa·m. 1 / 2 Furthermore, because it does not contain conductive components, it does not shield electromagnetic signals.

[0015] Compared with the prior art, the beneficial effects of the present invention are: ① This invention controls the particle size of the powder to ≤80nm through sand milling and combines it with a specific ratio of compound colorant to achieve atomic-level uniform mixing of colorant and matrix, thus solving the problem of uneven coloring in traditional solid-phase mixing method; reducing atmosphere sintering allows the colorant ions to be fully dissolved, resulting in consistent color inside and outside the handle, with a blackness value of 110-200, and it does not fade or peel at high temperature.

[0016] ②This invention uses 3 mol% yttrium oxide to partially stabilize zirconium oxide, which forms a single tetragonal phase structure after sintering, fully utilizing the phase transformation toughening mechanism. The hardness and fracture toughness are significantly superior to traditional coloring processes, making it less prone to breakage in scenarios such as frequent insertion / removal and accidental drops.

[0017] ③ This invention combines hot die casting with a rotary unscrewing structure to achieve integrated molding of the hollow handle structure and the internal thread of the connecting end; no secondary processing is required, the thread size is accurate, complete and smooth, avoiding assembly jamming or poor sealing problems, and improving product yield and production efficiency.

[0018] ④ The black zirconia ceramic prepared by this invention does not contain conductive components and does not shield electromagnetic signals, ensuring that the signal of the wireless transmission module inside the handle is stably transmitted to the mobile APP, thus meeting the requirements of smart barbecue equipment for wireless transmission reliability. Attached Figure Description

[0019] Figure 1This is a flowchart illustrating the preparation method of a black zirconia ceramic temperature probe handle according to the present invention. Figure 2 A three-dimensional structural diagram of a handle for a black zirconia ceramic temperature probe; Figure 3 for Figure 2 The cross-sectional view of the handle of the black zirconia ceramic temperature probe is shown. In the diagram: 1. Handle body; 2. Internal thread. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1 like Figure 1 As shown in the figure, this embodiment provides a method for preparing a handle for a black zirconia ceramic temperature probe. The specific steps are as follows: S1, Powder Mixing Based on mass parts, 965 parts of 3 mol% yttrium oxide partially stabilized zirconium oxide powder (specific surface area 11.2 m²) were taken. 2 / g,D 50 =0.18μm) and 3.5 parts of black pigment. The black pigment is composed of CoO, NiO and Fe2O3 in a mass ratio of 0.8:16:34. The above powders are put into a three-dimensional mixer and mixed for 2 hours to allow the components to be initially and evenly dispersed.

[0022] S2, Grinding and Refining Oleic acid (0.35% by weight of total powder mass) was added to the mixture as a dispersant, and deionized water was added to prepare a slurry with a solid content of 45%. A circulating sand mill was used for sand milling, with 0.5mm diameter zirconia beads as the grinding media, a ball-to-powder ratio of 1:3, a milling speed of 1800 r / min, and a milling time of 4.5 h. After sand milling, the particle size was measured using a laser particle size analyzer, and the powder particle size D... 50 The particle size is 72nm, meeting the requirement of ≤80nm. The sand-milled slurry is spray-dried to obtain the sand-milled powder.

[0023] S3, Hot pressing molding Add 15% paraffin wax and 0.8% beeswax by weight of the sand-ground powder, and stir at 100℃ for 2.5 hours to ensure the wax fully coats the powder. Transfer the mixture to a vacuum mixing tank and stir at -0.08MPa vacuum for 0.5 hours to remove air bubbles from the slurry. Maintain the slurry temperature at 72℃, pour it into a hot press casting machine, and hot press cast it under 0.65MPa pressure. Simultaneously, use a rotary unscrewing structure to integrally form the internal thread of the connecting end, resulting in a hollow, integrally formed green blank. Testing showed that the thread accuracy met GB / T 197-2018 standard, and the surface was smooth and burr-free.

[0024] S4, Wax-removed bisque calcination The shaped green body was placed in a dewaxing kiln and heated from room temperature to 200℃ at a rate of 15℃ / h, and held for 2 hours; then heated to 500℃ at a rate of 10℃ / h, and held for 2 hours; finally heated to 900℃ at a rate of 50℃ / h, and held for 4 hours. The total dewaxing time was 60 hours. After cooling, a gray bisque was obtained. The bisque was free of cracks and deformation.

[0025] S5, High-temperature sintering The gray sintered part was placed in a vacuum sintering furnace and evacuated to a vacuum level of 1×10⁻⁶. -2 Pa was heated to 1450℃ at a heating rate of 3℃ / min, held at that temperature for 4 hours, and then cooled with the furnace to obtain a black zirconia ceramic temperature probe handle.

[0026] S6, Surface Polishing The sintered black zirconia ceramic handle was placed in a specialized polishing machine for initial rough polishing: a 5mm diameter, 10mm long alumina ceramic column and 60-mesh silicon carbide sand were added, and polishing was performed for 26 hours. Then, a fine polishing was performed: a 5mm diameter, 10mm long talc ceramic column, 320-mesh alumina powder, polishing slurry, and brightener were added, and polishing was performed for 26 hours. After polishing, the surface roughness Ra was measured using a surface roughness meter and found to be 0.015μm.

[0027] like Figure 2 and Figure 3 As shown, this embodiment also provides a black zirconia ceramic temperature probe handle, which is prepared by the above method. The handle includes a hollow, one-piece molded handle body 1, and its connecting end is provided with an internal thread 2.

[0028] Testing revealed that the black zirconia ceramic possesses a single tetragonal phase structure (without monoclinic or cubic phases). Using an X-Rite Ci64 colorimeter under a D65 light source and a 10° viewing angle, it exhibited a blackness value of 156, a hardness of 14.8 GPa, and a fracture toughness of 12.5 MPa·m. 1 / 2 Furthermore, because it does not contain conductive components, it does not shield electromagnetic signals.

[0029] In this invention, the blackness value is measured using an X-Rite Ci64 colorimeter under a D65 light source and a 10° viewing angle, and the instrument reading is taken (not the CIE Lab L* value). The higher the value, the blacker the black.

[0030] Example 2 This embodiment is basically the same as Embodiment 1, except that a lower amount of pigment and a lower sintering temperature are used to verify the implementation effect of the present invention under parameter boundary conditions.

[0031] S1, Powder Mixing Take 950 parts by weight of 3 mol% yttrium oxide partially stabilized zirconium oxide powder (specific surface area 9.5 m² / g, D 50 =0.25μm) and 2.0 parts of black pigment. The black pigment is composed of CoO, NiO and Fe2O3 in a mass ratio of 0.5:14:32. The above powders are put into a three-dimensional mixer and mixed for 1.5h.

[0032] S2, Grinding and Refining CMC (0.25% by weight of total powder mass) was added to the mixture as a dispersant, and deionized water was added to prepare a slurry with a solid content of 40%. A circulating sand mill was used for sand milling, with 0.8mm diameter zirconia beads as the grinding media, a ball-to-powder ratio of 1:3, a milling speed of 1500 r / min, and a milling time of 6 hours. After sand milling, the particle size was measured using a laser particle size analyzer, and the powder particle size D... 50 The particle size is 78nm, meeting the requirement of ≤80nm. The sand-milled slurry is spray-dried to obtain the sand-milled powder.

[0033] S3, Hot pressing molding Add 12% paraffin wax and 0.5% beeswax by weight of the sand-ground powder, and stir at 80℃ for 3 hours to ensure the wax fully coats the powder. Transfer the mixture to a vacuum mixing tank and stir at -0.08MPa vacuum for 0.5 hours to remove air bubbles from the slurry. Maintain the slurry temperature at 65℃, pour it into a hot press casting machine, and hot press cast it under 0.5MPa pressure. Simultaneously, use a rotary unscrewing structure to integrally form the internal thread of the connecting end, resulting in a hollow, integrally formed green blank.

[0034] S4, Wax-removed bisque calcination The shaped green body was placed in a dewaxing kiln and heated from room temperature to 200℃ at a rate of 12℃ / h, and held for 2 hours; then heated to 500℃ at a rate of 8℃ / h, and held for 2 hours; finally heated to 800℃ at a rate of 40℃ / h, and held for 5 hours, for a total dewaxing time of 70 hours. After cooling, a gray bisque was obtained.

[0035] S5, High-temperature sintering The gray sintered part was placed in a hydrogen atmosphere sintering furnace (hydrogen purity 99.99%) and heated to 1350℃ at a heating rate of 2℃ / min. It was held at that temperature for 5 hours and then cooled with the furnace to obtain the handle of the black zirconia ceramic temperature probe.

[0036] S6, Surface Polishing The sintered black zirconia ceramic handle was subjected to rough polishing and fine polishing for 30 hours each, using the same polishing process as in Example 1. After polishing, the surface roughness Ra was measured using a surface roughness meter and found to be 0.018 μm.

[0037] Performance testing Using the same testing method as in Example 1, the properties of the handle prepared in this example were measured as follows: blackness value 112, hardness 14.6 GPa, and fracture toughness 12.1 MPa·m. 1 / 2 It has a single tetragonal phase structure and does not shield electromagnetic signals.

[0038] Example 3 This embodiment is basically the same as Embodiment 1, except that a higher amount of pigment and a higher sintering temperature are used to verify the implementation effect of the present invention under parameter boundary conditions.

[0039] S1, Powder Mixing Take 980 parts by weight of 3 mol% yttrium oxide partially stabilized zirconium oxide powder (specific surface area 13 m² / g, D 50 =0.12μm) and 5.0 parts of black pigment. The black pigment is composed of CoO, NiO and Fe2O3 in a mass ratio of 1:18:36. The above powders are put into a three-dimensional mixer and mixed for 2.5 hours.

[0040] S2, Grinding and Refining PVA (0.45% by weight of total powder mass) was added to the mixture as a dispersant, and deionized water was added to prepare a slurry with a solid content of 50%. A circulating sand mill was used for sand milling, with 0.1 mm diameter zirconia beads as the grinding media, a ball-to-powder ratio of 1:3, a milling speed of 2000 r / min, and a milling time of 3 hours. After sand milling, the particle size was measured using a laser particle size analyzer, and the particle size D... 50 The particle size is 65nm, meeting the requirement of ≤80nm. The sand-milled slurry is spray-dried to obtain the sand-milled powder.

[0041] S3, Hot pressing molding Add 18% paraffin wax and 1.0% beeswax by weight of the sand-ground powder, and stir at 120℃ for 2 hours to ensure the wax fully coats the powder. Transfer the mixture to a vacuum mixing tank and stir at -0.08MPa vacuum for 0.5 hours to remove air bubbles from the slurry. Maintain the slurry temperature at 80℃, pour it into a hot press casting machine, and hot press cast it under 0.8MPa pressure. Simultaneously, use a rotary unscrewing structure to integrally form the internal thread of the connecting end, resulting in a hollow, integrally formed green blank.

[0042] S4, Wax-removed bisque calcination The shaped green body was placed in a dewaxing kiln and heated from room temperature to 200℃ at a rate of 18℃ / h, and held for 2 hours; then heated to 500℃ at a rate of 12℃ / h, and held for 2 hours; finally heated to 1000℃ at a rate of 60℃ / h, and held for 3 hours, for a total dewaxing time of 50 hours. After cooling, a gray bisque-fired piece was obtained.

[0043] S5, High-temperature sintering The gray sintered part was placed in a sintering furnace with a mixed atmosphere of hydrogen and nitrogen (H2:N2=5:95) and heated to 1550℃ at a heating rate of 5℃ / min. It was held at that temperature for 3 hours and then cooled with the furnace to obtain the handle of the black zirconia ceramic temperature probe.

[0044] S6, Surface Polishing The sintered black zirconia ceramic handle was subjected to rough polishing and fine polishing for 24 hours each, using the same polishing process as in Example 1. After polishing, the surface roughness Ra was measured using a surface roughness meter and found to be 0.012 μm.

[0045] Performance testing Using the same testing method as in Example 1, the properties of the handle prepared in this example were measured as follows: blackness value 198, hardness 15.0 GPa, and fracture toughness 12.8 MPa·m. 1 / 2 It has a single tetragonal phase structure and does not shield electromagnetic signals.

[0046] Comparative Example 1 To verify the beneficial effects of the present invention, a black zirconia ceramic handle was prepared using the traditional solid-phase mixing coloring method as a comparative example.

[0047] Preparation method: Take 965 parts of 3 mol% yttrium oxide partially stabilized zirconium oxide powder (specific surface area 11.2 m² / g, D 50 =0.18μm), 3.5 parts of black pigment (same ratio as in Example 1), were dry ball milled for 12 hours at 300 r / min using a planetary ball mill. After sieving, 15% of paraffin wax and 0.8% of beeswax by weight of the powder were added. The mixture was hot-pressed and cast into shape. After wax removal, it was sintered in air at 1450℃ for 4 hours and polished to the same surface roughness.

[0048] Performance testing Using the same testing method as in Example 1, the properties of the handle prepared in Comparative Example 1 were measured as follows: blackness value 89 (gray-black spots on the surface, gray-white inside), hardness 12.3 GPa, and fracture toughness 8.7 MPa·m. 1 / 2 Its crystal structure is tetragonal phase with a small amount of monoclinic phase, and it does not shield electromagnetic signals.

[0049] Table 1: Performance comparison of the handles prepared in Examples 1-3 and Comparative Example 1

[0050] 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 a handle for a black zirconia ceramic temperature probe, characterized in that, Includes the following steps: S1. Powder mixing: By mass, take 950-980 parts of 3mol% yttrium oxide partially stabilized zirconium oxide powder and 2-5 parts of black pigment, wherein the black pigment is composed of CoO, NiO and Fe2O3 in a mass ratio of 0.5-1:14-18:32-36; S2, sand grinding: adding 0.25-0.45% of the total mass of the powder of dispersant to the mixture, sand grinding at 1500-2000r / min for 3-6h, until the powder particle size D 50 ≤80nm, obtaining sand grinding powder; S3. Hot pressing molding: Add 12%-18% paraffin wax and 0.5%-1% beeswax by weight of the sand-milled powder, stir at 80-120℃ for 2-3 hours, transfer to a vacuum mixing tank and stir for 0.5 hours to remove air bubbles, pour the slurry at 65-80℃ into the hot pressing machine, and hot press mold it under 0.5-0.8MPa air pressure, and use a rotary unscrewing structure to integrally mold the internal thread of the connecting end to obtain a hollow integral molded green blank; S4. Wax removal and bisque firing: The shaped green body is placed in a wax removal kiln, heated to 800-1000℃ for 50-70 hours, and held for 3-5 hours to obtain gray bisque fired pieces; S5. High-temperature sintering: Place the gray sintered part in a sintering furnace and heat it to 1350-1550℃ at a heating rate of 2-5℃ / min under a reducing atmosphere or vacuum environment, and hold it for 3-5 hours to obtain a black zirconia ceramic handle. S6. Surface polishing: The black zirconia ceramic handle is first rough polished and then fine polished for 24-30 hours each, so that its surface roughness Ra≤0.02μm.

2. The method for preparing a black zirconia ceramic temperature probe handle according to claim 1, characterized in that, In step S2, the dispersant is one or more of CMC, PVA, and oleic acid.

3. The method for preparing a black zirconia ceramic temperature probe handle according to claim 1, characterized in that, In step S2, the grinding process uses 0.1-0.8mm zirconia beads as grinding media, with a ball-to-material ratio of 1:

3.

4. The method for preparing a black zirconia ceramic temperature probe handle according to claim 1, characterized in that, In step S5, the reducing atmosphere is hydrogen or a mixture of hydrogen and nitrogen.

5. The method for preparing a black zirconia ceramic temperature probe handle according to claim 1, characterized in that, In step S6, during coarse polishing, 95% alumina ceramic pillar with a diameter of 5mm and a length of 10mm and silicon carbide sand with a particle size of 40-100 mesh are added. During fine polishing, talc ceramic pillar with a diameter of 5mm and a length of 10mm, 320-mesh alumina micro powder, polishing liquid and brightener are added.

6. A handle for a black zirconia ceramic temperature probe, characterized in that, The handle is manufactured using the method described in any one of claims 1 to 5, and is a hollow, one-piece molded structure. Its connecting end is provided with internal thread.

7. The handle of a black zirconia ceramic temperature probe according to claim 6, characterized in that, The black zirconia ceramic has a single tetragonal phase structure, a blackness value of 110-200, a hardness of 14.6-15 GPa, and a fracture toughness of 12-13 MPa·m 1 / 2 , and does not shield electromagnetic signals because it does not contain a conductive component.

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