Graphene ceramic electric cooker and preparation method thereof

Abstract

The present invention relates to the field of ceramics, and in particular to a graphene ceramic electric cooker and a preparation method thereof. The graphene ceramic electric cooker comprises a green body, which comprises a green body side wall and a green body bottom. An annular heat-conducting clip and an annular heat-insulating clip are provided inside the green body side wall, the annular heat-conducting clip is located inside the annular heat-insulating clip, a heat-conducting bottom plate is provided inside the green body bottom, and a graphene coating is provided on the bottom surface of the green body bottom. The present invention constructs an efficient multi-stage heat-conducting path formed by the graphene coating, the copper-based annular heat-conducting clip, and the heat-conducting bottom plate, which greatly improves the thermal conductivity coefficient and thus improves the heating speed; an annular heat-insulating clip made of porous ceramic material is provided inside the green body side wall, which reduces heat conduction between the green body and air, reduces heat loss, and reduces energy consumption.

Description

Technical Field

[0001] The present invention relates to the field of ceramics, and in particular to a graphene ceramic electric cooker and a preparation method thereof. Background Art

[0002] A ceramic electric rice cooker consists of a heating base and a ceramic pot body. The heating base converts electrical energy into heat through an electric heating element. The bottom surface of the ceramic pot body directly contacts the heating element of the heating base, transferring heat energy to the ceramic pot body, thereby cooking the food inside. Existing ceramic pot bodies have the following problems: the ceramic body has low thermal conductivity, resulting in slow heating; the ceramic sidewalls have poor thermal insulation, causing heat to be transferred from the sidewalls to the air, resulting in significant heat loss and increased energy consumption; and existing structures that use metal oxide coatings to improve thermal conductivity are prone to oxidation and failure during use, affecting long-term stability. In light of these issues, this case was initiated. Summary of the Invention

[0003] An object of the present invention is to solve at least the above problems through a graphene ceramic electric cooker and a preparation method thereof.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: the graphene ceramic electric cooker includes a blank, which includes a blank side wall and a blank bottom, and an annular heat-conducting clip and an annular heat-insulating clip are provided inside the blank side wall, and the annular heat-conducting clip is located inside the annular heat-insulating clip. A heat-conducting bottom sheet is provided inside the blank bottom, and the bottom surface of the blank bottom is provided with a graphene coating.

[0005] Preferably, the raw materials of the graphene coating include the following components in parts by weight: 8-14 parts of graphene, 15-17 parts of composite binder, 5-7 parts of antioxidant, 50-60 parts of solvent, and 3-5 parts of surfactant. The composite binder is composed of silica sol and aluminum sol in a weight ratio of 1:1, and the antioxidant is zinc oxide.

[0006] Preferably, the annular heat-conducting clip and the heat-conducting base are made of copper.

[0007] Preferably, the material of the annular thermal insulation clip is porous ceramic, and the raw materials of the porous ceramic include the following components in parts by weight: 50-70 parts of diatomaceous earth, 30-40 parts of kaolin, 10-12 parts of glass fiber, 5-7 parts of ammonium bicarbonate, 5-6 parts of quartz sand, and 2-3 parts of borax.

[0008] Preferably, the bottom of the blank bottom is provided with a downwardly protruding ring foot, and the graphene coating covers the bottom surface of the blank bottom within the ring foot.

[0009] Preferably, the outer surface of the side wall of the blank is covered with an artistic glaze, and the inner surface of the side wall and the top surface of the bottom of the blank are covered with a transparent glaze. The raw materials of the artistic glaze include the following components in parts by weight: 35-45 parts of quartz, 14-18 parts of potassium feldspar, 15-18 parts of kaolin, 8-12 parts of flake graphite, 1-2 parts of sodium humate, 0.5-1 part of titanium dioxide, 20-30 parts of borosilicate glass powder, 3-5 parts of zinc oxide, and 3-5 parts of nano alumina. The raw materials of the transparent glaze include the following components in parts by weight: 30-40 parts of quartz, 22-25 parts of potassium feldspar, 20-22 parts of kaolin, 20-30 parts of borosilicate glass powder, 3-5 parts of zinc oxide, and 3-5 parts of nano alumina.

[0010] A method for preparing a graphene ceramic electric cooker comprises the following steps:

[0011] Step a, forming the base and drying it;

[0012] Step b, preparing an annular heat-conducting clip, a heat-conducting bottom sheet and an annular heat-insulating clip, and placing the annular heat-conducting clip inside the annular heat-conducting clip;

[0013] Step c, placing the blank bottom on the bottom mold, placing the thermal conductive bottom sheet in the recess reserved on the blank bottom for positioning, then placing the annular thermal conductive clip and the annular thermal conductive clip assembly in the recess reserved on the blank bottom for positioning, with the thermal conductive bottom sheet located in the middle of the bottom of the annular thermal conductive clip, applying the blank at the connection and drying and fixing the annular thermal conductive clip, the thermal conductive bottom sheet and the annular thermal insulation clip;

[0014] Step d: placing an upper mold on the bottom mold, injecting the blank from the top, and vibrating the mold to remove bubbles. The slurry covers the annular heat-conducting clip, the heat-conducting bottom sheet, and the annular heat-insulating clip to form the side wall of the blank. After the slurry is dried and solidified, the mold is removed to form a blank, and the blank is trimmed and polished;

[0015] Step e: placing the green body into a kiln for biscuit firing;

[0016] Step f, forming a graphene coating on the inner bottom surface of the ring foot of the bisque-fired green body;

[0017] Step g, applying artistic glaze on the outer surface of the side wall of the blank and drying it, and applying transparent glaze on the inner surface of the side wall of the blank and the top surface of the bottom of the blank and drying it;

[0018] Step h: putting the graphene ceramic rice cooker into a kiln for glaze firing to obtain a graphene ceramic rice cooker.

[0019] Preferably, in step b, the preparation method of the annular thermal insulation clip is as follows: after mixing the various components of the raw materials, dry pressing is performed at a pressure of 15 MPa, and then segmented sintering is performed, first foaming at 600°C, and then keeping warm at 1100°C for 2 hours to form a closed-cell structure.

[0020] Preferably, in the step f, the preparation method of the graphene coating is as follows: prepare a graphene dispersion: weigh the raw materials of each component in proportion and set aside, mix the silica sol and aluminum sol in advance at a ratio of 1:1, add a surfactant to the solvent, stir at low speed for 40-60 minutes, add graphene in batches, stir at low speed for 30 minutes at room temperature to form a preliminary suspension, then transfer to an ultrasonic device and sonicate for 60-90 minutes; spray the graphene dispersion onto the bottom of the blank, the air pressure is 0.3-0.5MPa, the spraying distance is 20cm, multi-layer spraying is used, and low-temperature curing at 150-200°C for 1 hour is performed to form a dense coating, and then silica sol is sprayed on the graphene coating and cured at 300°C for 1 hour to form a protective layer.

[0021] Preferably, in step h, the glaze firing curve is as follows: from room temperature to 300°C within 1 hour, from 300°C to 600°C within 1.5 hours, from 600°C to 800°C within 1.5 hours, from 800°C to 900°C within 1 hour, keeping warm at 900°C for 2 hours, and finally cooling naturally, maintaining a reducing atmosphere in the temperature range of 800-900°C and before finally cooling to 200°C.

[0022] From the above description, it can be seen that the graphene ceramic electric cooker and the preparation method thereof provided by the present invention have the following beneficial effects: the present invention constructs an efficient multi-stage heat conduction path formed by the graphene coating, the copper-based annular heat-conducting clip, and the heat-conducting bottom plate, which greatly improves the thermal conductivity coefficient, thereby increasing the heating speed; an annular heat-insulating clip made of porous ceramic material is provided on the side wall of the green body, which reduces the heat conduction between the green body and the air, reduces heat loss, and reduces energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the structure of the graphene ceramic rice cooker. DETAILED DESCRIPTION

[0024] The present invention is further described below through specific embodiments.

[0025] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0026] like Figure 1As shown, the graphene ceramic electric cooker of the present invention includes a body, which includes a body side wall 1 and a body bottom 2. An annular heat-conducting clip 3 and an annular heat-insulating clip 4 are provided inside the body side wall 1. The annular heat-conducting clip 3 is located inside the annular heat-insulating clip 4. A heat-conducting bottom plate 5 is provided inside the body bottom 2, and a graphene coating 6 is provided on the bottom surface of the body bottom 2. The present invention constructs an efficient multi-stage heat conduction path formed by a graphene coating 6, a copper-based annular heat-conducting clip 3, and a heat-conducting bottom plate 5, which greatly improves the thermal conductivity coefficient and thus improves the heating speed. The graphene coating 6, the heat-conducting bottom plate 5 and the bottom 2 of the blank together constitute the bottom heat-conducting core, and the annular heat-conducting clip 3 helps to quickly conduct heat to various parts; the annular heat-conducting clip 3 is provided with an annular heat-insulating clip 4 made of porous ceramic material outside the annular heat-conducting clip 3, which reduces the heat conduction between the blank and the air, reduces heat loss, and reduces energy consumption. A control group is set to perform a heating speed test. The control group is fired with blank raw materials and glazes with the same formula components as those of the present invention, but without the annular heat-conducting clip 3, the annular heat-insulating clip 4, the heat-conducting bottom plate 5 and the graphene coating 6. After testing, the heating speed of the graphene ceramic electric cooker of the present invention is increased by 30-35% compared with the control group.

[0027] The raw materials of the graphene coating 6 include the following components in parts by weight: 8-14 parts of graphene, 15-17 parts of a composite binder, 5-7 parts of an antioxidant, 50-60 parts of a solvent, and 3-5 parts of a surfactant. The composite binder is prepared by silica sol and aluminum sol in a weight ratio of 1:1, and the antioxidant is zinc oxide. Graphene has an extremely high thermal conductivity and can conduct heat quickly. Graphene uses the best thermally conductive few-layer graphene with a purity of ≥98%. In the composite binder, the SiO2 particle size of the silica sol is 10-20 nm, the solid content is 30%, and the Al2O3 particle size of the aluminum sol is 5-10 nm, the solid content is 25%. The composite binder bonds graphene and ceramics at high temperatures. After sintering, the density of the silicon-aluminum composite binder is >95%, and the porosity is <3%, forming a dense layer, which increases the oxygen diffusion path length by more than 5 times and inhibits copper oxidation. ZnO reacts with O2 above 600°C to form a dense ZnO film, so the antioxidant forms a protective barrier at high temperatures and can also protect copper. Deionized water is used as the solvent to disperse the components and adjust the fluidity of the slurry. Sodium dodecylbenzene sulfonate is used as the surfactant to improve the dispersion of graphene and reduce agglomeration.

[0028] The annular heat-conducting clip 3 and the heat-conducting base plate 5 are made of copper. Copper has excellent thermal conductivity, and embedding it into the blank can significantly improve the thermal conductivity. The annular heat-conducting clip 3 is woven from thin copper strips, and the heat-conducting base plate 5 can be a solid copper sheet or woven from thin copper strips.

[0029] The annular thermal insulation clip 4 is made of porous ceramic. The raw materials of the porous ceramic include the following components by weight: 50-70 parts diatomaceous earth, 30-40 parts kaolin, 10-12 parts glass fiber, 5-7 parts ammonium bicarbonate, 5-6 parts quartz sand, and 2-3 parts borax. Among these components, diatomaceous earth, kaolin, and glass fiber serve as the base material, ammonium bicarbonate serves as the foaming agent, and quartz sand and borax serve as sintering aids. After calcination, a closed-pore porous ceramic is formed, with the pores filled with air and a porosity of 60-70%. Because the porous ceramic is divided into discontinuous small units by a large number of pores, heat cannot be quickly transferred through a continuous solid path, resulting in a low thermal conductivity and good thermal insulation performance.

[0030] The bottom of the base 2 is provided with a downwardly protruding ring foot 21, and the graphene coating 6 covers the bottom surface of the base 2 within the ring foot 21. The function of the ring foot 21 is to abut against the base plate during glaze firing, so that the bottom surface inside the ring foot 21 does not directly contact the base plate, preventing contact damage to the graphene coating 6. The relatively sealed environment formed between the ring foot 21 and the base plate also prevents high-temperature decomposition of the graphene coating 6. The heating part of the heating base that is matched with the graphene ceramic rice cooker is upwardly protruding, and the diameter of the heating part is slightly smaller than the inner diameter of the ring foot 21. During use, the heating part is embedded in the ring foot 21 and directly contacts the ceramic bottom surface. With the help of the graphene coating 6 and the thermal conductive bottom plate 5, heat is directly transferred through the ceramic bottom to the interior.

[0031] The outer surface of the side wall 1 of the blank is covered with an artistic glaze 7, and the inner surface of the side wall 1 and the top surface of the bottom 2 of the blank are covered with a transparent glaze 8. The raw materials of the artistic glaze 7 include the following components in parts by weight: 35-45 parts of quartz, 14-18 parts of potassium feldspar, 15-18 parts of kaolin, 8-12 parts of flake graphite, 1-2 parts of sodium humate, 0.5-1 part of titanium dioxide, 20-30 parts of borosilicate glass powder, 3-5 parts of zinc oxide, and 3-5 parts of nano alumina. The raw materials of the transparent glaze 8 include the following components in parts by weight: 30-40 parts of quartz, 22-25 parts of potassium feldspar, 20-22 parts of kaolin, 20-30 parts of borosilicate glass powder, 3-5 parts of zinc oxide, and 3-5 parts of nano alumina. Among the glaze components, graphite powder does not melt at high temperatures and retains its flaky structure, providing a silver-grey metallic luster or directional reflection effect, and ultimately forming metallic patterns on the glaze surface, giving Art Glaze 7 a unique glaze effect; borosilicate glass powder and zinc oxide can significantly reduce the firing temperature, nano-alumina can improve the mechanical strength of the glaze layer, and sodium humate can wrap carbon particles to prevent agglomeration; titanium dioxide can increase the glaze opacity and highlight the graphite luster.

[0032] The preparation method of the graphene ceramic electric cooker comprises the following steps:

[0033] Step a, forming the base 2 and drying it;

[0034] Step b, prepare an annular thermally conductive clip 3, a thermally conductive bottom sheet 5 and an annular thermal insulation clip 4, and place the annular thermally conductive clip 3 on the inner side of the annular thermally conductive clip 3; before assembly, first brush a layer of silica sol on the surface of the annular thermally conductive clip 3 and the thermally conductive bottom sheet 5 and dry them. After assembly, brush another layer of silica sol on the surface of the annular thermally conductive clip 3 and the thermally conductive bottom sheet 5 to play a role of fixing and protecting. The silica sol forms a protective layer on the copper surface during firing, isolating it from oxygen contact and preventing the copper from being oxidized during firing.

[0035] Step c, placing the blank bottom 2 on the bottom mold, placing the thermal conductive bottom sheet 5 in the recess reserved on the blank bottom 2 for positioning, then placing the annular thermal conductive clip 3 and the assembly of the annular thermal conductive clip 3 in the recess reserved on the blank bottom 2 for positioning, with the thermal conductive bottom sheet 5 located in the middle of the bottom of the annular thermal conductive clip 3, applying the blank at the connection and drying and fixing the annular thermal conductive clip 3, the thermal conductive bottom sheet 5 and the annular thermal insulation clip 4;

[0036] Step d, placing the upper mold on the bottom mold, injecting the blank from the top, and vibrating the mold to eliminate bubbles at the same time, the slurry covers the annular heat-conducting clip 3, the heat-conducting bottom sheet 5 and the annular thermal insulation clip 4 to form the blank side wall 1, and the slurry is demoulded after drying and solidification to form a blank, and the blank is repaired and polished; the upper mold has an inner core that can be embedded in the bottom mold, and a gap for the slurry to flow in is left between the bottom mold and the annular thermal insulation clip 4, and a gap for the slurry to flow in is left between the annular heat-conducting clip 3, the heat-conducting bottom sheet 5 and the inner core. The slurry is injected through the grouting port on the top of the upper mold so that the slurry covers the annular heat-conducting clip 3, the heat-conducting bottom sheet 5 and the annular thermal insulation clip 4. After the blank is dried, the blank is demoulded, and the blank is repaired and polished to obtain a blank with the annular heat-conducting clip 3, the heat-conducting bottom sheet 5 and the annular thermal insulation clip 4 embedded therein.

[0037] Step e: placing the green body into a kiln for biscuit firing;

[0038] Step f, forming a graphene coating 6 on the inner bottom surface of the ring foot 21 of the bisque-fired green body;

[0039] Step g, applying an artistic glaze 7 on the outer surface of the side wall 1 of the blank and drying it, and applying a transparent glaze 8 on the inner surface of the side wall 1 and the top surface of the bottom 2 of the blank and drying it;

[0040] Step h: putting the graphene ceramic rice cooker into a kiln for glaze firing to obtain a graphene ceramic rice cooker.

[0041] In step b, the preparation method of the annular thermal insulation clip 4 is as follows: after mixing the various components of the raw materials, dry pressing is performed at a pressure of 15 MPa, and then segmented sintering is performed, first foaming at 600°C, and then keeping warm at 1100°C for 2 hours to form a closed-cell structure.

[0042] In step f, the graphene coating 6 is prepared as follows: a graphene dispersion is prepared and sprayed onto the base 2 at an air pressure of 0.3-0.5 MPa and a spraying distance of 20 cm using multiple layers of spraying. The coating is then cured at a low temperature of 150-200°C for 1 hour to form a dense coating. Silica sol is then sprayed onto the graphene coating 6 and cured at 300°C for 1 hour to form a protective layer. The silica sol forms a protective film on the surface of the graphene coating 6, blocking oxygen permeation. Since the artistic glaze 7 and the sealing glaze are low-temperature glazes fired at 900°C, low-temperature firing effectively prevents damage to the graphene coating 6 during firing.

[0043] In step h, the glaze firing curve is as follows: from room temperature to 300°C in 1 hour, from 300°C to 600°C in 1.5 hours, from 600°C to 800°C in 1.5 hours, from 800°C to 900°C in 1 hour, kept at 900°C for 2 hours, and finally cooled naturally, maintaining a reducing atmosphere in the temperature range of 800-900°C and before finally cooling to 200°C. Regarding the protection of copper and graphene coating 6 during the glaze firing process, since the oxidation rate is fastest below 600-800°C, the temperature needs to be raised quickly in the low-temperature stage to reduce the residence time of the copper wire in the oxidizing atmosphere and avoid decomposition and damage of the graphene coating 6; in the high-temperature stage, the reducing atmosphere is ensured to be stable to avoid oxygen back in the middle and protect the copper wire and graphene coating 6. The glaze firing temperature is 900°C; in the cooling stage, the reducing atmosphere is maintained until the temperature drops below 200°C to prevent the copper from being oxidized again during the cooling process; regarding the glaze firing of artistic glaze 7: since flake graphite does not melt at high temperatures and is protected by a reducing atmosphere, it can retain its flaky structure, provide a silver-gray metallic luster or directional reflection effect, and have a unique artistic effect.

[0044] The above are only some specific implementation methods of the present invention, but the design concept of the present invention is not limited to this. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. Graphene ceramic rice cooker, characterized by: The invention comprises a blank, wherein the blank comprises a blank side wall and a blank bottom, wherein an annular heat-conducting clip and an annular heat-insulating clip are arranged inside the blank side wall, wherein the annular heat-conducting clip is located inside the annular heat-insulating clip, wherein a heat-conducting bottom plate is arranged inside the blank bottom, and wherein the bottom surface of the blank bottom is provided with a graphene coating, wherein the raw materials of the graphene coating comprise the following components in parts by weight: 8-14 parts of graphene, 15-17 parts of a composite binder, 5-7 parts of an antioxidant, 50-60 parts of a solvent, and 3-5 parts of a surfactant, wherein the composite binder is configured by silica sol and aluminum sol in a weight ratio of 1:1, wherein the antioxidant is zinc oxide, and the material of the annular heat-insulating clip is porous ceramic, and the raw materials of the porous ceramic comprise the following components in parts by weight: 50-70 parts of diatomaceous earth, 30-40 parts of kaolin, and glass fiber. 10-12 parts, 5-7 parts of ammonium bicarbonate, 5-6 parts of quartz sand, and 2-3 parts of borax; the outer surface of the side wall of the body is covered with artistic glaze, and the inner surface of the side wall and the top surface of the body bottom are covered with transparent glaze. The raw materials of the artistic glaze include the following components in parts by weight: 35-45 parts of quartz, 14-18 parts of potassium feldspar, 15-18 parts of kaolin, 8-12 parts of flake graphite, 1-2 parts of sodium humate, 0.5-1 part of titanium dioxide, 20-30 parts of borosilicate glass powder, 3-5 parts of zinc oxide, and 3-5 parts of nano-alumina. The raw materials of the transparent glaze include the following components in parts by weight: 30-40 parts of quartz, 22-25 parts of potassium feldspar, 20-22 parts of kaolin, 20-30 parts of borosilicate glass powder, 3-5 parts of zinc oxide, and 3-5 parts of nano-alumina.

2. The graphene ceramic rice cooker according to claim 1, characterized in that: The annular heat-conducting clip and the heat-conducting base are made of copper.

3. The graphene ceramic rice cooker according to claim 1, characterized in that: The bottom of the blank bottom is provided with a downwardly protruding ring foot, and the graphene coating covers the bottom surface of the blank bottom within the ring foot.

4. The method for preparing a graphene ceramic electric cooker according to any one of claims 1 to 3, characterized in that: The steps include: Step a, forming and drying the base; Step b, preparing an annular heat-conducting clip, a heat-conducting bottom sheet and an annular heat-insulating clip, and placing the annular heat-conducting clip inside the annular heat-conducting clip; Step c, placing the blank bottom on the bottom mold, placing the thermal conductive bottom sheet in the recess reserved on the blank bottom for positioning, then placing the annular thermal conductive clip and the annular thermal conductive clip assembly in the recess reserved on the blank bottom for positioning, with the thermal conductive bottom sheet located in the middle of the bottom of the annular thermal conductive clip, applying the blank at the connection and drying and fixing the annular thermal conductive clip, the thermal conductive bottom sheet and the annular thermal insulation clip; Step d: placing an upper mold on the bottom mold, injecting the blank from the top, and vibrating the mold to remove bubbles. The slurry covers the annular heat-conducting clip, the heat-conducting bottom sheet, and the annular heat-insulating clip to form the side wall of the blank. After the slurry is dried and solidified, the mold is removed to form a blank, and the blank is trimmed and polished; Step e: placing the green body into a kiln for biscuit firing; Step f, forming a graphene coating on the inner bottom surface of the ring foot of the bisque-fired green body; Step g, applying artistic glaze on the outer surface of the side wall of the blank and drying it, and applying transparent glaze on the inner surface of the side wall of the blank and the top surface of the bottom of the blank and drying it; Step h: putting the graphene ceramic rice cooker into a kiln for glaze firing to obtain a graphene ceramic rice cooker.

5. The method for preparing a graphene ceramic electric cooker according to claim 4, wherein: In step b, the preparation method of the annular thermal insulation clip is as follows: after mixing the various components of the raw materials, dry pressing is performed at a pressure of 15 MPa, and then segmented sintering is performed, first foaming at 600°C, and then keeping warm at 1100°C for 2 hours to form a closed-cell structure.

6. The method for preparing a graphene ceramic electric cooker according to claim 4, wherein: In the step f, the graphene coating is prepared as follows: a graphene dispersion is prepared, and the graphene dispersion is sprayed onto the bottom of the blank at an air pressure of 0.3-0.5 MPa and a spraying distance of 20 cm. Multi-layer spraying is adopted, and low-temperature curing is performed at 150-200° C. for 1 hour to form a dense coating. Then, silica sol is sprayed on the graphene coating and cured at 300° C. for 1 hour to form a protective layer.

7. The method for preparing a graphene ceramic electric cooker according to claim 4, wherein: In step h, the glaze firing curve is as follows: from room temperature to 300°C within 1 hour, from 300°C to 600°C within 1.5 hours, from 600°C to 800°C within 1.5 hours, from 800°C to 900°C within 1 hour, keeping at 900°C for 2 hours, and finally cooling naturally, maintaining a reducing atmosphere in the temperature range of 800-900°C and before finally cooling to 200°C.

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