A foam PTC ceramic heating element and its manufacturing method

Abstract

This invention relates to the field of PTC ceramic technology, specifically to a foam PTC ceramic heating element and its manufacturing method. The element includes a foam ceramic substrate with two opposing front surfaces, each with a dense ceramic layer. An electrode layer is disposed on the surface of the dense ceramic layer. Specifically, a foam ceramic slurry is first prepared, then sprayed onto a foam sponge. Spraying is stopped when slurry overflows, and the substrate is dried. This process is repeated 2-4 times to obtain the foam ceramic substrate. A dense ceramic paste is then prepared, and the front surfaces of the foam ceramic substrate are immersed to a certain depth in the paste. After a period of time, surface residue is scraped off, and the substrate is dried. The resulting foam PTC ceramic preform is sintered, dimensionally trimmed, coated with electrodes, and then infiltrated to obtain the foam PTC ceramic heating element. The foam PTC ceramic heating element of this invention has a simple structure and is easy to manufacture.

Description

Technical Field

[0001] This invention relates to the field of PTC ceramic technology, specifically to a foamed PTC ceramic heating element and its manufacturing method. Background Technology

[0002] PTC thermistor ceramics are widely used in heating elements of household and automotive air conditioning systems due to their self-regulating temperature characteristics. Traditional dense bulk PTC ceramics have a thermal conductivity of 1.5-2 W / mK, making them poor heat conductors. Since the heat generated by PTC ceramic elements is conducted from the inside out, traditional dense bulk PTC ceramics require heat sinks for heat dissipation. Due to their poor thermal conductivity, increasing power by reducing thickness often requires consideration of the ceramic sheet's pressure resistance. Honeycomb PTC ceramics can have a larger heat exchange area, but large-scale honeycomb ceramic fabrication is very difficult. Summary of the Invention

[0003] The purpose of this invention is to provide a foam PTC ceramic heating element and its manufacturing method, which can at least solve some of the defects in the prior art.

[0004] To achieve the above objectives, the technical solution of the present invention is a foam PTC ceramic heating element, comprising a foam ceramic substrate, wherein the foam ceramic substrate has two oppositely arranged front surfaces, and a dense ceramic layer is disposed on each of the two front surfaces, and an electrode layer is disposed on the surface of the dense ceramic layer.

[0005] Furthermore, the foam ceramic matrix includes a foam sponge and a foam ceramic slurry filled within the foam sponge.

[0006] Furthermore, the porosity (PPI) of the foam sponge is 5-20.

[0007] Furthermore, the foam sponge is in the shape of a cuboid, cylinder, trapezoidal column, or prism.

[0008] Furthermore, the thickness of the dense ceramic layer is 0.5-3 mm.

[0009] Furthermore, the thickness of the electrode layer is 10-30 μm.

[0010] The present invention also provides a method for manufacturing the above-mentioned foam PTC ceramic heating element, comprising the following steps:

[0011] S1. Preparation of foam ceramic slurry;

[0012] S2. Spray the foam ceramic slurry onto the foam sponge. Stop spraying when the slurry overflows and let it dry.

[0013] S3. Repeat step S2 2-4 times to obtain the foam ceramic matrix;

[0014] S4. Prepare a dense ceramic paste;

[0015] S5. Immerse the front surface of the foam ceramic substrate obtained in step S3 into the dense ceramic paste to a certain depth, keep it for a period of time, scrape off the surface residue, dry it, and form a dense ceramic layer on the front surface of the foam ceramic substrate to obtain a foam PTC ceramic blank.

[0016] S6. Sinter the foamed PTC ceramic preform to obtain foamed PTC ceramic parts;

[0017] S7. After trimming the dimensions of the foam PTC ceramic part, cleaning and drying it, electrodes are applied to the dense ceramic layer and then sintered to obtain the foam PTC ceramic heating element.

[0018] Further, step S1 specifically involves adding 30 parts of deionized water, 15 parts of 10% PVA solution, 0.3 parts of dispersant, and 0.15 parts of defoamer to 100 parts of prepared ceramic powder and then ball milling the mixture. Once ball milling is complete, foamed ceramic slurry can be obtained.

[0019] Further, step S4 specifically involves adding 15 parts of deionized water, 15 parts of 10% PVA solution, 0.3 parts of dispersant, and 0.15 parts of defoamer to 100 parts of prepared ceramic powder and then ball milling it. Once ball milling is complete, a dense ceramic paste can be obtained.

[0020] Further, step S6 specifically involves: heating the foamed PTC ceramic preform to 1200-1400℃ at a rate of 0.5-1℃ / min and holding it at that temperature for 10-60 minutes; after holding, cooling it to 1000℃ at a rate of 5-8℃ / min, followed by furnace cooling to obtain the foamed PTC ceramic part. Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The present invention fabricates a PTC ceramic heating element by sequentially setting a dense ceramic layer and an electrode layer on the two large surfaces of a lightweight foam ceramic matrix. This not only improves heat dissipation performance but also significantly reduces the weight of the PTC ceramic heating element, with a density reaching 1 g / cm³. 3 the following;

[0022] (2) The present invention prepares a foam ceramic matrix by repeatedly spraying foam ceramic slurry onto a foam sponge and drying it. The foam ceramic slurry can enter the pores inside the foam sponge through the pores on the surface of the foam sponge, which not only meets the performance requirements of the PTC ceramic heating element, but also makes the PTC ceramic heating element lighter.

[0023] (3) The preparation method of the present invention is simple and easy to implement. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the structure of the foam PTC ceramic heating element provided in an embodiment of the present invention;

[0026] Figure 2 A magnified test image of the foam ceramic matrix provided in an embodiment of the present invention;

[0027] In the figure: 1. Foam ceramic matrix; 2. Dense ceramic layer; 3. Electrode layer. Detailed Implementation

[0028] 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.

[0029] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0030] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0031] Example 1

[0032] like Figure 1As shown, this embodiment provides a foam PTC ceramic heating element, including a foam ceramic substrate 1. The foam ceramic substrate 1 has two opposing front surfaces, each with a dense ceramic layer 2. An electrode layer 3 is disposed on the surface of the dense ceramic layer 2. This embodiment, by sequentially distributing the dense ceramic layer 2 and the electrode layer 3 on the two front surfaces of the lightweight foam ceramic substrate 1, not only obtains a PTC ceramic heating element with better heat dissipation performance but also significantly reduces the weight of the PTC ceramic heating element, achieving a density of 1 g / cm³. 3 the following.

[0033] Furthermore, the foam ceramic matrix 1 includes a foam sponge and a foam ceramic slurry filled within the foam sponge. For example... Figure 2 As shown, the foam sponge has a three-dimensional network structure with abundant porosity, and the porosity is filled with foam ceramic slurry. Optimally, the foam sponge can be made of polyurethane foam, which is lightweight, has good load-bearing capacity, and high porosity. Furthermore, the porosity (PPI) of the foam sponge is 5-20.

[0034] Furthermore, the shape of the foam sponge can be designed as needed, and can be a cuboid, cylinder, trapezoidal column, or prism.

[0035] Furthermore, the thickness of the dense ceramic layer 2 is 0.5-3 mm.

[0036] Furthermore, the thickness of the electrode layer 3 is 10-30 μm.

[0037] Example 2

[0038] This embodiment provides a method for manufacturing a foam PTC ceramic heating element as described in Embodiment 1, comprising the following steps:

[0039] S1. Preparation of foam ceramic slurry;

[0040] S2. Spray the foam ceramic slurry onto the foam sponge. Stop spraying when the slurry overflows and let it dry.

[0041] S3. Repeat step S2 2-4 times to obtain foam ceramic matrix 1;

[0042] S4. Prepare a dense ceramic paste;

[0043] S5. Immerse the front surface of the foam ceramic substrate 1 obtained in step S3 into the dense ceramic paste for 0.5-3mm, keep it for a period of time to form a dense ceramic layer 2 on the front surface of the foam ceramic substrate 1, scrape off the residual paste on the surface with a tool, dry it, and obtain the foam PTC ceramic blank.

[0044] S6. Sinter the foamed PTC ceramic preform to obtain foamed PTC ceramic parts;

[0045] S7. After trimming the dimensions of the foam PTC ceramic part, cleaning and drying it, electrodes are applied to the dense ceramic layer 2 and then sintered to obtain the foam PTC ceramic heating element.

[0046] This embodiment involves repeatedly spraying foam ceramic slurry onto a foam sponge and drying it, spraying until slurry overflows each time. This allows a significant amount of foam ceramic slurry to be embedded into the voids within the foam sponge, ensuring that the fabricated foam ceramic substrate 1 meets the performance requirements of the PTC ceramic heating element. Furthermore, the PTC ceramic heating element prepared using this foam ceramic substrate 1 and the method of this embodiment can achieve a density of 1 g / cm³. 3 the following.

[0047] Further, step S1 specifically involves adding 30g of deionized water, 15g of 10% PVA (polyvinyl alcohol) solution, 0.3g of dispersant, and 0.15g of defoamer to 100g of prepared ceramic powder and then ball milling it. Once ball milling is complete, foamed ceramic slurry can be obtained.

[0048] Further, step S4 specifically involves adding 15g of deionized water, 15g of 10% PVA solution, 0.3g of dispersant, and 0.15g of defoamer to 100g of prepared ceramic powder and then ball milling it. Once ball milling is complete, a dense ceramic paste can be obtained.

[0049] In the above-mentioned foamed ceramic slurry and dense ceramic paste, the ceramic powder can be PTC ceramic powder commonly used in the field, the main components of which include BaTiO3, PbTiO3, CaTiO3, etc.; the dispersant can be a commonly used dispersant in the field, such as polyammonium methacrylate, ammonium polyacrylate, etc.; and the defoamer can be a commonly used defoamer in the field, such as n-octanol, n-butanol, etc.

[0050] Further, step S6 specifically involves: heating the foamed PTC ceramic preform to 1200-1400℃ at a rate of 0.5-1℃ / min and holding it at that temperature for 10-60 minutes; after holding, cooling it to 1000℃ at a rate of 5-8℃ / min; and then cooling it in the furnace to obtain the foamed PTC ceramic part.

[0051] Further, step S7 specifically involves: trimming the length, width, and thickness of the foam PTC ceramic part; cleaning and drying the trimmed foam PTC ceramic part; printing electrode paste on the dense ceramic layer 2; and then firing at 550-600℃ to form an electrode layer 3 on the surface of the dense ceramic layer 2, thereby obtaining the foam PTC ceramic heating element.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing a foam PTC ceramic heating element, characterized in that, The foam PTC ceramic heating element includes a foam ceramic matrix, which has two opposing front surfaces. A dense ceramic layer is disposed on each of the two front surfaces, and an electrode layer is disposed on the surface of the dense ceramic layer. The foam ceramic matrix includes a foam sponge and a foam ceramic slurry filled within the foam sponge. The manufacturing method includes the following steps: S1. Preparation of foam ceramic slurry; S2. Spray the foam ceramic slurry onto the foam sponge. Stop spraying when the slurry overflows and let it dry. S3. Repeat step S2 2-4 times to obtain the foam ceramic matrix; S4. Prepare a dense ceramic paste; S5. Immerse the front surface of the foam ceramic substrate obtained in step S3 into the dense ceramic paste to a certain depth, keep it for a period of time, scrape off the surface residue, dry it, and form a dense ceramic layer on the front surface of the foam ceramic substrate to obtain a foam PTC ceramic blank. S6. Sinter the foamed PTC ceramic preform to obtain foamed PTC ceramic parts; S7. After trimming the dimensions of the foam PTC ceramic part, cleaning and drying it, electrodes are applied to the dense ceramic layer and then sintered to obtain the foam PTC ceramic heating element.

2. The manufacturing method as described in claim 1, characterized in that, Step S1 is as follows: Add 30 parts of deionized water, 15 parts of 10% PVA solution, 0.3 parts of dispersant and 0.15 parts of defoamer to 100 parts of prepared ceramic powder and ball mill. After ball milling, foam ceramic slurry can be obtained.

3. The manufacturing method as described in claim 1, characterized in that, Step S4 is as follows: Add 15 parts of deionized water, 15 parts of 10% PVA solution, 0.3 parts of dispersant and 0.15 parts of defoamer to 100 parts of prepared ceramic powder and ball mill. After ball milling, a dense ceramic paste can be obtained.

4. The manufacturing method as described in claim 1, characterized in that, Step S6 specifically involves heating the foamed PTC ceramic preform to 1200-1400℃ at a rate of 0.5-1℃ / min and holding it at that temperature for 10-60 minutes. After holding, the temperature is lowered to 1000℃ at a rate of 5-8℃ / min, and then cooled in the furnace to obtain the foamed PTC ceramic part.

5. The manufacturing method as described in claim 1, characterized in that: The porosity (PPI) of the foam sponge is 5-20.

6. The manufacturing method as described in claim 1, characterized in that: The foam sponge is in the shape of a cuboid, cylinder, trapezoidal column, or prism.

7. The manufacturing method as described in claim 1, characterized in that: The thickness of the dense ceramic layer is 0.5-3 mm.

8. The manufacturing method as described in claim 1, characterized in that: The thickness of the electrode layer is 10-30 μm.

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