A method for preparing a low tcr low cost ceramic heating tube

Abstract

The application discloses a preparation method of a low-TCR low-cost ceramic heating tube, and comprises the following steps: (1) preparing an organic carrier: 60 parts by weight of terpineol, 20 parts by weight of ethyl cellulose, 10 parts by weight of a binder and 10 parts by weight of diethylene glycol acetate are placed into a magnetic stirrer and uniformly dissolved and mixed; (2) weighing metal powder: Mo: 50-70 parts by weight; Re: 20-30 parts by weight; Mn: 0-5 parts by weight; Cr: 10-15 parts by weight; by adopting Mo, Re, Mn and Cr in a specific ratio as the metal powder, the traditional mode of adopting metal ruthenium powder or a mixture of metal ruthenium powder and other common metal powder is replaced, the prices of Mo, Re, Mn and Cr are low, so that the preparation cost of the ceramic heating tube is effectively reduced, the purpose of low TCR is achieved, and the scale production is facilitated; meanwhile, the ceramic heating tube prepared by adopting the application has higher overall bending strength, and can better meet the use requirement.

Description

Technical Field

[0001] This invention relates to the field of ceramic heating elements, and in particular to a method for preparing a low-TCR, low-cost ceramic heating element. Background Technology

[0002] A ceramic heating element is a tubular heating element with a ceramic material as the tubular base, containing or coated with heating elements (such as resistance wires or conductive pastes), and converting electrical energy into heat energy through the Joule effect. Its core advantages are high temperature resistance, corrosion resistance, high thermal efficiency, and uniform heating. Furthermore, its tubular structure is suitable for insertion and surround heating applications, making it widely used in liquid heating, industrial furnaces, medical equipment, and other fields. It represents a specialized type of ceramic heating element with a "tubular shape" (distinguished from sheet-like or plate-like ceramic heating elements).

[0003] Current ceramic heating elements all have a resistive layer formed by sintering a slurry. In existing technologies, the metal powder used in this slurry is mostly ruthenium powder (Ru) or a mixture of ruthenium powder (Ru) and other common metal powders. While using ruthenium powder (Ru) can achieve a low TCR (transformation coefficient of thermal runaway), its high cost increases the manufacturing cost of ceramic heating elements, hindering large-scale production. Furthermore, the overall flexural strength of existing ceramic heating elements is relatively weak, failing to meet application requirements. Therefore, it is necessary to improve current ceramic heating elements. Summary of the Invention

[0004] In view of this, the present invention addresses the deficiencies of the existing technology, and its main objective is to provide a method for preparing a low-TCR, low-cost ceramic heating element, which can effectively solve the problems of high manufacturing cost and relatively weak flexural strength of existing ceramic heating elements.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a low-TCR, low-cost ceramic heating element includes the following steps:

[0007] (1) Preparation of organic carrier: 60 parts by weight of terpineol, 20 parts by weight of ethyl cellulose, 10 parts by weight of binder and 10 parts by weight of diethylene glycol acetate are placed in a magnetic stirrer and dissolved and mixed evenly.

[0008] (2) Weigh the metal powders: Mo: 50-70 parts by weight; Re: 20-30 parts by weight; Mn: 0-5 parts by weight; Cr: 10-15 parts by weight;

[0009] (3) Ball milling: Mix the metal powder with an organic carrier and place it in a ball milling jar containing zirconia ball milling beads for baking. After baking, place it in a planetary ball mill for ball milling to obtain a resistance slurry.

[0010] (4) The prepared resistive paste is printed onto an alumina substrate using a screen printing machine;

[0011] (5) The alumina substrate and the ceramic tubular sintered tube are pressed together by a hydraulic press using a transition layer to obtain a semi-finished product;

[0012] (6) The semi-finished product is sent into a high-temperature tunnel furnace to be sintered into ceramic, thereby producing a ceramic heating tube.

[0013] As a preferred embodiment, in step (1), the magnetic stirrer is used to dissolve and mix the raw materials of the organic carrier at 100°C.

[0014] As a preferred embodiment, the baking temperature inside the ball mill jar in step (3) is 120°C and the baking time is 2 hours.

[0015] As a preferred embodiment, the planetary ball mill in step (3) rotates at 350 Hz and the milling time is 4 hours.

[0016] As a preferred embodiment, the high-temperature tunnel furnace in step (6) is an atmosphere furnace with a furnace temperature of 1600℃.

[0017] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, as can be seen from the above technical solution:

[0018] By using a specific ratio of Mo, Re, Mn, and Cr as metal powders, the traditional method of using ruthenium powder or a mixture of ruthenium powder and other common metal powders is replaced. Mo, Re, Mn, and Cr are inexpensive, thereby effectively reducing the manufacturing cost of ceramic heating tubes and achieving low TCR, which facilitates large-scale mass production. At the same time, the ceramic heating tubes prepared using this invention have higher overall flexural strength, which can better meet the needs of use. Detailed Implementation

[0019] This invention discloses a method for preparing a low-TCR, low-cost ceramic heating element, comprising the following steps:

[0020] (1) Preparation of organic carrier: 60 parts by weight of terpineol, 20 parts by weight of ethyl cellulose, 10 parts by weight of binder and 10 parts by weight of diethylene glycol acetate were placed in a magnetic stirrer and dissolved and mixed evenly. The magnetic stirrer was used to dissolve and mix the raw materials of the organic carrier at 100°C.

[0021] (2) Weigh the metal powders: Mo: 50-70 parts by weight; Re: 20-30 parts by weight; Mn: 0-5 parts by weight; Cr: 10-15 parts by weight;

[0022] (3) Ball milling: The metal powder is mixed and placed in a ball milling jar containing zirconia grinding beads with an organic carrier and baked. After baking, it is placed in a planetary ball mill for ball milling to obtain a resistance slurry. The baking temperature in the ball milling jar is 120℃ and the baking time is 2 hours. The rotation speed of the planetary ball mill is 350 Hz and the ball milling time is 4 hours.

[0023] (4) The prepared resistive paste is printed onto the alumina substrate using a screen printing machine.

[0024] (5) A transition layer is used to press the alumina substrate and the ceramic tubular sintered tube together by a hydraulic press to obtain a semi-finished product.

[0025] (6) The semi-finished product is sent into a high-temperature tunnel furnace to be sintered into ceramic, thereby producing a ceramic heating tube. The high-temperature tunnel furnace is an atmosphere furnace with a furnace temperature of 1600℃.

[0026] The present invention will be further described in detail below with reference to several embodiments and comparative examples:

[0027] Example 1:

[0028] A method for preparing a low-TCR, low-cost ceramic heating element includes the following steps:

[0029] (1) Preparation of organic carrier: 60 parts by weight of terpineol, 20 parts by weight of ethyl cellulose, 10 parts by weight of binder and 10 parts by weight of diethylene glycol acetate were placed in a magnetic stirrer and dissolved and mixed evenly. The magnetic stirrer was used to dissolve and mix the raw materials of the organic carrier at 100°C.

[0030] (2) Weigh the metal powder: Mo: 50 parts by weight; Re: 30 parts by weight; Mn: 5 parts by weight; Cr: 15 parts by weight;

[0031] (3) Ball milling: The metal powder is mixed and placed in a ball milling jar containing zirconia grinding beads with an organic carrier and baked. After baking, it is placed in a planetary ball mill for ball milling to obtain a resistance slurry. The baking temperature in the ball milling jar is 120℃ and the baking time is 2 hours. The rotation speed of the planetary ball mill is 350 Hz and the ball milling time is 4 hours.

[0032] (4) The prepared resistive paste is printed onto the alumina substrate using a screen printing machine.

[0033] (5) A transition layer is used to press the alumina substrate and the ceramic tubular sintered tube together by a hydraulic press to obtain a semi-finished product.

[0034] (6) The semi-finished product is sent into a high-temperature tunnel furnace to be sintered into ceramic, thereby producing a ceramic heating tube. The high-temperature tunnel furnace is an atmosphere furnace with a furnace temperature of 1600℃.

[0035] Example 2:

[0036] A method for preparing a low-TCR, low-cost ceramic heating element includes the following steps:

[0037] (1) Preparation of organic carrier: 60 parts by weight of terpineol, 20 parts by weight of ethyl cellulose, 10 parts by weight of binder and 10 parts by weight of diethylene glycol acetate were placed in a magnetic stirrer and dissolved and mixed evenly. The magnetic stirrer was used to dissolve and mix the raw materials of the organic carrier at 100°C.

[0038] (2) Weigh the metal powder: Mo: 70 parts by weight; Re: 20 parts by weight; Mn: 0 parts by weight; Cr: 10 parts by weight;

[0039] (3) Ball milling: The metal powder is mixed and placed in a ball milling jar containing zirconia grinding beads with an organic carrier and baked. After baking, it is placed in a planetary ball mill for ball milling to obtain a resistance slurry. The baking temperature in the ball milling jar is 120℃ and the baking time is 2 hours. The rotation speed of the planetary ball mill is 350 Hz and the ball milling time is 4 hours.

[0040] (4) The prepared resistive paste is printed onto the alumina substrate using a screen printing machine.

[0041] (5) A transition layer is used to press the alumina substrate and the ceramic tubular sintered tube together by a hydraulic press to obtain a semi-finished product.

[0042] (6) The semi-finished product is sent into a high-temperature tunnel furnace to be sintered into ceramic, thereby producing a ceramic heating tube. The high-temperature tunnel furnace is an atmosphere furnace with a furnace temperature of 1600℃.

[0043] Example 3:

[0044] A method for preparing a low-TCR, low-cost ceramic heating element includes the following steps:

[0045] (1) Preparation of organic carrier: 60 parts by weight of terpineol, 20 parts by weight of ethyl cellulose, 10 parts by weight of binder and 10 parts by weight of diethylene glycol acetate were placed in a magnetic stirrer and dissolved and mixed evenly. The magnetic stirrer was used to dissolve and mix the raw materials of the organic carrier at 100°C.

[0046] (2) Weigh the metal powder: Mo: 56 parts by weight; Re: 30 parts by weight; Mn: 4 parts by weight; Cr: 10 parts by weight;

[0047] (3) Ball milling: The metal powder is mixed and placed in a ball milling jar containing zirconia grinding beads with an organic carrier and baked. After baking, it is placed in a planetary ball mill for ball milling to obtain a resistance slurry. The baking temperature in the ball milling jar is 120℃ and the baking time is 2 hours. The rotation speed of the planetary ball mill is 350 Hz and the ball milling time is 4 hours.

[0048] (4) The prepared resistive paste is printed onto the alumina substrate using a screen printing machine.

[0049] (5) A transition layer is used to press the alumina substrate and the ceramic tubular sintered tube together by a hydraulic press to obtain a semi-finished product.

[0050] (6) The semi-finished product is sent into a high-temperature tunnel furnace to be sintered into ceramic, thereby producing a ceramic heating tube. The high-temperature tunnel furnace is an atmosphere furnace with a furnace temperature of 1600℃.

[0051] Example 4:

[0052] A method for preparing a low-TCR, low-cost ceramic heating element includes the following steps:

[0053] (1) Preparation of organic carrier: 60 parts by weight of terpineol, 20 parts by weight of ethyl cellulose, 10 parts by weight of binder and 10 parts by weight of diethylene glycol acetate were placed in a magnetic stirrer and dissolved and mixed evenly. The magnetic stirrer was used to dissolve and mix the raw materials of the organic carrier at 100°C.

[0054] (2) Weigh the metal powder: Mo: 60 parts by weight; Re: 25 parts by weight; Mn: 5 parts by weight; Cr: 10 parts by weight;

[0055] (3) Ball milling: The metal powder is mixed and placed in a ball milling jar containing zirconia grinding beads with an organic carrier and baked. After baking, it is placed in a planetary ball mill for ball milling to obtain a resistance slurry. The baking temperature in the ball milling jar is 120℃ and the baking time is 2 hours. The rotation speed of the planetary ball mill is 350 Hz and the ball milling time is 4 hours.

[0056] (4) The prepared resistive paste is printed onto the alumina substrate using a screen printing machine.

[0057] (5) A transition layer is used to press the alumina substrate and the ceramic tubular sintered tube together by a hydraulic press to obtain a semi-finished product.

[0058] (6) The semi-finished product is sent into a high-temperature tunnel furnace to be sintered into ceramic, thereby producing a ceramic heating tube. The high-temperature tunnel furnace is an atmosphere furnace with a furnace temperature of 1600℃.

[0059] Example 5:

[0060] A method for preparing a low-TCR, low-cost ceramic heating element includes the following steps:

[0061] (1) Preparation of organic carrier: 60 parts by weight of terpineol, 20 parts by weight of ethyl cellulose, 10 parts by weight of binder and 10 parts by weight of diethylene glycol acetate were placed in a magnetic stirrer and dissolved and mixed evenly. The magnetic stirrer was used to dissolve and mix the raw materials of the organic carrier at 100°C.

[0062] (2) Weigh the metal powder: Mo: 60 parts by weight; Re: 22 parts by weight; Mn: 3 parts by weight; Cr: 15 parts by weight;

[0063] (3) Ball milling: The metal powder is mixed and placed in a ball milling jar containing zirconia grinding beads with an organic carrier and baked. After baking, it is placed in a planetary ball mill for ball milling to obtain a resistance slurry. The baking temperature in the ball milling jar is 120℃ and the baking time is 2 hours. The rotation speed of the planetary ball mill is 350 Hz and the ball milling time is 4 hours.

[0064] (4) The prepared resistive paste is printed onto the alumina substrate using a screen printing machine.

[0065] (5) A transition layer is used to press the alumina substrate and the ceramic tubular sintered tube together by a hydraulic press to obtain a semi-finished product.

[0066] (6) The semi-finished product is sent into a high-temperature tunnel furnace to be sintered into ceramic, thereby producing a ceramic heating tube. The high-temperature tunnel furnace is an atmosphere furnace with a furnace temperature of 1600℃.

[0067] Example 6:

[0068] A method for preparing a low-TCR, low-cost ceramic heating element includes the following steps:

[0069] (1) Preparation of organic carrier: 60 parts by weight of terpineol, 20 parts by weight of ethyl cellulose, 10 parts by weight of binder and 10 parts by weight of diethylene glycol acetate were placed in a magnetic stirrer and dissolved and mixed evenly. The magnetic stirrer was used to dissolve and mix the raw materials of the organic carrier at 100°C.

[0070] (2) Weigh the metal powder: Mo: 65 parts by weight; Re: 24 parts by weight; Mn: 1 part by weight; Cr: 10 parts by weight;

[0071] (3) Ball milling: The metal powder is mixed and placed in a ball milling jar containing zirconia grinding beads with an organic carrier and baked. After baking, it is placed in a planetary ball mill for ball milling to obtain a resistance slurry. The baking temperature in the ball milling jar is 120℃ and the baking time is 2 hours. The rotation speed of the planetary ball mill is 350 Hz and the ball milling time is 4 hours.

[0072] (4) The prepared resistive paste is printed onto the alumina substrate using a screen printing machine.

[0073] (5) A transition layer is used to press the alumina substrate and the ceramic tubular sintered tube together by a hydraulic press to obtain a semi-finished product.

[0074] (6) The semi-finished product is sent into a high-temperature tunnel furnace to be sintered into ceramic, thereby producing a ceramic heating tube. The high-temperature tunnel furnace is an atmosphere furnace with a furnace temperature of 1600℃.

[0075] Comparative Example 1:

[0076] The metal powder used is Ru only, and the remaining steps are the same as in Example 6.

[0077] The ceramic heating elements prepared in the above embodiments were then subjected to TCR (temperature coefficient of resistance) tests, flexural strength tests, and dry-burning tests. The TCR tests were conducted using a constant-temperature oil bath at temperatures ranging from 25℃ to 200℃; the flexural strength tests were performed using a flexural strength testing machine; and the dry-burning tests were performed using a dry-burning testing machine. The test results are as follows:

[0078] Table 1: Test results of TCR values ​​for each embodiment and comparative example

[0079] Example 1 47.65 48.55 49.88 51.05 52.28 53.31 54.55 55.72 963.24 Example 2 47.55 48.95 49.75 50.85 52.27 53.41 54.62 55.68 963.12 Example 3 47.40 48.75 49.85 51.08 52.31 53.37 54.58 55.71 964.41 Example 4 47.60 48.68 50.05 51.11 52.20 53.25 54.55 55.73 964.01 Example 5 47.50 48.77 49.65 51.24 52.15 53.42 54.58 55.46 963.41 Example 6 47.70 48.85 50.00 51.15 52.30 53.45 54.60 55.75 964.36 Comparative Example 1 47.00 48.13 49.26 50.39 51.52 52.65 53.78 54.91 961.70

[0080] As can be seen from the table above, the TCR value of the ceramic heating tube prepared by the present invention is comparable to that of Comparative Example 1, and both have achieved the effect of low TCR.

[0081] Table 2: Flexural strength results of each embodiment and comparative example

[0082]

[0083]

[0084] As can be seen from the table above, the ceramic heating tube prepared by the present invention has a much greater flexural strength than that of Comparative Example 1, and its flexural strength is better.

[0085] After dry burning tests, all embodiments and Comparative Example 1 showed uniform and stable heating.

[0086] The key design feature of this invention is that by using a specific ratio of Mo, Re, Mn, and Cr as metal powders, it replaces the traditional method of using ruthenium powder or a mixture of ruthenium powder and other common metal powders. Mo, Re, Mn, and Cr are inexpensive, thereby effectively reducing the manufacturing cost of ceramic heating elements and achieving a low TCR (Total Cr Content) for easy mass production. In addition, the ceramic heating elements prepared using this invention have higher overall flexural strength, which better meets the needs of use.

[0087] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a low-TCR, low-cost ceramic heating element, characterized in that: Includes the following steps: (1) Preparation of organic carrier: 60 parts by weight of terpineol, 20 parts by weight of ethyl cellulose, 10 parts by weight of binder and 10 parts by weight of diethylene glycol acetate are placed in a magnetic stirrer and dissolved and mixed evenly; (2) Weigh the metal powders: Mo: 50-70 parts by weight; Re: 20-30 parts by weight; Mn: 0-5 parts by weight; Cr: 10-15 parts by weight; (3) Ball milling: Mix the metal powder with the organic carrier and place it in a ball milling jar containing zirconia ball milling beads for baking. After baking, place it in a planetary ball mill for ball milling to obtain the resistance slurry. (4) The prepared resistive paste is printed onto the alumina substrate using a screen printing machine; (5) The alumina substrate and the ceramic tubular sintered tube are pressed together by a hydraulic press using a transition layer to obtain a semi-finished product; (6) The semi-finished product is sent into a high-temperature tunnel furnace to be sintered into ceramic, thereby producing a ceramic heating tube.

2. The method for preparing a low-TCR, low-cost ceramic heating element according to claim 1, characterized in that: In step (1), the magnetic stirrer is used to dissolve and mix the raw materials of the organic carrier at 100°C.

3. The method for preparing a low-TCR, low-cost ceramic heating element according to claim 1, characterized in that: In step (3), the baking temperature inside the ball mill jar is 120°C and the baking time is 2 hours.

4. The method for preparing a low-TCR, low-cost ceramic heating element according to claim 1, characterized in that: The ball milling time in step (3) is 4 hours.

5. The method for preparing a low-TCR, low-cost ceramic heating element according to claim 1, characterized in that: In step (6), the high-temperature tunnel furnace is an atmosphere furnace with a furnace temperature of 1600℃.

Images