Temperature-sensitive medium material for flame detector and preparation method thereof

Abstract

A temperature-sensitive medium material for a flame detector, the weight parts of each component in the temperature-sensitive medium material being BPT ferroelectric material 8-9.5 parts, BPT FeCr ferroelectric material 8-9.5 parts, MCT semiconductor ceramic material 15-19 parts, Fe2O3 7.5-8.5 parts, MnCO3 6.5-7.5 parts, Cr2O3 0.5-1 part, NaCl 2.3-3.5 parts, Ni2O3 1.5-2.5 parts, Al2O3 42-50.7 parts.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flame detectors, in particular to a temperature-sensitive medium material for a flame detector and a preparation method thereof. BACKGROUND

[0002] In some special occasions, such as the closed engine compartment of special vehicles (high-end passenger cars, VIP cars, internal combustion engine cars, special vehicles, etc.), due to the long-term work of the engine, the high temperature is easy to ignite the oil seepage and leakage in the compartment, causing a fire. In order to ensure the safety of such equipment, it is necessary to install a protection system with high-performance flame detectors. In the photovoltaic industry of the new energy industry, due to the defects of the polycrystalline silicon ingot furnace itself, unreasonable loading, and unreasonable heating parameter setting, the crucible containing silicon material breaks during heating or cooling, causing silicon liquid overflow. If the silicon liquid overflow is not discovered in time, the overflowed silicon liquid will accumulate a lot over time, which may melt through the furnace bottom, and if it encounters a water cooling pipeline, water vapor will easily accumulate and cause a safety accident. The air preheater is an important heat exchange equipment of the thermal power generating unit. The unburned components deposit on the heating surface, which is easy to produce hot spots. If the hot spot is not discovered in time, it may cause a fire. Open-air coal piles have many disadvantages such as dust, sewage, loss, and coal quality degradation. The state requires that all coal-using units will gradually use coal storage warehouses. The oxidation and spontaneous combustion of coal in the storage warehouse must be monitored at all times. If the refractory material lining of a high-temperature and high-pressure boiler (pipe) falls off, the high-temperature and high-pressure directly act on the metal of the furnace shell (pipe wall), which may reduce the heat resistance of the metal and cause an explosion.

[0003] The commonly used sensors at present mainly include a wire type temperature sensor, a hot-wire type temperature sensor, and an original double-parameter wire type flame detector. These sensors have the following problems:

[0004] 1. Wire type temperature sensor

[0005] The distributed optical fiber measures the average temperature of the distribution area, but its resolution is low, the temperature sensing area is too large, and the measurement error is large.

[0006] The general optical fiber is protected by organic materials, and the use temperature is low. If gold optical fiber or armored protection is used, the cost is high, and it is difficult to bear the cost in ordinary application or large quantities.

[0007] 2. Hot-wire type temperature sensor

[0008] The hot-wire type temperature sensor is used in relatively static devices such as coal gasification furnaces, coal storage warehouses, and air preheaters. There is no report on its application in a vibrating environment.

[0009] 3. Equipped with a dual-parameter linear flame detector

[0010] The original dual-parameter linear flame detector has the function of jointly determining the fire alarm using two temperature characteristic parameters, resistance and capacitance. It has the advantages of strong environmental adaptability and high reliability, but the capacitance change factor C... 500℃ / C 25℃ The sensitivity is around 60, which is relatively low and not conducive to accurate fire alarm detection. The capacitance change factor C of the original dual-parameter linear flame detector... 500℃ / C 25℃ The test data is shown in the table below:

[0011]

[0012] As a new type of industrial sensor, flame detectors are used in many applications involving personal and property safety. They are an extremely important new member of the sensor family and have broad application prospects. Using high-performance flame detectors is a convenient, reliable, and relatively inexpensive method. Among them, the composition design and preparation method of the temperature-sensitive medium material used in flame detectors are particularly critical. Summary of the Invention

[0013] The purpose of this invention is to address the shortcomings of existing technologies by providing a temperature-sensitive dielectric material for flame detectors and its preparation method. A dual-parameter linear flame detector made from this temperature-sensitive dielectric material possesses highly sensitive temperature-dependent resistance and capacitance parameters, enabling reliable fire detection. Furthermore, it is adaptable to environmentally friendly applications such as impact, vibration, and humidity.

[0014] The objective of this invention is achieved by the following scheme: a temperature-sensitive dielectric material for a flame detector, wherein the weight parts of each component in the temperature-sensitive dielectric material are as follows: 8-9.5 parts of BPT ferroelectric material, 8-9.5 parts of BPTFeCr ferroelectric material, 15-19 parts of MCT semiconductor ceramic material, 7.5-8.5 parts of Fe2O3, 6.5-7.5 parts of MnCO3, 0.5-1 part of Cr2O3, 2.3-3.5 parts of NaCl, 1.5-2.5 parts of Ni2O3, and 42-50.7 parts of Al2O3.

[0015] The weight parts of each component in the BPT ferroelectric material are: BaO 8-10 parts, TiO2 30-40 parts, and Pb3O4 50-62 parts.

[0016] The weight parts of each component in the BPTFeCr ferroelectric material are as follows: BaO 8-10 parts, TiO2 29-34 parts, Pb3O4 49-54 parts, Fe2O3 1-2 parts, and Cr2O3 7-9 parts.

[0017] The weight parts of each component in the MCT semiconductor ceramic material are: 70-75 parts Cr2O3, 24-28 parts MgO, and 1-3 parts TiO2.

[0018] The preparation method of the temperature-sensitive dielectric material for flame detectors includes the following steps:

[0019] 1) Preparation of BPT ferroelectric materials;

[0020] 1-1) Ingredients: Take each component according to the proportions described in BPT ferroelectric materials, add anhydrous ethanol, stir and mix, and dry;

[0021] 1-2) Pre-calcination: The powder obtained in step 1-1) is pre-calcined at 1000-1100℃ for 1.5-2.5 hours, cooled to room temperature, and then ball-milled into powder.

[0022] 1-3) Sintering: The powder obtained by pre-sintering is sintered at 1200-1300℃ for 1.5-2.5 hours, cooled to room temperature and then taken out and ball-milled into powder to obtain BPT ferroelectric material;

[0023] 2) Preparation of BPTFeCr ferroelectric materials;

[0024] 2-1) Ingredients: Take each component according to the proportions described for BPTFeCr ferroelectric materials, add anhydrous ethanol, stir and mix, and dry;

[0025] 2-2) Pre-calcination: The powder obtained in step 2-1) is pre-calcined at 1000-1100℃ for 1.5-2.5 hours, cooled to room temperature, and then ball-milled into powder.

[0026] 2-3) Sintering: The powder obtained by pre-calcination is sintered at 1200-1300℃ for 1.5-2.5 hours, cooled to room temperature, and then ball-milled into powder to obtain BPTFeCr ferroelectric material.

[0027] 3) Preparation of MCT semiconductor ceramic materials;

[0028] 3-1) Ingredients: Take each component according to the proportions described in the MCT semiconductor ceramic material, add anhydrous ethanol, stir and mix, and dry;

[0029] 3-2) Pre-calcination: The powder obtained in step 3-1) is pre-calcined at 1000-1100℃ for 1.5-2.5 hours, cooled to room temperature, and then ball-milled into powder.

[0030] 3-3) Sintering: The powder obtained by pre-sintering is sintered at 1250-1350℃ for 1.5-2.5 hours, cooled to room temperature, taken out, and ball-milled into powder to obtain MCT semiconductor ceramic material;

[0031] 4) Ingredients: Take each component according to the proportions described in claim 1, place them in an agate jar, add anhydrous ethanol, stir and mix at high speed, and dry for later use;

[0032] 5) Sintering: The powder prepared in step 4) is sintered at 1250℃~1300℃ for 45 hours, cooled to room temperature and then taken out and ball-milled into powder to obtain the temperature-sensitive medium material.

[0033] During the preparation process, powder is loaded into a corundum crucible and sintered in a high-temperature sintering furnace.

[0034] Application of temperature-sensitive dielectric materials for flame detectors in the fabrication of temperature-sensitive cables for flame detectors.

[0035] BPT ferroelectric materials and BPTFeCr ferroelectric materials are used to form the temperature-sensitive component of dielectric materials. Exceeding their upper limit will excessively reduce the initial resistance and temperature coefficient of resistance of the temperature-sensitive dielectric material, while falling below the lower limit will prevent them from effectively functioning as the temperature-sensitive component. MCT semiconductor ceramic materials, Fe2O3, MnCO3, Cr2O3, Ni2O3, and Al2O3 are temperature-sensitive components of dielectric materials. The upper and lower limits are set because these components have suitable resistance values ​​and suitable NTC temperature coefficients within their respective ranges. NaCl is an additive for dielectric materials, which can further improve the temperature change rate of resistance and capacitance, thereby further improving sensitivity. Its upper and lower limits are also set because it has suitable NTC temperature coefficients and capacitance temperature coefficients within its respective range.

[0036] The advantages of this invention are: 1. The material of this invention has sensitive temperature characteristics of resistance and capacitance, wherein the change factor C of the temperature characteristic of capacitance is... 500℃ / C 25℃ Reaching 250 or above;

[0037] 2. The material of this invention is a microstructure-stable powder material formed by high-temperature sintering. Therefore, it has good vibration and impact resistance, good environmental adaptability, and can work in environments with frequent vibrations, such as tracked vehicles.

[0038] 3. The temperature-sensitive dielectric material produced by this invention has a wide range of applications. All materials can be used within 900℃. The Φ2mm dual-parameter temperature-sensitive cable produced has a room temperature resistance between 1MΩ·m and 20MΩ·m and a room temperature capacitance ≤0.5nF / m. It can be used for over-temperature alarm or fire detection within a range of room temperature to 700℃, thus improving the reliability of detection.

[0039] 4. The interaction and promotion between the materials in this invention give it good adaptability. All component materials will not oxidize or corrode the electrodes and outer protective sleeve. The resulting dual-parameter temperature-sensitive cable has good uniformity and consistency in resistance and capacitance parameters.

[0040] 5. This invention eliminates the chemical reaction between the sensitive dielectric material and the electrode and protective tube below 900℃, eliminates the impact of heat treatment on product performance, and has good process stability. This allows for the use of larger raw material outer tubes, resulting in a significant increase in the length of the finished product, greatly improving efficiency and reducing costs. By rationally designing the overall Pb3O4 content in the sensitive dielectric material and rationally designing and controlling the pre-sintering and sintering processes of BPT ferroelectric materials, BPTFeCr ferroelectric materials, MCT semiconductor ceramic materials, and temperature-sensitive dielectric materials for flame detectors, a temperature-sensitive dielectric material with a stable phase structure can be obtained. Attached Figure Description

[0041] Figure 1 It is a temperature-sensitive dielectric material for flame detectors. Detailed Implementation

[0042] like Figure 1 As shown, a temperature-sensitive dielectric material for a flame detector comprises the following components by weight: 8-9.5 parts of BPT ferroelectric material, wherein the weight parts of each component in the BPT ferroelectric material are: BaO 8-10 parts, TiO2 30-40 parts, Pb3O4 50-62 parts; 8-9.5 parts of BPTFeCr ferroelectric material, wherein the weight parts of each component in the BPTFeCr ferroelectric material are: BaO 8-10 parts, TiO2 29-34 parts, Pb3O4 49-54 parts, Fe2O3 1-2 parts, Cr2O3 7-9 parts; and 15-19 parts of MCT semiconductor ceramic material, wherein the weight parts of each component in the MCT semiconductor ceramic material are: Cr2O3 70-75 parts, MgO 24-28 parts, TiO2 1-3 parts. Fe2O3 7.5-8.5 parts, MnCO3 6.5-7.5 parts, Cr2O3 0.5-1 part, NaCl 2.3-3.5 parts, Ni2O3 1.5-2.5 parts, Al2O3 42-50.7 parts.

[0043] The preparation method of the temperature-sensitive dielectric material for flame detectors includes the following steps:

[0044] 1) Preparation of BPT ferroelectric materials;

[0045] 1-1) Ingredients: Take each component according to the proportions described for BPT ferroelectric materials, place them in an agate jar, add anhydrous ethanol, stir and mix at high speed, and dry for later use; uniform mixing can ensure that BPT ferroelectric materials with uniform composition are obtained.

[0046] 1-2) Pre-calcination: The powder obtained in step 1-1) is pre-calcined at 1000-1100℃ for 1.5-2.5 hours, cooled to room temperature, and then taken out and ball-milled into powder for later use. Pre-calcination can further ensure that the material is mixed evenly and that BPT ferroelectric material with uniform composition is obtained.

[0047] 1-3) Sintering: The powder obtained in step 1-2) is sintered at 1200-1300℃ for 1.5-2.5 hours, cooled to room temperature, and then ball-milled at high speed to obtain BPT ferroelectric material. Sintering ensures that the components react with each other to form BPT ferroelectric material.

[0048] 2) Preparation of BPTFeCr ferroelectric materials;

[0049] 2-1) Ingredients: Take each component according to the ratio described for BPTFeCr ferroelectric material, put them into an agate jar, add anhydrous ethanol, stir and mix at high speed, and dry for later use; uniform mixing can ensure that BPTFeCr ferroelectric material with uniform composition is obtained.

[0050] 2-2) Pre-calcination: The powder obtained in step 2-1) is pre-calcined at 1000-1100℃ for 1.5-2.5 hours, cooled to room temperature, and then taken out and ball-milled at high speed for later use; pre-calcination can further ensure that the material is mixed evenly and that BPTFeCr ferroelectric material with uniform composition is obtained.

[0051] 2-3) Sintering: The powder obtained in step 2-2) is sintered at 1200-1300℃ for 1.5-2.5 hours, cooled to room temperature, and then ball-milled at high speed to obtain BPTFeCr ferroelectric material. Sintering ensures that the components react with each other to form BPTFeCr ferroelectric material.

[0052] 3) Preparation of MCT semiconductor ceramic materials;

[0053] 3-1) Ingredients: Take each component according to the ratio described in the MCT semiconductor ceramic material, put them into an agate jar, add anhydrous ethanol, stir and mix at high speed, and dry for later use; uniform mixing can ensure that the MCT semiconductor ceramic material with uniform composition is obtained.

[0054] 3-2) Pre-firing: The powder obtained in step 3-1) is pre-firing at 1000-1100℃ for 1.5-2.5 hours. After cooling to room temperature, it is taken out and ball-milled at high speed for later use. Pre-firing can further ensure that the material is mixed evenly and obtain MCT semiconductor ceramic material with uniform composition.

[0055] 3-3) Sintering: The powder obtained in step 3-2) is sintered at 1250-1350℃ for 1.5-2.5 hours, cooled to room temperature, and then ball-milled at high speed to obtain MCT semiconductor ceramic material. Sintering ensures that the components react with each other to form MCT semiconductor ceramic material.

[0056] 4) Ingredients: Take each component according to the proportions described in claim 1, put them into an agate jar, add anhydrous ethanol, stir and mix at high speed, and dry for later use; uniform mixing can ensure that a temperature-sensitive medium material with uniform composition is obtained.

[0057] 5) Sintering: The powder prepared in step 4) is sintered at 1250℃~1300℃ for 45 hours, cooled to room temperature, and then ball-milled at high speed to obtain the temperature-sensitive dielectric material. Sintering ensures that the components react with each other to form the temperature-sensitive dielectric material.

[0058] During the preparation process, powder is loaded into a corundum crucible and sintered in a high-temperature sintering furnace.

[0059] Application of temperature-sensitive dielectric materials for flame detectors in the fabrication of temperature-sensitive cables for flame detectors.

[0060] 1) Preparation of BPT ferroelectric material: Weigh 500g BaO, 1800g TiO2, and 3000g Pb3O4, add 2000ml anhydrous ethanol, stir at high speed until uniform, and then dry. Place the dried material in an alumina crucible and pre-fire it in a high-temperature sintering furnace at 1070℃ for 2 hours. After cooling to room temperature, take it out and ball mill it into powder at high speed. Place the powder in an alumina crucible and sinter it in a high-temperature sintering furnace at 1200℃ for 2 hours. After cooling to room temperature, take it out and ball mill it into powder at high speed to obtain BPT ferroelectric material.

[0061] 2) Weigh 1400 g of Cr2O3, 550 g of MgO, and 110 g of TiO2, add 2000 ml of anhydrous ethanol, stir at high speed until uniform, and then dry. Place the dried material into an alumina crucible and pre-fire it in a high-temperature sintering furnace at 1070°C for 2 hours. After cooling to room temperature, take it out and ball-mill it into powder at high speed. Place the powder into an alumina crucible and sinter it in a high-temperature sintering furnace at 1260°C for 2 hours. After cooling to room temperature, take it out and ball-mill it into powder at high speed to obtain the MCT semiconductor ceramic material.

[0062] 3) Weigh 1400 g of Cr2O3, 550 g of MgO, and 110 g of TiO2, add 2000 ml of anhydrous ethanol, stir at high speed until uniform, and then dry. Place the dried material into an alumina crucible and place it in a high-temperature sintering furnace at 1070°C for 2 hours. After cooling to room temperature, take it out and ball mill it into powder at high speed. Place the powder into an alumina crucible and place it in a high-temperature sintering furnace at 1260°C for 2 hours. After cooling to room temperature, take it out and ball mill it into powder at high speed to obtain the MCT semiconductor ceramic material.

[0063] Example 1

[0064] According to Example 1 in Table 2, weigh each component of the temperature-sensitive medium material, add 4000 ml of anhydrous ethanol, stir at high speed until uniform, and then dry. Place the dried material into a corundum crucible and sinter it in a high-temperature sintering furnace at 1300°C for 5 hours. After cooling to room temperature, take it out and ball mill it into powder at high speed to obtain the temperature-sensitive medium material for flame detectors.

[0065] As shown in Table 3, Table 3 presents the results of testing at the China Academy of Testing Technology on a flame detector made from the temperature-sensitive dielectric material prepared in Example 1. The capacitance change rate C measured for the linear flame detector made from this temperature-sensitive material is... 500℃ / C 0℃ Reaching 250 or above.

[0066] Example 2

[0067] According to Example 2 in Table 2, weigh each component of the temperature-sensitive medium material, add 4000ml of anhydrous ethanol, stir at high speed until uniform, and then dry. Place the dried material into a corundum crucible and sinter it in a high-temperature sintering furnace at 1260℃ for 5 hours. After cooling to room temperature, take it out and ball mill it into powder at high speed to obtain the temperature-sensitive medium material for flame detectors.

[0068] As shown in Table 4, Table 4 presents the detection results of the flame detector made with the temperature-sensitive dielectric material obtained in Example 2. The capacitance change rate C measured by the linear flame detector made with this temperature-sensitive material is... 500℃ / C 25℃ Reaching 250 or above.

[0069] Example 3

[0070] According to Example 3 in Table 2, weigh each component of the temperature-sensitive medium material, add 4000 ml of anhydrous ethanol, stir evenly at high speed, and then dry. Place the dried material into a corundum crucible and sinter it in a high-temperature sintering furnace at 1250°C for 5 hours. After cooling to room temperature, take it out and ball mill it into powder at high speed to obtain the temperature-sensitive medium material for flame detectors.

[0071] As shown in Table 5, Table 5 presents the detection results of a flame detector made from the temperature-sensitive dielectric material obtained in Example 3. The capacitance change rate C measured for the linear flame detector made from this temperature-sensitive material is... 500℃ / C 25℃ Reaching 250 or above.

[0072] Example 4

[0073] According to Example 4 in Table 2, weigh each component of the temperature-sensitive medium material, add 4000 ml of anhydrous ethanol, stir at high speed until uniform, and then dry. Place the dried material into a corundum crucible and sinter it in a high-temperature sintering furnace at 1280°C for 5 hours. After cooling to room temperature, take it out and ball mill it into powder at high speed to obtain the temperature-sensitive medium material for flame detectors.

[0074] As shown in Table 6, Table 6 presents the detection results of a flame detector made from the temperature-sensitive dielectric material obtained in Example 4. The capacitance change rate C measured for the linear flame detector made from this temperature-sensitive material is... 500℃ / C 25℃ Reaching 250 or above.

[0075]

[0076] As can be seen from the above embodiments, the capacitance change rate C of the flame detector made of the temperature-sensitive dielectric material in these embodiments in Embodiment 1 is... 500℃ / C 0℃ Above 250, the capacitance change rate C of the flame detectors in Examples 2, 3, and 4 500℃ / C 25℃ All are above 250. The capacitance change rate C of the flame detector made with the temperature-sensitive dielectric material in Example 3 is... 500℃ / C 25℃ All are above 300.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A temperature-sensitive dielectric material for a flame detector, characterized in that: The weight percentages of each component in this temperature-sensitive dielectric material are as follows: BPT ferroelectric material 8–9.5 parts, BPTFeCr ferroelectric material 8–9.5 parts, MCT semiconductor ceramic material 15–19 parts, Fe2O3 7.5–8.5 parts, MnCO3 6.5–7.5 parts, Cr2O3 0.5–1 part, NaCl 2.3–3.5 parts, Ni2O3 1.5–2.5 parts, Al2O3 42–50.7 parts; The weight parts of each component in the BPT ferroelectric material are: BaO 8-10 parts, TiO2 30-40 parts, and Pb3O4 50-62 parts; The weight parts of each component in the BPTFeCr ferroelectric material are as follows: BaO 8-10 parts, TiO2 29-34 parts, Pb3O4 49-54 parts, Fe2O3 1-2 parts, and Cr2O3 7-9 parts; The weight parts of each component in the MCT semiconductor ceramic material are as follows: Cr2O3 70-75 parts, MgO 24-28 parts, and TiO2 1-3 parts.

2. The method for preparing the temperature-sensitive dielectric material for flame detectors according to claim 1, characterized in that, Includes the following steps: 1) Preparation of BPT ferroelectric materials; 1-1) Ingredients: Take each component according to the proportions described in claim 1, add anhydrous ethanol, stir and mix, and dry; 1-2) Pre-calcination: The powder obtained in step 1-1) is pre-calcined at 1000-1100℃ for 1.5-2.5 hours, cooled to room temperature, and then ball-milled into powder. 1-3) Sintering: The powder obtained by pre-sintering is sintered at 1200-1300℃ for 1.5-2.5 hours, cooled to room temperature and then taken out and ball-milled into powder to obtain BPT ferroelectric material; 2) Preparation of BPTFeCr ferroelectric materials; 2-1) Ingredients: Take each component according to the proportions described in claim 1, add anhydrous ethanol, stir and mix, and dry; 2-2) Pre-calcination: The powder obtained in step 2-1) is pre-calcined at 1000-1100℃ for 1.5-2.5 hours, cooled to room temperature, and then ball-milled into powder. 2-3) Sintering: The powder obtained by pre-sintering is sintered at 1200-1300℃ for 1.5-2.5 hours, cooled to room temperature and then taken out and ball-milled into powder to obtain BPTFeCr ferroelectric material; 3) Preparation of MCT semiconductor ceramic materials; 3-1) Ingredients: Take each component according to the proportions described in claim 1, add anhydrous ethanol, stir and mix, and dry; 3-2) Pre-calcination: The powder obtained in step 3-1) is pre-calcined at 1000-1100℃ for 1.5-2.5 hours, cooled to room temperature, and then ball-milled into powder. 3-3) Sintering: The powder obtained by pre-sintering is sintered at 1250-1350℃ for 1.5-2.5 hours, cooled to room temperature, removed, and ball-milled into powder to obtain MCT semiconductor ceramic material; 4) Ingredients: Take each component according to the proportions described in claim 1, add anhydrous ethanol, stir and mix, and dry; 5) Sintering: Sinter the powder prepared in step 4) at 1250℃~1300℃ for 4~5 hours, cool to room temperature and then ball mill it into powder to obtain the temperature-sensitive medium material.

3. The method according to claim 2, characterized in that: During the preparation process, powder is loaded into a corundum crucible and sintered in a high-temperature sintering furnace.

4. The application of the temperature-sensitive dielectric material for flame detectors as described in claim 1 in the preparation of temperature-sensitive cables for flame detectors.

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