阅读说明：本技术 适用于通用航空尾气排放测温的复合负温度系数热敏电阻及其制备方法 (Composite negative temperature coefficient thermistor suitable for general aviation exhaust emission temperature measurement and preparation method thereof ) 是由 张博 付志龙 刘亚飞 常爱民 于 2020-07-03 设计创作，主要内容包括：本发明涉及一种适用于通用航空尾气排放测温的复合负温度系数热敏电阻及其制备方法,该热敏电阻以碳酸钙,二氧化铈,五氧化二铌,三氧化钨,三氧化二镧和二氧化锰为原料,经混合研磨、煅烧、再混合研磨、冷等静压成型、高温烧结工艺、被电极工艺过程,得到具有特殊结构为烧绿石相CaCeNbWO<Sub>8</Sub>和钙钛矿相LaMnO<Sub>3</Sub>的复合NTC热敏电阻,其致密度为89%-95%,材料常数为<I>B</I><Sub><I>2</I>00℃/1100℃</Sub>=44 K-10889 K,在温度850℃时,电阻率为4.26×10<Sup>2</Sup>Ωcm-1.76×10<Sup>5</Sup>Ωcm。本发明所述的复合NTC热敏电阻可应用于温度200-1100℃环境下的温度监测和控制,具有明显的负温度系数特性,高温性能稳定,抗老化性好,适用于通用航空尾气排放测温。(The invention relates to a composite negative temperature coefficient thermistor suitable for measuring temperature of general aviation exhaust emission and a preparation method thereof 8 And perovskite phase LaMnO 3 The composite NTC thermistor has a compactness of 89-95% and a material constant of B 2 00℃/1100℃ = 44K-10889K, and the resistivity is 4.26 × 10 at 850 deg.C 2 Ωcm‑1.76×10 5 Omega cm. The composite NTC thermistor can be applied to temperature monitoring and control in the environment with the temperature of 200-1100 ℃, has obvious negative temperature coefficient characteristics, stable high-temperature performance and good aging resistance, and is suitable for measuring the temperature of the tail gas emission of general aviation.)

1. A composite negative temperature coefficient thermistor suitable for measuring temperature of general aviation exhaust emission is characterized in that calcium carbonate, cerium dioxide, niobium pentoxide, tungsten trioxide, lanthanum trioxide and manganese dioxide are used as raw materials, and the chemical composition of the thermistor is (1-x)CaCeNbWO₈-xLaMnO₃Wherein 0 is less than or equal toxNot more than 1.0 and the structure is pyrochlore phase CaCeNbWO₈And perovskite phase LaMnO₃The method comprises the following specific operation steps:

preparation of pyrochlore phase CaCeNbWO₈：

a. According to CaCeNbWO₈Respectively weighing calcium carbonate, cerium dioxide, niobium pentoxide and tungsten trioxide raw materials according to the molar ratio, placing the raw materials into an agate mortar, mixing and grinding the raw materials for 6 to 10 hours, then calcining the mixture for 3 hours at the temperature of 1000 to 1200 ℃, and grinding the mixture for 6 to 10 hours again to obtain the dispersed single-phase CaCeNbWO₈Powder;

preparation of perovskite phase LaMnO₃：

b. According to LaMnO₃Respectively weighing lanthanum sesquioxide and manganese dioxide raw materials according to the molar ratio, placing the raw materials into an agate mortar, mixing and grinding the raw materials for 6 to 10 hours, then calcining the raw materials for 2 hours at the temperature of 900 to 1100 ℃, and grinding the raw materials for 6 to 10 hours again to obtain dispersed single-phase LaMnO₃Powder;

preparing a composite negative temperature coefficient thermistor:

c. the single-phase powder obtained in the step a and the step b is divided into (1-x)CaCeNbWO₈-xLaMnO₃Is composed of (a) whereinx=0.1,0.3,0.5,0.7 and 0.9, respectively put in different agate mortars to be mixed and ground for 6-10h to obtainxMixed powder materials with various proportions of =0.1,0.3,0.5,0.7 and 0.9;

d. c, molding the mixed powder with various proportions obtained in the step c by using a mold with the diameter of 10mm respectively to obtain green body materials with various proportions;

e. d, performing vacuum packaging on the green body material obtained in the step d, performing cold isostatic pressing for 1-3min under the pressure of 200-300MPa, then sintering for 6-9h at the temperature of 1200-1400 ℃, and cooling to room temperature to obtain wafer-shaped high-density composite ceramic block materials in various proportions;

f. e, treating the block ceramic material obtained in the step e for 30min at 900 ℃ by using a platinum slurry electrode, and cooling to room temperature to obtain the block ceramic material with the density of 89-95% and the material constant ofB _{200℃/1100℃}The structure of the material is pyrochlore phase CaCeNbWO = 44K-10889K₈And perovskite phase LaMnO₃The composite negative temperature coefficient thermistor.

2. A preparation method of a composite negative temperature coefficient thermistor suitable for measuring temperature of general aviation exhaust emission is characterized by comprising the following steps:

preparation of pyrochlore phase CaCeNbWO₈：

a. According to CaCeNbWO₈Respectively weighing calcium carbonate, cerium dioxide, niobium pentoxide and tungsten trioxide raw materials according to the molar ratio, placing the raw materials into an agate mortar, mixing and grinding the raw materials for 6 to 10 hours, then calcining the mixture for 3 hours at the temperature of 1000 to 1200 ℃, and grinding the mixture for 6 to 10 hours again to obtain the dispersed single-phase CaCeNbWO₈Powder;

preparation of perovskite phase LaMnO₃：

b. According to LaMnO₃Respectively weighing lanthanum sesquioxide and manganese dioxide raw materials according to the molar ratio, placing the raw materials into an agate mortar, mixing and grinding the raw materials for 6 to 10 hours, then calcining the raw materials for 2 hours at the temperature of 900 to 1100 ℃, and grinding the raw materials for 6 to 10 hours again to obtain dispersed single-phase LaMnO₃Powder;

preparing a composite negative temperature coefficient thermistor:

c. the single-phase powder obtained in the step a and the step b is divided into (1-x)CaCeNbWO₈-xLaMnO₃Is composed of (a) whereinx=0.1,0.3,0.5,0.7 and 0.9, respectively put in different agate mortars to be mixed and ground for 6-10h to obtainxMixed powder materials with various proportions of =0.1,0.3,0.5,0.7 and 0.9;

d. c, molding the mixed powder with various proportions obtained in the step c by using a mold with the diameter of 10mm respectively to obtain green body materials with various proportions;

e. d, performing vacuum packaging on the green body material obtained in the step d, performing cold isostatic pressing for 1-3min under the pressure of 200-300MPa, then sintering for 6-9h at the temperature of 1200-1400 ℃, and cooling to room temperature to obtain wafer-shaped high-density composite ceramic block materials in various proportions;

f. e, treating the block ceramic material obtained in the step e for 30min at 900 ℃ by using a platinum slurry electrode, and cooling to room temperature to obtain the block ceramic material with the density of 89-95% and the material constant ofB _{200℃/1100℃}The structure of the material is pyrochlore phase CaCeNbWO = 44K-10889K₈And perovskite phase LaMnO₃The composite negative temperature coefficient thermistor.

3. The method for preparing the composite negative temperature coefficient thermistor suitable for measuring the temperature of the general aviation exhaust emission according to claim 2, wherein the green body material in the step e is subjected to pressure holding for 3min under 300MPa and is sintered for 9h at 1350 ℃.

Technical Field

The invention relates to a composite negative temperature coefficient thermistor suitable for measuring temperature of general aviation exhaust emission and a preparation method thereof, wherein the thermistor ceramic material has obvious Negative Temperature Coefficient (NTC) characteristic in the temperature range of 200-1100 ℃, and is a novel thermistor material suitable for manufacturing a high-stability high-temperature thermistor.

Background

With the development of general aviation industry in China, particularly the development of general aviation industry in the future in Xinjiang, the number of aviation piston engines is increased sharply, and the requirement on the economy of the piston engines is higher and higher. Currently, many pilots adjust the fuel mixture ratio with the exhaust temperature to achieve increased range. The exhaust temperature refers to the exhaust gas temperature detected at the exhaust pipe of the engine and is an important parameter for the normal operation of the piston type aircraft engine. Most piston aircraft engines have an exhaust gas temperature sensor and an exhaust gas temperature indicator. The exhaust temperature sensor is essentially a thermocouple or a thermal resistor. The performance parameters of an aircraft engine are typically analyzed by combining engine power, fuel economy, and exhaust temperature profiles for the engine. The exhaust temperature is a parameter reflecting the combustion condition of the gas-fuel mixture in each cylinder of the engine, and the condition of the mixture ratio of fuel and air entering the cylinder can be known by observing the exhaust temperature value. When the ratio of fuel to air is a particular value, the fuel and air entering the cylinder are just burned completely separately, and the measured exhaust temperature is the highest, referred to as the peak exhaust temperature. In order to stably work at various flying heights in the process of taking off and landing, the piston type aircraft engine needs to set the oil-gas mixing ratio by observing the exhaust temperature peak value before taking off from the ground. The peak value of the exhaust temperature of the aircraft engine rises along with the increase of the output power of the engine, and the highest peak value of the exhaust temperature of most piston type aircraft engines is about 854 ℃. Thus, the exhaust temperature peak becomes the most important parameter for developing the temperature sensor. This puts higher demands on the high temperature resistance and high temperature stability of the temperature measuring core element of the thermistor temperature sensor.

Because Negative Temperature Coefficient (NTC) thermistors have the characteristics of high sensitivity and fast response and are widely applied, and because the development of the traditional Mn-Co-Ni-O spinel type thermistor material system and the novel perovskite type thermistor material system to the field of higher temperature or harsher environment is still limited, the development of novel wide-temperature-region high-temperature-resistant thermistor materials faces new challenges. The oxide ceramic material has the characteristics of oxidation resistance, high temperature resistance, corrosion resistance, high hardness, wear resistance and the like, but the high density of the oxide ceramic applied to the NTC thermistor is required, which is beneficial to prolonging the service life of the NTC thermistor. The ceramic matrix composite has the advantages that the density of the thermosensitive ceramic material can be greatly improved, and the toughness can be improved by refining crystal grains, so that the defect of the single-phase ceramic material is just made up for.

The invention is realized by the reaction of (1-x) CaCeNbWO₈-xLaMnO₃(x is more than or equal to 0 and less than or equal to 1.0) the microstructure and electrical property analysis of the composite negative temperature coefficient thermistor shows that: 0.7CaCeNbWO₈-0.3LaMnO₃The logarithmic resistivity of the composite NTC thermistor is in a function relationship with the reciprocal temperature close to linearity, and has high sensitivity and high temperature stability. The composite NTC thermistor can show good NTC characteristics from 200 ℃ to 1100 ℃, and is expected to be applied to a general aviation exhaust emission temperature measurement system.

Disclosure of Invention

The invention aims to provide a composite NTC thermistor suitable for general aviation exhaust emission temperature measurement and a preparation method thereof aiming at the requirements of high-temperature negative temperature coefficient thermistors in high-temperature special environments such as aviation exhaust emission and the like and the problems in the prior artObtaining the CaCeNbWO with the pyrochlore phase as a special structure₈And perovskite phase LaMnO₃The density of the composite negative temperature coefficient thermistor is 89-95%, and the material constant is B_{200℃/1100℃}44K-10889K, a resistivity of 4.26 × 10 at 850 ℃²Ωcm-1.76×10⁵Omega cm. The composite negative temperature coefficient thermistor can be applied to temperature monitoring and control in the environment with the temperature of 200-1100 ℃, has obvious NTC characteristics, stable high-temperature performance and good aging resistance, and is suitable for measuring the temperature of the tail gas emission of general aviation.

The invention relates to a composite negative temperature coefficient thermistor suitable for measuring temperature of general aviation exhaust emission, which takes calcium carbonate, cerium dioxide, niobium pentoxide, tungsten trioxide, lanthanum trioxide and manganese dioxide as raw materials, and has the chemical composition of (1-x) CaCeNbWO₈-xLaMnO₃Wherein x is more than or equal to 0 and less than or equal to 1.0, and the structure is pyrochlore phase CaCeNbWO₈And perovskite phase LaMnO₃The method comprises the following specific operation steps:

preparation of pyrochlore phase CaCeNbWO₈：

a. According to CaCeNbWO₈Respectively weighing calcium carbonate, cerium dioxide, niobium pentoxide and tungsten trioxide raw materials according to the molar ratio, placing the raw materials into an agate mortar, mixing and grinding the raw materials for 6 to 10 hours, then calcining the mixture for 3 hours at the temperature of 1000 to 1200 ℃, and grinding the mixture for 6 to 10 hours again to obtain the dispersed single-phase CaCeNbWO₈Powder;

preparation of perovskite phase LaMnO₃：

b. According to LaMnO₃Respectively weighing lanthanum sesquioxide and manganese dioxide raw materials according to the molar ratio, placing the raw materials into an agate mortar, mixing and grinding the raw materials for 6 to 10 hours, then calcining the raw materials for 2 hours at the temperature of 900 to 1100 ℃, and grinding the raw materials for 6 to 10 hours again to obtain dispersed single-phase LaMnO₃Powder;

preparing a composite negative temperature coefficient thermistor:

c. mixing the single-phase powder obtained in step a and step b according to the formula of (1-x) CaCeNbWO₈-xLaMnO₃The composition is that x is 0.1,0.3,0.5,0.7 and 0.9, and the mixture is respectively put into different agate mortars to be mixed and ground for 6 to 10 hours to obtain x is 0.1,0.3,0.5 and 07,0.9 mixing powder materials in various proportions;

d. c, molding the mixed powder with various proportions obtained in the step c by using a mold with the diameter of 10mm respectively to obtain green body materials with various proportions;

e. d, performing vacuum packaging on the green body material obtained in the step d, performing cold isostatic pressing for 1-3min under the pressure of 200-300MPa, then sintering for 6-9h at the temperature of 1200-1400 ℃, and cooling to room temperature to obtain wafer-shaped high-density composite ceramic block materials in various proportions;

f. e, treating the block ceramic material obtained in the step e for 30min at 900 ℃ by using a platinum slurry electrode, and cooling to room temperature to obtain the block ceramic material with the density of 89-95% and the material constant of B_{200℃/1100℃}44K-10889K has the structure of pyrochlore phase CaCeNbWO₈And perovskite phase LaMnO₃The composite negative temperature coefficient thermistor.

A preparation method of a composite negative temperature coefficient thermistor suitable for measuring temperature of general aviation exhaust emission comprises the following steps:

preparation of pyrochlore phase CaCeNbWO₈：

a. According to CaCeNbWO₈Respectively weighing calcium carbonate, cerium dioxide, niobium pentoxide and tungsten trioxide raw materials according to the molar ratio, placing the raw materials into an agate mortar, mixing and grinding the raw materials for 6 to 10 hours, then calcining the mixture for 3 hours at the temperature of 1000 to 1200 ℃, and grinding the mixture for 6 to 10 hours again to obtain the dispersed single-phase CaCeNbWO₈Powder;

preparation of perovskite phase LaMnO₃：

b. According to LaMnO₃Respectively weighing lanthanum sesquioxide and manganese dioxide raw materials according to the molar ratio, placing the raw materials into an agate mortar, mixing and grinding the raw materials for 6 to 10 hours, then calcining the raw materials for 2 hours at the temperature of 900 to 1100 ℃, and grinding the raw materials for 6 to 10 hours again to obtain dispersed single-phase LaMnO₃Powder;

preparing a composite negative temperature coefficient thermistor:

c. mixing the single-phase powder obtained in step a and step b according to the formula of (1-x) CaCeNbWO₈-xLaMnO₃The components are respectively put into different agate mortars to be mixed and ground for 6 to 10 hours to obtain x which is 0.1,0.3,0.5,0.7 and 0.9Mixing powder materials in different proportions;

d. c, molding the mixed powder with various proportions obtained in the step c by using a mold with the diameter of 10mm respectively to obtain green body materials with various proportions;

e. d, performing vacuum packaging on the green body material obtained in the step d, performing cold isostatic pressing for 1-3min under the pressure of 200-300MPa, then sintering for 6-9h at the temperature of 1200-1400 ℃, and cooling to room temperature to obtain wafer-shaped high-density composite ceramic block materials in various proportions;

f. e, treating the block ceramic material obtained in the step e for 30min at 900 ℃ by using a platinum slurry electrode, and cooling to room temperature to obtain the block ceramic material with the density of 89-95% and the material constant of B_{200℃/1100℃}44K-10889K has the structure of pyrochlore phase CaCeNbWO₈And perovskite phase LaMnO₃The composite negative temperature coefficient thermistor.

And e, keeping the pressure of the green body material in the step e at 300MPa for 3min, and sintering at 1350 ℃ for 9 h.

The invention relates to a composite negative temperature coefficient thermistor suitable for measuring temperature of general aviation exhaust emission and a preparation method thereof, wherein the method comprises the following steps: the preparation method comprises the following steps of structural design, proportioning, mixing and grinding, calcining, mixing and grinding again, cold isostatic pressing, high-temperature sintering and electrode operation process flow to realize the preparation of the high-temperature composite NTC thermistor. The obtained high-temperature composite negative temperature coefficient thermistor has high density, namely good aging resistance, good thermal stability, simple process, environmental friendliness and low cost, can be produced in large scale, and can endure high temperature for a long time and adapt to the working requirements of special environments such as high temperature and the like.

Compared with the prior art, the invention has the following advantages:

1) the invention realizes the high-density high-temperature NTC thermistor which can be applied to the wide temperature range of 200-1100 ℃ and used for a long time for the first time;

2) the preparation method solves the problems of low sensitivity, low temperature resistance and narrow measurement temperature zone of the temperature measuring element in high-temperature special environments such as general aviation exhaust emission temperature monitoring and the like, and provides technical support for stable application of the high-temperature thermistor in the high-temperature special environments and the like;

3) the invention utilizes CaCeNbWO with pyrochlore structure₈And LaMnO having perovskite structure₃The preparation of the high-density composite NTC thermistor is realized under normal pressure by combining the high-temperature structures of the phases, the process has low requirement on equipment, less investment at one time and simple operation process, and can realize mass production;

4) the high-temperature NTC thermistor obtained by the invention can be applied to temperature monitoring and control in the environment of 200-1200 ℃, meanwhile, the molar ratio in the preparation method is controllable, and the obtained composite negative temperature coefficient thermistor has good ageing resistance, good thermal stability, high sensitivity and stable electrical performance.

Drawings

FIG. 1 is an X-ray diffraction pattern of the present invention;

FIG. 2 is a temperature resistance characteristic curve according to the present invention.

Detailed Description