NTC thermistor is widely used in temperature monitoring, temperature controlling, protection of circuits and electronic components, as well as flow velocity, flow, gamma ray measurement of related instruments and application field. As household appliances, microwave equipment and new energy automobile have higher and higher requirements for the stability of NTC thermistor, it is very important to improve the existing ingredient system or develop new ingredient system.
In the common NTC thermistor, thermistor materials are semiconductor ceramics made of two or more transition metal oxides such as manganese, copper, cobalt, iron, nickel and zinc, which are fully mixed, formed and sintered. Due to the low volatilization temperature of these transition metal oxides, they are easily volatilized during the preparation and sintering process, which makes the final composition of the product and the consistency of the product difficult to control. The room temperature resistivity of spinel structure NTC thermistor material is generally larger, and the resistance value is not easy to adjust. Reducing the resistivity of the material will lead to a decrease in the temperature coefficient and affect the properties of the thermistor.
In order to solve the above technical problems, EXSENSE Electronics recommends a high-performance NTC thermistor material, which is not only suitable for the granary thermometer, but also can be applied in temperature measurement of food storage, medicine and health, scientific farming, ocean, high altitude, glaciers and other fields. This high-performance NTC thermistor material takes copper oxide as the main component, by doping the modified material with trace elements, a thermistor material system with good NTC effect can be obtained, and the room temperature resistivity of the thermistor and the temperature constant of the material can be adjusted by changing the trace doping elements.
High-performance NTC thermistor material is composed of Cu1-X-YYXTIYO, where x=0.001~0.09; y=0.01~0.07. Yttrium is semiconducting element that adjusts the room temperature resistance and material constants of the material. The purpose of titanium is to adjust the room temperature resistivity of the thermistor and the material constant and temperature coefficient reflecting the thermistor's thermal characteristics. At the same time, the introduction of titanium can also enhance the sinterability of thermistor. This formula contains copper, titanium and yttrium metal elements, its raw materials can be elementary substance, oxides, inorganic salts or metal-organic compounds containing these elements, etc. The NTC thermistor prepared by using this material has stable performance and great reliability.
The high-performance NTC thermistor material is mixed according to the molecular formula Cu1-X-YYXTiYO, where X=0.008, Y=0.01. The initial raw materials are selected from copper hydroxide Cu(OH)2, tetrabutyl titanate TBT, yttrium Y2O3. The material preparation is carried out according to the following experimental process steps:
First, according to the formula of Cu0.982Y0.008Ti0.01O, the initial raw materials of Cu(OH)2 19.1580g, Y2O3 0.1806g, TBT 0.6806g are weighed;
Second, the raw materials of Cu(OH)2, Cu(OH)2 and TBT are respectively dissolved in dilute nitric acid;
Third, the three solutions are mixed together, and the magnetic stirring heater is used to stir and mix evenly, heated and dried;
Fourth, the prepared precursor powder is sintered at 830℃ and held for 6 hours;
Fifth, the sintered powder is granulated and pressed into a blank with thickness of 3.5~4.0mm;
Sixth, the blank is sintered with sintering temperature of 990℃ and held for 6 hours at a heating and cooling rate of 5℃ per minute to obtain NTC thermal ceramic slice;
Seventh, after grinding both sides of the NTC thermal ceramic slice, the silver electrode is printed;
Eighth, the NTC thermistor is measured for resistance - temperature characteristics.
The features and advantages of this high-performance NTC thermistor material are:
First, the material composition is simple, the raw material is relatively rich, non-toxic;
Second, the sintering temperature is 1000±50℃ during the preparation process, which is suitable for the production of NTC thermistor components such as ceramic components and low temperature co-firing;
Third, the room temperature resistance of thermistor can be adjusted widely by adjusting the content of semiconducting doped elements;
Fourth, the material constant and temperature coefficient of NTC thermistor can be greatly adjusted by adjusting the content of titanium in the composition.