Conventional NTC chips are generally made of NTC heat-sensitive materials made of transition metal manganese, iron, cobalt, nickel, and copper oxides. Due to the low volatilization temperature of these transition metal oxides, it is easy to cause the volatilization of raw material components during the sintering process, which makes it difficult to control the final product composition, product consistency, and repeatability between different batches of production. Therefore, the room temperature resistivity of this type of thermosensitive material is greatly affected by processes such as sintering temperature, sintering atmosphere, and cooling rate. At the same time, the widely used NTC chip with a spinel structure is prone to slowly redistribute cations in the tetrahedron and octahedron during use, causing structural relaxation. This relaxation phenomenon causes the instability of the electrical properties of the NTC ceramic material, easily leads to the aging of the NTC chip, and affects the temperature measurement accuracy of the thermal chip.
As industries such as refrigerators, air conditioners, microwave equipment, automobiles, optical communications, and aerospace have increasingly demanded the stability of NTC chips, it is very important to improve existing component systems or develop new component systems. In view of the above problems, we recommend an NTC chip prepared by changing the content of doped elements with nickel-magnesium-zinc oxide solid solution as the main component. The NTC thermal chip has stable performance and high reliability. The material composition of this NTC chip is: [(Ni1-xZnx)1-yMgy]1-wLiwO, where x=0.0001~0.4, y=0~0.6, w=0~0.1. The initial raw materials are selected from zinc oxide ZnO, basic nickel carbonate NiCO3·2Ni(OH)2·4H2O. The preparation of NTC chip is carried out according to the following process steps:
1. The initial raw materials are mixed according to the Ni0.7Zn0.3O formula, and the zinc oxide ZnO 2.4422g and the basic nickel carbonate NiCO3·2Ni(OH)2·4H2O 8.7775g are weighed with an analytical balance;
2. Dissolve the weighed raw materials in 15% dilute nitric acid aqueous solution;
3. Mix the two solutions prepared together, and use a magnetic stirring heater to stir and mix evenly, heat and dry;
4. The obtained precursor powder is calcined in an air environment, the heating rate is 5°C/min, the calcining temperature is 1000°C, and the temperature is kept for 5 hours;
5. Use the pre-prepared polyvinyl alcohol aqueous solution as a binder to granulate the calcined synthesized powder, and then press it into a green body;
6. The green body is sintered in an air environment, the sintering temperature is 1330℃, the heat preservation is 2 hours, the heating rate is 5℃/min, and the NTC thermal ceramic sheet is obtained;
7. The electrode paste is printed on both ends of the NTC thermal ceramic sheet and cured at 600℃;
8. Measure the resistance-temperature characteristics of the NTC chip obtained by the dicing.
Miss Lei
15622503218
follow