High use temperature lead-free PTCR (positive temperature coefficient resistance) ceramic and preparation method thereof
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A ceramic and formula technology, applied in the field of high service temperature lead-free PTCR ceramics and its preparation, to achieve the effects of improving microstructure, promoting semiconducting, and reducing normal temperature resistivity
Inactive Publication Date: 2015-02-25
TONGREN UNIV
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Problems solved by technology
Judging from the current literature reports, there is no research on the withstand voltage characteristics of lead-free PTCR materials. Since the withstand voltage strength determines the maximum working voltage that PTCR ceramics can withstand, it is also an extremely important parameter for materials.
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Embodiment 1
[0026] In an embodiment of the present invention, a method for preparing a lead-free PTCR ceramic with a high service temperature, the specific steps are as follows:
[0027] Take x1=0.15, A is Y, x2=0.002, B is Mn, y=0.001, M is SiO 2 , z=1, then the molecular formula is (Na 0.5 Bi 0.5 ) 0.15 (Ba 0.848 Y 0.002 ) Ti 0.999 mn 0.001 o 3 +1mol%SiO 2 composition of ceramics. Using high-purity TiO 2 、BaCO 3 、Na 2 CO 3 、 Bi 2 o 3 , Y 2 o 3 , MnO 2 , SiO 2 As a raw material, it is weighed according to the stoichiometry of the main components of the above chemical formula.
[0028] Alcohol is used as the ball milling medium, and agate balls are used for ball milling and mixing, and then pressed into blocks after drying. Heat preservation at 900°C for 2 hours in the air for pre-synthesis, after crushing, add modifier and then ball mill, dry, add binder, molding, plastic discharge, heat preservation at 1220°C for 4 hours, sintering in nitrogen atmosphere, processing,...
Embodiment 2-18
[0030] The Curie temperature of materials and their electrical properties can be adjusted by changing different substitution components and additives. TiO 2 , CaCO 3 , SrCO 3 、BaCO 3 、Na 2 CO 3 、 Bi 2 o 3 , Y 2 o 3 , La 2 o 3 , Nb 2 o 5 、 Ta 2 o 5 , Sb 2 o 5 , MnO 2 , CuO, ZrO 2 , SnO 2 、Al 2 o 3 , SiO 2 , B 2 o 3 etc. are raw materials, according to the chemical composition listed in Table 1, according to the chemical formula (Na 0.5 Bi 0.5 ) x1 (Ba 1-x1 - x2 A x2 ) Ti 1-y B y o 3 Stoichiometric weighing of +zmol%M. Other process conditions are the same as in Example 1. For different x1 values, the sintering temperature is between 1180-1230° C., and its properties are listed in Table 1.
[0031] Composition and performance table of table 1 embodiment 1-16
[0032]
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Abstract
The invention discloses a high use temperature lead-free PTCR (positive temperature coefficient resistance) ceramic and a preparation method thereof, and belongs to the field of lead-free electronic ceramic materials. A general formula of the material composition is as follows: (Na0.5Bi0.5)x1 (Ba1-x1-x2Ax2) Ti1-yByO3+zmol%M), wherein x1 is greater than or equal to 0.08 and less than or equal to 0.6, x2 is greater than or equal to 0 and less than or equal to 0.2, y is greater than or equal to 0 and less than or equal to 0.05, z is greater than or equal to 0 and less than or equal to 3, A is one or more of Sr, Ca, Bi, Y and La, B is one or more of Zr, Sn, Mn, Cu, Nb, Ta and Sb, and M is one or more of Al2O3, SiO2, TiO2, BaO and B2O3. The high use temperature lead-free PTCR ceramic prepared by method has the following performance indicators: Curie temperature is at 175 to 235 DEG C; resistance jump ratio is 2 to 5 orders of magnitude; room temperature resistivity is 60-106 Omega .cm; temperature coefficient of resistance is 10-20% / DEG C; and withstand voltage strength is 150-220V / mm (a.c.). A ceramic sample is prepared in nitrogen by one-step sintering method, and has the advantages of simple controllable process, stable material performance and good repeatability.
Description
technical field [0001] The invention relates to a lead-free PTCR (positive temperature coefficient resistance) ceramic with high service temperature and a preparation method thereof, belonging to the field of lead-free electronic ceramic materials. It can be used to make various temperature sensors, current limiting protection, color TV degaussing, motor starting, high temperature heating, etc. It is widely used in electronic information, aerospace equipment, medical and health care, household appliances and other fields. Background technique [0002] The resistivity of PTCR ceramic materials decreases with the increase of temperature below the Curie temperature, which is a negative temperature coefficient resistance effect (NTC effect), and at the Curie temperature T c At , the material undergoes a ferroelectric-paraelectric phase transition, and the room temperature resistivity increases sharply by several orders of magnitude, which is the positive temperature coefficient ...
Claims
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Application Information
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