CN105753454A - Thermal sensitive ceramic material with low electrical resistivity and negative temperature coefficient and preparation method thereof - Google Patents

Abstract

The invention discloses a thermal sensitive ceramic material with low electrical resistivity and a negative temperature coefficient and a preparation method thereof. The thermal sensitive ceramic material is prepared from the following raw materials in parts by weight: 30-40 parts of Mn3O4, 35-40 parts of Co3O4, 20-25 parts of CuO, 10-20 parts of La2O3, 5-10 parts of CaO, 35-45 parts of MnO2, 30-40 parts of Ni2O3, 0.24-0.4 part of Fe2O3, 0.15-0.25 part of C, 0.21-0.35 part of TiO2, 0.09-0.15 part of Cr2O3, 0.05-0.06 part of Nb2O5 and 0.05-0.07 part of Nd2O3. The obtained thermal sensitive ceramic material is capable of achieving relatively small electrical resistivity under a condition of slightly influencing a material constant B value, reducing the porosity, and improving the pulse performance of the material in a situation of inhibiting a surge current field.

Description

A kind of thermal sensitive ceramic material of low-resistivity negative temperature coefficient and preparation method thereof

Technical field

The present invention relates to a kind of ceramic material, the thermal sensitive ceramic material of a kind of low-resistivity negative temperature coefficient and preparation thereof Method.

Background technology

Negative temperature coefficient (NTC) thermistor, because of its have that temperature measurement accuracy is high, interchangeability is good, reliability is high, with low cost Etc. advantage, in temperature survey, control, compensate and the many-side such as long-range control of communication apparatus is widely used, recognize For being the electronic devices and components with tremendous expansion potentiality, there is good application prospect.Generally AB2O4 type spinel structure Being the principal crystalline phase of NTC thermal sensitive ceramic material, along with science and technology and the development of demand, the limitation of this kind of material also becomes increasingly conspicuous. When the resistivity of material is higher, its B value is the highest, and vice versa, the polynary system ceramic material that spinel structure forms simultaneously Less stable, the pottery after sintering is in nonequilibrium condition, causes material electric property to change, and these 2 constrain NTC The wide application of temperature-sensitive element.

Low-resistivity, the preparation of high B-value negative temperature coefficient thermo-sensitive material are to manufacture high-sensitivity thermosensitive resistance and sensor thereof Core technology.The slice heat sensitive resistor single-layered (i.e. by single layer of chips) of sandwich construction depends on low-resistivity, high B value material Exploitation.Power-type surge temperature-sensitive resistance requirement low-resistivity, high B value material, to reduce the residual resistance of element, reduce Power dissipation on resistive element, improves the overload capacity of product.Inspection (such as the bioengineering) requirement of some shallow temperature signals Sensor has the highest sensitivity, and low-resistivity, high B value thermistor composition are always the target that people pursue.

In order to improve the B value of thermo-sensitive material, reduce material resistance, in transition-metal oxide material prescription, once mixed your gold Belong to, as Au, Pt, Pa utilize the shunt effect of metal ion to reduce the resistivity of material, but along with under resistivity of material Fall, B value significantly declines, and the material of 5 Ω cm resistivity, B value can only achieve 2600K.People is had the most again to join at material Side adds some low-valent metal such as K, the oxide of Na, Ca, is to reduce resistivity equally, also reduces B value, it is impossible to Realize low-resistivity, high B value thermistor composition that application requires.

According to the character of oxide semiconductor, resistivity of material (inverse of electrical conductivity) depends primarily on the friendship of atoms outermost electronics Changing, B value is decided by the size (Δ E/K) of carrier activation energy.To the activation energy that holding is higher, can maintain in conduction band again and have Bigger carrier concentration, the level structure of the material that only changes, in forbidden band, i.e. form magazine energy level, use the knot of material Structure is combined, and makes to have the material (such as inverse spinel, or the spinelle that is all-trans) of low-resistivity with high B value material (such as perovskite structure And rutile structure) form composite structure network, utilize structure " additive effect ", it is achieved being combined of material behavior, to obtain Low-resistivity, the thermo-sensitive material of high B value.

Summary of the invention

It is an object of the invention to provide the thermal sensitive ceramics material of the low-resistivity negative temperature coefficient that a kind of uniformity is good, stability is high Material and preparation method thereof, with the problem solving to propose in above-mentioned background technology.

For achieving the above object, the present invention provides following technical scheme:

The thermal sensitive ceramic material of a kind of low-resistivity negative temperature coefficient, includes according to the raw material of weight portion: Mn₃O₄: 30-40 Part, Co₃O₄: 35-40 part, CuO:20-25 part, La₂O₃: 10-20 part, CaO:5-10 part, MnO₂: 35-45 Part, Ni₂O₃: 30-40 part, Fe₂O₃: 0.24-0.4 part, C:0.15-0.25 part, TiO₂: 0.21-0.35 part, Cr₂O₃: 0.09-0.15 part, Nb₂O₅: 0.05-0.06 part, Nd₂O₃: 0.05-0.07 part.

The preparation method of the thermal sensitive ceramic material of described low-resistivity negative temperature coefficient, specifically comprises the following steps that

(1) first with La₂O₃、CaO、MnO₂、Ni₂O₃For raw material, by Perovskite Phase LaCaMnO Atom percentage It is placed in agate jar than weighing respectively with Spinel NiMnO atomic percentage, with water as decentralized medium, carries out Wet-milling, the time is 8h, obtains the first ball milling material；

(2) by Fe₂O₃、C、TiO₂、Cr₂O₃It is mixed to get synthetic after weighing, and presses synthetic: water: ethanol: mill Ball=1: the weight ratio ball milling 12h post-drying of 0.8: 0.6: 1.5 prepares the ball milling material of synthetic；Ball milling material is existed The warm area inside holding 120min of 800-850 DEG C synthesizes Fe₂O₃-C-TiO₂-Cr₂O₃Synthetic；

(3) synthetic is joined Mn with the percentage by weight of 1.5-5.5%₃O₄、Co₃O₄, CuO prepares compound, And by compound: water: ethanol: abrading-ball=1: the weight ratio ball milling 8-10h of 0.8: 0.6: 1.5 prepares compound ball milling material；

(4) after the compound ball milling material mixing the first ball milling material obtained in step (1) and step (3) obtained, then Add Nb₂O₅And Nd₂O₃, dry at 80-100 DEG C after mixing, then powder be sintered into phase through twice, for the first time Calcining heat is 800-900 DEG C, temperature retention time 5-7h；Calcining heat is 950-1050 DEG C for the second time, temperature retention time 6-8h； Every time after calcining under dry ball milling to 400 mesh sieves；

(5) ceramic powder after being sintered into mutually is carried out granulation, add the granulating agent of 4-6wt%；

(6) the dry-pressing formed base substrate that obtains after granulation, dry-pressing formed pressure is 250-350MPa；

(7) blank is placed in the atmosphere furnace of inert gas shielding carries out high-temperature heat treatment, described high-temperature heat treatment condition For: air velocity is 0.3-0.5L/min, heats up with temperature 5-10 DEG C/min rate of heat addition；Pre-burning at temperature 500-650 DEG C 6-10h；Constant temperature calcining 2-4h at temperature 900-1000 DEG C；Anneal at temperature 400-700 DEG C 4-12h；

(8) cooling is cooled to room temperature with stove the most naturally, obtains the thermo-sensitive material of the negative temperature coefficient of low-resistivity.

As the present invention further scheme: described granulating agent be solid content be the aqueous solution of 3-10wt%PVA or CMC.

Compared with prior art, the invention has the beneficial effects as follows:

The thermal sensitive ceramic material resistivity that the present invention obtains is low, stability is high, uniformity good, uses Perovskite Phase LaCaMnO It is combined with Spinel NiMnO two-phase, utilizes and composite pottery forms learning from other's strong points to offset one's weaknesses in phase performance, reach single The unobtainable premium properties of phase material, by adding niobium oxide and rubidium oxide, not only can be at minimal effects material constant Obtain less resistivity in the case of B value, reduce the porosity so that thermal sensitive ceramic material has more superior structural behaviour, Improve its pulse behaviors when surge current suppression occasion.

Detailed description of the invention

Below in conjunction with detailed description of the invention, the technical scheme of this patent is described in more detail.

Embodiment 1

The thermal sensitive ceramic material of a kind of low-resistivity negative temperature coefficient, includes according to the raw material of weight portion: Mn₃O₄: 30 parts, Co₃O₄: 35 parts, CuO:20 part, La₂O₃: 10 parts, CaO:5 part, MnO₂: 35 parts, Ni₂O₃: 30 parts, Fe₂O₃: 0.24 part, C:0.15 part, TiO₂: 0.21 part, Cr₂O₃: 0.09 part, Nb₂O₅: 0.05 part, Nd₂O₃: 0.05 part.

The preparation method of the thermal sensitive ceramic material of described low-resistivity negative temperature coefficient, specifically comprises the following steps that

(1) first with La₂O₃、CaO、MnO₂、Ni₂O₃For raw material, by Perovskite Phase LaCaMnO Atom percentage It is placed in agate jar than weighing respectively with Spinel NiMnO atomic percentage, with water as decentralized medium, carries out Wet-milling, the time is 8h, obtains the first ball milling material；

(2) by Fe₂O₃、C、TiO₂、Cr₂O₃It is mixed to get synthetic after weighing, and presses synthetic: water: ethanol: mill Ball=1: the weight ratio ball milling 12h post-drying of 0.8: 0.6: 1.5 prepares the ball milling material of synthetic；By ball milling material at 800 DEG C Warm area inside holding 120min synthesizes Fe₂O₃-C-TiO₂-Cr₂O₃Synthetic；

(3) synthetic is joined Mn with the percentage by weight of 1.5%₃O₄、Co₃O₄, CuO prepares compound, and By compound: water: ethanol: abrading-ball=1: the weight ratio ball milling 8h of 0.8: 0.6: 1.5 prepares compound ball milling material；

(4) after the compound ball milling material mixing the first ball milling material obtained in step (1) and step (3) obtained, then Add Nb₂O₅And Nd₂O₃, dry at 80 DEG C after mixing, then powder be sintered into phase through twice, for the first time calcining Temperature is 800 DEG C, temperature retention time 5h；Calcining heat is 950 DEG C for the second time, temperature retention time 6h；Every time through dry method after calcining It is milled under 400 mesh sieves；

(5) ceramic powder after being sintered into mutually carrying out granulation, add the granulating agent of 4wt%, described granulating agent is solid content The aqueous solution for 3wt%PVA；

(6) the dry-pressing formed base substrate that obtains after granulation, dry-pressing formed pressure is 250MPa；

(7) blank is placed in the atmosphere furnace of inert gas shielding carries out high-temperature heat treatment, described high-temperature heat treatment condition For: air velocity is 0.3L/min, heats up with the temperature 5 DEG C/min rate of heat addition；Pre-burning 6h at temperature 500 DEG C；Temperature 900 DEG C Lower constant temperature calcining 2h；Anneal at temperature 400 DEG C 4h；

(8) cooling is cooled to room temperature with stove the most naturally, obtains the thermo-sensitive material of the negative temperature coefficient of low-resistivity.

I.e. described formula is as shown in table 1:

Table 1

Is burn-on in the two sides of the thermo-sensitive material of the negative temperature coefficient of the low-resistivity obtained lead-in wire, be placed in 25 DEG C ± 0.1 DEG C and In 50 DEG C ± 0.1 DEG C thermostatic oil bath, measure its resistance value R25 and R50, and be calculated as follows resistivity of material ρ 25 and temperature Degree sensitivity coefficient B25/50:

${\mathrm{\ρ}}_{25}=\frac{R_{25}{X}_S}{L},B_{25/50}=\frac{298.15\×323.15}{25}Ln\frac{R_{25}}{R_{50}}$

Measuring and calculation result is as shown in table 2:

Table 2

Parameter	Result (100 sample statistics)
		ρ25(Ωcm)	23
P/P (%)	±3.0
		B(k)	2680
B/B (%)	±0.85
		Coefficient of stability S (%)	±2.0

Embodiment 2

The thermal sensitive ceramic material of a kind of low-resistivity negative temperature coefficient, includes according to the raw material of weight portion: Mn₃O₄: 32 parts, Co₃O₄: 36 parts, CuO:21 part, La₂O₃: 12 parts, CaO:6 part, MnO₂: 38 parts, Ni₂O₃: 32 parts, Fe₂O₃: 0.28 part, C:0.18 part, TiO₂: 0.25 part, Cr₂O₃: 0.11 part, Nb₂O₅: 0.052 part, Nd₂O₃: 0.055 part.

The preparation method of the thermal sensitive ceramic material of described low-resistivity negative temperature coefficient, specifically comprises the following steps that

(1) first with La₂O₃、CaO、MnO₂、Ni₂O₃For raw material, by Perovskite Phase LaCaMnO Atom percentage It is placed in agate jar than weighing respectively with Spinel NiMnO atomic percentage, with water as decentralized medium, carries out Wet-milling, the time is 8h, obtains the first ball milling material；

(2) by Fe₂O₃、C、TiO₂、Cr₂O₃It is mixed to get synthetic after weighing, and presses synthetic: water: ethanol: mill Ball=1: the weight ratio ball milling 12h post-drying of 0.8: 0.6: 1.5 prepares the ball milling material of synthetic；By ball milling material at 810 DEG C Warm area inside holding 120min synthesizes Fe₂O₃-C-TiO₂-Cr₂O₃Synthetic；

(3) synthetic is joined Mn with the percentage by weight of 2.5%₃O₄、Co₃O₄, CuO prepares compound, and By compound: water: ethanol: abrading-ball=1: the weight ratio ball milling 8.5h of 0.8: 0.6: 1.5 prepares compound ball milling material；

(4) after the compound ball milling material mixing the first ball milling material obtained in step (1) and step (3) obtained, then Add Nb₂O₅And Nd₂O₃, dry at 85 DEG C after mixing, then powder be sintered into phase through twice, for the first time calcining Temperature is 820 DEG C, temperature retention time 5.5h；Calcining heat is 980 DEG C for the second time, temperature retention time 6.5h；Warp after calcining every time Dry ball milling is under 400 mesh sieves；

(5) ceramic powder after being sintered into mutually carrying out granulation, add the granulating agent of 4.5wt%, described granulating agent is for admittedly to contain Amount is the aqueous solution of 5wt%PVA；

(6) the dry-pressing formed base substrate that obtains after granulation, dry-pressing formed pressure is 280MPa；

(7) blank is placed in the atmosphere furnace of inert gas shielding carries out high-temperature heat treatment, described high-temperature heat treatment condition For: air velocity is 0.35L/min, heats up with the temperature 6 DEG C/min rate of heat addition；Pre-burning 7h at temperature 530 DEG C；Temperature Constant temperature calcining 2.5h at 920 DEG C；Anneal at temperature 450 DEG C 6h；

(8) cooling is cooled to room temperature with stove the most naturally, obtains the thermo-sensitive material of the negative temperature coefficient of low-resistivity.

I.e. described formula is as shown in table 3:

Table 3

Is burn-on in the two sides of the thermo-sensitive material of the negative temperature coefficient of the low-resistivity obtained lead-in wire, be placed in 25 DEG C ± 0.1 DEG C and In 50 DEG C ± 0.1 DEG C thermostatic oil bath, measure its resistance value R25 and R50, and be calculated as follows resistivity of material ρ 25 and temperature Degree sensitivity coefficient B25/50:

${\mathrm{\ρ}}_{25}=\frac{R_{25}{X}_S}{L},B_{25/50}=\frac{298.15\×323.15}{25}Ln\frac{R_{25}}{R_{50}}$

Measuring and calculation result is as shown in table 4:

Table 4

Embodiment 3

The thermal sensitive ceramic material of a kind of low-resistivity negative temperature coefficient, includes according to the raw material of weight portion: Mn₃O₄: 35 parts, Co₃O₄: 38 parts, CuO:22 part, La₂O₃: 15 parts, CaO:8 part, MnO₂: 40 parts, Ni₂O₃: 35 parts, Fe₂O₃: 0.32 part, C:0.2 part, TiO₂: 0.28 part, Cr₂O₃: 0.12 part, Nb₂O₅: 0.055 part, Nd₂O₃: 0.06 part.

The preparation method of the thermal sensitive ceramic material of described low-resistivity negative temperature coefficient, specifically comprises the following steps that

(1) first with La₂O₃、CaO、MnO₂、Ni₂O₃For raw material, by Perovskite Phase LaCaMnO Atom percentage It is placed in agate jar than weighing respectively with Spinel NiMnO atomic percentage, with water as decentralized medium, carries out Wet-milling, the time is 8h, obtains the first ball milling material；

(2) by Fe₂O₃、C、TiO₂、Cr₂O₃It is mixed to get synthetic after weighing, and presses synthetic: water: ethanol: mill Ball=1: the weight ratio ball milling 12h post-drying of 0.8: 0.6: 1.5 prepares the ball milling material of synthetic；By ball milling material at 830 DEG C Warm area inside holding 120min synthesizes Fe₂O₃-C-TiO₂-Cr₂O₃Synthetic；

(3) synthetic is joined Mn with the percentage by weight of 3.5%₃O₄、Co₃O₄, CuO prepares compound, and By compound: water: ethanol: abrading-ball=1: the weight ratio ball milling 9h of 0.8: 0.6: 1.5 prepares compound ball milling material；

(4) after the compound ball milling material mixing the first ball milling material obtained in step (1) and step (3) obtained, then Add Nb₂O₅And Nd₂O₃, dry at 90 DEG C after mixing, then powder be sintered into phase through twice, for the first time calcining Temperature is 850 DEG C, temperature retention time 6h；Calcining heat is 1000 DEG C for the second time, temperature retention time 7h；Every time through dry after calcining Method is milled under 400 mesh sieves；

(5) ceramic powder after being sintered into mutually carrying out granulation, add the granulating agent of 5wt%, described granulating agent is solid content The aqueous solution for 10wt%PVA；

(6) the dry-pressing formed base substrate that obtains after granulation, dry-pressing formed pressure is 300MPa；

(7) blank is placed in the atmosphere furnace of inert gas shielding carries out high-temperature heat treatment, described high-temperature heat treatment condition For: air velocity is 0.4L/min, heats up with the temperature 8 DEG C/min rate of heat addition；Pre-burning 8h at temperature 590 DEG C；Temperature 950 DEG C Lower constant temperature calcining 3h；Anneal at temperature 500 DEG C 8h；

(8) cooling is cooled to room temperature with stove the most naturally, obtains the thermo-sensitive material of the negative temperature coefficient of low-resistivity.

I.e. described formula is as shown in table 5:

Table 5

Is burn-on in the two sides of the thermo-sensitive material of the negative temperature coefficient of the low-resistivity obtained lead-in wire, be placed in 25 DEG C ± 0.1 DEG C and In 50 DEG C ± 0.1 DEG C thermostatic oil bath, measure its resistance value R25 and R50, and be calculated as follows resistivity of material ρ 25 and temperature Degree sensitivity coefficient B25/50:

${\mathrm{\ρ}}_{25}=\frac{R_{25}{X}_S}{L},B_{25/50}=\frac{298.15\×323.15}{25}Ln\frac{R_{25}}{R_{50}}$

Measuring and calculation result is as shown in table 6:

Table 6

Parameter	Result (100 sample statistics)
		ρ25(Ωcm)	36
P/P (%)	±3.2
		B(k)	2790
B/B (%)	±0.91
		Coefficient of stability S (%)	±2.1

Embodiment 4

The thermal sensitive ceramic material of a kind of low-resistivity negative temperature coefficient, includes according to the raw material of weight portion: Mn₃O₄: 38 parts, Co₃O₄: 39 parts, CuO:24 part, La₂O₃: 18 parts, CaO:9 part, MnO₂: 42 parts, Ni₂O₃: 38 parts, Fe₂O₃: 0.36 part, C:0.22 part, TiO₂: 0.31 part, Cr₂O₃: 0.13 part, Nb₂O₅: 0.058 part, Nd₂O₃: 0.065 part.

The preparation method of the thermal sensitive ceramic material of described low-resistivity negative temperature coefficient, specifically comprises the following steps that

(1) first with La₂O₃、CaO、MnO₂、Ni₂O₃For raw material, by Perovskite Phase LaCaMnO Atom percentage It is placed in agate jar than weighing respectively with Spinel NiMnO atomic percentage, with water as decentralized medium, carries out Wet-milling, the time is 8h, obtains the first ball milling material；

(2) by Fe₂O₃、C、TiO₂、Cr₂O₃It is mixed to get synthetic after weighing, and presses synthetic: water: ethanol: mill Ball=1: the weight ratio ball milling 12h post-drying of 0.8: 0.6: 1.5 prepares the ball milling material of synthetic；By ball milling material at 840 DEG C Warm area inside holding 120min synthesizes Fe₂O₃-C-TiO₂-Cr₂O₃Synthetic；

(3) synthetic is joined Mn with the percentage by weight of 4.5%₃O₄、Co₃O₄, CuO prepares compound, and By compound: water: ethanol: abrading-ball=1: the weight ratio ball milling 9.5h of 0.8: 0.6: 1.5 prepares compound ball milling material；

(4) after the compound ball milling material mixing the first ball milling material obtained in step (1) and step (3) obtained, then Add Nb₂O₅And Nd₂O₃, dry at 95 DEG C after mixing, then powder be sintered into phase through twice, for the first time calcining Temperature is 880 DEG C, temperature retention time 6.5h；Calcining heat is 1020 DEG C for the second time, temperature retention time 7.5h；Warp after calcining every time Dry ball milling is under 400 mesh sieves；

(5) ceramic powder after being sintered into mutually carrying out granulation, add the granulating agent of 5.5wt%, described granulating agent is for admittedly to contain Amount is the aqueous solution of 3wt%CMC；

(6) the dry-pressing formed base substrate that obtains after granulation, dry-pressing formed pressure is 320MPa；

(7) blank is placed in the atmosphere furnace of inert gas shielding carries out high-temperature heat treatment, described high-temperature heat treatment condition For: air velocity is 0.45L/min, heats up with the temperature 8 DEG C/min rate of heat addition；Pre-burning 9h at temperature 620 DEG C；Temperature Constant temperature calcining 3.5h at 980 DEG C；Anneal at temperature 600 DEG C 10h；

(8) cooling is cooled to room temperature with stove the most naturally, obtains the thermo-sensitive material of the negative temperature coefficient of low-resistivity.

I.e. described formula is as shown in table 7:

Table 7

Is burn-on in the two sides of the thermo-sensitive material of the negative temperature coefficient of the low-resistivity obtained lead-in wire, be placed in 25 DEG C ± 0.1 DEG C and In 50 DEG C ± 0.1 DEG C thermostatic oil bath, measure its resistance value R25 and R50, and be calculated as follows resistivity of material ρ 25 and temperature Degree sensitivity coefficient B25/50:

${\mathrm{\ρ}}_{25}=\frac{R_{25}{X}_S}{L},B_{25/50}=\frac{298.15\×323.15}{25}Ln\frac{R_{25}}{R_{50}}$

Measuring and calculation result is as shown in table 8:

Table 8

Parameter	Result (100 sample statistics)
		ρ25(Ωcm)	48
P/P (%)	±3.3
		B(k)	2903
B/B (%)	±0.95
		Coefficient of stability S (%)	±2.2

Embodiment 5

The thermal sensitive ceramic material of a kind of low-resistivity negative temperature coefficient, includes according to the raw material of weight portion: Mn₃O₄: 40 parts, Co₃O₄: 40 parts, CuO:25 part, La₂O₃: 20 parts, CaO:10 part, MnO₂: 45 parts, Ni₂O₃: 40 parts, Fe₂O₃: 0.4 part, C:0.25 part, TiO₂: 0.35 part, Cr₂O₃: 0.15 part, Nb₂O₅: 0.06 part, Nd₂O₃: 0.07 Part.

The preparation method of the thermal sensitive ceramic material of described low-resistivity negative temperature coefficient, specifically comprises the following steps that

(1) first with La₂O₃、CaO、MnO₂、Ni₂O₃For raw material, by Perovskite Phase LaCaMnO Atom percentage It is placed in agate jar than weighing respectively with Spinel NiMnO atomic percentage, with water as decentralized medium, carries out Wet-milling, the time is 8h, obtains the first ball milling material；

(2) by Fe₂O₃、C、TiO₂、Cr₂O₃It is mixed to get synthetic after weighing, and presses synthetic: water: ethanol: mill Ball=1: the weight ratio ball milling 12h post-drying of 0.8: 0.6: 1.5 prepares the ball milling material of synthetic；By ball milling material at 850 DEG C Warm area inside holding 120min synthesizes Fe₂O₃-C-TiO₂-Cr₂O₃Synthetic；

(3) synthetic is joined Mn with the percentage by weight of 5.5%₃O₄、Co₃O₄, CuO prepares compound, and By compound: water: ethanol: abrading-ball=1: the weight ratio ball milling 10h of 0.8: 0.6: 1.5 prepares compound ball milling material；

(4) after the compound ball milling material mixing the first ball milling material obtained in step (1) and step (3) obtained, then Add Nb₂O₅And Nd₂O₃, dry at 100 DEG C after mixing, then powder be sintered into phase through twice, forge for the first time Burning temperature is 900 DEG C, temperature retention time 7h；Calcining heat is 1050 DEG C for the second time, temperature retention time 8h；Warp after calcining every time Dry ball milling is under 400 mesh sieves；

(5) ceramic powder after being sintered into mutually carrying out granulation, add the granulating agent of 6wt%, described granulating agent is solid content The aqueous solution for 10wt%CMC；

(6) the dry-pressing formed base substrate that obtains after granulation, dry-pressing formed pressure is 350MPa；

(7) blank is placed in the atmosphere furnace of inert gas shielding carries out high-temperature heat treatment, described high-temperature heat treatment condition For: air velocity is 0.5L/min, heats up with the temperature 10 DEG C/min rate of heat addition；Pre-burning 10h at temperature 650 DEG C；Temperature Constant temperature calcining 4h at 1000 DEG C；Anneal at temperature 700 DEG C 12h；

(8) cooling is cooled to room temperature with stove the most naturally, obtains the thermo-sensitive material of the negative temperature coefficient of low-resistivity.

I.e. described formula is as shown in table 9:

Table 9

Is burn-on in the two sides of the thermo-sensitive material of the negative temperature coefficient of the low-resistivity obtained lead-in wire, be placed in 25 DEG C ± 0.1 DEG C and In 50 DEG C ± 0.1 DEG C thermostatic oil bath, measure its resistance value R25 and R50, and be calculated as follows resistivity of material ρ 25 and temperature Degree sensitivity coefficient B25/50:

${\mathrm{\ρ}}_{25}=\frac{R_{25}{X}_S}{L},B_{25/50}=\frac{298.15\×323.15}{25}Ln\frac{R_{25}}{R_{50}}$

Measuring and calculation result is as shown in table 10:

Table 10

Parameter	Result (100 sample statistics)
		ρ25(Ωcm)	55
P/P (%)	±3.4
		B(k)	2954
B/B (%)	±1.0
		Coefficient of stability S (%)	±2.3

Being shown by the result of described embodiment 1-5, the thermo-sensitive material resistivity that the present invention makes is 23 Ω cm-55 Ω cm, B

25/50=2680K-2954K, within the error of resistivity is ± 4%, the error of B value is ± 1%, and this material is special It is not suitable as surge current absorption function type thermistor, and material cost is less than 1/2nd of conventional formulation material cost.

The thermal sensitive ceramic material resistivity that the present invention obtains is low, stability is high, uniformity good, uses Perovskite Phase LaCaMnO It is combined with Spinel NiMnO two-phase, utilizes and composite pottery forms learning from other's strong points to offset one's weaknesses in phase performance, reach single The unobtainable premium properties of phase material, by adding niobium oxide and rubidium oxide, not only can be at minimal effects material constant Obtain less resistivity in the case of B value, reduce the porosity so that thermal sensitive ceramic material has more superior structural behaviour, Improve its pulse behaviors when surge current suppression occasion.

Above the better embodiment of this patent is explained in detail, but this patent is not limited to above-mentioned embodiment, In the ken that those of ordinary skill in the art is possessed, it is also possible to make each on the premise of without departing from this patent objective Plant change.

Claims (3)

1. the thermal sensitive ceramic material of a low-resistivity negative temperature coefficient, it is characterised in that include according to the raw material of weight portion: Mn₃O₄: 30-40 part, Co₃O₄: 35-40 part, CuO:20-25 part, La₂O₃: 10-20 part, CaO:5-10 part, MnO₂: 35-45 part, Ni₂O₃: 30-40 part, Fe₂O₃: 0.24-0.4 part, C:0.15-0.25 part, TiO₂: 0.21-0.35 Part, Cr₂O₃: 0.09-0.15 part, Nb₂O₅: 0.05-0.06 part, Nd₂O₃: 0.05-0.07 part.

2. a preparation method for the thermal sensitive ceramic material of low-resistivity negative temperature coefficient as claimed in claim 1, its feature It is, specifically comprises the following steps that

(1) first with La₂O₃、CaO、MnO₂、Ni₂O₃For raw material, by Perovskite Phase LaCaMnO Atom percentage It is placed in agate jar than weighing respectively with Spinel NiMnO atomic percentage, with water as decentralized medium, carries out Wet-milling, the time is 8h, obtains the first ball milling material；

(2) by Fe₂O₃、C、TiO₂、Cr₂O₃It is mixed to get synthetic after weighing, and presses synthetic: water: ethanol: mill Ball=1: the weight ratio ball milling 12h post-drying of 0.8: 0.6: 1.5 prepares the ball milling material of synthetic；Ball milling material is existed The warm area inside holding 120min of 800-850 DEG C synthesizes Fe₂O₃-C-TiO₂-Cr₂O₃Synthetic；

(3) synthetic is joined Mn with the percentage by weight of 1.5-5.5%₃O₄、Co₃O₄, CuO prepares compound, And by compound: water: ethanol: abrading-ball=1: the weight ratio ball milling 8-10h of 0.8: 0.6: 1.5 prepares compound ball milling material；

(4) after the compound ball milling material mixing the first ball milling material obtained in step (1) and step (3) obtained, then Add Nb₂O₅And Nd₂O₃, dry at 80-100 DEG C after mixing, then powder be sintered into phase through twice, for the first time Calcining heat is 800-900 DEG C, temperature retention time 5-7h；Calcining heat is 950-1050 DEG C for the second time, temperature retention time 6-8h； Every time after calcining under dry ball milling to 400 mesh sieves；

(5) ceramic powder after being sintered into mutually is carried out granulation, add the granulating agent of 4-6wt%；

(6) the dry-pressing formed base substrate that obtains after granulation, dry-pressing formed pressure is 250-350MPa；

(7) blank is placed in the atmosphere furnace of inert gas shielding carries out high-temperature heat treatment, described high-temperature heat treatment condition For: air velocity is 0.3-0.5L/min, heats up with temperature 5-10 DEG C/min rate of heat addition；Pre-burning at temperature 500-650 DEG C 6-10h；Constant temperature calcining 2-4h at temperature 900-1000 DEG C；Anneal at temperature 400-700 DEG C 4-12h；

(8) cooling is cooled to room temperature with stove the most naturally, obtains the thermo-sensitive material of the negative temperature coefficient of low-resistivity.

The preparation method of the thermal sensitive ceramic material of low-resistivity negative temperature coefficient the most according to claim 2, its feature exists In, described granulating agent be solid content be the aqueous solution of 3-10wt%PVA or CMC.