Multi-component NTC (Negative Temperature Coefficient) thermistor ceramic material, preparation method and thermistor element

Abstract

The invention discloses a multi-component NTC (Negative Temperature Coefficient) thermistor ceramic material, a preparation method and a thermistor element, the chemical formula of the multi-component NTC thermistor ceramic material is ZnTi (0.8-x) CuxB (0.2) Fe (0.5) Mn (0.5) O4, non-magnetic elements Cr, Mn and Zn are adopted as main bodies, and copper oxide is added to reduce the normal-temperature resistance of a thermistor. The copper oxide can greatly improve the concentration of conductive ions in the thermistor, so that the normal-temperature resistance and the material constant B value of the thermistor are reduced, and meanwhile, the stability of the thermistor is reduced by adding the copper oxide, so that the resistance of the thermistor drifts seriously at high temperature. The titanium oxide can improve the thermal stability and B value of the thermistor, and can inhibit the growth of crystal grains in the sintering process of the thermistor, thereby improving the electrical stability of the thermistor. And the thermistor with proper resistance value and B value is obtained by adjusting the contents of Ti and Cu. The liquid phase sintering of the thermistor is realized by adding boron oxide, the sintering temperature is reduced under the condition that the electrical property of the thermistor is not influenced, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic materials and electronic components, and in particular to a multi-component NTC thermistor ceramic material, a preparation method and a thermistor element. Background Art

[0002] NTC thermistor is an important component in the field of temperature sensor. It has the advantages of high temperature measurement accuracy, low cost and small size. It is widely used in temperature measurement, temperature control and surge current suppression.

[0003] NTC thermistors generally use transition metal oxides with a spinel structure. It is generally believed that the conductivity of NTC thermistors is neither the result of the movement of electrons in the conduction band nor the migration of holes in the valence band, but the result of direct transfer and transition of electrons between energy levels, and the result of electrons jumping from one atom to another adjacent atomic position. Therefore, the distribution of cations has an impact on the conductivity of the thermistor. Studies have shown that the cations in the thermistor crystal cause lattice distortion and increase the elastic energy of the lattice. In order to eliminate or reduce the elastic energy in the lattice, the cations tend to be oriented and clustered. During the preparation of the thermistor, high temperature will break this oriented and clustered state, and retain this non-equilibrium state during cooling. However, this non-equilibrium state will evolve to an equilibrium state during use, which will cause changes in the distribution of cations, drift in the resistance of the thermistor, and finally lead to problems such as high resistance value, large self-heating during temperature measurement, and affect the temperature measurement accuracy. At the same time, existing thermistors generally contain magnetic elements such as Ni, Fe, and Co, which limits their use in certain magnetic environments.

[0004] Therefore, those skilled in the art are committed to developing a multi-component NTC thermistor ceramic material, a preparation method and a thermistor element with low resistance value, low self-heating and high temperature measurement accuracy. Summary of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a multi-component NTC thermistor ceramic material, a preparation method and a thermistor element with low resistance value, low self-heating and high temperature measurement accuracy.

[0006] To achieve the above-mentioned invention object, the present invention provides a multi-component NTC thermistor ceramic material, the chemical formula of which is ZnTi 0.8-x Cu x B 0.2 Fe 0.5 Mn 0.5 O4.

[0007] Furthermore, the value of x in the chemical composition of the thermistor ceramic material is 0.4 to 0.8.

[0008] The present invention also provides a method for preparing a multi-component NTC thermistor ceramic material, comprising the following steps:

[0009] S1. Prepare a first mixed powder: Weigh oxides of Zn, Ti, Cu and Fe and manganese carbonate or manganese oxide according to the above ratio and place them in a planetary ball mill for wet ball milling, and dry the milled slurry to obtain a first mixed powder;

[0010] S2. Preparation of pre-fired material: The first mixed powder is placed in a muffle furnace and pre-fired and then cooled with the furnace to obtain a pre-fired material;

[0011] S3 preparation of sieving pre-burned material: the pre-burned material was placed in a planetary ball mill for dry milling, and then sieved with a 300 mesh sample sieve to obtain sieving pre-burned material;

[0012] S4. Prepare a second mixed powder: weigh the sieved pre-sintered material and the boron compound, place it in a planetary ball mill for wet ball milling, and dry the milled slurry to obtain a second mixed powder;

[0013] S5. Preparation of ceramic green body: placing the second mixed powder into a mold and isostatically pressing to obtain a ceramic green body;

[0014] S6. Producing finished material: placing the ceramic green body into a muffle furnace and sintering it to obtain the multi-component NTC thermistor ceramic material.

[0015] Furthermore, in step S1, the ball milling medium is alcohol, the ball milling beads are made of zirconium oxide, the rotation speed of the planetary ball mill is 120 rpm to 150 rpm, the ball milling is performed for 3 h to 4 h, and the slurry after ball milling is dried at 80 to 100° C. to obtain the first mixed powder.

[0016] Furthermore, in step S2, the first mixed powder is placed in a muffle furnace and pre-fired at 1000°C to 1100°C for 2 hours, and then cooled in the furnace to obtain a pre-fired material.

[0017] Furthermore, in step S3, the pre-burned material is put into a planetary ball mill for dry ball milling for 1 h to 2 h at a rotation speed of 120 rpm to 150 rpm, and then sieved with a 300-mesh sample sieve to obtain a sieved pre-burned material.

[0018] Furthermore, in step S4, the boron compound is boric oxide or boric acid, the ball milling medium is alcohol, the ball milling beads are made of zirconium oxide, the rotation speed of the planetary ball mill is 120rpm~150rpm, the ball milling is 3h~4h, and the slurry after ball milling is dried at 80~100°C with a rotary dryer to obtain the second mixed powder.

[0019] Furthermore, in step S5, the second mixed powder is placed in a mold for isostatic pressing with a molding pressure of 200 MPa and a holding time of 30 minutes to obtain a ceramic green body.

[0020] Furthermore, in step S6, the ceramic green body is placed in a muffle furnace for sintering, the sintering atmosphere is air, the sintering temperature is 1100° C. to 1200° C., the sintering time is 3 hours, and the heating rate is 5° C. / min.

[0021] The present invention also provides a multi-component NTC thermistor element, which is made of the multi-component NTC thermistor ceramic material. First, the multi-component NTC thermistor ceramic material is sliced ​​according to a required thickness to obtain a thermistor sheet, electrodes are prepared on the upper and lower surfaces of the thermistor sheet respectively, and finally the thermistor element is obtained by dicing and cutting according to a required size.

[0022] Compared with the prior art, the advantages of the present invention include: the present invention adopts non-magnetic elements Cr, Mn, and Zn as the main body of the multi-component NTC thermistor ceramic material, and reduces the room temperature resistance of the thermistor by adding copper oxide. Since copper oxide can greatly increase the concentration of conductive ions in the thermistor, the room temperature resistance and material constant B value of the thermistor are reduced, but at the same time, the addition of copper oxide will reduce the stability of the thermistor, causing the resistance drift of the thermistor to be serious at high temperatures. Titanium oxide can improve the thermal stability and B value of the thermistor. Titanium oxide can inhibit the growth of grains during the sintering process of the thermistor, thereby improving the electrical stability of the thermistor. By adjusting the content of Ti and Cu, a thermistor with suitable resistance value and B value is obtained, and the lowest resistance value is 1634Ω·cm after testing. Liquid phase sintering of the thermistor is achieved by adding boron oxide, and its sintering temperature is reduced without affecting the electrical properties of the thermistor, thereby reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention is a flow chart for preparing the multi-component NTC thermistor ceramic material;

[0024] Figure 2 The figure is a flow chart of the preparation of the multi-component NTC thermistor element of the present invention. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to understand the characteristics and effects of the present application, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein have the common meanings understood by those skilled in the art for the present application. In case of conflict, the definitions in this specification shall prevail.

[0026] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present application in any way, that is, the content of the present application can be implemented without being limited by any specific theory or mechanism.

[0027] As used herein, "this application" means "the present invention" or "the present disclosure".

[0028] The use of "one", "an", "a kind" or similar expressions to describe the components and technical features described in this application is merely for the convenience of expression and to provide a general meaning to the scope of this application. Therefore, such description should be understood to include one or at least one, and the singular also includes the plural, unless it is obvious that it refers to another meaning.

[0029] In this document, "or its combination" means "or any combination thereof", and "any one", "any one" means "any one", "any one" or "any one".

[0030] As used herein, the terms "comprises," "including," "having," "containing," or any other similar terms are open-ended transitional phrases that are intended to cover non-exclusive inclusions. For example, a composition or article containing multiple elements is not limited to the elements listed herein, but may also include other elements that are not explicitly listed but are generally inherent to the composition or article. In addition, unless otherwise expressly stated, the term "or" refers to an inclusive "or" rather than an exclusive "or." For example, any of the following situations satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and both A and B are true (or exist). In addition, in this article, the terms "comprising", "including", "having", and "containing" should be interpreted as being specifically disclosed and simultaneously covering closed conjunctions such as "consisting of", "consisting of", and "the remainder is", as well as conjunctions such as "consisting essentially of", "mainly consisting of", "mainly consisting of", "basically containing", "essentially consisting of", "essentially consisting of", and "essentially containing".

[0031] In this article, all features or conditions such as numerical values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are only for simplicity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be deemed to have covered and specifically disclosed all possible sub-ranges and individual values ​​within the range (including integers and fractions), especially integer values. For example, the range description of "1.0 to 8.0" or "between 1.0 and 8.0" or "between 1.0 and 8.0" should be deemed to have specifically disclosed all sub-ranges such as 1.0 to 8.0, 1.0 to 7.0, 2.0 to 8.0, 2.0 to 6.0, 3.0 to 6.0, 4.0 to 8.0, 3.0 to 8.0, etc., and should be deemed to cover endpoint values, especially sub-ranges defined by integer values, and should be deemed to have specifically disclosed individual values ​​such as 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, etc. Unless otherwise indicated, the foregoing method of interpretation applies to all contents of the entire application, regardless of whether the scope is broad or not.

[0032] If the quantity, concentration or other numerical value or parameter is expressed as a range, a preferred range (or a better range) or a series of upper and lower limits, it should be understood that all ranges consisting of any pair of the upper limit or preferred value (or a better value) of the range and the lower limit or preferred value (or a better value) of the range have been specifically disclosed herein, regardless of whether these ranges are disclosed separately. In addition, if a numerical range is mentioned herein, unless otherwise specified, the range should include its endpoints and all integers and fractions within the range.

[0033] In this document, numerical values ​​should be understood to have the accuracy of the number of significant digits of the numerical value, provided that the purpose of the invention can be achieved. For example, the number 40.0 should be understood to cover the range of 39.50 to 40.49.

[0034] It should be understood that the features disclosed in the various embodiments herein may be arbitrarily combined to form the technical solution of the present application, as long as there is no contradiction in the combination of these features.

[0035] The present application will be described below with specific implementations and examples. It should be understood that these specific implementations and examples are merely illustrative and are not intended to limit the scope of the present application and its use.

[0036] Unless otherwise specified, the methods, reagents and conditions used in the preparation examples, comparative examples and embodiments below are conventional methods, reagents and conditions in the art. The instrument used in the thermistor test is the Jinke JK2515 thermistor tester produced by Changzhou Jinai Lian Electronic Technology Co., Ltd.

[0037] Example 1

[0038] A multi-component NTC thermistor element, the multi-component NTC thermistor ceramic material chemical formula of which is ZnTi 0.4 Cu 0.4 B 0.2 Fe 0.5 Mn 0.5 O4, the preparation method comprises the following steps:

[0039] S1. Prepare the first mixed powder: weigh 81.4 g zinc oxide, 32 g titanium oxide, 31.8 g copper oxide, 38 g chromium oxide, and 57.5 g manganese carbonate, and put them into a planetary ball mill for wet ball milling. The ball milling medium is alcohol, the ball milling beads are made of zirconium oxide, the speed is 120 rpm, the ball milling is 4 h, and the slurry after ball milling is dried at 80 ° C to obtain a first mixed powder;

[0040] S2. Preparation of pre-burned material: The first mixed powder was placed in a muffle furnace and pre-burned at 1200 ° C for 2h, and the pre-burned material was obtained by cooling the furnace;

[0041] S3 preparation of sieving pre-burned material: the pre-burned material was placed in a planetary ball mill for dry milling for 2h at a speed of 120rpm, and then sieved with a 300-mesh sample sieve to obtain sieving pre-burned material;

[0042] S4. Preparation of a second mixed powder: Weigh 12.37 g of boric acid, 214.53 g of sieved pre-sintered material, and mix them in a planetary ball mill for wet ball milling. The milling medium is alcohol, the ball milling beads are made of zirconium oxide, the speed of the planetary ball mill is 120 rpm, and the ball milling is performed for 3 h. The slurry after ball milling is dried at 80 ° C with a rotary dryer to obtain the second mixed powder;

[0043] S5. Preparation of ceramic green body: The second mixed powder was placed in a mold and isostatically pressed at a molding pressure of 200Mpa and a holding time of 30min to obtain a ceramic green body;

[0044] S6. Prepare finished material: put the ceramic green body into a muffle furnace for sintering, the sintering atmosphere is air, the sintering temperature is 1200°C, the sintering time is 3h, the heating rate is 5°C / min, and the multi-component NTC thermistor ceramic material is obtained;

[0045] S7. Slicing: Slicing the multi-component NTC thermistor ceramic material to a thickness of 0.5 mm to obtain a thermistor sheet;

[0046] S8. Preparing electrodes: Preparing silver electrodes on the upper and lower surfaces of the thermistor sheet;

[0047] S9. Slicing: Slice the thermistor sheet with silver electrodes into a size of 1.5 mm×1.5 mm to obtain thermistor elements.

[0048] Example 2

[0049] A multi-component NTC thermistor element, the multi-component NTC thermistor ceramic material chemical formula of which is ZnTi 0.3 Cu 0.5 B 0.2 Fe 0.5 Mn 0.5 O4, the preparation method comprises the following steps:

[0050] S1. Prepare the first mixed powder: weigh 162.8g zinc oxide, 48g titanium oxide, 79.5g copper oxide, 76g chromium oxide, and 70.94g manganese oxide, and put them into a planetary ball mill for wet ball milling. The ball milling medium is alcohol, the ball milling beads are made of zirconium oxide, the speed is 150rpm, and the ball milling is performed for 4h. The slurry after ball milling is dried at 80°C to obtain a first mixed powder;

[0051] S2. Preparation of pre-burned material: The first mixed powder was placed in a muffle furnace and pre-burned at 1200 ° C for 2h, and the pre-burned material was obtained by cooling the furnace;

[0052] S3 preparation of sieving pre-burned material: the pre-burned material was placed in a planetary ball mill for dry milling for 2h at a speed of 150rpm, and then sieved with a 300-mesh sample sieve to obtain sieving pre-burned material;

[0053] S4. Preparation of a second mixed powder: Weigh 24.73 g of boric acid and 432.2 g of pre-sintered material and mix them in a planetary ball mill for wet ball milling. The milling medium is alcohol, the ball milling beads are made of zirconium oxide, the speed of the planetary ball mill is 150 rpm, and the ball milling is performed for 3 h. The slurry after ball milling is dried at 80 ° C with a rotary dryer to obtain the second mixed powder;

[0054] S5. Preparation of ceramic green body: The second mixed powder was placed in a mold and isostatically pressed at a molding pressure of 200Mpa and a holding time of 30min to obtain a ceramic green body;

[0055] S6. Prepare finished material: put the ceramic green body into a muffle furnace for sintering, the sintering atmosphere is air, the sintering temperature is 1200°C, the sintering time is 3h, the heating rate is 5°C / min, and the multi-component NTC thermistor ceramic material is obtained;

[0056] S7. Slicing: Slicing the multi-component NTC thermistor ceramic material to a thickness of 0.5 mm to obtain a thermistor sheet;

[0057] S8. Preparing electrodes: Preparing silver electrodes on the upper and lower surfaces of the thermistor sheet;

[0058] S9. Slicing: Slice the thermistor sheet with silver electrodes into a size of 1.5 mm×1.5 mm to obtain thermistor elements.

[0059] Example 3

[0060] A multi-component NTC thermistor element, the multi-component NTC thermistor ceramic material chemical formula of which is ZnTi 0.2 Cu 0.6 B 0.2 Fe 0.5 Mn 0.5 O4, the preparation method comprises the following steps:

[0061] S1. Prepare the first mixed powder: weigh 81.4 g zinc oxide, 16 g titanium oxide, 47.7 g copper oxide, 38 g chromium oxide and 57.5 g manganese carbonate, put them into a planetary ball mill for wet ball milling, the ball milling medium is alcohol, the ball milling beads are made of zirconium oxide, the speed is 150 rpm, the ball milling is for 4 h, and the slurry after ball milling is dried at 80 ° C to obtain a first mixed powder;

[0062] S2. Preparation of pre-burned material: The first mixed powder was placed in a muffle furnace and pre-burned at 1150 ° C for 2h, and the pre-burned material was obtained by cooling the furnace;

[0063] S3 preparation of sieving pre-burned material: the pre-burned material was placed in a planetary ball mill for dry milling for 2h at a speed of 120rpm, and then sieved with a 300-mesh sample sieve to obtain sieving pre-burned material;

[0064] S4. Preparation of a second mixed powder: Weigh 6.96 g of boron oxide, 217.66 g of pre-sintered material, and mix them in a planetary ball mill for wet ball milling. The milling medium is alcohol, and the ball milling beads are made of zirconium oxide. The speed of the planetary ball mill is 120 rpm. The ball milling is performed for 3 h. The slurry after ball milling is dried at 80 ° C with a rotary dryer to obtain the second mixed powder;

[0065] S5. Preparation of ceramic green body: The second mixed powder was placed in a mold and isostatically pressed at a molding pressure of 200Mpa and a holding time of 30min to obtain a ceramic green body;

[0066] S6. Prepare finished material: put the ceramic green body into a muffle furnace for sintering, the sintering atmosphere is air, the sintering temperature is 1150°C, the sintering time is 3h, the heating rate is 5°C / min, and the multi-component NTC thermistor ceramic material is obtained;

[0067] S7. Slicing: Slicing the multi-component NTC thermistor ceramic material to a thickness of 0.5 mm to obtain a thermistor sheet;

[0068] S8. Preparing electrodes: Preparing silver electrodes on the upper and lower surfaces of the thermistor sheet;

[0069] S9. Slicing: Slice the thermistor sheet with silver electrodes into a size of 1.5 mm×1.5 mm to obtain thermistor elements.

[0070] Example 4

[0071] A multi-component NTC thermistor element, the multi-component NTC thermistor ceramic material chemical formula of which is ZnTi 0.1 Cu 0.7 B 0.2 Fe 0.5 Mn 0.5 O4, the preparation method comprises the following steps:

[0072] S1. Prepare the first mixed powder: weigh 81.4 g of zinc oxide, 8 g of titanium oxide, 55.65 g of copper oxide, 38 g of chromium oxide and 57.5 g of manganese carbonate, and put them into a planetary ball mill for wet ball milling. The ball milling medium is alcohol, the ball milling beads are made of zirconium oxide, the speed is 120 rpm, and the ball milling is performed for 3.5 h. The slurry after ball milling is dried at 100 ° C to obtain a first mixed powder;

[0073] S2. Preparation of pre-burned material: The first mixed powder was placed in a muffle furnace and pre-burned at 1000 ° C for 4h, and the pre-burned material was obtained by cooling the furnace;

[0074] S3 preparation of sieving pre-burned material: the pre-burned material was placed in a planetary ball mill for dry milling for 2h at a speed of 120rpm, and then sieved with a 300-mesh sample sieve to obtain sieving pre-burned material;

[0075] S4. Preparation of a second mixed powder: Weigh 12.37 g of boric acid and 219.23 g of pre-sintered material and mix them in a planetary ball mill for wet ball milling. The milling medium is alcohol, the ball milling beads are made of zirconium oxide, the speed of the planetary ball mill is 150 rpm, and the ball milling is performed for 3 h. The slurry after ball milling is dried at 100 ° C with a rotary dryer to obtain the second mixed powder;

[0076] S5. Preparation of ceramic green body: The second mixed powder was placed in a mold and isostatically pressed at a molding pressure of 200Mpa and a holding time of 30min to obtain a ceramic green body;

[0077] S6. Prepare finished material: put the ceramic green body into a muffle furnace for sintering, the sintering atmosphere is air, the sintering temperature is 1100°C, the sintering time is 3h, the heating rate is 5°C / min, and the multi-component NTC thermistor ceramic material is obtained;

[0078] S7. Slicing: Slicing the multi-component NTC thermistor ceramic material to a thickness of 0.5 mm to obtain a thermistor sheet;

[0079] S8. Preparing electrodes: Preparing silver electrodes on the upper and lower surfaces of the thermistor sheet;

[0080] S9. Slicing: Slice the thermistor sheet with silver electrodes into a size of 1.5 mm×1.5 mm to obtain thermistor elements.

[0081] Example 5

[0082] A multi-component NTC thermistor element, the multi-component NTC thermistor ceramic material chemical formula of which is ZnCu 0.8 B 0.2 Fe 0.5 Mn 0.5 O4, the preparation method comprises the following steps:

[0083] S1. Prepare the first mixed powder: weigh 81.4 g zinc oxide, 63.6 g copper oxide, 38 g chromium oxide and 57.5 g manganese carbonate, put them into a planetary ball mill for wet ball milling, the ball milling medium is alcohol, the ball milling beads are made of zirconium oxide, the speed is 150 rpm, the ball milling is for 3 h, and the slurry after ball milling is dried at 90 ° C to obtain a first mixed powder;

[0084] S2. Preparation of pre-burned material: The first mixed powder was placed in a muffle furnace and pre-burned at 1100 ° C for 2h, and the pre-burned material was obtained by cooling the furnace;

[0085] S3 preparation of sieving pre-burned material: the pre-burned material was placed in a planetary ball mill for dry milling for 2h at a speed of 120rpm, and then sieved with a 300-mesh sample sieve to obtain sieving pre-burned material;

[0086] S4. Preparation of a second mixed powder: Weigh 12.37 g of boric acid and 220.8 g of pre-sintered material and mix them in a planetary ball mill for wet ball milling. The milling medium is alcohol, the ball milling beads are made of zirconium oxide, the speed of the planetary ball mill is 130 rpm, and the ball milling is performed for 3 h. The slurry after ball milling is dried at 90 ° C with a rotary dryer to obtain the second mixed powder;

[0087] S5. Preparation of ceramic green body: The second mixed powder was placed in a mold and isostatically pressed at a molding pressure of 200Mpa and a holding time of 30min to obtain a ceramic green body;

[0088] S6. Prepare finished material: put the ceramic green body into a muffle furnace for sintering, the sintering atmosphere is air, the sintering temperature is 1100°C, the sintering time is 3h, the heating rate is 5°C / min, and the multi-component NTC thermistor ceramic material is obtained;

[0089] S7. Slicing: Slicing the multi-component NTC thermistor ceramic material to a thickness of 0.5 mm to obtain a thermistor sheet;

[0090] S8. Preparing electrodes: Preparing silver electrodes on the upper and lower surfaces of the thermistor sheet;

[0091] S9. Slicing: Slice the thermistor sheet with silver electrodes into a size of 1.5 mm×1.5 mm to obtain thermistor elements.

[0092] The above embodiments were tested, and the resistance values ​​of thermistor elements of embodiments 1 to 5 at 25°C and 85°C were obtained by formula B. 25 / 85 =[(T 25 ×T 85 ) / (T 85 -T 25 )]×ln(R 25 / R 85 ) Calculate the thermistor material constant B 25 / 85 .

[0093] The thermistor is placed in a 125℃ oven and kept warm for 1000 hours for aging test. The change in the resistance value of the thermistor at 25℃ before and after the aging test, ΔR, is calculated. 25 Investigate the stability of thermistor, where ΔR 25 =(R 25老化前 -R 25老化后 ) / R 25老化前 ×100%. The results are shown in Table 1:

[0094] Table 1 Electrical performance parameters of thermistors in Examples 1 to 5

[0095]

[0096]

[0097] It can be seen from Table 1 that from Examples 1 to 5, as the Cu content increases, the room temperature resistance of the thermistor gradually decreases, and the lowest resistance value is 1634Ω·cm.

[0098] From Examples 1 to 5, as the Ti content increases, the B value of the thermistor gradually increases, and the resistance change rate after the 1000h aging test gradually decreases. The addition of Ti is beneficial to improving the sensitivity and stability of the thermistor.

[0099] The multi-component NTC thermistor ceramic material of the present invention has the advantages of low room temperature resistance and good stability. Compared with conventional thermistors, the thermistor material of the present invention has no magnetism. The nominal resistance, material constant B value and other performance parameters of the thermistor can be adjusted by adjusting the content of Ti and Cu. At the same time, the present invention has a low sintering temperature, is simple to prepare, and the raw materials used do not contain high-priced raw materials such as Ni and Co, so the production cost is low.

[0100] It should be understood that the above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly. It cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, some simple deductions or substitutions can be made without departing from the concept of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A multi-component NTC thermistor ceramic material, characterized in that: The chemical formula of the thermistor ceramic material is ZnTi 0.8-x Cu x B 0.2 Fe 0.5 Mn 0.5 O4.

2. The multi-component NTC thermistor ceramic material according to claim 1, characterized in that: The value of x in the chemical composition of the thermistor ceramic material is 0.4 to 0.

8.

3. A method for preparing the multi-component NTC thermistor ceramic material according to claim 1 or 2, characterized in that: The following steps are involved: S1. Preparation of a first mixed powder: Weighing oxides of Zn, Ti, Cu and Fe and manganese carbonate according to claim 1 or 2, wet ball milling, and drying to obtain a first mixed powder; S2. Preparing a pre-burned material: The first mixed powder is pre-burned and then cooled in the furnace to obtain a pre-burned material; S3. Preparation of sieved pre-burned material: dry ball milling the pre-burned material, and then sieving to obtain sieved pre-burned material; S4. Preparing a second mixed powder: weighing the sieved pre-sintered material and the boron compound, wet ball milling, and then drying to obtain a second mixed powder; S5. Preparation of ceramic green body: isostatically pressing the second mixed powder to obtain a ceramic green body; S6. Producing finished material: sintering the ceramic green body to obtain the multi-component NTC thermistor ceramic material.

4. The method for preparing the multi-component NTC thermistor ceramic material according to claim 3, characterized in that: In step S1, the ball milling medium is alcohol, the ball milling beads are made of zirconium oxide, the rotation speed of the planetary ball mill is 120 rpm to 150 rpm, the ball milling is performed for 3 h to 4 h, and the slurry after ball milling is dried at 80 to 100° C. to obtain the first mixed powder.

5. The method for preparing the multi-component NTC thermistor ceramic material according to claim 3, characterized in that: In step S2, the first mixed powder is pre-sintered at 1000°C to 1200°C for 2 hours and cooled in the furnace to obtain a pre-sintered material.

6. The method for preparing the multi-component NTC thermistor ceramic material according to claim 3, characterized in that: In step S3, the pre-burned material is dry-milled for 1 h to 2 h at a rotation speed of 120 rpm to 150 rpm, and then sieved with a 300-mesh sieve to obtain a sieved pre-burned material.

7. The method for preparing the multi-component NTC thermistor ceramic material according to claim 3, characterized in that: In step S4, the boron compound is boric oxide or boric acid, the ball milling medium is alcohol, the ball milling beads are made of zirconium oxide, the ball milling speed is 120rpm~150rpm, the ball milling is 3h~4h, and the slurry after ball milling is dried at 80~100°C to obtain the second mixed powder.

8. The method for preparing the multi-component NTC thermistor ceramic material according to claim 3, characterized in that: In step S5, the isostatic pressing pressure is 200 MPa, and the holding time is 30 min to obtain a ceramic green body.

9. The method for preparing the multi-component NTC thermistor ceramic material according to claim 3, characterized in that: In step S6, the sintering atmosphere is air, the sintering temperature is 1100°C to 1200°C, the sintering time is 3 hours, and the heating rate is 5°C / min.

10. A multi-component NTC thermistor element, characterized in that: The multi-component NTC thermistor ceramic material according to claim 1 or 2 is used for manufacturing. First, the multi-component NTC thermistor ceramic material is sliced ​​according to the required thickness to obtain a thermistor sheet, electrodes are prepared on the upper and lower surfaces of the thermistor sheet respectively, and finally the thermistor element is obtained by dicing and cutting according to the required size.

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