KR101538108B1 - Compositie for temperature sensor increased high-temperature resistance and tprocess for producing same - Google Patents

Abstract

The present invention relates to a composition for a temperature sensor having high-temperature resistance and a method for manufacturing the same. The present invention is installed in a combustion engine and a connection component of the combustion engine to be capable of sensing temperature. The composition for a temperature sensor is capable of easily measuring the temperature in the low temperature and the high temperature. According to the present invention, the composition for a temperature sensor more easily controls resistance of the temperature in accordance with a change in the temperature in order to secure stability of a resistance value and a proper resistance range in the high temperature and having the resistance value of 90 Ω at the temperature of 900 degrees Cesius and having the resistance value of 0.9 MΩ at the temperature of 40 degrees Celsius below zero so as to easily measure the temperature although there is the change in the temperature in the low temperature and the high temperature.

Description

TECHNICAL FIELD [0001] The present invention relates to a composition for a temperature sensor having a high temperature resistance and a method for producing the same,

TECHNICAL FIELD The present invention relates to a composition for a temperature sensor, which is installed in a combustion engine and its connecting parts to detect a temperature, and a method for manufacturing the composition, and more particularly, to a composition for a temperature sensor showing a property of easily measuring a temperature even at a low temperature and a high temperature .

As fossil fuels such as gasoline, diesel, kerosene, LNG, and LPG are depleted, the value of fossil fuels is soaring that it is urgently required to develop a technology capable of improving the combustion efficiency of the above fuels. In addition, development of various devices capable of reducing harmful gas generated when fossil fuel is burned is also demanded by strengthening environmental standards. One such technique is a temperature sensor installed in an exhaust apparatus of an automobile. Particularly, in the case of diesel cars, regulation of dusts and NOx generated in combustion is further strengthened, so that it is almost necessary to mount an exhaust device capable of re-burning such harmful gas or converting it into harmless gas. Since the temperature sensor used in the exhaust system basically needs to exhibit the optimum efficiency even in a high temperature environment of 500 캜 or more, it is required to have high precision and high durability. Also, it is necessary to measure within the temperature range of 0 ° C - 900 ° C because the temperature difference depending on the time of driving the car, ie day and season, and the region, is large.

In general, temperature sensors are manufactured using metal or metal oxides. Temperature sensors used in high temperature environments are mainly made of metal oxides. Transition metal oxides such as Fe ₂ O ₃ , NiO, Cr ₂ O ₃ and MnO ₂ are mainly used for the production of the metal oxide temperature sensor. Generally, the transition metal oxides are mixed with a sintering accelerator such as Al ₂ O ₃ , SiO ₂ , Y ₂ O ₃ , or a resistance adjusting agent, and then subjected to a ceramic process such as calcination and sintering, followed by a temperature sensor. Generally, such a ceramic temperature sensor exhibits a resistance value of 10 ⁶ ohm or more at room temperature and a resistance value of several ohm at a temperature of 700 ° C or higher. Therefore, it is not easy to increase the high temperature resistance of most ceramics.

However, as described above, the temperature sensor to be used in the exhaust apparatus of an automobile must be measured by a general-purpose instrument in a wide temperature range from a low temperature of about 0 ° C to a high temperature of about 900 ° C. The resistance of the oxide should be about 1 Mohm at 0 ℃ and about 30 ohm at 900 ℃. Therefore, the conventional ceramic temperature sensor is not suitable for use in an automobile exhaust system, and conventional metal oxide temperature sensors are classified according to use environments such as low temperature, medium temperature, and high temperature. On the other hand, ZrO ₂ has an infinite resistance value at room temperature, so it is mainly used as a temperature sensor for high temperature of 500 ° C or more.

In order to solve the problem that the high temperature resistance of the conventional ceramic temperature sensor is very low, a high temperature heat treatment of a high temperature resistant insulator or high resistance ceramics is separately performed to manufacture a high resistance material of a large particle, Thereby increasing the overall resistance, thereby completing the present invention to provide a technique for manufacturing a temperature sensor capable of precisely measuring in a temperature range from 0 ° C to 900 ° C.

Korean Patent Publication No. 10-2013-0128965

In order to solve the above problems, an object of the present invention is to provide a method for manufacturing a composition for a temperature sensor which can be used as a temperature sensor over a wide temperature range, and which has a high temperature resistance.

Another object of the present invention is to provide a composition for a temperature sensor manufactured by the method of the present invention.

It is another object of the present invention to provide a thermistor element using the composition for a temperature sensor of the present invention.

Another object of the present invention is to provide a temperature sensor including the thermistor element of the present invention.

(A) mixing ZrO ₂ and an additive for grain growth and phase stabilization, and then heat-treating the mixture at a temperature of 1,000 ° C to 2,000 ° C for 10 to 15 hours to produce a high-resistance material; (b) heat-treating the composition having the formula of Y _0.9 Ca _0.1 Al _0.38 Mn _0.54 Cr _0.08 O ₃ at a temperature of 1,000 ° C to 1,500 ° C for 1 to 5 hours to produce a low-resistance material; And (c) preparing a composition for a temperature sensor by mixing the high resistance material of step (a) and the low resistance material of step (b) at a temperature of 1,100 ° C to 1,700 ° C for 30 minutes to 2 hours And a method for manufacturing a composition for a temperature sensor.

In one embodiment of the present invention, the additive of the step (a) is selected from the group consisting of Y ₂ O ₃ , Al ₂ O ₃ , CeO ₂ , MgO, SiO ₂ , Ta ₂ O ₅ and ThO ₂ Or more.

In one embodiment of the present invention, the high resistance member in the step (a) has a diameter of 53 to 100 탆.

In one embodiment of the present invention, the mixing ratio of the step (a) to the powder of step (b) in the step (c) is 95: 5 to 5:95.

The present invention also provides a composition for a temperature sensor produced according to the method of the present invention.

The present invention also relates to a method for producing a molded article, comprising the steps of: preparing a molded article by injecting and pressing a composition for a temperature sensor of the present invention into a mold; Inserting and pressing the electrode line (20) into the formed body; And heat treating the formed body having the electrode line (20) inserted thereinto.

In the embodiment of the present invention, the step of pressing the primer molded article is characterized by applying a pressure in the same direction as the inserting direction of the electrode wire 20.

In an embodiment of the present invention, the step of heat-treating the formed body inserted with the electrode line 20 may be performed by thermally treating the molded body at 1300 to 1500 ° C for 0.5 to 5 hours to physically chemically react the formed body 10, So that they can be brought into close contact with each other.

In one embodiment of the present invention, the electrode line 20 is made of pure platinum (Pt) or an alloy of platinum-rhodium (Pt-Rh).

The present invention also provides a temperature sensor manufactured according to the method of the present invention.

In the case of the composition for a temperature sensor according to the present invention, the resistance of the temperature sensor at a high temperature and an appropriate resistance range can be secured by more easily controlling the resistance of the temperature sensor according to the temperature change. It has a resistance value of about 90? At 900 占 폚, so that it can be easily measured even at a temperature change of low temperature and high temperature.

1 is a cross-sectional view of a temperature sensor element according to an embodiment of the present invention.
2 is a graph showing a temperature-resistance measurement of a composition for a low-resistance material and a temperature sensor according to an embodiment of the present invention.

The present invention can be used in all of a wide temperature range, and is characterized in that it provides a composition for a temperature sensor having an increased high temperature resistance in particular.

Accordingly, the present invention provides a composition for a temperature sensor which is prepared by mixing a stabilized ZrO ₂ powder having a large particle size and a high resistance prepared by a high-temperature heat treatment at a temperature of 1,000 ° C. or higher, and a powder having a small particle size and low resistance, Wherein the temperature sensor is capable of measuring a resistance up to a range of a predetermined temperature.

The method for manufacturing a composition for a temperature sensor of the present invention comprises the steps of (a) mixing ZrO ₂ with an additive for particle growth and phase stabilization, and then heat-treating the mixture at a temperature of 1,000 ° C. to 2,000 ° C. for 10 to 15 hours to prepare a high- ; (b) heat-treating the composition having the formula of Y _0.9 Ca _0.1 Al _0.38 Mn _0.54 Cr _0.08 O ₃ at a temperature of 1,000 ° C to 1,500 ° C for 1 to 5 hours to produce a low-resistance material; And (c) preparing a composition for a temperature sensor by mixing the high resistance material of step (a) and the low resistance material of step (b) at a temperature of 1,100 ° C to 1,700 ° C for 30 minutes to 2 hours .

In the case of the high resistance material in the step a), it is a material exhibiting a high resistance which serves to increase the resistance of the entire composition for a temperature sensor of the present invention. The metal oxide used as the resistance material may be a single metal oxide as well as a composite metal oxide in which two or more phases are mixed, a metal oxide containing an additive for grain growth or phase stability, a metal element or a metal compound, and the like . In a preferred embodiment of the present invention, the metal oxide may be ZrO ₂ . Since ZrO ₂ exhibits infinite resistance at room temperature, it was mainly used only as a temperature sensor for high temperatures of about 500 ° C or more. Stabilized ZrO ₂ grown as large grains has almost insulator properties at room temperature, so it is difficult to measure with general-purpose instruments. However, it exhibits resistance of several hundred ohms at a temperature higher than about 900 ° C.

In the step (b), a semiconductive metal oxide, a composite metal oxide, or the like may be used as a step of producing a low resistance material having a low resistance value. Y _{0 .9} Ca _{0 .1} Al _{0 .38} Mn _{0 .54} Cr _{0 .0} O ₃ is an example of a small size particle exhibiting a low resistance value. The material is heated to a temperature of 1,000 ° C. to 1,500 ° C., preferably 1,200 ° C. Lt; 0 > C for about 2 hours.

The step c) is a step of mixing a high resistivity material of the step a), which is large in size and high resistance, and a low resistance material of step b), which is small in size and exhibiting a low resistance. When such large and small substances are mixed, the mutual reaction is minimized. Also, when a low resistance material and a high resistance material are mixed, a material having a low resistance becomes a main resistance component in a relatively low temperature range of 500 DEG C or less, and a high resistance in a relatively high temperature range of 500 DEG C or more The resistance value of the material having a smaller resistance value becomes smaller, so that a material having a resistance as high as the mixing ratio contributes to the resistance component, thereby increasing the overall resistance. Therefore, it is possible to measure the temperature over a wide temperature range with one sensor.

In one embodiment of the present invention, the metal oxide is ZrO ₂ and the small size particles exhibiting low resistance may be Y _{0 .9} Ca _{0 .1} Al _{0 .38} Mn _{0 .5} Cr _{0 .08} O ₃ have. According to the production method of the present invention, the Y _0.9 Ca _0.1 Al _0.38 Mn _0.54 Cr _0.08 O ₃ may be calcined at 1200 ° C for 2 hours and then pulverized to be used as a low-resistance powder of small particles.

Also, as a material for increasing the resistance of the low-resistance material, ZrO ₂ is heat-treated at 1,550 ° C for 12 hours to produce a powder exhibiting high resistance to large particles. At this time, the pure ZrO ₂ has a large volume expansion ratio due to the phase transition around 1,000 ° C., and it is necessary to stabilize it.

Thus, _{Y 2 O 3, CeO 2,} CaO, both of ZrO ₂ by the addition of MgO and so on added to 20 mol% monoclinic (monoclinic) tetragonal (cubic) from ZrO ₂ to the grain growth and the stabilization of the ZrO ₂ , But it is also possible to use ZrO ₂ which is reduced to 3 mol% of Y ₂ O ₃ , CeO ₂ , CaO, MgO or the like. The ZrO ₂ powder thus prepared functions as a phase-stabilized large-particle high-resistance material.

It is also possible to use a single component such as Al ₂ O ₃ , Y ₂ O ₃ , CeO ₂ , MgO, SiO ₂ , Ta ₂ O ₅ and ThO ₂ , which are high melting point and high resistance materials similar to ZrO ₂ , The slope control and the appropriate resistance value can be obtained even when the mixed metal oxide is mixed with a metal oxide doped with an additive for grain growth or phase stabilization, and a metal oxide or a metal oxide is oxidized with a low resistance material.

In addition, ZrO _{2, which} is a high-resistance material, can generate small particles in the grinding process for particle size classification. Smaller particles than the large particles have a high reactivity with the low-resistance material, so resistance and tilt control may be difficult. If the particle size is too small or too large, only a certain range of particles can be used to control the resistance and tilt of the temperature sensor more easily. The diameter of ZrO ₂ , which is a high-resistance material, is preferably in the range of 53 to 100 μm.

In order to minimize the reaction with low resistance Y _{0 .9} Ca _{0 .1} Al _{0 .38} Mn _{0 .5} Cr _{0 .0} O ₃ , ZrO ₂ , which is a high-resistance material of large particles, The ZrO ₂ resistance is very large, so that the composition of Y _0.9 Ca _0.1 Al _0.38 Mn _0.54 Cr _0.08 O ₃ having a low resistance becomes the main resistance component, and the ZrO ₂ resistance value becomes small at a high temperature in the range of 500 ° C. to 900 ° C., The ZrO ₂ contributes to the resistance component and increases the overall resistance. Therefore, one sensor can perform resistance measurement, that is, temperature measurement in the entire range from -40 ° C to 900 ° C. Since the normal ZrO ₂ stabilization temperature is 1300 ° C or lower, the particles grow very large when the heat treatment is performed at a high temperature of 1,550 ° C higher than the normal stabilization temperature.

Therefore, in the sintering process for densification, the diffusion distance for the reaction with the low-resistance material becomes far away and the reaction is minimized, so that the characteristic of the high-resistance ZrO ₂ is maintained during the sintering at 1,400 ° C.

In one embodiment of the present invention, a small-sized low-resistance powder having a formula of Y _{0 .9} Ca _{0 .1} Al _{0 .38} Mn _{0 .5} Cr _{0 .0} O ₃ calcined at 1,200 ° C. for 2 hours When the particles are mixed at a ratio of 7: 3 with the high-resistance ZrO ₂ powder stabilized by heat treatment at 1,550 ° C. for 12 hours and sintered at 1,400 ° C. for 1 hour, It is possible to provide a metal oxide sintered body capable of precisely measuring the temperature in the range.

Further, the present invention can provide a thermistor element or a temperature sensor using the composition for a temperature sensor. In general, temperature sensors are manufactured using metal or metal oxides. Temperature sensors used in high temperature environments are mainly made of metal oxides. Transition metal oxides such as Fe ₂ O ₃ , NiO, Cr ₂ O ₃ and MnO ₂ are mainly used for the production of the metal oxide temperature sensor. The transition metal oxide is mixed with a sintering accelerator such as Al ₂ O ₃ , SiO ₂ , Y ₂ O ₃ , or a resistance modifier, and the ceramic material is calcined and sintered. After manufacturing the test piece, electrodes can be printed or plated on the surface of the test piece, and a lead wire of Ni, Pt, Au, Cu or the like can be bonded to the surface of the test piece.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following Examples are only the preferred embodiments of the present invention, and the present invention is not limited by the following Examples.

< Example  1>

The metal oxide sample

As the metal oxide samples used in the present invention, metal oxides of Y ₂ O ₃ , CaCO ₃ , Al ₂ O ₃ , MnO ₂ , Cr ₂ O ₃ and ZrO ₂ were used. It is assumed that the chemical compositions thereof are assumed to be molar ratios even after the heat treatment, and that the metallic components can be used by oxidizing if necessary, and that the molar composition ratio of the transition metal oxide may be changed.

< Example  2>

Low resistance manufacturing

The composition of Y _0.9 Ca _0.1 Al _0.38 Mn _0.54 Cr _0.08 O ₃ having an Al content of 0.4 or less was selected as a composition for the production of a low resistance material. 0.1 mol, 0.38 mol, 0.54 mol, and 0.08 mol of Y ₂ O ₃ , CaCO ₃ , Al ₂ O ₃ , MnO ₂ and Cr ₂ O ₃ reagents were weighed and mixed with distilled water and ZrO ₂ The balls (10 mm and 2 mm balls were mixed at a ratio of 1: 2, wet mixed, dried, and calcined at 1400 캜 for 2 hours to synthesize low resistivity bodies.

< Example  3>

High resistance manufacturing

ZrO ₂ Was used and 20YSZ stabilized by adding 20 mol% Y ₂ O ₃ was used. ZrO ₂ has a monoclinic transition to tetragonal at 1200 ° C and a rapid volume change, so it must be stabilized in a single phase for uniform volume change. ZrO ₂ to which 20 mol% Y ₂ O ₃ was added was stabilized by heat treatment at a temperature equal to or higher than the ZrO ₂ melting point to prepare Yttria Stabilized Zirconia (YSZ). The stabilized ZrO ₂ (20YSZ) added with 20mol% Y ₂ O ₃ was used for every particle size range of 53-100um through pulverization, sieving or deflection.

< Example  4>

Manufacture of temperature sensor

The low resistance of _{Y 0 .9 Ca 0 .1 Al 0} .38 Mn 0 .54 Cr 0 .08 O 3 and a high resistance body of _{20YSZ (20mol% Y 2 O 3} added ZrO 2) 7: Determination in a mass ratio of 3, and And the mixture was mixed for 1 hour to achieve uniform mixing. A predetermined amount of the mixed powder was put into a mold and pressed to produce a molded body. The size of the molded body 10 was 2 x 2 x 2 mm, and the electrode 20 was a Pt-13% Rh alloy having a diameter of 0.3 mm. The electrode 20 was inserted so that the gap was 0.5 mm, and the electrode was formed by press-molding a part of a Pt-Rd alloy wire having a diameter of 0.3 mm and a length of 10 mm at the time of molding, as shown in Fig. The molded body was sintered in air at 1400 ° C for 2 hours to manufacture a temperature sensor.

< Experimental Example  1>

Resistance characteristic of temperature sensor

The temperature-resistance of the low resistance body of Example 2 and the temperature sensor of Example 4 was measured. 2, the resistance is measured at about 0.02 M? At a temperature of -40 占 폚, about 6? At a temperature of 900 占 폚, and the temperature of the temperature sensor of the fourth embodiment of the present invention - Resistance characteristic (40) In the case of the result, the resistance is measured at about 0.9 MΩ at -40 ° C. and about 90 Ω at 900 ° C. temperature.

Therefore, in the case of the composition for a temperature sensor having a high temperature resistance according to the present invention, the resistance of the temperature sensor according to the temperature change can be more easily controlled, the stability of the resistance value and the appropriate resistance range can be ensured at a high temperature, The resistance value according to the present invention is expressed in a range of about several MΩ at room temperature to about several tens of ohms at 500-600 ° C. Thus, the temperature change can be easily measured even at a high temperature.

The present invention has been described with reference to the preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is indicated by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

10: Molded body
20: Electrode line
30: Temperature-resistance characteristic of the low resistance material of the present invention
40: Temperature-resistance characteristic of the composition for a temperature sensor of the present invention

Claims (10)

(a) ZrO ₂ And additives for particle growth and phase stability, and then heat-treating the mixture at a temperature of 1,000 ° C to 2,000 ° C for 10 to 15 hours to produce a high-resistance material;
(b) a composition having the formula Y _{0 .9} Ca _{0 .1} Al _{0 .38} Mn _{0 .5} Cr _{0 .0} O ₃ is subjected to a heat treatment at a temperature of 1,000 ° C. to 1,500 ° C. for 1 to 5 hours to produce a low- ; And
(c) mixing the high-resistance material of step (a) and the low-resistance material of step (b) and thermally treating the material at a temperature of 1,100 ° C to 1,700 ° C for 30 minutes to 2 hours to prepare a composition for a temperature sensor , A method for manufacturing a composition for a temperature sensor. The method according to claim 1,
Wherein the additive in the step (a) is at least one selected from the group consisting of Y ₂ O ₃ , Al ₂ O ₃ , CeO ₂ , MgO, SiO ₂ , Ta ₂ O ₅ and ThO ₂ . Gt; The method according to claim 1,
Wherein the high resistance material in step (a) has a diameter of 53 to 100 mu m. The method according to claim 1,
Wherein the high resistivity material in step (a) and the low resistivity material in step (b) are mixed in a weight ratio of 95: 5 to 5:95 in step (c). A composition for a temperature sensor produced according to any one of claims 1 to 4. A process for producing a molded article according to claim 5, wherein the composition for a temperature sensor is put into a mold and pressurized to produce a molded article;
Inserting and pressing the electrode line (20) into the formed body; And
And thermally treating the formed body into which the electrode line (20) is inserted. The method according to claim 6,
Wherein the step of pressing the molded body applies a pressure in the same direction as the inserting direction of the electrode line (20). The method according to claim 6,
In the step of heat-treating the molded product into which the electrode line 20 is inserted, the molded product 10 is thermally treated at 1300 to 1500 ° C for 0.5 to 5 hours to physically chemically react the molded product 10 and adhere to the electrode line 20 Wherein the temperature sensor comprises: The method according to claim 6,
Wherein the electrode line (20) is made of pure platinum (Pt) or an alloy of platinum-rhodium (Pt-Rh). A temperature sensor manufactured according to any one of claims 9 to 9.

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