JPS61242927A - Production of moisture responsive sintered material of glass powder - Google Patents

Abstract

PURPOSE:To obtain a cyrstalline sintered material useful as a detecting material for humidity sensor, having improved moisture responsive properties, by mixing blended powder of V2O3, TeO2 and Li2O with Ag2O to give raw material powder, melting the powder under heating, grinding the molten material to give glass powder, molding the glass powder and sintering it. CONSTITUTION:A base component mixture consisting of 52.5-57.5wt% V2O3, 40.0-45.0wt% TeO2 and 2.5-7.5wt% Li2O is further mixed with 8.0-12.0pts.wt. Ag2O to give starting raw material powder, which is melted under heating and made into glass. Then, the glass is ground to give glass powder, which is molded into a desired shape and sintered to give a moisture responsive sintered material of glass powder. The sintered material having improved susceptibility to moisture is obtained by common raw materials, given sintering can be carried out without requiring specific facilities and operation for crystal control and this process is advantageous with respect to cost. It is useful as a detecting material for humidity sensor used for various industrial devices, household electrical appliances, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a moisture-sensitive glass powder sintered body useful as a sensing material for a humidity sensor.

[Prior art]

Many proposals have been made as sensing materials for humidity sensors, such as those made of organic polymers, metal oxides, composite metal oxides, or ceramics.

Incidentally, in recent years, as humidity-sensing devices have become smaller and recording density has increased, there has been a demand for moisture-sensitive sensing materials that have better performance, are highly reliable, and can be manufactured at low cost.

[Problem to be solved]

However, conventional moisture-sensitive sensing materials, with the exception of organic polymer materials, have problems with measurement accuracy and reproducibility, and organic polymers are limited in operating temperature and have poor durability. It is said that there are also problems. For this reason, there is a strong demand for the emergence of new moisture-sensitive sensing materials. The present invention has been made to meet this demand.

[Technical means and effects]

The method for producing a moisture-sensitive glass powder sintered body according to the present invention includes: V2OS: 52.5 to 57.5% by weight, TeO
2: 40.0 to 45.0% by weight, and L i 2O:
To 100 parts by weight of a mixed powder consisting of 2.5 to 7.5% by weight, 8.0 to 12.0 parts by weight of Ag2O, and if desired 8.0 to 12.0 parts by weight of Ag, O, and Kzo:
A powder mixture containing 5 parts by weight or less is used as a starting material, and the glass obtained by heating and melting this is crushed, and the glass powder is used as a sintering raw material to form a molded body of the desired shape and sintered. It is characterized by

The sintered body obtained by the method of the present invention has crystallinity, and by using this as a sensor element and detecting changes in electrical resistance due to moisture adsorption and desorption on its surface or inside, the humidity of the surrounding atmosphere can be detected. Can be measured with high precision.

The starting materials in the present invention are VzOs and Tea.

and Li2O (hereinafter referred to as the "basic component mixture") is prepared by blending A g t O or Ag, O, and 2O. The reason for limiting the constituent components is as follows. In addition, in the explanation below, "%
” is “% by weight” unless otherwise specified.

V2Os: 52.5-57.5% VzOs (vanadium pentoxide) is the main component of the glass in the present invention, and its amount in the basic component mixture must be at least 52.5%.

If it is less than 52.5%, although vitrification is possible, the electrical resistance of the resulting sintered body increases, impairing its suitability as a moisture-sensitive sensing material. On the other hand, if the amount exceeds 57.5% in the basic component mixture, the chemical durability will decrease and a problem will arise in the durability as a moisture-sensitive sensing material, so 57.5% is set as the upper limit.

Te Oz: 40. o~45.0% Tent (tellurium dioxide) is the v2O. Together with glass, it forms the main component of glass. Tl2 in the basic component mixture
The reason for limiting the amount of O3 to 40.0 to 45.0% is to ensure the chemical stability of the glass without impairing the moisture sensitivity of the resulting sintered body, and to prevent crystallization during the sintering process. This is to make it easier.

Lito: 2.5 to 7.5% Lizo (lithium oxide) has the effect of improving the moisture sensitivity performance of the obtained sintered body. In order to ensure this effect, it is necessary that the amount occupied in the basic component mixture be 2.5% or more. However, if a large amount is blended, the chemical durability will decrease and the durability as a sensing material will become a problem, so the upper limit is set at 7.5%.

Ag, 0: 8.0 to 12.0 parts by weight Ag2O (silver oxide) has the effect of lowering the electrical resistance of the obtained sintered body and improving its moisture sensitivity performance. In order to achieve this effect sufficiently, it is necessary to add at least 8.0 parts by weight to 100 parts by weight of the basic component mixture. However, if the amount is too large, the vitrification becomes unstable, so the upper limit is set at 12.0 parts by weight.

K2O: 5.0 parts by weight or less of 2O (potassium oxide) is optionally added to the basic component mixture together with the above Ag2O. This has the effect of increasing the amount of change in electrical resistance of the resulting sintered body with respect to changes in relative humidity. However, when combined in large quantities,
Since the electrical resistance value of the sintered body increases and it loses its practicality as a sensing material,
The upper limit is 5.0 parts by weight, preferably 3.0 to 5.0 parts by weight.

The starting materials prepared to the above composition are thoroughly mixed, placed in a heat-resistant container, for example, an aluminum crucible, and heated and melted to obtain glass. The heat melting process is performed at a temperature of 950 to 98
This can be carried out at 0°C for 12 to 15 minutes.

This glass is then ground, preferably finely ground (approximately 2
~IOμm), the obtained glass powder is molded into a desired shape as a firing raw material, and the molded body is fired at an appropriate temperature depending on the component composition, preferably at 230 to 300°C.

In the present invention, the starting raw material prepared to have a predetermined composition is once melted and vitrified, and the pulverized product is used as the sintering raw material, so the obtained sintered body has extremely high compositional homogeneity, Highly reliable as a detection material. Furthermore, since microcrystalization occurs in parallel with the sintering of the glass powder in the firing process, there is no need for special crystallization control techniques as in the case of ordinary ceramic sintered bodies.

In the present invention, a porous sintered body is produced by blending a suitable blowing agent, preferably urea, with glass powder obtained by heating and melting the starting raw material, and shaping and firing the mixture as a sintering raw material. can be obtained. The sintered body obtained in this way has good air permeability and a large reactive surface area, so
It has excellent moisture sensing performance and good processability, so it can be easily processed into sensor elements of any shape. The amount of the blowing agent to be blended is appropriately determined depending on the desired porosity of the sintered body, but if too large a amount is blended, the sintered body will become non-uniform. , 0.1 to 1.0 parts by weight).

〔Example〕

Starting materials (1) to (7) having the component composition shown in Table 1 are prepared by thoroughly mixing powders of raw L V, O, Tea, Li2O, and Ag and O. Place it in an aluminum crucible, cover it and heat it to a temperature of 950 to 980 degrees Celsius.
It takes 15 minutes to obtain a molten glass, which is ground into fine glass powder (2-10 μm). This glass powder is used as a sintering raw material, and it is filled into a mold with a predetermined shape.
Pressure Crab Pressure molding is performed at 70 kg f /cd to obtain a disc-shaped molded body (diameter 10 mm, thickness 2 mm). The sintered bodies (1) to (7) are obtained by taking this out of the mold and firing it in an air atmosphere at 300° C. for 1 hour.

After polishing both sides of the obtained sintered body, silver paste was applied to one side in parallel comb shapes with an interval of 0.5fi.
Baking is performed at 00°C to form parallel comb-shaped electrodes.

This was installed as a humidity sensor in a temperature-adjustable humidity chamber, and changes in electrical resistance with respect to changes in humidity at a temperature of 27° C. were measured using an insulation resistance meter. The measurement results are shown in Table 2. Further, regarding the perfume 7, the correlation between the relative humidity and the detected electrical resistance value is shown in FIG.

Oba Makarushi V2O3, 'reoz, Li2O, Agzo and,
Starting materials (21) to (27) having the component compositions shown in Table 3 were prepared by thoroughly mixing each powder of
Sintered bodies (21) to (27) were obtained under the same conditions as above, each sintered body was polished and a comb-shaped electrode was formed, and then the change in electrical resistance value with respect to humidity changes was measured in a constant humidity chamber ( However, the temperature inside the tank: 22°C). Table 4 shows the measurement results. Further, FIG. 2 shows the correlation between the relative humidity and the electrical resistance value for the perfume 27.

As is clear from the above results, the electrical resistance of the sintered body obtained by the present invention changes in response to changes in relative humidity over a wide range, so by detecting the electrical resistance, changes in the humidity of the surrounding atmosphere can be detected. You can know.

Table 1 Ingredient Composition m2 Table Electrical Resistance Measured Value (Ohms) Table 3 Ingredient Composition Table 4 Electrical Resistance Measured Values (Ohms) [Effects of the Invention] According to the present invention, moisture sensitivity is achieved by using common raw materials. A sintered body with excellent quality can be obtained. Moreover, the present invention
Since glass powder is used as the sintering material, the sintered body is extremely homogeneous in composition and has high reliability as a sensing material. The sintering does not require special equipment or operations for crystal control, and the desired sintering can be achieved using general firing conditions, which is advantageous in terms of cost.

The sintered body obtained by the present invention can be used as a detection material for humidity sensors, and can accurately measure the humidity of the surrounding atmosphere over a wide range from the change in electrical resistance. Since it has excellent durability and is inexpensive, it is useful as a detection material for humidity sensors used in various environments such as various industrial equipment and home appliances.

[Brief explanation of the drawing]

FIGS. 1 and 2 are graphs showing the correlation between relative humidity and electrical resistance measured using a sintered body obtained according to the present invention as a humidity sensor element. 41 λ) Hitai (Ohm)

Claims (3)

[Claims] (1) V_2O_5: 52.5-57.5% by weight, Te
O_2: 40.0 to 45.0% by weight, Li_2O: 2.
To 100 parts by weight of mixed powder consisting of 5 to 7.5% by weight, A
A starting raw material powder containing 8.0 to 12.0 parts by weight of g_2O is heated and melted to vitrify it, and the glass powder obtained by crushing this is formed into a desired shape as a sintering raw material and sintered. A method for producing a moisture-sensitive glass powder sintered body having crystallinity. (2) The starting raw material powder is added to 100 parts by weight of the mixed powder with Ag
_2O: 8.0 to 12.0 parts by weight, and K_2O: 5
The method for producing a moisture-sensitive glass powder sintered body having crystallinity according to item (1) above, characterized in that less than one part by weight is blended. (3) The above-mentioned (1) characterized in that 1.0 parts by weight or less of urea is blended with 100 parts by weight of glass powder to prepare a sintering raw material.
) or (2), the method for producing a moisture-sensitive glass powder sintered body.