JPS5835903A - Moisture sensitive element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a humidity sensing element, and more particularly to a sensor that can be used in a wide range of humidity (has an electrical resistance that is easy to break) and can be used stably for a long period of time.

A large number of humidity sensors that measure and detect atmospheric humidity have been proposed and put into practical use. Particularly in recent years, humidity sensors that can directly detect humidity electrically have been proposed. As mentioned above, humidity sensors that directly electrically detect humidity are inexpensive, can detect low humidity with relatively high accuracy, and are stable over a long period of time. has not been obtained yet.

By the way, the fields that require simple and accurate detection control in low temperature ranges are extremely diverse, including industrial and consumer uses, and there is a strong desire to develop humidity sensors suitable for these uses. As a result of intensive research to meet the above requirements, the inventors of the present invention have developed a humidity sensor that has an electrical resistance value that is easy to use in a wide range of humidity ranges, and that can be used relatively stably over a long period of time. I found it.

■ That is, LiZnVO4 is 15~1-T-LZnO is 3
This is a moisture-sensitive element made of a sintered body having a mole width of 0 to 80 and AJ20355 to 19 mole as essential components.

The humidity sensing element according to the invention has a relative humidity of 10 at an ambient temperature of 25°C.
%, the electrical resistance value is approximately 700 KQ, which is more than two orders of magnitude lower than conventional humidity sensors, making it extremely easy to use. Further, at a relative humidity of 90%, the resistance value becomes approximately 5Ω, and the resistance value is easy to use over a wide range of a degree. By the way, it has been confirmed that the humidity-sensing characteristics of the moisture-sensing element according to the present invention change depending on the sintering temperature, although it also depends on the composition ratio. It was found that the body porosity was in the range of 15 to 30 cm.

Example I LC will be described in detail below.

First, the starting materials are lithium carbonate, vanadium oxide,
Fine powders of zinc oxide and aluminum oxide were used. This raw material powder was weighed as LiZnVO4, zinc oxide, and aluminum oxide so that the molar ratio was 11,451°45, respectively, and after boiling, they were mixed 24 hours a day in a bot mill. Thereafter, the mixture was dried at 120'O for 12 hours and then calcined at 900°C. Thereafter, the raw material powder was further wet-pulverized in a bot mill for 24 hours, and then dried again at 120"C for 12 hours.

Next, 2% by weight of polyvinyl alcohol was added as a binder to the thus obtained adjusted powder, and granulation was performed using a Raikai machine, followed by pressure molding.

Pressure molding was carried out at a pressure of 500 ic9/(1'j!) to obtain a disc-shaped molded body with a diameter of 5 mm and a thickness of approximately 4 mm. Both main surfaces of the obtained sintered body were polished with No. 2000 white arundum to obtain a sintered body with a diameter of 51EII and a thickness of 3.Next, ruthenium oxide paste was printed on both main surfaces of this sintered body with a screen. This was applied and then baked at a temperature of 700° C. to form an electrode, yielding a moisture-sensitive element as shown in FIG.

The humidity characteristics of the humidity sensing element according to the present invention thus obtained are shown in Figure 2.This humidity sensing element has a wide range of resistance, ranging from 670 Ω at an ambient temperature of 25°C and a relative humidity of 10 inches, to 6KQ at a relative humidity of 90 degrees. It has a resistance value that is extremely easy to use in the humidity range. Furthermore, when the porosity of the sintered body obtained at this time was measured by the water bale intrusion method, it was found that the porosity was 25g6.

In order to investigate the stability of the moisture sensitive element according to the present invention,
The results when the humidity sensing element was left standing are shown in Figures 3 and 4, respectively, under the following conditions: 40°C, 90°R, f(,), and low humidity (10°C, 10°R, H,). Although the resistance value changes slightly for a while after being left unused, it shows a stable resistance value after 400 hours, indicating that the humidity sensing element remains sufficiently stable even over a long period of time and can detect humidity with high accuracy. Confirmed.For other Examples and Comparative Examples, 5 compositions including Example 1 and their moisture sensitivity characteristics (humidity sensitivity characteristics are 25℃ios a)'t7i and 90'14
RreH, te fm) t table K q t.

As you can see from the margin table below, it is confirmed that all of them have resistance values that are easy to use in a wide range of humidity. Ta.

Furthermore, when the long-term stability was examined under the same conditions as in Example 1, it was confirmed that it showed almost the same changes as in Example 1 and was stable over a long period of time.

When the composition of Example 1 was sintered at various temperatures, the porosity of the sintered body did not change monotonically with the sintering temperature, but changed as shown in FIG. 5. f9 this time 25℃505! The resistance values of R゛ and H are also shown. When similar operations were performed for other examples, it was found that the porosity of the sintered body is preferably between 15 and 30 m in order to obtain good resistance values in a wide range of humidity.

As described above, it has been confirmed that the humidity sensing element according to the present invention has a resistance value that is extremely easy to use in a wide range of humidity, and is stable even over a long period of time, and is capable of detecting mourning humidity. can be said to be extremely remarkable.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a moisture-sensitive element according to the present invention, and FIG. 2 is a curve diagram showing the moisture-sensitive characteristics of the humidity-sensitive element according to the present invention. Figure 3: 611 and 11!4 showing the humidity sensitivity characteristics when left at 40°C, 90 S R, H, 10°C, 10
1R, HK A curve diagram showing the stability of moisture-sensitive characteristics when left as it is. Figure 5. A curve diagram showing the relationship between the sintering temperature and the resistance value and porosity amount of 25°C 5011 FL, H. Agent Patent attorney Noriyuki Chika (and 1 other person) Figure 1 □ 2
.

Claims (1)

[Claims] +1) %Zn0 in LiZnVO415-1Mo
A moisture-sensitive element comprising a sintered body containing 30 to 80 mo/14 AI20355 to 19 mo as an essential component. (2) The moisture-sensitive element according to claim 1, wherein the sintered body has a porosity of 15 to 30c6.