JP3170341B2 - Molded body for thermal history detection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is for detecting a thermal history in a firing process of ceramics or the like.
The present invention relates to a molded body for detecting thermal history in firing in a non-oxidizing atmosphere in a temperature range of 0 to 1950 ° C.

[0002]

2. Description of the Related Art In the process of firing ceramics, the thermal history of the object to be fired changes depending on the temperature profile, the type of firing furnace, the settings in the furnace, and the like. That is, even if the firing temperature is the same, if other conditions are different, the thermal history will be different, and it is necessary to correctly detect the thermal history.

For example, the thermal history of a body to be fired has been detected using a Zegel cone disclosed in Japanese Utility Model Application Laid-Open No. 56-29441. A Zegel cone is one in which a plurality of triangular pyramids having different melting temperatures are provided on a support base.After firing this Zegel cone together with the object to be fired, the thermal history is determined by the manner in which each triangular pyramid falls. Was to be detected. However, since accurate detection is not possible with this, it is rarely used at present.

Accordingly, as shown in, for example, Japanese Patent Application Laid-Open No. 1-184388, after a ceramic green compact is fired together with a body to be fired, the dimensional change due to shrinkage is measured. By doing so, the thermal history has been detected. For example, a ring-shaped molded body 20 as shown in FIG. 2 or a sheet-shaped molded body 30 as shown in FIG. 3 has been used.

When such a dimensional change due to firing shrinkage is measured, the dimensional change is conveniently converted to a temperature. However, this temperature is not a measurement of the actual temperature, but a thermal history. Therefore, in the present invention, it is referred to as an indicated temperature.

[0006]

However, the above ceramic molded body for detecting thermal history is made of Al ₂ O ₃ —Si.
Since it was made of a natural raw material containing O ₂ or SiO ₂ —MgO as a main component and containing a large amount of impurities, the firing shrinkage ratio varied, and the accuracy of the detected indicated temperature was poor.

Further, in the ring-shaped one shown in FIG.
Since the volume is large, a large space is required in the firing furnace, and the sheet-shaped one shown in FIG. 3 has a problem that warpage occurs and dimensions cannot be measured correctly.

[0008]

Accordingly, the present invention provides an AlN
Molded article containing a binder mainly composed of
The ceramic unsintered molded body in which the total amount of cationic metals other than 1 is 0.3% by weight or less, or an oxygen amount of 0.4 to 5% by weight, a carbon amount of 0.5% by weight, and
A non-fired ceramic molded body having a total of 0.3% by weight of the cationic metal excluding l was used as a thermal history detection molded body.

In the present invention, the total amount of the cation metals excluding Al is set to 0.3% by weight or less. If the total is more than 0.3% by weight, the density is reduced to 1650 ° C. or less, and the heat history detecting molded body is formed. This is because the temperature tends to change, and the indicated temperature cannot be measured accurately.

The reason why the heat history detecting molded body after degreasing is set to have an oxygen content of 0.4 to 5% by weight is that if the oxygen content is less than 0.4% by weight, it hardly shrinks at 1950 ° C. If the amount is more than 5% by weight, the molded article for heat history detection is warped after sintering and is likely to be deformed.

The reason why the carbon content of the heat history detecting molded body after degreasing is set to 0.5% by weight or less is that if the carbon content is more than 0.5% by weight, it hardly shrinks at 1950 ° C. or less. This is because they are easily deformed.

According to the present inventors, the total amount of the cationic metal excluding Al in the heat history detecting molded body is 0.3% by weight or less,
By setting the amount of oxygen after degreasing to 0.4 to 5% by weight and the amount of carbon after degreasing to 0.5% by weight or less, 1650 to 195%
The indicated temperature can be accurately obtained at 0 ° C.

Furthermore, the reason why the amount of the binder in the molded article for detecting thermal history is set to 2 to 20% by weight is that if the amount of the binder is less than 2% by weight, the shape retention of the molded article is deteriorated and the amount of the binder is decreased. When the content is more than 20% by weight, the variation in firing shrinkage becomes large, and the reliability of the indicated temperature decreases. It was found that when the amount of the binder was 2 to 20% by weight, the shape retention was good, the variation in firing shrinkage was small, and the indicated temperature was reliable.

[0014]

Embodiments of the present invention will be described below.

As shown in FIGS. 1 (a) and 1 (b), a heat history detecting molded body 10 of the present invention has a chord portion 12 parallel to a disk body.
12 are formed, and the remaining arc portions are measurement surfaces 11 and 11 having excellent roundness. In addition, a concave portion 13 is formed on one side by engraving such as a dot or an alphabet for distinguishing the front and back sides, and a chamfer 14 is formed on the corners of the upper and lower surfaces.

Further, the molded body 10 is a molded body mainly composed of AlN and containing 2 to 20% by weight of a binder, wherein the total amount of cationic metals other than Al is 0.3% by weight or less. It has a composition in which the amount of oxygen afterwards is 0.4 to 5% by weight and the amount of carbon is 0.5% by weight or less. It is a green compact. And, as described below,
By changing the firing temperature under certain conditions, this compact 10
The dimensions after firing are measured, and the relationship between the dimensions and the firing temperature is prepared as a conversion table. Thereafter, when firing is performed under different conditions, the molded body 10 is fired together with the fired object, and the indicated temperature can be obtained from the above conversion table by measuring the dimensional change after firing.

As described above, the indicated temperature is not an actual temperature but a heat history for convenience. That is, by using the heat history detecting molded body of the present invention, even when firing conditions are different, it is possible to manage the heat history itself by obtaining the indicated temperature.

Although the molded article of the present invention can be used in various non-oxidizing atmospheres, it is better to perform degreasing before detecting the heat history.

Further, the molded body 10 of the present invention is characterized in that the chord 1
2 and 12, the area is smaller than that of the conventional example shown in FIG. 2, and a large space is not required in the firing furnace. Note that the chords 12 and 12 need not be parallel to each other, and may be formed only at one location. Furthermore, since the molded article 10 of the present invention is a press molded article having a thickness of about 3 to 10 mm, in special cases, for example, when the molded article for heat history detection is easily evaporated or when firing shrinkage is anisotropic. There is no warping except when there is a property, and at the time of dimension measurement, as shown in FIG. 1 (a), it is sufficient to measure between the arc-shaped measurement surfaces 11, 11 with a constant pressure micrometer. Even if the measurement position is shifted, the same diameter D can be accurately measured.

The shape of the molded article 10 of the present invention can be various as long as it is a simple shape having a uniform density.

Example 1 Various AlN powders alone or CaCO as an auxiliary agent
₃ and Yb ₂ O ₃ are added, wet-pulverized in methanol with a silicon nitride ball, and subjected to particle size analysis by a laser light scattering method to obtain an average particle diameter of 1.3 ± 0.1 μm. And 6% by weight of an acrylic binder and 1% by weight of a wax-based binder are added to this raw material powder, mixed and spray-dried to obtain granules having good fluidity. The granules are press-molded in an air-conditioned molding chamber into the shape shown in FIGS. 1 (a) and 1 (b).
A molded article for detecting heat history of the present invention was obtained in the range of 0 ± 0.005 g / cm ³ .

After degreasing these compacts at 550 ° C. for 3 hours in the air, 1950 ° C. for 3 hours at 1650 ° C. under N ₂ normal pressure.
Calcination was performed at 3 ° C. for 3 hours.

Table 1 shows the composition of the molded article for detecting heat history, and Table 2 shows the results. In Table 1, there was no change in the amount of the cationic metal other than Al before and after degreasing. In addition, No. 1.
6.7.9 is a comparative example.

[0024]

[Table 1]

[0025]

[Table 2]

It is clear from Tables 1 and 2 that the total of the cationic metals other than Al is more than 0.3% by weight. 9 is 195
Since it was densified at 0 ° C., it could not be used in the intended temperature range. In addition, No. In No. 9, a change occurred after firing in the heat history detecting molded body, and it was difficult to accurately measure the shrinkage.

In the case of No. 3 in which the oxygen content after degreasing was 0.32% by weight. In No. 1, the firing shrinkage at 1650 ° C. was extremely small at 0.3%, and the firing shrinkage at 1950 ° C. was as low as 2.0%. No. 3 having an oxygen content of 7.14% by weight after degreasing. In No. 6, the molded article for heat history detection was warped in the thickness direction after firing, and the molded article for thermal history detection was evaporated to form irregularities on the surface, so that it could not be used in the intended temperature range.

In the case of No. 3 having a carbon content of 0.67% by weight after degreasing. Sample No. 7 exhibited an extremely small shrinkage of 0.1% at 1650 ° C., almost no shrinkage at 1950 ° C., and warpage occurred in the thickness direction, so that it could not be used in the intended temperature range. On the other hand, the total of the cationic impurities except Al was 0.3% by weight or less, the oxygen content after degreasing was 0.4 to 5% by weight, and the carbon content after degreasing was 0.5% by weight or less. 2.
In 3.4.5.8, it was possible to detect the heat history in the target temperature range.

Example 2 An AlN powder was wet-pulverized with a silicon nitride ball in methanol and subjected to a particle size analysis by a laser light scattering method to obtain an average particle size of 1.2 ± 0.1 μm. And The binder shown in Table 3 is added to this raw material powder, mixed and spray-dried to obtain granules having good fluidity. The granules are press-molded in an air-conditioned molding chamber into the shapes shown in FIGS. 1 (a) and 1 (b).
The heat history detecting molded article of the present invention shown in Table 3 was obtained in the range of 0.005 g / cm ³ .

[0030]

[Table 3]

After degreasing these compacts in air at 550 ° C. for 3 hours, a sintering furnace calibrated and calibrated strictly for N 2
₍₂₎ Baking was performed in a normal pressure atmosphere at a temperature rising rate of 500 ° C./hour, a maximum temperature of 3 hours, and a temperature decreasing rate of 600 ° C./hour.
The dimensions of the molded body for heat history detection after firing were measured at 20 ° C. with a low constant pressure micrometer.

The firing temperature (indicated temperature) was variously changed, and firing of 20 molded bodies was repeated three times. The results are as shown in Tables 4 and 5.

[0033]

[Table 4]

[0034]

[Table 5]

Further, from the dimensional variation (3σ) at each temperature and the dimensional change per 1 ° C. (tangent slope) at that temperature, the detection accuracy of the indicated temperature = ± the dimensional variation / per 1 ° C. The detection accuracy of the indicated temperature (3σ) was calculated from the dimensional change.

As shown in Table 4, within the range of 1650 to 1950 ° C., the detection accuracy of the indicated temperature could be kept within ± 2 ° C.

Further, Table 4 shows the dimensions of the compact at each indicated temperature of 50 ° C. By measuring the dimensions more precisely at each designated temperature, a conversion table of the dimensions of the compact and the designated temperature is obtained. It can be.

The results shown in Table 5 show the detection accuracy of the dimensions at 1760 ° C., the dimensional variation, and the indicated temperature. From this result, it was found that the amount of binder was 20
Wt. No. 15 could not make the detection accuracy within ± 2.0 ° C. Although not shown in the table, the detection accuracy of the indicated temperature for each 50 ° C. at 1650 to 1950 ° C. is No. Nos. 10 to 14 are within ± 2 ° C. 15 was greater than ± 2 ° C.

In Example 2, the particle size of the raw material was 1.2 ± 0.1 μm and the green density of the molded product was 2.100 ± 0.005 g / cm ^{3 in} order to obtain a molded product for detecting thermal history. Are not limited to these values, and can be variously changed. Usually ± 0.2 for particle size
μm, and raw density ± 0.005 g / cm
^{If the} variation was suppressed within the range of ³ , the detection accuracy of the indicated temperature could be made ± 2 ° C.

Further, even if the atmosphere gas at the time of firing is Ar gas alone or a mixed gas of N ₂ 87.5% and H ₂ 12.5%, the pressure is changed from 0.9 to 3 atm. As in the case of Example 1 and Example 2, the molded body for detecting heat history of the present invention could have the detection accuracy of the indicated temperature within ± 2 ° C within the range of 1650 to 1950 ° C.

[0041]

As described above, according to the present invention, there is provided a molded article mainly composed of AlN and containing 2 to 20% by weight of a binder, wherein the total amount of cationic metals other than Al is 0.3% by weight. % Or less, the unfired ceramic body having a degreasing oxygen content of 0.4 to 5% by weight and a carbon content of 0.5% by weight or less is used as a heat history detection molded body, so that the indicated temperature measurement accuracy is obtained. Can be extremely high as ± 2 ° C., so that the firing step can be strictly controlled even if the firing conditions are changed, and an excellent sintered body can be obtained.

[Brief description of the drawings]

FIG. 1A is a plan view showing a heat history detecting molded body according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line XX in FIG. 1A.

FIG. 2 is a perspective view showing a conventional heat history detecting molded body.

FIG. 3 is a perspective view showing a conventional heat history detecting molded body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Heat history detection molded body 11 ... Measurement surface 12 ... String part 13 ... Depression 14 ... Chamfer

Claims (2)

(57) [Claims] 1. A molded body mainly composed of AlN powder and containing a binder, comprising a ceramic unfired molded body having a total content of cationic metals other than Al of 0.3% by weight or less. A molded article for detecting heat history, characterized by the following. 2. An oxygen content of 0.4 to 5 obtained by degreasing a binder contained in the heat history detecting molded body according to claim 1.
A molded article for detecting thermal history, comprising an unfired ceramic molded article having a carbon content of 0.5% by weight or less and a total content of cationic metals other than Al of 0.3% by weight or less.