JPH05302857A - Thermal hysteresis detector - Google Patents

Abstract

PURPOSE:To obtain the highly accuracy for the measured accuracy of indicated temperature by forming a molded body of an unbaked ceramic molded body so that AlN is the main body, a binder is contained in the molded body and the amount of cation metals other than Al is a specified amount or less. CONSTITUTION:In a thermal hysteresis detector 10, chord parts 12 and 12, which are in parallel with a disk body, are formed, measuring surfaces 11 and 11 having the excellent roundness are formed as the arc parts, a recess part 13, which distinguishes the upper and rear surfaces, is formed in one surface, and chamfered parts 14 are provided at the corner parts of the upper and lower surfaces. Furthermore, the main body of the detection is AlN. The molded body 10 contains a binder of 2-20wt.%. The total of cation metals other than Al is 0.3wt.% or less. The amount of oxygen after degreasing is 0.4-5wt.% and the amount of carbon is 0.5wt.% or less in this composition. The detector is an unbaked ceramic compact. The relationship between the size after baking and the baking temperature is formed as a conversion table. The size after the baking is measured, and the indicated temperature is obtained from the conversion table. The measuring accuracy of the indicated temperature can be made accurate as high as + or -2 deg.C. Even if the baking conditions are changed, the baking step can be strictly controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is for detecting the thermal history of ceramics or the like during the firing process, and in particular 165 of aluminum nitride, silicon nitride, titanium nitride, etc.
The present invention relates to a molded article 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 firing process of ceramics, the thermal history of the body 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, the thermal history will be different if other conditions are different, and it is necessary to correctly detect this thermal history.

For example, the thermal history of a body to be fired has been detected using a Zegel cone as disclosed in Japanese Utility Model Laid-Open No. 56-29441. Zegel cones are provided with a plurality of triangular pyramids having different melting temperatures on a support, and after firing this Zegel cone together with the body to be fired, the thermal history of the triangular pyramids falls, It was supposed to detect. However, since it cannot detect accurately, it is now less used.

Therefore, as disclosed in, for example, Japanese Unexamined Patent Publication (Kokai) No. 1-184388, an unsintered compact of ceramics is used, and this compact is fired together with the body to be sintered, and then the dimensional change due to shrinkage is measured. By doing so, the thermal history was 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 was used.

When measuring such a dimensional change due to firing shrinkage, the dimensional change is conveniently converted into a temperature, but this temperature does not represent an actual temperature but represents a thermal history. Therefore, in the present invention, it is referred to as an instruction temperature.

[0006]

However, the above-mentioned ceramic molded body for thermal history detection has a problem of Al ₂ O ₃ --Si.
Since it was made of a natural raw material containing O ₂ or SiO ₂ —MgO system 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 shape shown in FIG.
Since the volume is large, a large space is required in the firing furnace, and the sheet-like material shown in FIG. 3 has a problem that warpage occurs and the dimension cannot be measured correctly.

[0008]

Therefore, the present invention is directed to AlN
A molded article containing a binder mainly composed of
Ceramics unfired compact having a total of 0.3% by weight or less of cation metals other than 1 or 0.4 to 5% by weight of oxygen and 0.5% by weight of carbon obtained by degreasing this, A
A ceramic unfired molded body containing 0.3% by weight of cation metals excluding 1 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 because if it is more than 0.3% by weight, it is densified below 1650 ° C. This is because changes in temperature tend to occur and the indicated temperature cannot be measured accurately.

The oxygen content of the molded article for detecting heat history after degreasing is set to 0.4 to 5% by weight, because when the oxygen content is less than 0.4% by weight, there is almost no shrinkage at 1950 ° C. This is because if the amount is more than 5% by weight, the heat history detection molded body is easily warped and deformed after sintering.

Further, the carbon content of the heat history detecting molded body after degreasing is set to 0.5% by weight or less, because when the carbon content is more than 0.5% by weight, it does not shrink at 1950 ° C. or less, and , Because it is easily deformed.

According to the present inventors, the total amount of cation metals excluding Al in the heat history detection molded body is 0.3% by weight or less,
By adjusting 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 determined at 0 ° C.

Further, the amount of the binder in the molded article for detecting thermal history is set to 2 to 20% by weight because the shape retention of the molded article becomes poor when the amount of the binder is less than 2% by weight, and the amount of the binder is reduced. If 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-retaining property was good, the variation in firing shrinkage was small, and the indicated temperature was reliable.

[0014]

EXAMPLES Examples of the present invention will be described below.

As shown in FIGS. 1 (a) and 1 (b), the heat history detecting molded body 10 of the present invention has a chord portion 12 parallel to the disc body.
12 is formed, and the remaining circular arc portions are the measurement surfaces 11 and 11 having excellent roundness. Further, a concave portion 13 is formed on one surface by marking such as dots or alphabets for distinguishing the front side and the back side, and chamfers 14 are provided at upper and lower corners.

Further, the molded body 10 is a molded body mainly composed of AlN and containing 2 to 20% by weight of a binder, and the total amount of cation metals other than Al is 0.3% by weight or less. The subsequent oxygen content is 0.4 to 5% by weight, and the carbon content is 0.5% by weight or less. The particle size of the raw material powder and the green density of the compact are controlled very strictly, and the press molding is performed. It is an unfired compact. And, as described below,
By changing the firing temperature under certain conditions, the molded body 10
Measure the dimensions after firing and prepare the relationship between the dimensions and firing temperature as a conversion table. After that, when firing is performed under different conditions, the molded body 10 is fired together with the body to be fired, and the dimensional change after firing is measured, so that the indicated temperature can be obtained from the conversion table.

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

The molded product of the present invention can be used under various non-oxidizing atmospheres, but it is better to degrease it before detecting the thermal history.

Further, the molded body 10 of the present invention has the chord portion 1
Since it has 2 and 12, it has a smaller area than the conventional example shown in FIG. 2 and does not require a large space in the firing furnace. The string portions 12 and 12 do not have to be parallel to each other, and may be formed at only one place. Further, since the molded product 10 of the present invention is a press-molded product having a wall thickness of about 3 to 10 mm, it is anisotropic in a special case, for example, when the thermal history detection molded product itself is easily evaporated or firing shrinkage occurs. Except when there is a property, warping does not occur, and at the time of dimension measurement, as shown in FIG. 1 (a), a constant pressure micrometer may be used to measure between the arc-shaped measurement surfaces 11, 11. Even if the measurement position is shifted, the same diameter D can be accurately measured.

The shape of the molded body 10 of the present invention may 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 were 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 size of 1.3 ± 0.1 μm. And 6 wt% of acrylic binder and 1 wt% of wax 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), and the green density of the molded body is 2.10 at this time.
A molded article for heat history detection of the present invention was obtained in the range of 0 ± 0.005 g / cm ³ .

These molded bodies were degreased in air at 550 ° C. for 3 hours, and then at 1650 ° C. in N ₂ normal pressure for 3 hours.
It was calcined at ℃ for 3 hours.

Table 1 shows the composition of the molded article for heat history detection, and Table 2 shows the results. In Table 1, there was no change in the amount of cation 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 apparent from Tables 1 and 2 that the total amount of cation 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, it was difficult to measure the shrinkage rate accurately because the molded product for heat history detection changed after firing.

In addition, the oxygen content after degreasing was 0.32% by weight. No. 1 had a very small firing shrinkage of 0.3% at 1650 ° C and a small firing shrinkage of 2.0% at 1950 ° C, and thus could not be used in the intended temperature range. The oxygen content after degreasing was 7.14% by weight. No. 6 could not be used in the intended temperature range because the molded article for heat history detection was warped in the thickness direction after firing and the molded article for heat history detection was itself evaporated to form irregularities on the surface.

[0028] Further, No. 1 having a carbon content of 0.67% by weight after degreasing. No. 7 had an extremely small firing 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, No. 3 having a total of 0.3 wt% or less of cationic impurities except Al, an oxygen amount after degreasing of 0.4 to 5 wt% and a carbon amount after degreasing of 0.5 wt% or less. 2.
In 3.4.5.8, it was possible to detect the thermal history in the target temperature range.

Example 2 AlN powder was 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 size of 1.2 ± 0.1 μm. And Binders shown in Table 3 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). At this time, the green density of the molded body is 2.100 ±.
The heat history detection molding 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 molded bodies in the air at 550 ° C. for 3 hours, the molded product was N
₂ Firing was performed in a normal pressure atmosphere with a temperature rising rate of 500 ° C./hour, a maximum temperature of 3 hours, and a temperature lowering rate of 600 ° C./hour.
The dimensions of the molded body for detecting thermal history after firing were measured at 20 ° C. with a low constant pressure micrometer.

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

[0033]

[Table 4]

[0034]

[Table 5]

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

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

Further, although Table 4 shows the dimensions of the molded body for each indicated temperature of 50 ° C., a conversion table for the dimensions of the molded body and the indicated temperature can be obtained by measuring the dimensions for each of the finer indicated temperatures. Can be

The results shown in Table 5 show the detection accuracy of the dimensions at 1760 ° C., the variation in dimensions, and the indicated temperature. From this result, the binder amount is 20
No. more than wt. No. 15 could not keep the detection accuracy within ± 2.0 ° C. Further, 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, while No. 15 was larger 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 article was 2.100 ± 0.005 g / cm ^{3 in} order to obtain the molded article for heat history detection. , Are not limited to this value, and can be variously changed. Normally, the particle size is ± 0.2
It is controlled by μm and the raw density is ± 0.005g / cm
^{If the} variation was suppressed within the range of ³ , the detection accuracy of the indicated temperature could be ± 2 ° C.

Further, Ar gas alone or a mixed gas of N ₂ 87.5% and H ₂ 12.5% was used as the atmosphere gas at the time of firing and the pressure was changed from 0.9 atm to 3 atm. As in the case of Example 1 and Example 2, the heat history detection molded body of the present invention was able to detect the indicated temperature within ± 2 ° C within the range of 1650 to 1950 ° C.

[0041]

As described above, according to the present invention, a molded body mainly composed of AlN and containing 2 to 20% by weight of a binder, and the total amount of cation metals other than Al is 0.3% by weight. % Or less, the amount of oxygen after degreasing is 0.4 to 5% by weight, and the amount of carbon is 0.5% by weight or less, the ceramics unfired molded body is used as a thermal history detection molded body, thereby measuring accuracy of the indicated temperature. Since the temperature can be extremely high at ± 2 ° C., the firing process can be strictly controlled even if the firing conditions are changed, and an excellent sintered body can be obtained.

[Brief description of drawings]

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

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

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

[Explanation of symbols]

 10 ... Mold for heat history detection 11 ... Measurement surface 12 ... Chord portion 13 ... Recessed portion 14 ... Chamfer

Claims (2)

[Claims] 1. A compact comprising a powder of AlN as a main component and containing a binder, wherein the total content of cation metals other than Al is 0.3 wt% or less. A molded article for detecting heat history, characterized by: 2. An oxygen content of 0.4 to 5, which is obtained by degreasing the binder contained in the molded article for thermal history detection according to claim 1.
A molded product for thermal history detection, comprising a ceramic unfired molded product having a weight%, a carbon content of 0.5% by weight or less, and a total content of cation metals other than Al of 0.3% by weight or less.