JPS60201243A - Method for measuring refractoriness of porcelain clay - Google Patents

Abstract

PURPOSE:To measure the refractoriness of porcelain clay simply and with good precision by obtaining the temp. of an inflection point where the change from contraction to expansion occurs in thermal expansion measurement of a porcelain pressformed body. CONSTITUTION:Porcelain powder e.g. of <=74mum particle diameter is formed to cylindrical or cubical shape by using a pelletizing machine. The size of the formed body of about 10mm. diameter, about 3mm. height is used in a cylindrical body, and that of about 10mm. side is used in a cubical body. Said body is set in a thermal dilatometer and heated. By the heating, it expands thermally (1) up to some temp., but contracts (2) by sintering if the temp. is attained. If further the temp. is raised, since said body begins to melt at a specified temp. and vitrified, the gases generated therein can't be diffused to the outer part above the temp., and the expansion (3) is begun suddenly. The sudden inflection point is in good correlation with refractoriness by the JIS metod, and the temp. of said point is obtained as the refractoriness.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring the fire resistance of china clay for ceramics, and more specifically, the fire resistance of china clay is determined by measuring the inflection point at which contraction to expansion occurs in the thermal expansion measurement of a molded body of china clay. This article relates to a simple and accurate method for measuring the fire resistance of china clay, which is measured by measuring the temperature.

BACKGROUND ART Conventionally, the fire resistance of china clay prepared for making everyday tableware, tiles, sanitary ware, etc. is usually measured according to the method specified in J-Ko 5M8512 or J-Ko SR2204. However, these measurement methods have the following problems: (1) JISR2204 requires that the sample be ground to pass through a standard mesh sieve of 297 μm; (2) In the above refractory measuring method, the refractory can be measured by approximating deformation when the tip of the Seegel cone comes into contact with the pedestal. Although the condition is expressed by the number of a standard Segel cone, it is difficult to make accurate observations under high temperature conditions, and the obtained fire resistance depends significantly on the measurer and the accuracy of the standard Segel cone. Accurate refractory measurements are difficult for samples that expand at the temperature at which the test cone begins to bend. (4) Pottery clay is usually used with a thickness of 100 μm or less.
Comparing the fire resistance with a standard Segel cone using a 297 μm sieve pass-through sample specified in 2204 has problems such as being impractical, and is not necessarily satisfactory.0 The present invention In view of these circumstances, we have conducted intensive research on a method for easily and accurately measuring the fire resistance of china clay without individual errors, and as a result, we have created a molded body of china clay with a specific shape, and measured the thermal expansion of this material. This purpose can be achieved by measuring the temperature at the inflection point where the transition from contraction to expansion occurs during measurement, and also the fire resistance determined by this method and the JIS standard.
It was discovered that there is a good correlation between the fire resistance by the method and the present invention was completed.

That is, the present invention provides a method for measuring the fire resistance of china clay.
The present invention provides a method for measuring the fire resistance of china clay, which is characterized by molding china clay powder into a cylinder or cube shape, heating the molded body, and measuring the temperature at the inflection point where the contraction changes to the expansion.

In the measuring method of the present invention, first, the particle size is 74 μm or less (approximately [3Q'wt% less than 20 μm, approximately 6Q'wt% less than iQ μm,
wt%, 5 μm or less approximately 50 wt%, 1 μm or less approximately 25
The wt%-containing soil powder is molded into a cylindrical or cubic shape using a pellet molding machine. The size of this molded body is usually cylindrical, with a diameter of about 1 g and a height of about 3 g.
The one in the order of mW, and the cubic one has a side of about 10
A horse-sized horse is used.

Next, the china clay molded body created in this way was measured using a thermal dilatometer (
Cosset and heat. By this heating, the molded body thermally expands up to a certain temperature, but when the temperature exceeds this temperature, it contracts due to sintering. If the temperature is further increased, the molded body will begin to melt and become vitrified at a certain temperature, so above this temperature the gas generated inside will no longer be able to diffuse to the outside and will begin to expand rapidly. .

Figure 1 shows a molded object (cylindrical shape with a diameter of 1011III and a thickness of 3 gm) made using china clay powder obtained from Amakusa pottery stone.
It is a graph which shows an example of the relationship between the temperature and the displacement amount of thickness in .

As can be seen from this figure, the molded body thermally expands gradually up to about 1000'Q, but when this temperature is exceeded, it begins to shrink and rapidly expands at an inflection point of about 1400°C.

The above-mentioned inflection point has a good correlation with the fire resistance according to the JIS method, and in the present invention, the temperature at this inflection point is taken as the fire resistance.

In the present invention, the fire resistance obtained in advance as described above and JIS M8512 or J Engineering 5R22 can be used as desired.
A relational expression with the fire resistance determined by the fire resistance test method of No. 04 is created, and from this relation, the fire resistance can be expressed as a number corresponding to the fire resistance according to the Seegel cone.

FIG. 2 is a graph showing an example of the relationship between the fire resistance (temperature at the inflection point) according to the present invention of china clay obtained from various Amakusa pottery stones and the fire resistance according to the JIS method.

The correlation coefficient between the two refractory degrees determined from FIG. 2 is 0.94, and it can be seen that there is a good correlation between the two refractory degrees. Also,
The relational expression between the two, determined by the least squares method based on this figure, is A = [ ], 83 The temperature at the inflection point is expressed in degrees Celsius.

When the fire resistance according to the method of the present invention is expressed by a number corresponding to the Segel cone, a relational expression as shown in the above equation (1) is created in advance, and the temperature at the inflection point is substituted into the relational expression. Alternatively, you can obtain the value obtained by converting the refractory degree according to the JIS method into a temperature, and calculate the number of the refractory degree according to the JIS method from this temperature.

According to the method for measuring the fire resistance of china clay of the present invention, the fire resistance of china clay can be measured more easily and accurately than the conventional method specified in JIS, and the method of the present invention is extremely practical. It is also an effective method for quality control of china clay.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 0.5 g of dry powder of china clay obtained from Amakusa pottery stone, which can be made into china clay by simply crushing, was reduced and molded into a cylindrical shape with a thickness of 3 hiH using a pellet molding machine with an inner diameter of 10 shoes. This pellet was set in a thermal dilatometer, and a temperature-thickness displacement curve of the pellet was determined. An example is shown in FIG.

As can be seen from FIG. 1, the pellet expands thermally up to about 1000' due to heating, but above this temperature it begins to shrink due to sintering. Furthermore, the beret is 14
Since it begins to melt and vitrify at around 00°C, at temperatures above this temperature the gas generated inside cannot diffuse to the outside and begins to expand.

Figure 2 also shows the fire resistance measured by the JIS method using china clay obtained from various Amakusa pottery stones, and the fire resistance of the above-mentioned types having the same particle size distribution as that used in the JE method. The graph shows the relationship between the degree of fire resistance measured on the thermal expansion side using china clay obtained from Amakusa Toseki.

From FIG. 2, it can be seen that the correlation coefficient between the two refractory ratings is 0.94, and there is a good correlation between the two refractory ratings. Also, the relational expression between the two obtained by the least squares method based on this figure is shown below.

A = 0.83 X B + 378 However, A is
The value obtained by converting the refractory degree by the rIs method into temperature ('Cri (
J Engineering 8 R8101), and B is the temperature at the inflection point measured by a thermal C dilatometer (00).

, 4. Brief explanation of the drawings Figure 1 is a graph showing an example of the relationship between temperature and thickness variation in a china clay molded body, and Figure 2 is a graph showing the fire resistance of the china clay according to the present invention and the fire resistance according to the JIS method. It is a graph which shows an example of the relationship between.

Patent applicant: Director of the Agency of Industrial Science and Technology
) Figure 2 Otsu thermal expansion Hanchu/Yl Fuhiro (°C) Continued from page 1 ■ Inventor Tsunematsu Kinue 0 Inventor Satoshi Nishimura 80 Nonoshita, Shukucho, Tosu City Kyushu Institute of Industrial Science and Technology Inside the testing laboratory

Claims (1)

[Claims] 1. To measure the fire resistance of china clay, we mold china clay powder into a cylinder or cube shape, heat this molded body, and measure the temperature at the inflection point where it changes from contraction to expansion. A method for measuring the fire resistance of china clay. 2 Fire resistance is 1. TI8 M8512 Mataha JIS R2
204 (D) The measuring method according to claim 1, which corresponds to the standard Segel cone fire resistance claimed by the fire resistance test method.