JPS62207759A - Raw material for cordierite - 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 (Technical Field) The present invention relates to a raw material for forming cordierite, and particularly relates to a raw material for forming cordierite that can stably produce a ceramic body having a low coefficient of thermal expansion, and a method for identifying the same. It is something.

(Prior art and its problems) Conventionally, cordierite forming raw materials composed of magnesia source materials, silica source materials, and alumina source materials such as talc, kaolin, and alumina are used as starting materials.
The cordierite ceramic body obtained by then forming a predetermined compact and firing the compact provides a product that is heat resistant and has a low coefficient of thermal expansion over a wide temperature range. For this reason, it has received particular attention as a honeycomb-shaped catalyst carrier material used in devices for purifying hydrocarbons, carbon oxides, and nitrogen oxides in various exhaust gases. Among various types of exhaust gas purification devices, ceramic honeycomb catalyst carriers used in automobile exhaust gas purification devices in particular are exposed to severe thermal shock. IX
Those with a high coefficient of thermal expansion of 10-h/'C (40 to 800 degrees Celsius) or higher cannot withstand thermal shock in actual use and have a high risk of breakage, so the coefficient of thermal expansion is at least 1.
0X10-6/°C (in the range of 40°C to 800°C.

(same below) or less, preferably 0.8 x 10-'/℃
It is required that:

For this reason, JP-A-50-75611 discloses a technique for reducing thermal expansion by orienting kaolin, which is one of the components of the raw material for forming cordierite. Publication No. 82822 discloses a technique for achieving low thermal expansion by maintaining the particle size of a magnesia source raw material such as talc, which is one of the constituent components of the raw material for forming cordierite, within a predetermined range.
Furthermore, techniques for achieving low thermal expansion have been revealed by examining the composition point and firing conditions of cordierite, which is composed of silica, alumina, and magnesia.

However, when manufacturing cordierite ceramic bodies, various natural raw materials such as talc and kaolin are blended and used as the raw materials for forming cordierite, so the conventional low thermal expansion characteristics described above are achieved. Simply managing the chemical analysis and particle size of cordierite-forming raw materials for each lot in accordance with the means to achieve this has the problem of causing an abnormal increase in the coefficient of thermal expansion of the cordierite ceramic body obtained by firing. . In other words, the thermal expansion coefficient of the resulting cordierite ceramic body varies greatly depending on the raw material preparation conditions, and this makes it extremely difficult to stably produce cordierite ceramic bodies with a low thermal expansion coefficient. It was.

By the way, in order to stably produce a cordierite ceramic body with the desired thermal expansion characteristics, especially low thermal expansion characteristics, the overall quality of the cordierite forming raw material as a compound for producing such a cordierite ceramic body must be checked. However, to date, no answer has been clarified regarding the relationship between the raw material for forming cordierite and the thermal expansion characteristics of the cordierite ceramic body obtained by firing it. Therefore, the reality is that no proposals have been made regarding means for stably realizing the low thermal expansion characteristics of such cordierite ceramic bodies.

(Object of the invention) The present invention has been made against this background, and its main purpose is to:
Prior to manufacturing the cordierite ceramic body,
The object of the present invention is to provide a method for evaluating the quality of a cordierite forming raw material that provides such a cordierite ceramic body.

Another object of the present invention is to provide a method for predicting the thermal expansion characteristics of a cordierite ceramic body produced from a raw material for forming cordierite and for effectively controlling the quality of such raw material for forming cordierite. Furthermore, by evaluating a part of the cordierite-forming raw material, the cordierite ceramic body obtained from the cordierite-forming raw material in the state of mixed powder, molded product, or molding clay. An object of the present invention is to provide a quality evaluation means that allows the thermal expansion characteristics of a material to be confirmed in advance in a short period of time.

Furthermore, another object of the present invention is to provide a method for evaluating or identifying the quality of raw materials for forming cordierite, which can stably produce cordierite ceramic bodies having low thermal expansion characteristics.

(Structure of the Invention) In order to achieve the above object, the present invention provides a method for evaluating the quality of a cordierite-forming raw material that gives a predetermined cordierite ceramic body by firing.
For a heat-treated sample of a predetermined press-molded body obtained using the cordierite-forming raw material, the X-ray diffraction intensity of the pressurized surface at the time of molding was determined and calculated using the following formula: R = I p (310) / I c ( 100)(
However, Ip (310): protoenstatite (31
0) plane peak intensity I c (100) : peak intensity of the (100) plane of cordierite] A cordierite ceramic body obtained from the cordierite forming raw material according to the value of cordierite reactivity ratio: R shown as By evaluating the thermal expansion characteristics of
The present invention is characterized in that the quality of the cordierite-forming raw material is determined.

In addition, in the method of the present invention, the heat-treated product of the press-molded sample is generally heated at a temperature of about 50°C/
Heating at a heating rate of ~350°C/hour, 128
0°C to 1330°C, preferably 1300°C to 1310°C
It is obtained by rapid cooling immediately after reaching the temperature of Therefore, it is possible to make an evaluation based on that information.

In addition, in the present invention, X-ray diffraction is performed and Ip(310
) and Ic (100) are preferably formed as a honeycomb structure or a press-formed product, and the rib surface of the honeycomb structure or the press of the press-formed product is preferably formed as a honeycomb structure or a press-formed product. The molding surface is used as a pressurizing surface, and the X-ray diffraction intensity is determined on such a pressurizing surface.

Furthermore, according to a preferred embodiment of the present invention, the cordierite reactivity ratio: R is expressed by the following formula: % formula %) (where T is the heat treatment temperature of the press-molded body sample, and is 1280°C to 1330°C). The coefficient of thermal expansion of the cordierite ceramic body is evaluated to be less than or equal to 1.0X 10-6/°C, and such cordierite ceramic body By manufacturing the desired cordierite ceramic body using a cordierite forming raw material that gives a light reactivity ratio R, a cordierite ceramic body with a low coefficient of thermal expansion,
In particular, it has become possible to stably obtain ceramic honeycomb catalyst carriers for various exhaust gas purification devices, especially automobile exhaust gas purification devices.

(Specific explanation of the structure) By the way, the cordierite forming raw material evaluated according to the present invention is a magnesia source raw material and a silica source raw material that are formulated to have the same chemical composition as a conventional cordierite ceramic body. and an alumina source material. More specifically, raw materials such as talc, calcined talc, magnesium carbonate, magnesium hydroxide, magnesium oxide, aluminum hydroxide, alumina, kaolin, calcined kaolin, and silica are appropriately selected to produce conventional cordierite. The cordierite-forming raw material is prepared so that it has the same proportions of silica, alumina, and magnesia as the cordierite-forming raw material that provides the ceramic. Note that the ratio of silica, alumina, and magnesia in this cordierite-forming raw material is generally silica: 42
~56% by weight, alumina: 34-48% by weight and magnesia: 10-18% by weight, preferably silica: 44-5%.
3% by weight, alumina: 35-45% by weight, and magnesia = 12-16% by weight.

The present invention is based on the fact that the reactivity of raw material particles in the cordierite reaction process of the cordierite-forming raw material has a large effect on the most important coefficient of thermal expansion in sintered cordierite (cordierite ceramic body). It was completed by In other words, depending on the preparation conditions of the cordierite-forming raw material, cordierite begins to crystallize at extremely low temperatures below 1250°C, even though the physical properties such as particle size are apparently exactly the same.
Cordierite formation in the liquid phase reaction, which is the main reaction at temperatures above However, it was found that a cordierite ceramic body having the desired thermal expansion characteristics could not be obtained. In other words, 1200℃~135
The thermal expansion coefficient of the final product, the cordierite ceramic body, is largely dependent on the cordierite crystallization situation in the 0°C region, and the cordierite forming raw material that provides the cordierite ceramic body with an abnormal thermal expansion coefficient is In such a temperature range, cordierite crystallizes quickly, and is suppressed by the solid phase crystallized cordierite, causing the liquid phase crystallization degree to shift to the high temperature side, and the balance with the amount of intermediate product crystallization is disrupted. It has become clear that this results in an increase in the coefficient of thermal expansion of the final product.

Therefore, in the present invention, when forming cordierite, the amount of crystallization of protoenstatite, which is an intermediate product, and the amount of crystallization of cordierite are determined in advance of the press-molded body obtained from the raw material for forming cordierite. A given heat-treated sample was examined by X-ray diffraction to determine its cordierite reactivity ratio:
The quality of the raw material for forming cordierite is evaluated based on the good correspondence between R and the coefficient of thermal expansion, and thereby the desired cordierite ceramic body can be obtained from the raw material for forming cordierite. This made it possible to estimate the coefficient of thermal expansion of a sintered body obtained during normal firing (firing operation at 1350°C to 1440°C).

In addition, contents that can be checked by the cordierite reactivity ratio: R determined according to the present invention include N in the cordierite forming raw material, especially in talc and kaolin.
az 05Kg 01 The coefficient of thermal expansion increases when there is a large amount of alkaline components such as CaO, the coefficient of thermal expansion increases due to the use of fine raw materials, and the reactivity increases due to mechanochemical effects due to the influence of the raw material crushing process, For example, there is an increase in the coefficient of thermal expansion due to recycled raw materials, and it is possible to completely check for abnormalities in these cordierite-forming raw materials due to promotion of solid-phase cordierite crystallization. In addition, even if the reactivity is normal, the cordierite reactivity ratio: R is Since it is calculated based on the term of the amount of cordierite (100) crystallized, which includes the gender factor, it is possible to check this.

Here, when investigating the cordierite reactivity ratio: R of such a cordierite-forming raw material, first use a part of the raw material, and then make a sample of a predetermined size (
A pressure-molded product) is pressure-molded by a suitable molding method such as extrusion molding or press molding. In addition, when molding the sample by press molding, if pressed at too high a pressure, the raw material particles will be destroyed and the reactivity will change, so the bulk density of the molded product should be 1.8 g/cm.
It is desirable that the sample be press-formed so that it does not become too high, and the sample should preferably be of a small size that does not break even when rapidly cooled from a high temperature, for example, about 3011 m.

Then, this pressure-formed sample with a predetermined shape is heated in a suitable heating furnace at a temperature of 12°C, which is the temperature range after liquid phase crystallization, which is the main reaction in forming cordierite, occurs rapidly.
The treatment is carried out by heating to a temperature in the range of 80°C to 1330°C. At temperatures below 1280°C, the amount of cordierite crystallized changes significantly, and at temperatures above 1330°C, the amount of protoenstatite decreases, resulting in large variations in the required cordierite reactivity ratio: R. In addition, the faster the temperature increase rate at this time, the more advantageous it is for advanced quality control, but if the temperature distribution in the furnace worsens, the variation in data will increase. The temperature was raised within the range of 350° C./hour, thereby making it possible to obtain approximately the same level of data. In particular, it is preferable to set the temperature increase rate in the range of 200° C./hour to 300° C./hour because data can be obtained with good reproducibility.

As the heating furnace to be used, a small electric furnace is suitable because it is easy to use, and it is necessary to select a heating furnace that can provide accurate temperature distribution. By heating the sample to a temperature of 1280°C to 1330°C in such a heating furnace, it is possible to investigate the cordierite reactivity ratio: R of such a sample, but the stability and reproducibility of the data may be affected. From this point of view, preferably 1300°C ~
A heating temperature within the range of 1310°C was adopted, among which 1
Cordierite reactivity ratio: R will be determined for the sample heated to a temperature of 305°C.

Furthermore, the sample heat-treated in this way is rapidly cooled and subjected to X-ray diffraction operation, but such rapid cooling of the sample is generally performed by taking the sample out of the heating furnace and leaving it in the atmosphere. It is preferable to use the electric furnace described above as a heating furnace due to the extraction operation, but if it is not possible to take out the sample due to the furnace structure, it is necessary to remove the sample inside the furnace. There is no problem in answering if the product is rapidly cooled. The cooling rate of the sample in such rapid cooling is generally 300°C/hour or more, preferably 500°C/hour.
/ hour or more.

Next, the heat-treated sample, in other words, the heat-treated press-formed product, is examined by ordinary X-ray diffraction techniques, and its pressed surface, that is, if the sample is an extruded honeycomb structure, is examined by ordinary X-ray diffraction techniques. If the sample is a press-formed product, the plane perpendicular to the pressing direction during press-forming is subjected to X-ray diffraction, and the (310) plane of protoenstatite on the press-forming surface is The diffraction peak intensity: Ip (310) and the X-ray diffraction peak intensity of the (100) plane of cordierite: Ic (100) are determined. More specifically, this
In line diffraction operations, for example, when using an α target on Cu-, the protoenstatite (310) plane with 2θ = 30.8° and the plane parallel to the cordierite C axis with 2θ = 10.3° are used. The cordierite (100) facet peak heights are each measured and are considered as the respective peak intensities. Furthermore, instead of measuring the peak height, the same result can be obtained by determining the peak area, half width, or count number and using it as the peak intensity.

In the present invention, protoenstatite (3
10) From the peak intensity of the plane: Ip (310) and the peak intensity of the (100) plane of cordierite: Ic (100), based on the following formula (I), the cordierite reactivity ratio: R
will be calculated.

R-r p (310) / I c (100)
...... (I) [However, Ip (310): Peak intensity of the (310) plane of protoenstatite Ic (100): Peak intensity of the (100) plane of cordierite] Regarding cordierite crystals, talc and It is known that the C-axis of cordierite crystals crystallizes perpendicularly to the C-axis of kaolinite, and that low expansion properties can be obtained in honeycomb structures only when the cordierite crystals are oriented in a preferable manner. There is. On the pressurized surface of the above sample, due to the orientation of talc and kaolinite, the cordierite (100) plane naturally exists in a more prominent state.For example, even though the reaction process of cordierite is normal, the morphology of the kaolin raw material etc. However, when the orientation of the cordierite crystal becomes abnormal, the strength of the cordierite (100) plane decreases, and the cordierite reactivity ratio of the sample: Ip (310)/Ic (1
00) becomes larger.

The present invention is based on the cordierite reactivity ratio: R determined in this way and the sintered body (
It was completed based on the discovery that the coefficient of thermal expansion of cordierite (ceramic body) shows an extremely good correlation, and the value of this cordierite reactivity ratio (R) By estimating the thermal expansion coefficient of the cordierite ceramic body obtained from the raw material, it was possible to evaluate the quality of the raw material for forming cordierite in a short time and to perform preliminary quality control.

In particular, in the present invention, cordierite reactivity ratio: R
is the following formula (■): 0.30-0.002X (T-1305)...
(II) (where T is the heat treatment temperature of the press-molded sample, which is within the range of 1280°C to 1330°C), the cordierite ceramic obtained based on the value determined at The coefficient of thermal expansion of the body is 1, OX 10
-'/'C or less is evaluated, and when it is smaller than that value, the coefficient of thermal expansion is low, especially in the temperature range of 40 to 800 degrees Celsius, the coefficient of thermal expansion is 1.0X10-'/'C or less. It was evaluated as a raw material for forming cordierite, which gives a light ceramic body.

In this way, if the quality of the raw material for forming cordierite used is controlled according to the evaluation based on the value of the cordierite reactivity ratio (R), the coefficient of thermal expansion of the cordierite ceramic body obtained from the raw material for forming cordierite is determined. is always below a predetermined value, making it possible to stably produce cordierite ceramic bodies with low thermal expansion characteristics.

In addition, when producing a cordierite ceramic body having the estimated target thermal expansion characteristics using such a raw material for forming cordierite, conventional molding operations and firing operations are added.

For example, after adding necessary auxiliary agents to the cordierite-forming raw material to make a batch that can be deformed into a plastic shape, and molding the plasticized batch using ordinary ceramic molding methods such as extrusion pressing and rolling, The dried product is then heated at a heating rate not exceeding 250°C/hour up to a temperature of 1100°C, and at a heating rate of 3°C at a temperature above 1100°C.
By firing at a heating rate of 0°C/hour to 3.00°C/hour and a firing holding temperature in the range of 1350°C to 1440°C for about 0.5 to 24 hours, the objective can be achieved. A cordierite ceramic body is produced which has thermal expansion properties, particularly low thermal expansion properties.

(Effect of the invention) As described above, according to the present invention, by determining the cordierite reactivity ratio: R of a heat-treated product of a predetermined press-molded body sample using a cordierite-forming raw material, Since the thermal expansion characteristics of the cordierite ceramic body obtained by long-term firing of such cordierite-forming raw materials can be easily evaluated, and thereby the quality of such cordierite-forming raw materials can be known, The quality control of raw materials for cordierite has become extremely easy, and the thermal expansion characteristics of molded products or molding clay can be checked in advance in a short period of time. This made it possible to stably produce cordierite ceramic bodies containing

In particular, by controlling the quality of the cordierite-forming raw material so that the cordierite reactivity ratio: R of the cordierite-forming raw material, which is the starting raw material, is always equal to or less than the value shown by the above formula (II), It has low thermal expansion characteristics, in other words, the thermal expansion coefficient is 1. OX 10-h
The present invention can be manufactured as a cordierite ceramic body having a characteristic of /''C or less, and thus can be advantageously applied to the manufacture of ceramic honeycomb catalyst carriers for various exhaust gas purification devices, especially automobile exhaust gas purification devices.

(Examples) In order to clarify the present invention more specifically, some examples of the present invention will be shown below, but the present invention shall be interpreted in an equivalent and restrictive manner by the description of such examples. It goes without saying that this is not the case.

It should be noted that the present invention can be implemented in various embodiments in addition to the detailed description of the present invention described above and the following examples, and therefore, those skilled in the art will be able to carry out the present invention without departing from the spirit of the present invention. It should be understood that all of the various embodiments that can be implemented based on knowledge fall within the scope of the present invention.

Example 1 Using raw materials with chemical compositions shown in Table 1 below, cordierite forming raw materials A-E were prepared at the raw material mixing ratios shown in Table 2 below, and 100% of the cordierite forming raw materials were prepared. After adding 3 parts by weight of methylcellulose as an organic binder per part by weight and kneading by adding an appropriate amount of water, the mixture was molded into 102 wφ according to a known extrusion method.
Various honeycomb structures X (CTE evaluation samples) having a cell structure having a shape of 89 mjL, a rib thickness of 150 μms, and a cell number per square centimeter of approximately 62 were manufactured. In addition, by the same extrusion molding method, 20mm x 3Q@@X4Qw was made from each cordierite raw material.
A block-shaped honeycomb structure Y (cell opening surface is a surface of 20 cranes x 30 cranes) with a cell structure having a size of 81,508 m in rib thickness and approximately 62 cells per square centimeter. R evaluation sample) was manufactured.

Next, the coefficient of thermal expansion of the sintered body obtained by firing the honeycomb structure X at 1400° C. for 8 hours was measured, while the various cordierite reactions of the various heat-treated products of the honeycomb structure Y were measured. Sex ratio:
R was measured and the results are also shown in Table 3 below.

In addition, honeycomb structure X as these evaluation samples,
All of the raw materials constituting the cordierite forming raw materials used for molding Y, except for talc (C), have a diameter of 105 μm.
The sieve bathed was used. As for talc (C), talc (a) was finely ground and passed through a 44 μm sieve. Moreover, kaolin (b) has a large thickness in the kaolinite C-axis direction, and has a loft in which the kaolinite C-axis has poor orientation in the direction perpendicular to the pressing surface during extrusion molding.

In addition, the recycled raw material is obtained by crushing an unfired honeycomb molded product, and depending on the respective crushing conditions, the recycled cordierite forming raw materials (a) to (d) The one prepared as follows was used.

Furthermore, the cordierite reactivity ratio: R is such that the honeycomb structure Y formed from each of the cordierite forming raw materials A to E is heated at a rate of 200°C/hour in an electric furnace for 12 hours.
The product obtained by heat treatment by raising the temperature to various temperatures between 80℃ and 1330℃, and then taking it out from the electric furnace at the maximum temperature reached and quenching by leaving it in the atmosphere (heat treatment) Regarding sample),
The lip surface parallel to the extrusion direction of the honeycomb structure (30n
X40n plane) was evaluated according to the usual X-ray diffraction method. That is, the measurement surface of the lip was polished, the polished surface was irradiated with X-rays, and the peak height of the protoenstatite (310) plane at 2θ = 30.8' and the peak height of the protoenstatite (310) plane at 2θ = 30.8'
, 3' of the cordierite (100) plane were measured, and the cordierite reactivity ratio: R was calculated.

As is clear from the results in Table 3, the cordierite reactivity ratio: R and the thermal expansion coefficient of the sintered body (cordierite ceramic body) are approximately proportional. Reactivity ratio in heat treated product: R is 0.3
If it becomes larger, the coefficient of thermal expansion of the sintered body will also be 1. Ox 1
It is recognized that the value is 0-'/'c or more.

In addition, Fig. 1 shows a normal R evaluation sample obtained using a cordierite forming raw material that gives a low coefficient of thermal expansion, and an abnormal R evaluation sample obtained using a cordierite forming raw material that gives a sintered body with a high coefficient of thermal expansion. , 1200℃~13
The peak intensity of the (310) plane of protoenstatite at various temperatures between 30 ° C.: Ip (310) and the peak intensity of the (100) plane of cordierite: Ic (100
) are shown in the X-ray diffraction peak height, respectively. As is clear from this Figure 1, the abnormality R
In the evaluation sample, cordierite crystallizes quickly, and is therefore suppressed by the solid phase crystallized cordierite.
It is recognized that the liquid phase crystallization temperature has shifted to a high temperature and the balance with the amount of intermediate product crystallization has been disrupted.

Example 2 Using the raw materials having the chemical compositions shown in Table 1 above, various cordierite forming raw materials A-1 to 3, E-1 to 3, F to (3), and in the same manner as in Example 1, various honeycomb structures X and Y (CTE evaluation sample and R evaluation sample) were molded. The thermal expansion coefficient of the sintered body from the honeycomb structure Y, and the cordierite reactivity ratio: R of the heat-treated product from the honeycomb structure Y were measured, and the results are shown in Table 5 below. Ta.

For the R evaluation samples, heat treatment was performed with the electric furnace take-out temperature (maximum heat treatment temperature) at 1305° C. and at various heating rates in the electric furnace.

Example 3 From the uniform powder mixture of the cordierite forming raw material A-I used in Examples 1 and 2 at various mixing ratios, 5 grams each were collected and pressed into a 5 m1 x 20 crane plate shape at a pressure of 300 kg/cd. Molded. Next, the various press-formed products obtained were heated in an electric furnace under the conditions of a temperature increase rate of 300°C/hour, a take-out temperature (maximum heat temperature') of 1305°C, and air cooling. Using the heat-treated product, the cordierite reaction ratio: R was determined in the same manner as in Example 1. At that time, the X-rays were irradiated from the perpendicular direction to the pressurized surface of the heat-treated press-formed product, which was 15 mm x 20 n+. ” cordierite (
100) Measure the height of each plane and calculate the reactivity ratio:
I rolled an R.

The obtained results are shown in Table 6 below, and the results of Example 1 and (
The coefficient of thermal expansion of the sintered body obtained by firing at 1400° C. for 8 hours is also shown.

Table 6 Also, in order to know the relationship between the cordierite reactivity ratio: R and the coefficient of thermal expansion of the product fired at 1400°C for 8 hours, the measured values obtained in each of the above examples are plotted in Figure 2. . As is clear from this Figure 2, the obtained cordierite reactivity ratio: R and the normal firing method (1400℃
x 8 hours) has an extremely good correlation with the coefficient of thermal expansion of the sintered body, and roughly speaking, when the reactivity ratio: R at 1305°C is 0.3 or less, 1. Ox
It is observed that a coefficient of thermal expansion of less than 10-"/"c (40-800°C) is achieved.

[Brief explanation of drawings]

Figure 1 shows the relationship between the heat treatment temperature and the X-ray diffraction peak heights of the (310) plane of protoenstatite and the (100) plane of cordierite in each evaluation sample, determined in Example 1. FIG. 2 is a graph showing the relationship between the cordierite reactivity ratio: R determined in each example and the thermal expansion coefficient. Figure 1 Heat treatment temperature ('C) Figure 2 (1305°C extraction) Procedure chief Masayoshi Ho (voluntary) 1. Indication of the case 1986 Patent Application No. 50935 2, Name of the invention Cordierite-forming raw material 3, Person making the amendment Relationship to the case Patent applicant name (406) Nippon Insulator Co., Ltd. 4, Agent 0
450 6. Contents of amendment (1) Akira tag, page 10, line 3, “Alumina: 34
~4B! i! ffi%J "Alumina: 30-44
Corrected to ``Multiple volumes%''. (2) “Alumina; 35-4
5311ffi%” to “Alumina: 32-41%”
Correct. (3) - Correct "irradiated from a direction perpendicular to the surface" in line 13 of page 32 to "irradiated onto surface d". that's all

Claims (3)

[Claims] (1) A cordierite-forming raw material powder that gives a predetermined cordierite ceramic body by firing, and the raw material powder is press-molded so that the cordierite reactivity ratio: R expressed by the following formula is 0.3 or less. A cordierite-forming raw material characterized in that it provides a body heat treated product. R=Ip(310)/Ic(100) [wherein, Ip(310) and Ic(100) are
X of the (310) plane of protoenstatite and the (100) plane of cordierite on the pressure-molded surface of the heat-treated press-molded product obtained by heat treatment at a temperature of 1300°C to 1310°C, respectively.
It is the line diffraction peak intensity] (2) The cordierite-forming raw material according to claim 1, wherein the molded body subjected to the firing is a honeycomb structure. (3) The cordierite ceramic body is 1.0×
The cordierite-forming raw material according to claim 1 or 2, which has a coefficient of thermal expansion of 10^-^6/°C or less.