JPS60197839A - Jig for sintering ceramics and its production - Google Patents

Abstract

PURPOSE:To produce a jig for sintering ceramics which is free from deformation at a high temp. by subjecting an Mo alloy contg. an adequate amt. of a high melting oxide to working such as forging at an adequate temp. then forming the alloy and subjecting further the alloy to heat treatment at the secondary recrystallization temp. or above. CONSTITUTION:An Mo alloy contg. 0.05-5.0wt% >=1 kinds among high melting oxides such as ZrO2, Y2O3, MgO, etc. is subjected to forging or rolling at >=80% working ratio in the temp. region from a room temp. up to the primary recrystallization temp. or below and is then worked to the shape of a jig. The resultant precursor of the jig is subjected to a heating treatment in the temp. region from the temp. higher by 100 deg.C than the secondary recrystallization temp. up to <=2,200 deg.C, by which the jig 1 for sintering ceramics is obtd. The above-mentioned jig 1 for sintering ceramics is obtd. The above-mentioned jig 1 consisting of the Mo alloy grown with the flat, slender and large secondary recrystallization grains and having excellent high-temp. strength is obtd. by the above-mentioned heat treatment. The jig 1 is usable for sintering ceramics after said jigs are superposed into several steps.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a jig made of a molybdenum alloy used for sintering ceramics and a method for manufacturing the same, and more particularly, to a jig made of a molybdenum alloy and a method for manufacturing the same, which is used for sintering ceramics. - Concerning jigs and their manufacturing methods.

[Technical background of the invention and its problems]

Generally, various ceramics are sintered by placing a press-molded ceramic powder compact on a shelf, usually made of graphite, and heating it in an inert atmosphere at 1500 to 1800 DEG C.

However, graphite has low mechanical strength.

There is a problem in that the total weight of the ceramic powder molded bodies that can be placed cannot be made too heavy, which increases productivity during sintering.

For this reason, recently, sintering jigs made of molybdenum plates, which have high strength and heat resistance at high temperatures, have been used.

Such molybdenum plates are generally manufactured as follows. That is, first, an ingot made by sintering molybdenum powder is subjected to hot working such as forging and rolling at a high temperature to form a root. This plate material can be put to practical use as a jig as it is, or it can be annealed to remove processing distortion at a temperature below the secondary recrystallization temperature 1, usually in the temperature range of 800 to 1200°C, and then subjected to secondary forming 7JO processing. It has been put into practical use after undergoing this process.

However, when the molybdenum plate obtained by such a method is used as a ceramic sintering jig, the following disadvantages arise.

It is generally used for jigs in a temperature range of 1500 to 1800°C. And the secondary recrystallization temperature of molybdenum is about 1200
It is ℃. Therefore, secondary recrystallized grains grow in molybdenum jigs during use, and the embrittlement caused by coarsening causes the jigs to break. Furthermore, thermal fatigue due to repeated heating and cooling cycles and creep phenomenon occur during high-temperature use.

The jig may be significantly deformed.

For example, in the case of a jig used in an automated line for sintering ceramic substrates, if the above phenomenon occurs, the ceramic substrate may fall from the jig or be deformed, and in extreme cases, The molybdenum jig will come into contact with the ceramic substrate, making it impossible to store the ceramic substrate. Then, it becomes impossible to use it for a long period of time.

Thus, when using a molybdenum plate material as a jig for sintering ceramics, a molybdenum material that has excellent high-temperature strength and does not deform is required.

(Object of the invention) The present invention provides a method for sintering ceramics to
The above-mentioned deformation and other phenomena do not occur.

The purpose of the present invention is to provide a ceramic sintering jig made of a molybdenum alloy with excellent high-temperature strength and a method for manufacturing the same.

[Summary of the invention]

The ceramic sintering jig of the present invention is characterized by a core made of a molybdenum alloy with excellent high-temperature strength, and the manufacturing method thereof is as follows.

A molybdenum alloy containing 0.05 to 5.0% of one or more high melting point oxides is forged or rolled at a processing rate of 80% or more in the temperature range from room temperature to less than the primary recrystallization temperature. First step of processing; Second step of forming the obtained workpiece into a jig shape; The obtained jig precursor is heated from a temperature 100°C higher than the secondary recrystallization temperature to 2200°C or less It is characterized by consisting of @30 steps of performing heat treatment in a temperature range of .

The jig of the present invention is made of a molybdenum alloy manufactured by the method described below. A jig can take the shape of camphor trees, but one example is
A plate-shaped body with both ends bent as shown in FIG. 1 is common. The folded part supports the part from below and lifts the board part,
A ceramic powder molded body is placed on the plate surface and used. It is preferable that the direction of the secondary recrystallized grains to be grown by the heat treatment described below is in a state where they straddle the fulcrums of the bent portions.

The jig of the present invention is manufactured through the following steps. In the first step, one or more types of high melting point oxides are mixed at a temperature of 0.05 to 5.
This is a process of forging or rolling a molybdenum alloy containing 0% by weight at a processing rate of 80% or more in a temperature range from room temperature to less than the primary recrystallization temperature. First, the starting material is a sintered body obtained by sintering molybdenum powder to which one or more high melting point oxides are added by a conventional method.

This high melting point oxide is a component added in order to cause the structure of the secondary recrystallized grains grown in the molybdenum material by the heat treatment described below to grow long and narrow in a direction perpendicular to the processing direction described later.

Specifically, zirconium dioxide (ZrO2), yttrium oxide (Y2O2), lanthanum oxide CLa203
).

Examples include magnesium oxide (MgO). These may be used alone or in an appropriate combination of two or more.

These high melting point oxides are usually used in the form of powders with a particle size of 005 to 1 μm. If the content of molybdenum in the matrix is less than 0.05%, the effect is small and even if the heat treatment described below is applied, the shape of the secondary recrystallized grains will be hexagonal cylindrical crystal grains. Therefore, it does not contribute to the improvement of high-temperature strength, and if it exceeds 5.0% by weight, processing in the first and second steps becomes extremely difficult.

In the present invention, firstly, such a molypdenoid alloy f
t Cold 7JO processing is performed by forging or rolling in a temperature range from room temperature to less than the primary recrystallization temperature. If the temperature of the processing + AI U at this time exceeds the primary mother crystal temperature, subdalein will occur during processing, making it impossible to develop the processed fiber structure and arrange the high melting point oxide particles along the processed # and #l fiber structures. II such as
, a problem arises. Also forged.

For rolling, it is best to apply the 1st method.

By this processing, the structure of the molybdenum alloy is stretched in the direction perpendicular to the processing direction and crushed in the processing direction KtX, so that the structure is arranged into a fibrous structure as a whole. At this time, most of the leJ powder of high melting point oxide added is arranged along the above-described fibrous structure. In some cases, it is dispersed within the fibrous structure to increase the strength of the structure.

In the present invention, the processing rate of this cold working is 80 inches or more. Here, the machining rate is a percentage display for one shift, which is the decrease in the cross-sectional area of the molybdenum material before and after machining divided by the cross-sectional area before machining, and it means that the larger +i is, the more advanced the machining is. do.

If the processing rate is less than 80% (in the case of the back), the powder of the melting point oxide is not arranged in the era name along the fibrous structure described above, and the secondary recrystallized grains become hexagonal during the heat treatment described below. It easily forms an axial crystal structure.Therefore, when used at high temperatures, iz, = r
As mentioned above, phenomena such as abnormal deformation and intergranular cracking due to grain boundary cracking are more likely to occur in molybdenum materials. It is desirable that the processing rate is 90% or more. However, since it is not possible to achieve a processing rate of 100%, in the present invention, the processing rate is 100%.
00chi doesn't meet.

The second step is a step in which the molybdenum plate processed in the above steps is subjected to a molding process to form the entire plate into the shape of a jig to produce a jig precursor. For example, in manufacturing the jig shown in FIG. 1, both ends of the workpiece obtained in the first step are bent as shown in the figure.

At this time, it is preferable to bend both ends of the fibrous tissue in the direction in which it extends, since this can effectively support the surface of the board. Incidentally, during such folding processing, it is effective to slightly heat the part to be processed, since this will prevent 1a tearing and cracking at the time of processing.

The third step is a step in which the obtained jig precursor is subjected to heat treatment in a temperature range from 100° C. higher than the secondary recrystallized grain formation to 2200° C. or lower. the result.

Flat, elongated, and large secondary recrystallized grains grow in the precursor.

If the heating temperature at this time is below the above temperature.

In the first place, the growth of secondary recrystallized grains is insufficient, and as a result, the growth of unstable crystal grains progresses in the molybdenum jig when used at high temperatures, resulting in variations in thermal fatigue strength and IJ +1 strength.

However, when the temperature during heat treatment becomes higher than 2200°C, elongated and large secondary recrystallized grains grow excessively in a zigzag pattern, resulting in a grain boundary state similar to an equiaxed crystal structure. When used as a material, abnormal deformation and grain boundary cracking are likely to occur due to a decrease in single-grain boundary dimensions and high-temperature strength, and damage due to embrittlement.

This tends to lead to cracking phenomena.

Note that in the present invention, the forged or rolled workpiece is directly subjected to the heat treatment described above, but after the processing, annealing is performed once to remove distortion at a temperature lower than the secondary recrystallization temperature. After that, the above heat treatment may be completed.

The jig of the present invention may be a single jig as illustrated in FIG. 1, but in one example, as illustrated in FIG. Color 3 fixed with
It may also have a multi-tiered structure in which it is stacked on top of the other.

In the case of a jig with such a multi-stage structure, the space inside the furnace can be used effectively, and each jig plate la, lb, l
It is useful because different types of ceramic powder compacts can be placed on c and ld, respectively.

(Example of the invention) Four types of mixed powder samples were prepared by mixing MO powder and high melting point oxide powder in the proportions shown in Table 1 (1% by weight). Regarding sample 1.2. Samples 3 and 4 were mixed for 20R in Botlow 2, and samples 3 and 4 were mixed with each sol and Mo2 powder for 5 hours using a stirrer, and then heated and dried at 120'C.Sample 5 was a comparative example containing only Mo powder.

Table 1 Each of these mixed powders was molded under a pressure of about 2 ton/i, and the resulting molded body was sintered in a hydrogen furnace at 1830° C. for 9 hours. For comparison, a sintered body containing only MO was also produced under similar conditions.

These sintered bodies were forged at 1100-1400'C and rolled at a temperature below 1100°C to achieve a cold working rate of 9.
5% and a plate material with a thickness of 21EII. Note that from the molybdenum alloy of sample 1, a plate material (thickness 2) with a cold working rate of 75% was also manufactured.

A jig plate having the shape shown in FIG. 1 (length 130M, width 20011A) was formed from these plate materials.

Each jig plate was subjected to heat treatment as shown in Table 2.

Table 2 Note that to prevent deformation during heat treatment, a flat thick tungsten plate is placed on the surface of each jig plate, and two of these jig plates are used to create the multi-stage structure illustrated in Figure 2. The sintering jig was assembled.

A 0.75Ky tungsten disk (diameter 10011B) is placed on the center plate surface of each jig plate, and in that state
A heating/cooling cycle was repeated 20 times, in which the sample was left in a hydrogen stream at 0° C. for 10 hours and then left at room temperature for 1 hour. Every four cycles, the warpage of the central part of the jig plate 1 with respect to the four corners was measured for each two pieces, and the average value of the two pieces was calculated. The distance between the tungsten disk and the lower surface of the jig plate l placed thereon was 109.

The results are shown in FIG. 3 in relation to the number of heating and cooling cycles. In the figure, curves a, b, c, and d represent Examples 1 and 2, respectively.
, 3.4 represents the case of the jig plate.

Curve #e represents Comparative Example 41, curve f represents Comparative Example 31, curve hi- represents Comparative Example 11, and curve hi- represents the state of the jig plate of Comparative Example 2.

As is clear from the figure, the jig plates of Comparative Examples all had large warpage, and Comparative Example 4. Comparative example 3. For each jig plate of Comparative Example 2, the test was performed 4 times and 8 times.

Although the jig plate of the present invention comes into contact with one tungsten disk after 16 heating/cooling cycles, none of the jig plates of the present invention deform beyond 8 circles.

[Effects of the Invention] As is clear from the above explanation, the jig manufactured by the present @mei method has a sintering temperature of 15, which is the sintering temperature of the ceramic powder compact.
Even in the temperature range of 00~1800℃.

Since the deformation is very small and it maintains a stable state for a long time, for example, when used as a sintering jig in an automated line, it not only has a long service life but also reduces the number of maintenance inspections. This makes it possible to increase the operating efficiency of the furnace.

Furthermore, since this jig has high high-temperature strength, by stacking the jig in a multi-stage structure, it becomes possible to effectively utilize the space inside the furnace during sintering of the ceramic powder compact.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one example of the jig of the present invention, and FIG.
This is a jig with a multi-tiered structure made by stacking the jigs shown in the figure. Third
Figure ij: A diagram showing the warpage of each jig plate described in the other examples. Figure 2

Claims (1)

[Claims] 1. A ceramic sintering jig made of a molybdenum alloy with excellent high-temperature strength. 2. A jig for sintering ceramics according to claim 1, wherein the jig is stacked in multiple stages. 3 High melting point oxide 1 or 2& or more is 0.05 to 5.
The first step is to forge or roll a molybdenum alloy containing 0 wt 1% at a processing rate of 80% or more in the temperature range from room temperature to primary recrystallization heating; A second step of performing a shape forming process; A third step of subjecting the obtained jig precursor to a heat treatment in a temperature range from 100°C higher than the secondary recrystallization temperature to 2200°C or less; A method for manufacturing a ceramic sintering jig, characterized by: