JPS6374952A - Manufacture of ceramic products - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] A0 Purpose of invention (1) Industrial application field The present invention relates to a method for manufacturing ceramic products.

(2) Conventional technology Conventionally, when manufacturing this type of product, a molded body is obtained using a mixed powder in which sintering aid powder, etc. is dispersed in ceramic powder, and then the molded body is heated under normal pressure or high pressure. A method has been adopted in which a sintered body is obtained by sintering, and then the sintered body is machined.

(3) Problems to be solved by the invention However, since the sintered body obtained through the above process has a large hardness, it is difficult to process it with anything other than a diamond tool, and it is difficult to process it using a diamond tool. However, there is a problem in that it requires a lot of processing time and the productivity of ceramic products is poor.

In view of the above, the present invention aims at streamlining the processing work by obtaining a calcined viscous body having a predetermined strength and performing machining on the calcined body, thereby improving the productivity of ceramic products. It is an object of the present invention to provide the above-mentioned manufacturing method.

B0 Structure of the Invention (1) Means for Solving the Problems The present invention provides a method for adding a halide to ceramic powder that exhibits a pre-sintering effect on the ceramic powder at a temperature lower than the sintering temperature of the ceramic powder. A step of obtaining a compact using a mixed powder in which powder is dispersed, and then pre-sintering the compact at the temperature lower than the sintering temperature to obtain a pre-sintered compact;
a step of performing machining on the temporary sintered body to obtain an intermediate product;
and a step of sintering the intermediate product at the sintering temperature:
It is characterized by using

(2) Effect Due to the pre-sintering effect of the halide, it is possible to obtain a pre-sintered body having strength that can withstand machining and hardness that allows machining with ordinary cemented carbide tools.

Therefore, machining of this pre-sintered body can be performed efficiently, and productivity of ceramic products can be improved.

The intermediate product obtained by the machining process is finally subjected to sintering treatment, so it has high strength and large hardness,
Furthermore, ceramic products with good dimensional accuracy can be obtained.

(3) Example Ceramic powder forms the main body of a ceramic product,
As this kind of powder, Sis N with a diameter of 0.1 to 1 μm is used.
4, SiC, Zr0t% TiN, and mixed powders thereof are applicable.

Halide powders that exhibit a pre-sintering effect on ceramic powders at temperatures lower than their sintering temperatures include:
MgF, with a diameter of 0.1-0.5 pm.

Fluoride powder such as CaF, BaF, Mg(1, CaC
At least one selected from chloride powders such as 4'z, BaC1z, AJClls, YCIs, etc. is applicable. In this case, AlCl3 has AlIC11! +3-X
)(OH)x, and YCl3 has Y C7! +3-
Xl(OH)x is included. It is believed that the preliminary sintering effect is caused by activation of the ceramic powder by the halide.

In addition to the above-mentioned preliminary sintering effect, halides also have the effect of preventing coarsening of the crystal grains of ceramic powder and suppressing variations in strength. This is thought to be based on the following reasons. . That is, the coarsening of the grains of ceramic powder is due to the fact that some of the ceramic powder merges with its surrounding matrix and grows into one large grain during sintering, and therefore the coarsening of the ceramic powder If a halide having physical properties that is not incorporated into the crystal grains exists at the grain boundaries of the ceramic powder, the merging of the matrix will be suppressed.

If necessary, a sintering aid powder that exhibits a sintering effect at the sintering temperature of the ceramic powder is used. This kind of powder includes AIt, 03, YiO with a diameter of 0.1 to 1 μm.
This includes individual powders such as s, Mg0SS i Ot, and mixed powders thereof.

The blending amounts of the ceramic powder, halide powder, and sintering aid powder are as follows: Ceramic powder: 85 to 97% by weight Halide powder: 0.1 to 2.5% by weight Sintering aid powder: 15
% by weight or less.

The reason for limiting the blending amount of each powder as described above is as follows. In the case of halide powder, the blending amount is 0.
If the content is less than 1% by weight, the temporary sintering effect of the halide cannot be sufficiently obtained, so the strength of the temporary sintered body decreases, and there is a risk that the temporary sintered body will collapse during machining. On the other hand, if it exceeds 2.5% by weight, the halide becomes excessive and the strength of the pre-sintered body decreases due to this. Furthermore, when sintering an intermediate product, halide sublimes just before reaching the sintering temperature, but if there is an excess of halide powder, it remains in the ceramic product after sintering and causes a decrease in its strength. becomes.

This is because, in the case of the sintering aid powder, even if the blending amount exceeds 15% by weight, the sinterability of the ceramic powder will not change to that extent.

When obtaining a molded body using a mixed powder consisting of the ceramic powder, halide powder and, if necessary, sintering aid powder, various molding methods such as slip casting, pressure molding, and injection molding can be used. It will be done. Molding pressure is 25
~150 MPa is appropriate.

Further, the pre-sintering conditions for obtaining a pre-sintered body from the molded body are 1200-1500°C and 0.5-5 hours. Due to this preliminary sintering treatment, the molded body exhibits a linear shrinkage rate of 1 to 5%.

The bending strength of the temporary sintered body is 3 to 30 MPa, the Vickers hardness Hm is 200 to 600, and the density is 1.8 to 2.
．． 18/am', and the porosity is 25-40%.

In this way, the pre-sintered body is a porous body, and the growth of crystal grains such as ceramic powder is in the very early stage of sintering.
Because it has relatively low hardness and a certain level of strength, it has good machinability in lace processing, drilling, etc.
In order to obtain the cutting speed of 0 m/win and to achieve the best machinability without collapsing during machining, the Vickers hardness Hmv of the pre-sintered body should be set to 300 to 5.
It is recommended to set it to 00.

As a sintering method for the intermediate product obtained by machining, a pressureless sintering method, a hot press method, a HIP treatment (hot isostatic pressing treatment) using a capsule method, etc. are adopted.

Sintering conditions vary depending on the ceramic powder, for example 3
1500-1750°C when mainly composed of t3Na
1600 for more than 30 minutes when using SiC as the main component.
~2200°C for 30 minutes or more, and in the case of ZrO2 as the main ingredient, 1400~1600°C for 30 minutes or more.

[Example I]

Ceramic powder 5f3N4 with diameter 0.1-1 μm 91.5% by weight T i N 5.0% by weight Diameter 0.1
~0.5μm halide powder CaClz
0.5% by weight sintering aid powder y, o with a diameter of 0.1-1 μm, 2.0% by weight Aβ-rich Os
A mixed powder was obtained by mixing 1.0% by weight, and a pressure molding method was applied using this mixed powder to a molding pressure of 100%.
At MPa, a cylindrical molded body 1 having a diameter of 40 fins and a length of 40 fins shown in FIG. 1 is obtained.

The dried compact 1 was placed in a sintering furnace, N3 gas was passed through the furnace at a rate of 30 ml/a+in, and the temperature inside the furnace was raised to 650°C at a rate of 15°C/win. Hold at temperature for 45 minutes, then increase to 1200'C at 20°C/
Preliminary sintering treatment is performed at 1200° C. for 2 hours by raising the temperature under sin condition.

The bending strength of the temporary sintered body is 200 MPa, and the Vickers hardness Hmv is 300.

The preliminary sintered body is drilled using an ordinary cemented carbide drill to obtain an intermediate product 3 in which a through hole 2 with a diameter of 23 m is formed in the center as shown in FIG.

It has been confirmed that this intermediate product 3 has no defects such as chipping or cranking during processing, and the processing speed is approximately the same as that of aluminum alloy, chilled cast iron, etc.

The intermediate product was heated to 90°C at 1650°C under the application of HIP treatment.
A ceramic product is obtained by a sintering process for 1 minute.

In this case, the intermediate product exhibits a linear shrinkage rate of 8%, and therefore the dimensional accuracy of the ceramic product is good. The bending strength of ceramic products is 0.7 GPa (IGPa-
IXIO3MPa), Vickers hardness Hm v is 16
50, and it has been confirmed that ceramic products have high strength and great hardness.

If necessary, the ceramic product is subjected to finishing processes such as polishing and polishing, but such finishing processes can be easily performed even after sintering.

[Example ■]

Ceramic powder with a diameter of 0.1-1 μm 5isNa 86.5% by weight TiN
10.0% by weight Halide powder Ca C1,0.5% by weight with a diameter of 0.1-0.5 μm Sintering aid powder YtOs with a diameter of 0.1-1 μm 2.0% by weight AIl*Os
1.0% by weight to obtain a mixed powder,
Using this mixed powder, a slip casting method is applied to obtain a plate-shaped molded body 4 having a length of 200 mm, a width of 60 mm, and a thickness of 10 m as shown in FIG.

The dried compact 4 was placed in a sintering furnace, N gas was passed through the furnace at a rate of 30 ml/win, and the temperature inside the furnace was raised to 650°C at a rate of 15°C/+min. Hold at that temperature for 45 minutes, then 20°C/20°C up to 1200°C.
Preliminary sintering treatment is performed at 1200° C. for 2 hours under the conditions of s+in.

The bending strength of the temporary sintered body is 350 MPa, and the Vickers hardness is H.
mv is 350.

The pre-sintered body is cut into a third sintered body using an ordinary cemented carbide cutter.
Cut as shown by the chain line in the figure to obtain a material 60 m long, 40 ++ n wide, and 10 mm thick. As shown in FIG. 4, using the force lid, open the material 5 in a V shape with a width of 51-1 and a depth of 20 mm.
Three shaped notches 6 are formed to obtain an intermediate product 7.

It has been confirmed that this intermediate product 7 has no defects such as chipping or cranking during processing, and the processing speed is approximately the same as that of aluminum alloy, chilled cast iron, etc.

The intermediate product was heated to 90°C at 1650°C under the application of HIP treatment.
A ceramic product is obtained by a sintering process for 1 minute.

In this case, the intermediate product exhibits a shrinkage rate of 10%, and therefore the dimensional accuracy of the ceramic product is good. The bending strength of ceramic products is 0.80 Pa (IGPa-I
XIO3MPa), Pinkers hardness Hmv is 180
0, and it has been confirmed that ceramic products have high strength and large hardness.

Similar to Example 2 above, the ceramic product is subjected to finishing processing such as polishing if necessary, but such finishing processing can be easily performed even after sintering.

[Example ■]

Ceramic powder 5tsNa 80-95% by weight TiC5 with a diameter of 0.1-1 μm
, O ~ 15.0% by weight Halide powder with a diameter of 0.1 ~ 0.5 μm M g F
t 0.1~2.5% by weight Diameter 0.1~
1 μm sintering aid powder YzOs 4.0% by weight or less M g O
A wide variety of mixed powders were obtained with varying blending amounts within the range of 2.0% by weight or less, and a pressure molding method was applied using these mixed powders to obtain a molding pressure of 100% by weight.
At MPa, a large number of molded bodies of #170fi, width 20n, and thickness 5M were obtained.

Each dried compact was placed in a sintering furnace, N2 gas was passed through the furnace at a rate of 25 ml/win, and the temperature inside the furnace was raised to 650°C at a rate of 15°C/win. Hold at that temperature for 45 minutes, then 20°C/+ up to 1200°C
A temporary sintering process is performed at 1200°C for 2 hours under sin conditions. Through this temporary sintering process, each compact exhibits a linear shrinkage rate of 1 to 2%, and each temporary sintered body The density of is 2.0
~2.2 g/am3.

Figure 5 shows the relationship between the blending amounts of MgFt and Tic in each pre-sintered body and the bending strength of each pre-sintered body, with lines a,
”-c, the amount of Tic added is 5.0°10.0.15.
This applies to each case of 0% by weight.

It is clear from FIG. 5 that the bending strength of the pre-sintered body improves as the amount of Tic added increases.

The Vickers hardness Hmv of each pre-sintered body corresponding to the line alxc is 300-500.400-700.
It is 700-1000.

When each pre-sintered body was subjected to mechanical processing such as lace processing and drilling to produce an intermediate product, the pre-sintered body had a
Bending strength of M P a or higher and Vickers hardness of 300 or higher) (m V indicates good machinability;
It has also been confirmed that a normal intermediate product without cracks etc. can be obtained.

In FIG. 5, the reason why the bending strength of the pre-sintered body improves as the blending amount of TiC increases is that oxygen, which is an impurity in TiC, sufficiently reacts with MgFt to form MgTj
Titanium is easily oxidized and reduced, and Ti
This is thought to be due to the fact that a substitution reaction such as C-=TiN progresses during calcination.

Also, MgFz (the same applies to other halides)
is an oxide (Y) as a sintering aid powder at the pre-sintering temperature.
It has the effect of reacting with zOs, MgO), TiC, etc. and activating them, thereby obtaining a high-strength pre-sintered body, but when the amount of MgFt blended is small, The anionic effect of MgFz is insufficient, while when the amount of MgF is large, MgFz
Since the amount of TtCl exceeds the recrystallized TtCl, it is thought that the bending strength of the pre-sintered body tends to decrease.

TiC5,011 corresponding to line al+ b+ in Figure 5
0,0% by weight of each intermediate product under the application of HIP treatment.
A ceramic product is obtained by sintering at 700° C. for 90 minutes.

In this case, each intermediate product exhibits a linear shrinkage rate of 10-12%, and therefore the dimensional accuracy of each ceramic product is good. In addition, the density of each ceramic product is 3.1 to 3.2 g/c
+a', which is confirmed to be 93% or more of the theoretical density.

Figure 6 shows the relationship between the blending amount of M g F t and TiC in ceramic products and the bending strength of each ceramic product, and the line a@+bt indicates that the blending amount of TiC is 5.0.1
This applies to each case of 0.0% by weight.

As shown in FIG. 6, the bending strength of the ceramic product improves as the amount of T i C added increases; however, when the amount of Tic is kept constant, for example, for line a, the amount of Mgl''2 added is 0. When set to 1-2.0% by weight, the bending strength is 0.7-
1. IGP a can be obtained, and practically sufficient strength can be ensured. It can also be seen that the bending strength of ceramic products shows a similar tendency to that of pre-sintered bodies.

Further line at+b! The Vickers hardness of each ceramic product corresponding to ) l m v is 1500.17 respectively.
It is 00.

C0 Effects of the Invention According to the present invention, a pre-sintered body obtained based on the pre-sintering action of a halide is machined to obtain an intermediate product, and the intermediate product is subjected to a sintering treatment, so that it has high strength. It is possible to efficiently produce ceramic products with high hardness and good dimensional accuracy.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing an example of a molded product, Fig. 2 is a perspective view showing an example of an intermediate product, Fig. 3 is a perspective view showing another example of a molded product, and Fig. 4 is a perspective view showing another example of an intermediate product. A front view showing an example, FIG. 5 is a graph showing the relationship between the amount of MgF2 mixed in a pre-sintered body and bending strength, and FIG.
It is a graph which shows the relationship between the compounding quantity of gFt and bending strength. 1.4...Molded object, 3.7...Intermediate product license application Person: Honda Motor Co., Ltd. Agent Patent attorney: Ochiai Key box 1 Figure 2 Figure 3 Figure 5 Content of MgF2 (Weight'/, ) Figure 6

Claims (1)

[Claims] A molded body is obtained using a mixed powder in which a halide powder that exhibits a pre-sintering effect on the ceramic powder is dispersed in a ceramic powder at a temperature lower than the sintering temperature of the ceramic powder, and then the molded body is obtained. a step of pre-sintering at the temperature lower than the sintering temperature to obtain a pre-sintered body; a step of machining the pre-sintered body to obtain an intermediate product; and a step of sintering the intermediate product. A method for producing a ceramic product, characterized by using a step of sintering at a high temperature.