JPS5997575A - Manufacture of silicon nitride sintered body - 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] The present invention relates to a novel method for manufacturing silicon nitride-based sintered bodies.

Silicon nitride-based sintered bodies have been used in many applications including high-temperature electrical insulation materials and electronic component materials. The conventional manufacturing method for silicon nitride-based sintered bodies uses Si powder and Si, N
Atmospheric pressure sintering method A~ is a method in which only the q-grain mixed powder or Si powder is molded together with a binder such as acrylic resin, and then heated to about 1400 to 1450°C in a nitrogen atmosphere to perform nitriding reaction sintering. The phrase was common. However, since most of the binder material in the nitrided body produced by the conventional method is vaporized and disappears during the heat treatment process,
It was difficult to reduce the fL rate. Furthermore, there has been a desire to produce a sintered body with higher strength and less dimensional change due to sintering. Therefore, as a result of research, the present inventors added a) organic silicon polymer compound as a binder to silicon powder, molded it to obtain a molded body, and then heated the molded body at 1400 to 1500° in a nitrogen or ammonia gas atmosphere.
We have invented a method for producing a silicon nitride-based sintered body, which is characterized by heating and sintering with C. In the present invention, the organosilicon polymer compound that is the binder hardly disappears, and a part of it can be obtained by heat treatment (hereinafter referred to as sintered material 4.1). The silicon powder used in the present invention may be commercially available silicon powder with a particle size of 250 to 325 meshing force (C). ) one thing is used.

(a) n=1. Polysylmethylene siloxane n=2. Polysilethylene siloxane n=6. Polysilphenylenesiloxane (b) n=1. Polymethylenoxysiloquine n=2. Bo'J
Ethylene oxine quinane n-6, polyphenyleneoxysiloxane n-12, polydiphenyleneoxysiloxane (c) n=1. Polysylmethylene n=2. Polysilethylene n-3, polysiltrimethylene n-6, polysilphenylene n = 12, polysildiphenylene (d) (e) The skeleton components described in (a) to (d) above are chained,
Cyclic and knee: those containing as a partial structure of at least one of the dimensional structures, or a mixture of (a) to (d).

1, the compound 1' can be used as it is in powder or liquid form, or as necessary, in a solvent that dissolves the compound, such as benzene, toluene, y/1/no, \1san, ether, etc. Tetrahydrofuran, Georan-nano, Chloro 1
Luno 1, methylene chloride, petroleum ether, petroleum・\nnnnno,su//' L, lin, DMSOl DMF,
DVB and other organosilicon polymers 11Z8''1) Using a melt with πi kV, it can be made into a viscous liquid and used as a binder for silicon powder.The mixing ratio with respect to silicon powder is ljA l':6 Molecular compound Si/C
If the ratio and average molecular weight are silicon powder,
An organosilicon polymer compound mainly composed of 1 methylene lumethylene, an organosilicon polymer compound mainly composed of polysilapropylene, or an organosilicon polymer mainly composed of polyphenylborosiloxane, with an average molecular weight of 800 to 5000, adjusted by Compound 250-3
When mixed with 25 mesh silicon powder, it is preferable that the weight is 10 to 20 weight: ■≦. When mixing these, there is no need to heat them, and it only takes 1 minute to mix them at room temperature. Molding is done using mold compression molding or roll compression molding.
Compression molding at F 1-2 ton/crn'. The molded body thus printed is sintered by heating to 1400 to 1500°C in an atmosphere of nitrogen or ammonia scum.Heating is carried out from room temperature to about 10110°C in 3 to 6 hours. Then at around 1000℃ 30
After holding for ~120 minutes, io~1400~1 in ~60 minutes
It is effective to increase the temperature to 500° C. in order to obtain a sintered body with low porosity and high strength. Further, it is preferable to hold the final sintering temperature for 40 minutes because the conversion rate to silicon nitride is higher than that at the final sintering temperature. Sintering temperature: 140
If the temperature is lower than 0°C, the nitriding reaction will be uneven and it will be difficult to obtain a high strength product, and if the temperature exceeds 1500°C, the strength of the binder will deteriorate significantly. The present invention is industrially extremely useful since it is possible to obtain a sintered body with lower porosity, higher strength, and smaller dimensional change than conventional methods.

Example 1 Silicon powder (commercially available, particle size 250 mesh or less) was mixed with 20 parts by weight (2
0% by weight) at room temperature. Then molding pressure 1to
Compression molding was performed at a pressure of n/cm' to obtain a molded body of lO10x60x5. The bulk density of this molded body is 1.77 g/c
m! Met. This molded body was heated from room temperature to 1000℃ for 5
After heating at A for 60 minutes and holding at 1000℃ for 60 minutes, +40
The temperature was raised to 0'0 in 30 minutes and held at 1400°C for 60 minutes for sintering. The results of X-ray diffraction of the sintered body f, i
It was confirmed that it was composed of SiC with 13L (14H) and a fine diameter. Further, the properties of the sintered body are as shown in Table 1, and the sintered body had higher strength and excellent airtightness than those produced by the conventional nitriding reaction sintering method.

Table-1 The same silicon powder as used in Example 2.3, Comparative Example, 2.3.4, and Example 1 was mixed with the number, '
A molded body of 20 x 130 x 5 mm was obtained by combining the binder materials of the mold and compression molding at a molding pressure of 2 tons/crIf. This molded body is baked indoors in ammonia scum. Table 2 shows the properties of the obtained sintered body.

Claims (1)

[Claims] A silicon nitride characterized by adding an organosilicon polymer compound as a binder to silicon powder, molding it to obtain a molded body, and then heating and sintering the molded body at 1400 to 1500°C in a nitrogen or ammonia gas atmosphere. Method for manufacturing sintered body.