JPS6283377A - Manufacture of composite 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 "Field of Industrial Application" The present invention is suitably used in a method for manufacturing a composite sintered body for a cutting tool, and can also be used in a method for manufacturing high-temperature structural materials, engine parts, and the like.

"Prior Art" 5bN4 sintered bodies have high toughness and excellent thermal shock resistance, so they are beginning to be used as structural materials and cutting tools in place of heat-resistant alloys. Since 81sN< is a difficult-to-sinter material with high covalent bonding properties, attempts have been made to make it densified by various sintering methods. Reaction sintering, ordinary sintering, and hot pressing are known as typical sintering methods, but the reaction sintering method has a relative density of 86%, which makes it impossible to obtain high strength, and Both had the disadvantage that their properties deteriorated at high temperatures. Therefore, in order to further densify the reaction sintered body, a sintering aid is added to the metal Sl, and hot pressing is performed after reaction sintering.
1628 Publication), Method of dispersing whisker crystals called SiC whiskers in 5isN4 to improve high-temperature characteristics of 5isNn sintered body (Ceramics Association Journal 91 (11:)
1988, 491), Method for dispersing 5isN4 whiskers in 5isNa (Japanese Patent Application Laid-Open No. 56-92180
Publication No. 2), etc. were proposed.

"Problems to be Solved by the Invention" However, the method described in Japanese Patent Publication No. 59-501628 causes deterioration of high-temperature properties due to the addition of a sintering aid, and the method of dispersing whiskers makes sintering difficult. The properties at room temperature were also not very good. Therefore, conventional S
i When using sNA type tools, the lifespan of AlzOs
-There was a problem that it was shorter than Tic type tools.

It is an object of the present invention to solve the above-mentioned problems and provide a method for producing a composite sintered body that has superior high-temperature strength and high-temperature hardness compared to conventional 5isN4-based tools and Altos-Tic-based tools.

"Means for solving the problem" The means consists of 60 to 90% by weight of Si powder and 4% of the sintering aid.
20 to 90 volumes of powder consisting of 0 to 10% by weight, 40 to 5 volumes of whiskers, and 40 to 5 volumes of hard material are mixed, molded, and sintered after nitriding.

Here, the term "whisker" refers to a whisker crystal having a diameter of 0.1 to 0.15 μm, and the material thereof is preferably ceramic such as 5iCs 5isNa. A hard substance refers to a substance whose hardness at high temperatures is equal to or higher than that of 5lsNa.

"Function" The sintering aid promotes the sintering and densification of 5LlN4 produced by nitriding, but its content is less than 10% by weight of the raw material excluding whiskers and hard substances. If it exceeds 40% by weight, the high-temperature properties deteriorate, so the content was limited to 40 to 10% by weight. The types of sintering aids are AbOs r AIN * YxOs +
MgO + Zr (preferably one or more of oxides of h and rare earth elements, Alums / Yz0g molar ratio V
AhOs 5Y203 mixtures from a to Vx are preferred.

Sl powder changes to Si sNa by nitriding, but at this time, the relative density of the compact reaches about 75%, so the relative density of the mixture of SimNn and whiskers is 5%.
Unlike the case where the thickness reaches only about 5cm, almost no shrinkage deformation occurs during sintering, and the 95lsNa sinters in close contact with each other, making it easier to sinter. Nitriding is 1100-14
Even if the middle layer of a nitrogen stream at 00℃ or a mixture of nitrogen, hydrogen, and inert gas softens at high temperatures, it prevents the deterioration of the high-temperature properties of the sintered body by binding the 5isN4 particles together, and also prevents the entanglement of whiskers. This creates a large number of open pores in the molded body, facilitates nitrogen diffusion during nitriding, and promotes nitriding. Since these open pores become smaller due to the volumetric expansion when Sl is nitrided to SimNn and the vapor phase diffusion of 5isN4, they do not adversely affect the strength of the sintered body. When the amount of whiskers added in the molded article is less than 5 volume ciI, the above effect is poor, and when it exceeds 40 volume ciI, both molding and densification become difficult, so the amount added was limited to 40 to 6 volume ciI.

The hard substance improves the hardness of the sintered body at high temperatures, and is, for example, a carbide, nitride, or carbonitride of an IVa group element, Va group element, or VIa group element, or two or more selected from these. are mentioned, especially Tie,
One or more selected from TIN and T i CN are desirable. If the content of the hard substance in the sintered body is less than 6 volume units, its effect will be poor, and if it exceeds 40 volume units, sintering will be difficult, so the content was limited to the above range.

Sintering is performed in nitrogen at 1 to 200 atmospheres with a humidity of 1650 to 2000.
℃ gas pressure sintering or hot pressing at a temperature of 1600-1900°C in a carbon mold at 100-800 atm.

"Example" Passed through 360 mesh, purity 99%, 81% dry average particle size 0.
6 µm, purity 99.9% (! - AbOs, average particle size 1 µm, purity 99 µm Y2O3, average particle size 1 µm 1 purity 99 µm TiC, average particle size 1.5 µm 1 purity 99 µm T
iN, SLC whiskers and 5L3N4 whiskers were weighed and mixed in the proportions shown in Table 1, pressed into a mold at 1 ton/aA, and nitrided at 1800°C in a nitrogen stream.
A sintered body A1-I15 was produced by hot pressing at 800° C. and 201 t/ad.

Sintered compact 1, 1B, 44.47. M8. Mu11.41B
The cup 14 was obtained by the manufacturing method of the present invention, and the others are products outside the range.

The transverse rupture strength and
Table 1 shows the results of evaluating hardness and abrasion resistance.

Transverse rupture strength measurement method Transverse rupture strength is 1200℃ according to JIS standard R1601
The 8-point bending strength was measured.

The hardness is determined by grinding the sintered body into a 5NGN4B2 shape and J
A Rockwell superficial hardness of 45N was measured according to IS standard Z 2245.

Wear resistance was evaluated by grinding the sintered body into a 5NGN482 shape, cutting it under the conditions shown in Table 2, and measuring flank wear VB.

Table 2 As can be seen from Table 1, the products obtained according to the production method of the present invention had high high temperature strength and high temperature hardness, and were excellent in cutting performance.

"Effects of the Invention" As described above, according to the manufacturing method of the present invention, a composite sintered body suitable for cutting tools, high-temperature structural materials, engine parts, etc. can be obtained.

Patent applicant: Nippon Tokushu Tokugyo Co., Ltd. Representative Suzuki Tei -

Claims (2)

[Claims] (1) Si powder 60-90% by weight and sintering aid 40-1
A composite sintered body characterized in that 20-90% by volume of powder consisting of 0% by weight, 40-5% by volume of whiskers, and 40-5% by volume of hard material are mixed, molded, and sintered after nitriding. Manufacturing method. (2) The hard substance is a group IVa element, a group Va element, or a group VIa
2. The method for producing a composite sintered body according to claim 1, wherein the composite sintered body is a carbide, nitride, or carbonitride of a group element, or two or more selected from these.