JPH08225879A - Titanium nitrode sintered compact using aluminum as auxiliary and its production - Google Patents

Abstract

PURPOSE: To attain the sintering of TiN at a low temp. by adding Al and to ensure high performance of the resultant sintered compact because the added Al is converted into TiAl3 and AlN excellent in heat resistance and mechanical characteristics by a reaction with the TiN. CONSTITUTION: Aluminum is added to TiN powder by 3-20wt.% and they are hot-pressed in vacuum or in a nonoxidizing atmosphere of Ar, N2 , etc., under the conditions of >=1,300 deg.C temp. and >=150kg/cm<2> pressure to obtain the objective sintered compact having high strength, high hardness, a high m.p. and high electric conductivity.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention has high hardness, high strength and
The present invention relates to a high melting point, high electrical conductivity TiN sintered body and a method for producing the same.

[0002]

2. Description of the Related Art TiN is a ceramic having characteristics such as high hardness, high heat resistance expected from a high melting point, and high electric conductivity. Further, since TiN has a beautiful golden color, it has been conventionally used as a decorative alloy in addition to tool materials for high-grade wristwatches and the like. However, since TiN is difficult to sinter, these are mainly by surface coating using a sputtering technique.

By solving the difficulty of sintering of TiN so that a dense sintered body can be obtained, it can be used in many industrial fields. Up to now, a method of adding a metal such as nickel or cobalt in order to improve the sinterability of TiN (Yasuyasu Mitani, Hiroshi Nagai, Mikio Fukuhara, The Japan Institute of Metals, 42 , 5).
82-88 (1978), and A. Tsuge, H .;
Inoue and K.K. Komeya, Yogyo-
Kyokai-Shi, 82 , 587-96 (197).
4). ), The method of adding various ceramics (Moriyama Minoru,
Hiroo Aoki, Yoshikazu Kobayashi, Kiichiro Kamada, Journal of the Ceramic Society of Japan, 101 , 279-84 (1993). )
Has been studied, but has not yet achieved sufficient results.

[0004]

TiN is a ceramic which is difficult to sinter, and it is required to improve the sinterability by adding some sintering aid. At that time, it is required that the characteristics of TiN, such as high hardness, high electrical conductivity, and heat resistance expected from a high melting point, are not impaired. The present invention has been obtained as a result of multi-faceted search for a sintering aid of TiN from the above viewpoint, and improves the sinterability by adding Al. By utilizing the chemical reaction that occurs between Ti and TiN, Al has excellent heat resistance and mechanical properties.
Excellent Ti by converting to iAl ₃ and AlN
An N sintered body and a method for manufacturing the same are provided.

[0005]

To achieve the above object, a TiN sintered body according to the present invention is a dense, high hardness, high hardness composed of TiN and TiAl ₃ and AlN produced by a chemical reaction during sintering. It is a high-strength sintered body, and its manufacturing method is to prepare a mixed powder in which 3 to 20% by weight of Al powder is added to TiN powder, and preform this, or directly form graphite, boron nitride or the like. After filling the mold,
The structural feature is that hot pressing is performed under the conditions of a temperature of 1300 ° C. or more and a pressure of 150 kg / cm ² or more in a vacuum or a non-oxidizing atmosphere such as argon or nitrogen.

[0006]

The TiN raw material powder having a fine grain size is applied. If the average grain size exceeds 50 μm, the structure of the sintered body becomes inhomogeneous and sufficient strength characteristics cannot be obtained. The average particle size is preferably 10 μm or less. A
l can be applied with a particle size of mesh grade, but in order to function appropriately as a sintering aid, T
It needs to be sufficiently dispersed at the stage of mixing with iN. Therefore, the particle size is preferably smaller than that of TiN. The amount of addition is 3 for TiN powder.
If the amount is less than wt%, the auxiliary effect cannot be obtained sufficiently, and 2
Addition of more than 0 wt% leaves a large amount of unreacted Al. Therefore, the amount of Al added is adjusted in the range of 3 to 20% by weight according to the particle size of the TiN powder used.

These TiN powder and Al powder are sufficiently dispersed and mixed by a wet ball mill method using an organic solvent to obtain a raw material powder. This is hot-pressed under vacuum or in a non-oxidizing atmosphere such as argon or nitrogen under the conditions of a temperature of 1300 ° C. or higher and a pressure of 150 kg / cm ² or higher. Temperature less than 1300 ° C, pressure 150k
If it is less than g / cm ² , sufficient densification cannot be achieved. The TiN sintered body of the present invention is manufactured by the above method.

[0008]

[Examples and Comparative Examples]

Example 1 A mixed powder obtained by adding 20 wt% of Al powder having a particle size of 325 mesh or less to TiN powder having a particle size of 75 μm or less, ball-mixing in ethanol for 24 hours, and then drying in vacuum at 150 ° C. The body was hot pressed in nitrogen at 1400 ° C. for 1 hour at a pressing pressure of 360 kg / cm ² . Example 2 The same raw material as in Example 1 was used, the Al content was adjusted to 10% by weight, and hot pressing was performed under the same conditions as in Example 1. Example 3 5% by weight of Al powder having a particle size of 325 mesh or less was added to TiN powder having an average particle size of 1.3 μm, and the mixture was ball-milled in ethanol for 24 hours, and then dried at 150 ° C. in vacuum to obtain the powder. The mixed powder is vacuumed (1 × 10 ⁻³ Torr or less) at 1400 ° C. for 1 hour, and the pressing pressure is 360 kg / cm ^2.
Hot-pressed at. Example 4 The same raw material as in Example 3 was used, in vacuum (1 × 10 ⁻³ Torr or less) at 1300 ° C. for 1 hour, and the pressing pressure was 360 kg / cm ^2.
Hot-pressed at. Example 5 The same raw material as in Example 3 was used, the Al content was adjusted to 10% by weight, and hot pressing was performed under the same conditions as in Example 3. Example 6 The same raw material as in Example 5 was used, in vacuum (1 × 10 ⁻³ Torr or less) at 1300 ° C. for 1 hour, and the pressing pressure was 360 kg / cm ^2.
Hot-pressed at.

Comparative Example 1 The same raw material as in Example 1 was hot pressed in nitrogen at 1200 ° C. for 1 hour at a pressing pressure of 360 kg / cm ² . Comparative Example 2 The same raw material as in Example 5 was used, in vacuum (1 × 10 ⁻³ Torr or less) at 1200 ° C. for 1 hour, and the pressing pressure was 360 kg / cm ^2.
Hot-pressed at. Comparative Example 3 TiN powder having an average particle size of 1.3 μm was placed in a vacuum (1 × 10
^-3 Torr or less) 1400 ° C for 1 hour, press pressure 360
It was hot pressed at kg / cm ² .

The bulk density and the apparent density of each of the sintered bodies obtained in the above Examples and Comparative Examples were measured by the Archimedes method.
The open porosity was determined, and the bending strength at room temperature, fracture toughness value (K _IC ) and Vickers hardness were determined. Flexural strength by three-point bending of a span 30mm test piece having a thickness of 3mm 4mm wide test, K _IC is notched depth 1mm width 0.1mm in thick test piece 4mm width 3mm, the lower span 3
By 4-point bending test with 0 mm upper span 10 mm (S
ENB method), and Vickers hardness was determined by measurement under a load of 100 g and a holding time of 15 seconds. The results are shown in Tables 1 and 2. However, in the comparative example, hardness could not be measured because of high porosity.

[Table 1] Characteristic values in each example

[Table 2] Characteristic values in each comparative example

As can be seen from the numerical values in these tables, Al
When added as a sintering aid and hot-pressed at 1300 ° C. or higher, compared with the case of TiN alone or hot-pressed at less than 1300 ° C., significant densification, strength, and K _IC Improvement was recognized. In addition, a sufficient hardness is obtained.

The powder X-ray diffraction patterns of Example 1 and Example 5 are shown in FIG. As is clear from the figure, the added Al is TiN
It can be seen that TiAl ₃ and AlN were produced by reacting with.
The melting point of Al is 660 ° C., and the melting points of TiAl ₃ and AlN are 1340 ° C. and 2450 ° C., respectively. Therefore,
At the time of sintering, the liquid phase composed of Al promotes the sintering, and Al changes into high melting point TiAl ₃ and AlN. Therefore, it is considered that the obtained sintered body can be expected to have heat resistance.

[0013]

According to the present invention, a TiN sintered body can be sintered at a lower temperature than before. Furthermore, the obtained sintered body has excellent mechanical properties, which makes it possible to apply it to cutting tool materials, decorative alloys, and the like.

[Brief description of drawings]

FIG. 1 is a powder X-ray diffraction diagram in the case of Example 1 (1) and Example 5 (2).

Claims (2)

[Claims] 1. A sintered body produced from a mixed powder in which 3 to 20% by weight of aluminum (Al) is added to titanium nitride (TiN). 2. A mixed powder obtained by adding 3 to 20% by weight of Al to TiN is hot-pressed in a non-oxidizing atmosphere at a temperature of 1300 ° C. or higher and a pressure of 150 kg / cm ² or higher. Manufacturing method of sintered body.