JPS60234937A - Titanium diboride-base sintered hard alloy - Google Patents

Abstract

PURPOSE:To obtain a TiB2-base sintered hard alloy having very high hardness and higher sinterability than a conventional alloy by bonding TiB2 with an Ni- Zr alloy so as to make use of the high hardness and wear resistance of TiB2. CONSTITUTION:TiB2 is bonded with an Ni-Zr alloy prepd. by adding 2-98.7wt% Zr to Ni to obtain a TiB2-base very hard alloy. The amount of the Ni-Zr alloy used is 0.1-50wt% of the amount of TiB2. When the TiB2-base very hard alloy contg. the Ni-Zr alloy as a binder is used, a high density sintered body is easily manufactured by conventional sintering under ordinary pressure. The TiB2-base sintered hard alloy is provided with advantages of TiB2 and has high hardness and deflective strength.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to titanium diboride (hereinafter abbreviated as TiB2).
This invention relates to a titanium boroside matrix superalloy in which particles are used as a matrix and the particles are bonded by a bonding metal.

[Prior art]

TiB2 is made from tungsten carbide (WC) or titanium carbide (Ti), which are conventionally known constituent materials of cemented carbide.
It has higher hardness, greater oxidation resistance, and excellent wear resistance than C), so if a high-performance cemented carbide using TlB2 as a substrate is made, it will have high hardness and wear resistance. It is expected that an excellent cemented carbide can be obtained.

However, when producing this type of cemented carbide, it is important to discover the optimal bonding metal, and in conventional WC-based cemented carbide, the optimal bonding metal is Co or Co-Mo alloy.
The TiC-based cemented carbide was a Ni-Mo alloy.

On the other hand, as for TiB2-based cemented carbide, there is still no satisfactory bonding metal. For example, Cr, Si, C
Pure metal-based bonding metals such as u, Co, Fe, and Ni and alloy-based bonding metals such as N1-P, Ni-B, and Co-B are being considered; The bonding metal has insufficient interfacial bonding with the TiB2 particles, has poor sinterability, and has low mechanical strength, so it is not practical.

〔the purpose〕

The present invention provides a bonding metal for TiB2 that has superior sinterability and mechanical properties than the conventional bonding metal for TiB2 described above.
The purpose of this invention is to provide a titanium diboride matrix cemented carbide having extremely excellent various properties.

[Summary of the invention]

The present invention is characterized in that an alloy of nickel (Ni) and zirconium (Zr) added thereto is bonded as a bonding metal.

Ni- which is a binding metal for TiB2 according to the present invention
The composition of the Zr alloy is (2 to 98.7)% by weight Zr relative to Ni as shown in the Ni-Zr alloy phase diagram shown in FIG.

Furthermore, the amount of bonded metal to TiB2 is (0.1 to 50%
)% by weight (Ni-Zr) alloy.

When the Ni-Zr alloy according to the present invention is used as a bonding metal, it can be easily formed into a high-density sintering method using a normal pressureless sintering method (sometimes referred to as a pressureless sintering method). Ti
A sintered body of B2 group cemented carbide is obtained.

The TiB2 matrix cemented carbide obtained by the present invention is a TiB2 matrix cemented carbide having high hardness and high flexural strength, which has the advantages of TiB2.

[Embodiments of the invention]

The present invention will be explained in detail below.

First Example (1) Method for producing TiB2 substrate cemented carbide 0.2% by weight of Ni-30% by weight Zr alloy powder was added to TiB2 powder of 325 mesh or less to form a WC-Co cemented carbide. Additionally mixed and ground in a ball mill, and these mixed powders are
It was molded into a rectangular parallelepiped of 5 x 10 x 30 mm3 with a compression pressure of 4 ton/cm2, and heated at 2100°C on a graphite mold (or carbon) stand in a vacuum of ~10-3 mmHg.
Heat for an hour.

(2) Characteristics of the TiB2-based cemented carbide of the present invention obtained by the above manufacturing method (a) Composition A cemented carbide made of TiB2 alone with high composition.

(b) Porosity The porosity is 0.01% or less.

(c) Pickers hardness (load 100g) 3350-34
00 kg/mm2. (TiB2-(N
i-Zr) line) (d) bending strength (JISH5501
-1956 test method) showed 75 to 85 kg/mm.

(e) Structure state Figure 3 is a photo taken with a metallurgical microscope. The mesh-like part is Ti.
It can be seen that this is a B2 grain boundary and that there are no pores at all.

In this way, it can be seen that a sintered body in which 3% or less of Ni-Zr alloy is added to TiB2 can be obtained as a high-density TiB2 cemented carbide with no pores. (3) Comparison with conventional cemented carbide WC-Co alloy, WC-TiC-Co alloy, Ti
C-(Ni-Mo) alloy and Cr3C2-40WC-
Pickers hardness of 15Ni alloy etc. is 1000-2500
kg/mm2 (see WC-Co line in FIG. 2), the TiB2 matrix cemented carbide of the present invention is significantly superior in hardness. Moreover, the porosity of the conventional TiB2 sintered body is 4 to 1.
0%, the TiB2 matrix cemented carbide of the present invention is significantly superior in that it achieves high density.

The bending strength of the conventional alloys mentioned above is 40 to 180 kg/mm2.
Since the flexural strength of the TiB2-based cemented carbide of the present invention is also within this range, the TiB2-based cemented carbide of the present invention can sufficiently withstand use as a wear-resistant tool.

Second Example (1) Manufacturing method of cemented carbide TiB2 powder of 325 mesh or less and Ni-Zr alloy powder were pulverized and mixed in a ball mill made of WC-Co cemented carbide for 30 minutes. It was molded into a rectangular parallelepiped of 5 x 10 x 30 mm2 with a compression pressure of 4 ton/cm2, and graphite (
or carbon) on a stand made of vacuum to 10-3 mmH.
Heat at 1150-2100° C. for 1 hour in a vacuum of 100 g.

(2) Composition and addition amount N of the bonding alloy (Ni-Zr) used
The composition of Zr with respect to i is 10% by weight, 22% by weight, 30% by weight.
Nine types were used: % by weight, 37% by weight, 57% by weight, 61% by weight, 70% by weight, 76% by weight, and 90% by weight. or,
The amount of Ni-Zr alloy added to TiB2 is 3% by weight ~
It is 50% by weight.

(3) Properties of the TiB2-based cemented carbide of the present invention obtained by the above manufacturing method (a) Composition TiB2 (3 to 50) wt% (Ni-10 wt% to 90 wt%
wt% Zr).

(b) Vickers hardness (load: 100 g) As the amount of Ni-Zr alloy added increases, the hardness decreases, but T
iB2-(5-25) weight% (Ni-30 type weight% Zr)
As shown at each measurement point, 3200 to 1500 kg/m
m2 was shown.

(c) Flexural strength (based on the test method of JIS H5501-1956) The flexural strength did not change much even when the composition and addition amount of the Ni-Zr alloy changed, and was 60 to 82 kg/mm2. .

(d) Structure state FIG. 4 is an example of a photograph showing the metallurgical microscopic structure of the TiB2 matrix cemented carbide of this example, where the white part is the TiB2 phase and the black-gray part is the Ni-Zr alloy phase. Like this T
It can be seen that the iB2 particles are bonded by the Ni-Zr alloy and have almost no pores.

(4) Comparison with conventional cemented carbide Similar to the first example, the TiB2 matrix cemented carbide of the present invention is significantly superior in terms of sinterability and hardness.

In addition, even if sintered using a pressure sintering method such as a hot press method in addition to the pressureless sintering method, a cemented carbide with excellent hardness and no pores can be obtained as in the above two examples. can get.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain a TiB2 matrix cemented carbide that has better sinterability than conventional products, and to produce a very hard cemented carbide that takes advantage of the high hardness and wear resistance of TiB2. Furthermore, a cemented carbide with extremely excellent mechanical properties comparable to those of conventional products can be obtained.

In particular, it has traditionally been difficult to obtain a high-density sintered body of TiB2 alone, but by adding a small amount of the Ni-Zr alloy of the present invention, a TiB2 single sintered body with no pores can be obtained.

In addition, the cemented carbide of the present invention can be used in all types of wear-resistant tools like conventional WC-Co cemented carbide, and has a wider range of applications than conventional products due to its high hardness and wear resistance. Therefore, the industrial effect is extremely large.

[Brief explanation of the drawing]

Figure 1 is a phase diagram of the Ni-Zr alloy, Figure 2 is a comparative characteristic diagram of Vickers hardness between the TiB2 matrix cemented carbide of the present invention and conventional WC-Co, and Figure 3 is the TiB2 of the first embodiment. FIG. 4 is a metal micrograph of the substrate cemented carbide (500x magnification), and FIG. 4 is a metal micrograph of the TiB2 substrate cemented carbide of the second embodiment of the present invention. Patent applicant Katsuhiro Nishiyama's engraving of the drawing (no changes to the content) Figure 2 t 6 Figure ゛・East y 'L1- Drawing procedure correction BeK (41159tf [June 6 [1, Samurai 1, 1] Government official Re = Kazutomo Sugi, 1st person f'l- & 11f (Ol) 59th year q, 'j♂ [Seki No. 89368
Bow 2 Name of the invention 2 Hard alloy with titanium hydride substrate 1 3111 Whitening name 13 relationships h ′F\i, -t +,, l l Kumite f
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Claims (1)

[Claims] A titanium diboride matrix cemented carbide consisting of titanium diboride bonded by a nickel-zirconium alloy.