JPS6117470A - Manufacture of titanium carbide block - 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 [Industrial Application Field] This invention has a crystal grain size of 11+, which has high wear resistance and can therefore be used for applications such as cutting tools and press molds.
A method for producing a lump consisting of a single crystal or a polycrystalline body of titanium carbide of 1+++ or more (hereinafter referred to as TiC).

[Prior art and its problems]

Conventionally, the most common method for manufacturing single crystals with large grain size is the rotational pulling method, in which a molten material is slowly rotated and pulled up. It was not possible to create a single crystal of such a high melting point substance.

One way to make a single crystal of TiC is to use molten Fe group metal (
By adding Ti or a Ti compound and C to Ni or Fe) and utilizing the dissolution/precipitation mechanism in Fe group metals,
Although there is a menstrum method for producing coarse TiC single crystal powder, it is industrially difficult to produce large TIC single crystals with a crystal grain size of 1 mm or more using this method.

Generally, some methods for producing polycrystals by melt solidification are also used, but this method is limited to the production of inorganic oxide polycrystals.

[Purpose of the invention and findings]

As a result of repeated research to produce a Tie mass with a large crystal grain size, the present inventor has developed an extremely industrial method that is completely different from the conventional single crystal production method and polycrystal production method,
Furthermore, we have discovered a method for producing TiC aggregates with large crystal grain sizes.

That is, first, TiC powder is press-molded to form a green compact,
A laser beam is applied to this powder compact to rapidly melt the entire TiC powder compact, which is then solidified to produce a lump of TiC single crystal or polycrystalline material with large grain size in an extremely short time. I found out that it can be done.

[Components of the invention]

The present invention will be explained in detail below.

(1) Press molding process The average particle size of TiC powder used in press molding is 0.5
~5.0 μm is preferred. The average particle size of TiC powder is 0.
This is because if the thickness is less than 5 μm, the amount of impurities such as oxygen in TiC increases, and if it exceeds 5.0 μm, compressibility decreases and press formability deteriorates.

The press molding is preferably carried out at a molding pressure of 5 to 30 Kp/-.

The size of the powder compact largely determines the size of the lump after melting and solidification, but it is preferable that the diameter is 30 WA or less, since it will be irradiated with a laser beam in the next step.

(11) Melting/solidifying process The laser beam is generated, for example, by a CO2 gas laser device that generates infrared rays with a wavelength of 10.6 μm. The laser beam may be applied to one point on the powder compact. Melting begins at that one point, and melt is generated one after another due to volumetric contraction and convection of the melt. The output of the laser device must be as large as 5 KJ/n+sec or more, and by applying the laser beam at the above output preferably for 0.5 to 10 minutes, the powder compact is rapidly melted by C2.

In order to avoid undesirable reactions such as oxidation of TiC, it is desirable to perform the melting in an inert gas atmosphere such as Ar gas. The inert gas pressure at that time is preferably 1 atmosphere.

Then, solidification is performed by natural cooling after stopping the application of the laser beam (C2).

By the method of the present invention, a lump of TiC single crystal or TiC polycrystal having a grain size of 1 or more is produced.

〔Example〕

Hereinafter, the structure and effects of the present invention will be explained in detail by showing examples together with reference examples.

Example 1 10 Kg/mj of TiC powder with an average particle size of 1.5 μm
, to create a disc-shaped green compact with an outer diameter of 15 mm and a thickness of 8 mm, and this green compact was placed in an Ar atmosphere (A
A laser beam generated from a CO2 gas laser device with an output of 10 KJ/n5ec was irradiated for 1 minute in a vacuum chamber with a gas pressure of 1 atm. ). The entire compact was melted by this irradiation.

Thereafter, it was solidified by natural cooling to produce a 6.23f spherical (diameter: about 7mm) lump.

When the structure of this lump was observed using a microscope and subjected to X-ray diffraction, it was confirmed that this lump was a single crystal of TiC.

Example 2 TiC powder with an average particle size of 2.0 μm was wet-pulverized and 1.
After reducing the diameter to 0 μm, press molding was performed at a pressure of 15 kg/- to create a disk-shaped green compact with an outer diameter of 20 mm and a thickness of 20 mm. Atmospheric pressure), laser beam irradiation was performed for 1.5 minutes using the same CO2 gas laser device as in Example 1. The entire compact was melted by this irradiation.

After that, it is solidified by natural cooling and has a T of 27.692.
An iC mass was produced.

This TiC lump is spherical with a diameter of about 10 m, and T
It was a polycrystal with an iC crystal grain size of 2.0 Te.

Reference Example 1 From the lump made of TiC single crystal obtained in Example 1,
Cut out a rectangular parallelepiped with a size of 5 rrrm x 5 m x 3 in, and braze it to a cutting tool holder so that the cutting edge shape is 00.6° and σ, 6° in JIS.
.

A byte according to the present invention with lf, 1f, and 0.4 was created.

Using this byte, under the following conditions,
A micro-cutting test and a general cutting test were conducted.

Micro-cutting test conditions〉 Work material: 550C (Brinell hardness: 210) Cutting speed:
50m/min feed: 0.01te/rev.

Depth of cut: 0.2 mm Cutting time: 30 hours General cutting test conditions> Work material: SNCM439 (Brinell hardness: Cutting speed: 1
80m/min feed = 0.2 m/rev.

Depth of cut: 1.5, cutting time = 60 minutes For comparison of micro-cutting tests, commercially available W
C-S%Co ultrafine cemented carbide and WC-6%CO 1
0 cemented carbide on the cutting edge and the cutting edge shape is the same as the cutting edge of the present invention (hereinafter referred to as conventional alloy cutting tools 1 and 2, respectively), and using these tools, micro-cutting was carried out under the above conditions. I conducted a test.

In addition, for comparison of general cutting tests, commercially available Ti
c -20%TiN -10%MO□C-10%Ni cermet and WC-18%TiC-5%TaC-796
Cutting tools having a cutting edge made of CO's PIO cemented carbide and having the same cutting edge shape as the cutting edge of the present invention (hereinafter referred to as conventional alloy cutting tools 3 and 4, respectively) were prepared 1, and these tools were used to meet the above conditions. A general cutting test was conducted.

In each test, the flank wear width and crater wear depth of the cutting edge were measured, and the results are shown in Table 1.

As shown in Table 1, the TiC single crystal cutting tool of the present invention has extremely superior wear resistance compared to conventional alloy cutting tools 1 to 4.

Reference Example 2 A forming mold for a bearing adhesive retainer having a diameter of 5 m was prepared from the polycrystalline mass of TIC obtained in Example 2 by grinding it with a diamond grindstone.

Using this mold, a thin plate of 5US304 (thickness: 0.15 mm), previously punched into a predetermined shape, is pressed to create a retainer, and when the dimensions of the retainer deviate from the predetermined dimensions, The number of pieces processed until the end of the life span was determined.

With conventional die steel molds, only 200,000 pieces could be machined, and with K2O cemented carbide, only 1 million pieces could be machined, but with the mold made from the TiC lumps of the present invention. By using it, we were able to process 7 million pieces.

[Overall effect of the invention]

As described above, the present invention is industrially useful because it can produce a lump of TiC polycrystal in an extremely short time on the order of minutes, and can also produce a TiC single crystal in some cases. This is a great method. And the obtained T
Since the iC lump consists of TiC alone, TiC
It is an extremely useful material because it can take full advantage of its high hardness and wear resistance.

Claims (1)

[Claims] A titanium carbide aggregate characterized by press-molding titanium carbide powder into a compact, applying a laser beam to the compact to rapidly melt the entire titanium carbide compact, and then solidifying it. manufacturing method.