JPS6011265A - Cutting tool ceramics - 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 ceramic materials, and in particular to ceramics for cutting tools.

Alumina cutting tools, which are well known as one of the ceramics for cutting tools, have excellent wear resistance but are prone to chipping. Improvement has been considered one of the major goals of development. One solution to these requirements is to add approximately 30% by weight TiC to A120a.
A1゜Oa' is a composite of A1゜Oa' that improves fracture resistance due to thermal shock by making the crystal grains finer and compensating for the inherent characteristic of alumina, which is that the thermal conductivity decreases as the temperature increases.
TIC ceramic tools were invented.

Al2O3TfC ceramic tools have higher toughness and better fracture resistance due to thermal shock than so-called white thread ceramic tools made of worn alumina, so they are suitable for turning of high-hardness materials that are difficult to use with white ceramic tools. It is particularly effective in applications such as milling of cast iron materials. However, even in this Al2O3TiC ceramic tool, under cutting conditions where the cutting edge temperature exceeds 1200°C, the high-temperature hardness of the TiC contained in a large amount is lower than that of Al2-03, resulting in poor wear resistance and high hardness. There was a drawback that boundary wear was likely to occur on the cut surface of the material.

An object of the present invention is to improve the above-mentioned drawbacks of the prior art and to provide ceramics for cutting tools that have extremely high thermal conductivity, high toughness, and excellent chipping resistance.

The present invention is characterized in that 5-20% by weight of TiB2 powder and 5-20% by weight of TiN powder are mixed with Al2O3 powder, and 1-10% by weight of ZrO2 is further added.

In the present invention, similar to TiC in Al2O3TiC ceramics, TiB2, TiN and Z
rO2 has a structure dispersed in Al2O3, and as is well known, it plays the role of inhibiting grain growth of alumina, increasing toughness, and suppressing the growth of minute racks.

However, when a large amount of Tf 82, which is a difficult-to-sinter material, is mixed into AI 20g TiN, there is a drawback that the firing temperature becomes high and the particle size increases to around 10 μm.

The addition of Zr 02 in the present invention compensates for this drawback, and Al2O37! This has the effect of improving the sinterability of B2. In addition, in the present invention, 0.05 to 2.5 weight%
By adding M(10) and AIN, sinterability can be further improved and grain size growth can be suppressed.

Ceramics according to the present invention can usually be obtained by hot pressing a mixed powder having the above composition range, but it can also be obtained by hot isostatic pressing after hot pressing, or after normal pressure firing. Similar results can be obtained by hot isostatic pressing. Further, in the present invention, Tl
The reason why the amount of B2 powder is limited to 5 to 20% by weight is that if it is less than 5%, there is no effect of adding it, and if it is more than 20%, the particle size will conversely grow large. Regarding ZrO2, if it is less than 1%, there is no effect when added, and if it exceeds 10%, the thermal shock resistance decreases, so the content was limited to 1 to 10%. Also, M
(The reason why the total amount of 10 and AIN powder was limited to 0.05 to 2.5% by weight is that below 0.05% by weight, Al2
This is because there is no grain refining effect of 011, and when the amount exceeds 2.5% by weight, a spinel layer is formed at the grain boundaries, resulting in embrittlement.

In addition, the amount of Y203 added was 1.0 molar ratio to ZrO2.
The reason for limiting it to 0 to 3.0 mol% is to make Zr 02's crystal type mainly tetragonal (phase) to improve fracture strength, and when it is less than 1.0%, it is mainly monoclinic (M phase). So, 3.
When it exceeds 0%, the cubic crystal (C phase) becomes the main component and both Y2
0 The effect of adding a is weak.

Example 1 15% by weight of Ti 82 powder with an average particle size of 1.2 μm.

10% by weight of TiN powder with an average particle size of 0.7 μm, 5% by weight of ZrO2 powder with an average particle size of 0.1 μm, and 0.5% by weight of ZrO2 powder with an average particle size of 0.1 μm.
The remainder is 1 μm Al2O3 powder, and further MaO0
, 5% by weight, and 1.0% by weight of AlN were mixed and ground in an alumina ball mill using ethyl alcohol for 48 hours, dried in vacuum, molded at 2t/cm2, and pressed at 1500°C in vacuum. 200kg/cII12
Pressure sintering was carried out by holding for 10 minutes while applying pressure to obtain a sintered body.

Cutting tool tip 5NGN453 was made from this sintered body, and Al2Q3-30%T, which has been widely used in the past, was made from this sintered body.
Using the iC chip as a comparison material, the workpiece material DAC (H86
A cutting test was conducted using 5).

Cutting speed is 50 m/min and 70 m/n+in
The depth of cut is 1.5a+n+ each, and the feed is 0.4ml/ll/
It was set as reV.

As shown in FIG. 1, the ceramics according to the present invention exhibited excellent cutting performance with significantly less boundary wear loss than the conventional Al2O37IC ceramics.

Example 2 10% by weight of TfB2 powder, 10% by weight of TiN powder, 5% by weight of ZrO2 powder, 0.1% of Y20a powder
2% by weight, the balance being Al2O3 powder, mixed and pulverized for 48 hours in an alumina ball mill using ethyl alcohol, dried in vacuum, and then 2 t/cm'
molded in vacuum at 1500℃ and pressure 200kg/'ca.
Pressure sintering was performed at n' to obtain a sintered body.

A test piece of 8×4×25+11111 was cut out from this sintered body and subjected to a bending test. Average bending strength is 140kg
/mm2, which proved to have extremely high strength compared to commercially available AI 203-30% TiC ceramics.

Next, a cutting tool tip 5NGN432 was prepared from this sintered body, and a milling test was conducted using a commercially available (7) AI 203 30% Tf C tip as a comparison material and a workpiece material SCM440. The incision was 2n+m.

As shown in FIG. 2, the ceramic according to the present invention exhibited a wider cutting area than the conventional Al2O3TiC ceramic.

As is clear from the above examples, the ceramics for cutting tools according to the present invention have fewer boundary wear gates and are highly tough, exhibiting excellent properties as so-called ceramics for thermal tools, and are extremely useful industrially.

[Brief explanation of the drawing]

Figure 1 shows ceramics according to the present invention and conventional AI
20. -Characteristic curves showing cutting test results for TiC ceramics; FIG. 2 also shows milling test results for ceramics according to the present invention and conventional Al2O3 - TiC ceramics. Feed 2 Figure feed

Claims (1)

[Claims] 1. 5-20% TiB by weight 2.5-20% TiN
. A ceramic for a cutting 611 tool, characterized in that it contains 1 to 10% Zr 02 , the remainder 'tJ<A1°03 and unavoidable impurities. 2. Claims 1, 8.
I N, MU 0 (7) On the other hand, also 'ri, both together.
Ceramics for cut 11 tools, characterized in that 0.05 to 2.5% by weight is added. 3.Claim 1, paragraph 8.
1.0-3.0% molar ratio of Y20a to rO2
Ceramics for cutting tools, characterized by containing. 4. What is described in claim 2 (1) Zr
Cut I! characterized by containing Y203 in a molar ratio of 1.0 to 3.0% with respect to O2! 111 Ceramics for tools.