JPH1110409A - Ceramics cutting tool and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an Al2 O3 -SiC whiskers cutting tool at low price by restraining the raw material cost as low as possible so that the use of SiC whiskers is restricted to the cutting edge part of the cutting tool, and also to provide sufficient cost/performance enough to the cutting of ferrous cutting material such as gray cast iron and ductile cast iron. SOLUTION: In an Al2 O3 -SiC whiskers cutting tool, each of the cutting edge parts of a thickness of 2 mm or more and 4 mm or less is made up of an Al2 O3 - SiO whisker material (Iw), and the other part is made up of an Al2 O3 particulate material (Ip). It is preferable that the mean diameter of a SiC whiskers is 0.3 microns or more and 1 micron or less and the mean length thereof is 2 microns or more and 50 microns or less, and further the volume percentage of the SiC whiskers to the cutting edge part is 7% or more and 40% or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic cutting tool and a method for manufacturing the same, and more particularly, to a silicon carbide whisker-reinforced alumina-based cutting tool which is excellent in wear resistance and chipping resistance by high-speed cutting and has a reduced cost, and its manufacture. About the method.

[0002]

_2. Description of the Related Art Al ₂ O ₃ , Al ₂ O ₃ —TiC, S
A ceramic cutting tool made of i ₃ N ₄ or the like has an important position as a cutting tool used particularly at high speed because of its excellent oxidation resistance, high heat resistance, and high hardness at high temperatures. However, these ceramic cutting tools have the above-mentioned advantages, but also have Al ₂ O ₃ and A
l ₂ O ₃ —TiC ceramics have poor fracture resistance and
Since i ₃ N ₄ has a high reactivity with iron and has a drawback of poor abrasion resistance, its use area can be said to be extremely limited.

In order to improve the abrasion resistance of Al ₂ O ₃ ceramics, it has been attempted to increase the toughness and strength of composites such as ZrO ₂ , SiC whiskers, and the simultaneous composite of SiC whiskers and ZrO _2. Has been put to practical use. For example, high toughness in USP4218253, high strength have been Al ₂ O ₃ -ZrO ₂ ceramic is proposed, also JP 61-174165, Al ₂ O ₃ -SiC whisker cutting tool in USP4961757, JP-2- 1
Al ₂ O ₃ in thirty-nine thousand one hundred and two -SiC whiskers -ZrO
_Two cutting tools have been proposed, and in the case of composite ceramics obtained by compounding SiC whiskers, they show excellent performance especially for difficult-to-cut materials such as superalloys and high-speed cutting of gray cast iron. But S
iC whisker Al ₂ O ₃ based ceramic cutting tool that combines, since SiC whisker material is expensive, high price compared with other ceramics cutting tools, well widely used in the market with the exception of the cutting Ni-base superalloys The situation is not yet reached.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to pay attention to the amount of expensive SiC whiskers and to provide sufficient cost / performance for cutting iron-based work materials such as gray cast iron and ductile cast iron. An object of the present invention is to provide a SiC whisker reinforced Al ₂ O ₃ ceramic cutting tool and a method for producing the same.

[0005]

SUMMARY OF THE INVENTION The present invention provides an Al ₂ O ₃ −
In SiC whisker-based cutting tool, was made to limit the use of SiC whiskers in the portion of the cutting edge of the cutting tool is suppressed as much as possible raw material costs, to provide an inexpensive Al ₂ O ₃ -SiC whiskers based cutting tools for the purpose Things.

In the Al ₂ O ₃ -SiC whisker cutting tool according to the present invention, the cutting edge having a thickness of 2 mm or more and 4 mm or less is made of an Al ₂ O ₃ -SiC whisker material, and the other portions are made of Al ₂ O _3. It is characterized by being composed of a system particle material. Further, the manufacturing method is such that a mixed powder of an Al ₂ O ₃ —SiC whisker-based material and a mixed powder of an Al ₂ O ₃ —SiC particle-based material are laminated in a graphite die, and 1400 ° C. to 1850 ° C.
150 kg / cm for 10 minutes or more and 5 hours or less at ℃ or less
It can be due to ^more than 500 kg / cm ² or less of a method for pressure sintering under pressure.

Specifically, the configuration of the present invention is as follows. In the case of a negative type in which the rake face (upper and lower faces) and the side face are perpendicular to each other as shown in FIG. 1, the area from 2 mm to 4 mm (Iw) from the upper and lower faces of the tip is made of Al ₂ O ₃ —SiC whisker-based material. The central portion (Ip) is made of an Al ₂ O ₃ particle material.

A rake face (upper face) as shown in FIG.
In the positive type where the angle between the edge and the side surface is an acute angle, 2 mm or more and 4 mm or less on the cutting edge (Iw) side
It is composed of a ₂ O ₃ —SiC whisker-based material, and the other Ip is composed of an Al ₂ O ₃ particle-based material. Therefore, in the negative type, the thickness is 6.35 mm in composition.
It can be applied to chips (symbol 06) or more. On the other hand, in the positive type, the thickness is 4.76 mm (0 in the symbol).
4) Applicable to the above chips.

In any type of cutting tool, if the thickness of the Al ₂ O ₃ —SiC whisker-based material at the cutting edge portion is less than 2 mm, sufficient edge strength cannot be maintained, and the thickness exceeds 4 mm. However, it is not preferable from the viewpoint of suppressing the raw material cost. Al ₂ O applied to the cutting edge
_{In the 3-} SiC whisker-based material, the SiC whisker has an average diameter of 0.3 μm or more and 1 μm or less, and an average length of 2 μm or less.
It is preferable that it is not less than μm and not more than 50 μm. Also, S
It is preferable that the iC whisker is made of 7% by volume or more and 40% by volume or less with respect to the cutting edge portion, and the remaining is made of Al ₂ O ₃ . S
If the average diameter of the iC whiskers is less than 0.3 μm, the toughness and strength are not sufficiently improved, and if the average diameter is more than 1 μm, the abrasion resistance becomes insufficient and both are not preferred. On the other hand, if the average length is less than 2 μm, the strength is not sufficiently improved from the viewpoint of whisker reinforcement. If the average length is more than 50 μm, the probability of inducing a defect from the viewpoint of strength improvement is high, and neither is preferable. If the composite amount of the SiC whisker is less than 7% by volume, the improvement in toughness and strength is not sufficient, and if it is more than 40% by volume, the amount of Al ₂ O ₃ is relatively insufficient and the wear resistance becomes insufficient, resulting in a shortage. Is also not preferred.

As a result of examining various kinds of materials to be applied to portions other than the cutting edge portion, an Al ₂ O ₃ material should be applied in consideration of the consistency with the cutting edge portion so that the bulk strength does not decrease. And The applied Al ₂ O ₃ material may be Al ₂ O ₃ or Al ₂ O ₃ —ZrO ₂ , but from the viewpoint of having the same thermal expansion coefficient as the cutting edge portion,
Al ₂ O using SiC particles instead of iC whiskers
_{A 3-} SiC particle-based material is preferred. S used for this
The iC particles preferably have an average particle size of 0.2 μm or more and 2 μm or less. Also, the SiC particles are preferably 7% by volume.
At least 40% by volume, with the balance being Al ₂ O ₃ . When the average particle size of the SiC particles is less than 0.3 μm, the dispersion is insufficient in the mixing process, and when the average particle size is 2 μm or more, the strength of the material is reduced, and the strength of the particle-based material itself and the joining strength of the cutting edge are reduced. Neither is preferred. The volume percentage of the SiC particles is set to match the coefficient of thermal expansion of the Al ₂ O ₃ —SiC whisker-based material.

The Al ₂ O ₃ constituting the matrix in both the cutting edge portion and the portion other than the cutting edge can be reinforced by ZrO ₂ or TiC. At that time, the volume ratio of the strengthening phase to be added is 15% or less. If the volume ratio exceeds 15%, the amount of Al ₂ O ₃ is relatively small and the wear resistance is lowered, which is not preferable.

As a method of manufacturing the cutting tool of the present invention, a mixed powder of an Al ₂ O ₃ -SiC whisker-based material and a mixed powder of an Al ₂ O ₃ -based material are stacked and filled in a graphite die and hot-pressed. Is preferred. Al ₂ O
Mixed powder of a _3- SiC whisker-based material and Al ₂ O ₃
The mixed powder of the system material may be preformed in advance, and they may be set in a graphite die and hot pressed. If the sintering temperature in the hot pressing is less than 1400 ° C., the densification is insufficient, and if it is higher than 1850 ° C., Al ₂ O ₃ grains grow and the wear resistance is undesirably reduced. Also,
If the sintering is performed for more than 5 hours, the grain growth of Al ₂ O ₃ will again occur, and the abrasion resistance will decrease, which is not preferable. If the sintering is less than 10 minutes, the densification is insufficient, which is also not preferable. If the pressure is less than 150 kg / cm ² , the densification is insufficient, which is not preferable. If the pressure is higher than 500 kg / cm ² , there is no difference in the effect and there is no industrial significance.

In the present invention, in order to promote sintering of a ceramic cutting tool, a known sintering aid is added as a sintering aid for Al ₂ O ₃ ceramics such as MgO, Y ₂ O ₃ , NiO. Needless to say, this is acceptable.

[0014]

As described above, the Al ₂ O ₃ —SiC of the present invention is used.
The whisker-based cutting tool limited the use of expensive SiC whiskers to the cutting edge portion of the cutting tool, and constituted a portion other than the cutting edge portion from an Al ₂ O ₃ particle material. As can be seen from the examples described later, since parts other than the cutting edge also affect the cutting performance, in order to ensure that the cutting performance is comparable to that of a cutting tool reinforced entirely with SiC whiskers, the cutting edge is required. It is important to select the material for the other parts.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the following examples. Embodiment 1 FIG. 75% by volume of α-Al ₂ O ₃ having an average particle diameter of 1 μm or less, an average diameter of 0.6 μm, and an average length of 20 μm
A mixed powder (Iw) containing 25% by volume of SiC whiskers and a mixed powder (Ip) containing α-SiC particles having an average particle size of 0.5 μm instead of the SiC whiskers were respectively ball milled. After being sufficiently uniformly dispersed by wet mixing, it was dried. These mixed powders are filled in a graphite die in a layered manner as mixed powder (Iw) / mixed powder (Ip) / mixed powder (Iw), at 1800 ° C. and 450 k
Pressure sintering was performed for 1 hour in an Ar gas flow at g / cm ² . From the obtained sintered body, a cutting chip of model number SNGN120708 was cut out and ground. The thickness of the cutting edge portion of the Al ₂ O ₃ -SiC whisker material was 3.2 mm. This cutting tip was designated as A, and all of the mixed powder (I
The cutting insert made in the same manner as the insert A in w) was designated as B, and a cutting test was performed under the following conditions.

Cutting conditions 1 Work material Inconel 718 (aging after solution treatment) Cutting speed 100 m / min Feed 0.15 mm / rev Cutting depth 2 mm Holder FN11R-44A Cutting agent Not used

As a result, the cutting tip A was cut for one minute.
Has a flank wear width (Va) of 0.16 mm and a boundary wear (V
n) is 0.32 mm, Va of the cutting tip B is 0.13 m
m and Vn were 0.34 mm, which were almost the same evaluation results.

Similarly, a cutting test was further performed under the following conditions. Cutting condition 2 Work material FCD60 Cutting speed 300m / min Feeding 0.1mm / tooth Cutting depth 1.5mm Cutter CSBRN2525 (tested with 150φ, single blade) No cutting agent used As a result, 250mm 3 pass cutting The flank wear width at the time of cutting was 0.27 mm for the cutting tip A and 0.30 mm for the cutting tip B, which were almost the same evaluation results.

Embodiment 2 Α- having an average particle size of 1 μm or less
63 volume% of Al ₂ O _3, 32 volume% of SiC whiskers having an average diameter of 0.6 μm and an average length of 20 μm, and 5 volume% of zirconia having an average particle diameter of 0.4 μm containing 3 mol% of yttria. Mixed powder (IIw)
And the average particle size is 0.5 instead of the SiC whisker.
The mixed powder (IIp) containing the α-SiC particles of μm was wet-mixed with a ball mill and dispersed sufficiently uniformly, and then dried. These mixed powders were filled into graphite dies in a layered manner as mixed powder (IIp) / mixed powder (IIw), and 1600 ° C., 450 kg / cm ² , and 1 kg in an Ar gas flow.
Pressure sintering was performed for hours. From the obtained sintered body, model number RCGX
As a result of performing a cutting test for a cutting time of 1 minute under a cutting condition 1 of the first embodiment under the cutting condition 1 of Embodiment 1, Va was 0.12 mm and Vn was 0.24 mm.
, Which was a good result.

Embodiment 3 The composition of the mixed powder (IIw) obtained in the second embodiment has a composition not containing zirconia, that is, 68% by volume of α-Al ₂ O ₃ having an average particle size of 1 μm or less, an average diameter of 0.6 μm, and an average length. 20 μm Si
A chip D was prepared in the same manner as in the second embodiment except that the mixed powder (IIIw) was blended so that the C whiskers were 32% by volume. As a result of performing a cutting test for a cutting time of 1 minute under the cutting condition 1 of Embodiment 1, Va was 0.12 m.
m and Vn were 0.32 mm, which was good.

Embodiment 4 FIG. With a ceramic cutting tool having the same composition as the cutting tip A obtained in Embodiment 1, 100 outer diameters of the brake disk were turned under the following conditions. For comparison, a test was performed under the same conditions using a commercially available Si ₃ N ₄ cutting tool (tip E).

Cutting conditions Work material FC25 Cutting speed 800 m / min Feed 0.5 mm / rev Cutting depth 2 mm Cutting agent used Cutter CSBRN252 As a result, the cutting tip A has a Va of 0.19 mm, Vn of 0.5 mm, and the cutting tip E has a , Va is 0.46 mm, V
When n was 0.42 mm, the life was about twice as long in terms of the flank wear width.

Embodiment 5 Α- having an average particle size of 1 μm or less
Al ₂ O ₃ and a mixed powder IVw prepared by mixing 90% by volume of α-Al ₂ O ₃ and 10% by volume of SiC whiskers having an average diameter of 0.6 μm and an average length of 20 μm were prepared. These are mixed in a graphite die and mixed powder IVw /
Al ₂ O ₃ / mixed powder IVw, packed in layers,
Pressure sintering was performed at 00 ° C., 300 kg / cm ² for 1 hour in an Ar gas flow. From the obtained sintered body, model number SNGN1204
08 cutting chips were cut out and ground. This tip was designated as F, and 100 outer diameters of the work material were turned under the same work material (brake disc) and cutting conditions as in the fourth embodiment. As a result, when Va was 0.15 mm and Vn was 0.56 mm, the possibility of good life was shown.

Comparative Example Si ₃ N ₄ particles were used in place of the mixed powder (Ip) of the cutting tip A of the first embodiment. In the cutting test under the cutting condition 1, after cutting for 20 seconds, the distance from the interface with the cutting edge increased greatly. It was damaged, resulting in a remarkably poor evaluation result.

[0025]

As described above, in the ceramic cutting tool obtained by the present invention, the use of SiC whiskers is limited to the cutting edge portion of the cutting tool, the raw material cost is suppressed as much as possible, and the inexpensive Al ₂ O _{Since 3-} SiC whisker-based cutting tools can be provided, sufficient cost / performance can be provided for cutting iron-based work materials such as gray cast iron and ductile cast iron, and there is a possibility of contributing widely to the metal cutting industry.

[Brief description of the drawings]

FIG. 1 is a perspective view of a negative type cutting tool.

FIG. 2 is a perspective view of a positive type cutting tool.

Claims (6)

[Claims] 1. An Al ₂ O ₃ —SiC whisker-based cutting tool, wherein a cutting edge portion having a thickness of 2 mm or more and 4 mm or less is formed by A
l ₂ O ₃ constituted by -SiC whisker materials, ceramics cutting tool, characterized in that the rest is constituted by Al ₂ O ₃ based particulate material. 2. The method according to claim 1, wherein the Al ₂ O ₃ -based particle material is Al ₂ O ₃
The ceramic cutting tool according to claim 1, wherein the ceramic cutting tool is made of -SiC. 3. The size of the SiC whiskers is 0.3 μm or more and 1 μm or less in average diameter and 2 μm or more and 50 μm or less in average length, and the volume ratio of the SiC whiskers to the cutting edge is 7% or more and 40% or less. The ceramic cutting tool according to claim 1 or 2, wherein: Wherein the particles of the Al ₂ O ₃ -SiC particles based material, or less average grain size 0.2μm or 2 [mu] m, and volume fraction of SiC particles in said Al ₂ O ₃ -SiC particles based material 3. The ceramic cutting tool according to claim 2, wherein the content is 7% or more and 40% or less. 5. The Al ₂ O ₃ -SiC whisker material and / or Al ₂ O ₃ -SiC particles based Al ₂ O ₃ is less by volume ratio 15% ZrO constituting the matrix material
The ceramic cutting tool according to claim 2, reinforced with ₂ and / or TiC. 6. A mixed powder of an Al ₂ O ₃ —SiC whisker-based material and a mixed powder of an Al ₂ O ₃ —SiC particle-based material are laminated in a graphite die, and at a temperature of 1400 ° C. to 1850 ° C. for 10 minutes to 5 minutes. 150 kg / cm ² or more for 50 hours or less
A method for producing a ceramic cutting tool, comprising performing pressure sintering under a pressure of 0 kg / cm ² or less.