JPH07136810A - Ceramic tool for cutting very hard material - Google Patents

Abstract

PURPOSE:To improve the abrasion resistance against a very hard material when the material is cut and worked at high speed, and to restrict peeling of a coating film by specifying the average particle size of the composition particle of a ceramic main body, and by specifying the thickness of the coating film. CONSTITUTION:A ceramic tool comprises a sintered body, for which a sintered material and a sintering assistant are mixed together and sintered, and at least one layer coating film to be formed on the surface of the sintered body. The average particle size of the overall composition forming the sintered body is no more than 1mum, and the sintered material comprises 90-50wt.% of powder of Al2O3 composition and 10-50wt.% of at least one type of powder of carbide, nitride or carbonitride of elements belonging to IVa, Va, and VIa groups, where the overall amount is considered to be 100wt.%. The amount of the sintering assistant is 0.2-5.0wt.% to 100wt.% of sintered material, while the coating film comprises carbide, nitride, carbonitride of elements belonging to IVa, Va, VIa groups. Al2O3 or AlON, and each layer is no more than 2mum in thickness, and the entire thickness is 0.2-20mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic tool which is excellent in abrasion resistance, mechanical strength and the like and can be used for high speed cutting of high hardness materials such as carburized and hardened steel, die steel and tool steel.

[0002]

2. Description of the Related Art High hardness materials such as carburized and hardened steel, die steel and tool steel have been conventionally ground by a grindstone.
In order to improve the processing efficiency and process at higher speed, alumina-
A shift to cutting with a ceramic tool such as titanium carbide or a CBN tool has been made. However, the alumina-titanium carbide based ceramic tool has a short life, is poor in reliability, and cannot cope with speeding up of cutting work, and recently, a CBN tool is often used. But CBN
Although the tool has excellent cutting performance, it is very expensive,
There is a great demand among users for the development of a ceramic tool that is inexpensive and has a high performance comparable to that of a CBN tool, especially in high-speed cutting.

Therefore, various attempts have been made to improve the wear resistance and fracture resistance of ceramic tools such as alumina-titanium carbide-based ceramic tools. In the technique disclosed in Japanese Patent Laid-Open No. 4-114955, By firing a raw material powder in which a fine powder of zirconium oxide or the like is mixed with a fine powder of alumina, the strength and toughness are improved, and in JP-A-4-289002 and 5-69205. , Alumina, titanium carbide, on the surface of the ceramic base material,
There is disclosed a technique of improving wear resistance by providing a coating film made of a carbide of an alloy of titanium and aluminum. Although these cutting tools are superior in performance such as abrasion resistance compared with conventional ceramic tools, especially in high-speed cutting, they do not reach CBN tools, and the development of ceramic tools that can be used for high-speed cutting Is desired.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above problems and provides a ceramic tool for cutting which can be used for cutting a high hardness material in a high speed cutting process comparable to the cutting conditions of a CBN tool. The task is to do.

[0005]

A ceramic tool for cutting a high hardness material according to the first aspect of the present invention is a sintered body obtained by mixing a sintering raw material and a sintering aid and firing the mixture, and the surface of the sintered body. In a ceramic tool for cutting, which comprises at least one coating film formed in step 1, the average particle diameter of all components constituting the sintered body is 1 μm or less, and the total amount of the sintering raw material is 10 μm.
90 wt% of Al ₂ O ₃ component powder, and 10 to 50 wt% of one or more powders of IVa, Va, and VIa group carbides, nitrides, and carbonitrides. And the sintering aid is 100% by weight of the sintering raw material.
0.2 to 5.0% by weight, and the coating film is made of IVa, Va, or VIa group carbides, nitrides,
It is made of carbonitride, Al ₂ O ₃ or AlON, and each layer has a thickness of 2 μm or less and a total thickness of 0.2 to 10 μm.
Is characterized in that.

A second aspect of the present invention is characterized in that the average particle size of all components constituting the sintered body is 0.7 μm or less, and the thickness of each layer of the coating film is 1 μm or less. Third
The invention is characterized in that the Al ₂ O ₃ component powder is composed of 95 to 50% by weight of Al ₂ O ₃ powder and 5 to 50% by weight of ZrO ₂ powder, when the total amount is 100% by weight. And Furthermore, in the fourth invention, the coating film is composed of a plurality of layers, and the innermost layer is made of Al ₂ O ₃ or AlON and has a thickness of 1 μm.
The following layers, the outermost layer of which is TiN and has a thickness of 0.5 μm
The ceramic tool of the fifth invention is characterized in that the average flank wear amount measured under the specific test condition described in claim 5 is 0.2 mm or less.

The above "sintering raw material" is the main component "Al ₂
O ₃ component powder ”and“ one or more powders of carbides, nitrides, and carbonitrides of IVa, Va, and VIa group elements ”(hereinafter, referred to as“ powder such as titanium carbide ”). “Powder such as titanium carbide” includes IVa such as titanium and zirconium.
Powders of carbides, nitrides, and carbonitrides of Group VI elements, such as Va group elements such as vanadium and tantalum, and VIa group elements such as chromium and tungsten can be used. Specifically, titanium carbide, titanium nitride, tantalum carbide, and carbides can be used. Examples of the powder include tungsten. These titanium carbide powders may be used alone or in combination of two or more.

The mixing ratio of the above-mentioned components is "9% of Al ₂ O ₃ component powder when the total amount of the sintering raw material is 100% by weight.
0 to 50% by weight, and "powder such as titanium carbide is 10
.About.50% by weight ". The ratio of Al ₂ O ₃ component powder is 90
When the content is higher than 10% by weight, the average particle size of all the components constituting the sintered body exceeds 1 μm and becomes large, and the transverse rupture strength, which is an index of toughness, decreases. On the other hand, if it is less than 50% by weight, the densification of the sintered body is not sufficient, the relative density becomes small, and the transverse rupture strength becomes lower than that in the case where the Al ₂ O ₃ component powder exceeds 90% by weight. Further, the Al ₂ O ₃ component powder by changing puts up its half of the ZrO ₂ powder, Al ₂
If the growth of O ₃ particles is suppressed and the other components and their amounts are similar to each other, the hardness and transverse rupture strength of the sintered body can be further improved. However, when the amount exceeds ZrO ₂
If the powder is replaced with powder, the mechanical strength of the sintered body such as transverse rupture strength decreases, which is not preferable.

Examples of the above-mentioned "sintering aid" include magnesium oxide, calcium oxide, silicon oxide, nickel oxide, chromium oxide, dysprosium oxide, yttrium oxide and the like, and these can be used without particular limitation.
In particular, magnesium oxide is preferable because it has an effect of suppressing the crystal growth of alumina. In the present invention, the sintering aid is used in an amount of 0.2 to 5.0% by weight based on 100% by weight of the sintering raw material. When the amount of the sintering aid used is less than 0.2% by weight, the densification of the sintered body is not sufficient, the relative density is significantly reduced, and the hardness and the transverse rupture strength are also significantly reduced. Also,
If the amount is more than 5.0% by weight, the average particle size of all the components forming the sintered body becomes large, and the transverse rupture strength and the like decrease, resulting in poor toughness. The amount of sintering aid used is especially 0.5
The range of up to 1.5% by weight is preferable, and in this range, hardness, transverse rupture strength and the like are more excellent. It is preferable that all particles constituting the sintered body are finer, but in the present invention, those having an average particle size of 1.0 μm or less in a particle size range of 0.3 to 1.2 μm, particularly, Preferably, the particle size is 0.
Those having an average particle size of 3 to 1.0 μm and an average particle size of 0.7 μm or less can be used.

As a raw material for forming the above "coating film",
IVa, Va, and VI similar to the constituents of the sintered body
In addition to carbides, nitrides, and carbonitrides of group a elements, Al ₂ O ₃ ,
AlON is mentioned, and these are preferable because they have excellent compatibility with the sintered body, the coating film does not peel off from the surface of the sintered body, and the hardness is high and the abrasion resistance is excellent. At least one coating film is enough, but each layer has a thickness of 2μ
m or less, particularly 1 μm or less, and the total thickness is 0.2 to 10
It is preferably composed of a plurality of layers having a thickness of not more than μm, and if the thickness of each layer is such a thin layer as described above, the coating film does not peel off even when used for high-speed cutting. The innermost layer is Al ₂ O ₃ or Al with a thickness of 1 μm or less.
Forming a coating film consisting of a titanium nitride layer having a thickness of 0.5 μm or less for the ON layer and the outermost layer has excellent compatibility with a sintered body mainly composed of Al ₂ O ₃ and has an extremely high surface hardness. More preferred is a ceramic cutting tool that has a high and grain boundary glass phase free surface.

[0011]

[Function] When cutting high hardness materials such as carburized and hardened steel and die steel, especially when cutting at high speed
It becomes high temperature of more than 000 ℃. For this reason, the hardness and strength of ordinary ceramic tools may drop sharply, resulting in severe wear and, in some cases, chipping.
Tool life is short. In the present invention, by combining a specific sintering raw material with a specific amount of a sintering aid, the average particle diameter of most of the component particles constituting the structure can be set to 1 μm or less, preferably 0.7 μm. It is possible to obtain an alumina-based sintered body having extremely high hardness and strength. The thickness of each layer on the surface of this sintered body is 2 μm or less, preferably 1 μm or less.
By forming at least one coating film having a thickness of μm or less, a ceramic suitable for a cutting tool of a high hardness material having a coating film having excellent adhesion to a base material and having high hardness, strength, etc. be able to. Further, the cutting tool using the ceramic of the present invention, which is composed of the sintered body and the coating film, maintains high hardness and strength even when exposed to a high temperature in the above high-speed cutting, and the cutting of the CBN tool is performed. It can be sufficiently used even at a cutting speed of 150 mm / min or more, which is a speed range.

[0012]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. (1) Production of sintered body Al ₂ O ₃ component: Al ₂ O ₃ powder having an average particle size of 0.5 μm, ZrO ₂ powder having an average particle size of 0.5 μm, titanium carbide, etc .: TiC and TiCN having an average particle size of 1 μm , TaC, W
C powder, sintering aid: MgO having an average particle size of 0.2 μm,
Y ₂ O ₃ and Dy ₂ O ₃ powder having an average particle size of 0.9 μm, and the above components were mixed at the ratios shown in Table 1 (implementation product) and Table 2 (comparative product), and after crushing with an attritor to strong crushing. , Pressure 200kg / c
Hot pressing was performed at m ² and a temperature of 1700 to 1800 ° C.
The obtained sintered body was ground into a predetermined shape to produce a chip for a cutting test (using products 2, 4, 5 and 7). In addition, by using a test piece cut out from the above-mentioned sintered body, the average particle size, relative density, hardness (measurement method: Vickers hardness, load 10 Kgf), transverse rupture strength (measurement method: JISR-
1601) was measured. The results are shown in Tables 1 and 2 (HV in each table represents the above hardness). In Table 2, * means that the value is out of the numerical limit range.

[0013]

[Table 1]

[0014]

[Table 2]

According to the results shown in Table 1, in all the sintered bodies used in the ceramic tool of the present invention, the average particle size of all the components is 1 μm or less, and the relative density is as high as 99% by weight or more. In addition, it is clear that both hardness and transverse rupture strength are excellent. In particular, when the amount of the sintering aid used is 1% by weight, it is more excellent than when the amount used is 2% by weight or more. on the other hand,
According to the results of Table 2, when Al ₂ O ₃ or MgO exceeds the upper limit (Comparative products 1 and 4), the average particle size of all components of the sintered body exceeds 1 μm, and the hardness and the transverse rupture strength are Inferior, also MgO
When is less than the lower limit (Comparative product 3), it can be seen that all of the relative density, hardness, and transverse rupture strength are significantly reduced. In other cases, the hardness and the transverse rupture strength are lowered, and none of the comparative products can be used as a sintered body for obtaining the ceramic tool of the present invention.

(2) Manufacture of ceramic tool Table 3 is prepared on the chip surface for cutting test prepared in (1) above.
The coating films shown in (Examples) and 4 (Comparative Examples) were coated with known CVs.
It was formed by the D method or PVD method, and a cutting test was performed under the following conditions. Work Material: SCM415 Carburized and Quenched Material (Hv = 850-70
0 Kg / mm ² ) Tip shape: TNGN332 Cutting speed: 200 m / min Feed: 0.1 mm / rev Depth of cut: 0.3 mm Chamfer: 0.2 mm x -25 ° The work material was cut for 30 minutes under the above conditions. After that, the average flank wear amount (V _B wear amount) was measured. The results are shown in Table 3.
And 4 are shown. In Table 4, * indicates that the value is out of the numerical limit range.

[0017]

[Table 3]

[0018]

[Table 4]

From the results shown in Table 3, it can be seen that the ceramic tools of the present invention do not peel off the coating film and have a small amount of V _B wear in high-speed cutting of high hardness materials. In addition, the innermost layer has a thickness of 0.7 μm of Al ₂ O.
_3, in the case when the coating film using TiN having a thickness of 0.2μm on the outermost layer and the covering film is TiC, it can be seen that particularly excellent in abrasion resistance. On the other hand, according to the results in Table 4, the total thickness of the coating film is less than the lower limit (Comparative Example 1), exceeds the upper limit (Comparative Example 2), and the thickness of one layer exceeds the upper limit. In Comparative Example 3, the amount of V _B wear was about twice that of the Examples, and in Comparative Examples 2 and 3, peeling of the coating film occurred, and in Comparative Example 2, the peeled area was particularly large. large. Incidentally, for reference, in the commercially available product similarly subjected to the cutting test as Comparative Example 4, the wear amount was larger than that of the Comparative Example of the present invention, and not only the peeling but also the breakage of the tip occurred, which was more than that of the ceramic tool of the present invention. It can be seen that the performance is remarkably inferior.

[0020]

EFFECTS OF THE INVENTION The ceramic tool for cutting high hardness material of the present invention has the average particle diameter of the constituent particles of the ceramic body being a specific fine particle, and has a coating film of a specific thickness.
It has excellent hardness and strength, and even when high-hardness materials such as carburized and hardened steel and die steel are cut at high speed, the excellent hardness and strength are maintained, and it can be used as a substitute for CBN tools.

Claims (5)

[Claims] 1. A ceramic tool for cutting comprising a sintered body obtained by mixing a sintering raw material and a sintering aid and firing the mixture, and at least one coating film formed on the surface of the sintered body. In the above, the average particle diameter of all components constituting the sintered body is 1 μm or less, and the sintering raw material is 90 to 50% by weight of Al ₂ O ₃ component powder when the total amount is 100% by weight. And 10
~ 50 wt% IVa, Va, VIa group carbides,
One or more powders of nitride and carbonitride, wherein the sintering aid is 0.2 with respect to 100% by weight of the sintering raw material.
˜5.0 wt%, and the coating film is IVa,
Va, VIa group element carbides, nitrides, carbonitrides, Al ₂
Consists of O ₃ or AlON, and the thickness of each layer is 2 μm
A ceramic tool for cutting a high hardness material, which has a total thickness of 0.2 to 10 μm. 2. The average particle size of all components constituting the sintered body is 0.7 μm or less, and the thickness of each layer of the coating film is 1 μm or less.
The ceramic tool for cutting a high hardness material according to claim 1, wherein the ceramic tool has a thickness of not more than μm. 3. The total amount of the Al ₂ O ₃ component powder is 1.
95% to 50% by weight of Al ₂ O ₃ when defined as 00% by weight
A ceramic tool for cutting a high hardness material according to claim 1 or 2, which comprises powder and 5 to 50% by weight of ZrO ₂ powder. 4. The coating film comprises a plurality of layers, the innermost layer is made of Al ₂ O ₃ or AlON and has a thickness of 1 μm or less, and the outermost layer is made of TiN and has a thickness of 0.5 μm or less. The ceramic tool for cutting high hardness material according to claim 1, 2 or 3, characterized in that. 5. The average flank wear amount according to the following test conditions is 0.2 mm or less, 1.
A ceramic tool for cutting a high hardness material according to 2, 3 or 4. Flank wear test conditions: Work material; SCM415 carburized and hardened material (Hv = 700 to 850 Kg / mm ² ), cutting speed; 250 m /
Minute, feed: 0.1 mm / rev, notch: 0.3 mm,
Chamfer; 0.2mm × -25 °