JP2001080953A - Ceramic sintered compact and coated ceramic sintered compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the hardness, strength and toughness from a low- temperature region to a high-temperature region of sintered ceramics by incorporating a specific ratio of aluminum nitride and a specific ratio of at least one kind of titanium compounds expressed by a formula expressed by specific relations of Ti, C, N and O. SOLUTION: This ceramic sintered compact contains the Ti compound expressed by the formula: Ti (Cx, Ny and Oz). (In the formula, (x), (y) and (z) denote the respective atom ratios of C, N and O and x+y+z=1, 0<=x<=0,4, 0.6<=y<=1.0, 0<=z<=0.05). The content of the aluminum nitride is 1 to 25 vol.% and the content of the titanium compound is 75 to 99 vol.%. The titanium compound of the high-nitrogen content contained in the ceramic sintered compact and the coated ceramic sintered compact acts to suppress the friction resistance and reaction with ferrous materials, or the like, in the high-temperature region and, on the other hand, the aluminum nitride ats to enhance thermal conductivity. When the sintered compact is used as a cutting tool, the wear resistance and chipping resistance are excellent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic sintered body containing a compound of aluminum nitride and titanium, and a coated ceramic sintered body in which a hard film is coated on a substrate surface of the ceramic sintered body. In particular, the present invention relates to a ceramic sintered body and a coated ceramic sintered body containing a titanium compound as a main component.

[0002]

2. Description of the Related Art In general, ceramic sintered bodies are roughly classified into oxide ceramic sintered bodies and non-oxide ceramic sintered bodies. Some of these ceramic sintered bodies are practically used as tools such as cutting tools and wear-resistant tools. Ceramic sintered bodies used as tools are required to have high hardness and high toughness, especially for cutting tools used under severe conditions of high load and high temperature, such as thermal shock resistance and high fracture toughness. Characteristics are also required. As a one-way ceramic sintered body developed from such a demand, there is a ceramic sintered body containing aluminum oxide and a non-oxide such as titanium carbide and titanium nitride. 63-225579 and JP-A-Hei 1
No. 179778. As a typical ceramic sintered body, there is Japanese Patent Application Laid-Open No. 61-295271.

[0003]

Japanese Patent Application Laid-Open No. 63-225579 discloses a ceramic sintered body which can be used for tools such as cutting tools and wear-resistant tools.
4.5 wt% TiC and 0.5 to 40 wt% Al ₂ O ₃ to 5
A ceramic sintered body in which -40% by weight of SiC whiskers are uniformly dispersed and sintered is disclosed. JP-A-1-179778 discloses that 9 to 45% by weight of aluminum oxide, 0.5 to 8% by weight of at least one of oxides of Mg, Y, and Zr, and 51 to 90% by weight are provided. Patent Document 1 discloses a coated ceramic sintered body in which a ceramic sintered body composed of% titanium carbide is used as a base material, and a hard film of a Ti compound is coated on the base material surface. The ceramics sintered bodies disclosed in both of these publications have a problem that thermal conductivity is reduced, and thermal shock resistance and thermal crack resistance are inferior because oxides such as aluminum oxide are added in a large amount. In particular, in the latter case, since the SiC whiskers increase the reactivity with the iron-based material, there is a problem that the wear resistance is also reduced.

Japanese Patent Application Laid-Open No. 61-295271, which is another example of a ceramic sintered body, discloses B
e, Mg, Ca, Sr, Al, Ga, In, Tl, S
1 to 15% by weight of at least one dispersed phase in c, Y, lanthanoid oxide or their mutual solid solution
And the remaining (Ti, M) carbides, carbonitrides, carbonates,
Hard phase of carbonitride (where M = Zr, Hf, V, T
a, a high hardness sintered body based on a titanium compound comprising at least one metal element of Nb). The titanium compound-based high-hardness sintered body disclosed in the publication has a high carbon content in the hard phase, and thus has a high hardness and excellent wear resistance in a low temperature region, but has a high wear resistance in a high temperature region. Has a problem that friction resistance and reactivity with iron-based materials are increased, and conversely, wear resistance is reduced. In particular, when using conventional ceramics cutting tools to cut ductile cast iron with high strength and toughness compared to general cast iron, wear and cracks due to thermal cracks will occur. There is a problem that the life is shortened.

The present invention is directed to a ceramic sintered body and a coated ceramic sintered body which have solved the above-mentioned problems. More specifically, the present invention relates to a titanium compound containing a large amount of nitrogen and aluminum nitride having excellent thermal conductivity. Evenly disperse,
And by making it a dense sintered body, while increasing the hardness, strength, toughness in the low to high temperature range,
It is an object of the present invention to provide a ceramic sintered body and a coated ceramic sintered body having excellent thermal shock resistance and thermal crack resistance.

[0006]

The inventor of the present invention has studied the workability of ductile cast iron. First, Al ₂ O ₃ in which titanium carbonitride is added to conventionally used aluminum oxide. As a result of conducting a cutting test of ductile cast iron using sintered ceramics as a cutting tool,
Being affected by the nitrogen content in the titanium carbonitride, specifically, the nitrogen content in the titanium carbonitride, ie, N / (N
It was found that when + C) ≧ 0.6, the reactivity with iron was sharply improved. Secondly, it has been found that a cutting tool used for cutting ductile cast iron is preferably made of a material having high thermal conductivity, and therefore, aluminum nitride is preferred over aluminum oxide. Thirdly, they have found that there is an optimal relationship between the ratio between aluminum nitride and a titanium-containing compound and the nitrogen content in titanium carbonitride. Based on these findings, the present invention has been completed.

That is, the ceramic sintered body of the present invention comprises 1 to 25% by volume of aluminum nitride and Ti (C
(x, Ny, Oz) in an amount of 75 to 99% by volume of at least one titanium compound.
(However, Ti represents a titanium element, C represents a carbon element, N represents a nitrogen element, O represents an oxygen element, x, y, and z represent respective atomic ratios of C, N, and O, and x + y + z = 1, 0 ≦ x ≦
0.4, 0.6 ≦ y ≦ 1.0, satisfying the relationship of 0 ≦ z ≦ 0.05)

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The ceramic sintered body of the present invention comprises:
~ 25% by volume aluminum nitride and 75 ~ 99% by volume
Of a titanium compound and an unavoidable impurity, or 1 to 25% by volume of aluminum nitride and 7
The total of the two substances in a volume ratio of 5 to 99 volumes of the titanium compound may be 50% by volume or more, preferably 80% by volume or more, and the remaining third substance may be contained. As the titanium compound at this time, at least one of titanium nitride, titanium carbonitride, titanium nitride oxide, and titanium carbonitride
It is preferable to use titanium nitride and / or titanium carbonitride, since frictional resistance is suppressed, and damage caused by chips when used as a cutting tool is suppressed. That is.
The volume ratio between the aluminum nitride and the titanium compound is:
When the content of aluminum nitride is less than 1% by volume, the thermal conductivity possessed by aluminum nitride itself is difficult to exhibit, and when the content of aluminum nitride exceeds 25% by volume, the toughness and strength are significantly reduced. .

Specific examples of the third substance contained in addition to the aluminum nitride and the titanium compound include, for example, carbides, nitrides, and the like of elements of groups 4a, 5a, and 6a of the periodic table.
Oxides, oxides of Group 2a and 3a elements of the periodic table and their mutual solid solutions, silicon carbide, silicon nitride, aluminum oxide, (Ti, Al) N, (Ti, Al) (C,
N), (Ti, Al) C and (Ti, Al) (N, O). The third substance is different depending on the composition, but is preferably 30% by volume or less of the whole sintered body.
It is preferable to select a composition component according to a use or a shape. In particular, it includes nitrides, carbonitrides, oxynitrides, oxycarbonitrides, carbides, nitrides, tungsten carbide, tantalum nitride, magnesium oxide, Sc, and Y containing Ti and Al, which are elements of Group 4a of the periodic table. At least one selected from oxides of rare earth elements and mutual solid solutions thereof;
When it is composed of a seed, the third substance is uniformly dispersed in the sintered body, so that a dense sintered body can be easily obtained, and the heat shock resistance and the thermal crack resistance are remarkably excellent. That is. These aluminum nitrides,
There is no problem even if the titanium compound and the third substance consist of a stoichiometric composition or a non-stoichiometric composition.

The ceramic sintered body of the present invention having such a structure is used as a base material, and at least a part of the surface of the base material is made of a group 4a, 5a, or 6a element of the periodic table, a carbide of Al or Si, or nitrided. , Oxides and their mutual solid solutions, or coated with a hard film composed of one single layer selected from diamond, diamond-like carbon, cubic boron nitride, and hard boron nitride, or a laminate of two or more types The coated ceramic sintered body is preferable because wear resistance, durability and long life are achieved.

[0011] At this time, the coating structure including the hard film may be such that the hard film is directly coated adjacent to the base material, or a single material made of a substance other than the hard film is provided between the hard film and the base material. It is also preferable to adopt a film configuration in which a layer or a multilayer intermediate layer is formed. When the intermediate layer is made of a metal or an alloy, specifically, for example, a single layer of one of the metals of the 4a, 5a, and 6a group of the periodic table, such as titanium, tantalum, and tungsten, silicon, and alloys thereof Or 2
A typical example is a case of a multi-layer composed of more than one kind. This intermediate layer is preferable because it exhibits an effect of improving adhesion and adhesion between the hard film and the base material, and promoting nucleation for forming the hard film and promoting crystallization of the hard film. . In the case of the film configuration in which the intermediate layer is interposed, the metal element constituting the intermediate layer may be diffused into the hard film, and in this case, the adhesion between the intermediate layer and the hard film is further improved. This is preferable because it is excellent.

[0012] Specifically, these coating structures are, for example, TiC, TiN, TiCN, (Ti, Al) N, Al ₂
A single layer of O ₃ , diamond, diamond-like carbon, cubic boron nitride, hard boron, TiN—Al ₂
O ₃ —TiN, Ti (C, N) —TiC—Al ₂ O ₃ , T
One type of multilayer among iN- (Ti, Al) N, Si-diamond, W-diamond and TiN-cBN can be mentioned as a representative example.

At this time, the thickness of the hard film and the thickness of the intermediate layer in the case where the intermediate layer is interposed are selected depending on the constitution of the coating, the film quality, application, shape, etc. of the hard film and the intermediate layer. Is preferable. Among them, the hard film has a thickness of 0.5 to 20 μm, preferably, in order to bring out the effects of abrasion resistance, durability and long life and not to decrease the peeling resistance of the film. 1 to 10 μm
That is to say, it is a film thickness. Further, the intermediate layer has a thickness of 2 μm or less, preferably 1 μm or less, in order to bring out the above-mentioned functions and effects and to shorten the manufacturing process.

The ceramic sintered body and the coated ceramic sintered body of the present invention are more resistant to thermal shock than conventional aluminum oxide-based ceramic sintered bodies because of their practical use. It can be practically used for applications requiring thermal crack resistance and high thermal conductivity. The ceramic sintered body and the coated ceramic sintered body of the present invention are preferably used as a tool member among applications, as a cutting tool among tool members, and used as a cutting tool for cutting cast iron among cutting tools. When done
Toughness, abrasion resistance, thermal shock resistance, thermal crack resistance,
This is particularly preferable because high thermal conductivity is exhibited and the life is extended.

The ceramic sintered body and the coated ceramic sintered body of the present invention can be manufactured by a conventional method of manufacturing a ceramic sintered body by powder metallurgy and a conventional method of coating a hard film. Specifically, for example, using a mixed and crushed powder of a predetermined composition component, after molding into a powder molded body of a predetermined shape by die molding, extrusion molding, injection molding, cast molding, and machining, and then vacuum or A ceramic sintered body can be produced by heating and sintering in a non-oxidizing atmosphere. Using this ceramic sintered body as a base material, a conventional chemical vapor deposition method (hereinafter, referred to as “CVD”) in a state of a sintered surface or a state in which the surface is subjected to machining or / and corrosion treatment.
Method), a physical vapor deposition method (hereinafter, referred to as a “PVD method”), and a method of combining one or two or more types represented by a plasma CVD method to coat a hard film on a substrate surface and fire the coated ceramic. A unity can be made.

[0016]

The ceramic sintered body and the coated ceramic sintered body of the present invention have a high nitrogen content titanium compound contained in the sintered body, and exhibit a high frictional resistance and a reaction with an iron-based material in a high temperature region. Aluminum nitride, which is another essential component, has the effect of increasing thermal conductivity, and the uniform dispersion of aluminum nitride enhances the synergistic effect of both components, especially in high-temperature regions. It improves abrasion, toughness, thermal shock resistance, and thermal crack resistance.

[0017]

Example 1 Titanium nitride, titanium carbide, various types of titanium carbonitride and titanium carbonitride having an average particle size of about 1.3 to 1.8 μm, and aluminum nitride having an average particle size of about 2.5 μm The powder was used as a starting material, and weighed into the composition components for the present invention products 1 to 10 and comparative products 1 to 4 shown in Table 1. Samples of the various composition components shown in Table 1 were charged into a ball mill pot together with an acetone solvent and a cemented carbide ball, and wet-mixed and pulverized. To each of the mixed powders thus obtained, a paraffin wax as a molding aid was added in an amount of 5% by weight over an outer periphery, mixed and dried, and then, using a mold, a SNGN120408 according to ISO standard was used.
It was molded into a shape to obtain a powder compact. After pre-sintering these powder compacts to remove paraffin wax, sintering was carried out in an argon atmosphere at 1800 ° C. for 1 hour, and further kept in an argon atmosphere at 1000 atm at 1700 ° C. for 1 hour. A hot isostatic pressure (hereinafter, referred to as “HIP”) treatment is performed according to conditions, and the products 1 to 5 of the present invention
10 and Comparative products 1-4 were obtained.

The products 1 to 10 of the present invention and the comparative products 1 to 4 thus obtained were tested for reactivity with cast iron, Vickers hardness,
Table 2 shows the characteristics of the sintered body such as toughness and thermal conductivity.
It was shown to. The reactivity with the cast iron at this time was determined by superimposing each sample on a cast iron plate and performing a reaction test by hot pressing at about 1300 ° C. under a pressure of about 2.5 kPa. The reactivity was determined by observing the diffusion distance in which the metal component contained in the cast iron was diffused to the sample side, and discriminating between large, medium and small diffusion distances.

Next, products 1 to 10 of the present invention and comparative product 1
A cutting test was performed for the samples No. to No. 4. In the cutting test, the work material: FCD700, cutting speed: 400 m / min, cutting depth: 2 mm, feed: 0.3 mm / rev, cutting time:
3min, Cutting oil: Use water-soluble cutting oil, Tool shape: SN
GN120408, honing: 0.15x-25 degrees,
A continuous turning test was carried out according to
_N ) was determined, and the results are shown in Table 2. Work material: FCD600, cutting speed: 150 m / min, depth of cut: 1.5 mm, initial feed: 0.2 mm / rev, tool shape: SNGN120408, honing: 0.15
Milling test by dry method at × -25 degrees, feed is 0.03mm if there is no breakage at 1 pass
/ Rev, and the maximum feed when the tool was broken was determined. The results are also shown in Table 2.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

[Table 4]

[0024]

[Test 3] Using the products 1 to 3 of the present invention obtained in the test 1 and the comparative product 1 and the products 14 and 16 of the present invention obtained in the test 2 as base materials, a conventional method was applied to the surface of each base material. The hard films shown in Table 5 were coated by a CVD method and a PVD method (ion plating method) performed from the above to obtain a coated ceramic sintered body. The hard films shown in Table 5 were coated as a first layer, a second layer, and a third layer from the substrate side toward the surface. The base material of the inventive product 17 shown in Table 5 is the inventive product 1
The base material of the product 18 of the present invention is the product 2 of the present invention and the product 1 of the present invention.
The base material 9 is the product 3 of the present invention, the base material of the product 20 is the product 16 of the present invention, and the base material of the product 21 is the product 14 of the present invention.
As a base material of Comparative Product 5, Comparative Product 1 was used. The hard film thickness and the hard film composition of the inventive products 17 to 21 and the comparative product 5 thus obtained were determined by X-ray diffraction and scanning electron microscope (SEM).
And the results are shown in Table 5. In addition, a continuous turning test and a milling test were performed on the products 17 to 21 of the present invention and the comparative product 5 in the execution test 1, and the maximum feed to the boundary wear amount and the fracture were obtained, respectively. .

[0025]

[Table 5]

[0026]

The ceramic sintered body and the coated ceramic sintered body of the present invention have lower reactivity with an iron-based material (affinity) than a conventional titanium compound-based ceramic sintered body which is the closest approximation. Inferiority), high toughness and high thermal conductivity. As an effect, it shows a tendency to excel in abrasion resistance, thermal shock resistance, thermal crack resistance, and thermal plastic deformation, especially in the high temperature range. In this case, the wear resistance and the fracture resistance are remarkably excellent. From this, the ceramic sintered body and the coated ceramic sintered body of the present invention are a turning tool, a milling tool, a drill, a cutting tool represented by an end mill, a slitter, a push, a guide, a nozzle,
Balls (pen balls, ball valves, etc.), cutting tools,
Wear-resistant tools represented by cutting tools, engine parts, rotor parts, machine tool parts represented by precision machine parts, bearings (balls, cages, etc.), sliding tool parts represented by sliders, furnace jigs Thus, the present invention can exert an effect as a structural tool component represented by a molding jig.

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[Procedure amendment]

[Submission date] September 22, 1999 (September 9, 1999
2)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The ceramic sintered body of the present invention comprises:
~ 25% by volume aluminum nitride and 75 ~ 99% by volume
Of a titanium compound and an unavoidable impurity, or 1 to 25% by volume of aluminum nitride and 7
The total of the two substances in a volume ratio of 5 to 99 volumes of the titanium compound may be 50% by volume or more, preferably 70% by volume or more, and the remaining third substance may be contained. As the titanium compound at this time, at least one of titanium nitride, titanium carbonitride, titanium nitride oxide, and titanium carbonitride
It is preferable to use titanium nitride and / or titanium carbonitride, since frictional resistance is suppressed, and damage caused by chips when used as a cutting tool is suppressed. That is.
The volume ratio between the aluminum nitride and the titanium compound is:
When the content of aluminum nitride is less than 1% by volume, the thermal conductivity possessed by aluminum nitride itself is difficult to exhibit, and when the content of aluminum nitride exceeds 25% by volume, the toughness and strength are significantly reduced. .

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction contents]

[0020]

[Table 1]

Claims (10)

[Claims] 1. An aluminum nitride containing 1 to 25% by volume of
A ceramic sintered body containing 75 to 99% by volume of at least one titanium compound represented by i (Cx, Ny, Oz). (Where Ti is a titanium element, C is a carbon element, N is a nitrogen element, O is an oxygen element, x, y, z
Represents the atomic ratio of each of C, N, and O, and x + y + z =
1,0 ≦ x ≦ 0.4,0.6 ≦ y ≦ 1.0,0 ≦ z ≦
Satisfies the relationship of 0.05) 2. The method according to claim 1, wherein the titanium compound is titanium nitride and / or titanium nitride.
2. The ceramic sintered body according to claim 1, comprising titanium carbonitride. 3. A total of 50% by volume or more of said aluminum nitride and said titanium compound, and nitrides, carbonitrides, oxynitrides, oxycarbonitrides containing Ti and Al, and 4 of the periodic table.
A third substance consisting of at least one selected from the group consisting of carbides, nitrides, oxides of Group a, 5a, and 6a elements, oxides of Group 2a elements of the periodic table, and mutual solid solutions thereof is used.
3. The ceramic sintered body according to claim 1, wherein the ceramic sintered body contains at most 30% by volume. 4. The third substance is a nitride containing Ti and Al, a carbonitride, a nitride oxide, a carbonitride, 4a of the periodic table.
4. The ceramic sintered body according to claim 3, comprising at least one selected from the group consisting of carbides, nitrides, tungsten carbide, tantalum nitride, magnesium oxide, and mutual solid solutions thereof. 5. The sintered body according to claim 3, wherein the third substance is
5. The ceramic sintered body according to claim 3, comprising 30% by volume or less. 6. A ceramic sintered body according to any one of claims 1 to 5, wherein the ceramic sintered body is used as a tool member. 7. The cutting tool according to claim 6, wherein said tool member is a cutting tool.
3. The ceramic sintered body according to item 2. 8. The ceramic sintered body according to claim 7, wherein said cutting tool is for processing cast iron. 9. The ceramic sintered body according to any one of claims 1 to 8 as a base material, wherein at least a part of the surface of the base material includes a 4a, 5a, 6a group element of the periodic table, Al , Si
Carbides, nitrides, oxides and their mutual solid solutions,
Alternatively, a coated ceramic sintered body coated with a hard film composed of one kind of single layer selected from diamond, diamond-like carbon, cubic boron nitride and hard boron nitride, or a laminate of two or more kinds. 10. The hard film is selected from titanium carbide, titanium nitride, titanium carbonitride, aluminum oxide, a composite nitride containing titanium and aluminum, a composite carbonitride, a composite carbonitride, and a composite carbonitride. The coated ceramic sintered body according to claim 9, wherein the coated ceramic sintered body is formed of one selected single layer or two or more layers.