JP2003267787A - beta'-SIALON-BASED CERAMIC TOOL AND ITS PRODUCTION METHOD - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a β'-sialon-based ceramic tool having improved wear resistance, defect resistance and chipping resistance during cutting and also to provide a production method thereof. <P>SOLUTION: The β'-sialon-based ceramic tool with excellent wear resistance, defect resistance and chipping resistance containing a β'-sialon represented by the formula: Si<SB>6-</SB>ZAlZOZN<SB>8-</SB>Z (0<Z≤4.2) as its main component, which includes the β'-sialons with both a low Z value of 0.03≤Z<1.0 and a high Z value of 1.1≤Z<4.0, is obtained by adding a coarse powder of aluminum oxide to a premixed powder of silicon nitride, aluminium nitride and yttrium oxide. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a β'-sialon-based ceramics tool mainly used as a tool for high speed cutting of cast iron and heat resistant alloys.

[0002]

2. Description of the Related Art Generally, β'-sialon (general formula Si
_6-Z Al _Z 0 _Z N _8-Z , 0 <Z ≦ 4.2) -based ceramics tools have better wear resistance than alumina nitride-based ceramics tools because they contain alumina, but strength and Inferior in fracture resistance due to low toughness and thermal conductivity,
This tendency becomes remarkable as the amount of alumina added increases.
Therefore, many proposals for improvement have been made in terms of both wear resistance and fracture resistance.

A typical example of prior art relating to strength improvement measures for β'-sialon-based ceramics is disclosed in Japanese Patent Publication No. 8-5.
10965, JP-A-5-208869 and JP-A-8-337477.

[0004]

Among the prior art relating to the strength improvement of β'-sialon-based ceramics, Japanese Patent Publication No.
-510965 discloses that β'- is 50 vol% or more.
A metal cutting insert made of ceramics containing sialon and having a Z value limited to a range of 1.0 <Z <3.0 is described. The β'-sialon-based ceramics of the present description has a good balance between wear resistance and fracture resistance in cutting under specific conditions, but lacks general versatility, and either wear resistance or fracture resistance is insufficient. There is a problem to say.

Japanese Unexamined Patent Publication (Kokai) No. 5-208869 discloses a silicon nitride-based cutting tool in which both crystal phases of α-silicon nitride having fine grains and equiaxed crystal and β'-sialon having fine grained columnar form are combined. ing. Although the tool described in the present invention becomes tough by the inclusion of α-silicon nitride, the Z value of β′-sialon coexisting with α-silicon nitride is inevitably low, so that the wear resistance is certainly lowered. There is a problem to say.

Further, Japanese Patent Laid-Open No. 8-337477 discloses a matrix containing β'-sialon as a main component.
0 to 99% by weight, and R _Z (M′M ″) _2-X O _7-2X (R is a rare earth, M ′ is at least one of the elements in Group 4a of the periodic table).
Seed, M ″ is at least one of the elements of the periodic table 2a, 6a, 7a, and 8a, and a particle containing a complex oxide as a main component represented by −6 <X <1, 0 ≦ Z <1). The β'-sialon-based sintered body according to the present disclosure is characterized by wear resistance, fracture resistance, and thermal shock resistance by crystallizing the grain boundary phase. However, the effect is small, and there is a problem that it is difficult to simultaneously improve wear resistance and fracture resistance.

The present invention improves the hardness, strength, and toughness of β'-sialon-based ceramics, and improves wear resistance during cutting,
It is an object of the present invention to provide a β'-sialon-based ceramics tool with improved chipping resistance and chipping resistance.

[0008]

The present inventors have found that Si _6-Z
A study was conducted on improvement of life and reliability of a β'-sialon-based ceramics tool containing β'-sialon represented by Al _Z 0 _Z N _8-Z (0 <Z≤4.2) as a main component. , Β'-sialon-based ceramics tool contains a small amount of alumina, that is, β'-sialon with a low Z value, and a large amount of alumina, that is, β'-sialon with a high Z value, is used as a cutting tool. In this case, it was found that the wear resistance, the fracture resistance and the chipping resistance can be compatible at a high level.

As a method for producing the β'-sialon-based ceramics tool of the present invention, a premixed powder obtained by removing a part or all of the aluminum oxide component from the raw material powder is prepared in advance, and the premixed powder is made into coarse particles. If the aluminum oxide powder is added and mixed and then sintered, the Z value is low.
The present invention has been completed based on the finding that a uniform composite structure of sialon and β′-sialon having a high Z value can be obtained.

In the present invention, the β'-sialon-based ceramics tool is 50 '% by weight or more of β'-sialon,
The remainder is a β'-sialon based ceramics tool consisting of ceramics, glass phase, metal and / or unavoidable impurities. Among them, other than β'-sialon, Si, Al, Mg, Ca, Li, rare earths, 4a, 5
Carbides, nitrides, oxides, borides of a and 6a group elements,
And one or more kinds of β'-sialon-based ceramics tools selected from these mutual solid solutions have high heat resistance and are preferable.

Specifically, M _w (SiAl) ₁₂ (ON)
₁₆ [However, M is rare earth, Li, Mg, Ca, Hf, T
i, one or more elements selected from Zr, (0 <w ≦
2)] represented by α′-sialon, α-Si ₃ N ₄ , β
_{-Si 3 N 4, Al 2 O} 3, AlON, AlN, SiAl 3
O ₂ N ₃ , SiAl ₄ O ₂ N ₄ , MgO, CaO, Y ₂ O ₃ ,
Yb ₂ O ₃ , Dy ₂ O ₃ , La ₂ O ₃ , SiO ₂ , ZrO ₂ , H
fO ₂ , TiC, TiN, TiCN, TiB ₂ , WC, Z
r (N, O), ZrN, HfN, TaC, TaN, Ta
These include CN, NbC, NbN, NbCN, and their mutual solid solutions. Note that rare earths represent Sc, Y, and lanthanides (atomic numbers 57 to 71).

Β'-sialon is Si_6-ZAl_Z0_ZN
_8-ZSi represented by (0 <Z ≦ 4.2)₃N_Four-SiO₂−
AlN-Al₂0₃System compounds, β-Si₃N_FourTo A
l₂0 ₃． AlN, SiO₂And some grain boundary phase components are solid
It is formed by melting. The β'-sialon of the present invention has a Z value
Is 0.03 ≦ Z <1.0 and 1.1 ≦ Z <4.0
It also contains two types of β'-sialon crystal particles.
Of.

If the Z value of the former is less than 0.03, needle-like crystals of β'-sialon will not be formed, and if it exceeds 1.0, the strength of the crystal will be greatly reduced, resulting in chipping resistance and chipping resistance. Can not be improved. The Z value of the latter is 1.1.
If it is less than 4.0, the wear resistance cannot be improved, and if it exceeds 4.0, it becomes difficult to form β'-sialon, and the strength is significantly reduced, and the strength improving effect by the former is impaired.

Usually, the X-ray diffraction pattern on one crystal plane of β'-sialon has one peak. However, when a large amount of low Z-value β′-sialon crystal particles and high Z-value β′-sialon crystal particles are contained, the X-ray diffraction pattern on one crystal face of β′-sialon has two peaks. Of the two peaks, one peak is the peak of the X-ray diffraction pattern of the low Z value β'-sialon crystal particles, and the other peak is the peak of the X-ray diffraction pattern of the high Z value β'-sialon crystal particles. Is.

The X-ray diffraction pattern of β'-sialon may overlap with the X-ray diffraction pattern of the grain boundary phase or dispersed phase, but β'-
-Because the X-ray diffraction intensity in the (110) plane, (101) plane, or (201) plane of sialon is high, β'-
Even if it overlaps with an X-ray diffraction pattern other than Sialon, it has little effect. Therefore, the β'-sialon (110) plane,
The β′-sialon-based ceramics tool having two peaks in the X-ray diffraction pattern on at least one plane selected from the (101) plane and the (201) plane has higher wear resistance than conventional products. Excellent chipping resistance and chipping resistance.

The β'-sialon-based ceramics tool of the present invention has a low Z value β'-sialon and a high Z value β'-sialon in a weight ratio of low Z value β'-sialon: high Z value β'-. Sialon = 20: 80 to 80:20 is preferable because abrasion resistance, fracture resistance and chipping resistance can be improved in a well-balanced manner.

The β'-sialon-based ceramics can be easily densified by adding a sintering aid. Most of the sintering aid exists as a grain boundary phase after sintering. If the amount of the grain boundary phase is less than 1% by weight, it is difficult to sinter, and if it exceeds 10% by weight, abrasion resistance and thermal shock resistance decrease, so 1 to 10% by weight is preferable. As a grain boundary phase, a rare earth oxide is preferable because it has high high temperature strength. Specifically, Y ₂ O ₃ , Yb
₂ O ₃ , Dy ₂ O ₃ , La ₂ O _3, etc. as the main component, with a small amount of S
It contains iO ₂ and Al ₂ O ₃ . Usually, the grain boundary phase is amorphous (glass phase), but when crystallized, the heat resistance is further improved.

In order to improve the wear resistance and fracture resistance of the β'-sialon-based ceramics tool of the present invention, hard particles other than β'-sialon may be added, and the hard particles added are β'-sialon. If it does not form a solid solution with β after sintering
It exists in the ′ -sialon-based ceramics as a dispersed phase other than β′-sialon particles and the grain boundary phase. When the dispersed phase exceeds 30% by weight, the sinterability and toughness are deteriorated, so that the dispersed phase is preferably 30% by weight or less (including 0).

As the dispersed phase, zirconium oxide,
Nitride, oxynitride, titanium carbide, nitride, carbonitride, hafnium nitride, tungsten carbide, tantalum carbide, nitride, carbonitride, niobium carbide, nitride, carbonitride It is preferable that at least one of these is excellent in heat resistance as well as improved in wear resistance and fracture resistance. Specifically, ZrO ₂ , ZrN, Zr (N, O), Ti
C, TiN, TiCN, HfN, WC, TaC, Ta
N, TaCN, NbC, NbN, NbCN, etc. can be mentioned.

Structurally, in the low Z value β'-sialon matrix containing a large amount of low Z value β'-sialon crystal particles, a high Z value β'-containing a large amount of high Z value β'-sialon crystal particles.
It is preferable that the sialon lumps are dispersed in the form of spots having an average diameter of 5 to 100 μm, because abrasion resistance, fracture resistance and chipping resistance are improved.

The β'-sialon-based ceramic tool of the present invention is formed by CVD, PVD, TiN, TiCN, Al ₂
The life can be further extended by coating with O ₃ , TiAlN or the like.

The β'-sialon-based ceramics tool of the present invention is obtained by, for example, granulating two kinds of mixed powders having Z values of 0.1 and 4.0, mixing them, and press forming,
Obtained by sintering. However, the use of the following production method is preferable because the β′-sialon crystal particles having a low Z value and a high Z value can be uniformly and finely dispersed, and thus both the wear resistance and the fracture resistance are significantly improved.

Of oxides of silicon nitride, aluminum nitride and rare earths and, if necessary, fine-grained aluminum oxide, carbides of group 4a, 5a and 6a elements of the periodic table, nitrides, oxides, borides, and mutual solid solutions thereof. 1 selected from
After mixing seeds or more to obtain a premixed powder, and mixing a coarse-grained aluminum oxide powder having an average particle diameter of at least twice the average particle diameter of the premixed powder, 1400 to 2000 in a nitrogen atmosphere. Low Z value β'- when sintered at a temperature of ℃
Sialon crystal particles and high Z value β'-sialon crystal particles can be dispersed uniformly and finely.

Instead of the coarse-grained aluminum oxide powder added to the premixed powder, the surface of the coarse-grained aluminum oxide powder is provided with carbides, nitrides, and elements of the periodic table 4a, 5a, and 6a elements.
When a coated coarse-grain aluminum oxide powder coated with at least one selected from oxides, borides, and mutual solid solutions thereof is used, the diffusion of aluminum oxide into the matrix is delayed during sintering, resulting in a low Z value β. '-Sialon substrate and high Z value β
It is preferable because the Z value difference with the ′ -sialon lump is increased.

The coated coarse-grain aluminum oxide powder is CVD
Although it can be manufactured by a method, a PVD method, a solution coating method, etc., it can be easily and effectively performed by using the following method. Specifically, an aqueous solution of titanium sulfate, zirconyl nitrate or the like is added to aluminum oxide powder having an average particle size of about 3 to 20 μm and dried. Since these dense and strong oxide films are formed on the particle surfaces, uniform diffusion of aluminum oxide is prevented during sintering, resulting in a low Z value β'-
High Z value β'-sialon lumps can be uniformly and finely dispersed in the sialon matrix.

[0026]

Example 1 First, average particle diameters of 3.0 μm and 10 μm
To each Al ₂ O ₃ powder (each with M and C added) of
20% aqueous solution of rO (NO ₃ ) ₂ .2H ₂ O (denoted by Z) and 24% aqueous solution of Ti (SO ₄ ) ₂ (denoted by T)
Was added to the composition shown in Table 1 and dried at 120 ° C.,
Put in an alumina crucible and put in an atmospheric furnace at 1000 ℃ × 30
Heat treatment for minutes was performed. Table 1 shows the identification results of the obtained treated powder by X-ray diffraction and the compositions obtained by calculation. When the treated powder was observed with a scanning electron microscope,
The surface of the particles was covered with a uniform thin film.

[0027]

[Table 1]

Next, α-Si having an average particle diameter of 0.5 μm
₃ N ₄ (α crystallization rate 95%, oxygen content 1.5%), 0.2μ
Al ₂ O ₃ (denoted by F), 0.9 μm AlN,
1.0 μm TiN, 0.2 μm ZrO ₂ , 0.8 μm
m Y ₂ O ₃ and 1.2 μm Dy ₂ O ₃ powder,
Compounded in the composition shown in Table 2, the solvent of ethyl alcohol,
Wet mixing was performed for 48 hours using a urethane-lined pot and an alumina crushing ball, and then dried to obtain mixed powders a to j. The mixed powder of c and f was filled in a mold to form a molded body at a pressure of 98 MPa, put in an alumina crucible, subjected to heat treatment in nitrogen at 1200 ° C. for 60 minutes, and then pulverized in a mortar, 600 # ~ 32 using a sieve
The granulated powder was 5 # (G is added).

[0029]

[Table 2]

Lastly, the mixed powders a to h, the granulated powders c (G) and f (G), and the coated Al ₂ O ₃ powders MAZ, MAT, CAZ and CAT are used. 3 was mixed in the composition shown in Fig. 3 with a solvent of ethyl alcohol, a pot lined with urethane, and a ball for grinding made of alumina for 2 hours, and then 5% by weight of paraffin wax was added while drying. . Then, the mold is filled, and the pressure is about 5.5 × 17 × 43 at a pressure of 196 MPa.
mm powder compacts were produced. This was placed on a boron nitride setter and heated in a vacuum of about 50 Pa to 40
After holding at 0 ° C for 60 minutes to scatter the paraffin wax, the temperature was raised to 1200 ° C. And 0.5 MPa
Nitrogen gas is introduced and heated further, and it is heated at 1650 ° C. for 12 hours.
By holding for 0 minutes, the sintered bodies of the present invention products 1 to 10 and the comparative products 1 to 6 were obtained. All the ceramics sintered bodies were subjected to HIP treatment at 1700 ° C. for 60 minutes in nitrogen of 150 MPa after sintering.

[0031]

[Table 3]

The ceramics sintered body thus obtained was cut into a square rod shape with a diamond cutter, and wet-ground with a # 600 diamond grindstone to obtain 3.0 × 4.0 × 35.0.
After making a JIS test piece of mm, the bending strength was measured. The results are shown in Table 4. In addition, one surface of the sample is 0.3μ
After lapping with a diamond paste of m, the hardness and fracture toughness value K1C (IM method) at a load of 19.6 N using a Vickers indenter were measured, and the results are also shown in Table 4.

[0033]

[Table 4]

Furthermore, regarding the lapping surface of each sample,
The β'-sialon diffraction peak was taken using an X-ray diffractometer, and the Z value was calculated from the lattice constant by a conversion formula. here,
The lattice constant of β'-sialon is (110) plane, (10
It was determined from the peak positions in the X-ray diffraction patterns of the (1) plane and the (201) plane using the least-squares approximation method. The obtained Z value and peak intensity ratio are shown in Table 4. Further, a composition image of Al was taken using a scanning analytical electron microscope, and the average diameter of a region having a large amount of Al (a speckled portion having a high Z value) was measured. The results are also shown in Table 4.

[0035]

[Example 2] Using the mixed powders of the present invention 1 to 10 and Comparatives 1 to 6 obtained in Example 1, SN described in the ISO standard
With a mold for GN120408 shape, SNGN120408 shape (0.1 × −25 °) was obtained by press molding, heat sintering and wet grinding under the same method and conditions as in Example 1.
Of the cutting tool) was produced.

Work Material: FC350, Cutting Speed:
500 m / min, depth of cut: 1.5 mm, feed: 0.3
A wet outer peripheral continuous turning test was performed under the condition of mm / rev, and the time until the end of life was obtained. As the evaluation of the life, the life was defined when the average flank wear amount (VB) was 0.3 mm or more, or when chipping or chipping occurred. The results are shown in Table 5.

Work Material: FCD600 (45 × 20
0 mm surface), cutting speed: 150 m / min, depth of cut:
1.5 mm, feed: 0.12 mm / rev to 0.03
A dry milling cutting test was performed under the condition of increasing in increments of mm, and the maximum feed amount when the chip was chipped or chipped was obtained. The results are also shown in Table 5.

Next, work material: Waspaloy, cutting speed: 1
25 m / min, depth of cut: 1.0 mm, feed: 0.15
mm / rev, cutting time: Wet outer circumference continuous turning test was performed under the conditions of 3 min, and the average flank wear amount and boundary wear amount were measured. The results are also shown in Table 5.

[0039]

[Table 5]

From the results of the cutting test shown in Table 5, comparing the product of the present invention and the comparative product with chips having almost the same composition, the product of the present invention was
FC350 turning test life is about twice as long, FCD600 milling test is improved by 1-2 ranks, and boundary wear amount is about 1/2 in Waspaloy turning test.
It can be said that the combination of ′ -sialon particles improves the cutting performance.

[0041]

As described above, in the β'-sialon-based ceramic tool of the present invention, β'-sialon particles having a small Z value act to improve strength and toughness, and β'-sialon particles having a large Z value. Has an effect of improving hardness, and by these effects, when the β'-sialon-based ceramics tool of the present invention is used as a cutting tool, it has an effect of improving wear resistance, chipping resistance, and chipping resistance. It is something to demonstrate. As a method for producing the product of the present invention, β having a large Z value is obtained by adding coarse aluminum oxide powder to β′-sialon mixed powder having a small Z value and sintering the mixture.
′ -Cialon crystalline particles are produced.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 3C046 FF33 FF37                 4G001 BA03 BA32 BA36 BA37 BA38                       BA39 BB52 BC02 BC11 BC13                       BC52 BC54 BD18 BE03

Claims (9)

[Claims] 1. In a β'-sialon-based ceramic tool, β'-sialon (Si _6-Z Al _Z 0 _Z N _8-Z ) is
A β'-sialon-based ceramic tool containing a low Z-value β'-sialon with 0.03 ≤ Z <1.0 and a high Z-value β'-sialon with 1.1 ≤ Z <4.0. 2. A β'-sialon-based ceramic tool, comprising the β'-sialon (110) plane and (101) face.
X-ray diffraction pattern on at least one plane selected from the plane and the (201) plane is a β'-sialon-based ceramics tool having two peaks. 3. The weight ratio of the low Z value β′-sialon to the high Z value β′-sialon is such that the low Z value β′-sialon: high Z value β′-sialon = 20: 80 to 80:20.
The β'-sialon-based ceramics tool according to claim 1, wherein 4. The β'-sialon-based ceramic tool comprises a grain boundary phase of 1 to 10% by weight and a dispersed phase of 0 to 30% by weight.
The β'-sialon-based ceramics tool according to any one of claims 1 to 3, wherein the balance comprises the β'-sialon and inevitable impurities. 5. The β'-sialon-based ceramic tool according to claim 4, wherein the grain boundary phase is composed of at least one kind of rare earth oxide. 6. The dispersed phase is zirconium oxide, nitride, oxynitride, titanium carbide, nitride, carbonitride,
The β'-sialon according to claim 4 or 5, comprising at least one of hafnium nitride, tungsten carbide, tantalum carbide, nitride, carbonitride, niobium carbide, nitride and carbonitride. Basic ceramics tool. 7. The β'-sialon-based ceramics tool has a low Z value β'-sialon matrix with an average diameter of 5 to 100.
A high Z value β′-sialon lump having a particle size of μm is present, and the low Z value β′-sialon matrix is 1 to 10 wt% of the grain boundary phase.
And 0 to 30% by weight of the dispersed phase and the rest of the low Z value β'-
Sialon, wherein the high Z-value β'-sialon agglomerate comprises 1 to 10% by weight of the grain boundary phase, 0 to 30% by weight of the dispersed phase, and the balance of the high Z-value β'-sialon. The β'-sialon-based ceramics tool according to any one of 6 above. 8. A method for producing a β'-sialon-based ceramics tool comprising a powder mixing step and a sintering step, wherein silicon nitride, aluminum nitride, an oxide of a rare earth, and optionally finely divided aluminum oxide, periodic table 4a. , 5a, 6a
Powder mixing step 1 for obtaining a premixed powder by mixing at least one selected from the group consisting of carbides, nitrides, oxides, borides, and mutual solid solutions thereof, and an average particle of the premixed powder A powder mixing step 2 in which a coarse-grained aluminum oxide powder having an average particle diameter that is at least twice the diameter is mixed
And a sintering step of sintering at a temperature of 1400 to 2000 ° C in a nitrogen atmosphere, and a method for producing a β'-sialon-based ceramics tool. 9. A method for producing a β'-sialon-based ceramics tool comprising a powder mixing step and a sintering step, wherein silicon nitride, aluminum nitride, a rare earth oxide, fine aluminum oxide if necessary, and Periodic Table 4a. , 5a, 6a
Powder mixing step 1 for obtaining a premixed powder by mixing at least one selected from carbides, nitrides, oxides, borides of group elements, and mutual solid solutions thereof, and an average particle of the premixed powder On the surface of the coarse-grained aluminum oxide powder having an average particle size more than twice the diameter,
Powder mixing step 2 of mixing coated coarse-grained aluminum oxide powder coated with one or more selected from the group consisting of carbides, nitrides, oxides, borides of 6a group elements, and mutual solid solutions thereof, and in a nitrogen atmosphere And a sintering step of sintering at a temperature of 1400 to 2000 ° C. for manufacturing a β′-sialon-based ceramics tool.