KR102086569B1 - Method for manufacturing sialon-based ceramic materials for cutting tools having enhanced toughness and materials manufactured thereby - Google Patents

Abstract

The present invention relates to a method for producing a sialon ceramic material for cutting tools having improved toughness and a material produced by the same, more specifically, (a) preparing at least three kinds of ceramic raw material powders; (b) mixing and granulating the three or more ceramic raw powders; (c) preparing and degreasing the molded body by uniaxial pressure molding the mixed powder obtained in step (b); And (d) manufacturing the dense material by gas pressure reaction sintering of the degreasing molded body obtained in the step (c), to a method for producing a sialon ceramic material for cutting tools having improved toughness and to the material produced thereby. It is about. According to the present invention, by using gaseous reaction sintering as a sintering means by using silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), alumina (Al ₂ O ₃ ), and iterbia (Yb ₂ O ₃ ) as raw materials, Since it is possible to manufacture a sialon ceramic material having as much as 100% by weight of β-sialon and reducing pores as much as possible, it is possible to provide a sialon ceramic material for cutting tools with improved cutting performance by improving fracture toughness.

Description

METHOD FOR MANUFACTURING SIALON-BASED CERAMIC MATERIALS FOR CUTTING TOOLS HAVING ENHANCED TOUGHNESS AND MATERIALS MANUFACTURED THEREBY}

The present invention relates to a method for producing a sialon ceramic material used as a cutting tool and a material produced thereby.

With the development of gas turbine-related industries, the demand for the development of cutting tools for cutting metal materials used in related parts is increasing.

Ti-group and Ni-based metals are mainly used for metal parts of aviation / power generation gas turbines. Especially, Ni-based Heat Resistant Super-Alloy (HRSA), which is applied to high temperature parts, has high melting point, high hardness, and high temperature corrosion resistance. It is widely used as a high-temperature structural material due to its excellent properties. Heat-resistant superalloys are classified as difficult materials to be cut compared to general metal materials due to their physical properties such as high hardness and low thermal conductivity. Cutting tools of various materials, such as ceramics and cBN, are used industrially, and typical ceramic materials include sialon (SiAlON) and alumina whisker (Al ₂ O ₃ -SiC _w ) composites.

Sialone is a ceramic material developed by solidifying oxides such as alumina as a sintering aid for the sintering of β-silicon nitride (Si ₃ N ₄ ) in the solid phase between oxide and nitride of Si-Al-ON system. The substitution of Al-O bonds for Si-N bonds of β-silicon nitride is known as β-sialon and is represented by the general formula Si _6-z Al _z O _z N _8-z and α-sialon is Me-Si- Another phase of sialon stabilized with metal Me ions in the Al-ON system is known as Me, and rare earth (RE, Rare-Earth) ions such as Li, Mg, Ca and Y, Yb, and Sm. The sialon is expressed as Me _m Si _{12- (pm + n)} Al _{pm + n} O _n N _16-n when stabilized with Me ^{p +} ions.

In the case of sialon ceramics, nitrides such as silicon nitride and aluminum nitride and sintering aids are mixed with oxides of silica, alumina and rare earth oxides to densify through transient liquid sintering, and are reactive gas-pressure sintering. One of the representative densification methods, β-sialon, α-sialon, and inter-granular phases (IGP) exist in the microstructure of sialon ceramics densified through reaction sintering. The proportions of amorphous and crystalline phases in the IGP, etc., are known to determine the mechanical, chemical and thermal properties of sialon ceramics.

For example, mechanical properties such as hardness, bending strength, and fracture toughness of the ceramic materials used as cutting tools are known to determine cutting performance. In the case of sialon ceramics, anisotropic growth of specimens occurs in the sintered body. β-sialon particles have fracture toughness of the material, and α-sialon, which contains metal ions other than silicon and aluminum in the crystal structure, is closely related to hardness and the composition ratio of inter-granular phases (IGP) It is known that the lower the ratio of the crystal phase in the grain boundary phase, the better the mechanical properties of the sialon.

Therefore, in the sialon ceramics used as cutting tools, a compact sintered body is obtained through gas pressure reaction sintering, and the cutting ratio is improved by optimizing the hardness and fracture toughness of the material by adjusting the ratio of β-sialon and α-sialon. There is an increasing need for techniques that can be improved.

 E. O. Ezugwu, Inter. J. Mach. Tools & Manufac. 45 (2005) 1353.  I.-W. Chen, A. Rosenflanz, Nature 389 (1997) 701.  A. Rosenflanz, I.-W. Chen, J. Euro. Ceram. Soc. 19 (1999) 2325.  A. Rosenflanz, Curr. Opin. Solid State Mater. Sci. 4 (1999) 453.  V. Izhevskiy, L. Genova, J. Bressiani, F. Aldinger, J. Eur. Ceram. Soc. 20 (2000) 2275.  H. Mandal, J. Euro. Ceram. Soc. 19 (1999) 2349.  W.D. Kingery, Y. Chiang, D. Birnie, Physical. Ceramics: Principles for Ceramic Science and Engineering (1997).  B. Bitterlich, S. Bitsch, K. Friederich, J. Euro. Ceram. Soc. 28 (2008) 989.  N. Calis Acikbas, O. Demir, Ceram. Inter. 39 (2013) 3249.

The technical problem to be solved by the present invention is to adjust the normal ratio of β-sialon and α-sialon in the sialon ceramic material densified by press molding and degreasing the mixture of nitride, oxide and rare earth oxide and reacting gas pressure sintering. In particular, the present invention provides a method for manufacturing a sialon ceramic material for a cutting tool capable of improving cutting performance by improving fracture toughness by having a β-sialon phase mainly.

In order to achieve the above technical problem, the present invention comprises the steps of (a) preparing three or more kinds of ceramic raw material powder; (b) mixing and granulating the three or more ceramic raw powders; (c) preparing and degreasing the molded body by uniaxial pressure molding the mixed powder obtained in step (b); And (d) producing a dense material by gas pressure reaction sintering of the degreasing body obtained in step (c).

In addition, aluminum having an Al _eq of more than 0.14 and less than 0.23 according to formula (1), yb _eq of more than 0.006 and less than 0.016 according to formula (2) below, and an O _eq of more than 0.08 and less than 0.12 according to formula (3) below. A method for producing a sialon ceramic material for cutting tools with improved toughness, characterized in that Si-Al-Yb-ON based sialon is prepared from a ceramic raw material powder containing oxygen:

(1)

(One)

(2)

(2)

(3)

(3)

Wherein Al _at , Yb _at , Si _at , O _at, and N _at are the atomic fractions of aluminum, ytterbium, silicon, oxygen, and nitrogen present in all the ceramic raw materials prepared in step (a), respectively. Al _eq , Yb _eq and O _eq are equivalent ratios of aluminum, ytterbium, and oxygen, respectively.

In addition, in step (a), silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), alumina (Al ₂ O ₃ ) and Ytterbia (Yb ₂ O ₃ ) powder having improved toughness, characterized in that to prepare A method for producing a sialon ceramic material for cutting tools is proposed.

Further, in step (a) 66.7 to 79.0% by weight of Si ₃ N ₄ , 7.3 to 12.5% by weight of AlN, 10.3 to 14.9% by weight of Al ₂ O ₃ and 3.4 to 7.6% by weight of Yb ₂ O ₃ powder We propose a method for producing a sialon ceramic material for cutting tools having improved toughness, characterized in that the preparation.

In addition, the step (b) is a sialon ceramic material for cutting tools having improved toughness, characterized in that performed by ball milling (ball milling), planetary ball milling (planetary milling) or attrition milling (attrition milling) We propose a method of manufacturing.

In addition, the granulation of the powder mixed in the step (b) is a method for producing a sialon ceramic material for cutting tools having improved toughness, characterized in that is carried out by spray drying or freeze drying. Suggest.

In addition, the method of manufacturing a sialon ceramic material for cutting tools having improved toughness, characterized in that the step (c) is carried out by uniaxial pressing and cold isostatic press (CIP). Suggest.

In addition, the forming of the sialon ceramic material for cutting tools having improved toughness, characterized in that the molding in step (c) is carried out by uniaxial pressing and cold isostatic press (CIP). Suggest a method.

In addition, after performing step (c) and before performing gas pressure sintering of step (d), the improved toughness characterized in that the degreasing is maintained at a temperature of 300 to 500 ° C. for 0.5 to 1.5 hours in a vacuum or oxidizing atmosphere. The eggplant proposes a method for producing a sialon ceramic material for cutting tools.

In addition, the gas pressure reaction sintering of step (d) is carried out by vacuum sintering, hot press, gas pressure sintering or hot isostatic press (HIP). We propose a method for producing a sialon ceramic material for cutting tools having improved toughness.

In addition, the step (d) of the sialon ceramic material for cutting tools having improved toughness, characterized in that carried out for 1 to 6 hours at a temperature of 1700 ℃ to 1900 ℃ and nitrogen or argon gas pressure of 0.1 to 15 MPa We propose a manufacturing method.

In addition, the present invention proposes a sialon ceramic material for a cutting tool having improved toughness produced by the manufacturing method.

In addition, the present invention proposes a sialon ceramic material for cutting tools having improved toughness, characterized in that the porosity is 2% or less.

Also, (i) consisting of β-sialon, or (ii) at least 80% by weight of β-sialon and greater than 0% by weight of 20% by weight of α-sialon A sialon ceramic material for cutting tools having toughness is proposed.

According to the method for producing a sialon ceramic material for cutting tools having improved toughness according to the present invention, β-Si in the sialon ceramic material densified by press forming and degreasing a mixture of nitride, oxide and rare earth oxide and reacting gas by pressure sintering It is possible to produce a sialon ceramic material for cutting tools in which the ratio of allons and α-sialons is adjusted, and in particular, the β-sialon phase is mainly contained to improve cutting performance by improving fracture toughness.

1 is a flowchart of a method of manufacturing a sialon ceramic material according to the present invention.
FIG. 2 illustrates a phase region of β-sialon and α-sialon in a Si-Al-ON-RE system or a Si ₃ N ₄ -SiO ₂ -AlN-Al ₂ O ₃ -REN-RE ₂ O ₃ composition system It is a schematic diagram of Jaenecke prism.
Figure 3 is a graph showing the equivalent ratio of aluminum, ytterbium, and oxygen of the composition used in Examples 1 to 4 and Comparative Example 1 of the present application.
4 is an X-ray diffraction (XRD) analysis of the sialon ceramic material prepared in Examples 1 to 4 and Comparative Example 1 of the present application.
5 (a) is an example of X-ray diffraction peaks used to calculate the relative weight ratios of β-sialon and α-sialon in the X-ray diffraction (XRD) analysis.
FIG. 5 (b) shows the relative weight ratios of β-sialon and α-sialon in the X-ray diffraction (XRD) analysis results for the sialon ceramic materials prepared in Examples 1 to 4 and Comparative Example 1 of the present application. The result is.
6 is a scanning electron microscope (SEM) photograph showing the microstructure of the sialon ceramic material prepared in Examples 1 to 4 and Comparative Example 1 of the present application.
7 is a Rockwell hardness measurement results of the sialon ceramic material prepared in Examples 1 to 3 and Comparative Example 1 of the present application.
8 is a measurement result of room temperature bending strength of the sialon ceramic material prepared in Example 3 and Comparative Example 1 of the present application.
9 is a fracture toughness measurement results of the sialon ceramic material prepared in Example 3 and Comparative Example 1 of the present application.

In the following description of the present invention, if it is determined that detailed descriptions of related known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Embodiments according to the concepts of the present invention may be variously modified and may have various forms, and specific embodiments will be illustrated in the drawings and described in detail in the present specification or application. However, this is not intended to limit the embodiments in accordance with the concept of the present invention to a particular disclosed form, it should be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. As used herein, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof that is described, and that one or more other features or numbers are present. It should be understood that it does not exclude in advance the possibility of the presence or addition of steps, actions, components, parts or combinations thereof.

Hereinafter, the present invention will be described in detail.

1 is a flow chart showing a manufacturing method of a sialon ceramic material for cutting tools having improved toughness according to the present invention, as shown in Figure 1 is a manufacturing method according to the present invention (a) Preparing; (b) mixing and granulating the three or more ceramic raw powders; (c) preparing and degreasing the molded body by uniaxial pressure molding the mixed powder obtained in step (b); And (d) preparing the dense material by gas pressure reaction sintering of the degreasing body obtained in step (c), which will be described in detail below.

The three or more kinds of ceramic raw material powders prepared in step (a) vary in kind depending on the composition of the sialon ceramic material for the cutting tool finally produced. For example, the composition of sialon can be explained by a multidimensional state diagram and one method of displaying this multidimensional state diagram for a Si-Al-ON-RE system is the Jaenecke prism as illustrated in FIG. In the sialon ceramic material for cutting tools according to the present invention, the following equations defined by the calculated composition of the raw material are used:

(1)

(One)

(4)

(4)

(3)

(3)

The subscripts "at" and "eq" refer to the atomic ratio and equivalent ratio of elements present in all raw materials of nitrides and oxides used in the preparation of sialon.

In addition, the three or more types of ceramic raw material powders prepared in step (a) may be silicon nitride (Si ₃ N ₄ ), nitrided when producing a sialon ceramic material for cutting tools having β-sialon and α-sialon. At least one of oxides of lanthanum rare earth elements such as yttria (Y ₂ O ₃ ), ytterbia (Yb ₂ O ₃ ), samaria (Sm ₂ O ₃ ), besides aluminum (AlN) and alumina (Al ₂ O ₃ ) You can prepare together.

Step (b) is a step of mixing, drying and granulating the three or more ceramic raw material powders prepared in the previous step, wherein the method of forming the mixed powder in this step only allows the raw material ingredients to be uniformly mixed to form a composition. The specific method is not particularly limited. Preferably, the method is mechanically mixed through milling using a ball mill, a planetary mill, an attrition mill, or the like. Steps may be performed.

It is preferable to use anhydrous ethanol or toluene as a solvent used to prevent oxidation of the nitride powder used as a raw material in the mixing process shown in step (b). In order to maintain the viscosity and strength of the granules to form the granules, it is preferable to add a dispersing agent such as triethylamine, NH ₄ OH and a binder such as polyethyleneglycol (PEG). The specific method is not particularly limited, and this step may be preferably performed through a mixed powder granulation process having flowability using spray drying, freeze drying, or the like.

Step (c) is to prepare the molded specimen by pressing using the mixed powder obtained in the previous step, in this step, press forming such as uniaxial pressing and cold isostatic press (CIP) Molding can be carried out using.

If necessary, after performing step (c) and before carrying out the gas pressure sintering of step (d), which will be described later, a vacuum is used to degrease impurities such as organic substances that may be included in the ceramic formed body obtained in step (c). Or debinding in an oxidizing atmosphere. At this time, the degreasing is preferably carried out at a temperature and time enough to completely remove the organic matter, for example, it can be carried out by maintaining for 0.5 to 1.5 hours at a temperature of 300 to 500 ℃.

In step (d), a dense material is prepared by gas pressure reaction sintering using the degreasing molded body obtained in the previous step, and in this step, vacuum sintering, hot press, gas pressure sintering or Gas pressure reaction sintering, such as hot isostatic press (HIP), can be used to simultaneously form and denaturate sialon from the raw material mixture.

In the gas pressure reaction sintering step, the sintering conditions such as the sintering temperature, pressure and sintering time are determined by the type and content of the raw ceramic powder and finally between β-sialon and α- of the sialon ceramic material for cutting tools. It may be appropriately selected in consideration of the ratio of alon and control of microstructure.

For example, in addition to silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), alumina (Al ₂ O ₃ ), yttria (Y ₂ O ₃ ), ytterbia (Yb ₂ O ₃ ), and samaria (Sm ₂ O ₃₎ When the specimen is prepared using at least one of lanthanum-based rare earth element oxides, etc.), this step is performed for 1 to 6 hours at a temperature of 1700 ° C to 1900 ° C and a nitrogen or argon gas pressure of 0.1 to 15 MPa. It is preferable to carry out.

At this time, if the sintering temperature is less than 1700 ° C sintering is not achieved sufficiently, if the sintering temperature exceeds 1900 ° C problem occurs that the economic deterioration due to the high sintering temperature. In addition, when the sintering time is less than 1 hour, sufficient sintering is difficult to be achieved. When the sintering time is more than 6 hours, it is not preferable in view of the cost of the manufacturing process.

Regarding the sintering temperature, after determining the arbitrary temperature T1 and T2 (wherein T1 <T2) belonging to the selected sintering temperature range in consideration of the type and content of the raw ceramic powder as described above, and then during the sintering time from T1 to T2 It may be performed while gradually increasing, or may be performed while maintaining the sintering time at a predetermined temperature in the sintering temperature range. When sintering at a predetermined temperature, it may be maintained at only one temperature level, or may be maintained at a plurality of temperature levels. In this case, when maintaining at a plurality of temperature levels, the holding time at each temperature level is the same or different. can do.

Regarding the gas pressure during sintering, after determining the arbitrary pressures P1 and P2 (where P1 <P2) belonging to the selected sintering gas pressure range in consideration of the type and content of the raw ceramic powder as described above, T1 to T2 It may be performed while gradually pressurizing during the sintering time, or may be performed while maintaining the sintering time at a predetermined gas pressure belonging to the sintering gas pressure range. When sintering at a predetermined gas pressure, it may be maintained at only one gas pressure level, or may be maintained at a plurality of gas pressure levels. In this case, when maintaining at a plurality of gas pressure levels, it is maintained at each gas pressure level. The time can be the same or different.

On the other hand, the gas pressure reaction sintering of this step is preferably performed in a nitrogen atmosphere or an inert atmosphere to prevent denitrification from the nitride raw material.

The specimen produced by the method for producing a sialon ceramic material for cutting tools having improved toughness according to the present invention described above in detail is made of β- or α-sialon ceramics.

For example, in addition to silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), alumina (Al ₂ O ₃ ), yttria (Y ₂ O ₃ ), yttervia (Yb ₂ O ₃ ), and / or samaria ( When the ceramic material is manufactured using Sm ₂ O ₃ ) as a raw material powder, the sialon ceramic material may be β-sialon ceramics represented by the following Chemical Formula 1, α-sialon ceramics represented by the following Chemical Formula 2, and grain boundary phase (IGP). It may consist of a complex consisting of).

[Formula 1]

Si _6-z Al _z O _z N _8-z ,

[Formula 2]

RE _{m / 3} Si _{12- (m + n)} Al _{m + n} O _n N _16-n

Wherein RE is Y, Yb, or Sm

For reference, in the case of β-sialon represented by the formula of Si _6-z Al _z O _z N _8-z , as shown in Formula 1, as shown in FIG. 2, silicon nitride of the Janet prism (Si ₃ N ₄₎ Si ₃ N ₄ -SiO ₂ -AlN-Al ₂ O _3, which is present on the compositional surface, is represented by RE _{m / 3} Si _{12- (m + n)} Al _{m + n} O _n N _{16- In} the case of α-sialon represented by the chemical formula of _n , it is represented by a point in the Janek prism, and the general formula of the sialon raw material composition is expressed as the equivalent of each element described above and at the same time RE _{m / 3} Si _{12- (m + n )} Al _{m + n} O _n N It is also expressed in the form of _16-n .

Furthermore, the mechanical properties such as hardness, bending strength and fracture toughness of the sialon ceramic materials for cutting tools are known to determine the cutting performance, and β-sialon particles in which anisotropic growth of specimens in the sintered compact are produced. The fracture toughness of and the α-sialon, which contains metal ions other than silicon and aluminum in the crystal structure, are closely related to hardness, and the lower the composition ratio of intergranular phases (IGP) is, The larger the ratio, the better the sialon mechanical properties can be expected.

In particular, the material produced by the method of manufacturing a sialon ceramic material for cutting tools having improved toughness according to the present invention described above in detail, the porosity (porosity) of 2% or less in the state of the pore interference is maximally excluded When the cutting tool is applied, the pores present in the material are minimized to cause the breakdown, and the ratio of β-sialon and α-sialon is adjusted, and in particular, the β-sialon phase is mainly used to improve fracture toughness. As a result, a sialon ceramic material for cutting tools with improved cutting performance can be provided.

Hereinafter, the present invention will be described in detail with reference to Examples. However, embodiments according to the present disclosure may be modified in various other forms, and the scope of the present specification is not interpreted to be limited to the embodiments described below. The embodiments of the present specification are provided to more fully describe the present specification to those skilled in the art.

<Examples 1 to 4 and Comparative Example 1>

1. Manufacturing of sialon ceramic materials for cutting tools

The composition of Examples 1 to 4 and Comparative Example 1 according to the present invention is selected by changing the addition amount of Yb ₂ O ₃ used as a sintering aid and the Si / Al ratio or O / N ratio of the raw material composition Si ₃ N ₄ to have a composition of Yb _{m / 3} Si _{12- (m + n)} Al _{m + n} O _n N _16-n (m = 0.3 / 0.7, n = 1.9, 2.3, 2.7) as shown in FIG. (SN-E10, UBE Ind., Japan, 0.5 μm), Yb ₂ O ₃ (YBO01PB, Kojundo Chemical Laboratory Co., Ltd., Japan, purity: 99.9% (3N)), AlN (H grade, Tokuyama, Japan, 1.07 ~ 1.17 μm), Al ₂ O ₃ (AES-11, Sumitomo Co., Japan, 0.5 μm) was used as a raw material and weighed according to the composition of Table 2.

Schematic diagrams of Al _eq , Yb _eq , and O _eq in the compositions of Examples 1 to 4 and Comparative Example 1 shown in Table 1 are shown in FIG. 3 as x, y, z axes as Al _eq , Yb _eq , and O _eq , respectively. .

2 vol% and 4 wt% of NH ₄ OH and triethylamine were added to the weighed powder mixture, 4 wt% of PEG # 4000 was used as an organic binder, and 4 wt% of non-aqueous anhydrous ethanol (Anhydrous) was used as the solvent. ethanol, Daejung Chem. & Metals, Korea, purity: 99.9%) using a 10 mm diameter alumina ball was ball milled for 24 hours.

A spray drying process (Mini spray dryer, B-290, BUCHI, Switzerland) was used to dry the sample, increase the molding density and improve the sintered density. The atomizing gas was used to prevent the oxidation of nitride. In order to use high-purity nitrogen gas, the flow rate was 40 mL / min, and the slurry injection rate was 9 mL / min, followed by drying and powder granulation.

Molded specimens were prepared by uniaxial pressure molding at a molding pressure of 1.3 tonf / cm ² and degreased at 450 ° C. for 30 minutes to remove the organic binder. Densification was sintered using a gas pressure sintering (GPS) at a rate of 5 ° C. per minute in an N ₂ pressurized atmosphere at 10 atm and maintained at a sintering temperature of 1820 ° C. for 90 minutes.

<Experimental Example 1> Crystal structure and microstructure analysis of the sialon ceramic material for cutting tools prepared in Examples 1 to 4 and Comparative Example 1

X-ray diffraction (XRD) analysis was performed on the sialon ceramic materials prepared in Examples 1 to 4 and Comparative Example 1 of the present application, and the results are shown in FIG. 4.

It was shown from FIG. 4 that the densified sialon ceramic material is mainly composed of β-sialon and α-sialon, and in particular, in the case of the sialon ceramic material prepared in Examples 1 to 3, X from β-sialon -Ray diffraction peaks were mainly seen.

FIG. 5 (a) shows two peaks for analyzing the weight ratio of β-sialon and α-sialon of the sialon ceramic material prepared according to the present invention from X-ray diffraction peaks. From the intensities I _β and I _α of the two diffraction peaks, the phase ratio of β- / α-sialon can be obtained by the following equation.

(5)

(5)

Where w _β is the weight ratio of β-sialon and K is the proportional constant calculated from the following two equations.

(6)

(6)

(7)

(7)

Where K is 0.518 when the two peaks of FIG. 5 (a) are used.

FIG. 5 (b) shows the weight ratio of β-sialon and α-sialon of the sialon ceramic materials prepared in Examples 1 to 4 and Comparative Example 1 from the intensity of the X-ray diffraction peaks as described above. Calculated graph

It can be seen from FIG. 5 (b) that the sialon ceramic material for cutting tools having improved toughness according to the present application is composed of 80.8 to 100 wt% of β-sialon and 0 to 19.2 wt% of α-sialon.

Fig. 6 is a cross-sectional fine line showing β-sialon (β), α-sialon (α) and grain boundary phase (IGP) of the sialon ceramics prepared in Examples 1 to 4 and Comparative Example 1 of the present application. Scanning electron microscope (SEM) images showing the structure.

<Experimental Example 2> Mechanical property analysis of the sialon ceramic material for cutting tools prepared in Examples 1 to 4 and Comparative Example 1

Rockwell hardness values for the sialon materials prepared in Examples 1 to 4 and Comparative Example 1 are shown in FIG. 7. The sialon material for cutting tools according to the present application showed a hardness value of 92.8 to 93.7 HRA.

Room temperature bending strength values for the sialon material prepared in Example 3 and Comparative Example 1 are shown in FIG. 8. The sialon material for cutting tools according to the present application showed a strength value of 627 MPa.

The fracture toughness values for the sialon material prepared in Example 3 and Comparative Example 1 are shown in FIG. 9. Between for the cutting tool according to the present sialon material showed a fracture toughness of 6.1 MPam ^1/2.

Claims (14)

(a) preparing 72.49 wt% Si ₃ N ₄ , 9.18 wt% AlN, 14.93 wt% Al ₂ O ₃ and 3.39 wt% Yb ₂ O ₃ powder as ceramic raw powder;
(b) mixing and granulating the ceramic raw material powder;
(c) preparing and degreasing the molded body by uniaxial pressure molding the mixed powder obtained in step (b); And
(D) A method for producing a sialon ceramic material for cutting tools having improved toughness comprising the step of producing a dense material by gas pressure reaction sintering the degreasing body obtained in step (c). delete delete delete The method of claim 1,
The step (b) is to produce a sialon ceramic material for cutting tools having improved toughness, characterized in that performed by ball milling (ball milling), planetary ball milling (planetary milling) or attrition milling (attrition milling) Way. The method of claim 1,
Granulation of the powder mixed in the step (b) is a method for producing a sialon ceramic material for cutting tools having improved toughness, characterized in that is carried out by spray drying or freeze drying. The method of claim 1,
Method of producing a sialon ceramic material for cutting tools having improved toughness, characterized in that the step (c) is performed by uniaxial pressing and cold isostatic press (CIP). delete The method of claim 1,
After performing step (c) and before carrying out the gas pressure sintering of step (d), the cutting having improved toughness, characterized in that the degreasing is maintained at a temperature of 300 to 500 ° C. for 0.5 to 1.5 hours in a vacuum or oxidizing atmosphere. Method for producing a sialon ceramic material for tools. The method of claim 1,
Gas pressure reaction sintering of step (d) is characterized in that it is carried out by vacuum sintering, hot press, gas pressure sintering or hot isostatic press (HIP) Method for producing sialon ceramic materials for cutting tools with improved toughness. The method of claim 1,
Step (d) is a method for producing a sialon ceramic material for cutting tools having improved toughness, characterized in that carried out for 1 to 6 hours at a temperature of 1700 ℃ to 1900 ℃ and nitrogen or argon gas pressure of 0.1 to 15 MPa. . A sialon ceramic material for cutting tools having improved toughness produced by the manufacturing method according to any one of claims 1, 5 to 7, and 9 to 11. The method of claim 12,
A sialon ceramic material for cutting tools with improved toughness, characterized in that the porosity is 2% or less. The method of claim 12,
A sialon ceramic material for cutting tools with improved toughness, characterized by consisting of β-sialon.

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