KR920004681B1 - Hard sintered compact for tools - Google Patents

Abstract

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Description

Sintered body for hard tool and manufacturing method

1 is a graph showing cutting test results in Example 4,

2 is a graph showing cutting test results in Example 6. FIG.

The present invention relates to an improved sintered compact for hard tools using cubic boron nitride (hereinafter abbreviated as CBN) and a method for producing the same.

Cubic boron nitride is a hard material next to diamond, and its sintered body is used in various cutting tools. An example of this kind of CBN sintered body suitable for cutting tools is described in Japanese Patent Laid-Open No. 77811/1978. In the prior art, carbides, nitrides, borides, silicides, or mixtures or interdissolved compounds of such transition metals selected from group IVa, Va, and VIa at periodic rates contain 80 to 40% by volume cubic boron nitride; A high hardness sintered body comprising Si and / or Al in an alloy is disclosed and the compound forms a continuous bonding phase during sintering operation. When the sintered compact for hard tools is used, carbides, nitrides, borides, silicides or these mutual solid solution compounds of transition metals selected from group IVa, Va and VIa of the periodic table are used, and these compounds are relatively hard and have a high melting point. Therefore, sintered bodies made of these compounds generally exhibit high performance as cutting tools.

When the sintered compact for high-precision tools disclosed in Japanese Patent Application Laid-Open No. 77811/1978 is used for a cutting tool, high performance is generally confirmed through the commercially available sintered compact.

However, when used as a cutting tool, there are the following problems depending on its use.

That is, when the CBN sintered body is used to intermittently cut hardened steel with key grooves or holes, stress acts on the blade tip of the CBN sintered body and breaks. The breakage of the blade tip is caused by the lack of strength of the blade tip and the crater wear that occurs on the rake surface of the tool and sharpens the blade tip.

In the above applications, the breakage of the blade tip means that the strength of the sintered compact for high hardness tool itself is insufficient and the crater resistance is poor.

Z

0.85이다), 함유되는 Ti와 IVa, Va, VIa족 전이금속과의 원자비가 2/1∼97/3이며, 텅스텐을 상기 Ti화합물 및 WC의 적어도 한쪽 형태로 함유하고, 전체 텅스텐농도가 4∼40중량%인 결합체를 혼합하고, CBN이 안정되는 고압상태하에서 혼합물을 소결하여 얻어진 소결체가 종래의 입벙정질화붕소 소결체보다 강도가 높고, 내마모성이 뛰어나다는 사실을 발견하였다.Accordingly, it is an object of the present invention to provide a sintered compact for high hardness tools which is much more excellent in strength and crater resistance than the above-mentioned conventional zirconia boron nitride sintered compact. In order to obtain the sintered compact, the present inventors have conducted 50 to 75% by volume of CBM; 20 to 50% by weight of Al, TiN _Z , Ti (C, N) _Z , TiC _Z , (TiM) C _Z , (Ti, M) (C, N) _Z and (Ti, M) N _Z Containing at least one Ti compound, wherein M is a IVa, Va, or VIa transition metal of the periodic table excluding Ti, Z being 0.5

Z

0.85), the atomic ratio of Ti to IVa, Va, and VIa transition metals contained is 2/1 to 97/3, and tungsten is contained in at least one form of the Ti compound and WC, and the total tungsten concentration is 4 to It was found that the sintered body obtained by mixing 40 wt% of the binder and sintering the mixture under high pressure with stable CBN has a higher strength and superior wear resistance than the conventional boron nitride sintered body.

In addition to CBM, the sintered compact according to the present invention is made of TiN, Ti (C, N), TiC, (Ti, M) C, (Ti, M) (C, N) or (Ti, M) N, titanium boride and aluminum bores. Carbohydrates, aluminum nitrides, tungsten compounds and / or tungsten are contained and form a continuous bonding phase in the tissue. According to the present invention, the high hardness CBN sintered body is obtained through a mixed powder containing 50 to 75 volume% of cubic boron nitride and the binder as the balance.

The content of CBM is selected from the following margins. When the CBM content is 50% by volume or less, the hardness of the sintered compact is lowered as described above, so that plastic flow occurs at the tip of the blade, leading to breakage. On the other hand, when the CBN content exceeds 75% by volume, the wear resistance is sharply lowered, crater wear increases, and the edge of the blade is sharpened and broken. In the case where the average size of the particles is 2 µm or more, the sintered compact containing CBN particles at 65% by volume or less decreases in strength and hardness. Therefore, when CBN particles having an average diameter of particles of 2 µm or more are used, the CBN content in the mixed powder should be about 65 to 75% by volume.

On the other hand, when the CBN particles having a size of 30 µm or more are used, the blade tip is broken by the chipping of the CBN particles themselves.

Therefore, it is not preferable to use CBN particles having a size of 30 µm or more.

On the other hand, when only CBN particles smaller than 2 µm are used, it is impossible to obtain a uniform sintered body by a mixed powder having a CBN particle content of more than 65% by volume. However, when the CBN particle size is 2 µm or less and preferably 1 µm or less, a uniformly structured high hardness sintered compact can be obtained when the mixed powder contains about 50 to 60% by volume of the CBN powder.

According to the invention, the binder is also mainly TiN _Z , Ti (C, N) _Z , TiO _Z , (Ti, M) C _Z , (TI, M) (C, N) _Z and (Ti, M) N _Z It consists of a component selected from.

Z

0.85이다). 즉, 사용된 물질은 Ti의 탄화물, 질화물 또는 탄질화물의 단체 또는 고용체이다. 이러한 물질은 유리 Ti를 함유하므로 CBN 및 Al화합물과 쉽게 반응하여 입방정 질화붕소를 결합상으로 견고히 결합시킨다.(Where M is a Periodic Table IVa, Va or VIa transition metal element excluding Ti and Z ranges from 0.5

Z

0.85). That is, the material used is a single or solid solution of carbide, nitride or carbonitride of Ti. Since these materials contain free Ti, they easily react with CBN and Al compounds to firmly bind cubic boron nitride to the bonding phase.

In addition, when carbides, nitrides, carbonitrides and their solid solutions containing Ti are expressed as described above, the value of Z is 0.5 " hZ " h0.85 for the following reason: if Z is less than 0.5 This is because the glass Ti decreases and the hardness of the sintered compact decreases, and when it exceeds 0.85, the bond strength of CBM and the binder decreases.

When carbides, nitrides, or carbonitrides of transition metals selected from Groups IVa, Va, and VIa of the periodic table are mixed with components of carbides, nitrides, and carbonitrides of Ti, the binder is improved in strength, and only the Ti compound is used as the binder. Compared with the improved performance.

Ti content in the binder requires that the atomic ratio of Ti to the metal element selected from IVa, Va and VIa of the periodic table is about 2/1 to 97/3. When the Ti content is less than 2/1, the bonding strength of the binder and CBN is reduced, while when the atomic ratio is more than 97/3, the binder decreases wear resistance and strength.

According to the invention, the binder also contains a significant amount of Al, on the order of approximately 20-50% by weight, which is Al in the binding phase TiN _Z , Ti (C, M) _Z , TiC _Z , (Ti, M) C _Z Enhance the bond strength between the bonded phase and CBN particles by reacting with (Ti, M) (C, M) _Z or (Ti, M) M _Z and CBN particles to produce compounds such as TiAl ₃ , AlN or AlB ₂ Because. When the Al content is less than 20% by weight of the binder, the crater resistance is reduced because the bond strength is reduced and the CBN particles easily fall off.

On the other hand, when Al content exceeds 50 weight%, content of CBN particle | grains is comparatively reduced and its intensity | strength falls, Therefore, a blade tip is easily broken. However, many preferred examples of the combination of Al content and Ti component content are as follows.

Firstly, the above-described Ti-containing component (TiC _Z , MC) _y- (MN) _1-y or (Ti, M) (Cy, N _1-y ), where M is the periodic table IVa, Va excluding Ti. And group VIa transition metal element, where y is 0.3 < y < 1.0, it is preferred to contain at least one such compound when the binder contains about 25-50% by weight of Al.

0.3의 범위내에 있는 것이 바람직하다.Secondly, when the binder contains approximately 20-30% by weight of Al, the y value in the above formula is 0 < y

It is preferable to exist in the range of 0.3.

According to the present invention, the binder also contains about 4 to 40% by weight of tungsten. Such tungsten improves wear resistance, but it does not improve when the turnsten content is less than 4% by weight of the binder. On the other hand, when the content of tungsten exceeds 40% by weight, the content of the Ti compound is reduced, thereby decreasing the bonding strength of the CBN and the binder. In particular, when W is used in M of the above formula, the binder is much more improved in wear resistance and strength, and thus a high quality hard sintered body can be obtained.

In the sintered compact according to the present invention, the binder phase of the binder described above is continuous in the structure, and it is entirely homogenized. When CBN particles of different sizes are combined in the CBN powder, fine CBN particles are filled between or around the coarse CBN particles, thereby increasing the CBN content, and as a result, the sintered body is improved in strength and wear resistance.

In order to produce the sintered body by the present invention, 50 to 75% by volume of the CBN powder and 25 to 50% by volume of the binder are mixed so that the CBN is sintered under stable high temperature and high pressure. TiH _Z , Ti (C, N) _Z , TiC _Z , (Ti, m) _Z , (Ti, M) (C, N) _Z or (Ti, M) N _Z or added in the form of an intermetallic compound Free Ti or free Al present in Al reacts with CBN to produce nitrides or rods of Ti or Al through the sintering to improve the bonding strength of CBN and binder.

Tungsten can be mixed into the binder in the form of pure tungsten, tungsten boride or tungsten carbide (WC), and Al is likewise mixed in the form of an Al compound. For cubic boron nitride used as a raw material, many different sizes of CBN particles may be mixed as described above, whereas only particles smaller than 2 μm in particle diameter, preferably less than 1 μm in average diameter are used. It may be.

Since the sintered compact for hard tools according to the present invention is excellent in thermal conductivity, strength and wear resistance, it is used for intermittent cutting of hardened steel and cutting of cast iron or heat resistant alloys. The above and other objects, features, aspects, and advantages of the present invention will become more apparent from the accompanying drawings.

Example 1

TiN _0.7 , Al and WC powders were mixed in a weight ratio of 6: 3: 1 and treated under vacuum at 1200 ° C. for 1 hour. The treated material is ground in a melting furnace for bowl and cemented carbide to prepare a powder having a particle diameter of 1 탆 or less. The resulting powder is then mixed with various CBN powder materials of different sizes in the proportions listed in Table 1.

The disc of WC-10 wt% Co is placed in a Mo container and filled with the mixed powder material as described above. Each container is placed in an ultrahigh pressure apparatus and treated at 50 kb for 15 minutes at 1350 ° C. to obtain a sintered body. The structure of each obtained sintered compact was observed with the scanning electron microscope, and it turns out that CBN particle is disperse | distributed uniformly through a bonding phase.

As a result of examining these sintered compacts by X-ray diffraction, peaks presumed to be TiB ₂ , AlB ₂ AlN, W, and the like were found in addition to the CBN and (Ti, W) (C, N) peaks. The atomic ratio of Ti and W measured through compound analysis was 93: 7.

In addition, it was recognized that each CBN sintered body was strongly bonded with the base material of the cemented carbide. The resulting sintered body was acted as a tip for cutting so that the tip cuts SUJ-2 steel (H _RC : 58 to 60) having an outer diameter of 10 mm with eight holes having a diameter of 10 mm at 20 mm intervals on the outer peripheral surface. Table 1 also shows the results of the cutting test.

TABLE 1

* Is a comparative example

Example 2

A binder powder material was prepared as reported in Tables 2-1 and 2-2. The binder is mixed with a CBM powder material containing particles having a particle size of 6 to 8 µm and less than 3 µm in a ratio of 7: 3 at a volume ratio of 3: 7, and sintered under ultrahigh pressure similarly to Example 1. The structure of each of the obtained sintered bodies was observed that CBN particles having a particle diameter of 3 μm or less were uniformly dispersed through the binder between or around the particles having a particle diameter of 6 to 8 μm.

Further investigation of the sintered body through X-ray diffraction revealed that the sintered body obtained through the binders Nos. 2, 3, 4, 5, 6, 10 and 11 within the scope of the present invention were carbides, nitrides, carbonaceous containing CBN and Ti. In addition to the peaks of the cargo, the peaks assumed to be peaks of TiB ₂ and AlB ₂ are shown. In addition, in the sintered body prepared through the binders 7,10 and 11, peaks of WC were observed together with the peaks.

On the other hand, in the sintered body obtained from the binder 1, the peak presumably of Ti ₂ Al ₃ Ti or Al was observed.

Next, each obtained sintered compact is used as a cutting tool, and SKD-11 mold steel having an outer diameter of 100 mm having a U-shaped groove on the outer circumferential surface is cut. Cutting conditions are as follows:

Cutting speed: 110m / min

Depth of cut: 0.2㎜

Feed: 0.15 mm / rev.

Table 3 shows the wear resistance results of the tip tested through the cutting test.

The crater resistance is evaluated by performing the same cutting test for 20 minutes under the same conditions on a circular bar of SKD-11 steel without grooves (H _RC : 60). Table 3 shows the results.

TABLE 2-1

* Is a comparative example

Table 2-2

* Is a comparative example

TABLE 3

* Is a comparative example

Example 3

The powder materials recorded in Tables 4-1 and 4-2 were mixed at the above-mentioned ratios and treated under vacuum at 1350 ° C. for one hour. These materials are ground through a melting furnace for bowl and cemented carbide. Next, the obtained powder material is mixed with a CBN powder material having a particle size of 1 to 2 µm and a volume ratio of 4: 6, and the mixed powder material is filled into the Mo container. Each vessel was placed in a high pressure apparatus and treated at a temperature of 1400 ° C. and a pressure of 50 kb for 20 minutes to obtain a sintered body.

The structure of each obtained sintered body was observed by SEIM, and found that CBN particles were uniformly scattered through the binder. Investigation of each sintered body by X-ray diffraction showed peaks presumed to be borides of CBN, (Ti, W) N or (TiW) C, TiB ₂ , AlB ₄ or AlN and W.

The cutting tool was manufactured from the sintered body, and SKD-11 steel (H _RC : 58-60) having an outer radius of 100 mm having a groove of 20 mm on the outer circumferential surface was cut. Cutting conditions are the same as in Example 1. Table 4-1 also shows the cutting test results.

Table 4-1

* Is a comparative example

Table 4-2

* Is a comparative example

Example 4

Ti-containing carbides, nitrides and carbonitrides, and mixed powder materials of aluminum and tungsten carbide are prepared as shown in Table 5. Next, the CBN powder material containing particles of 4 to 8 µm, 2 to 4 µm, and 2 µm or less at a ratio of 3: 5: 2 is mixed with the binder powder at the ratio shown in Table 5. The mixed powder material thus obtained is placed in a Mo container and heated in a vacuum furnace at a vacuum degree of 10 ⁻⁴ torr for 20 minutes at 1000 ° C. in order to degas each of them, and then the mixed powder material is sintered under a pressure of 55 kb and a temperature of 1400 ° C.

As a result of irradiating each of the obtained sintered compacts with a scanning electron microscope, it was observed that CBN particles having a particle size of less than 4 μm were arranged through a binder between or around CBN particles having a particle size of 4 to 8 μm.

Examination of each sintered body by X-ray diffraction showed that each sintered body showed peaks of AlB ₂ , TiB ₂ , TiN, W, and WB with peaks of carbide or carbonitride containing Ti and CBN. It became. In addition, in each sintered compact, the atomic ratio of Ti and IVa, Va, or VIa group metal was measured by chemical analysis. The atomic ratio in samples ba-5 was 93: 7 while the atomic ratio in samples ba-1, ba-2, ba-3, ba-4, ba-6 and ba-7 was 82:28.

Next, the cutting edge was made of a sintered body, and the SKD-11 steel material (H _RC : 59) having a U-shaped groove of 10 mm in the lock was formed in four places on the outer circumferential surface. Cutting conditions are as follows:

Cutting speed: 100m / min

Depth of cut: 0.2㎜

Feed speed: 0.1 mm / rotation

Cutting method: Dry

1 shows the cutting test results.

TABLE 5

* Is a comparative example

** Volume%

Example 5

CBN powder material obtained by mixing CBN particles of different sizes as shown in Table 6-1 at the ratio shown in Table 6-1, and the binder powder recorded in Table 6-2 at the CBN powder content shown in Table 6-1. Mixing with the material gave a sintered body similarly to Example 4.

The sintered compact thus obtained was evaluated by X-ray diffraction. AlB ₂ , AlN, TiB ₂ and WB ₂ with peaks of CBN and (Ti, W) (C, N) in samples ba-8, ba-9, ba-10, ba-11 and ba-12 It was observed to show the estimated peak with the sintered body. In the sintered compact of sample ba-13, the peaks of CBN, (Ti, W) (C, N) AlB ₂ , AlN and TiB ₂ were observed.

In each of the samples ba-8 to ba-11, the atomic ratio of Ti to the Group IVa, Va or VIa metal of the periodic table was 91: 9. On the other hand, the atomic ratio of the sintered body of sample ba-12 was 55:45, while the sintered body of sample ba-13 was 90.4: 2.6.

Next, the structure of each sintered body was examined, and it was observed that the CBN particles were partially bonded in samples ba-8, ba-9 and ba-13. On the other hand, in samples ba-10, ba-11 and ba-12, the fine CBN particles were uniformly filled around or between the thick particles, and the fine CBN particles were bound through the binder.

The above-mentioned sintered body was processed by cutting edges to cut SNCM-9 steel materials (H _RC : 58 to 60) having key grooves on the outer circumferential surface. Cutting conditions were as follows.

Cutting speed: 120m / min

Depth of cut: 0.1 m

Feed speed: 0.1 mm / rotation

Cutting method: Dry

The results of the cutting test are shown in Table 7.

Table 6-1

* Is a comparative example

Table 6-2

* Is a comparative example

TABLE 7

* Is a comparative example

Example 6

In order to investigate the abrasion resistance of the sintered bodies obtained in Examples 4 and 5, the cutting test was subsequently performed on the SKD-11 steel material. The strength of the material was H _RC 60. Cutting conditions were as follows:

Cutting speed: 100㎜ / min

Depth of cut: 0.2㎜

Feed speed: 0.1 mm / rotation

Cutting method: Dry

Cutting time: 10 minutes

2 shows the crater depth of the rake face.

Example 7

Carbide and carbonitride powder containing Ti was mixed with aluminum powder and tungsten carbide powder, preheated at a high temperature of 1200 ° C., and preliminarily crushed by a cement mill of cemented carbide. The average particle diameter 1 was recorded in Table 8. A binder powder material of less than μm was obtained. The obtained binder powder material was mixed with 70 volume% of CBN powders containing 30 volume% of CBN powders containing CBN particles of 4-10 micrometers, 2-4 micrometers, and less than 2 micrometers in a ratio of 5: 4: 1, and Example 4 Similarly, it was placed in a Mo container and sintered under a pressure of 40 Kb and a temperature of 1200 ° C.

The sintered body thus obtained was judged through X-ray diffraction, and AlB ₂ , AlN together with the peaks of carbonitrides containing CBN and Ti in the sintered body produced by the binders ba-14 to ba-19 belonging to the scope of the present invention. Borides of W and / or peaks presumed to be of W and WC were observed. On the other hand, the peak of Al ₃ Ti is observed together with the peaks described above in the sintered body made of the binder ba-20 and the large peak of WC is observed with the peaks described above in the sintered body made of the binder ba-20 and the large peak of WC The peak of Ti ₃ Al was observed in the sintered body of binder ba-22 and the peak of Al ₃ Ti was observed in the sintered body of binder ba-23.

The structure of each sintered body was observed to find that fine CBN particles were arranged and dispersed between or around coarse CBN particles through a binder.

Next, each sintered compact was produced with a cutting tool, and a material cutting test was performed. The cutting material was composed of SUJ-2 steel materials (H _RC : 59-61) each composed of a cylinder type (inner diameter: 25 mm) having a key groove on the inner circumferential surface. Cutting conditions were as follows.

Cutting speed: 150m / min

Depth of cut: 0.2㎜

Feed Speed: 0.15㎜ / Rotation

Table 9 shows the cutting test results.

TABLE 8

** Ti: Atomic ratio of Group IVa, Va or VIa metals

* Is a comparative example

TABLE 9

* Is a comparative example

Example 8

(Ti _0.9 , W _0.1 ) (C _0.9 , N _0.1 ) _0.85 , TiAl ₃ and WC were mixed at a weight ratio of 4: 1: 1 and homogenized in a nitrogen gas of 1 Torr for 1 hour at a temperature of 1300 ° C. The powder thus obtained was ground to an average particle diameter of less than 1 µm using a melting furnace and cemented carbide balls. Analysis of the obtained binder showed that it contained 30% by weight of Al. The atomic ratio of Ti: W was 87:13.

The above binder was mixed with a CBN powder having a particle diameter of less than 6 µm and a volume ratio of 30:70, put in a Mo container, and sintered at a pressure of 50 kb and a temperature of 135 ° C. for 15 minutes.

When the obtained sintered body was judged by X-ray diffraction, when the peaks presumed to be CBN, (Ti, W) (C, N), AlB ₂ , AiN, TiN and WB ₂ were observed in the sintered body, Al ₂ Ti was not observed. Did.

When a cutting tool was produced from this sintered body and subjected to a cutting test similarly to Example 4, the performance of this cutting tip was about 3.2 times the performance of Sample ba-2 in Example 4.

Example 9

Nitride powder and carbonitride powder containing Ti were mixed with aluminum powder and WC powder, and ground through a melting furnace and a cemented carbide bowl to produce a binder powder of less than 1 μm in average particle diameter as described in Table 10. In sample Ca-7 shown in Table 10, the WC powder was not mixed at all. These binder powder materials were mixed at a volume ratio of 30:70 with CBN powder mixed with CBN particles of 8 to 6 µm and 2 to 3 µm at a ratio of 2: 1 to prepare a mixed powder material. These mixed powder materials were placed in a Mo container on which a cemented carbide disc of WC-12 wt% Co composition was placed. Each vessel is introduced into a high pressure / temperature apparatus and sintered for 15 minutes at a pressure of 50 kb and a temperature of 1280 ° C.

When the obtained sintered body was irradiated by X-ray diffraction, peaks were assumed to be borides of Ti, TiB ₂ , AlB ₂ , AlN and W or CBN, nitride or carbonitride containing W in samples Ca-1 to Ca-7. Stones were observed in the sintered body. Peaks of CBN, (Ti, W) (C, N) AlB ₂ , AlN, WC and a small amount of TiB ₂ were observed in sample Ca-8. CBN, TiN, AlB ₂ , AlN and TiB ₂ These peaks were detected in sample Ca-9, while peaks of CBN, TiB ₂ , WB and small amounts of AlN and AlB ₂ were detected in sample Ca-10, while CBN, ( The peaks of Ti, W) (C, N), TiB ₂ , AlB ₂ , AlN, WB and Al ₃ Ti were detected in sample Ca-11 and CBN, (Ti, W) (C, N), TiB ₂ , Peaks presumed to be AlB ₂ , AlN, WB and WC were detected in sample Ca-12.

Next, the composition of each sintered body was observed through a scanning electron microscope, and it was found that fine CBN particles were arranged between or around the coarse CBN particles through the binding phase.

Table 11 shows the beaker hardness of the sintered compact. The cutting test is carried out with a cutting tool made of sintered body. Each workpiece was an SCM-440 (H _RC : 59-62) cylinder having a diameter of 80 mm having four grooves on its outer circumferential surface.

Cutting conditions were as follows:

Cutting speed: 130m / min

Depth of cut: 0.15㎜

Feed rate: 0.10 mm / rotation

Table 11 also shows the time measurement results for tip failure.

TABLE 10

** Ti: Atomic ratio of Group IVa, Va or VIa metals

* Is a comparative example

TABLE 11

* Is a comparative example

Example 10

(Ti _0.85 , W _0.15 ) (C _0.1 , N _0.9 ) _0.75 , Al and WC powders were mixed and ground to obtain a binder powder having a particle diameter of less than 1 μm. The composition of this powder was 60% (Ti _0.85 , W _0.15 ) (C _0.1 , N _0.9 ) _0.75 -24 wt% Al-7 wt% WC. The atomic ratio of Ti.W was 81.7: 18.3.

Such binder powder material was mixed with the CBN powder material in the proportions reported in Table 12 and sintered under ultrahigh pressure similarly as in Example 9.

Each obtained sintered compact was produced with the cutting tool, and the cutting test was done. The workpiece was formed of a circular cross-section rod of SUJ-3 material (H _RC : 58-62) having a diameter of 480 mm, each having four holes having a diameter of 4.5 mm on the outer circumferential surface at intervals of 10 mm along the circumference. Cutting conditions are as follows.

Cutting speed: 120m / min

Depth of cut: 0.2㎜

Feed Speed: 0.09㎜ / Rotation

Table 12 also shows the results of measuring the time taken for the cutting edge to break.

TABLE 12

* Is a comparative example

Example 11

Binder material was prepared as recorded in Table 13. These binder materials were mixed with particles having a particle diameter of 8 μm, 3 to 5 μm, and 2 μm or less at a volume ratio of 30:70 and a CBN powder material mixed at a ratio of 5: 3: 2 to prepare a mixed powder material. These powder materials were filled in a Mo container and sintered under an ultrahigh pressure state at a temperature of 1300 ° C. and 50 kb.

The sintered body thus obtained was judged by X-ray diffraction, and it was observed that the sintered body showed peaks based on the material as shown in Table 14.

Each sintered body was made with a cutting tool, and the circular cross-section rod of SKD-11 material (H _RC : 60-63) which has axial groove | channel was cut in four places of the outer peripheral surface. Cutting conditions were as follows:

Cutting speed: 120m / min

Depth of cut: 0.2㎜

Feed Speed: 0.2㎜ / Rotation

Table 14 shows the cutting test results.

TABLE 13

* Is a comparative example

TABLE 14

* Is a comparative example

Example 12

Nitride or carbonitride powder containing Ti was mixed with aluminum powder and WC powder and dispersed through a melting furnace and a cemented carbide ball to produce a binder powder having an average particle diameter of less than 1 μm as reported in Table 15. Such a binder powder material was mixed with a CBN powder material having a particle diameter of less than 1.5 µm at a volume ratio of 45:55 to form a mixed powder material. These mixed powder materials were filled in a Mo container in which a cemented carbide disk of WC-100 wt% Co was placed. Each vessel was then introduced into an ultrahigh pressure / temperature apparatus and sintered for 30 minutes at a pressure of 53 kb and a temperature of 1350 ° C.

The sintered bodies were irradiated by X-ray diffraction to observe peaks of CBN, carbides, nitrides and carbonitrides containing Ti in all the sintered bodies. A boride or W of W was recognized along with the peaks presumed to be TiB ₂ , AlB ₂ and AlN and the materials described above in samples da-1 to da-7. In addition, peaks presumed to be borides of AlB ₂ , AlN, WC, W and small amounts of TiB ₂ were observed with peaks of CBN and (Ti, W) (C, N) in sample da-8 and CBN, Ti Peaks of (C, N), TiB ₂ , AlB _2, and AlN are observed in sample da-9, while peaks suspected of borides of CBN, (Ti, W) (C, N), TiB ₂ and W And small amounts of AlB ₂ and AlN were observed in sample da-10, and peaks of CBN, (Ti, W) (C, N), AlN, AlB ₂ , TiB ₂ , W boride, and Al ₃ Ti were observed. It was observed in sample da-11.

Next, the structure of each sintered body was observed with a scanning electron microscope to find that the fine CBN particles were bonded to each other through a bonding phase. Table 16 shows the results of measuring the beakers hardness of these sintered bodies.

The red tool was made from each sintered body, and the circular cross-section rod of SNCM-415 material (H _RC : 58-61) of diameter 100mm which has two axial grooves on the outer peripheral surface was cut | disconnected.

Cutting conditions were as follows:

Cutting speed: 80m / min

Depth of cut: 0.2㎜

Feed Speed: 0.15㎜ / Rotation

Cut Prevention: Dry

Table 16 shows the cutting time measurement results until breakage.

TABLE 15

* Is a comparative example

TABLE 16

* Is a comparative example

Example 13

(Ti _0.9 , W _0.1 ) (C _0.1 , N _0.9 ) _0.7 , Al and WC powders were mixed to obtain a binder powder having a particle diameter of less than 1 μm. The composition of the binder powder was 57 wt% (Ti _0.9 , W _0.1 ) (C _0.1 , N _0.9 ) _0.7 -33 wt% Al-10 wt% WC. The atomic ratio of Ti and W in the binder was 84.6: 15.4. The binder material of such powder and the CBN powder material were mixed as recorded in Table 17 to prepare a mixed powder material. As mentioned in Table 17, Sample da-18 was prepared as CBN powder having a particle size of 3-5㎛.

The mixed powder material thus obtained was sintered under ultrahigh pressure similarly to Example 12 to obtain a sintered body. The cutting tool was manufactured using these sintered bodies.

The cross section of the circular cross-section rod made of SKD 11 (H _RC : 50-62) having a diameter of 100 mm was cut using the manufactured cutting tools. Cutting conditions were as follows:

Cutting speed: 150㎜ / min

Depth of cut: 0.5㎜

Feed speed: 0.1㎜ / tip

Cutting speed: dry

Table 17 shows a number of possible cut times.

TABLE 17

* Is a comparative example

Example 14

A particle diameter of less than 1 μm prepared a binder powder material as recorded in Table 18. These binder powders were mixed with CBN powder materials having a particle diameter of less than 1 mu m at a volume ratio of 43:57 to obtain a mixed powder material. These mixed powder materials were placed in Mo containers and sintered under ultrahigh pressure. Sintering was carried out with the mixed powder material at 45 kb for 30 minutes at 1330 ° C. Each obtained sintered body was examined by X-ray diffraction, and the peaks of the materials shown in Table 19 were observed.

These sintered bodies were made of cutting tools and subjected to cutting tests. The workpiece was formed of a SUJ-2 circular cross-section rod having a diameter of 80 mm and had four holes having a diameter of 6 mm at intervals of 10 mm about the axis in the radial direction. Cutting conditions were as follows:

Cutting speed: 100m / min

Depth of cut: 0.2㎜

Feed speed: 1.10 mm / rotation

Cutting method: Dry

Table 19 shows the cutting times for tip failures measured in the cutting test.

TABLE 18

* Is a comparative example

TABLE 19

* Is a comparative example

Although the present invention has been described above and in detail, it is to be understood that the invention is not to be limited to the examples and examples, but to limit the scope and spirit of the invention in the appended claims.

Claims (15)

A sintered body obtained by high-temperature sintering of a mixed powder comprising cubic boron nitride of 50 to 70% by volume and the remainder of the binder, wherein the binder contains 20 to 50% by weight of Al, and includes TiNz, Ti (C, N) z, TiCz, (Ti, M) Cz, (Ti, M) (C, N) z and (Ti, M) N _Z , (M represents a transition metal of group IVa, Va or VIa of the periodic table excluding Ti, Z 0.5

Z

It is in the range of 0.85) containing at least one Ti compound, the atomic ratio of the Ti content in the binder and the transition group metals IVa, Va, VIa is 2/1 to 97/3, tungsten A sintered compact for high hardness tools, which is contained in the form of a compound, a W compound and / or WC, and has a total tungsten concentration of 4 to 40% by weight. The sintered compact for hard tools according to claim 1, wherein the sintered compact has a continuous bonding phase and fine cubic boron nitride particles are squarely filled around or between the coarse cubic boron nitride particles. The sintered compact for hard tool according to claim 1, wherein the tungsten is mixed in the form of tungsten boride or WC. The sintered compact for high hardness tool according to claim 1, which is mixed in the form of the Al compound. The method of claim 1, wherein the cubic boron nitride contains about 65 to 75% by volume, the binder contains about 20 to 35% by weight of Al, and the Ti compound is (TiCz, MC) y _y- (MN) _1-y or (Ti, M) (Cy, N _1-y ), where M represents a Group IVa, Va or VIa transition metal element other than Ti and 0 <y

0.3), the sintered compact for high hardness tool, characterized by the above-mentioned. The method according to claim 1, wherein the cubic boron nitride containing 65 to 75% by volume, the binder contains 25 to 50% by weight of aluminum, the Ti compound is (TiCz, MC) _y- (MN) _1-y Or (Ti, M) (Cy, N _1-y ), where M represents a group IVa, Va, or VIa transition metal of the periodic table excluding Ti, wherein 0.3 <y

1.0), the sintered compact for high hardness tool, characterized by the above-mentioned. The sintered compact for high hardness tools according to claim 1, wherein the cubic boron nitride is contained in an amount of 50 to 65% by volume, and an average particle diameter thereof is less than 2 m. The sintered compact for tool according to claim 1, wherein the cubic boron nitride powder has a particle diameter of less than 1 µm. 50 to 75% by volume of cubic boron nitride; 20 to 50% by weight of Al, TiNz, Ti (C, N) z, TiCz (Ti, M) Cz, (Ti, M) (C, N) z and (Ti, M) Nz (where M Indicates a Group IVa, Va or VIa transition metal on the periodic table excluding Ti, where Z is 0.5

z

0.85 is in the range), and the atomic ratio between Ti content in the binder and the IVa, Va, VIa group transition metal in the binder is 2/1 to 97/3, tungsten is 25 to A binder containing 50 vol.% Of mixed powder in the form of the Ti compound, W compound and / or WC, and a process of obtaining the whole powder and the mixed powder having a pressure of 20 kb or more with stable CBN and a tungsten concentration of 40 to 40 wt%. A method for producing a sintered compact for hard tool, characterized by comprising a step of sintering under ultrahigh pressure conditions at a temperature of 1000 ° C to 1500 ° C. 10. The method of claim 9, wherein the tungsten is mixed in the form of tungsten boride or WC. 10. The method for producing a sintered compact for hard tool according to claim 9, wherein the Al is mixed in the form of an Al compound. The method according to claim 9, wherein the cubic boron nitride containing 65 to 75% by volume, the binder contains 20 to 35% by weight of Al, the Ti compound is (TiCz, MC) _y- (MN) _1-y Or (Ti, M) (C _y , N _1-y ), where M represents a Group IVa, Va or VIa transition metal element of the periodic table excluding Ti, and 0

y

0.3) is a method for producing a sintered compact for high hardness tool. The method according to claim 9, wherein the cubic boron nitride containing 65 to 75% by volume, the binder contains 20 to 50% by weight of Al, the Ti compound is (TiCz, MC) _y- (MN) _1-y Or (Ti, M) (Cy, N _1-y ), where M represents a Group IVa, Va or VIa transition metal element of the periodic table excluding Ti, and 0.3

y

1.0), the method for producing a sintered compact for high hardness tool. The method for producing a sintered compact for hard tool according to claim 9, wherein 50 to 65% by volume of the cubic boron nitride powder is contained, and the average particle diameter of the powder is generally less than 2 m. The method for producing a sintered compact for high hardness tool according to claim 9, wherein the cubic boron nitride powder has an average particle diameter of less than 1 m.

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