JPS63295482A - High-hardness composite sintered body - Google Patents

Abstract

PURPOSE:To provide a high-hardness composite sintered body having high joint strength and high rigidity as a composite body by joining metal, alloy or sintered hard alloy layers having through-holes to in a specific form to both faces of a high-hardness sintered body essentially consisting of diamond and/or high-pressure phase boron nitride. CONSTITUTION:This high-hardness composite sintered body is constituted by joining the metal, alloy or sintered hard alloy layers having the through-holes to both faces of the high-hardness sintered body layer 1 essentially consisting of the diamond and/or high-pressure phase boron nitride and packing the above- mentioned high-hardness sintered body into the above-mentioned through-holes. Sheets consisting of a metal selected from molybdenum, tungsten, tantalumn, and niobium or an alloy essentially consisting thereof are preferably interposed as the intermediate layers 3 between the high-hardness sintered body layer 1 and the metal, alloy or sintered hard alloy layers 2. The deterioration in the heat resistance and the wear resistance of the high-hardness sintered body layer 1 and the deterioration in the strength of the joint boundary thereof are thereby prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high-hardness composite sintered body containing diamond, high-pressure phase boron nitride, or both.

More specifically, the present invention relates to a high-hardness composite sintered body that is used as a tip by brazing both sides of the shank of a rotary tool such as a drill or an end mill.

[Conventional technology]

A high-hardness sintered body (hereinafter referred to as D713) mainly composed of diamond and/or high-pressure phase boron nitride used for drilling
There are two types of N sintered bodies: a two-layer structure in which cemented carbide or metal is bonded to one side, and a multi-layer structure in which cemented carbide is bonded to both sides through an intermediate layer. These are brazed to the shank and used as rotating cutting tools.

The cemented carbide that makes it possible to braze the D/BN sintered body and serves as a supporting material for reinforcement is usually a homogeneous flat plate.

[Problem that the invention seeks to solve]

Since one side is made of cemented carbide, the brazing is only done on one side, so the joint strength of the brazing is insufficient, and it may peel off from the shank during heavy-duty drilling. When one side is made of metal or alloy, the joint strength of the surface is further weakened by brazing, and the joint with the D/BN sintered body is inferior to that of cemented carbide.

Therefore, the D/
A type was proposed in which cemented carbide was bonded to both sides of a BN sintered body. However, the inventor of this case is JP-A-57-66805.
As described in the issue, we tried to make a three-layer laminated sintered body made by intervening and adhering a D/BN sintered body between two cemented carbide layers, but the D /BN
Horizontal cracks appeared in the sintered body, making it extremely difficult to ensure stable quality. This is thought to be because the D/BN sintered body and the cemented carbide have significantly different coefficients of thermal expansion, which causes a tensile force to act in a direction perpendicular to the joint surface.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 61-270271, we selected all cemented carbide alloys whose coefficient of thermal expansion is similar to that of the diamond sintered body, and an intermediate layer between the two layers that does not allow iron group metals to pass through. A layered and bonded sandwich structure has been proposed. However, such a composite naturally has the disadvantage that the metal and cemented carbide bonded to the intermediate layer and the outside thereof are limited to those having a coefficient of thermal expansion close to that of the diamond sintered body. Particularly when manufacturing a composite with a large diameter, the cemented carbide selected above has poor toughness and is prone to cracking due to the uneven distribution of pressure and temperature that is difficult to avoid in a reaction vessel placed at ultra-high pressure and high temperature. Furthermore, the bonding strength between the intermediate layer and the cemented carbide is insufficient, making it impossible to obtain a satisfactory composite. We also tried to make a composite structure with metal on both sides, but since the Young's modulus of metal is smaller than that of cemented carbide, it tends to warp after hot pressing, and if it is made into a cutting tool, it will be susceptible to shock during processing. On the other hand, it had the disadvantage of increasing distortion.

Furthermore, as mentioned in JP-A No. 60-44204, when a soft metal having a Young's modulus of 45 x 106 psi or less is bonded to both sides, horizontal cracks and the like in a hard sintered body are less likely to occur than in the case of cemented carbide. Cracks near the bonding interface were less likely to occur, but could not be completely prevented. Furthermore, since the Young's modulus is smaller than that of cemented carbide, warping and distortion occur during manufacturing, which poses a problem when processing into tools. Furthermore, since the rigidity and heat resistance are reduced, there are restrictions on the processing conditions as a tool.

The purpose of the present invention is (a) to firmly bond the D/BN sintered body and the metal 5 alloy or cemented carbide (hereinafter referred to as the substrate). The purpose is to provide a high-hardness composite sintered body that does not cause peeling or cracking, 3) brazes with the shank, and has sufficient adhesion strength for use as a tool, and 2) has high rigidity as a composite body.

[Means for solving problems]

As a result of various improvements, the inventor of the present invention found that when metals, alloys, or cemented carbide are simply directly joined from both sides, the former has a difficulty in terms of rigidity, while the latter has a large Young's modulus and is suitable as a support material. , as mentioned above (if the D/BN sintered body is simply bonded as a flat plate, cracks will occur, but the D/BN sintered body is inserted by making many through holes in the substrate and filling the holes). What kind of metal, alloy,
The present invention was completed by discovering that no cracks occur even when cemented carbide is used. In other words, the gist of the present invention is a composite sintered body in which metal, alloy, or cemented carbide layers having through holes are bonded to both sides of a high-hardness sintered body layer mainly composed of diamond and/or high-pressure phase boron nitride. The high-hardness composite sintered body is characterized in that the through hole is filled with the high-hardness sintered body.

[Structure of the invention]

The present invention will be explained in detail below.

The D/BN sintered body is a high hardness sintered body mainly composed of diamond and/or high-pressure phase boron nitride. is included. As is well known, sintered bodies of diamond and high-pressure phase boron nitride require a binder phase, and this binder phase may include At, Ni, Co,
Metals such as Mn and/or 3b, 4a, 4b, 5a,
Nitride, carbide, carbonitride, boride of group 6a elements,
Ceramics consisting of oxides are used. Set and D/
The proportion of the binder phase in the BN sintered body is 5 to 80% by weight.

The material of the outer substrate to be joined to the D/BN sintered body includes cemented carbide, iron group metals and their alloys, 4a, 5a, and 6a metals, gold, silver, copper and its alloys, titanium and its alloys, etc. can be mentioned. Among these, when silver brazing is applied to the tool shank, cemented carbide, iron group metals and alloys thereof, molybdenum and alloys thereof, tungsten and alloys thereof, etc. are preferable, as long as the strength and brazing properties are satisfied.

The materials of the substrates bonded to both sides of the Naori/BN sintered body do not necessarily have to be the same. For example, one may be a cemented carbide and the other molybdenum, or one may be a cemented carbide and the other may be an alloy of an iron group metal.

The structure of the D/BN sintered body and the substrate can be explained using the drawings, for example, as shown in FIGS. 1 and 2, and as shown in FIG.
The cross section indicated by the arrow I' is shown in FIG. That is, D
/BN sintered body A substrate 2 is bonded to the sintered body side, and the substrate 2 has a through hole, and this through hole is filled with the D/BN sintered body. In this way, the metal, alloy, or cemented carbide used for the substrate 2 does not need to be particularly limited in its coefficient of thermal expansion, and in the case of cemented carbide, it can be used in a wide range of Co content ranging from 5 to 15% by weight. . Various conditions required for the tool, such as composite size, thickness, D/B
The composition of the substrate and the size and number of holes can be appropriately selected in consideration of the hardness and thickness of the N sintered body. The shape of the hole is not particularly limited, but a circular hole is generally easy to process. Also, regarding the diameter, diameter 1
~4■ is preferable. If it is less than this, the raw material will not be uniformly filled into the holes, and if it is too large, the stress distribution will become macroscopically non-uniform.

When subdivided, various non-uniformities occur.

The area ratio of the holes to the entire substrate is preferably 20 to 80 inches. If this ratio is small, horizontal cracks are likely to occur in the structure of the D/BN sintered body, while if it is too large, the adhesive strength during brazing will be low, making it unsuitable.

The thickness of the substrate is 0.5 in the case of cemented carbide to increase rigidity.
The thickness is preferably 0.2 to 1.0 mm or more in the case of metals or alloys, since rigidity decreases if the thickness is made too thick.

Furthermore, it is also effective to provide an intermediate layer made of a thin plate between the D/BN sintered body and the substrate. In other words, in the case of a cemented carbide substrate, internal cobalt tends to diffuse into the D/B N sintered body during hot pressing, and this
This causes deterioration of the heat resistance and wear resistance of the BN sintered body. Furthermore, even when the substrate is a metal or alloy, the metal elements diffuse into the D/BN sintered body and react, which may deteriorate the strength of the bonding interface. For the purpose of preventing these deteriorations, a thin plate made of a metal selected from tungsten, molybdenum, tantalum, and niobium or an alloy containing these as main components can be placed in the middle. This intermediate layer is extremely effective when the substrate is an iron group metal. For molybdenum or tungsten substrates, especially for diamond sintered bodies, molybdenum,
Since the diffusion of tungsten increases, it is preferable to arrange tantalum and niobium in the middle.

The thickness of these intermediate layers is preferably 0.05 to 0.2 cm. If it is less than 0.05 mm, the diffusion prevention effect will be poor;
If it exceeds Zwm, the rigidity will be reduced, which is not preferable.

Furthermore, iron group metals and their alloys can also be used as the material for the intermediate layer. D/BN sintered bodies and substrates when the amount of iron group metals and their alloys contained in the raw materials of D/BN sintered bodies and cemented carbide, or other metals and alloys with a melting point of 1500°C or less is small. The toughness of the material is poor, and the bonding strength at the interface is also weak. This drawback can be improved by disposing an iron group metal or its alloy between these two layers and diffusing it during hot pressing. Regarding the thickness, O, OS ~ 0.2 tm
is preferred. If it is less than 0.0511II, there will be no effect on toughness or joint strength, and if it exceeds 0.2 m, the rigidity will be small and the heat resistance will be poor. FIG. 3 shows a cross-sectional view of the composite sintered body when an intermediate layer is provided. FIG. 3 is a sectional view taken along the arrow 1-1 in FIG.
is intervening.

In the multilayer composite of 3 to 5 layers as described above, peeling and horizontal cracking of the high hardness composite sintered body do not occur.
The reason may be as follows.

The composite that has been cooled after hot pressing has residual stress due to the difference in thermal expansion coefficients. Usually, the value α of the thermal expansion coefficient of the high-hardness composite sintered body produced is as follows: D/BN sintered body α1 = 4 to 6XIO-6/l
(800℃O average) Cemented carbide 6M1=5~7×lO
/'C (average of 80°C) MOIJ ly"7 (1
M2==5.5XIO-'/'IC(80(F(D average) Cobalt 6M3=16.8X10/l
(750CO average) Hastelloy CαM4=14.5×
lO/c (8oooD average) is generally α1 × αe. Therefore, during the cooling process of the hot press, compressive stress occurs in the D/BN sintered body and tensile stress occurs in the cemented carbide. In the conventional technology in which the cemented carbide layer is a flat plate without through holes, stress is concentrated near the interface at the outer periphery, and an opposite tensile force acts in the center, causing splitting. The clutch 4 receives the force as shown in the figure. However, in the composite sintered body according to the present invention, each stress is divided, and stress is difficult to concentrate on the outer peripheral portion. Furthermore, the D/BN sintered body protrudes into the substrate at a solid portion, and since it functions as a so-called stud, it has sufficient adhesion and holding power to withstand shearing force and tensile force. In addition, when brazed and used as a cutting tool, this protrusion improves heat conduction to the shank and helps extend the life of the cutting edge.

[Example 1] Cubic boron nitride powder with a particle size of 4μ, 70 weight #chi, particle size of 1μ
7.0 g of a mixed powder of 20% by weight of Tic powder and 10% by weight of At powder was placed in a hexagonal boron nitride sleeve with an inner diameter of 30 sam and a WC-6%C with a thickness of 1.0 mm.

They were placed between cemented carbide plates and lightly compressed.

The cemented carbide plate has 35 through holes with a diameter of 3 cm at equal intervals. These are incorporated into a graphite heater and heated to 55Kb and 1400℃ using an ultra-high pressure/high temperature generator.
It was held for 30 minutes and sintered. Polish the outer periphery and make the outer diameter 29
m, the thickness of the cubic boron nitride heating body is 2. A composite sintered body with a total thickness of 4 cm was obtained. No cracks were observed on the outer periphery, and there was no warpage. The cemented carbide on both sides is ground, cut into the specified shape, and then brazed to the shank.
The drill shown in Figure 5 (a) # (b) was made and the hardness was H.
I tried drilling a RC60 5KD-11 steel plate, and the results were very good.

In addition, a high hardness composite sintered body cut into 5m square pieces was coated with 6% Co
The bending strength was measured as shown in FIG. 6. As a result, the peeling strength was 2 from one wax surface.
It was 8 kg/1lII2. This indicates that there are no latent cracks, and the strength is sufficient for practical use.

[Example 2] 90% by weight of diamonds with a particle size of 5 to 10μ and 10% of CO powder
A mixture of % by weight was prepared. Inside a hexagonal boron nitride sleeve with an inner diameter of 23 mm, a Ta foil with a thickness of 50 mm is placed on the inside, and a set of cemented carbide of WC-6% CO with a thickness of 1.01 m is placed on the outside, and the mixed powder is placed from above and below. It was placed between the two and compressed lightly. The Ta foil and the cemented carbide plate were brought into close contact with each other, and 90 through holes each having a diameter of 1.5 wm were equally spaced. These were assembled into a graphite heater and held at 6° Kb and 1500° C. for 60 minutes in the same apparatus as in Example 1 to obtain a composite sintered body.

The thickness of the diamond sintered body is 1.5 m, the total thickness is 3 m,
No peeling or cracking was observed at 5 sm.

A drill similar to that in Example 1 was made and a large number of 10% St aluminum alloy plates were drilled, and the drilling was performed with extremely high precision, with no defects occurring at the cutting edge.

[Example 3] High-hardness composite sintering was performed in the same manner as in Example 1 except that the substrates on both sides were made of WC-15% Co cemented carbide with a thickness of 3 mm and a molybdenum plate with a thickness of 0.5 sam. created a body. There were no cracks in the sample after polishing, and even when the cut pieces were brazed on both sides to the shank, no new racks were observed and the adhesive strength was sufficient.

[Examples 4 to 6] Table 1 shows examples in which the interlayer is used.

The conditions for producing the high-hardness composite sintered body were the same in Examples 4 and 5 as in Example 1, and the same in Example 6 as in Example 2. The components of Hastelloy C are Ni55, Cr16%,
Mo: 17%, Fe: 5%, W: 5%.

[Comparative Example 1] We-6% Co cemented carbide plate used in Example 1
1. All except for using the flat plate without making any through holes.
“A composite sintered body of cubic boron nitride was made in the same manner as in Example 1. This composite sintered body had racks as shown in Figure 4 and could not be used as a cutting tool. .

[Comparative Example 2] A mixed powder of 80% by weight of cubic boron nitride, 14% by weight of TiN, and 6% by weight of At was placed in a hexagonal boron nitride sleeve with an inner diameter of 30 m+. was sandwiched between 0.5 m thick molybdenum plates from both sides and lightly compressed.

Sintering was carried out under the same conditions as in Example 1, and when the composite sintered body was taken out and observed, the center was slightly swollen in a convex shape, and cracks were larger than in the center of the cubic boron nitride sintered body. It got in and peeled off easily.

[Example 7] 70% by weight of cubic boron nitride powder with a particle size of 4μ.

20% by weight of Tie powder with a particle size of 1 μm, At powder powder, and 1 μm of Tie powder with a thickness of 0.5% in an electric arsenic sleeve. 5- molybdenum plates C were placed between them and lightly compressed. The molybdenum plate has 35 through holes C with a diameter of 3 m at equal intervals. These were assembled in a graphite heater and heated to 55Kb, 1400C using an ultra-high pressure/high temperature generator. It was held for 30 minutes and sintered. The outer peripheral portion was polished to obtain a composite sintered body having an outer diameter of 29 m, a cubic boron nitride firing body thickness of approximately 2.0 m, and a total thickness of 31 al. There were no cracks near the joint or in the center, and the molybdenum on the same surface was ground and cut into a predetermined shape, and then brazed to the shank as shown in Figure 5 (a).
The drill shown in b) was made. Adhesion is strong and HRC
60 SUJ steel could be easily drilled.

[Example 8] 90% by weight of diamonds with a particle size of 5 to 10μ and CO powder 1
A mixture of 0 wt. Inside a hexagonal boron nitride sleeve with an inner diameter of 27g and a tantalum foil with a thickness of 50μm on the inside and a pair of IO tangent plates with a thickness of 0.5a on the outside, place the mixed powder from above and below so as to sandwich it lightly. Compressed. Note that tantalum foil and tungsten plate have a diameter of 1
．． There are 90 through holes of 5+m equally spaced. These were assembled into a graphite heater and pressed at 60 Kb at 1500° C. for 60 minutes using a device similar to that used in Example 7 to obtain a high hardness composite sintered body. The thickness of the diamond sintered body was 1.0 mm, and the composite had a total thickness of about 2 mm, with no cracks observed at all. I tried brazing the cut piece to the shank, but 1
It adhered strongly and could be used practically without any problems.

[Examples 9 and 10, Comparative Examples 3 and 4] Composite sintered bodies shown in Table 2 were produced and the results were observed. The conditions for creating the composite sintered body are Example 10, and Comparative Example 3 is Example 7.
, and Example 9 and Comparative Example 4 are the same as Example 8.

〔Effect of the invention〕

As described above, the high-hardness composite sintered body according to the present invention (a) can easily produce a composite sintered body consisting of a D/BN sintered body of any composition and a substrate without causing cracks. .

(b) The D/BN sintered body and the substrate are firmly bonded (
c) It has high rigidity and can be firmly brazed. (d) It is excellent as a tool.

[Brief explanation of drawings]

FIG. 1 is a front view showing one embodiment of the present invention, and FIGS. 2 and 3 are sectional views each showing one embodiment of the present invention. FIG. 4 is a cross-sectional view according to the prior art, showing stress and cracks. FIG. 5 shows a drill made using the composite sintered body of the present invention, in which (a) is a side view and (b) is a view taken along the line u-n'. FIG. 6 is a schematic diagram showing a method for measuring bending strength. 1...D/BN sintered body, 2...Substrate, 2'...Cemented carbide, 3...Intermediate layer, 4...Crack, 5...
High hardness composite sintered body, 6...shank, 7...brazing metal.

Claims (1)

[Claims] 1. A composite sintered material in which metal, alloy, or cemented carbide layers having through holes are bonded to both sides of a high-hardness sintered body layer mainly composed of diamond and/or high-pressure phase boron nitride. 1. A high-hardness composite sintered body, wherein the through-hole is filled with the high-hardness sintered body. 2. A patent in which a thin plate made of a metal selected from molybdenum, tungsten, tantalum, and niobium or an alloy containing these as main components is interposed between a high-hardness sintered body layer and a metal, alloy, or cemented carbide layer. A high-hardness composite sintered body according to claim 1. 3. A patent claim in which a thin plate made of a metal selected from iron, cobalt, and nickel or an alloy containing these as main components is interposed between the high-hardness sintered body layer and the metal, alloy, or cemented carbide layer. High hardness composite sintered body according to scope 1. 4. The percentage of holes filled with high-hardness sintered bodies penetrating the metal, alloy, or cemented carbide layer is 20 to 80% of the total area.
A high-hardness composite sintered body according to any one of claims 1 to 3.