JP2806481B2 - Plate-shaped cubic boron nitride oriented compact - Google Patents

Description

The present invention relates to cubic boron nitride suitable for use in wear-resistant mechanical materials such as grinding, cutting tools, and sliding materials, and heat dissipation substrates for semiconductors. More specifically, the present invention relates to a composite molded article in which the orientation of cubic boron nitride particles is controlled.

(Conventional technology) CBN (cubic boron nitride; the same applies to the following) has the hardness next to diamond and has thermal and chemical stability, in particular, chemical stability to iron-based work materials Is highly promising as a material for grinding and cutting tools because it is superior to diamond, and is already quite widely used.

The particle shape of general CBN is polygonal, blocky shape with almost the same distance between opposite sides.
The CBN particles are mixed with a metal, ceramics, or resin as a binder, pressurized and heated, cut, and finished to a desired shape and dimensions such as a predetermined grindstone, cutting tip, and sliding material.

(Problems to be Solved by the Invention) However, since the conventional CBN composite molding pair uses blocky CBN particles, the orientation of the CBN particles is random, and on the surface of the chip that comes into contact with the workpiece, CB
The flat surface of the N particles is exposed, as well as the edges. Since the sharpness of CBN is originally provided by the sharp edges of the CBN particles, the conventional CBN composite molded article having a random orientation is poor in sharpness, and the good sharpness of CBN is not sufficiently obtained.

Also, in the case of grinding stones, if blocky CBN particles are used, if the particles are cut to about 2/3 of their diameter, the particles will fall off, and the life of the grinding stone will be short, and the dropped particles Will scrape off the binder in the grindstone and accelerate the shedding of CBN particles. Similarly, when attempting to use a conventional blocky CBN composite molded article as an abrasion resistant mechanical material, the problem due to CBN falling off is serious.

Also, in the case of a conventional blocky CBN, when the molded body is used as a sliding material, the contact surface with the mating member will be point contact or line contact with the CBN, the contact area with the CBN will be reduced, and the wear of the binder will be reduced. As a result, there is a disadvantage that CBN protrudes and a grinding action occurs, in addition to increasing accuracy.

When CBN is used as a work rest of a centerless blade, the work material rotates at a high speed and generates high heat. However, a blocky CBN has poor heat dissipation. This applies to the case where the heat dissipation board is used.

The present invention provides a composite molded body that controls the orientation of CBN, which was not possible in the past, and can sufficiently bring out the original excellent performance of CBN, such as sharpness, abrasion resistance, and heat dissipation. With the goal.

(Means for Solving the Problems) According to the present invention, there is provided a CBN composite molded article comprising plate-like CBN particles and a binder, wherein the CBN particles are oriented in a certain direction.

As described above, the conventional CBN had a blocky particle shape. However, in Patent Application No. 1-51878, the present inventors disclosed a C source (for example, stearic acid, palmitic acid, docosan, terphenyl, melamine). A layer containing a hexagonal crystal to which urea, carbon, carbon black, B ₄ C, etc. are added, and a layer containing a CBN synthesis catalyst are laminated and subjected to a high-temperature and high-pressure treatment. Hexagonal plate-shaped CB with large ratio, preferably 2 to 20
It was proposed to manufacture N (consisting of {111} planes). The present invention has been completed by finding that such a plate-shaped CBN can be arranged in a certain direction when it is formed using a binder.

Here, the orientation means that the plate surface of the plate-shaped CBN has a clear directionality. Specifically, either the surface of a cube or a rectangular parallelepiped (composite molded body) is parallel to the flat main surface of CBN;
As an example of the orientation, flat main surfaces of CBN are parallel; CBN is arranged in a circumferential direction in a ring (composite molded body). Quantitatively expressing the directionality, it means that the statistical distribution in the direction perpendicular to the CBN main surface falls within about ± 30 ° at 2σ.

 The following can be used as the binder.

Metal: Al, Ti, Ta, W, Zr, Mo, Nb, Zn, Si, Ni, Co, Fe, Cr, Mn, C
One or more of u and Sn Ceramics: One or more of TiC, TiN, WC, TaC, TaN, Si ₃ N ₄ and Al ₂ O ₃ (Al, Ni, C
o, Fe, Mn, one or more of them) Organic polymer: phenolic resin, polyimide resin, bakelite resin, etc. Glass: borosilicate glass, boric acid glass, etc. Metal is 80 ~ 90vol%
Preferably, the ceramic is preferably 25 to 50 vol%, the organic polymer is preferably 50 to 70 vol%, and the glass is preferably 10 to 60 vol%.

Hereinafter, the composite molded article of the present invention will be described in detail by embodiments.

First, an embodiment in which a metal is used as a binder to form a grinding wheel segment, a sliding material, and a semiconductor substrate will be described.

When manufacturing CBN metal whetstone segments, plate-shaped C
When BN 10 to 20 vol% is mixed with a Cu-Sn-based metal powder as a binding metal and molded at a pressure of about 5 ton / cm ² , the plate-shaped CBN which has been oriented in a random direction at the time of mixing, Orientation almost vertically. Thereafter, a heat treatment is performed at a temperature of 750 ° C. to 800 ° C. to bond the binder powders together and the binder and the CBN firmly, and then cut them into a predetermined size to form a grindstone segment.

When manufacturing a sliding material, plate-like CBN is first placed in a molding die and vibrated. The amount of CBN to be put into the mold should be at least as long as plate-shaped CBNs are arranged in the cross-sectional area of the mold with as little space as possible, and preferably 2 to 10 layers of CBN are laminated. Furthermore, as a binding metal, for example, 40
When 10 to 20 vol% of a Cu-Sn-based powder having a size of μm or less is put in a mold and further vibrated, the bonding metal enters the gap between the plate-shaped CBNs. Thereafter, by performing molding at a pressure of, for example, 5 ton / cm ² , the plate-shaped CBN at the lower end of the mold is oriented substantially perpendicular to the pressure axis along the lower end surface of the mold. After this 75
Heat treatment is performed at a temperature of 0 ° C. to 800 ° C., cut into a predetermined size, and finished to be a sliding material. In addition, since the plate-shaped CBN is often present on the side in contact with the mold and the bonding metal is largely present on the opposite side, the former is preferably used as the sliding surface.

In the case of a CBN resin bond grindstone, after mixing 20 to 50 vol% of plate-like CBN with a phenol resin and a filler as a binder, heat molding is performed at a pressure of 500 to 700 kg / cm ² and a temperature of 180 to 200 ° C. Also in this case, the plate-shaped CBN which has been randomly oriented at the time of molding at the time of forming like the metal whetstone is oriented substantially perpendicular to the pressure axis direction.

For CBN vitrified bond grinding wheels, plate-like CBN 20 to 60
vitrified bond 10 ~ 40vol with vol% as binder
% And a filler of 0 to 20 vol% are molded at a molding pressure of 50 to 150 kg / cm ² , and then heat-treated at 800 to 1200 ° C. In this case as well, a plate shape that was oriented in the random direction at the time of molding
CBN is oriented almost perpendicular to the direction of the pressure axis.

FIG. 1 is a conceptual view of a composite molded body manufactured in the above-described direction, and FIG. 2 is a diagram showing that the composite molded body is fixed to a grinding wheel. In the figure, 1 is a composite molded body, 2 is a plate-shaped CB
N, 3 indicate a bonding material, 4 indicates a grinding wheel segment, and 5 indicates a wheel support. Fig. 2 shows a plate-shaped parallel to the direction of the arrow.
When the plane of CBN2 is oriented, CBN is always cut into the workpiece at the edge. In addition to the binder, in the case of an organic polymer as a filler, C, Ag, Cu, BN, Al ₂ O ₃ , SiC, etc., glass, Al ₂ O ₃ , SiC, etc., in the case of metal, C, hard ceramic, etc. Can be added. However, if the amount of the filler is increased, the strength of the molded body is reduced. Therefore, it is preferable to set the addition amount to 10 vol% or less.

In the case of a CBN cutting tip, 50 to 75 wt% of plate-like CBN and 25 to 50 wt% of Al and Tic, TiN as binders are mixed and tentatively formed. At this time, the plate-shaped CBN oriented in the random direction is oriented almost perpendicular to the pressure axis. Thereafter, when sintering is performed at a pressure of 20 to 60 Kbar and a temperature of 1000 ° C. to 1500 ° C. using an ultra-high pressure apparatus, the orientation of the plate-like CBN becomes more complete. The obtained sintered body is processed to a predetermined size by an electric discharge machine or the like and finished to obtain a cutting tip 7 (FIG. 3). This is fixed to 6 such as steel to form a cutting tool.

In addition, as a method of orienting the plate-shaped CBN, after dispersing the plate-shaped CBN in the bonding metal and then rolling, or after dispersing the CBN on the plate in the paste and then applying and orienting it by applying There are methods such as baking.

In the case of CBN particles having a fairly large plate-like ratio, the CBN particles can be oriented by applying to a substrate together with a liquid binder having an appropriate viscosity, such as α-tvneol.
In this case, if the viscosity is too low, the CBN will be oriented in a random direction, and if the viscosity is too high, the binder will not spread easily, and in either case, the desired orientation will not occur.

There are various orientation methods, but any method may be selected as long as the orientation can be matched to the intended use of the molded article.

An embodiment in which the plate-like CBN is oriented by roll forming will be described with reference to FIG. In the figure, 8 is a roll, 9
Is a material such as a plate or a rod in which a plate-shaped CBN and a binder are preformed. As a binder, a flexible material such as a resin or a Cu-Sn alloy is used, and when the plate 9 is roll-formed many times, the flat surface of the plate-shaped CBN grains gradually becomes parallel to the surface of the plate 9. And the orientation proceeds. Thereafter, heat treatment for curing or reacting the binder is performed, and if necessary, the material 9 is bent,
Cut and finish.

(Function) When a composite compact whose orientation is controlled by plate-shaped CBN is used for grinding and cutting, the plate-shaped CBN used has sharper edges than conventional blocky grains. Because it is facing, cutting is improved.

For example, when plate-shaped CBN having an average particle diameter of 200 μm and a plate-shaped ratio of 5 is used, the actual contact with the workpiece is the same as the contact with sharp CBN particles of size ^# 325. , The sharpness is improved, while the CBN is supported by the binder on the plate surface, the life is equivalent to that of coarse particles of about ^# 60 supported by the binder, the support is strong and the life is long Is achieved. As shown in this example, plate-like CB
Orienting N increases the life and cuts.

Also, in wear-resistant mechanical materials, since the plate surface of CBN faces the mating material, the abrasion effect of the mating material is received by the plate surface of CBN, and it is stronger against abrasion. Since the edge does not face the mating material, the mating material does not wear.

Further, in a semiconductor heat dissipation board, the area of CBN receiving heat generated by the semiconductor increases, and the heat dissipation effect increases.

 Hereinafter, the present invention will be described in more detail with reference to examples.

(Example) Example 1 15 vol% of plate-like CBN having an average particle diameter of 200 µm and a plate-like ratio of 5 and 85 vol% of a Cu-20% Sn alloy powder as a bonding metal were mixed. This mixed powder is molded at 5 ton / cm ² and 30mm (l) x 3mm
(W) × 5 mm (t), arc shape of 75 mm (radius of curvature (R)), and heat treatment was performed at 750 ° C. The obtained composite molded body is cut by a diamond cutting blade,
When the orientation state of CBN was observed with a scanning electron microscope,
The plate-like CBN was oriented almost perpendicular to the pressing axis. A grindstone was produced using this composite molded body (A). For comparison, normal CBN abrasive grains (SBN-T, particle size ^# 32, manufactured by Showa Denko KK)
A metal-bonded grindstone was obtained in the same manner using (5) (B).

When the grinding wheels A and B were subjected to a surface grinding test under the following conditions, the results shown in Table 1 were obtained.

Grinding wheel peripheral speed 1500m / min Work SKH-51 (H _R C62) Depth of cut 40μ Table speed 15m / min Method Plunge method Grinding fluid Soluble type The grinding power and the grinding length are relative values when the comparative example is set to 100 (the same applies hereinafter).

From the above table, it can be said that the grindstone A of the present invention has a good cutting performance and a long life.

Example 2 60% metal in plate-shaped CBN with an average particle size of 200 μm and a plate ratio of 5
42 vol% of coated abrasive grains, 48 vol% of phenol resin as binder, filler material (WA, Showa Denko, particle size ^# 22
0) 10 vol% and mixed, molding pressure 500~700Kg / cm ^2, temperature 18
Performs heat molding at 0 to 200 ° C and measures 30 mm (l) x 3 mm
(W) × 5 mm (t), an arc-shaped composite molded body of 75 mm (radius of curvature (R)) was obtained. When the obtained composite molded body was cut and the internal CBN orientation state was observed with a scanning electron microscope,
The plate-like CBN was oriented almost perpendicular to the pressing axis. A grindstone (C) of the present invention using this composite molded body was manufactured.
For comparison, a regular CBN grinding stone (SBN-DN manufactured by Showa Denko
Resin bond grindstone (D) produced in the same manner using particle size ^# 325) was obtained.

When these wheels were subjected to a surface grinding test under the following conditions, the results shown in Table 2 were obtained.

Grinding wheel peripheral speed 1500m / min Work SKH-51 (H _R C62) Depth of cut 40μ Table speed 15m / min Method Plunge method Grinding fluid Soluble type From the above table, it can be said that the grindstone C of the present invention has a good cutting performance and a long life.

Example 3 After forming 40 vol% of plate-like CBN having an average particle diameter of 200 μm and a plate-like ratio of 5, 25 vol% of a vitrified bond as a binder, and 5 vol% of a filler (manufactured by Showa Denko KK, wA ^# 220) at a molding pressure of 100 kg / cm ² , Heat-treated at 1000 ° C for a bite stone segment with 30 vol% pores (dimensions 30mm (l) x 3mm (w) x 5mm
(T), 75 mm (radius of curvature (R)). Observation of the internal state with a scanning electron microscope revealed that the plate-like CBN was oriented almost perpendicular to the pressing axis.

A grindstone (E) of the present invention using this composite molded body was produced. For comparison, a similar vitrified grinding wheel (F) was obtained using the above-mentioned ordinary CBN abrasive grains (viscosity ^# 325).

When a surface grinding test was performed on these whetstones under the following conditions, the inspections shown in Table 3 were obtained.

Grinding wheel peripheral speed 1500m / min Work SKH-51 (HRc62) Depth of cut 40μ Table speed 15m / min Method Plunge method Grinding fluid Soluble type From the above table, it can be said that the grindstone E of the present invention has a good cutting performance and a long life.

Example 4 Plate-shaped CBN having an average particle diameter of 50 μm and a plate-shaped ratio of 60 wt%; TiC powder having an average particle diameter of 2 μm as a binder, 30 wt%, Al ₂ O ₃ powder having an average particle diameter of 0.6 μm as 10 wt%, and an average particle 20μm diameter Al powder
Temporary molding was performed by mixing with 10 wt%. The temporarily formed raw material plate was placed on a WC sintered substrate, and a plurality of the raw material plates were put in a Zr cup, and a salt (NaCl) plate was put between them and laminated. And Zr
The cup was placed in a graphite cylindrical heater, and the space between the Zr cup and the heater was filled with NaCl. The assembly assembled in this manner was set in an ultra-high pressure apparatus and held at 1300 ° C. and a high temperature and pressure of 40 Kbar for 30 minutes to sinter the raw material plate. This sintered raw plate becomes a CBN sintered body.

Cut the obtained sintered body with a diamond cutting blade,
When the internal state was observed with a scanning electron microscope,
CBN was oriented almost perpendicular to the pressing axis.

The above sintered body was processed into a cutting tip (G), and the cutting speed was 100 m / min using SNCM-439 having a hardness of H _R C52 as a work material.
When a cutting test was performed with a feed of 0.1 mm / rev and a depth of cut of 0.5 mm, the results shown in the following table were obtained. Normal CB as a comparative example
The same trial was performed with a cutting tip (H) made of a sintered body using N. The life was based on the time to reach V _B = 0.2 mm.

From the above table, it can be seen that the cutting insert according to the present invention has a long life.

Example 6 A plate-like CBN having an average particle size of 750 μm and a plate-like ratio of 5 was placed in a molding die, and vibration was applied using a vibrator to arrange the plate-like CBN on the lower end surface of the die without any gap. Repeat this operation,
After stacking 5 layers, Cu-20% Sn is added as a bonding metal, and
/ cm ² was molded. Thereafter, heat treatment is performed at 750 ° C. Cutting the obtained molded body with a diamond cutting blade,
The internal state was observed with a scanning electron microscope.
N was oriented almost perpendicular to the pressure axis.

The surface of the molded body was finished, and the coefficient of friction between the molded body and SUS304 was measured. The measurement was performed with a sliding surface pressure of 6 kg / cm ² and a peripheral speed of 0.2 m / cm.
The measurement was performed in water (17 ° C.). As a result, the friction coefficient is 0.0
Good sliding characteristics of 15 were obtained.

(Effects of the Invention) As described above, according to the present invention, while controlling the orientation of the plate-shaped CBN and using the composite molded body so that the edge is constantly in contact with the work, the cutting performance is improved, and Sustained and long-life grinding wheels and cutting tips can be provided.

Also, CBN itself has abrasion resistance, but easily damages the mating material, but if the mating material slides on the flat surface of the plate-shaped CBN, the latter property will not appear Thus, the CBN composite molded body can be used as a wear-resistant mechanical part.

Furthermore, the heat dissipation effect as a semiconductor heat dissipation board can be enhanced.

[Brief description of the drawings]

FIG. 1 is a conceptual view of a composite molded body, FIG. 2 is a view showing that the composite molded body is fixed to a grinding wheel, FIG. 3 is a view of a cutting tip, and FIG. It is explanatory drawing of the embodiment which makes it orientate. In the drawing, 1 ... composite molded body, 2 ... plate-like CBN, 3 ... bonding material, 4 ... grinding wheel segment, 5 ... wheel support, 7
… Roll, 8 …… Preformed material of plate-shaped CBN and binder

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ identification symbol FI C09K 3/14 550 C09K 3/14 550C C22C 29/16 C22C 29/16 A (58) Investigation field (Int.Cl. ⁶ , (DB name) C04B 35/5831 C22C 29/16 B24D 3/00 310 B24D 3/00 320 C09K 3/14 550 C08L 101/00

Claims (1)

(57) [Claims] 1. A cubic boron nitride oriented compact comprising plate-like cubic boron nitride particles and a binder, wherein the cubic boron nitride particles are oriented in a certain direction.