JPS61297079A - Covered highly hard powder and manufacture thereof and grindstone made of said powder as main component - Google Patents

Abstract

PURPOSE:To improve grinding performance and durability by forming the main component of a grindstone from the covered highly hard powder having a specific covered layer. CONSTITUTION:The surface of diamond powder and/or cubic boron nitride powder is covered with titanium carbide and/or titanium carbonate, and the covered highly hard powder is obtained. The durability of a resin bond grind stone containing the covered highly hard powder as main component, and bonding agent and additives is improved as shown by O-marks, and the surface roughness (Rmax) is 6mum.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a coated highly hard powder, a method for producing the same, and a grindstone containing the powder as a main component. The present invention relates to a coated highly hard powder that becomes superabrasive grains suitable for machining, a method for producing the same, and a grindstone made using this coated highly hard powder.

[Technical background of the invention and its problems] In recent years, ceramic materials have attracted attention as new materials in various fields, such as tool materials, insulating materials for ICC boards, medical materials such as artificial bone roots, or,
Its importance is increasing as a material for various machines such as automobile engine parts.

By the way, since these ceramic materials 1 are hard and brittle materials, it is often impossible to use conventional tools when performing high-precision grinding, for example.

Therefore, when grinding hard and brittle materials such as ceramic materials, it is common to use a grindstone containing carbide abrasive grains such as diamond powder. Such a grindstone is manufactured by molding and firing a mixture of the carbide abrasive grains and particles of a metal oxide such as alumina (Al2O2) and a binder such as a resin or a glassy inorganic material. At this time, a grindstone using a resin as a binder is called a resin bond grindstone, and a grindstone using a glassy inorganic substance is called a vitrified bond grindstone.

In the case of resin pound whetstones whose main component is diamond powder, the surface of the powder is usually coated with a metal such as nickel (Ni) in order to increase the bonding strength between the powder and the resin that is the binder. There is. By applying the old coating in this manner, irregularities are formed on the surface of the diamond powder, thereby increasing the mechanical bonding force with the resin, and as a result, the powder retention power of the resin is improved. Furthermore, since Ni has low thermal conductivity, it has the advantage of preventing the resin from deteriorating due to the heat generated at the tips of the abrasive grains during use of the whetstone. however,
On the other hand, a problem arises in that the Ni coating layer causes clogging of the grindstone. , the surface of the diamond powder is also coated with Ti
A coated diamond powder coated with (CJI, O) is disclosed in JP-A-55-IEi2499.

However, this also still leaves room for improvement in terms of the adhesion of the film.

On the other hand, vitrified bond grindstones, which also have diamond powder as their main component, are manufactured by high-temperature firing, so
The bonding force between the abrasive grains and the binder is strong due to the solid phase reaction. However, there is a problem that thermal corrosion of the diamond occurs during the high-temperature firing process, making manufacturing difficult.

[Object of the invention] The present invention solves the conventional problems and provides a coated high-hardness powder used as abrasive grains for grinding wheels, which, when the binder is a resin, has a strong bonding force with the resin, and , a coated high-hardness powder that does not cause clogging of a grindstone due to the coating layer, and on the other hand, when the binder is a glassy inorganic material, heat corrosion of the powder itself does not occur during firing, a method for producing the same, and the powder The objective is to provide a whetstone that has excellent grinding performance.

[Summary of the Invention] As a result of intensive research to achieve the above two objects, the present inventors have discovered that the surface of diamond powder and/or cubic boron nitride powder is ) instead of titanium carbide (TiC) and/or titanium carbonate (Ti(
It was confirmed that the coated high-hardness powder coated with C,0)) has excellent properties as a carbide abrasive grain, and that the grinding wheel made of the powder as a main component also has excellent grinding performance. As a result, the present invention was completed.

That is, the coated high-hardness powder of the present invention is characterized by coating the surface of diamond powder and/or cubic boron nitride powder with titanium carbide and/or titanium carbonate, and the manufacturing method thereof includes Production of coated high-hardness powder in which the surface of diamond powder and/or cubic boron nitride powder is coated with titanium carbide and/or titanium carbonate by applying a vapor phase chemical growth method using titanium and hydrocarbon gas as reaction gases. A method in which the molar ratio of the titanium halide to the hydrocarbon gas is 1:3 to 1:9, and the reaction temperature is 800°C.
It is characterized by a temperature of ~1100°C.

Furthermore, the grinding wheel mainly composed of the coated high hard powder has a coated high hard powder formed by coating the surface of diamond powder and/or cubic boron nitride powder with titanium carbide and/or titanium carbonate; and a binder. and an additive.

First, in the coated high hardness powder of the present invention, the powder used is diamond powder or cubic boron nitride (CBN).
It is a powder or a mixture of these.

The type of diamond powder used is not particularly limited, and may be either natural or artificial.

In addition, the shape etc. are not particularly limited, but those with anisotropy in the crystal axis, for example, EMBS (1130/40
, de Pierce) or CDA (1180/100
．． De Pierce) etc. have a smaller thermal expansion coefficient than normal cuboctahedral ones, so they are coated with titanium carbide (TiC) or titanium carbonate (Ti(C)) in the process described below.
, 0)) is preferable in that cracks are less likely to occur in the film after the coating is formed. Furthermore, Ni, Fe,
Diamond, which contains a large amount of metal impurities such as Go, is preferable because it has high adhesion strength for TiC and/or Ti(C,0) coatings. The particle size of the diamond powder or CBN powder used as the grindstone is preferably about 10 to 50 μm.

On the other hand, the coating formed on the surface of the diamond and/or CBN powder is made of TiC and/or Ti(C,0). Ti(C,O) is produced when oxygen is mixed in depending on the reaction conditions during the TiC coating process using the CVD method described below, but it has high adhesion strength to the powder surface and has excellent properties as a film. It is something. In this case, it is desirable that the oxygen content be as low as possible.

The layer thickness of these TiC and/or Ti(C,0) coating layers is not particularly limited, but is usually 0.1 to 6-
It is preferable to set it to a certain degree.

Next, a method for manufacturing the coated highly hard powder of the present invention will be explained.

The coated high-hardness powder of the present invention is produced by applying chemical vapor deposition (CVD) to diamond and/or carbon as described above.
It is manufactured by coating the surface of BN powder with TiC and/or Ti(C,O). In addition to the above-mentioned CVD method, general thin film forming methods such as Pv method such as sputtering method and ion blating method can be applied to this coating process, but two points are important: mass productivity and film adhesion strength. Taking this into consideration, it is most preferable to apply the CVD method.

Processes performed by applying this CVD method, for example,
Tic coating proceeds by two reactions with the following formula: %Formula %.

The reaction conditions in this coating step are preferably set appropriately depending on the layer thickness of the TiC and/or Ti(,C,0) coating layer, etc., but considering the growth rate and adhesion of the coating layer, titanium halide and hydrocarbon gas at a molar ratio of 1:3 to 1:9, and a reaction temperature of 800 to 1100°.
Set to C. Furthermore, it is desirable to increase the partial pressure of the reactive gas such as CH4 in order to obtain a TiC film with high adhesion strength. The TiC film thus obtained has fine grained polycrystals and has extremely high adhesion strength.

Furthermore, when using diamond powder, this Ti
It is preferable to heat-treat the diamond powder at 900 to 1300° C. in vacuum prior to the C coating step, since this further improves the adhesion strength of the TiC film.

This is thought to be because internal impurities such as dirt precipitate on the surface of the diamond powder during the heat treatment process, and when such diamond powder is coated with TiC, the TiC film becomes whisker-like and the reliability strength is improved. In this coating process, by adjusting various conditions, TiC is first applied to the surface of the diamond powder.
A layer consisting of x (Ocxc:1) is formed, and then,
It is further advantageous to form a film in which the proportion of carbon changes continuously by coating with TiC in order to improve the adhesion of the film.

Next, the grindstone of the present invention, which contains the coated highly hard powder of the present invention as a main component, will be explained.

As mentioned above, the grindstone of the present invention has as the main component of the abrasive grains:
A coated high-hardness powder (Tie and/or Ti(C,0) coated diamond and/or CBN powder) is used, and this, a binder, and an additive are included as essential components. The binder is a component for binding and supporting abrasive grains and other components, and is mainly divided into two types, resins and glassy inorganic materials, although they are not particularly limited. Resin-pound whetstones that use thermosetting resins as binders, such as phenol resins, epoxy resins, and polyimide resins; whetstones that use vitreous inorganic materials such as borosilicate glass, lead glass, and sodium glass as binders. It is called a vitrified bond grindstone.

In the grindstone of the present invention, in addition to this, additives include:
Hollow carbon, carbon, Aj1203, ZrO2, S
Fillers such as iC, BaC, cryolite, and FeS (among others, containing ai2o3, ZrO2, SiC, and BaC makes dressing easier and prevents clogging); wetting agents such as furfural and water glass; quicklime, etc. Contains a water absorbing agent.

On the other hand, the grindstone of the present invention preferably contains a certain amount of pores. This is because the pores have the function of discharging chips generated during grinding and dissipating heat generated during grinding. The content of the pores, that is, the porosity is preferably about 20 to 35%.

The grindstone of the present invention is manufactured as follows.

That is, first, the above-mentioned components are mixed at a predetermined mixing ratio. Thereafter, it is molded into a predetermined shape by applying a conventional method such as a hot press method, a vacuum firing method, or an inert gas atmosphere firing method. Next, this molded body is fired to obtain the desired grindstone. The firing temperature in this case is 160 to 250°C for resin bonded whetstones, and needs to be determined according to the softening point of the binder for vitrified bonded whetstones. For example, for borosilicate glass, it is about 800°C, For high lead glass, it is preferable to set the temperature to about 500°C.

[Embodiments of the Invention] Example 1 (Production of Coated Highly Hard Powder) C [Abayashi 140/170 (Do-
Pierce Co.), and this powder was coated with TIC by applying the CVD method. Coating conditions are vacuum degree 88h+wHg
First, the temperature was raised to 1050°C at a heating rate of 8.75'O/win with H2: 2fL and CH4: 0.03cm. Next, this temperature smell, H2 (Tit44)
: 21, H2: IJl, CH4: 20 in 0.3 sentences
After coating was performed by holding for a minute, the temperature was lowered. The average thickness of this TiC coating was 3 units.

When the surface of the TiC-coated diamond powder obtained in this way was observed by SEH, it was confirmed that the TiC coating was fine-grained polycrystalline and had extremely high adhesion strength.

Example 2 (Production of Coated Highly Hard Powder) A TiC-coated diamond powder was produced in the same manner as in Example 1 above, except that the coating conditions were changed as follows.

Reaction conditions: ■H2:C)14=ll18.5:1.5(
Volume ratio) Temperature raised to 1050°C in atmosphere ■ H2: TiC text 4 = 9 fl: 4 (volume ratio) atmosphere, 1
Hold at 050°C for 5 minutes ■ H2: TiC standing 4: CH4 = 78:4:20 (volume ratio) atmosphere, hold at 1050°C for 20 minutes ■ Cool in H2 Cut the TiC-coated diamond powder thus obtained When the surface was observed by SEM, it was found that a 0.5-thick T1Co 7 film was formed on the diamond powder surface, and a 0.5-thick TiC film was further formed on the outer periphery of the diamond powder. Near the interface, the stoichiometric ratio of C is 0.
It was confirmed that the number changed continuously from 7 to 1. The adhesion strength of this film was also extremely high.

Example 3 (Production of Grindstone) A resin bonded grindstone having the following composition 4 was produced using the TiC-coated diamond powder obtained in Example 1 as the main abrasive component.

TiC coated diamond powder 4gA203
(Showa Denko Co., Ltd.: Particle Size Cloud 120) After mixing each component of 2.9 tt or more, for example, by applying a hot press method, at a temperature of 170 ± 5 ° C., an outer diameter of 125 m φ,
A molded body having an inner diameter of 50.8 layers and a thickness of 12 mm was obtained.

Thereafter, the molded body was heated at a temperature increase rate of 17°C/h,
After holding at 170℃ for 10 hours, the cooling rate was 17℃/
The resulting product was fired by cooling at 100 ms to obtain a remade bond grindstone of the present invention.

The thus obtained resinoid pound grindstone had a porosity of 25% and a bending strength of 24 kg/as2. Regarding this resinoid pound whetstone, it is actually ai2o3, S
Grinding of i3N4 and SiC was performed and the following items were evaluated.

(1) Surface roughness of the ground surface Rm
ag) was measured and the results are shown in Table 1.

Table 1 (2) Durability of grinding wheel Wave force ■ As the workpiece, Si3N4 of too intestinal At this time, the amount of wear on the outer periphery of the grindstone was measured with an electric micrometer for every 1000-degree cut, and the results are shown as 0 marks in FIG. Note that the surface roughness (Rmag) of the workpiece after the grinding process was 6μ.

Comparative Example 1 A resin-bonded grindstone was manufactured in the same manner as in Example 3 above, except that uncoated diamond powder was used instead of coated diamond powder, and the same evaluation test was conducted. The results are shown in Table 1 and Figure 1. Indicated with a mark. The surface roughness (R amount a) of the Si3N4 workpiece after finishing the grinding process with a depth of cut of 5000 was 11111M, and the surface smoothness was considerably inferior to that of Example 3.

Example 4 (Manufacture of grindstone) A vitrified bond grindstone having the following composition was manufactured using the TiC-coated diamond powder obtained in Example 1 as the main abrasive grain component.

TiC coated diamond powder 4.2gA 2
03 (Showa Denko 2-grain size cloud 120) 1.9 tt
(Crushed and adjusted particle size to @240) Wetting agent: Water glass 0.8 First, add a small amount of water glass to the weighed abrasive grains with a dropper, wet the entire abrasive grains, and then add a binder. Mix thoroughly. Then, using a mold with a predetermined shape, the appropriately moistened raw material was put into the mold and pressure-molded. At this time, the molding pressure was 2 kgf/■12,
The holding time was 3 minutes. Thereafter, the obtained molded body was heated at a heating rate of 290° C./win at 800° C. in a hydrogen atmosphere.
Baked at ℃ for about 1 hour, 20m × 50 pieces × 5m
■ Obtained a whetstone. Note that the firing temperature of a normal vitrified bond grindstone is 1200 to 1300°C, but in this example, the above 8
Firing was performed at a low temperature of 00°C.

The vitrified bond grindstone thus obtained had a porosity of 30% and a bending strength of 1.7 kgf/mm2.

Using this vitrified bond grindstone, evaluation tests (1) and (2) similar to those in Example 3 described in -1- were conducted, and the results are shown in Table 2 for test (1) and for test (2). are respectively indicated by Δ marks in FIG.

Table 2 Note that the surface roughness after grinding in evaluation test (2) was 8 μm.

Comparative Example 2 A vitrified bond grinding wheel was produced in the same manner as in Example 4 above, except that uncoated diamond powder was used as the diamond powder, and the same evaluation test was conducted. The results are shown in Table 2 and Figure 2. Indicated with a mark. The surface roughness (Rmag) of the Si3N4 workpiece after finishing the grinding step with a depth of cut of 5000- was 13μ, and the surface smoothness was considerably inferior to that of Example 4.

Example 5 TiC coated CBN instead of TiC coated diamond powder
Powder (Showa Denko 5BN-T Ken140/170)
A vitrified bond grindstone was produced in exactly the same manner as in Example 4, except that 4.3 g of TiC coating was applied in the same manner as in Example 1. The obtained grindstone was subjected to the same evaluation tests as above, and as a result, the same good results as above were obtained for both the surface roughness of the grinding surface of the workpiece and the durability of the grindstone.

[Effects of the Invention] As is clear from the above description, the grinding wheel of the present invention is mainly composed of the coated high-hardness powder of the present invention, that is, the Tie and/or Ti(C,0) coated diamond and/or CBN powder. It was confirmed that both resin pound and vitrified bond types have excellent grinding performance and durability. This is because the TiC and/or Ti(C,
O) This is due to the extremely high bonding strength between the coated diamond and/or CBN powder and the binder. Moreover, in the coated high hardness powder of the present invention, TiC and/or T
The adhesion strength of the i(C,0) film is higher than that of the conventional 1 or Ti(J
Since it is higher than that of a coating made of N, 0), clogging of the grindstone due to peeling of the coating does not occur at all. Furthermore, in the case of a vitrified bond grindstone using the coated powder, it can be fired at a low temperature of 800 to 800°C, thereby preventing the occurrence of hot corrosion of diamond. Therefore, its industrial value is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the grinding characteristics of a resin bond grindstone according to one embodiment of the present invention, and FIG. 2 is a diagram showing the grinding characteristics of a vitrified bond grindstone according to another embodiment of the invention.

Claims (1)

[Claims] 1. A coated high-hardness powder characterized in that the surface of diamond powder and/or cubic boron nitride powder is coated with titanium carbide and/or titanium carbonate. 2. Coating height in which the surface of diamond powder and/or cubic boron nitride powder is coated with titanium carbide and/or titanium carbonate by applying a vapor phase chemical growth method using titanium halide and hydrocarbon gas as reaction gases. A method for producing a hard powder, the molar ratio of the titanium halide and hydrocarbon gas being 1:3 to 1:3.
1:9, and the reaction temperature is 800 to 1100°C. 3. It is characterized by containing a highly hard coated powder obtained by coating the surface of diamond powder and/or cubic boron nitride powder with titanium carbide and/or titanium carbonate; a binder; and an additive. Whetstone. 4. The grindstone according to claim 3, wherein the binder is made of a vitreous inorganic substance. 5. The grindstone according to claim 3, wherein the binder is a thermosetting resin.