JP3295574B2 - Two-layer metal plated diamond fine particles and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-layer metal-plated diamond fine particle in which W and a Ni--P alloy are applied to a lower layer and an upper layer, respectively, and a method for producing the same.

[0002]

2. Description of the Related Art Diamond particles are used for various diamond tools such as cutting tools,
It is used for materials such as drilling tools and dressers. In order to manufacture this diamond tool, it is necessary to mold by bonding diamond particles. This bonding is performed by a resin bond method, a metal bond method, an electrodeposition method, a vitrified method, or the like.

[0003] However, simply forming the as-produced diamond with a binder through these methods has a disadvantage that the diamond particles are easily deteriorated or peeled off. For example, when manufacturing a diamond wheel using a Ni powder as a binder by a metal bond method, diamond particles and Ni powder are mixed, molded into a wheel, and then fired at about 1,100 ° C. However, if the diamond particles are heated to 600 ° C. or higher, they tend to be graphitized, and there is a difference in thermal expansion between diamond and Ni. It is easy to peel off from the binder and reduces the cutting performance of the grindstone.

[0004] Therefore, in order to improve these disadvantages, various surface treatment methods have been conventionally proposed. For example,
Cu, Cr,
Single-layer plating of metal or alloy such as Mn, Ta, Ni-P or the like (JP-A-49-59388, JP-A-63-59388)
JP-A-190756), and a method of suppressing the graphitization and thermal stress by concealing the surface of diamond particles by applying a single-layer plating of a metal such as Au, Ag, Cu or the like (JP-A-49-49286). is there.

[0005] However, even if the surface of the diamond particles is concealed with a metal or an alloy by these methods, the graphitization of the diamond particles and suppression of thermal stress have been insufficient. This is because the entire surface of the diamond particles is not always completely plated by electroless plating, and the adhesion between the plating layer and the diamond particles is not always strong.
It is presumed that the atmosphere gas entered the interface between the plating layer and the diamond particles during sintering.

Another cause is that a part of the plating solution component is adsorbed on the plating layer formed by the electroless plating method, so that it decomposes at the time of sintering, and the component is removed from the surface of the diamond particles. It is considered that the diffusion of the atmospheric gas into the plating layer and the diffusion of diamond particle carbon into the plating layer occur during sintering, thereby causing the graphitization of the diamond particles and thermal stress.

As a method of solving the problem of the coating by the electroless plating method, it is conceivable to apply the coating by the CVD method. However, in order to coat the diamond particles with a metal or an alloy by the CVD method, the diamond particles must be coated. Since it is necessary to form a lump, it is difficult to form a uniform plating layer on the surface of each diamond particle. Also, C
In order to secure the adhesion of the plating layer by the VD method, the diamond particles must be kept at a high temperature of 600 to 1.000 ° C. during vapor deposition, so that the diamond particles may be graphitized or thermally decomposed during the reaction. .

In recent years, diamond tools for high-precision machining are required, and accordingly, diamond particles are required to be fine particles having a particle size of 0.1 to 10 μm. Since it is extremely easy to agglomerate and cannot be monodispersed one by one, it has not been possible to apply uniform and good adhesion to each of such fine particles by electroless plating or CVD. In particular, in the case of the electroless plating method, a pretreatment such as a sensitivity treatment or an activation treatment is individually required for the diamond fine particles, but it is technically extremely difficult to uniformly apply such a pretreatment to each fine particle. Met.

[0009]

SUMMARY OF THE INVENTION In view of the above, the present invention provides a metal-plated diamond fine particle excellent in graphitization resistance and heat stress resistance, and a production method without thermal decomposition.

[0010]

According to the present invention, a metal-plated diamond fine particle is formed as a first layer on the surface of a diamond fine particle having a particle size of 0.1 to 10 μm by a sputtering method. After the plating, the Ni-P alloy plating having a weight of 20 to 50 mass% after plating was applied on the first layer as a second layer by an electroless plating method, and the production was sealed. The diamond fine particles are accommodated in a rotating drum, W-plating is applied to the diamond fine particles by a sputtering method while flowing the diamond fine particles by rotation of the rotating drum, and then Ni-P alloy plating is performed by an electroless plating method in an aqueous solution. It was done by doing.

[0011]

The present inventors have conducted various studies to improve the graphite resistance and the thermal stress resistance of metal-plated diamond fine particles obtained by plating a metal or alloy on the surface. As a result, after performing W plating by the sputtering method, Ni by electroless plating
-P alloy plating improves graphite resistance and heat stress resistance, and diamond particles hardly aggregate when the atmosphere is evacuated. Therefore, the sputtering method is used while flowing the diamond particles in a rotating drum. It has been found that if W plating is performed, even fine particles can be uniformly plated with good adhesion to individual particles, and the present invention has been completed.

The fine diamond particles to be metal-plated in the present invention may be any of natural and artificial diamonds.
μm. Particles having a particle size of 0.1 μm or less are not commercially available at present and are difficult to obtain.

The plating layer of diamond fine particles has a two-layer structure in which W plating is applied as a first layer (lower layer) and Ni-P alloy plating is applied thereon as a second layer (upper layer). The first layer is W-plated because it has the lowest coefficient of thermal expansion among metals and exhibits characteristics close to that of diamond, and does not generate thermal stress at the interface between diamond and the plating layer even when subjected to thermal history. , W is excellent in heat resistance and can cover the entire surface of diamond fine particles with a continuous thin plating layer. Therefore, diamond fine particles due to heat treatment such as sintering when producing diamond tools and frictional heat generated when cutting materials with tools. To be graphitized and oxidatively depleted, and to be extremely effective in preventing exfoliation during heating of a Ni-P alloy plating layer whose coefficient of thermal expansion is significantly different from that of diamond. That. The reason why the W plating is performed by the sputtering method is that the plating can be performed at a relatively low temperature of room temperature to 300 ° C., and that WC is formed at the interface with diamond and adheres firmly to diamond fine particles.

[0014] The amount of W plating is 1 to 1% of the weight after plating.
10 mass%, that is, [(W plating weight) / (diamond weight + W plating weight)] is 1 to 10 mass%. This is because if the amount is less than 1 mass%, the entire surface of the diamond fine particles cannot be covered with a continuous thin plating layer. On the other hand, W plating can cover the entire surface of the diamond particles with a sufficiently continuous plating layer of 10 mass% or less, so that it is not necessary to make the content larger than 10 mass%.

In the case of Ni-P alloy plating, the adhesion amount is 20 to 50 mass% of the weight after plating, that is, [(Ni-P alloy plating weight) / (diamond weight + W plating weight + N
i-P alloy plating weight)] is set to 20 to 50 mass%.
If this is less than 20 mass%, it is difficult to cover the entire surface of the diamond fine particles with a continuous thin plating layer, and if it is more than 50 mass%, the entire surface of the diamond particles is covered with a sufficiently continuous plating layer of 50 mass% or less. Because it doesn't need to be more.

[0016] Since W plating by the sputtering method is expensive in plating, it is desirable to minimize the cost.
The sum of W plating and Ni-P alloy plating is Ni-P
It is desirable that the weight after plating be 50 mass% or less.

In order to apply the first layer W plating to the entire diamond fine particles by sputtering, the diamond fine particles are put in a rotary drum, sealed, and then, while the diamond fine particles are rotated by rotating the rotary drum, W is removed. Sputter. Sputtering of W can be performed as long as the temperature of the diamond fine particles is in the range of room temperature to 300 ° C., so that the diamond fine particles are not deteriorated during sputtering. In order to apply W plating while flowing diamond fine particles in a rotating drum, various apparatuses have been developed so far, which may be used. For example, with a fine particle sputtering apparatus developed by the present inventors, as shown in JP-A-2-153068, a type in which a fluidized bed of diamond fine particles is formed in a rotating container and W is sputtered, Showa 6
As disclosed in Japanese Patent Application Laid-Open No. 2-250172, there is a method in which a falling flow of diamond fine particles is formed in a rotating container and W is sputtered.

The Ni-P alloy plating of the second layer may be activated by pretreatment, and then Ni-P alloy plating may be performed by electroless plating. In the pretreatment, first, the W-plated diamond particles are treated with an aqueous solution of stannous chloride,
Stannous chloride is deposited on the surface, and then treated with an aqueous solution of palladium chloride to deposit palladium metal, which is a catalyst for electroless Ni-P alloy plating, on the reduction of palladium chloride with the deposited stannous chloride. Activate.

In the electroless Ni-P alloy plating, the diamond fine particles pretreated as described above may be immersed in a mixed aqueous solution of a Ni salt and a hypophosphite and held for a predetermined time. Here, nickel chloride, nickel sulfate or the like may be used as the Ni salt, and sodium hypophosphite may be used as the hypophosphite. Ni-P alloy plating by electroless plating varies the P content depending on the plating conditions such as bath temperature, pH, concentration, etc., and changes mechanical properties such as hardness and ductility. Select plating conditions.

For example, when the P content is desired to be 3 to 5 mass%, an ammonia alkaline bath is used, and the P content is 6 to 12 mass%.
%, An acidic bath may be used, and if it is desired to be 10-15 mass%, a caustic alkaline bath may be used. Ni-
In general, a P alloy becomes harder with an increase in the P content, and its tensile strength increases, and becomes 350 kg / mm ^{2 in} the case of a plating layer using an ammonia alkaline bath, and 500 kg / mm ² in the case of a plating layer from an acidic bath. . However, in the case of a plated layer of diamond fine particles, a certain degree of ductility is required, and the mechanical properties change suddenly from a P content of about 7 mass%, so that 5 to 6 mass% is suitable. In addition, Ni-
After the P alloy plating, heat treatment may be performed as necessary to increase the hardness, adhesion, and the like of the plating layer.

[0021]

【Example】

(1) Sputtering plating of W Artificial diamond fine particles [manufactured by Tomei Diamond Industry Co., Ltd.
Trade name: IRM 0/3, particle size distribution: 0.1 to 10μ
m, average particle size: 1.5 μm]. In the apparatus shown in FIG. 1, a rotating drum 1 (inner diameter 200 mm, axial length 200 mm) is supported by two rolls 2, and one of the rolls 2 is rotated by a motor 3. Has become. Inside the rotating drum 1, two W sputtering sources 4 (frequency: 13.56 MHz, output: 1.5 KW
Magnetron type, the target is 99.9 mass% W
Plate) is placed, and the charged diamond fine particles 5
Can be plated with W.

Above the rotary drum 1, a decompression processing chamber 7 having a heating coil 6 on the outer periphery is arranged, and the bottom is connected to the rotary drum 1 by a supply pipe 9 having a valve 8. An Ar gas introduction pipe 10 is inserted into a portion of the supply pipe 9 below the valve 8 to form a double pipe.
The rotating drum 1 is inserted into the inside of the rotating drum 1 from the side, and the tip extends to the bottom of the rotating drum 1. A branch pipe 11 is provided below the valve 8 of the supply pipe 9, and the tip of the branch pipe 11 is connected to a fluid jet mill 12. Further, the outlet side of the fluid jet mill 12 is connected to the upper part of the decompression processing chamber 7 through the circulation pipe 13. Valves 14 and 15 are inserted in the branch pipe 11 and the circulation pipe 13, and a vacuum gauge 16 is connected to the circulation pipe 13.

In this apparatus, 100 g of the diamond fine particles 5 were put into the rotating drum 1 and the decompression processing chamber 7 was set to 3.0 ×
After reducing the pressure to 10 ⁻³ Pa, Ar gas was introduced through the Ar gas introduction pipe 10.
By introducing gas, the diamond fine particles 5 are split into branch pipes 11,
The liquid was suction-transferred to the decompression processing chamber 7 via the fluid jet mill 12 and the circulation pipe 13. Then, at 200 ° C.
For 30 minutes, dried and degassed. Next, after completely replacing the atmosphere of the rotating drum 1 with Ar gas, the diamond fine particles in the decompression processing chamber 7 are supplied from the supply pipe 9 to the rotating drum 1.
The sputtering was performed by the sputtering source 4 under a reduced pressure of 3.0 × 10 ⁻¹ Pa while rotating the rotary drum 1 at a rotation speed of 5 rpm.

After 10 minutes, the sputtering is stopped, the pressure in the vacuum processing chamber 7 is reduced, and the Ar gas introducing pipe 10 is removed.
, And the diamond fine particles 5 were sucked and returned to the decompression processing chamber 7 via the fluid jet mill 12 to loosen the diamond fine particles 5 which had become a lump during sputtering. The diamond fine particles returned to the reduced pressure processing chamber 7 had been subjected to W plating of 0.1 mass% of the weight after plating. When this operation was repeated five times, the W plating became 0.5 mass%. Therefore, the operation is performed 10 times, 5
1 mass%, 5 mass% by repeating 0 times and 100 times
And 10 mass% W plating.

(2) Electroless Ni-P alloy plating A polyethylene heater (capacity: 20 L) was heated by a heating heater.
Using an electroless plating apparatus provided with a stirrer and
First, pretreatment was applied to the plated diamond fine particles, and then electroless plating of a Ni-P alloy was applied. (A) Pretreatment A stannous hydrochloride solution prepared by mixing 10 g of stannous chloride, 40 ml of hydrochloric acid, and 1 L of distilled water in a beaker was added, and 100 g of diamond fine particles were added thereto. The mixture was stirred for 10 minutes and subjected to a sensitivity treatment. Next, the diamond fine particles are filtered and washed, the stannous chloride solution of the beaker is transferred to another container, and the inside of the beaker is washed.
In palladium chloride 1g, hydrochloric acid 10ml, distilled water 1L
, A fine palladium hydrochloride solution was prepared, diamond fine particles were charged therein, and an activation treatment was performed at room temperature for 10 minutes while stirring. After the treatment, the diamond fine particles were filtered and sufficiently washed. For the beaker, the palladium chloride solution was transferred to another container, and the inside was washed.

(B) Ni-P alloy plating Beaker: 60 g of nickel sulfate and 30 g of sodium acetate
1.5 L of the electroless plating solution mixed at a ratio of 0.1%, and 100 g of pretreated diamond fine particles were charged. The mixture was maintained at 90 ° C. while stirring, and the pH was adjusted to 5 to 6 by adding dilute aqueous ammonia. In the adjusted state, 1.5 L of a reducing solution in which 10 g of sodium hypophosphite was dissolved was added little by little over 2 hours. By this operation, a Ni-P alloy having a weight of 20 mass% after plating could be plated. Similarly, the used amount of the electroless plating solution was 0.8 L, 2.3 L, and 3.L.
By changing to 0 L and 3.8 L, Ni-P alloy plating layers of 10 mass%, 30 mass%, 40 mass% and 50 mass% of the weight after plating were formed, respectively.

(3) Preparation of Diamond Wheel Grinding Wheel The Ni-P alloy-plated diamond fine particles and carbonyl nickel powder [INCO Co., Ltd.]
And a particle size of about 20 μm] were mixed so that the concentration of the diamond fine particles became 100, and press-formed into a plane cup type shape (diameter: 125 to 132 mm, thickness: 10 mm). This is 1100 ° C under normal pressure and reducing atmosphere
And sintered for 60 minutes.

(4) Grinding Test of Grinding Stone Grinding of WC-Co alloy with the above grindstone by dry method at a peripheral speed of the grindstone of 1000 m / min, a table speed of 2 m / min and a cutting depth of 3/100 mm. The ratio (the amount of grinding of the material to be ground / the amount of wear of the grindstone) was determined.

Table 1 shows W plating, Ni-P alloy plating,
It shows the graphitization state and grinding ratio of the grinding wheel,
In the case of W plating, the surface of diamond fine particles was covered almost continuously if the amount of adhesion was 1 mass% or more of the weight after plating. When the W plating adhesion amount is 1 mass% or more, Ni-P
Alloy plating weight is 20-50 mass of the weight after plating
%, The graphitization phenomenon was hardly observed at the interface between the diamond fine particles and the W plating layer, and the grinding ratio was large.

[0030]

[Table 1] (Note 1) The adhesion amount of W plating and Ni-P alloy plating is mass% based on the weight after each metal plating. (Note 2) The P content of Ni-P alloy plating is mass%. (Note 3) The state of W plating coating is the result of observing the surface of diamond fine particles at 50,000 times by SEM.

[0031]

As described above, according to the method of the present invention, metal plating can be applied to diamond fine particles having a particle size of 0.1 to 10 μm. Further, in the case of metal plating, if the lower layer is W-plated and the upper layer is Ni-P alloy-plated, even if the diamond tool is subjected to a heat treatment at the time of fabrication, no graphitization or thermal decomposition of the diamond fine particles occurs. For this reason, the durability of the diamond tool can be enhanced by using the metal-plated diamond fine particles produced according to the present invention.

[Brief description of the drawings]

FIG. 1 is a sputtering apparatus used for W plating on diamond fine particles in Examples.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotary drum, 2 ... Roll, 3 ... Motor, 4 ... Sputtering source, 5 ... Diamond fine particles, 6 ... Heating coil, 7 ... Decompression processing chamber, 8 ... Valve, 9 ... Supply pipe, 10 ...
Ar gas introduction pipe, 11 branch pipe, 12 fluid jet mill, 13 circulation pipe, 14 valve, 15 valve, 16
…Vacuum gauge,

────────────────────────────────────────────────── (5) References JP-A-58-120774 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23C 28/02 C23C 14/14 C23C 18 / 50 C23C 28/00

Claims (2)

(57) [Claims] 1. After W-plating of 1 to 10 mass% of the weight of a diamond fine particle having a particle size of 0.1 to 10 μm as a first layer by a sputtering method on a surface thereof,
The second layer has a weight of 20% after plating by electroless plating.
A two-layer metal-plated diamond fine particle obtained by applying a Ni-P alloy plating of -50 mass% on the first layer. 2. A method in which diamond fine particles are accommodated in a sealed rotating drum, W-plating is applied to the diamond fine particles by a sputtering method while flowing the diamond fine particles by rotation of the rotating drum, and then electroless plating is performed in an aqueous solution. A method for producing two-layer metal-plated diamond fine particles, wherein Ni-P alloy plating is performed by the method described above.