JPH0259470A - Production of diamond sintered body - Google Patents

Abstract

PURPOSE:To produce a high hardness diamond sintered body having superior wear resistance and similar in shape to a product by dispersing diamond powder in a liq. monomer and charging the monomer into a mold at the time when resinification is initiated. CONSTITUTION:Diamond powder or powdery starting material contg. 45-95wt.%, preferably 60-85wt.% diamond powder is dispersed in a liq. monomer, e.g., for resol type phenol resin and the dispersed monomer is charged into a mold similar in shape to a product at the time when the viscosity is somewhat in creased by the initiation of resinification. The resulting molded body is heat- treated, released from the mold and carbonized to form an amorphous carbon molded body made from resin contg. diamond particles. This molded body is sintered at >=1,250 deg.C under >=40kb pressure to obtain a diamond sintered body.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a diamond sintered body useful as a wear-resistant part such as the cutting edge of a cutting tool or a dresser die. [Prior Art] Diamond sintered bodies have high hardness and high wear resistance, and have thus far been used as materials for cutting tool edges, wire drawing dies, and the like.

The method for producing such a diamond sintered body is as follows:
Generally, diamond powder is sintered at high temperature and pressure. However, since such conventional technology uses powdered raw materials, gas is easily adsorbed on the surface of the powdered raw materials, which hinders sintering and leaves unsintered parts. Ta. In addition, since the raw material is powder or a powder-derived compact, gas remains between adjacent powders, and this residual gas cannot be completely degassed, so the pressure generation efficiency in a high-pressure container made of pressure medium is There was a problem that a strong diamond sintered body could not be obtained. In particular, when the raw material is a molded body derived from powder, the strength of the molded body is not high, so it is easily damaged when placed in a high-pressure container, and there is a problem that the workability is poor and mass production is not possible.

Therefore, one of the inventors of the present invention has devised a method for solving the above-mentioned problems by dispersing diamond powder in a liquid monomer, and then processing the liquid monomer into resin and carbonization to form a diamond powder. We proposed a method for producing diamond sintered bodies using a dispersed resin, making amorphous carbon from it, and then using a high-temperature, high-pressure method (Japanese Patent Application No. 62-292477).
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[Problems to be Solved by the Invention] However, even with this technology, the following technical problems remain. In other words, in this technology, a flat diamond sintered body is produced and then processed into a predetermined shape (for example, a disc or a cylinder) as a product, similar to the general manufacturing method of amorphous carbon or element. Because of this, there is a problem that not only is there a large amount of wasted parts due to processing, resulting in poor yield, but also that processing requires a great deal of time and effort. In addition, since only relatively simple shapes can be manufactured, if the obtained diamond sintered body is used as a material for a wire drawing die, for example, a die hole is formed by laser machining or electrical discharge machining after the diamond sintered body is manufactured. There is a need.

The present invention was made to solve these technical problems, and its purpose is to manufacture a diamond sintered body with high hardness and excellent wear resistance in a state closer to the product shape. The purpose of this invention is to provide an optimal method for the production of diamond sintered bodies, thereby increasing productivity in the production of diamond sintered bodies.

[Means for Solving the Problems] The manufacturing method of the present invention that achieves the above object is that after dispersing diamond powder or a raw material powder containing diamond powder in a liquid powder, the liquid powder is dispersed in a liquid powder. - A method for manufacturing a diamond sintered body by a high temperature and high pressure method using diamond powder-dispersed resin-derived amorphous carbon obtained by resinizing and carbonizing the diamond powder, in which diamond powder or a raw material powder containing diamond powder is dispersed. The gist of this method is that it includes a step of filling and molding the liquid monomer into a mold having a shape similar to that of a product while the viscosity increases due to the start of resin formation.

[Function] The outline of the technology related to the existing application is as described above, but in short, since the resin-derived amorphous carbon is produced from a liquid monomer as described below, the resin-derived amorphous carbon serves as a matrix. Diamond powder can be dispersed appropriately, and there is no inconvenience such as gas adsorption as described in the prior art.'7
As a result, we were able to create an optimal diamond sintered body.

Based on these prior art techniques, the inventors of the invention conducted intensive research to develop a technique for obtaining a diamond sintered body in a state closer to the product shape. As a result, by including in the series of steps in the above technology a step of filling and molding a liquid monomer with diamond powder dispersed therein into a mold with an approximate shape of the product in a state of increased viscosity due to the start of resinization, the desired result can be achieved. It was discovered that a diamond sintered body could be realized, and the present invention was thus completed. Note that the reason why the shape is approximate to the product is to take into consideration cutting by wire cutting, polishing, lamp finishing, etc. after sintering.

Resin-derived amorphous carbon is also called glassy carbon, and a typical example is phenol resin-derived amorphous carbon, which is obtained by heat-treating and carbonizing a liquid resol type resin. Therefore, in the case of using phenol resin-derived amorphous carbon as the resin-derived amorphous carbon in the present invention, diamond powder is mixed and dispersed in liquid buenol and then heat-treated to obtain an appropriate viscosity by converting the phenol into a resin. After reaching the desired temperature, the product is filled into a mold with a shape similar to the product, followed by heat treatment to harden it, then released from the mold, and further carbonized.
Solid phenolic resin-derived amorphous carbon containing a predetermined diamond powder and having a shape similar to that of the product is obtained. The diamond powder-containing resin-derived amorphous carbon obtained in this way is degassed under high-temperature vacuum, and then brought into contact with a metal catalyst in a stacked or concentric manner, and sintered under high temperature and high pressure. The derived amorphous carbon itself is also converted to diamond, resulting in a highly hard diamond sintered body as a whole.

Note that the approximate product shape here is a disk shape when manufacturing a diamond sintered body for cutting tips, and a columnar shape when manufacturing a diamond sintered body for wire drawing dies, but it is also a more complicated shape. It can be molded into any shape. Furthermore, glass, Teflon, or the like can be used as the material for the mold.

Resin-derived amorphous carbon containing dispersed diamond powder is a dense solid substance, and after being treated with a strange gas, it absorbs less gas components and forms a molded body in which the raw material powder is uniformly coated with carbon. .

The above-mentioned resin-derived amorphous carbon is formed into a single piece by amorphous carbon bonds, and has higher strength than a powder compact, so it can avoid damage when installed in a high-pressure container. , it has good workability and can be mass-produced. In addition, since a diamond sintered body with a shape similar to that of the product can already be obtained at the stage of manufacturing it, the processing steps mentioned in the conventional technology can be omitted, and from this aspect as well, it contributes significantly to productivity improvement. Become.

In the above explanation, phenol resin-derived amorphous carbon obtained by carbonizing phenol resin was shown as a representative example of resin-derived amorphous carbon, but the resin-derived amorphous carbon used in the present invention is derived from phenol resin. , as well as other acetone/furfural copolymer resins, furfuryl alcohol,
Materials derived from thermosetting resins such as phenol copolymer resins, urea resins, melamine resins, xylene resins, and guanamine resins can be similarly treated. Furthermore, these resins are 2 f
ffi or more may be used in combination. Furthermore, when filling a mold with the liquid monomer that forms these resins, it is necessary that the viscosity increases to some extent as the resin formation begins. That is, if a liquid monomer is filled into a mold with a low viscosity, the amount of shrinkage will be large during the period from filling until it is converted into a resin, making it impossible to obtain a resin of a predetermined size and possibly causing cracks.

On the other hand, the sintering temperature for obtaining the desired diamond sintered body is desirably 1250°C or higher, and if it is lower than 1250°C, the sinterability is poor. It goes without saying that the pressure during sintering must be within the thermodynamic diamond stability region, and is preferably about 40 kb or higher. Furthermore, the catalyst used in the sintering process must be an iron group metal such as iron, cobalt, or nickel, and any alloy containing 5% by weight or more of any of the iron group metals will exhibit sufficient catalytic activity. be done. However, if the iron group metal content is less than 5% by weight, the catalytic action will not be exhibited and sinterability will deteriorate.

In addition, in the present invention, the content of diamond powder is 4
It is preferably 0 to 95% by weight. This is because if the content of diamond powder is less than 40% by weight, a large amount of catalyst metal is required to convert amorphous carbon into diamond, so the amount of catalyst metal that remains in the sintered body will inevitably increase. This is because the diamond sintered body becomes inhomogeneous and has a large amount of metal unevenly distributed, making it impossible to obtain a good diamond sintered body. Moreover, if the content exceeds 95% by weight, it becomes difficult to uniformly disperse the diamond powder, and unsintered parts remain in the sintered body. The more preferable content of diamond powder is 60 to 85%.
That's about it.

In the above explanation, only diamond powder is used as the raw material powder for the diamond sintered body.
A similar effect can be expected even if part of the diamond powder is replaced with cubic boron nitride powder, or carbide or nitride powder as the raw material powder.

The present invention will be explained in more detail below with reference to Examples.
The following examples are not intended to limit the present invention, and any design changes in accordance with the spirit of the above and below are included within the technical scope of the present invention.

[Example] Example 1 Liquid resealable phenolic resin 1 synthesized from phenol and formaldehyde using ammonia as a catalyst
20g of diamond powder with a particle size of 2 to 4μm in 0cc
The mixture was dispersed and filled into a mold 3 (see FIG. 1) prepared by bonding a Teflon plate 1 of 31III11 thickness with a plurality of holes 5 (9 in this example) of 10 mm◆ to a glass plate 2 (see FIG. 1). After holding at 60℃ for 2 days and 70t for 3 days,
It was heated to 140 tons to harden it. Mold 3 of the hardened resin
A disk-shaped sample of 10 mm x 5 mm was obtained.

The obtained sample was heated to 900° C. in a nitrogen atmosphere to carbonize it to obtain a disc-shaped dense solid amorphous carbon derived from a phenolic resin in which diamond powder was dispersed.

This was further heated to I
Degassed with.

The diamond powder-dispersed resin-derived amorphous carbon thus obtained was sandwiched between a 0.31-thick 00 disk and a 1.5-mm-thick cemented carbide, and placed in a high-pressure container at 60 kbar and 1
Sintering was performed at 500°C. The hardness of the obtained sintered body is H
v7800 and had a uniform structure.

Comparative Example 1 Only diamond powder with a particle size of 2 to 4 μm was used in a thickness of 0.3 m.
When they were laminated into 00 disks with a thickness of m and filled in a high-pressure container in that state and sintered at 60 kilobar and 1500°C, some unsintered parts remained and hardness could not be measured.

Comparative Example 2 Diamond powder was dispersed in liquid phenol resin at the same mixing ratio as in Example 1, and heated and hardened in a 70×70×3 (cm) container under the same conditions as in Example 1. Next, this plate-shaped sample was carbonized by heating to 900°C in a nitrogen atmosphere, and then a 10 mm diameter disk-shaped sample was punched out using an ultrasonic processing machine, and the recovery rate as a sample was about 40%. This was so low that most of them had to be discarded.

Example 2 A diamond sintered body for a wire drawing die was manufactured in the same manner as in Example 1 except that the mold 3a shown in FIG. 2 was used.

The mold 3a used at this time was one in which three holes 5 of 5 mm diameter were formed in the Teflon plate 1, and a hole 5 was formed in the center of the hole 5.
A core 7 with a diameter of 1 mm is erected, and a hole for a line is formed in the amorphous carbon derived from the diamond powder dispersed resin by this core 7. In addition, when sintering diamond from the amorphous carbon, a boron nitride sintered body of the same shape is inserted into the hole formed in the amorphous carbon by the core 7, and a carbide sintered body with an outer diameter of 10 mm is Sintering was performed using an alloy ring as an outer cylinder.

After sintering, the boron nitride sintered body can be easily removed and is approximately 1 mm thick.
A diamond sintered body for wire drawing dies having a die hole of Through this series of manufacturing steps, the drilling process using laser machining or electric discharge machining, which was previously necessary, could be omitted.

[Effects of the Invention] As described above, according to the present invention, by employing the above-described configuration, a diamond sintered body having high hardness and excellent wear resistance can be manufactured in a state closer to the product shape. As a result, the conventionally required processing steps can be omitted, resulting in improved productivity.

[Brief explanation of the drawing]

FIGS. 1 and 2 are schematic diagrams illustrating molds used in carrying out the present invention. 1...Teflon plate 2...Glass plate 3.3a・
... Mold 5 ... Hole 7 ... Core Fig. 1 Fig. 2/3

Claims (1)

[Claims] Diamond powder or a raw material powder containing diamond powder is dispersed in a liquid monomer, and then the liquid monomer is resinized and carbonized. Diamond powder-dispersed resin-derived amorphous carbon is used as a raw material, and a high-temperature/high-pressure method is used. In the method of manufacturing a diamond sintered body, diamond powder or a liquid monomer in which diamond powder-containing raw material powder is dispersed is filled into a mold with an approximate shape of the product and molded while the viscosity increases due to the start of resinization. A method for producing a diamond sintered body, comprising the steps of: