JP3346609B2 - Fiber reinforced ceramics 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 fiber-reinforced ceramic which contains a super-hard material such as diamond and cubic boron nitride and which contains a fibrous substance such as whisker and which is excellent in high toughness and which is particularly suitable for tools. And its manufacturing method.

[0002]

2. Description of the Related Art Conventionally, sintered bodies made of diamond or cubic boron nitride have a high hardness and are therefore used as various cutting tools. For example, a diamond sintered body is used for cutting an aluminum alloy or FRP, and a cubic boron nitride sintered body is used for cutting steel.

[0003]

Problems to be Solved by the Invention However, diamond and cubic boron nitride (cBN) sintered bodies are excellent in wear resistance, but are inferior in toughness. For example, when used as a cutting tool, the cutting edge is easily chipped. There were drawbacks.

[0004]

[Means for Solving the Problems] The present inventors have repeatedly studied the above problems, and as a result, since titanium charcoal and nitride are originally excellent in nonreactivity with iron, Even if added to diamond or cBN,
It has been found that the wear resistance of BN does not deteriorate, and that the addition of BN as a whisker can provide very excellent toughness. Based on this, the titanium compound whisker is replaced with diamond or cB.
By dispersing N-type ceramics into the N-type ceramics, the above-mentioned drawbacks in terms of toughness were eliminated, and a material having excellent toughness was obtained.

That is, the fiber reinforced ceramics of the present invention comprises:
At least one of diamond and cubic boron nitride and at least one of titanium carbide whiskers, nitride whiskers and carbonitride whiskers;
Volume% and titanium carbide, nitride and carbonitride
At least one kind of particles of 10 to 25% by volume.
It is desirable that whiskers having a diameter of 5 μm or less and an aspect ratio of 3 or more be contained in the whiskers in an amount of 5% or more.

[0006] In the method of manufacturing fiber-reinforced ceramic of the present invention, carbide whiskers titanium, at least one 5 of the nitride whiskers and carbonitride whiskers
95% by volume , at least one of diamond and cubic boron nitride or a raw material to be converted to them during the process, and a small amount of titanium carbide, nitride and carbonitride.
At least one kind of powder of 10 to 25% by volume is mixed, and the mixture is sintered by applying a pressure of 1 GPa or more and a temperature of 1000 ° C. or more.

Hereinafter, the present invention will be described in detail. The diamond powder or cBN powder used in the present invention itself is composed of a single crystal or polycrystal, and has an average diameter of 20 μm or less, preferably 1 to 4 μm. If the average diameter exceeds 20 μm, the bending strength of the sintered body decreases. When the average diameter is 1 μm or less, mixing and the like become difficult and productivity is reduced, but bending strength and the like tend to be improved.
As a method for producing these powders, an ultra-high pressure synthesis method, a gas phase synthesis method, or the like is suitably used. Further, a raw material such as graphite, amorphous carbon, or hBN that is converted into diamond or cBN by firing may be used. In this case, it is effective to use a known catalyst for promoting the conversion.

The fiber reinforced ceramics of the present invention contains diamond or cBN and at least one of titanium carbide whiskers, nitride whiskers, and carbonitride whiskers.
5% by volume. If it is less than 5% by volume, the effect of improving toughness is poor, and the sintered body is likely to be broken.

If it exceeds 95% by volume, abrasion resistance tends to decrease. The desired amount of whisker varies depending on the application, but when used for a cutting tool, 30 to 6 is required for cutting steel.
0% by volume, 15 to 40% by volume for cutting cast iron, 50 to 95% by volume for heavy cutting, and 5 to 40% by volume for light cutting.

It is preferable that the whiskers have a diameter of 5 μm or less and an aspect ratio of 3 or more in the total amount of the whiskers in an amount of 5% or more. Practically 10 whiskers
%, Optimally 25% or more. If the diameter of the whiskers having a diameter of 5 μm or less and the aspect ratio of 3 or more is less than 5%, the effect of improving the toughness is reduced.

Further, the amount of oxygen in the whisker raw material is 3
It is desirable that the content be not more than weight%.

[0012] When the oxygen content in the whisker is more than 3% by weight, the abrasion resistance is liable to decrease when used as a cutting tool. The oxygen content is optimally 1.5% by weight or less.

Further, the fiber reinforced ceramics of the present invention comprises:
A diamond or cBN, a titanium compound whiskers, further are those containing at least one particle of titanium carbide, nitride and carbonitride. The titanium compound particles are dispersed between diamond or cBN or whiskers to strengthen the bond between the diamond and cBN particles and improve toughness, hardness, strength and cutting performance. The particle diameter of the titanium compound particles is desirably smaller than the diameter of the whisker and the diameters of cBN and diamond. This is to fill gaps between diamond and cBN particles and gaps formed between them and whiskers. These titanium compound particles are partially Ti
When C is generated and contacts with cBN, TiB ₂ and TiN are partially generated and strongly bonded to each other. For this reason, the toughness is improved by the whiskers and a strong sintered body can be formed. It is desirable that the titanium compound particles be contained at 2% by volume or more based on the total amount. This is because if it is less than 2% by volume, the effect of improving the strength, hardness, toughness and cutting performance hardly appears. It is particularly desirable that the titanium compound particles be contained in an amount of 10 to 25% by volume based on the total amount.

According to the present invention, at least one of aluminum nitride and titanium boride may be contained in addition to the diamond, cBN, and whiskers. These are effective in strengthening the bond between whiskers or particles of carbide, nitride or carbonitride of titanium and diamond or cBN, and improving the transverse rupture strength.
The content of aluminum nitride and titanium boride is 1 to 30
% By volume, preferably 10 to 20% by volume.

In order to manufacture such a fiber-reinforced ceramic, for example, at least one of whiskers made of titanium carbide, nitride and carbonitride, and at least one of diamond and cubic boron nitride or Raw materials to be converted into them during the process, and, if desired, at least one powder of titanium carbide, nitride and carbonitride, titanium, aluminum, nickel,
Cobalt and at least one powder of these compounds are mixed at a predetermined ratio and fired. When adding titanium, aluminum, nickel and cobalt, the average diameter is 1
It is desirable to add as a metal powder or boride of 0 μm or less.

After the pulverization, it is formed into a predetermined shape. Examples of these forming means include a die press, a cold isostatic press, and extrusion.

It is desirable to select low values of the temperature and pressure during firing so long as diamond and cubic boron nitride are not decomposed and a dense sintered body can be obtained. During the firing step, a step of applying a pressure of 1 GPa or more and a temperature of 1000 ° C. or more to perform sintering is provided. Here, the reason for sintering by applying a pressure of 1 GPa or more and a temperature of 1000 ° C. or more is to obtain a dense sintered body while suppressing the decomposition of diamond and cBN. For the firing, an ultra-high pressure synthesis method is applied. Calcination is optimally performed at a temperature of 1200 to 1850 ° C., and may be performed in a reducing atmosphere in which an inert gas such as Ar or He or carbon exists.

[0018]

According to the fiber reinforced ceramics and the method for producing the same of the present invention, titanium carbide whiskers, nitride whiskers, and titanium whiskers are contained in a component consisting of diamond and cubic boron nitride.
By including at least one of carbonitride whiskers, it becomes possible to improve the toughness in addition to the good wear resistance inherent to diamond and cubic boron nitride. Further, by including at least one kind of particles of titanium carbide, nitride and carbonitride in the fiber reinforced ceramic of the present invention, diamond, cBN,
Fill the whiskers with titanium compound (whisker,
Particles) contact TiC, cB
TiB ₂ and TiN are generated in the portion in contact with N, and they are firmly bonded to each other, so that toughness, hardness, strength, and cutting performance can be improved.

Further, by containing whiskers having a diameter of 5 μm or less and an aspect ratio of 3 or more in the total amount of the whiskers, the generation of voids and defects in the sintered body can be suppressed.

Further, a pressure of 1 GPa or more and 1000 ° C.
By performing sintering by applying the above temperature, a dense sintered body can be obtained without decomposing cBN or diamond.

Hereinafter, the present invention will be described with reference to the following examples.

[0022]

Reference Example Diamond or cBN powder having an average particle diameter of 1 μm or less and a purity of 99.9% or more and, if desired, predetermined raw material powders were weighed in the amounts shown in Table 1, and then mixed and pulverized for 1 hour by a rotary mill. A predetermined amount of titanium carbide, nitride, and carbonitride whiskers (average oxygen content of 1 to 3% by weight) is added to this mixed powder, sealed in a nylon pot together with nylon balls, and mixed for 1 hour by a rotary mill. Was. The slurry after mixing was dried to obtain a raw material for firing. This raw material was filled in a carbon mold and fired at a temperature and a pressure shown in Table 1 for 0.5 hours at an ultra-high pressure.

[0023]

[Table 1]

3 × 3 × 13 m for each sample obtained
The fracture toughness was measured by a dent method using a diamond indenter for micro-Vickers hardness and a Vickers hardness of 1 kg and a load of 20 kg using a diamond indenter for Vickers hardness. In addition, a wear test was performed on each sample containing cBN under the following cutting conditions, and the flank wear after cutting and a chipping test were performed. Here, the case where there was no loss was evaluated as ○.

(Abrasion test) Work material SKD11 Cutting speed 100 mm / min Cutting depth 0.5 mm Feeding 0.1 mm / rev Cutting time 10 min (breakage test) Work material SKD11 (with 4 grooves) Cutting speed 100 mm / min Cutting depth 0 0.5 mm feed 0.1 mm / rev Cutting time 10 min In the case of diamond, a wear test and a chipping test were performed by replacing the work material with an aluminum silicon alloy. Table 2 shows the characteristic evaluation results.

[0026]

[Table 2]

According to Tables 1 and 2, the sample No. 1 to 1
No. 6 has a strength of 58 kg / mm ² or more and a hardness of 27.8 G
It is Pa or more, the toughness is 7.4 or more, and it can be seen that the cutting test also has excellent characteristics. The ratio of whiskers in Table 1 indicates the ratio of whiskers having a diameter of 5 μm or less and an aspect ratio of 3 or more to the total amount of whiskers.

EXAMPLE The present inventors added the titanium carbide, nitride and carbonitride powders as shown in Table 3 with the same diamond, cBN content and firing conditions as in the above reference example . The strength, hardness, toughness, wear amount in a cutting test and fracture resistance were measured in the same manner as in the above reference example . Table 4 shows the results. Table
Sample Nos. 3 and 4 3, 11, and 12 are comparative examples.

[0029]

[Table 3]

[0030]

[Table 4]

According to Tables 3 and 4, the samples within the scope of the present invention have a strength of at least 65 kg / mm ² and a hardness of 30.0 GP.
a), toughness is 8.0 or more, and the cutting test also has excellent properties, and the properties are improved when titanium carbide, nitride, or carbonitride powder is added compared to when not added. I understand.

[0032]

As described above in detail, according to the present invention, at least one of titanium carbide whiskers, nitride whiskers, and carbonitride whiskers is used as a fibrous substance contained in diamond or cubic boron nitride ceramics. As a result, the reactivity with iron oxide is reduced, and excellent wear resistance, toughness and strength are obtained, and the use of fiber reinforced ceramics as a tool material that can be used for any work material or for other mechanical parts Can be expanded.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C22C 29/16 C04B 35/80 G (56) References JP-A-2-267169 (JP, A) JP-A-4-74765 ( JP, A) JP-A-4-144966 (JP, A) JP-A-5-105599 (JP, A) JP-A-4-108664 (JP, A) JP-A-4-108866 (JP, A) JP Hei 2-116673 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 35/52 C04B 35/583 C22C 26/00 C22C 29/16

Claims (3)

(57) [Claims] At least one of diamond and cubic boron nitride, at least one of titanium carbide whiskers, nitride whiskers and carbonitride whiskers in an amount of 5 to 95% by volume, titanium carbide, nitride and titanium
10 to 25% by volume of at least one type of carbonitride particles
And fiber-reinforced ceramics. 2. The fiber-reinforced ceramics according to claim 1 , wherein whiskers having a diameter of 5 μm or less and an aspect ratio of 3 or more are contained in an amount of 5% or more of the total amount of the whiskers. Wherein titanium carbide whiskers, at least one of the nitride whiskers and carbonitride whiskers 5
And 95% by volume , at least one of diamond and cubic boron nitride or a raw material to be converted into them during the process, and a small amount of titanium carbide, nitride and carbonitride.
At least one kind of powder of 10 to 25% by volume is mixed, and the mixture is sintered by applying a pressure of 1 GPa or more and a temperature of 1000 ° C. or more.