JPS5848621B2 - Silicon carbide technology - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an ultra-hard composite material reinforced with silicon carbide fibers.

Conventionally, cemented carbide has the fatal flaw that it cannot withstand high-speed cutting or heavy cutting that generates intense heat because WC, which is one of the main components, is easily oxidized and decomposed at relatively low temperatures. Because it has the property of easily causing welding with steel at low temperatures, it produces a so-called "structured cutting edge" even in low-speed cutting ranges, which significantly impairs the precision of the cutting surface.
Often reduces tool life.

Furthermore, in recent years, TiC-based cermets have been developed and put into practical use, but they have problems with transverse rupture strength and toughness.
Its scope of use remains extremely limited.

The purpose of the present invention is to produce an ultra-hard composite material that eliminates the defects of ultra-hard carbide as described above, and to manufacture the same.
No., JP-A-51-130324, JP-A-51-130
No. 325, JP 51149925, JP 51-1
No. 49926, JP-A-51-147623, JP-A-5
As shown in the specifications of JP-A-1-147624, JP-A-52-1136, JP-A-52-5321, and JP-A-52-31126, organosilicon polymer compounds are synthesized from organosilicon compounds, and A silicon carbide fiber obtained by spinning an organosilicon polymer compound, heating the spun fiber at a low temperature, and then firing it in a temperature range of 700 to 2000°C is arranged in an aggregate of a mixture of ultrahard carbide and a binding metal. , mold while applying pressure as necessary, and mold under pressure as necessary.
An ultra-hard composite material reinforced with silicon carbide fibers that are sintered at a temperature of 00° C. or higher, allowing the free carbon in the silicon carbide fibers to react with the bonding metal, and improving the bonding properties between the fibers and the bonding metal. This objective can be achieved by providing a method for manufacturing thorns.

Next, the present invention will be explained in detail.

The silicon carbide fiber obtained by heating the spun yarn made of the organosilicon polymer compound used in the present invention at a low temperature and then firing it at a temperature in the range of 700 to 2000 DEG C. is produced by the following method.

In the present invention, the organosilicon compounds that can be used as the base material of the organosilicon polymer compound are the following (1) to (
IO).

(1) Compounds containing only Si-C bonds.

(2) Compounds containing Si-H bonds in addition to SI10 bonds.

(3) Compound having Si-Hal bond.

(4) Compounds having Si-N bonds.

(5) A compound having a Si-OR (R-alkyl, aryl) bond.

(6) A compound having an Si-OH bond.

(7) Compounds containing Si-Si bonds.

(8) A compound containing a Si-0-Si bond.

(9) Organosilicon compound esters.

(10) Organosilicon compound peroxide.

From at least one organosilicon compound belonging to the types (1) to α0), a polycondensation reaction using at least one of irradiation, heating, and addition of a polycondensation catalyst,
Organosilicon polymer compounds whose main skeleton components are silicon and carbon, such as compounds having the following molecular structure, are produced.

(d) A substance containing the skeleton components described in (i) to (/→ as at least one partial structure of a chain or three-dimensional structure, or a mixture of (i), (i), and (/→).

Examples of compounds having the above molecular structure include the following.

(d) Those containing the skeleton components described in (a) to (c) above as at least one partial structure among chain, cyclic, and three-dimensional structures, or a mixture of (i), (i), and (/i).

After spinning the organosilicon polymer compound and heating it at a low temperature in an oxidizing atmosphere in a temperature range of 50 to 400'C, the organosilicon polymer compound is spun and then heated in a vacuum or one or more selected from inert gas, CO gas, and hydrogen gas. 700-200 in an atmosphere of
It is fired at a temperature range of 0°C to obtain silicon carbide fibers.

The reason why the temperature range for the silicon carbide fibers is 700 to 2000°C is that at temperatures below 700°C, the organosilicon polymer compound decomposes and no SiC production or reaction occurs, and when burned at temperatures above 2000°C, Since silicon carbide fibers are violently decomposed, the firing temperature is preferably in the range of 700 to 2000°C.

In the organosilicon polymer compound, as shown in the structural formulas (a) to (d) above, at least 2 mol of carbon exists per 1 mol of silicon, and most of the carbon in the side chain Although it evaporates as a gas, some of the side chain carbon and most of the carbon in the skeleton remain even after firing, so silicon carbide fibers contain more than 1 mol of carbon per 1 mol of silicon. The silicon carbide fiber can be made to contain 0.01% or more of free carbon.

Furthermore, if necessary, the free carbon can be removed by firing in an acidic or arsenic atmosphere to obtain a silicon carbide fiber consisting only of SIC.

The SiO crystals in the silicon carbide fibers develop significantly when the firing temperature is 1000° C. or higher, and the strength and hardness of the silicon carbide fibers increase, and the heat resistance also improves.

As an example, silicon carbide fibers fired at a temperature of 1300'C in vacuum have extremely high bow tensile strength and elastic modulus, are heat resistant, and have oxidation resistance, as shown in Table 1.
It also has excellent corrosion resistance and wear resistance.

In the method of the present invention, HfC, TaC, NbC
, Ta20, TiC, ZrC, VC,
WC, W20, MoC! , Mo2C, Cr3
Co, Ni, Mo, Cu, Fe tA and the silicon carbide fiber are combined with one or more powders selected from ultra-hard carbides such as C2 and SIC.
An ultra-hard composite material which is made by adding one or more selected from A and other metal elements, pressurized and sintered at a temperature of 1000°C or higher to use the silicon carbide fiber as a reinforcing material. can be manufactured.

The silicon carbide fibers are formed from β-SiC crystals.

Comparing the hardness of this β-SiC and ultra-hard carbide, as shown in Table 2, β-SiC is the hardest, and the ultra-hard composite material made of ultra-hard carbide and bonding metal is reinforced with silicon carbide fibers. As a result, a composite material with high strength and hardness can be obtained.

Furthermore, in the composite material, free carbon o. When silicon carbide fibers containing oi% or more are used, the free carbon reacts with the bonding metal to improve the bonding properties between the silicon carbide fibers and the bonding metal.

That is, when silicon carbide fibers containing 0.01% or more of free carbon are used, the free carbon may be Co, Ni, M, etc., as shown in the phase diagrams of FIGS. 1 to 4, for example.
o, Or Dissolves in metal.

A part of the carbon dissolved in the metal at high temperature is precipitated as metal carbide at the interface between the ultra-hard carbide and silicon carbide continuous fibers while being cooled.

The metal carbide strongly binds and bonds the ultra-hard carbide and silicon carbide fibers with the binding metal, so the strength of the ultra-hard material containing the silicon carbide fibers is increased.Furthermore, the carbon dissolved in the binder metal strengthens the binder metal. becomes harder, and its strength and hardness increase.

Among the silicon carbide fibers used in the present invention, the preheated fibers obtained by firing at 700 to 1000°C contain easily volatile low molecular weight hydrocarbons, as shown in FIG.
Contains a small amount of low molecular weight organosilicon compounds.

Therefore, the ultra-hard carbide and preheated fibers are made of Co, Ni.
, Mo, Or, Fe, Kl, and other bonding metal alloys, the easily volatile components generated from the preheated fibers are separated and the carbon element is generated.
Preheated fibers may be more effective as reinforcing bars in composite materials than silicon carbide fibers fired at temperatures above 1000'C because they act similarly to the free carbon.

Moreover, the silicon carbide fiber of the present invention is 12000C
When fired at a temperature above, SiC crystals develop.

Therefore, silicon carbide fibers obtained by firing at temperatures below 1200°C are amorphous.

When amorphous silicon carbide fiber is used as a reinforcing material for an ultra-hard composite material and sintered at a temperature of 1200°C or higher to form crystalline silicon carbide fiber, the silicon carbide in the composite material and the bonding metal The bonding properties are better than when using crystalline silicon carbide, which increases the strength of the ultra-hard composite material.

The method for manufacturing ultra-hard composite material barbs of the present invention has the advantage that conventional methods for manufacturing ultra-hard alloys or cermets can be directly applied. By arranging them three-dimensionally in one direction or along the warp and warp, it is possible to impart directionality to the strength of the ultra-hard composite material, or to eliminate directionality.

As an example of the method for manufacturing the composite material, FIG. 6 shows a process for manufacturing an ultra-hard composite material from titanium carbide.

Titanium carbide powder of 5μ or less and Co, Ni, Or, MO,
One or more metal powders selected from Fe, At, and other binding metals are mixed with a solvent such as methanol, benzene, carbon tetrachloride, or the like.

Silicon carbide fibers are arranged in layers, the gaps between the fibers are filled with the mixture, and the mixture is dried under reduced pressure while being press-molded to form a molded body.

The molded body is first fired in a vacuum or hydrogen gas atmosphere for about 1 hour at a temperature range of 800 to 1100°C, then molded, and the rounded body is fired for a second time in a vacuum at a temperature of 1200 to 1500°C. Sintering is performed for 1 to 3 hours, and the secondary sintered body is mechanically finished with diamond or the like and inspected to produce a product.

Alternatively, after impregnating the secondary sintered body with an organosilicon polymer compound,
The tertiary sintered body is fired in an atmosphere of one or more selected CO gases, and then the tertiary sintered body is mechanically finished with diamond or the like and inspected to produce a product.

The transverse rupture strength and hardness of the ultra-hard composite material of the present invention vary depending on the amount of silicon carbide fiber added.

As an example, when the amount of silicon carbide fibers containing 5% free carbon to be composited with the cemented carbide KIO is changed, the rupture strength and hardness of the cemented carbide KIO change as shown in Figure 7. .

In the figure, the transverse rupture strength and Vickers hardness increase as the amount of silicon carbide fiber increases.

However, the hardness is 14 due to the amount of silicon carbide fibers.
% or more, the hardness decreases, and if it is 20% or more, it becomes smaller than the hardness of cemented carbide KIO, which is not reinforced with fibers.
The amount of silicon carbide fibers is preferably 20% or less, and since the reinforcing effect of the fibers is extremely small if it is less than 1%, the amount of silicon carbide fibers is preferably within the range of 1 to 20%.

In the production of the ultra-hard composite material of the present invention, after secondary sintering, it is impregnated with an organosilicon polymer compound whose main skeleton components are silicon and carbon, which is the original material for spinning, and then in a non-oxidizing atmosphere. By firing at a temperature of 800℃ or higher,
Openings created by secondary sintering can be filled with silicon carbide.

In order to impregnate the secondary sintered body with the organosilicon polymer compound, the organosilicon polymer compound may be impregnated with, for example, benzene, toluene, xylene, hexane, ether, tetrahydrofuran, dioxane, chloroform, methylene chloride, or other organic A carbon product can be impregnated with a solution obtained by dissolving a silicon polymer compound in a solvent, or a solution obtained by heating and melting the silicon polymer compound, for example, by the method described below.

(1) Place the secondary sintered body in a sealable container, degas it by evacuating it at room temperature or high temperature, and then inject the melt of the organosilicon polymer compound or a solution dissolved in a solvent into the container. Then, the secondary sintered body is sufficiently immersed in the organosilicon polymer compound to impregnate it.

Note that pressure can be applied after impregnation if necessary.

(2) Apply an organosilicon polymer compound solution to the surface of the secondary sintered body at room temperature or high temperature by spraying, brushing, or the like.

(3) The carbon product is immersed in the organosilicon polymer compound liquid in an open container.

When the impregnated body obtained by the above methods is calcined at a temperature of 800° C. or higher, the organosilicon polymer compound can be decomposed and SiC can be produced.

An oxidizing atmosphere is not suitable for the calcination because an oxidizing reaction occurs and silicon becomes 8102 and no SiO is produced, and a non-oxidizing atmosphere is required.

That is, the atmosphere includes vacuum, inert gas, CO gas,
It is preferable to incinerate in an atmosphere of one or more hydrogen gases selected from hydrogen gas.

By repeating this impregnation and burning process several times, the ultra-hard composite barb has high specific gravity, strength and hardness, and has excellent heat resistance, corrosion resistance, abrasion resistance, and crater resistance. can do.

As an example, a cemented carbide composite material (TIC55, silicon carbide fiber 5, Ni 3
As shown in Figure 8, the relationship between the number of impregnations of 2, Cr8, specific gravity 5.90) with an organosilicon polymer compound, specific gravity, and transverse rupture strength is as shown in Figure 8. It can be seen that the transverse rupture strength increases rapidly as the number of times increases, indicating that the effect of impregnation is significant.

Next, the present invention will be explained with reference to examples.

Example 1 A cemented carbide material consisting of 94% W0, 5% Ta(Nb)CI, and 5% Oo by weight and corresponding to KIO (JIS) was placed in a bowl, mixed by a wet method for about 100 hours, and then It was dried, pressurized, or shaped into a pre-shaped body according to the manufacturing method of cemented carbide.

In addition, preheated silicon carbide fibers were layered and arranged in soo'c, and WC90, 5%, Ta 0.8%,
5% Co was mixed together with benzene, and the mixture was dried under reduced pressure while being press-molded to obtain a shaped body.

The two precipitated bodies were first fired at 900°C for 1 hour in a hydrogen atmosphere under pressure, and then fired at 1400°C in vacuum.
After secondary sintering for 1.5 hours, a cemented carbide KIO and a cemented carbide KIO reinforced with silicon carbide fibers were obtained.

The transverse rupture strength and Vickers hardness of each are shown in Table 3.

According to the same table, when silicon carbide fibers were added, the transverse rupture strength increased by 40%, and the hardness also increased by approximately 1.4 times.

In addition, when we conducted a cutting test on cast iron Fe20 using this cemented carbide KIO made of silicon carbide continuous fibers, we found that it was approximately 1.
The lifespan was 8 times longer, demonstrating the effect of combining silicon carbide continuous fibers.

Example 2 W0912%, Ta01.9%, TiC0.4 in weight%
%, Co6. 5% cemented carbide and WC 8 8.
0%, TaC1.5%, TiC0.7%, Oo6.8
% and silicon carbide fibers (3.0%) preheated at 750°C were produced in the same manner as in Example 1.

A cutting tool for an automatic lathe was manufactured using these two types of cemented carbide, and a 1.30%φ 13Or martensitic free-cutting stainless steel was cut at a cutting speed of V -20 m/min 1 depth of cut t = 0.02. ~0.03 tomo/piece of meat, feed S=0-
When cutting work was carried out using an automatic lathe with cutting oil circulating under cutting conditions of 0 0 3 mm/rev, the average life of additive-free cemented carbide was 28 hours, but the average life of cemented carbide reinforced with silicon carbide continuous fibers was 28 hours. The average lifespan of cemented carbide has increased by almost three times to 81 hours.

Example 3 Ti06 0%, Ni 24%, Co 8%,
Cermet WZ12b consisting of Or 8% Ti0 5
A cermet consisting of 5% Ni, 24% Ni, 8% Co, 8% Cr, and 5% silicon carbide fibers preheated at 800°C was produced in the same manner as in Example 1 to obtain a cermet having the properties shown in Table 4. .

Cutting speed of 180r stainless steel using 20 tools made from these two types of cermets - 30m/min
% cut depth 0.1mm/one piece, feed S-0. 0 2mn
As a result of cutting work performed under the cutting conditions of / rev, there were several breakage accidents with the conventional product, but none with the cermet made of silicon carbide continuous fibers, and the average life of this cermet is the same as the average life of the conventional product. It was about three times as much.

Furthermore, thermal shock tests were conducted on these two types of cermets.
When tested at a temperature of 1320°C and the number of cycles required to break, the cermet made of continuous silicon carbide fibers showed a 2.
It got 1x better.

Example 4 W082%, TiC5%, ゜Co 9%, 1 in weight%
Composite barbs were manufactured using 4% 300'C treated silicon carbide fibers.

That is, a 120 x 12 x 10 mytt mold was held vertically, and several silicon carbide fibers were placed in the mold through a 325 mesh mesh so that the silicon carbide fibers were uniformly dispersed.

WC, TiC, and Co powders were wetted with n-hexane and placed in a mold provided with silicon carbide, and then the core mold was molded by applying pressure from the side, and was left to dry for several days.

The dried body was incinerated to 900°C in a hydrogen atmosphere for 12
After shaping into 0x10x10 size, 3
Polysilane (average molecular weight approx. 2) melted at 50°C
After impregnating with 000), 130
It was incinerated to 0℃.

After repeating the impregnation and baking (1300° C.) twice, the surface was finished with emery paper to obtain a composite material.

At the same time, a conventional cemented carbide made of 86% W0, 5% Ti, and 9% C3o was manufactured and compared with the composite material. The results are shown in Table 5.

The transverse rupture strength of the composite material is more than 1.3 times that of conventional products.

When the product of the present invention was used to cut cast iron, damage was extremely reduced and wear was reduced by 50% compared to conventional products.

The ultra-hard composite material reinforced with silicon carbide fibers manufactured by the manufacturing method of the present invention has high strength and
It has low hardness and excellent heat resistance, abrasion resistance, acid resistance, corrosion resistance, thermal shock resistance, crater resistance, and welding resistance, making it suitable for cutting tools, press tools, cotton drawing dies, textile thread guides, jet nozzles, Rocket nozzles, aircraft jet and rocket engines, turbine blades, materials for high temperature gas reactors,
Nuclear reactor materials, thermal power generation materials, heat-resistant materials, wear-resistant parts, and all other fields where cemented carbide and cermet are already used today, as well as all other fields that require heat resistance, oxidation resistance, and corrosion resistance. It can be expected to have sufficient effects in the field as well.

[Brief explanation of the drawing]

Figure 1 shows the relationship between the residual weight of the fiber and the heating temperature when spun yarn made of an organosilicon polymer compound is heated at a low temperature and then heated in vacuum from room temperature to 1200°C. Figure 2 shows the relationship between the residual weight of the fiber and the heating temperature. The phase diagram of C, Figure 3 is the phase diagram of Ni-C, Figure 4.
Figure 5 is a phase diagram of Mo-C, Figure 5 is a phase diagram of Cr-C, Figure 6 is a process diagram for producing an ultra-hard composite material from titanium carbide, and Figure 7 is a super-hard composite material reinforced with silicon carbide fibers. Figure 8 shows the relationship between the amount of silicon carbide preheated fiber added and the transverse rupture strength and Bitkers hardness of the cemented carbide KIO in the alloy KIO. It is a figure showing the relationship between the number of times, specific gravity, and transverse rupture strength.

Claims (1)

[Claims] 1. In the aggregate of the mixture of ultra-hard carbide and binding metal,
700 to 200 spinning made of organosilicon polymer compound
A superstructure reinforced with silicon carbide fibers, characterized in that silicon carbide fibers obtained by firing within a temperature range of 0°C are arranged, and then the aggregate is sintered to form a sintered body. Method for manufacturing rigid composite barbs. 2 In the aggregate of the mixture of ultra-hard carbide and bonding metal,
700 to 200 spinning made of organosilicon polymer compound
After disposing silicon carbide fibers obtained by firing within a temperature range of 0°C, this aggregate is sintered to form a sintered body, and the sintered body is impregnated with the organosilicon polymer compound. 1. A method for producing an ultra-hard composite material reinforced with silicon carbide fibers, the method comprising performing an impregnation/firing step at least once, followed by re-baking.