KR950008611B1 - Method and apparatus for ceramic materials - Google Patents

Abstract

The ceramic material is produced by (a) mixing some element powders of carbides selected from silicon carbide (beta-SiC), boron carbide (B4C), chromium carbide (Cr3C2), hafnium carbide (HfC), molybdenum carbide (MO2C) or tungsten carbide (WC), and pressing the mixt. to make a molded reactant, (b) filling the reactant in the mixed powder of a titanium (Ti) and a carbon (C), and (c) igniting and burning the mixed powder with a carbon dioxide (CO2) laser beam, and sintering the reactant at 2700-3200 K within one min.

Description

Manufacturing method and apparatus of ceramic material using chemical furnace

1 is a schematic diagram of an SHS reaction vessel according to the present invention.

* Explanation of symbols for the main parts of the drawings

10 Reaction vessel 12 Chemical furnace

14 gas passage 16: water cooling jacket

18, 20: Windows 22: Laser One

24: mixed powder 26: reactant

28: vacuum pump 30: cooling water inlet

32: gas inlet 34: gas outlet

36: cooling water discharge port 38: switchgear

40: ignition pellet

The present invention relates to a method for manufacturing a ceramic material using a chemical furnace and an apparatus used therein. In particular, when producing titanium carbide (TiC) having a high reaction rate, other ceramic powders such as silicon carbide (β-SiC), boron carbide (B ₄ C), chromium carbide (Cr ₃ C ₂ ), hafnium carbide (HfC), Method for producing carbides such as molybdenum carbide (Mo ₂ C) and tungsten carbide (WC) and borides such as molybdenum boride (MoB) and tungsten boride (WB) with excellent mechanical properties and high purity It is about.

Conventionally, since the method of manufacturing a ceramic material of carbide and boride is sintered by heating for a long time in an electric furnace or a kiln, production costs such as fuel costs due to production facilities and heating are considerably high, and due to the generation of oxides, etc. It is difficult to obtain a high-purity product, there was a problem that the industrial usefulness is greatly reduced.

Accordingly, the present inventors have intensively researched to solve such a conventional problem. As a result, the present inventors have found that carbides and borides that are difficult to be manufactured by the conventional sintering method using reaction heat generated when titanium carbide (TiC) is produced through a new chemical furnace. By reacting the reactants, it was found that the ceramic material having excellent mechanical properties can be produced more simply with high purity, thereby completing the present invention.

That is, an object of the present invention is to provide a method for producing a ceramic material with high purity without contamination due to the production of oxides and nitrides on the surface.

Another object of the present invention is to provide a method for producing a ceramic material having excellent mechanical properties in a short time by a simpler process.

Still another object of the present invention is to provide an apparatus for manufacturing a ceramic material, which can reduce equipment and production costs, and can use exothermic reaction heat for direct sintering.

Hereinafter, the present invention will be described in detail.

The present invention is to be produced silicon carbide (β-SiC), boron carbide (B ₄ C), chromium carbide (Cr ₃ C ₂ ), hafnium carbide (HfC), molybdenum carbide (Mo ₂ C), tungsten carbide (WC) Preparing a molded reactant by mixing and applying an element powder of a carbide selected from molybdenum boron (MoB) tungsten boron (WB) or a boride selected from molybdenum boron (MoB) or tungsten boron (WB) And embedding the reactant in a mixed powder of titanium (Ti) and carbon (C), and igniting and burning the mixed powder of titanium (Ti) and carbon (C) with a CO ₂ laser beam. It is a method for producing a ceramic material using a chemical furnace, characterized in that by sintering the reactant at an exothermic temperature of 3200K (2426.84 ℃ to 2926.84 ℃).

In addition, the present invention is provided with a NaCl window through which the laser beam passes on one outer surface, inside the 100-mesh atomic mixture powder of titanium (Ti) and carbon (C) and silicon carbide (β- to be prepared) Carbide or molybdenum boron (MoB) or SiC, boron carbide (B ₄ C), chromium carbide (Cr ₃ C ₂ ), hafnium carbide (HfC), molybdenum carbide (Mo ₂ C) or tungsten carbide (WC) Graphite chemistry is installed in which tungsten boride (WB) element mixed powder reactants of borides are contained together, but the sintered reactants are produced by the heat generated by burning the atomic mixture powder by irradiation with the laser beam. It is characterized in that the manufacturing apparatus of the ceramic material.

When described in detail based on the accompanying drawings of the present invention as follows.

In the present invention, when generating titanium carbide (TiC) and titanium silicide (Ti ₅ Si ₃ ) having a large reaction heat, cubic-type silicon carbide (β-SiC) and boron carbide (B) which are difficult to manufacture by conventional sintering methods ₄ C), chromium carbide (Cr ₃ C ₂ ), hafnium carbide (HfC), molybdenum carbide (Mo ₂ C), carbides of tungsten carbide (WC) or boron of molybdenum boron (MoB), tungsten boride (WB) The present invention relates to a method for producing a ceramic material of a cargo simply or with high purity using the heat of reaction generation and to an apparatus used therein.

In the present invention, the ceramic materials to be produced using the heat of reaction generation of titanium carbide (TiC) and titanium silicide () are carbides and borides, and examples of the carbides include silicon carbide (β-SiC) and boron carbide ( B ₄ C), chromium carbide (Cr ₃ C ₂ ), hafnium carbide (HfC), molybdenum carbide (Mo ₂ C), or tungsten carbide (WC), and as the boride, for example, molybdenum boride (MoB) Or tungsten boron (WB).

And borides are, for example, molybdenum boron (MoB) or tungsten boron (WB).

As the reactants of the ceramic materials to be prepared according to the present invention, the elements of carbide or boride are mixed in a molar ratio purified in a powder state and molded by applying a pressure of about 0.1 ton physically.

For example, when producing silicon carbide (β-SiC), a mixture of a silicon (Si) atom and a carbon (C) atom powder in a molar ratio of 1: 1 is used as a reactant and molded.

In the case of boron carbide (B ₄ C), the mixture / molding of boron (4B) and carbon (C), in the case of chromium carbide (Cr ₃ C ₂ ), the mixture / molding of chromium (3Cr) and carbon (2C), carbonization In the case of hafnium (HfC), the mixture / molding of hafnium (Hf) and carbon (C), in the case of molybdenum carbide (Mo ₂ C), the mixture / molding of molybdenum (2Mo) and carbon (C), tungsten carbide (WC) In the case of tungsten (W) and carbon (C) mixture / molding, in the case of molybdenum boron (MoB), the mixture / molding of molybdenum (Mo) and boron (B) and tungsten in case of tungsten boron (WB) A mixture / molded product of (W) and boron (B) is used as reactant.

In the present invention, the mixture is molded at a pressure of about 0.1 ton in order to facilitate separation of the final product from the titanium (Ti) and carbon (C) powder deposited around the reactants. In particular, when the pressure is less than 0.1 ton, the separation of titanium (Ti) and carbon (C) powder and the final product, which is used as a kind of fuel, and the final product are not only difficult to separate after the reaction, but also contaminants may be contaminated. Will be very high.

On the other hand, Figure 1 is a schematic view showing the configuration of a self propagation high temperature synthesis (SHS) reaction vessel which is a device used to manufacture a ceramic material according to the present invention.

1, the SHS reaction vessel 10, which is a ceramic material manufacturing apparatus according to the present invention, is loaded with a titanium (Ti) powder, a carbon (C) powder, and a graphite chemical furnace 12 filled with the reactants. . Between the inner and outer walls of the reaction vessel 10, a gas passage 14 through which N ₂ gas passes, and a water cooling jacket 16 through which cooling water passes, and a NaCl window 18 on the outer surface of the reaction vessel 12. ) And a quartz window 20 are provided.

Reference numeral 22 is a laser source, and an arrow (→) indicated by a dotted line is a laser beam.

The inner and outer walls of the SHS reaction vessel 10 according to the present invention are made of stainless steel to control the atmosphere, and the inner and outer walls cool the heat generated during the reaction with the gas passage and the gas passage 14 for vacuum. The water cooling jacket 16 is provided.

The graphite chemical furnace 12 installed inside the reaction vessel 10 is capable of withstanding the heat generated by the SHS reaction, and blocks the heat generated first.

At least one or more of the mixed powder 24 of the titanium (Ti) and carbon (C) and the reactant 26 are filled in the graphite chemical furnace 12.

One side of the reaction vessel 10 according to the present invention is provided with a NaCl window 18, the other side is provided with at least one quartz window 20. This quartz window 20 can be installed as needed.

The NaCl window 18 serves to pass the laser beam radiated in the direction of arrow (→) from the CO ₂ laser source 22 and to send it into the graphite furnace 12 of the reaction vessel 10.

In addition, the quartz window 20 is installed to see a phenomenon in which the reactants are reacted from the outside.

Meanwhile, reference numeral 28 is a vacuum pump, 30 is a cooling water inlet, 32 is an N ₂ gas inlet, 34 is an N ₂ gas outlet, 36 is a cooling water outlet, 38 is a switch, and 40 is an ignition pellet.

The process of manufacturing the ceramic material using the apparatus according to the present invention is as follows. First, the reactant 24 is embedded in the graphite chemical furnace 12, but a mixed powder of titanium (Ti) and carbon (C) having a size of 100 mesh used as a fuel in the inner bottom part of the graphite chemical furnace 12 ( 24) is about 20 mm thick, and at least one highly compact compacted material (26: green compact) is placed thereon, and then the fuel powder is filled around the reactant (26) to the mixed powder (24). Allow it to be completely reclaimed.

At this time, the ratio (mass ratio) of the mixed powder 24 and the reactant 26 is preferably as shown in Table 1 below.

Table 1

If the fuel and the reactant are filled at or above the ratio as shown in Table 1, the reactant will not react, especially in the case of silicon carbide (SiC), the α- and β-forms in the final product. This coexists, and the desired product cannot be obtained in the present invention.

After embedding the reactant 26 as described above in the fuel of the mixed powder 12, the CO ₂ laser beam from the laser source 22 is passed through a NaCl window 18 to a 325 mesh-sized titanium (Ti) powder and carbon ( C) The ignition pellet 40 made of powder is irradiated and ignited.

After the ignition pellet 40 is ignited, combustion of the mixed powder 24 of titanium (Ti) and carbon (C) serving as a fuel in the graphite chemical furnace 12 is caused by propagation of combustion waves.

The output of the CO ₂ laser light used in the present invention is about 10W, the irradiation time can be ignited by a few seconds of instantaneous irradiation until the reaction starts, and if the irradiation of the laser light is stopped after ignition, the reaction proceeds It is spontaneously progressed by its own combustion wave.

As described above, when the mixed powder 24 is burned, the reactant 26 is reacted by the heat of combustion and the silicon carbide (β-SiC), boron carbide (B ₄ C), and chromium carbide (Cr) desired in the present invention. ₃ C ₂ ), hafnium carbide (HfC), molybdenum carbide (Mo2C), tungsten carbide (WC) carbides or molybdenum boron (MoB), tungsten boride (WB) of the ceramic material can be obtained.

At this time, the reaction of the reactant 26 is made within about 1 minute, and the exothermic temperature of about 2700K to 3200K (2426.84 ℃ to 2926.84 ℃) is released by the combustion of titanium (Ti) and carbon (C) instantaneously The reaction is complete.

The ceramic material of carbide or boride prepared according to the method and apparatus according to the present invention exhibits high purity without contamination and incomplete reaction from titanium and carbon mixed powder as a single structure.

Advantages of the present invention are as follows.

First, investment in production equipment and production costs can be reduced by simplifying the process.

Second, since the exothermic heat generated during the reaction is used for direct sintering, energy can be saved.

Third, unlike the conventional method, the reactivity is weak, and thus, it is easy to manufacture a ceramic material, which is difficult to manufacture.

Fourth, since reaction generation occurs at a very high temperature in a short time, there is no inconvenience of long-term sintering at a high temperature for several or several days.

Fifth, unlike the conventional method, since there is no contact with the atmosphere, it is possible to manufacture a high-purity ceramic material without contamination such as oxide and nitride formation.

Claims (8)

Carbide selected from silicon carbide (β-SiC), boron carbide (B ₄ C), chromium carbide (Cr ₃ C ₂ ), hafnium carbide (HfC), molybdenum carbide (Mo ₂ C), or tungsten carbide (WC) Preparing a shaped reactant by mixing and powdering elemental powders; embedding at least one of the reactants in a mixed powder of titanium (Ti) and carbon (C); and Ceramic powder using a chemical furnace characterized in that the mixed powder of (C) is ignited and burned with a CO ₂ laser beam to sinter the reactant within 1 minute at an exothermic temperature of about 2700 to 3200K (2426.84 to 2926.84 ℃). Manufacturing method. The method of claim 1, wherein the reactant is mixed according to the molecular molar ratio of each carbide to be prepared. The method of claim 1, wherein the mixed powder and the reactant of titanium and carbon are 2: 1 for β-SiC, 1: 1 for B ₄ C, 1: 1 for Cr ₃ C ₂ , and 1 for HfC. : 1, 6: 1 for MoC2 1, ₁ : 1 for WC. A stainless steel SHS reaction vessel 10 having a NaCl window 18 through which a laser beam passes on one outer side thereof, and an atomic mixture powder of titanium (Ti) and carbon (C) having a size of 100 mesh inside thereof (24). ) And silicon carbide (β-SiC), boron carbide (B ₄ C), chromium carbide (Cr ₃ C ₂ ), hafnium carbide (HfC), molybdenum carbide (Mo ₂ C), and tungsten carbide (WC) A graphite chemical furnace 12 is provided in which a reactant 26 of an element mixed powder of boride selected from selected carbides or molybdenum boron (MoB) or tungsten boride (WB) is housed together. Apparatus for producing a ceramic material to sinter the molded body (26) with the generated heat generated by burning the reactant (24). 5. The apparatus according to claim 4, wherein a water cooling jacket (16) through which cooling water passes, and a gas passage (14) for vacuum and a vacuum are installed between the inner and outer walls of the reaction vessel (10). Mixing an element powder of a boride selected from molybdenum boron (MoB) or tungsten boron (WB) to be prepared and applying a pressure to prepare a molded reactant, and at least one of the reactants is made of titanium (Ti) and carbon (C) filling the mixed powder of (C) and igniting and burning the mixed powder of titanium (Ti) and carbon (C) with a CO ₂ laser beam to an exothermic temperature of about 2700 to 3200K (2426.84 to 2926.84 ° C). Method for producing a ceramic material using a chemical furnace characterized in that the reaction is prepared by sintering within 1 minute. 7. The method of claim 6, wherein the reactants are mixed according to the molecular molar ratio of each boride to be prepared. The method of claim 6, wherein the mixed powder and reactant of titanium and carbon are 1: 1 for MoB and 1: 1 for WB.