JPH0357044B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing titanium group element nitrides in the form of ingots, and particularly to castings of titanium nitride, zirconium nitride, and hafnium nitride useful for producing grinding abrasive grains, for example. The present invention relates to a manufacturing method for obtaining lumps.

[Prior art] For example, methods for producing titanium nitride include a unique single gas phase reaction method in which powdered metallic titanium is reacted in a nitrogen or ammonia stream, and a method in which titanium hydride is thermally decomposed and then reacted in a nitrogen or ammonium stream. A method based on a solid-gas phase reaction and a method based on a gas-phase reaction in which titanium tetrachloride is reacted with a mixed gas of hydrogen and nitrogen or ammonia gas in a high-temperature gas phase state have been developed. In addition, a laboratory-scale method for producing zirconium oxide using a nitrogen plasma jet was introduced in the ``electrochemistry'' category.
Reported in Volume 36, No. 12 (1968) and "Metal" Vol. 38, No. 15 (1968).

However, the method yields powder or fibrous material, and the method yields titanium nitride mainly for surface coating. All of them are in the form of powder on the order of 1μ. In addition, the method (2) was carried out on a laboratory scale as an attempt to manufacture nitrides by utilizing the high temperature obtained by a nitrogen plasma jet and using nitrogen atoms, nitrogen ions, etc. in the plasma jet as reactive species. Although it is said that a solid product was obtained in this experiment, the size of the product obtained was at most the same as that of the prepared reaction sample. That is, first, after mixing graphite powder of ziconium oxide powder, about 1 g is taken out, pressure molded using propylene glycol as a binder, and sintered at 1100°C for about 4 hours to form a product with a diameter of 15 mm and a thickness. This is simply a matter of obtaining a pellet-like sample of approximately 3 mm in size, bombarding it with a nitrogen plasma jet using a graphite crucible as an anode, and obtaining nitride on the crucible to the same extent as the pellet-like sample.

Therefore, in the past, there was no manufacturing method for directly obtaining titanium nitride as an ingot in the titanium nitride production reaction.

[Problems to be Solved by the Invention] However, when using titanium nitride as, for example, abrasive grains for grinding, it is not preferable to use it as a powder or fibrous material due to its nature, and abrasive grains on the order of 0.3μ may be obtained. Conventionally, powdered titanium nitride obtained by the known method described above is further sintered,
After that, a separate process of pulverizing to a predetermined particle size was required. In other words, in order to obtain titanium nitride that can be used industrially, it is impossible to directly obtain an ingot by known methods due to the production reaction of titanium nitride, so in order to obtain an ingot, it is necessary to Further sintering the powdered or fibrous titanium nitride,
It was made into an ingot and then crushed to produce abrasive grains for grinding. Moreover, since titanium nitride has a high melting point of over 2950°C, it has severe conditions in terms of productivity and processability, and has been an economic problem.

The purpose of this invention is to produce titanium group element nitrides, such as titanium nitride, which are of almost the same quality as conventional powder products, in a production reaction from powder raw materials at the minimum necessary heating temperature without the need for solidification in advance. The object of the present invention is to provide a method for producing titanium group element nitrides, which can be obtained directly in large quantities in the form of ingots and has extremely high industrial productivity.

[Means for solving the problem] As a result of intensive studies to explain the above problem, we added a reducing agent such as coke to the powder of oxides of titanium group elements, and in an electric arc furnace, N ₂ ,
By adopting a production method in which the titanium group element is heated and melted in an atmosphere of NH ₃ or a mixed gas of these gases at least at a temperature higher than the melting point of the nitride, nitrided, and the obtained nitrided melt is solidified. They discovered that nitrides of titanium group elements in the form of ingots can be obtained directly.

In addition, a carbide powder of a titanium group element is used as a raw material, and it is heated and oxidized in a solid state in an atmosphere of a mixed gas of N ₂ and CO ₂ in an electric arc furnace to produce a titanium group element. The oxide of
Similar to the above production method, in an atmosphere of N ₂ , NH ₃ , or a mixed gas thereof, the nitride is heated and melted under heating conditions at least higher than the melting point of the nitride of a titanium group element, and the resulting nitrided melt is nitrided. It has been found that a method of solidification can also be adopted.

Note that oxides of titanium group elements () are not limited to titanium oxide, but also zirconium oxide and hafnium oxide, and in the case of carbides of titanium group elements, titanium carbide, zirconium carbide, and hafnium carbide can be used as raw materials. I don't mind if you do that.

[Function] This invention uses oxides or carbides of titanium group elements as raw materials, and the nitriding reaction, which is the final product reaction, is carried out under heating conditions that are at least higher than the melting point of nitrides of titanium group elements. The process is carried out under active melting conditions, from solids to nitrides, and is finally produced as molten nitrides. Therefore, by solidifying this, the nitriding reaction and the ingot formation are simultaneously caused, so that the titanium group element nitride can be directly obtained as an ingot in the production reaction.

What's more, it can be completely processed in an electric arc furnace, and the maximum heating temperature of an electric arc furnace is approximately
Since it stays at 5000℃, the minimum heating temperature required is
Since it can be produced continuously and all at once, it is also possible to produce large quantities of ingots, and has extremely high industrial productivity.

Further, when a carbide of a titanium group element is used as a starting material, there is an advantage that the production rate is faster than when an oxide is used as a starting material. Furthermore, since this is a manufacturing method in which the carbide is not directly nitrided, but the carbide is first converted to an oxide and then a nitride is obtained, the reaction progresses more easily compared to a method in which the carbide is directly nitrided. That is, if the temperature during the nitriding reaction is set at 2,000 to 5,000°C because of the need to directly form an ingot, the reaction proceeds more easily than in the method of directly nitriding carbides due to the difference in free energy change.
Therefore, when a titanium group element nitride in the form of an ingot is directly produced using a titanium group element carbide as a starting material, it is preferable to use a production method in which the carbide is first converted into an oxide and then a nitride.

[Example] Example 1 10 kg of rutile sand and 3.3 kg of coke are thoroughly mixed. A direct arc type furnace consisting of a furnace body 1, an electrode 2, an AC power source 3, and a nitrogen-containing gas supply path 4 as shown in the drawing is put into an electric furnace and heated to around 3000℃, which exceeds the melting point of titanium nitride. Set the heating conditions,
An AC voltage of 120 V was applied to blow an arc to generate a titanium oxide melt 5 (melting point: 1855° C.).
Next, this melt 5 was heated with N ₂ gas (flow rate 5.0/
Nitriding was performed under the same heating temperature conditions under the min) atmosphere. At this time, the temperature of the melt gradually rises as molten nitrides are generated, and molten nitrides are mixed with molten oxides, and finally 3000
A molten nitride of titanium was obtained which was in a molten state at a temperature around 0.degree. When this was solidified, 6.3 kg (81% of the theoretical yield) of titanium nitride ingots were obtained.
When this ingot-like titanium nitride was identified by powder X-ray diffraction, it was found to be only TiN. In addition, chemical analysis showed that N = 21.6%, and powdered commercial product (N = 22.4
%) was obtained.
In addition, as intermediate products during the reaction, TiO, TiC, Ti (CxNy), x + y = 1, Ti (CxOy), x + y = 1, Ti (NxOy), x + y = 1, Ti (CxNyOz), x + y + z = 1. It was confirmed that one or more of these could be obtained, but all of these intermediate products were melted again using an electric furnace in a nitrogen-containing gas atmosphere such as N ₂ gas, reduced, and nitrided. For example, it was recognized that ingot-like TiN could be formed.

Example 2 10 kg of rutile sand and 3.4 kg of coke are thoroughly mixed. As in Example 1 above, this was placed directly into an arc-type electric furnace, heating conditions were set to around 3000℃, which exceeds the melting point of titanium nitride, and an AC voltage of 120V was applied to blow off the arc and oxidize. A titanium melt was produced (melting point: 1855°C). continue,
This melt was nitrided in an atmosphere of NH ₃ gas (flow rate 7.0/min) under the same heating temperature settings. At this time, the temperature of the molten body gradually rises as molten nitrides are generated, and molten nitrides are mixed with molten oxides along the way, and finally reaches a molten state at a temperature of around 3000℃. A certain fused nitride of titanium was obtained. When this is solidified, 6.2Kg (80% of the theoretical yield)
A titanium nitride ingot was obtained. This ingot-like titanium nitride was identified by powder X-ray diffraction.
It was only TiN. Also, chemical analysis shows that N
= 22.0%, and an ingot-like TiN having almost the same quality as a commercially available powder product was obtained.

Example 3 10 kg of rutile sand and 3.0 kg of coke are thoroughly mixed. As in Example 1 above, this was placed in a direct arc type electric furnace, the heating conditions were set to around 3000°C, which exceeds the melting point of titanium nitride, and an AC voltage of 120V was applied to blow the arc. A titanium oxide melt was produced (melting point: 1855°C). Next, this melt was treated with N ₂ gas (flow rate 4.5/min).
Nitriding was carried out under the same heating temperature setting conditions in a mixed gas atmosphere with NH ₃ gas (flow rate 1.0/min). At this time, as molten nitrides are formed, the temperature of the molten body gradually rises, and molten nitrides are mixed with molten oxides along the way, eventually reaching a molten state at a temperature of around 3000℃. A certain fused nitride of titanium was obtained. When this was solidified, 6.4 kg (83% of the theoretical yield) of titanium nitride ingots were obtained. This ingot-like titanium nitride was identified by powder X-ray diffraction.
It was only TiN. Also, chemical analysis shows that N
= 21.7%, and ingot-like TiN with almost the same quality as the commercially available powder product was obtained.

Example 4 10 kg of titanium carbide was directly charged into an electric arc furnace as in Example 1 above, and N ₂ was added as a pre-reaction.
gas (flow rate 2.5/min) and CO ₂ gas (flow rate 2.5/min)
/min) to generate titanium oxide. At this time, as titanium oxide was produced, it changed from a solid state to a molten state.
This is followed by N ₂ gas (flow rate 4.5/min) and NH ₃
As in Example 1 above, 4.0 kg of coke was charged in a mixed gas atmosphere with gas (flow rate 0.5/min).
The heating conditions were set to around 3000°C, which exceeds the melting point of titanium nitride, and an AC voltage of 120V was applied to blow the arc and nitride. As a result, ingot titanium nitride
8.1Kg (78% of theoretical yield) was obtained. This ingot-like titanium nitride was identified by powder X-ray diffraction.
It was only TiN. Also, chemical analysis shows that N
= 21.9%, and ingot-like TiN with almost the same quality as the commercially available powder product was obtained.

Example 5 10 kg of zirconium oxide and 2.1 kg of coke are thoroughly mixed. This was placed in an electric furnace in the same manner as in Example 1 above, and the melting point of zirconium nitride was exceeded.
Set heating conditions to around 3000℃, AC voltage 120V
energize to generate a molten material. Then to this melt
_N2 gas (flow rate 2.0/min) and _NH3 gas (flow rate 2.0/min)
/min) in a mixed gas atmosphere to obtain 7.0 kg (82% of the theoretical yield) of an ingot by nitriding and solidifying. When this ingot-like zirconium nitride was identified by powder X-ray diffraction, it was found to be only ZrN. In addition, chemical analysis showed that N = 12.4%, and powdered commercial product (N =
Ingot-like ZrN with almost the same quality as that of 12.6%) was obtained.

Example 6 10 kg of zirconium carbide was placed in the same electric furnace as in Example 1, and _N2 gas (flow rate
2.5/min) and CO ₂ gas (flow rate 2.5/min) was added to generate zirconium oxide. At this time, as zirconium oxide was produced, it changed from a solid state to a molten state.
This is followed by N ₂ gas (flow rate 1.0/min) and NH ₃
As in Example 5, 2.4 kg of coke was charged in a mixed gas atmosphere with gas (flow rate 3.0/min).
The heating conditions were set to around 3000°C, which exceeds the melting point of zirconium nitride, and electricity was applied at an AC voltage of 120V to nitride and solidify. As a result, 7.8 kg (76% of the theoretical yield) of ingot zirconium nitride was obtained. When this ingot-like zirconium nitride was identified by powder X-ray diffraction, it was found to be only ZrN. Further, chemical analysis showed that N=12.7%, and an ingot-like ZrN having almost the same quality as a commercially available powder product was obtained.

Example 7 10 kg of hafnium oxide and 1.2 kg of coke are thoroughly mixed. As in Example 1, this was directly placed in an arc type electric furnace, heating conditions were set to around 3500°C, which exceeds the melting point of hafnium nitride, and electricity was applied at an AC voltage of 120 V to produce a molten material. Next, this melt was heated under a mixed gas atmosphere of N ₂ gas (flow rate 0.5/min) and NH ₃ gas (flow rate 3.5/min).
Nitriding and solidifying the ingot into 7.4Kg (theoretical yield of 81
%)Obtained. When this ingot-like hafnium nitride was identified by powder X diffraction, it was found to be only HfN. Also,
Chemical analysis showed that N = 6.9%, and ingot-like HfN was obtained which had almost the same quality as the powdered commercial product (N = 7.0%).

Example 8 10 kg of hafnium carbide was placed in an electric furnace in the same manner as in Example 1, and N ₂ gas (flow rate 1.5
/min) and CO ₂ gas (flow rate 2.0/min) to generate hafnium oxide.
At this time, as hafnium oxide was produced, it changed from a solid state to a molten state. This was followed by N ₂ gas (flow rate 3.0/min) and NH ₃ gas (flow rate
1.0/min) in a mixed gas atmosphere
1.4 kg was put into the hafnium nitride, heating conditions were set at around 3500° C., which exceeds the melting point of hafnium nitride, and electricity was applied at an AC voltage of 120 V to nitride and solidify, as in the above example.
As a result, 8.0 kg (79% of the theoretical yield) of ingot hafnium nitride was obtained. When this hafnium nitride ingot was identified by powder X-ray diffraction, it was found to be only HfN. Further, chemical analysis showed that N=7.0%, and an ingot-like HfN having almost the same quality as a commercially available powder product was obtained.

[Effects of the Invention] As described above, according to the present invention, titanium group element nitrides can be obtained in the form of ingots at once and with good quality in the production reaction, and moreover, they can be actively molten in an electric arc furnace. However, since all processes can be carried out, it can be produced continuously and all at once at the minimum necessary heating temperature, making it possible to produce large quantities and large ingots, which is extremely superior in industrial productivity. Therefore, when used as abrasive grains for grinding, for example, there is no need for sintering as a separate process as in the past, and it can exhibit particularly remarkable effects in terms of productivity, workability, and economy.

This manufacturing method has extremely high technical value because it can be applied to various other uses in which it is necessary to obtain titanium group element nitrides in the form of ingots.

[Brief explanation of drawings]

The drawing is a principle diagram showing an example of an apparatus used when carrying out an example of the method according to the present invention.

Claims (1)

[Claims] 1. A reducing agent such as coke is added to powder of an oxide of a titanium group element (), and the mixture is heated in an electric arc furnace.
In an atmosphere of N ₂ , NH ₃ or a mixed gas thereof, the material is melted and nitrided by heating at least at a temperature higher than the melting point of the nitride of a titanium group element, and the resulting nitrided melt is solidified to form an ingot. A method for producing titanium group element nitride in the form of an ingot. 2. The method for producing an ingot-shaped titanium group element nitride according to claim 1, wherein the titanium group element compound () is selected from titanium oxide, zirconium oxide, and hafnium oxide. 3. A carbide powder of a titanium group element is oxidized by heating in an electric arc furnace in a mixed gas atmosphere of N ₂ and CO ₂ , and then this oxide of a titanium group element is oxidized with N ₂ , nitriding by heating and melting in an atmosphere of NH ₃ or a mixed gas thereof under heating conditions at least higher than the melting point of the nitride of a titanium group element;
A method for producing a titanium group element nitride in the form of an ingot, the method comprising solidifying the obtained nitrided melt to obtain an ingot.