JPH0541593B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing a nitride ceramic molded body having an arbitrary shape, and particularly relates to a method for manufacturing a nitride ceramic molded body having an arbitrary shape, and particularly relates to a superconducting magnetic shielding plate, a superconductor element, a wear-resistant member, a heat-resistant The present invention relates to a method for producing a nitride ceramic molded body useful as a member, a corrosion-resistant member, a radiation-resistant member, a decorative member, a functionally graded material, and an intermediate layer bonding material for bonding ceramics and metals.

(Prior art and problems to be solved by the invention) In general, methods for manufacturing nitride ceramic compacts include sintering nitride ceramic powder, and depositing nitride ceramics on a substrate by physical vapor deposition or chemical vapor deposition. There is a way to do it. In the sintering method, it is generally difficult to obtain a dense molded body of nitride ceramics having a complicated curved surface or linear shape, and sintering requires a large amount of thermal energy and a long time. Further, the vapor deposition method requires a substrate on which the ceramics are deposited, and the adhesion between the deposited ceramics and the substrate is weak, and the thickness of the deposited film is limited to several μm or less.

Japanese Patent Publication No. 56-27441 describes nitrides, borides,
As a method for producing high melting point ceramic powder such as carbide, a combustion synthesis method that utilizes a combustion process due to an exothermic reaction during elemental combination has been disclosed. For example, in the case of nitrides, a metal powder serving as a raw material is placed in high-pressure nitrogen, and one end of the raw material is ignited with high heat to start a nitriding combustion reaction and obtain a nitride powder. This manufacturing method consumes substantially less energy and
Since the reaction proceeds at a speed of up to 15 cm/sec,
Although it has the advantage of significantly shortening the time required for production, it is limited to powders.

In view of the drawbacks of the above-mentioned nitride ceramic molded bodies manufactured by conventional methods, the present invention aims to form molded bodies having any shape such as a completely densified plate shape, a cylindrical shape, a linear shape, or even a complex curved surface or a polyhedron. This provides a method for synthesizing the body's energy efficiently and in an extremely short time (seconds).

(Means for Solving the Problems) The present invention arranges a combustion agent around a metal molded body having an arbitrary shape, and ignites one end of the combustion agent with ignition in a nitrogen-containing atmosphere to start a nitriding combustion reaction. This is a method for producing a nitride ceramic molded body having an arbitrary shape by instantaneously nitriding a metal molded body using the heat generated by this reaction.

The present invention will be described in more detail below with reference to FIG.

FIG. 1 is an example of an apparatus for implementing the present invention. This device includes a pressure vessel 5 having a nitrogen-containing gas supply pipe 4. A fireproof container 6 (crucible) is arranged inside the pressure container 5. A metal molded body 1 serving as a raw material is placed in the fireproof container 6, and a combustion agent 2 is placed around the metal molded body 1. Furthermore, an ignition heater 3 connected to a power source 7 installed outside the pressure vessel 5 is disposed above the fireproof vessel 6 . The nitriding combustion reaction is started by igniting the combustion agent 2 by the heater 3 in a nitrogen-containing atmosphere introduced into the pressure vessel 5. Generated by this nitriding combustion reaction
The raw metal molded body 1 is instantaneously nitrided by heat of 2000° C. or higher, and a nitride ceramic molded body having an arbitrary shape can be produced while the original shape of the metal molded body 1 is maintained.

Here, the metal molded body 1 has a plate shape, a cylindrical shape, a linear shape,
It has other arbitrary shapes, such as Nb,
Group b and b of the periodic table such as Ta, Ti, Zr, Hf, etc.
A material made of one of the group metals can be suitably used. Note that the molded body in the present invention is made of bulk metal, and is not intended to be a powder or a molded body obtained by compressing powder.

As the combustion agent 2, one that causes a nitriding combustion reaction is used. In the present invention, since the nitriding reaction of the raw metal molded body is accelerated by the high heat generated by the combustion agent 2, the same type of metal powder as the raw metal molded body can be used as long as it burns with sufficient heat generation. Alternatively, different metal powders may be used. For example, Si, Al, B, etc., which cause a strong nitriding combustion reaction in groups B and B of the periodic table, etc. In addition, an appropriate amount of the same nitride powder as the product, another high-melting point ceramic powder, or a different type of metal powder is added to the metal powder of the combustion agent to change the calorific value during the nitriding combustion reaction. It is effective to control the nitridation of The combustion agent after this reaction can be used as ceramic powder.

As the nitrogen-containing atmospheric gas, nitrogen gas, ammonia gas, or a compound that becomes a nitrogen-containing atmospheric gas by heating can be used. Further, it is sufficient that the pressure of the nitrogen-containing atmospheric gas is 1 atm or more and up to 100 atm, but by increasing the pressure even higher, it is possible to nitride the raw metal molded body to a thickness of several 100 μm or more. Furthermore, it is also possible to control the nitriding combustion reaction by mixing inert argon gas with the nitrogen-containing atmospheric gas, or to create a reducing atmosphere by mixing hydrogen gas.

(Function) By the method of the present invention, NbN having an arbitrary shape,
Nitride ceramic compacts such as TaN, TiN, ZrN, HfN, etc. can be produced by heat generation from a combustion agent. Furthermore, this manufacturing method produces nitride ceramic molded bodies in an extremely short time (seconds) with only a small amount of energy required for ignition, making this manufacturing method an unprecedented and revolutionary method. I can say it.

If the raw metal molded body is several hundred micrometers or less, the entire molded body will be the above-mentioned nitride ceramic molded body, and if it is thicker than that, the molded body will have a surface layer of several hundred μm composed of the above-mentioned nitride ceramic.

The nitrided part is a completely compact nitride ceramic in which nitride particles are tightly bonded. Therefore, the inherent properties of nitrides, such as wear resistance, corrosion resistance, and heat resistance, are fully exhibited. Furthermore, when only the surface layer of the metal compact is nitrided by the method of the present invention, the interface between the surface nitride ceramic layer and the metal compact is composed of a nitrogen diffusion layer, as shown in FIG. , the two are strongly connected.

(Example) Examples of the present invention will be described below. In each example, the reaction apparatus schematically shown in FIG. 1 was used.

Example 1 A commercially available Nb metal plate (3 cm in diameter, 100 μm in thickness) was embedded in a combustion agent filled in a porous graphite crucible, and this was placed in a pressure vessel. The combustion agent was a mixture of commercially available Nb and NbN at a molar ratio of 17:3, and the amount was 150 g. Next, after vacuum degassing the inside of the pressure vessel, nitrogen gas was introduced to 100 atm, and the upper part of the combustion agent was heated with a heater (60A, 3
The nitriding combustion reaction was started. The reaction ended after 4 seconds.

The raw material Nb metal plate has a B1 type crystal structure.
It was completely converted to NbN ceramics, with no shape change or cracks. The structure of the NbN plate material was completely a dense NbN polycrystalline aggregate structure. Note that similar results were obtained at a nitrogen pressure of 50 atm.

The superconducting transition temperature of the obtained NbN plate material was measured and found to be 16.4K.

Example 2 A nitriding combustion reaction was performed on a 1 mm thick Nb metal plate in the same manner as in Example 1. the result,
The Nb metal plate was nitrided to a surface layer of 200 μm to form a NbN layer. In this case, the layer from the surface to a thickness of 100 μm was B1-phase NbN, and the nitrogen content inside had a gradient concentration composition that decreased with distance from the surface of the metal compact due to diffusion.

Example 3 A nitriding combustion reaction was carried out in the same manner as in Example 1 on a Nb metal pipe with a thickness of 200 μm and an outer diameter of 1 cm and a Nb coil wire with a diameter of 200 μm. As a result, B1 type NbN pipes and coil wires were obtained, and no deformation was observed.

Example 4 A nitriding combustion reaction was performed on a Ti metal plate having a thickness of 100 μm in the same manner as in Example 1. however,
In this example, commercially available Ti powder and TiN were used as combustion agents.
A mixture of powders at a molar ratio of 1:2 was placed around the Ti metal plate. As a result, a plate material was obtained in which the surface layer was nitrided with cubic TiN up to a depth of 10 μm.

Example 5 A nitriding combustion reaction was performed on a Ta metal plate having a thickness of 20 μm in the same manner as in Example 1. However, in this example, a mixture of commercially available Ta powder and TaN powder at a molar ratio of 3:2 was used as the combustion agent. As a result, a slightly brittle but completely nitrided TaN plate was obtained. The crystal phase of TaN was a mixture of cubic and hexagonal crystals.

Example 6 A nitriding combustion reaction was performed on a Zr metal plate having a thickness of 60 μm in the same manner as in Example 1. For combustion agents
A mixed powder of Nb powder and NbN powder was used. As a result, a completely nitrided cubic ZrN plate was obtained.

Example 7 A nitriding combustion reaction was performed on a 60 μm thick Hf metal plate in the same manner as in Example 6. the result,
A completely nitrided cubic HfN plate was obtained.

(Effect of the invention) As explained above, by the method of the present invention,
Nitride ceramics having an arbitrary shape can be obtained by effectively and quickly nitriding a metal molded body having an arbitrary shape in a nitrogen-containing atmosphere. This nitride ceramic molded body can be industrially applied as a superconducting magnetic shielding plate, a superconductor element, a wear-resistant member, a corrosion-resistant member, a radiation-resistant member, a decorative member, etc.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of an apparatus for carrying out the method of the present invention. FIG. 2 shows the state of the metal when only the surface layer of the metal molded body is nitrided according to the present invention.
FIG. 3 is a diagram conceptually showing the nitridation rate at the nitride layer interface. 1... Metal molded body, 2... Combustion agent, 3... Ignition heater, 4... Nitrogen-containing gas supply pipe, 5...
Pressure vessel, 6... Fireproof vessel.

Claims (1)

[Claims] 1. Metal powder serving as a combustion agent is placed around a metal molded body having an arbitrary shape, and one end of the combustion agent is ignited with ignition in a nitrogen-containing atmosphere to start a nitriding combustion reaction, A method for producing a nitride ceramic molded body having an arbitrary shape, characterized in that the metal molded body is nitrided in a short time by the heat generated by this reaction. 2. The method for producing a nitride ceramic molded body having an arbitrary shape according to claim 1, wherein the metal molded body serving as a raw material is made of one or more metals of group b and group b of the periodic table. 3. The method for producing a nitride ceramic molded body having an arbitrary shape according to claim 1, wherein the combustion agent is a powder of one or more metals of group B and group B of the periodic table. 4. The nitriding reaction of the metal molded body is controlled by adding at least one kind of nitride powder of Group B and Group B metals of the periodic table to the combustion agent and controlling the calorific value of the combustion agent. A method for producing a nitride ceramic molded body having an arbitrary shape according to claim 1. 5. The method for producing a nitride ceramic molded body having an arbitrary shape according to claim 1, wherein the combustion agent contains powder of an element that causes a strong nitriding combustion reaction in groups B and B of the periodic table. 6. The method for producing a nitride ceramic molded body having an arbitrary shape according to claim 1, wherein the pressure of the nitrogen-containing atmosphere is 1.0 atm or more. 7. The method for producing a nitride ceramic molded body having an arbitrary shape according to claim 1, wherein the nitrogen-containing atmosphere uses at least one of nitrogen gas, ammonia gas, or a compound that becomes a nitrogen-containing atmosphere gas when heated.