JPH057351B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to inorganic compounds, such as No. 2 of the periodic table,
Forming of carbides, borides, silicides, sulfides, nitrides, oxides of 3rd, 4th, 5th, 6th and 7th period metals and their composite compounds or composites or intermetallic compounds with metals The present invention relates to a method for producing a molded body or a method for applying a thick coating of an inorganic compound to the surface of a metal molded body or a ceramic molded body.

Conventional technology Conventionally, carbides, borides, silicides, sulfides,
To produce compacts of nitrides, oxides, their composite compounds, or composites with metals or intermetallic compounds, first produce the inorganic compound powder that makes up the compact, and then hot-press or HIP the powder compact. Alternatively, production has been carried out by sintering in a high temperature furnace at normal pressure for a long time.

Methods for coating the surface of a metal or ceramic molded body with an inorganic compound include thermal spraying, CVD, and PVD. Although these methods are effective for coating thin films because it takes time to form a coating layer, they are not suitable from the viewpoint of work efficiency as coating techniques for thick walls of 1 mm or more.

In particular, recently, by locally igniting a powder mixture of metals and non-metals, the reaction propagates to the next layer of the mixture, allowing the synthesis reaction to progress in a self-propagating manner along the direction of pressure. An economical method has been proposed for simultaneously synthesizing and molding inorganic compounds or coating thick ceramics using a unidirectional pressure operation. (Japanese Patent Application No. 60-298619, Japanese Patent Application No. 60-298620) However, these methods can achieve efficient densification because the direction of propagation of the synthesis reaction and the direction of pressurization are almost the same. It is difficult to synthesize or coat the materials, and it is also difficult to synthesize and mold complex shapes. That is, it is necessary to simultaneously ignite over a wide area, or to perform multi-point ignition or multi-wire ignition to the extent that it does not interfere with compaction.

Problems to be Solved by the Invention The purpose of the present invention is to propagate the synthesis reaction in a direction substantially perpendicular to the direction of pressure applied over a wide area, and to perform densification under sequential isostatic pressure to form a dense molded product in the form of a plate or tube. The object of the present invention is to provide a method for obtaining a thick coating of an inorganic compound on the surface of a metal molded body or a ceramic molded body.

Means for Solving the Problems According to the method of the present invention, a powder mixture of metal and non-metal is first inserted into a metal container, the inside of the container is evacuated or replaced with a reactive gas such as nitrogen or oxygen, and then ignited. After being sealed together with the jig, it is held in a pressurized medium. Next, by locally igniting the powder mixture of metal and non-metal, the synthesis reaction progresses in a self-propagating manner in a direction perpendicular to the direction of pressure under conditions where the reaction further propagates to the next layer of the mixture. At the same time, an inorganic compound molded body is obtained, or a metal or ceramic molded body to be coated is sealed together with the powder mixture in a sealed metal container, and ignited and synthesized under pressure. In order to prevent the metal sealed container from melting due to the reaction heat generated at this time and preventing appropriate compression pressure from acting, the wall thickness of the metal sealed container is appropriately thick, and it also dissipates heat. To achieve this, it is necessary to select a material with good thermal conductivity. Copper or a copper alloy is preferable as such a metal. In addition, water, oil, molten salt, or a low melting point metal with good thermal conductivity is used as the pressurizing medium so as not to melt the metal in the sealed container. It is desirable that these pressurizing media be selected appropriately depending on the environmental temperature of the reaction system, the material and thickness of the sealed container, etc.

Furthermore, it is important to ensure that the volumetric shrinkage that accompanies the progress of synthesis is compensated for by the expansion of the gas that is in pressure equilibrium with the liquid as the pressure medium, so that almost no pressure drop occurs.

The pressure vessel used in the method of the present invention may be a liquid pressurized autoclave as shown in Fig. 1 connected to an accumulator for pressure prevention, or a gas pressurized autoclave as shown in Fig. 2. A type of high pressure vessel such as HIP can be used. When it is necessary to raise the environmental temperature of the reaction system, pressurization with liquid metal can be achieved by heating a container containing a low melting point metal in HIP.

As mentioned above, the characteristics of the method of the present invention are that it provides a method that enables synthesis over a wide area by propagating the synthesis reaction almost orthogonally to the direction of pressurization, and that it also allows synthesis over a wide area. By using a liquid as a pressurizing medium, the heat generated by the reaction is absorbed and dissipated into the liquid, making it possible to efficiently mold or coat inorganic compounds.

According to the method of the present invention, the direction in which the reaction progresses and the direction in which compressive pressure is applied are macroscopically orthogonal in most cases, but locally the reaction propagation speed is close to the liquid that is the pressurizing medium. is slower and relatively faster in the center of the powder mixture. Therefore, it is considered that locally the direction in which the reaction progresses and the direction in which pressure is applied are almost the same, so that efficient densification and molding can be carried out.

Effects of the Invention According to the method of the present invention, the synthesis reaction can be propagated over a wide area, and since a liquid capable of isotropic pressurization is used as a pressurizing medium, an inorganic material can be formed into an arbitrary curved surface shape. Molded bodies of the compound can be produced or coated. Such technology can be expected to have a wide range of applications; for example, it is possible to manufacture gas turbine blades with thick ceramic coatings, and to manufacture materials with complex shapes such as ceramic tubes or plates, and the method of the present invention is extremely practical. It is excellent.

Examples Next, the present invention will be explained in more detail with reference to Examples.

Example 1 A mixed powder made by thoroughly mixing titanium and boron powder at a molar ratio of 11:9 was filled into a copper container with a wall thickness of 1 mm to a thickness of 2 mm, and an ignition jig (2 mm) was placed at the end of the container.
A platinum wire with a diameter of 1 mm was welded to the end of a copper wire) and then vacuum sealed. Next, connect the accumulator and insert the copper container into a pressurized container filled with water as a pressurizing medium.
A current was instantaneously passed through the ignition jig under a pressure of 25 MPa to ignite and start the reaction. After the reaction was completed, the pressure inside the pressurized container was removed and the copper container was taken out to complete the production of the TiB-Ti composite molded body. The structure of the compact was densified, and a plate-shaped compact with a porosity of 3% was obtained.

Example 2 A mixed powder in which titanium and boron powders were sufficiently mixed at a molar ratio of 1:2 was filled in a copper container with a wall thickness of 2 mm, and an ignition jig was placed at the end of the container. It was sealed under vacuum. Next, at the same time as Example 1, the above copper container was inserted into a pressurized container, and at room temperature,
The synthesis was carried out under a pressure of 25 MPa to obtain a plate-shaped TiB ₂ molded body.

Example 3 A mixed powder made by thoroughly mixing titanium and carbon powder at a molar ratio of 1:1 was filled in a copper container with a wall thickness of 1 mm to a thickness of 3 mm, and an ignition jig was placed at the end of the container. It was sealed under vacuum. Next, as in Example 1, the above copper container was inserted into a pressurized container and heated to 300°C.
The synthesis was carried out under a pressure of 25 MPa to obtain a plate-shaped TiC molded body.

Example 4 A mixed powder made by thoroughly mixing zirconium and boron powders at a molar ratio of 1:2 was filled in a copper container with a wall thickness of 2 mm to a thickness of 2 mm, and an ignition jig was placed at the end of the container. It was sealed under vacuum. Next, Example 1
In the same manner as above, the above copper container was inserted into a pressurized container, and synthesis was performed at room temperature and under pressure of 25 MPa to obtain a plate-shaped ZrB ₂ molded body.

Example 5 A mixed powder made by thoroughly mixing titanium and sodium azide (NaN ₃ ) powder at a molar ratio of 3:1 was filled in a copper container with a wall thickness of 1 mm to a thickness of 2 mm in N ₂ gas. Then, it was sealed with an ignition jig placed at its end. Next, the copper container was inserted into a pressurized container in the same manner as in Example 1, and synthesis was performed at room temperature and under a pressure of 25 MPa to obtain a plate-shaped TiN molded body.

Example 6 Titanium, boron, and carbon powders in a molar ratio of 3:4:
A 2 mm thick copper container was filled with the mixed powder sufficiently mixed at a ratio of 1:1, and vacuum sealed with an ignition jig placed at the end of the container. Next, as in Example 1, the above copper container was inserted into a pressurized container, and synthesis was performed at room temperature and under a pressure of 25 MPa to form a plate-shaped
A TiB ₂ -TiC composite molded body was obtained.

Example 7 A mixed powder containing titanium and boron powder at a molar ratio of 1:2 and copper powder at 40% by weight was filled in a copper container with a wall thickness of 1 mm to a thickness of 2 mm, The tube was vacuum sealed with an ignition jig placed at its end. Next, the copper container was inserted into a pressurized container in the same manner as in Example 1, and synthesis was performed at room temperature and under a pressure of 25 MPa to obtain a plate-shaped TiB ₂ -Cu composite molded body.

Example 8 Nickel and aluminum powder in a molar ratio of 1:1
A 3 mm thick copper container with a wall thickness of 1 mm was filled with the mixed powder sufficiently mixed at the ratio of 3 mm, and the container was vacuum sealed with an ignition jig placed at the end. Next, as in Example 1, insert the copper container into a pressurized container,
Synthesis is carried out at 300℃ and under a pressure of 25MPa to form a plate-shaped
A NiAl molded body was obtained.

Example 9 A titanium plate with a thickness of 1 mm was inserted into a copper container with a wall thickness of 1 mm. Furthermore, a mixed powder made by sufficiently mixing titanium and boron powder at a molar ratio of 1:2 was filled on both sides of the titanium plate to a thickness of 2 mm, and the titanium plate was sealed in vacuum with an ignition jig placed at the end. . As in Example 1, the above-mentioned copper container was inserted into a pressurized container, and synthesis was performed at room temperature and under a pressure of 25 MPa. In this way, a plate-shaped molded body was obtained, in which a titanium plate was used as a core material and TiB ₂ was firmly coated thereon.

Example 10 A copper plate with a thickness of 1 mm was inserted into a copper container with a wall thickness of 1 mm. Furthermore, titanium and boron powders are added in a molar ratio of 1:2.
A well-mixed powder mixture was filled on both sides of a copper plate to a thickness of 2 mm, and vacuum sealed with an ignition jig placed at the end. The above copper container was inserted into a pressurized container in the same manner as in Example 1, and the temperature was 25 MPa at room temperature.
The synthesis was carried out under the pressure of In this way, a plate-shaped molded body was obtained, in which a copper plate was used as a core material and TiB ₂ was firmly coated thereon.

Example 11 A titanium plate with a thickness of 1 mm was inserted into a copper container with a wall thickness of 1 mm. Furthermore, titanium and carbon powder were added in a molar ratio of 1:
A mixed powder sufficiently mixed at a ratio of 1:1 was filled on both sides of a titanium plate to a thickness of 2 mm, and the titanium plate was vacuum-sealed with an ignition jig placed at the end. As in Example 1, the above copper container was inserted into a pressurized container and heated at 300°C.
The synthesis was carried out under a pressure of 25 MPa. In this way, a plate-shaped molded body was obtained, in which a titanium plate was used as a core material and TiC was firmly coated thereon.

Example 12 A 1 mm thick zirconium plate was inserted into a 1 mm thick copper container. Furthermore, a mixed powder made by sufficiently mixing zirconium and boron powder at a molar ratio of 1:2 was filled into one side of the zirconium plate to a thickness of 2 mm, and an ignition jig was placed at the end of the zirconium plate, which was then vacuum sealed. did. As in Example 1, the above-mentioned copper container was inserted into a pressurized container, and synthesis was performed at room temperature and under a pressure of 25 MPa. In this way, on the zirconium plate
A plate-shaped molded body strongly coated with ZrB ₂ was obtained.

Example 13 A 1 mm thick niobium plate was inserted into a 1 mm thick copper container. Furthermore, niobium and boron powders were added in a molar ratio of 1:
One side of a niobium plate was filled with a mixed powder sufficiently mixed at a ratio of 2 mm to a thickness of 2 mm, and the niobium plate was vacuum-sealed with an ignition jig placed at the end. As in Example 1, the above copper container was inserted into a pressurized container and heated to room temperature.
The synthesis was carried out under a pressure of 25 MPa. In this way, a plate-shaped molded article was obtained in which NbB ₂ was firmly coated on the niobium plate.

[Brief explanation of the drawing]

Figures 1 and 2 show an apparatus for producing a molded article of an inorganic compound by the method of the present invention, and Figures 3 and 4 show a thick coating of an inorganic compound using the same apparatus. It shows the method. Reference numeral 1 in these figures indicates a pressure vessel;
2 is a heating temperature raising device, 3 is an ignition device, 4 is a pressurizing pump, 5 is an archulator, 6 is a liquid pressure medium,
7 is a gas pressure medium, 8 is a metal sealed container, 9
is a mixed powder raw material, 10 is an ignition jig, 11 is a conducting wire,
Reference numeral 12 indicates a container for containing liquid, and 13 indicates a molded object to be coated.

Claims (1)

[Claims] 1. A powder mixture of metal and non-metal is inserted into a metal container, the inside of the container is evacuated or replaced with a reactive gas, and the mixture is sealed together with an ignition jig. By locally igniting the powder mixture in the high-pressure liquid while preventing a drop in pressure by using a liquid that is in pressure equilibrium with A method for producing an inorganic compound molded body by simultaneously and efficiently synthesizing and molding a molded body. 2. Insert the metal molded object or ceramic molded object to be coated into a metal container together with a powder mixture of metal and non-metal placed on its surface, evacuate the inside of the container or replace it with a reactive gas, and use an ignition jig. After encapsulating the powder mixture with the gas, the powder mixture is locally ignited in the high-pressure liquid, using a liquid that is in pressure equilibrium with the gas as the pressurizing medium to prevent a drop in pressure, and the synthesis reaction is carried out in a self-propagating manner in the pressurizing direction. A method of efficiently applying a thick coating of an inorganic compound to the surface of a metal molded body or ceramic molded body at the same time as the synthesis of the inorganic compound.