JPS62227005A - Ceramic molding and its production - Google Patents

Abstract

PURPOSE:To easily produce a wear-resistant ceramic molding having high strength and high toughness by packing a mixture composed of excess metallic powder and B powder into a casting mold and coating the surface thereof with the B powder of the amt. equiv. to the amt. of the metallic powder, then igniting the bottom of the casting mold. CONSTITUTION:The mixture contg. the metallic powder of the group IVA or VA of periodic table and B powder at the ratio at which the former is stoichiometrically excessive is packed into the casting mold. Said mixture is further coated thereon with the mixture layer contg. the above-mentioned metal and the B powder at the ratio at which the latter is incorporated approximately at the stoichiometric amt. The part near the inside bottom of the casting mold is then ignited to progress an exothermic reaction while pressing from above in a vacuum. The ceramic molding formed with the wear-resistant hard ceramic layer which is integrally bound with the base body and does not exfoliate on the surface of the base body consisting of the boride of the above-mentioned metal and the bond metal or the alloy and having the high strength and high toughness is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a ceramic molded body having an integrally bonded hard surface layer and a method for producing the same. More specifically, the present invention provides high strength and high toughness materials suitable for cutting tools and wear-resistant materials. The present invention relates to a novel structure in which a hard ceramic layer is integrally formed on the surface of a molded body made of a boride-metal composite material, and a method for producing this structure by simple means using a simple device.

BACKGROUND ART Conventionally, as a method for manufacturing a molded body having a hard layer on the surface, for example, CVD, PvD, etc. are applied to the surface of a base made of metal.
A method of coating a hard ceramic layer by a method such as a metal coating method or a thermal spraying method, or a method of hardening the metal surface by a carburizing treatment, a nitriding treatment, etc. are known.

However, the conventional method of forming a hard layer using a coating method has the disadvantage that the hard layer easily peels off due to the difference in thermal stress between the hard layer and the base metal. In order to prevent this peeling, it is necessary to apply a coating consisting of multiple layers of different types, but this? Will doing so significantly complicate the manufacturing process and result in higher costs? I can't escape it.

On the other hand, although the method of completely hardening the metal surface by carburizing or nitriding can reduce the cost compared to the coating method described above, it has the disadvantage of not being able to obtain a sufficiently hard material. .

Problems to be Solved by the Invention The purpose of the present invention is to improve the drawbacks of such a conventional molded product on the surface of the hard layer 2, and to create a material with high strength and high toughness suitable for cutting tools and wear-resistant materials. It is an object of the present invention to provide a novel ceramic molded body having a hard surface layer which is integrally bonded to a base and does not peel off.

Means for Solving All Problems The present inventor has conducted extensive research to develop a ceramic molded body that has both high strength and high toughness and has a hard layer on its surface that does not peel off. The present invention has been based on the discovery that all of the above objects can be achieved by integrally forming a hard ceramic layer on the surface of a substrate made of metal borides bonded with metals or alloys. It's arrived.

That is, the present invention provides a hard ceramic layer on the surface of a substrate consisting of a boride of at least one metal selected from Groups IVA and VA of the periodic table and a bonding metal or alloy. The present invention provides an integrally formed ceramic molded body.

The molded article of the present invention is made of at least one boride selected from metals belonging to Groups IVA and VA of the periodic table, ie, titanium, zirconium, hafnium, niobium, and tantalum. , borides bonded with bonding metals or alloys.
It has a structure in which the entire base is made of metal composite material and a hard ceramic layer is provided on the surface portion. The bonding metal used as a component of the above-mentioned boride is the metal from the ninth periodic table IV.
It is easier to manufacture using metals from Groups A and VA, or metals from Group IB of the periodic table that do not produce borides when reacted with boron, such as copper, gold, silver, or alloys thereof. It is advantageous in this respect.

The composition of this substrate is 50 to 50% metal boride.
A range of 99% by weight and 50-1% by weight of the bonding metal or alloy is preferred.

The hard ceramic layer provided on the surface of the substrate may be a hard ceramic such as a metal nitride, carbide, boride, or oxide itself, or a hard material powder such as a metal compound of these metals, boron carbide, silicon carbide, or nitride. Ceramics containing dispersed powders such as boron and diamond are also suitable.

Particularly preferred are layers composed of the metal borides themselves, which are constituents of the substrate.

This hard ceramic layer has at least one layer on the surface of the substrate.
It is sufficient to form it with a thickness of rrrln.

In the molded body of the present invention, it is necessary that the substrate made of the above-mentioned boride-metal composite material and the hard ceramic layer are integrally bonded, and such a molded body can be manufactured, for example, by the following method. can do.

That is, (A) powder of a metal belonging to Group IVA or Group VA of the periodic table and boron powder, which are necessary to generate the boride present in the substrate, are mixed so that the former is in stoichiometric excess. This mixture is mixed in a suitable proportion and filled into a mold, and then the surface r(B) of Group IVA or Group V of the periodic table is mixed.
After coating with a mixture of powder of a metal belonging to group A and boron powder in stoichiometric amounts or in a proportion in which the latter is in excess,
High heat is ignited near the bottom of the mold, and the exothermic reaction gradually propagates toward the top, producing boride and melting the metal. Does this reaction produce boride? In order to be sure and to make it dense, it is necessary to perform it under vacuum while applying pressure from above.

As a result of this reaction, a boride of a metal belonging to Group IVA or Group VA of the periodic table is generated in the base portion, and the excess metal is melted and the boride is fully bonded to form a boride-metal composite. Form. On the other hand, on the surface part,
A hard ceramic layer consisting exclusively of borides of the same metal is formed, which is integrally bonded to the base part.

In the above (A), instead of using an excess of a metal from Group IVA or Group VA of the periodic table as a binder, the excess metal is used as a binder. It is also possible to replace it with a metal that does not react with boron, such as a metal from group IB of the periodic table or an alloy thereof. Further, as a raw material for forming a hard ceramic layer, hard material powder such as B4C! is added to the mixture used in (A) above. , A.A.
20. , ZrO□, Tie, Sin.

It is also possible to use powders of cubic boron nitride, diamond, etc. added thereto. The blending ratio of this hard material powder is preferably in the range of 10 to 95% by weight.

It is necessary to carry out this method under pressure, and this pressurization is carried out by any means such as spring compression, hydraulic press, isostatic compression, etc., at a pressure of at least 50 Kg/ca. This pressurization is preferably carried out in such a manner that the pressure is applied parallel to the direction of progress of the exothermic reaction.

Next, ignition for starting the reaction can be performed by inserting an ignition jig, for example, two tungsten wires with platinum wire welded to the ends near the bottom of the mold, and passing an electric current through the jig.

In order to further ensure the densification of the hard ceramic layer in the molded article of the present invention, a heat absorbing plate such as a metal copper plate is placed on the surface of the raw material mixture (B) for forming the hard ceramic layer. During the reaction, it is desirable to fully promote endothermic cooling.

Does the molded article of the present invention have the shape of a mold? By selecting an appropriate material, it can be formed into any shape, such as a plate, rod, cylinder, cylinder, or block.

Effects of the Invention According to the present invention, a boride having high strength and high toughness is produced.
A ceramic molded body having a hard ceramic layer on the surface of a base made of a metal composite material can be manufactured using simple equipment and operations.

The ceramic molded body of the present invention is suitably used as, for example, a cutting tool or a wear-resistant material.

Example Next, is the present invention based on examples? This will be explained in more detail.

Example 1 A metal mold heat-insulated with graphite was placed in a container that could be depressurized, and the total molar ratio of titanium and boron powders was 11:
The container was filled with a mixed powder thoroughly mixed at a ratio of 9:9, and further filled with a mixed powder where titanium and boron powders were thoroughly mixed at a molar ratio of 1:2 to a thickness of about 2 cm.

Next, a metallic copper plate is brought into contact with the surface of the mixed powder layer with a molar ratio of titanium and boron of 1:2, and the top and bottom are aligned!
A pressure of 72001 f/d was applied to compress the spring and at the same time compaction was performed, and a current was instantaneously passed through the ignition jig (platinum wire with a diameter of 0.2 rrrm was fully welded to the ends of two tungsten wires). , the end of the mixed powder layer with a molar ratio of titanium and boron of 11=9 was ignited to start a reaction.

As the reaction progresses from the edge of the green compact, approximately 3000
In the combustion zone heated to K, the synthesis reaction of titanium boride and the melting of an excess amount of titanium occur, and densification progresses.
The contraction caused by the reaction is successively captured by the extension of the spring, and the pressure necessary for densification is continuously applied to the sample.

After the reaction was completed, the molded body was cooled and taken out from the mold. On the surface of the substrate made of TiB-Ti composite material,
Titanium diboride layer with excellent peeling resistance? A molded article having the following properties was obtained.

Example 2 Substrate? As a raw material composition for forming a hard layer, a mixed powder containing titanium powder and boron powder at a total molar ratio of 1:2 and a total of 3% by weight of copper powder was used. As a product, 50% by weight of B4C powder is added to the mixed powder? Using the blended mixed powder, a B4C dispersion layer with excellent peeling resistance was formed on the surface of a substrate made of a TiB2-Cu composite material in the same manner as in Example 1. Molded body with? Obtained.

Example 3 Substrate? As the raw material composition for forming the hard layer, a mixed powder containing zirconium powder and boron powder at a molar ratio of 1:1 is used, and as the raw material composition for forming the hard layer, zirconium powder and boron powder are used. Using a mixed powder containing a molar ratio of 1:2, a hard layer of ZrB with excellent peeling resistance was applied to the surface of a substrate made of a ZrB2-Zr composite material in the same manner as in Example 1. A molded body with gold was obtained.

Example 4 A mixed powder containing titanium powder and boron powder at a molar ratio of 11:9 was used as a raw material composition for forming the entire base, and as a raw material composition for forming a hard layer,
C! A mixed powder containing 20% by weight of BN (cubic boron nitride) powder? Using the same method as in Example 1, a molded article having a CBN dispersed layer with excellent peeling resistance on the surface of a substrate made of a TiB-Ti composite material was obtained.

Example 5 As a raw material composition for forming a substrate, a mixed powder containing niobium powder and boron powder at a molar ratio of 1:2 and a total of 3% by weight of copper powder was used to form a hard layer. Using a mixed powder of niobium powder and boron powder at a molar ratio of 1:2 as a raw material composition for the process, in the same manner as in Example 1, it was applied to the surface of a substrate made of Nt)B, -Cu composite material. A molded article having a NbB layer with excellent peeling resistance was obtained.

Example 6 A mixed powder containing tantalum powder and boron powder at a total molar ratio of 3:4 and 3% by weight of copper powder was used as a companion raw material composition for forming the base. A mixed powder gold layer with a molar ratio of tantalum powder and boron powder of 3:4 was used as the raw material composition for forming the hard layer, and a substrate made of Ta3B4-Cu composite material was prepared in the same manner as in Example 1. Ta and B4 layers with excellent peeling resistance on the surface? A molded article having the following properties was obtained.

Claims (1)

[Claims] 1. A hard ceramic layer is integrally formed on the surface of a substrate consisting of a boride of at least one metal selected from Groups IVA and VA of the periodic table and a bonding metal or alloy. ceramic molded body. 2. In the mold, (A) powder of at least one metal selected from Groups IVA and VA of the periodic table and boron powder are placed in a stoichiometric excess of the former during metal boride production. Fill with a mixture containing the following proportions, and then top it with (
B) after coating with a layer of a mixture containing a powder of at least one metal selected from Groups IVA and VA of the periodic table and boron powder in approximately stoichiometric proportions of the latter;
A boride of at least one metal selected from Groups IVA and VA of the periodic table, and a bonding metal or A method for manufacturing a ceramic molded body in which a hard ceramic layer is integrally formed on the surface of a base made of an alloy. 3. In a mold, (A) powder of at least one metal selected from Groups IVA and VA of the periodic table and boron powder are placed in a stoichiometric excess of the former during metal boride production. Fill with a mixture containing the following proportions, and then top it with (
B) After coating (A) with a layer of a mixture containing a component for forming hard ceramics, the inner bottom of the mold is ignited and an exothermic reaction proceeds while pressurizing from above under vacuum. A method for manufacturing a ceramic molded body, in which a hard ceramic layer is integrally formed on the surface of a substrate made of a boride of at least one metal selected from Group IVA and Group VA and a bonding metal or alloy. 4 In the mold, (A) powder of at least one metal selected from Groups IVA and VA of the periodic table;
A mixture containing powder of at least one metal selected from Group B and boron powder is filled, and the mixture is filled with (
B) After coating with a layer of a mixture of a powder of at least one metal selected from Groups IVA and VA of the periodic table and boron powder and a hard ceramic-forming component added,
A boride of at least one metal selected from Groups IVA and VA of the periodic table, and a bonding metal or A method for manufacturing a ceramic molded body in which a hard ceramic layer is integrally formed on the surface of a base made of an alloy.