JPH0699215B2 - Method for producing transition metal carbide single crystal - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a transition metal carbide single crystal with few dislocations and sub-microcrystals by a floating zone method.

(Prior Art and Problems Thereof) Transition metal carbides have high hardness and have been used for various applications. For example, various cutting tools as cermets, wear-resistant parts and the like can be mentioned. Also,
It is said to be useful as an electronic component such as a feed emitter.

The following method is generally well known as a method for growing a single crystal of the transition metal carbide.

(1) A floating zone method in which a rod-shaped sintered body of a transition metal carbide is heated and melted while the sintered body is moved to grow a single crystal.

(2) A flux method in which a mixture of a flux such as nickel and a transition metal carbide is heated to grow a single crystal in the flux.

In particular, in order to obtain a large single crystal of transition metal carbide,
The method of (1) is adopted (Journal of Less Comm
on Metal, 1981, 82, 63). However, when a single crystal is grown by this method, sub crystallites whose growth directions are different by several tens of minutes may be generated. If there are sub-microcrystals that differ by several tens of minutes at this angle, the usable area of the single crystal is extremely small.

Therefore, the probability of a method for producing a transition metal carbide single crystal with few dislocations and sub-microcrystals with high reproducibility is desired.

(Technical Means for Solving Problems) As a result of earnest research for solving the steam problem, the present inventors have found that when a single crystal is manufactured by the floating zone method, a rod-shaped sintered body and It was found that by controlling the oxygen content of the grown single crystal, a uniform large single crystal with few dislocations and sub-microcrystals can be obtained with good reproducibility.

The present invention relates to a floating zone method for producing a single crystal by moving a rod-shaped sintered body while heating and melting a part of the rod-shaped sintered body, wherein the rod-shaped sintered body having an oxygen content of 0.10 to 0.50%. Using a body, while heating and melting a part of the rod-shaped sintered body under an inert gas atmosphere of 2 to 100 atmospheres, a transition characterized by growing a single crystal having an oxygen content of 0.03 to 0.10% The present invention relates to a method for producing a metal carbide single crystal.

Examples of the transition metal carbide in the present invention include NaCl
-Type crystal structure TiC, ZrC, VC, NbC, HfC and TaC
Can be mentioned.

In the present invention, the rod-shaped sintered body 3A and 3B made of the transition metal carbide having an oxygen content of 0.10 to 0.50% is used,
Oxygen content is 0.03 to 0.10%, and it is possible to grow a large single crystal of a transition metal carbide that is uniform and has few dislocations and sub-microcrystals. In order to produce the rod-shaped sintered body having an oxygen content of 0.10 to 0.50%, based on the oxygen content of the transition metal carbide powder as a raw material for producing the sintered body, under reduced pressure, 1500 to 2200. The sintering temperature and time of the rod-shaped molded body made of a transition metal carbide are appropriately selected within the range of 10 to 120 minutes.

The floating zone method adopted in the embodiment of the present invention will be described based on the apparatus and manufacturing conceptual diagram shown in FIGS. 1 and 2.

In FIG. 1, rod-shaped sintered bodies 3A and 3B are supported by a holder 2 attached to a shaft 1 in a container kept under an inert gas atmosphere. Rod-shaped sintered bodies 3A and 3B
A graphite disc 4 for controlling the melt zone composition is sandwiched between
3A end of the contact surface with the graphite disk 4 and the graphite disk 4
Is heated and melted by induction heating with the high frequency generated from the high frequency coil 5.

As shown in FIG. 2, a rod-shaped single crystal 7 is formed with the melting zone 6 between the rod-shaped sintered bodies 3A and 3B. This rod-shaped single crystal 7 is a rod-shaped sintered body 3A held by a holder 2.
And 3B can be grown by slowly moving downwards.

The moving speed of the holder 2 is preferably 3 to 30 mm / hour.

When the single crystal is grown, the upper and lower shafts 1 are rotated to mix and stir the melt zone, thereby facilitating the growth of the single crystal.

The growth of the single crystal is preferably performed in an inert gas atmosphere of 2 to 100 atm, and examples of the inert gas include helium, argon, neon, nitrogen and a mixture thereof.

(Examples) Examples of the present invention will be shown below.

Example 1 After mixing TiC powder and graphite powder having an oxygen content of 0.662%, the mixture was molded into two types of cylinders having a diameter of 12 mm, lengths of 130 mm and 50 mm, and further rubber press-molded. The two types of cylinders were sintered in vacuum at 1800 ° C for 30 minutes and the oxygen content was reduced to 0.
183%, rod-shaped sintered body 3A with different C / Ti atomic ratio of 0.99
And got 3B.

The longer rod-shaped sintered body 3A is on the upper side and the shorter rod-shaped sintered body 3B is on the lower side, and is supported by the holder 2, and the contact surface of both sintered bodies has a thickness of 1 m
I sandwiched m graphite disks.

In the helium gas atmosphere with a total pressure of 8 atm, the melting zone 6 is formed by heating the contact portion of the rod-shaped sintered body 3A, the graphite disk and the rod-shaped sintered body 3B by high frequency heating, and the melting zone 6 is 6 mm / hour It was rotated at 5 rpm while moving downward with.

The rod-shaped sintered body 3A gradually melted into the melting zone 6, and at the lower part of the melting zone 6, oxygen content was 0.035% and C / Ti atomic ratio was 0.96.
iC single crystal was grown.

When the (100) plane was cut out from the vicinity of the terminal end of the obtained single crystal ingot having a diameter of 10.5 mm and a length of 60 mm and analyzed, there was no sub-crystallite whose growth orientation differed by several tens of minutes.

Example 2 NbC powder having an oxygen content of 0.524% was used to manufacture rod-shaped sintered bodies 3A and 3B having an oxygen content of 0.205% at a sintering temperature of 2000 ° C. for 30 minutes.

In a helium gas atmosphere with a total pressure of 15 atm, as in Example 1.
A single crystal of NbC was grown. The oxygen content of the obtained single crystal was 0.059%, and no sub-fine crystal was present.

Example 3 ZrC powder having an oxygen content of 0.341% was used to manufacture rod-shaped sintered bodies 3A and 3B having an oxygen content of 0.158% at a sintering temperature of 2000 ° C. for 30 minutes.

In a helium gas atmosphere with a total pressure of 10 atm, as in Example 1.
A single crystal of ZrC was grown. The oxygen content of the obtained single crystal was 0.033%, and no sub-fine crystal was present.

Comparative Example 1 When the temperature during sintering was set to 1600 ° C. in Example 1, rod-shaped sintered bodies 3A and 3B having an oxygen content of 0.555% were obtained. When single crystals were grown from these rod-shaped sintered bodies, TiC single crystals with an oxygen content of 0.117% were obtained, and there were 10 sub-microcrystals whose growth directions differed by several tens of minutes.

Comparative Example 2 When the sintering temperature was set to 2000 ° C. in Example 1, rod-shaped sintered bodies 3A and 3B having an oxygen content of 0.057% were obtained. When a single crystal was grown from these rod-shaped sintered bodies, a TiC single crystal with an oxygen content of 0.002% was obtained, and there were 6 sub-microcrystals whose growth directions differed by several tens of minutes.

[Brief description of drawings]

FIG. 1 and FIG. 2 are conceptual diagrams showing an apparatus and production in the production of a single crystal by the floating zone method. 1 is a shaft, 2 is a holder, 3A is a rod-shaped sintered body, 3B is a rod-shaped sintered body, 4 is a graphite disk for controlling the composition of the melting zone, 5 is a high frequency coil, 6 is a melting zone, and 7 is a rod-shaped single crystal.

Claims (1)

[Claims] 1. A floating zone method for producing a single crystal by moving a sintered rod-shaped body while heating and melting a part thereof to obtain a rod-shaped sintered body having an oxygen content of 0.10 to 0.50%. Used, while heating and melting a part of the rod-shaped sintered body under an inert gas atmosphere of 2 to 100 atm, the oxygen content is 0.
A method for producing a transition metal carbide single crystal, which comprises growing a single crystal in an amount of 03 to 0.10%.