JPS60200862A - Manufacture of sintered body constituting titanium nitride on surface and titanium nitride oxide in inside - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a sintered body whose surface layer is made of titanium nitride and whose interior is made of titanium oxynitride.

Nitrides of group IVa and Va group metals, ie, titanium nitride, zirconium nitride, hafnium nitride, niobium nitride, etc., are high hardness compounds with excellent heat resistance and corrosion resistance, and have a beautiful golden luster. Furthermore, since these compounds have electrical conductivity, it is difficult for lumps and the like to adhere to them. Therefore, it has extremely excellent properties as a guide member for winding up films or magnetic tapes, a kite member when manufacturing synthetic fibers, films, etc., and is also useful for decorative purposes.

Among these compounds, titanium nitride is the most commonly used because it has a low specific gravity and is relatively inexpensive.

Sintered bodies of titanium nitride have conventionally been produced by reducing and nitriding a powder of a mixture of titanium dioxide and a carbon material in a nitrogen atmosphere, compression molding the powder, and molding the powder in a vacuum or in an argon atmosphere. 1300-15 in active atmosphere
Manufactured by sintering at 00°C. However, the titanium nitride powder obtained by the above method has a coarse particle size, requires a long time for sintering, and moreover, it is impossible to obtain a dense sintered body. If sintering is performed at a higher temperature in an attempt to obtain a dense sintered body, denitrification will occur.

Therefore, coating titanium nitride on the surface of sintered bodies of other compounds has been carried out, but this has the disadvantage that the titanium nitride coating is easily separated from the base material, and there are also problems with the strength of the coating itself. There is.

The present invention aims to improve the above-mentioned drawbacks, and according to the method of the present invention, titanium dioxide powder is reacted with ammonia gas in a temperature range of 700 to 1000°C, and the resulting titanium oxynitride powder is compression molded. 1200-1700℃
By sintering in an ammonia atmosphere at a temperature range of , a sintered body is obtained in which only the surface layer is made of titanium nitride and the inside is made of titanium oxynitride.

In an ammonia atmosphere, titanium dioxide powder was
By heating to 0 to 100°C, titanium dioxide is reduced and nitrided to obtain titanium oxynitride powder. Sintering hardly occurs in this temperature range, so if fine titanium dioxide powder is used as a raw material, fine titanium oxynitride can be obtained as is.

When the titanium oxynitride powder obtained in this way is compression molded and sintered in an ammonia atmosphere, only the surface layer is nitrided and reduced, resulting in a sintered body whose surface is titanium nitride and the inside remains titanium oxynitride. Since fine titanium oxynitride powder is used as the sintering raw material, a dense sintered body can be obtained in a short time. Furthermore, the bond between the titanium nitride layer and the titanium oxynitride inside is strong.

The present invention will be specifically explained below.

Titanium dioxide, which is a raw material for titanium oxynitride, may be manufactured by any method, but in order to obtain fine titanium oxynitride powder, it is necessary to use titanium dioxide powder as fine as possible. The reaction between titanium dioxide powder and ammonia is carried out at a temperature range of 700-1000°C for over 1 hour. If the temperature is less than 700°C, the reaction rate is insufficient and a large amount of unreacted titanium dioxide remains, making it unsuitable as a raw material for obtaining a high-strength sintered body. 1 000 again
If the temperature exceeds 0, bonding of particles occurs and the resulting titanium oxynitride powder becomes coarse, making it similarly unsuitable as a sintering raw material.

The titanium oxynitride powder obtained as described above is compression molded into a desired shape. At this time, PVA as a binder,
Adding a small amount of a caking substance (sizing agent) such as CMC or PVP increases the strength of the green compact and makes it easier to handle. Although the pressing pressure is not particularly limited, the higher the pressing pressure, the thinner the titanium nitride layer becomes.

This green compact was heated to 1200 to 1700 in an ammonia atmosphere.
Sinter in the temperature range of °C. At this time, it is also possible to control the thickness of the titanium nitride layer by diluting the ammonia gas with an inert gas such as nitrogen or argon.

The reason for limiting the sintering temperature to 1200-1700'C is
If the temperature is less than 1200°C, no matter how long the sintering time is, the density will not decrease and a sintered body with sufficient hardness will not be obtained. Furthermore, even if sintering is performed at a temperature exceeding 1,700'C, not only will the sintering time not be shortened, but denitrification will begin to occur, making it impossible to obtain a dense sintered body. Further, the temperature increase rate until reaching the sintering temperature is desirably 500° C./hr or less. 5
If the temperature is increased at a rate exceeding 00°C/hr, cracks may occur or the titanium nitride layer on the surface may peel off.

In this way, a dense sintered body whose interior is made of titanium oxynitride and whose surface layer is made of titanium nitride can be easily obtained.

Note that the amount of oxygen in the titanium oxynitride inside can be controlled by adjusting the temperature and reaction time when titanium dioxide powder is reacted with ammonia.

Next, the present invention will be specifically explained with reference to Examples.

Powder 2.0 obtained by reacting titanium dioxide with an average particle size of 0.03 g in an ammonia atmosphere under the conditions shown in Table 1.
g was compression molded into a cylindrical shape with a diameter of 10) and sintered. The properties of the produced sintered body are also listed in the same table.

Samples manufactured under conditions other than those of the present invention are also shown in the same table.

It is difficult to obtain titanium nitride powder with a diameter of less than 1.0 mm, and when a sintered body is made using powder with this particle size, the density of the sintered body will be low even if a press pressure of 2 tons is used. It is 96.8% or less.

Patent Applicant Mitsubishi Metals Co., Ltd. Agent Patent Attorney Masahiro Matsui Procedural Amendment June 11, 1985 Manabu Shiga, Commissioner of the Japan Patent Office Indication of the Case 1982 Patent Application No. 057443 2 Name of the Invention Surface is nitrided Method for producing a sintered body made of titanium with a titanium oxynitride interior 3 Relationship with the amended case Name of patent applicant (82G) Mitsubishi Metals Co., Ltd. 4 Agent (164) Address 1 Honmachi, Nakano-ku, Tokyo Chome 31-4 No. 5 Date of amendment order Voluntary action 6 Number of inventions to be increased by amendment None 7 Subject of amendment Scope of claims in the specification, each column of detailed explanation of the invention 8 Contents of amendment As shown in the attached sheet Specification amend the claims as follows.

1. Pressure mold the titanium oxynitride powder to 1200~
A method for producing a sintered body in which only the surface layer is made of titanium nitride and the inside is made of titanium oxynitride, which is sintered in an ammonia atmosphere in a temperature range of 1700°C.

2 The titanium oxynitride powder contains 70% of the titanium dioxide powder.
The manufacturing method according to claim 1, which is obtained by reacting with ammonia gas in a temperature range of 0 to 1000°C. Town II The description of the detailed description of the invention in the specification is corrected as follows.

1. The statement "Titanium dioxide powder can be obtained" from line 12 to line 14 of page 3 is deleted.

2 Change the description “700 to 100°C” on page 3, line 20 to I
'700~1000'Cj,! l: Correct.

3 The statement on page 4, line 9: “The sintered body remains as it is.”
is corrected as ``It remains as it is, and becomes a sintered body in which titanium nitride gradually changes to titanium oxynitride from the surface layer to the inside.

4. The statement from page 5, line 15 to line 16 of the same page, ``Dilute ammonia gas with an inert gas such as nitrogen or argon,'' is 1. Dilute ammonia gas with a rare gas such as argon.j
I am corrected.

5 Page 7, Table 1, description in the sintering atmosphere column rNH380
% 10 N220z, NH350%” N250%
J to FNH380% + Ar 20%, NH3
50% +Ar501 j Correct.

Claims (1)

[Claims] 1. Reacting titanium dioxide powder with ammonia gas at a temperature range of 700 to 1000°C, compression molding the obtained titanium oxynitride powder, and sintering it in an ammonia atmosphere at a temperature range of 1200 to 1700°C. A method for producing a sintered body in which only the surface layer is made of titanium nitride and the inside is made of titanium oxynitride.