JPS6212669A - Sintered body whose surface is titanium oxide and inside is titanium oxynitirde - 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 <Industrial Application Field> The present invention relates to a sintered body whose surface layer is made of titanium nitride and whose interior is made of titanium oxynitride.

<Prior art and its problems> 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.

It has 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 and magnetic tapes, and as a guide member when manufacturing synthetic fibers, films, etc.

It is also useful for decoration.

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. 1700 in active atmosphere
Manufactured by sintering at high temperatures above ℃. 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.

In an attempt to obtain a dense sintered body, if sintering is carried out at very high temperatures, denitrification will occur.

Therefore, coating the surface of sintered bodies of other compounds with titanium nitride has also been practiced.

Another drawback is that the titanium nitride coating tends to peel off from the base material, and there is also a problem with the strength of the coating itself.

<Structure of the Invention> The present invention solves the above conventional problems. According to the present invention, the second surface layer is mainly made of titanium nitride, and the nitrogen content gradually decreases from the surface layer to the inside. On the other hand, a sintered body with an increased oxygen content and a titanium oxynitride interior is provided.

The surface layer of the sintered body of the present invention is titanium nitride.

The interior is titanium oxynitride, and between the titanium nitride layer on the 9 surface and the titanium oxynitride layer inside, there is an intermediate layer in which the nitrogen content decreases while the oxygen content increases as you go from the 1 surface to the inside. do. That is, the sintered body of the present invention has a gradual double structure in which the intermediate layer is interposed between the titanium nitride layer on the surface and the titanium oxynitride layer inside. The nitrogen content and oxygen content of the surface layer and internal layer are shown in the following table, respectively.

Since the sintered body of the present invention has a composition in which the nitrogen content and oxygen content gradually change from the surface to the inside, the sintered body has a nitrided surface compared to the conventional one whose surface is coated with titanium nitride. The bond between the titanium layer and the internal titanium oxynitride layer is extremely strong. Furthermore, the density of the sintered body is also significantly higher. Incidentally, the conventional sintered body made by compression molding and sintering titanium nitride powder has a Vickers hardness of 800 to 1500, which is 9/9
About mze.

While the density is about 90 to 97 inches, the sintered body of the present invention has a Vickers hardness and a density of 1700 to 18 inches, respectively.
50kg/mm+981 or more, which is denser and stronger than conventional sintered bodies. Further, while the conductivity of the conventional sintered body is about 1×10 −′fLcR, the sintered body of the present invention has excellent conductivity of 1 to 5×10−” fLcR.

Next, the above sintered body is obtained by compression molding titanium oxynitride powder.
It is obtained by sintering in a nitrogen or ammonia atmosphere at a temperature range of 200 to 1700°C. The raw material titanium oxynitride powder is titanium dioxide powder 700 to 1
Preferably, it is obtained by reacting with ammonia gas in a temperature range of 1,000°C. When titanium dioxide powder is heated in the temperature range of 700-1000°C in an ammonia atmosphere.

Titanium dioxide is reduced and nitrided to obtain titanium oxynitride powder. Almost no sintering occurs in this temperature range, so
When fine titanium dioxide powder is used as a raw material, titanium oxynitride as fine as that amount can be obtained.

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 in a temperature range of 700 to 1000°C for 1 hour or more. If the temperature is less than 700°C, the reaction rate is not sufficient and a large amount of unreacted titanium dioxide remains, making it unsuitable as a raw material for obtaining a high-strength sintered body. Further, at temperatures exceeding 1000° C., particle bonding 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. Press pressure is not particularly limited.

The green compact is heated in an ammonia or nitrogen atmosphere for 12 hours.
Sinter at a temperature range of 00 to 1700°C.

The reason for limiting the sintering temperature to 1200 to 1700°C is 1.
If the temperature is less than 200°C, no matter how long the sintering time is, the density will not increase and a sintered body with sufficient hardness will not be obtained. Also 1
Sintering at a temperature exceeding 700° C. not only does not shorten the sintering time, but also causes denitrification to occur, making it impossible to obtain a dense sintered body. It is desirable that the temperature increase rate to reach the Maniwa sintering temperature is 500° C./hr or less. 500℃/h
If the temperature is increased at a rate exceeding r, cracks may occur or the titanium nitride layer on the surface may peel off.

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.

Furthermore, when the green compact is fired in an ammonia or nitrogen atmosphere, the thickness of the titanium nitride layer on the surface can be controlled by mixing ammonia or an inert gas containing less than 50vol% nitrogen or hydrogen gas. still.

When obtaining titanium oxynitride powder, if the reaction between titanium dioxide and ammonia is not sufficient, titanium dioxide may remain on the surface of the sintered body, but if the oxygen content in one surface layer is less than 40%, the hardness will decrease. There is no problem as it may have a negative impact on the

In this case, a small amount of titanium dioxide also remains in the inner layer, but it has almost no effect.

By the above manufacturing method, a sintered body having a titanium nitride surface and a titanium oxynitride inside is obtained.

Since the sintered body of this method uses fine titanium oxynitride powder as the sintering raw material, a dense sintered body can be obtained in a short time.

<Examples and Comparative Examples> Example 1 Powder obtained by reacting titanium dioxide with an average particle size of 0.06μ in an ammonia atmosphere at a temperature of 800°C for 4 hours, granulated with 1% KPVA was added at 1t/d. A powder compact with a thickness of 8 fi was made using a mold of 50 x 501 m+ at a pressure of . The green compact was heated to 160℃ in an ammonia atmosphere.
After sintering at 0°C for 2 hours, a golden yellow sintered body was obtained.

The distance from the surface of this sintered body to 0.1 fl is 1.7
- from a titanium nitride layer mixed with Tie, k), Q,
The center of 3ws has an oxygen content of 8.2% and a nitrogen content of 16.7%.
It was formed by a layer having a composition of 75.1% titanium. The layer 0.1111 to 0.3111 from the surface was a titanium oxynitride layer in which the oxygen content gradually increased and the nitrogen content decreased. The Vickers hardness of this sintered body was 1830'Kg/mze.

Example 2 The same green compact as in Example 1 was heated at 1300°C in a nitrogen atmosphere for 3
The obtained sintered body was sintered for a time of 0.05 io+ from the surface.
(7) To? Ni Ro1 Teha4.0%f) Ti
The titanium nitride layer has a mixture of 0.01 and 0.01. '05～0
．． In the layer 2111, the oxygen content gradually increased and the nitrogen content decreased, and the center part from Q, 'lax was composed of a titanium oxynitride layer with an oxygen content of 8.0 cm and a nitrogen content of 17.0 cm. .

Example 3 of this sintered body The same titanium dioxide powder as in Example 1.2 was reacted at a temperature of 900° C. for 3 hours, and a powder was made into a green compact under the same conditions as in Example 1.2. This green compact was sintered at 1500° C. for 6 hours in an atmosphere in which nitrogen was diluted with 20vol% argon. This sintered body consists of a titanium nitride layer mixed with 2.3 inches of Tie from the surface to 0.07 fl, and the layer from 0.07 to 0.25 m gradually increases in oxygen content and nitrogen. content decreases.

From 0.25 fm, the oxygen content in the center is 8. (]4% nitrogen amount 1
It was formed of a 7.1-inch titanium oxynitride layer. The color tone of this sintered body was almost the same golden yellow as in Example 1.2, and the Vickers hardness was 1810/9/mm.

Comparative Example Titanium nitride powder with an average powder size of 1.0 μm was made into a compact under the same conditions as in the example and sintered at 1700° C. for 4 hours in a nitrogen atmosphere. The color tone of the obtained sintered body was dark red, and the Vickers hardness was 900.97 mm''.

Claims (1)

[Claims] 1. The surface layer is mainly made of titanium nitride, the nitrogen content gradually decreases from the surface layer to the inside, while the oxygen content increases, and the inside is made of titanium oxynitride and the surface is made of titanium nitride. A sintered body whose interior is made of titanium oxynitride. 2 The nitrogen content of the surface layer is 21% by weight or more, the internal oxygen content is 2 to 25% by weight, and the nitrogen content is 10 to 21% by weight.
% by weight of the sintered body of claim 1.