JPH0753605B2 - Method for manufacturing titanium nitride sintered body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a method for producing a titanium nitride sintered body having a sufficient golden luster.

[Conventional technology / problems] It is known that transition metal nitrides such as titanium nitride and zirconium nitride give a beautiful golden color when they are densely sintered, and are expected to be used for decorative members. Has been done.

However, it is very difficult to sinter titanium nitride, zirconium nitride, etc. by themselves. For example, in order to sinter titanium nitride powder raw material to produce a sintered body, a special apparatus such as a hot press machine is required. However, it is difficult to obtain a dense sintered body even with such an apparatus. Further, considering the maintenance of the hot press machine and the life of the mold material such as carbon mold to be used, it is economically extremely disadvantageous and impractical. In the hot press method,
Carbon is impregnated into the sintered body from the shape material such as the carbon mold used, resulting in darkened "dullness" on the surface of the sintered body, making it difficult to obtain a sintered body with a beautiful golden color. Since it is difficult to manufacture a complex shaped product that is required in particular, it cannot be said that the hot pressing method is remarkably unsuitable as a method for manufacturing a decorative ceramics sintered body.

Therefore, in order to obtain a high-density sintered body, a low-melting-point metal such as Fe, Co, Cr, or Ni is added to titanium nitride raw material powder or zirconium nitride raw material powder and sintered. By using this method, a dense sintered body can be obtained at a relatively low sintering temperature, but a dull glossy surface remains even by advanced polishing, and it is difficult to obtain a polished surface having sufficient glossiness. There has been a problem that the corrosion of the metal components present in the sintered body progresses and, for example, due to seawater, sweat, acid rain, etc., the color changes, and the color tone suitable as a decorative member is impaired.

An object of the present invention is to obtain a method for producing a titanium nitride-based sintered body that exhibits a beautiful golden color with sufficient luster and has high hardness and excellent corrosion resistance.

[Means for Solving Problems] As a result of intensive studies conducted by the present inventors in view of the above problems, as a result, various oxide powders were added as a sintering aid to titanium nitride raw material powder at a specific ratio. The present invention has been completed by finding that a titanium nitride-based sintered body that is sufficiently dense and has a beautiful golden color can be obtained by sintering after molding without using a hot pressing method.

That is, according to the present invention, the titanium nitride raw material powder is selected from the group consisting of titanium oxide, niobium oxide, tantalum oxide, molybdenum oxide, tungsten oxide, yttrium oxide, and lanthanide-based rare earth oxides as a sintering aid.
1 to 1850 in a non-oxidizing atmosphere or vacuum by pressure molding a mixture containing 0.5 to 10% by weight of one or more kinds.
Another object of the present invention is to provide a method for producing a titanium nitride-based sintered body, which is characterized by sintering at a temperature of ° C.

[Operation] According to the method of the present invention, the titanium nitride-based sintered body is prepared by using titanium nitride raw material powder, titanium oxide, niobium oxide, tantalum oxide,
It can be obtained by adding and sintering one or more oxide sintering aids selected from oxides of molybdenum oxide, tungsten oxide, yttrium oxide, and lanthanide-based rare earth elements. The amount of the binder added is in the range of 0.5 to 10% by weight, preferably 3 to 7% by weight. If the amount added is less than 0.5% by weight, a sufficiently dense sintered body cannot be obtained, the hardness is low, and a polished surface having sufficient gloss cannot be obtained. On the other hand, if the addition amount exceeds 10% by weight, a dense sintered body having gloss can be obtained, but a vivid golden color cannot be obtained and the hardness becomes low, which is not preferable.

The particle size of the titanium nitride raw material powder used in the method of the present invention is 10
It is not particularly limited as long as it is 5 μm or less, but 5 μm
It is preferable to use a titanium nitride raw material powder having a particle size of m or less. The particle size of the oxide sintering aid may be 5 μm or less, preferably 2 μm or less for any oxide.

By pressure-molding a mixture obtained by adding an oxide sintering aid to the titanium nitride raw material powder in the above-mentioned ratio, and sintering at a temperature of 1600 to 1850 ° C in a non-oxidizing atmosphere such as nitrogen or argon or in a vacuum. A titanium nitride sintered body having a beautiful golden color can be easily obtained. The sintering time is usually 30 minutes to 5 hours, although it depends on the sintering temperature and the like.

[Example] Example A titanium nitride raw material powder having an average particle size of 1.3 μm was used, and an average particle size of 0.0
5 to 1.0 μm of various oxide sintering aids described in Table 1 below were blended, then ethanol was added and mixed in a wet ball mill for 21 hours. Ethanol is evaporated and dried from the obtained mixed powder, and then pressure-molded at a pressure of 2 ton / cm ² , and 1500 to 18
Atmosphere firing at a temperature of 50 ° C and 1 atmosphere of nitrogen gas
I went on time.

The titanium nitride-based sintered body thus obtained was mirror-polished and tested for color tone, corrosion resistance, Vickers hardness (Hv), sintered body density and corrosion resistance. The results obtained are listed in Table 1.

Here, the sintered body density is measured by the Archimedes method and is shown as a relative value to the theoretical density. In the corrosion resistance test, a sample subjected to mirror polishing was immersed in seawater to observe discoloration. In Table 1, the circle marks in the results of the corrosion resistance test indicate the state in which no discoloration was observed, and the x mark indicates that discoloration was observed.

As shown in Table 1, experiment numbers 1 and 2 (comparative example)
Is a low-density porous body due to poor sintering, a mirror surface could not be obtained even by mirror polishing, and the hardness was low. In Experiment No. 23 (Comparative Example), Co and Ni were used as sintering aids, the polished surface was poor in gloss, and as a result of the corrosion resistance test, the polished surface was significantly impaired. Experiment number 6
7 and 7 (comparative examples) were added with an oxide sintering aid in an amount outside the range of the present invention, and had a difficulty in the color tone of the polished surface, and the hardness was low.

Experiment Nos. 3 to 5 and 8 to 22 are examples of the present invention, and all the titanium nitride sintered bodies exhibited a beautiful golden color with sufficient gloss and were excellent in hardness and corrosion resistance.

[Advantages of the Invention] By adding the above-mentioned oxide sintering aid to the titanium nitride raw material powder, a titanium nitride material having excellent properties can be obtained without using an economically disadvantageous special device such as hot pressing. A sintered body can be obtained.

The titanium nitride-based sintered body obtained by the method of the present invention has a beautiful color tone rich in luster, and has high hardness and excellent scratch resistance, so that it can be used for decoration of accessories, exterior parts for watches, tableware, etc. It can be used as a member. In addition to its beautiful color tone, it also has excellent corrosion resistance,
It can also be used for construction materials such as decorative tiles, sanitary ware, and fishing tackles. Further, in addition to having high hardness, it is expected to be used as a wear-resistant sliding member such as a roller and a mechanical seal because it has excellent heat conductivity as an inherent property of titanium nitride.

Claims (2)

[Claims] 1. A raw material powder of titanium nitride selected from the group consisting of titanium oxide, niobium oxide, tantalum oxide, molybdenum oxide, tungsten oxide, yttrium oxide, and oxides of lanthanide-based rare earth elements as a sintering aid. Alternatively, pressurize a mixture containing 0.5 to 10% by weight of two or more kinds, and press at 1600 to 1850 ° C in a non-oxidizing atmosphere or vacuum.
A method for producing a titanium nitride-based sintered body, which comprises sintering at a temperature of. 2. The manufacturing method according to claim 1, wherein the non-oxidizing atmosphere is a nitrogen or argon atmosphere.