JPS63274665A - Polycrystalline ceramics having plastic deformability - Google Patents

Abstract

PURPOSE:To provide polycrystalline ceramics which has excellent heat resistance, oxidation resistance and corrosion resistance and is useful for mechanical parts, sealing materials, etc., by consisting the same of Ti3SiC2 single phase and providing plastic deformability at an ordinary temp. CONSTITUTION:Reactive gases consisting of >=1 kinds among chloride of Ti such as TiCl4, halide of Si such as SiCl4, halogenated hydride such as SiHCl3, and halogenated hydrocarbon such as Si(CH3)4 and >=1 kinds among halide of carbon such as CCl4, hydride such as CH4 and halogenated hydride such as CH3F are introduced into a reaction furnace of a CVD synthesis method. The reaction furnace is then heated to 1,200-1,400 deg.C and the total pressure of the reactive gases is regulated to 1-760Torr. The plastically deformable polycrystalline ceramics which consists of the Ti3SiC2 single phase and is coated with the metals, inorg. compds. or the composite thereof having 100g-800kg/ mm<2> measured load of Vickers hardness at an ordinary temp. and >=1,000 deg.C m.p. on the surface of the carbon base body is thus produced.

Description

[Detailed Description of the Invention] [Industrial Application Field] Ceramics generally have higher hardness than metal materials, and are superior in corrosion resistance and wear resistance, but are brittle and exhibit a cracked shape at room temperature. For this reason, compared to metal materials, there are greater restrictions on their use as mechanical parts and structural materials, and they are used as tool materials and I/O materials.
Only a very limited number of substrates such as C substrates are used.

The present invention relates to a new polycrystalline ceramic material that significantly improves the brittleness of conventional ceramic materials in that they break at the slightest deformation, and has plastic deformability even at room temperature.

The ceramics of the present invention are not only used as a single material for various mechanical parts, containers, molds, and sealing materials that require heat resistance, corrosion resistance, and oxidation resistance, but also as coatings on the surfaces of other materials. It can also be used for similar purposes. In particular, it is suitable for mechanical parts, sealing materials, etc. that need to be used in close contact with a mating material because it has a characteristic that it is difficult to break due to mechanical deformation.

[Conventional technology]

Among conventional ceramic materials, hexagonal BN is a typical material that has characteristics such as corrosion resistance and oxidation resistance and has low hardness. Hexagonal BN has a layered structure similar to graphite, and is also used as a solid lubricant. However, hexagonal BN has too low hardness (Hv100 or less) to be used as mechanical parts. Other low hardness ceramics include sulfides, Se compounds, etc.
These are inferior in terms of corrosion resistance and oxidation resistance.

The polycrystalline ceramic made of Ti-5iC= of the present invention has a hardness comparable to that of steel, and has the characteristics of a ceramic having excellent corrosion resistance and oxidation resistance.

Regarding this TiaSICz, Jeitschk has already
o and Nowotny (11, Jeitschko an
d H, Nowotny, Mh, Chem, 9
8.

329 (1967) and N1ckl1 etc. (J, J N
1ckj! , K., Schweitgerand
P, Luxenburg J, Less-Comm.
on 14 etals, 26°335 (1972
) has been used to synthesize small single crystals of several tens of micrometers.

However, until now, polycrystalline ceramics consisting essentially only of Tl5S+C2 phases have not been synthesized, and their properties have not been sufficiently measured.

[Problem that the invention seeks to solve]

The present invention aims to significantly improve the brittleness of conventional ceramic materials and to provide a material that has the characteristics of ceramics, such as corrosion resistance and oxidation resistance.

In addition, in order to use it as a mechanical part, it must be possible to produce a polycrystalline material with a certain size, rather than a fine single crystal.

[Means for solving problems]

The present inventors have been conducting research on synthesizing 5iC-TiC composite ceramics by the CVD method.

In the CVD method, the pressure inside the reactor is maintained at 1 to 760 Torr, and Ti chloride (Tici, etc.), Si halide (S+Cj!<, 5AP4, etc.), hydride (Si
n, etc.), hydrogen halides (SiHCls, 5i
HBrs etc.), and hydrogen halides (Si(C1
ls)-1CHsSiCj! -, etc.) and carbon halides (CCj!n), hydrides (CH,
, C2L, CI, etc.) and hydrogen halides (
CH, Cl, C1, P, etc.) and a reaction gas consisting of hydrogen, or a reaction gas consisting of T1 chloride, a halogenated carbohydrate of Si, and hydrogen, and 10
5i-Ti-C on the substrate heated to 00~1700℃
Various compounds of the system or mixtures thereof can be synthesized. Such compounds are TiC, 5iCTisiz
, Ti5SiCz, etc.

Composite ceramics consisting of various co-precipitates depending on the synthesis conditions, for example TiC+ Ti3SiC*, SiC
+ Ti5SiCa.

SiC+Ti5iz is obtained.

The inventors investigated various synthesis conditions and found that the polycrystalline ceramic of the present invention consisting of a Ti=SiCz single phase could be obtained. In addition, the hardness of this ceramic is determined by TiC, SiC, a mixture thereof, or even T
It was confirmed that it has significantly lower hardness and plastic deformability even at room temperature, compared to i5is and those made of a mixed phase containing T+sS+C2, TiC, and SiC, which have high hardness.

In order to obtain a polycrystalline material consisting of substantially single-phase Ti-5iC-, it is essential to select the CVD reaction conditions within an appropriate range. This will be explained below using examples.

Example 1 5i (Jn, TiC1<, CC1a
, and H.

Using gas. Graphite was used as the substrate, and the reaction temperature was set to 1.
The temperature was changed to 200-1600℃, H, gas and [C14
The flow rates of S+CC/(S+ cji! 4+TiC) were kept at 1800 and 17.5cj/win, respectively.
1-) Experiments were conducted by changing the ratio in the range of 0 to 1. The total pressure of the gas in the furnace was kept constant at 300 Torr.

The synthesis time is 2 hours.

FIG. 1 shows the results of identifying a Si-Ti-C compound synthesized on a graphite substrate by X-ray diffraction.

Under this experimental condition, the substrate temperature and the SiC1
A polycrystalline body consisting of a Ti-5iC- single phase was obtained only in the ratio range of a/(S+CI!a+T+C1a>.Substrate temperature 1300℃5IC1s/(SiCj!
The size of the polycrystal obtained with a + TiC1a) = 0.42 was 60alX40m5X0141.

Furthermore, the lattice constants determined by X-ray diffraction were a hexagonal compound with a=3.064 and C=17.650. The density according to Archimedes method is 4.
It is 53g/cat. Furthermore, from the X-ray diffraction intensity ratio, the C-axis of this polycrystalline body is parallel to the substrate, and (11
It is clear that tl exhibits a strong orientation in the 0-plane). The hardness of the above polycrystalline body was measured using a Vickers hardness tester at a load of 500.
It is a very soft polycrystalline material with HV = 600 kg/1 m2 when measured in g.

Furthermore, many slip lines were observed around the Vickers indentation, indicating that this polycrystalline body has excellent plastic deformability.

Example 2 5IJ4 a! produced by hot pressing. A bottle with a tip radius of 511IIl was used as the substrate, the same raw material gas as in Example 1 was used, the total gas pressure was 100 Torr, the substrate @ 1250°C Si C1a / (Si C1a
+T+c1a) = 0.3 for 30 minutes. Note that the flow rate ratio of Ccl</Hz was set to 0.01.

Si, N, Ti with a film thickness of 20 μm on the bottle, 5icj'-
A coating layer consisting of a single phase was obtained.

For comparison, the Ccla/Hx flow rate ratio is set to 0.05,
The coating layer was otherwise formed under the same conditions. The film in this case was found to be composed of a mixture of SiC and TiC as a result of X-ray diffraction.

When the Vickers hardness of both was measured, it was found that the film thickness of the Ti3SiCz film of the present invention was 7ookg/llll.
112te, and the comparative material showed an extremely high value of 3.000kg/ll1ts2.

Circumferential speed of MIJs'A disk 50o/sin'? '
The coated bottle was pressed against the disk with a load of 100 g and held for 5 minutes. T+s of the present invention
Si3N coated with S+c1z, film and M, 0. No changes in the disc were observed.

On the other hand, the comparative material had peeling of the film at the contact point, and A1.
0. A striation was seen on the disc. From this, especially in mechanical parts where ceramics come in contact with each other and slide, or when the mating material is a metal such as hardened steel, I! When the polycrystalline ceramic of the present invention is used as a moving member, it will not damage the mating material, and since it has high plastic deformability, stress concentration will be alleviated by deformation when uneven contact pressure is applied.
It can be seen that the material itself has excellent properties such as not being brittle.

〔Effect of the invention〕

The biggest drawback of conventional ceramics is their brittleness.

When using ceramics as mechanical parts or structural materials,
Because it has more hardness than necessary, it has poor workability, and when used as a sliding material, it damages the mating material, which limits its use.

The ceramics of the present invention solve all of these drawbacks of conventional ceramics, and have excellent plastic deformability and hardness equivalent to that of hardened steel, so they are less likely to damage the mating material. has been reduced to Furthermore, even at high temperatures, the surface has T+0. By forming a stable oxide film such as SiOt, it has the characteristics of ceramics compared to metal materials, such as heat resistance, oxidation resistance, and corrosion resistance.

As mentioned above, the polycrystalline ceramic according to the present invention is
It is suitable for a wide range of applications, such as mechanical parts, corrosion-resistant containers, and structural materials, which could not be used with conventional ceramics.

[Brief explanation of drawings]

FIG. 1 shows the relationship between generated phases and synthesis conditions determined by X-ray diffraction, a so-called CVD phase diagram. In addition, 5icjl! 4/ (SiC14+TiCj!<)
indicates the raw material gas flow rate ratio. Figure 1 S. Si + 'C procedural amendment June 2, 1988 Patent Application No. 108468 2, name of invention Polycrystalline ceramics having plastic deformability 3, case with the person making the amendment Related Patent Application Personnel Office
5-15 Kitahama, Higashi-ku, Osaka Name (213) Sumitomo Electric Industries, Ltd. President Satoshi Kawakami Department 4, Representative Address Inside Sumitomo Electric Industries, Ltd., 1-1-3 Shimaya, Konohana-ku, Osaka (Telephone number) 06-461-1031) Name (7881) Patent Attorney Senior Tetsu Manager:
5. Date of the amendment order 6. The subject of the amendment in the specification, the column for the title of the invention, the column for the description, the column for the detailed description of the invention, and the power of attorney. 7. The content of the correction has been corrected to “polycrystalline ceramics.” (4=) In ms, page 5, lines 4-5, r The present inventors have conducted -m-. ” to be deleted. ('L) Submit three copies of the power of attorney as shown in the attached sheet.

Claims (6)

[Claims] (1) A polycrystalline ceramic consisting essentially of a single phase of Ti_3SiC_2 and having plastic deformability at room temperature. (2) The polycrystalline ceramic according to claim (1), characterized in that the Vickers hardness at room temperature is 800 kg/mm^2 or less at a measurement load of 100 g or more. (3) Claims (1) and (2) characterized in that a metal, an inorganic compound, or a composite thereof having a melting point of 1000°C or higher is coated on the surface of a carbon substrate.
) The polycrystalline ceramics described in section 2. (4) One or more of Ti chloride, Si halide, hydride, and halogenated hydrohydride, and one or more of carbon halides, hydrides, and halogenated hydrohydride or a chloride of Ti and a halogenated hydrohydride of Si,
Claims (1) and (2) characterized in that the compound is synthesized by a CVD method using a reaction gas consisting of hydrogen.
), the polycrystalline ceramics described in (3). (5) Claims (1) and (2), characterized in that the C-axis direction of the crystal is selectively oriented perpendicular to the strain direction;
The polycrystalline ceramics described in (3) and (4). (6) SiCl_4, TiCl_4, C as raw material gas
Using Cl_4 and H_2 gas, the synthesis temperature is 1200~
Claims (1) and (2) characterized in that the synthesis is performed at 1400°C and a total reaction gas pressure of 1 to 760 Torr.
, (3), (4), and the polycrystalline ceramics described in (5).