JPH02129085A - Surface-treating method of zirconium oxide-and/or titanium oxide-containing shaped material - Google Patents

Abstract

PURPOSE:To form surface layer having excellent electric conductivity, wear resistance and adhesion on the surface of shaped material by bringing specific powder into contact with the surface of ZrO2- and/or TiO2-containing shaped material and heating in non-oxidizing atmosphere. CONSTITUTION:Sintering auxiliary such as Al2O3 or Y2O3, etc., is added to ZrO2 and/or TiO2 and shaped, then sintered to obtain ZrO2 and/or TiO2- containing shaped material. Next, the surface of said shaped material is coated with slurry containing one or more powders selected from B4C powder, B powder, BN powder and C-containing powder and heated at 1500-1800 deg.C in non- oxidizing atmosphere.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for surface treatment of molded bodies containing zirconium oxide and/or titanium oxide, and in particular, the present invention relates to a method for surface treatment of molded bodies containing zirconium oxide and/or titanium oxide, and in particular, zirconium oxide (Zr02) and titanium oxide (Ti), which are solid electrolytes.
02) has electrical conductivity on the surface of the sintered body containing
In addition, zirconium boride (ZrB2) has excellent abrasion resistance.
1. Zirconium nitride (ZrN), zirconium carbide (
ZrC), titanium nitride (TiB2), titanium nitride (T
The present invention relates to a method for forming a surface layer made of one or more of titanium carbide (TiC) and titanium carbide (TiC), which does not peel off from the base material.

[Conventional technology 1] On the surface of solid electrolyte zirconium oxide and titanium oxide,
Zr112. has excellent electrical conductivity and wear resistance. ZrN
, ZrC, TiB2. TiN.

A material with a TiC surface layer formed thereon is effective for electronic components such as oxygen sensors and structural materials utilizing wear resistance.

Conventionally, ZrB2. ZrN, ZrC, TiB2゜TiN,
As a method for forming a TiC surface layer.

[) (8-shot method 21CVD method This is how it is implemented.

The method of forming a surface layer by thermal spraying is a method in which a thermal spray material is heated above its melting point and then sprayed. The disadvantage of this method is that the sprayed material has a thermal expansion coefficient that is the same as that of the base material, so cracks occur during the process of rapid cooling from a high temperature, so adhesive strength cannot be expected at the interface between the base material and the surface layer. Therefore, the surface layer easily peels off from the material, so it cannot be used for wear-resistant materials, etc.

On the other hand, a method of forming a dense film using the CVD method is also effective, and the adhesion to the surface layer is strong. However, like the thermal spraying method, this method involves bonding different materials together;
At high temperatures, peeling easily occurs at the boundaries. Furthermore, the raw materials are expensive because of the gas phase synthesis, and the manufacturing equipment is more complicated than normal equipment as it requires treatment of wandering gas and the like, making it expensive.

In addition, various boronizing agents (for example, JP-A No. 48-40640, JP-A No. 51-2498
4, Japanese Unexamined Patent Publication No. 61-60876). However, these do not include those that target ceramics, and the processing conditions are low-temperature processing because they target metals.

[Problem to be Solved by the Invention 1] The present invention solves the problem that the 111 surface layer peels off at the boundary with the material, which is a fundamental drawback of the prior art.

(2) The surface layer formation cost is very high.

This is an attempt to solve two points.

[Means for Solving the Problems] In order to solve the above problems, the present invention uses ZrO2 and/or
Alternatively, a molded body containing T i O2 is coated with boron carbide (84G) powder, boron (B) powder, boron nitride (B) on its surface.
ZrB2. ZrN, ZrC, T
iB2.

Consisting of one or more of TiN and TiC,
The present invention provides a method for forming a surface layer that does not peel off from a base material.

[Operation 1] In order to increase the adhesion strength of the surface layer and prevent peeling due to the difference in thermal expansion coefficient between the two layers due to temperature rise, it is desirable that the two layers are bonded with a continuous composition. For this reason, bonding with distribution due to diffusion is ideal.

Furthermore, the cost of forming the surface layer can be reduced by bringing the raw material powder into contact with the surface of the molded body by coating or the like, and by using inexpensive raw materials.

The molded body containing ZrO2 and/or TiO2 in the present invention includes ZrO2 and/or TiO2.
For example, in addition to those consisting of Al2203. Y2O3
, Cab, MgO, and other sintering aids are also used, and green molded bodies are produced by press molding, rubber press molding, and slip cast molding of raw materials containing ZrO2 and/or TiO2, and green molded bodies. In other words, a calcined body or a sintered body that has been completely sintered is used. Regarding ZrO2, those toughened by Y2O3 etc. are promising as materials, and /l
! Partially stabilized zirconia, Zr02, may be used as a composite material with 203 or BN.
The i-mixture material is also included in the molded product of the present invention.

Methods for bringing the molded body into contact with the powder of the substance containing B4C, B, BNi5 and C include simply embedding it in the powder, preparing the powder into a slurry and using it as a coating agent, etc. Any method that allows contact may be used and is not particularly limited.

Heating is performed in a non-oxidizing atmosphere. When carried out in an oxidizing atmosphere, substances containing 84C, B, BN, and C become 700
The object of the present invention cannot be achieved due to oxidation from around .degree.

As a gas that creates a non-oxidizing atmosphere, N2゜Ar,)
12. CO and the like are used alone or in combination.

Note that it is preferable to use a reduced pressure atmosphere because a uniform film can be obtained, and a vacuum may also be used.

By heating ZrO2 and B4C, B or BN in a non-oxidizing atmosphere, each ZrB2
is generated.

ZrO2+B4C-*ZrB2+CO Z r O2+ B -Z r B 2 + 8
203Zr02+BN -ZrB2+B2O3+N
When 2ZrO2 and C are heated in a non-oxidizing atmosphere that does not contain N2, ZrC is produced by the following formula, and when heated in a non-oxidizing atmosphere containing N2, ZrC is produced by the following formula.
Generate rN.

ZrO2+C+N2→ZrN+C0 When two or more of B4C, B, BI15 and C are used as a mixture, a surface layer containing a product corresponding to the powder used is obtained.

Carbon black, tar, pitch, etc. are used as the C-containing substance.

Regarding the heating temperature, in order to maintain the toughness properties of 1 Partial Stabilization Z'02 as a base material, heating at a temperature of 1,600°C or higher will cause crystal grain growth and reduce the strength, so heating at high temperatures is not recommended. It is disadvantageous.

However, for materials that require spalling properties, such as Zr02-BN composite, the heating temperature is 1600℃.
As described above, it is necessary to change the heating temperature depending on the purpose, and the optimum temperature is in the range of 1500°C to 1800°C from the surface layer molding speed and strength.

The thickness of the surface layer generated at this time is about several tens of um,
It is firmly and uniformly bonded to the base material, and the interface is Z
rB2. Since ZrN and ZrC are continuously diffusion bonded to the base material, continuity of thermal expansion coefficients, etc. is maintained, and phenomena such as peeling do not occur at boundaries.

By heating TiO2 and B4C, B or BN in a non-oxidizing atmosphere, T i B
2 is generated.

T i 02 + 84 C-4T i B 2 +
C0Ti02+B-e TiB2+B203Ti0
2+BN-+ TiB2+B2O3+N2T i 0
When 2 and C are heated in a non-oxidizing atmosphere that does not contain N2, TiC is produced according to the following formula.

TiO2+C”　　　　Tic+c.

When heated in a non-oxidizing atmosphere containing N2, T
Generate iN.

TiO2+C+N2→TiN+(:Q When two or more of B4C, B, BN and C are used as a mixture, a surface layer containing a product corresponding to the powder used is obtained.

When investigating the heating temperature for surface layer formation using TiO2, 1
The optimum temperature was 500°C to 1800°C.

Since the surface layer generated at this time is attached to the base material at high temperature, it forms a strong diffusion layer and is stable.

[Example] Example 1 Partially stable type z "02 molded body (width 20 mm, thickness 30 mm
, length 40mm), ■ green molded body, ■ calcined body, ■
84C having an average particle size of 2.5 μm was dispersed in a 1% aqueous solution of an acrylic binder and applied to the surface of three types of sintered bodies to a thickness of 100 to 300 μm.

This sample was heated to 1600° C. at a heating rate of 2.5° C./ll1n in a N2 atmosphere of 5×10″″T o r r and held for 2 hours to form a surface layer.

After cooling, the sintered bodies were cut to identify the thickness and constituent components of the surface layer.
ZrB2 was identified at a film thickness of m.

Also, the above cut surface was examined under a microscope. As I guessed.

In all molded bodies, a diffusion layer was observed at the boundary between ZrO2 of the base material and ZrB2 of the surface layer.

FIG. 1 is a micrograph of the above-mentioned cut surface when a green molded body was used, and the results were almost the same when a calcined body or a sintered body was used.

Example 2 Carbon black was applied in the form of a slurry onto the surfaces of the same three types of molded bodies as in Example 1, and then heated in the same manner as in Example 1.

When the surfaces of the sintered bodies were observed, uniform surface layers were formed on all of them, and identification by X-ray diffraction revealed that a single phase ZrN surface layer was formed.

When the boundary between the base material and the surface layer was observed using a 1M translucent mirror, a diffusion layer was observed in both cases.

Example 3 Carbon black was applied in slurry form to the surface of the same 3!4 molded body as in Example 1, and then the culm was heated at 2.5°C/min to 1800°C with a N2 pressure of 10Toor for 2 hours. When held, all of the molded products had a gold-colored uniform surface layer in an F& shape. When this surface layer was identified by X-ray diffraction, it was found that a single phase of ZrN was produced.

When the boundary between the base material and the surface layer was observed under a microscope, a diffusion layer was observed in both cases.

Examples 4 to 7 Using the same sintered body as in Example 1 as the molded body, coating ff1
Example 4: B powder with an average particle size of 5 μm Example 5: BN with an average particle size of 5 μm Example 6: 50% by weight of the above B powder and 50% by weight of the carbon black used in Example 2 Mixture Example 7: A 712 compound of 50% by weight of the above BN powder and 50% by weight of the above carbon black was used, and the other conditions were the same as in Example 1.

When the generated surface layer was identified by X-ray diffraction, it was found that Example 4
: ZrB2 Example 5 : ZrB2 Example 6 : ZrB2. ZrN Example 7: ZrB2. When the cut surfaces were observed under a microscope, a diffusion layer was observed at the boundary between the base material and the surface layer in all molded bodies.

Examples 8 to 13 A sintered body of T i 02 (width 20 mm, thickness 30 mm, length 40 mm) was used as a molded body, and as a coating agent Example 8: B4G powder with an average particle size of 10 μm.Example 9: Average B powder Example 1O with a particle size of 10 μm: BN-undressed Example 11 with an average particle size of 10 μm:
Carbon black used in Example 2 Example 12: Mixture of 50% by weight of the above B powder and 50% by weight of the above carbon black Example 13: Using a mixture of 50% by weight of the above BN powder and 50% by weight of the above carbon black , and other conditions were treated in the same manner as in Example 1.

When the generated surface layer was identified by X-ray diffraction, it was found that Example 8
・TiB2 Example 9: TiB2 Example 10: 'i B 2 Example 11: TiN Example 12: TiB2.TiN Example 13: TiB2.TiN When the cut surface was observed with a microscope, it was found that Also in the molded product, a diffusion layer was observed at the boundary between the base material and the surface layer, and the first surface layer was firmly attached to the base material.

[Effects of the Invention] According to the present invention, the surface of a molded product containing zirconium oxide and/or titanium oxide has electrical conductivity, excellent friction resistance, and does not peel off from the base material. , a single phase or a mixed phase of zirconium boride, zirconium nitride, or zirconium carbide, or a single phase or a mixed phase of titanium boride, titanium nitride, or titanium carbide, thereby forming an electrode and can be easily metalized, and it is also possible to obtain effects such as extending the life of oxygen sensors and the like.

[Brief explanation of drawings]

FIG. 1 is a micrograph showing the bonding state between the base material (Zr02) and the surface layer (ZrB2) in Example 1 of the present invention.

Claims (1)

[Scope of Claims] 1. One or two types selected from the group consisting of boron carbide powder, boron powder, boron nitride powder, and carbon-containing substance powder on the surface of a molded body containing zirconium oxide and/or titanium oxide. zirconium oxide and/or zirconium oxide and/or
Or a method for surface treatment of a titanium oxide-containing molded product.