JPS6246959A - Heat-stability-resistant high toughness ceramic sintered body and manufacture - 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 [Field of Industrial Application] The present invention relates to a high-toughness ceramic sintered body, and more specifically, zirconia containing Y2O and CeO2 or CeO as a stabilizer, A1, Si, B, Periodic rate table 4a
, 5a, 6a, borides, carbides, nitrides of group elements, A
1□○1, MgO” A 120, (spinel), 3
A +20 s ・2 S io 2 (mullite),
The present invention relates to a high-toughness ceramic sintered body having excellent CrtO3 drying properties and thermal stability, and extremely little deterioration of strength and toughness over time, and a method for producing the same.

[Conventional technology 1 Zirconia sintered bodies undergo a phase transition from cubic to tetragonal to monoclinic in the high temperature range, but this is accompanied by a volume change, especially the volume of the phase transition from tetragonal to monoclinic. There is a drawback that the change is large and the sintered body is destroyed due to this volume change. To remove this drawback (in order to
A number of partially stabilized zirconias made of cubic crystals or partially stabilized zirconias made of cubic and monoclinic crystals have been published by dissolving ab, MgO, Y2O, etc. in order to prevent transitions. Furthermore, it has been announced that partially stabilized zirconia, in which a metastable phase of tetragonal crystals exists in a sintered body at room temperature, exhibits high strength. This is because when an external mechanical stress is applied to -, a phase transition from a metastable tetragonal crystal to a monoclinic crystal which is a stable phase at room temperature is induced, and the stress is absorbed. As described above, Y2O3 has been mainly used as a stabilizer to obtain a sintered body mainly consisting of tetragonal crystals which is metastable at room temperature, and has long been expected to exhibit high toughness and high strength. ing. However, this partially stabilized zirconia, which is mainly composed of tetragonal crystals, is metastable as a result of bringing the high temperature phase to a low temperature range, so its structure and properties change over time, especially at relatively low temperatures of 200°C to 400°C. Heating at low temperatures causes a phase transition to monoclinic crystal, and the strength deteriorates significantly over time. Further, this strength deterioration is severely accelerated in the presence of moisture, and such deterioration of properties over time is a ffJf problem.

For high-toughness ceramics that utilize the tetragonal to monoclinic phase transformation of zirconia, a different method is to embed microcracks in an alumina matrix and sinter the stress that occurs when a load is applied. A method for manufacturing a ceramic molded body with high fracture toughness that absorbs microcracks present in the body is disclosed. (Unexamined Japanese Patent Publication No. 52-8) In addition, unlike micro-cracks built in, up to 50% by volume of norfuniwaum oxide (zirconia), which does not contain a stabilizer, is built into a sintered body mainly made of a dense non-metallic cemented carbide. A sintered compact with improved strength has been disclosed (Japanese Unexamined Patent Publication No. 54-61215).However, since the zirconia contained in these two examples does not contain any stabilizer, the toughness and bending strength are low. Although the sintered body was significantly improved in terms of thermal stability, it was thermally unstable and the sintered body deteriorated significantly over time.

On the other hand, alumina, mullite, spinel, Si=
Ni, monoclinic or tetragonal zirconia containing no stabilizer is used as a ceramic embedding material in a ceramic matrix such as partially stabilized zirconia.
Ceramic sintered bodies containing up to 5 to 30 volume % of mainly tetragonal zirconia stabilized with 2 mol % of Y2O3 as an embedding material have been disclosed (Japanese Patent Laid-Open No. 59-64567). ). However, since the former does not contain a stabilizer in Zirphere, its strength deteriorates over time, and the latter is made by partially stabilizing zirconia with ittria, so it is extremely unstable thermally and easily deteriorates over time. It has the disadvantage of causing

In addition, as a high toughness zirconia sintered body, Y2O1, Mg
A1□O to zirconia containing O,6aO as a stabilizer
Sintered body containing up to 065 to 60% by weight of
32066) and a sintered body containing A12O3 or various phorides, carbides, nitrides, and Al2O in zirconia containing Y2O1 and MgO16aO as stabilizers (Japanese Patent Application Laid-Open No. 120571/1983).

However, among these disclosed zirconia sintered bodies, M
Those using FiOl6aO as a stabilizer have lower mechanical strength than those using Y2O as a stabilizer, and
Holding the temperature around ℃ for a long time causes breakathaxis, that is, transformation from tetragonal to monoclinic, resulting in +1! Due to the decrease in mechanical strength, its use as a VI structural material is limited. As mentioned above, the free-flowing sintered body has a temperature of 20
0 "Phase transition occurs easily at low temperatures of 0 to 400°C, and over time, the transition progresses from the surface of the sintered body toward the inside, resulting in severe deterioration of strength and toughness, and the toughening mechanism no longer works. In addition, it has a serious defect in that microcracks occur due to the volume expansion associated with phase transition, and it eventually breaks, making it unreliable as a structural material.

[Problem to be solved by the invention 1: Y20 containing Y2O as a stabilizer as described above]
High-toughness zirconia sintered bodies containing partially stabilized zirconia mainly composed of ZrO2-based tetragonal crystals are extremely unstable thermally, easily undergo phase transition at low temperatures of 200°C to 400°C, and deteriorate over time. Partially stabilized zirconia has the disadvantage of causing deterioration, and furthermore, it has the disadvantage of poor wear resistance.The present invention was made to solve these problems of high toughness zirconia. , which dramatically increases the thermal stability of the tetragonal crystal and reduces thermal aging deterioration.
．． :121hl+')':J'f:KAM:Depen! :
The purpose of this project is to improve the performance of high-toughness norconia sintered bodies as structural materials and expand their applications.

Means for Solving Problem E] The high toughness ceramic sintered body having excellent heat resistance stability according to the first aspect of the present invention has an I20. and CeO2 and/or Ce
A1, Si, and B in partially stabilized zirconia mainly composed of tetragonal crystals containing O2 as a stabilizer.

Borides and carbides of elements in groups 4a, 5a, and 6μ of the periodic table,
Nitride 4&I, AI□O,, M go-A I203(X
3AIzO*・2SiOz (mullite)
A sintered body containing 1 to 70% by internal weight of one or more selected from , Cr 203 as a dispersion component, and the average particle size of tetragonal zirconia crystal particles contained in the sintered body is 2μ or less. The gist is that

Partially stabilized zirconia ZrO3 and Y contained in the high toughness ceramic sintered body having excellent heat resistance stability of the first invention
The composition ranges of OIaS and CeO3 are plotted along three axes intersecting an equilateral triangle as shown in the attached drawing.
2, 2, In the triangular coordinates displaying the mol% of CeO2, point A (ZrOz87.5mol%, YOI, 512a+
o1%, CeOzO. 5 mol%) Point B (ZrOz95, 5 mol%, Y O2, s 4
mol%, CeO20.5 mol%) Point C (Z ro 295 , 5 mol%, YOl, 5
2 mol%, CeO□2.5 theory 01%) Point D (ZrO292, Omol%, YO+, sO++o
1%, CeO28.0 mol%) Point E (Zr0.84.5 mol%, YO3, .0 mol%
%, CeO, 15, 5 theory O1%).

Furthermore, among the dispersed components contained in the high toughness ceramic sintered body having excellent heat resistance stability of the first invention, A
□11, Si, B, borides, carbides, and nitrides of elements in groups 4a, 5a, and 6μ of the periodic table in AIN% TiC, TiN.

TiCN5TiB3, Si, N1, SiC%B, C, W
C,, T aC, N bC, Cr= C3, Crz B
%Z rN 1Z rB 3, ZrC, HrN, Hf
B3, HfC, and BN can be used.

The method for manufacturing a high toughness ceramic sintered body having excellent heat resistance stability according to the second aspect of the present invention is based on I20. and CeO2 and/
or ZrO2 powder containing CeO, as a stabilizer, or I20. Powder and CeO2 powder and ZrO2 powder or CeO2 powder and ZrO2 powder and A1, Si, B
, borides, carbides, nitrides of elements in groups 4a, 5a, and 6μ of the periodic table, A 1.0 2, Mg0-A I203 (X
pinel), 3ALOs・2SiO2 (mullite), Cr
A molded body of mixed powder obtained by pulverizing and mixing one type or 2fi or more powder selected from ZrO2 powder in a range of 1 to 70 internal weight % with respect to ZrO2 powder is fired, The gist of the present invention is to produce a sintered body in which the average particle diameter of the tetragonal norphea crystal particles contained therein is 2 μω or less.

Y2O3 used in this manufacturing method of the tJIJ2 invention
, CeO□, and ZrO2 powder, as shown in the attached drawing, Z r O3
,YO In the triangular coordinates displaying the mol% of OI+S and CeO2, point A (ZrOz87.5mol%, YO, , 12mol
1%, CeO20.5 mol%) Point B (ZrO295.5 mol%, YO,, s4 mol
%, CeO20,5IIO1%) ' Point C (ZrO295,5T6o1%, YO1.52mo
l%, CeO22.5 Peng o1%) Point D (ZrO292, Omol%, Y O+ , s
Omol%, CeO28. 0mol%) Point E (Zr0284.5too1%, Y O3, sOl
llol%, CeO215.5mol%, YO1.50
The composition can be within a range surrounded by a line connecting five specific composition points shown in mol%, CeO2 (15.5 mol%).

In addition, among the dispersed components used in the manufacturing method of the second invention, A1, Si, B, borides, carbides, and nitrides of elements in groups 48.5a and 6μ of the periodic table are substituted with AlN, TiC, Ti.
N5TiCN, TiB3, Si*NiSiC, B, C
, WC, TaC, NbC1CrmC3, Cr2B,
Z rN , Z rB 3, ZrC, HfN, HfB
z, Hf0% BN.

Furthermore, Y2O used in the manufacturing method of this second invention,
ZrO, powder containing CeO2 and/or CeO2 as a stabilizer is prepared by uniformly mixing a sol and/or water-soluble salt of ZrO□ with Y203 and a water-soluble salt of CeO□ in a solution state. , the Z r O2 powder obtained can be separated in the form of a precipitate.

Note that through the first invention and the second invention, part or all of Z r O2 can be replaced with Hf O2.

[Effect 1] The high toughness ceramic sintered body of the present invention is different from conventional Y, o, -
Ce is added to the ZrO□-based partially stabilized Zirphere sintered body composition.
Oz component, A1, Si, B, periodic table 4a.

Borides, carbides, nitrides, Al2 of group 5a and 6a elements
01, MgO・A 1.0, (spinel), 3A+2
03.2 By newly adding one or more selected from SiOa (mullite) and Cr2O3 as a dispersion component, high strength and high toughness are achieved, and the temperature range is conventionally considered to be thermally unstable. There was almost no change after a long-term thermal deterioration test, showing extremely high strength and excellent thermal stability.

This is because the crystal structure of tetragonal zirconia stabilized by the addition of Ce 02 in fjrJl is different from that of conventional Y2O,
This is because the crystal structure of zirconia is closer to the cubic crystal structure, which is a high temperature stable phase of zirconia, than that of tetragonal zirconia stabilized by zirconia. Addition of a dispersion component such as Al2O to @2 increases the content of tetragonal crystals, which contributes to an increase in fracture energy due to an increase in elastic modulus, exhibiting high strength, and the presence of a dispersion component increases the Z r O2 grains. It helps strengthen the iL part and also increases the stability of metastable tetragonal zirconia.
Furthermore, it is thought that the heat resistance stability is significantly improved as a result of the synergistic effect with stability due to the presence of the CeO2 component.

In addition, the hardness is also improved due to the presence of the dispersion component, and ZrO2
It further improves the wear resistance of the zirconia sintered body, and improves the mechanical properties such as hardness, strength, and creep of the zirconia sintered body at high temperatures. Y203-CeO2, which is contained in the sintered body of the present invention and is more thermally stable and does not show deterioration.
Since the Z r O2-based tetragonal norphea is a metastable tetragonal crystal, when stress is concentrated near the Z r O2 particles, it transforms into a monoclinic crystal which is a low-temperature stable phase.
It has the effect of relieving stress. Therefore, the high toughness ceramic sintered body of the present invention exhibits high strength and high toughness.

The present invention requires Y 20 y and Ce 02 as stabilizers for zirconia. Y2O,, Ce O3, Z
The blending amounts of the three components of rO2 are preferably selected within the range surrounded by lines connecting points A, B, C, D, and E in triangular coordinates as shown in the drawing. If it is within this range, the stability of the tetragonal crystal is high (excellent in heat resistance), but if it is outside this range, the heat resistance will be significantly reduced and the mechanical properties will also be poor.

That is, 1. Y than αA(YO,,s12mol%)
If a large amount of O+ and s are included, the toughness decreases, and J:B
Y O2, than (Y O+ , s 4 mol%)
.

When the amount is small, heat resistance stability is lost. Point C(Y
If YOl and CeO2 are less than O1,s2 mol%tce022.5 mol%), the heat stability will be poor. In addition, if CeO2 is less than point D (CeO28 mol%), the heat resistance stability will be poor, and point E (CeO28 mol%) will be inferior.
O215.

Smol%) Upper Q t, CF! If there is too much O, sufficient mechanical strength cannot be obtained.

In order to make the present invention more effective, the amounts of the three components mentioned above should be expressed in triangular coordinates as shown in the drawings.
・ Point A (ZrOz87.5mol%-Y O1,s 12
+*o1%, CeO20.5a+o1%),'#,H(ZrO294,5mol%tYO1,s4
mol%, CeO□1.5cao1%) Point G (ZrOz94.5+o1%, YO+, s2.5m
ol%.

CeOz3IIlo1%) Point F (Zr0.81mol%, Y O2,, Omol%
, Ce O29mol%) Point E (ZrO284,5io1%, YO1., Omol
%, CeOz15.5 mol%).

Note that a part of Y2O, is replaced with Nd2O, Yb20. , La
It is also possible to substitute with rare earth metal oxides such as 2O5, Er, 03, etc.

In the present invention, A1, Si%B, Periodic Table 4a, 5a.

Borides, carbides, nitrides of group 6a elements, A1□01,
MgO・A I203 (spinel), 3A+□03・2
1 selected from SiO2 (mullite), Cr2O,! g
1 to 70% by internal weight of i or 2 or more as a dispersion component
Must be included. The reason for limiting the amount of dispersion component added is
This is because if it is less than 1% by internal weight, the effect of addition is small, and if it is more than 70% by internal weight, the content of ZrO□, which has toughness, is reduced.

In order to make the present invention more effective, it is preferable to select the amount of the dispersion component added in the range of 5 to 50% by internal weight.

These dispersion components include A I20 2, MgO・A
l2O, (spinel), 3Al□0.・2SiOz (mullite), Cr2O3, AlN, TiC
% TiN % T1CN 1TiB2.5izN<,
SiC, B4C, WC, TaC.

N bC, Cr3 C3, Cr2B, ZrN, ZrB3
, ZrC.

HfN, HfB3, HfC, BNl and mutual solid solutions thereof are mentioned and preferred. Especially A1□01
, AlN, TiC1TiN%TiCN5TiBz, si
3N4, sic, B, C, WCXTaC, NbC are good.

The manufacturing method according to the second aspect of the present invention is usually carried out as follows. Zr containing Y2O3 and Cen2 as stabilizers
O2 powder or Y2O, and CeO2 and ZrO2
Powder, A1, Si, B, borides, carbides, nitrides of elements of groups 4a, 5a, and 6B of the periodic table, A1□0, M[l
O・A I203 (X l:' * le), 3A120
i"2Si○2 (Murai)), Cr2O, or two or more powders added as dispersion components are pulverized and mixed, and then molding aids such as polyvinyl alcohol are added as necessary. If the dispersed component is an oxide, it is heated in air, vacuum, or oxygen atmosphere.
In a hydrogen atmosphere, a carbon atmosphere, an inert gas atmosphere such as N3 or argon gas, or in a vacuum if the dispersed component contains a non-oxide, an inert gas atmosphere such as N3 or argon gas, or carbon Sintering is performed at 1350-1650°C for 0.5-5 hours in a non-oxidizing atmosphere such as normal pressure under pressure.

In particular, when the amount of non-oxide dispersed components is large, it is preferable to apply a hot press method (HP method) or a hot isostatic press method (HIP method).

In the case of the HP method, the compact is loaded into a graphite mold in a non-oxidizing atmosphere and fired at 1350-1650°C under a pressure of 50-300 Kg/cm2. In the case of the HIP method, a non-porous sintered body with a phase N density of 95% or more is obtained in advance by normal pressure sintering, hot pressure sintering, hot pressing, etc., and then 100 OKH/ 0 at a gas pressure of car2 or higher and a temperature of 1100°C or higher and 1800°C or lower.
It is preferable to carry out sintering for 5 hours or more.

The partially stabilized norconia of the present invention is a raw material obtained by uniformly mixing a ZrO2 sol and/or a water-soluble salt in a solution state with a stabilized water-soluble salt and then separating it in the form of a precipitate. As a result, the stabilizer is uniformly dispersed in ZrO2, and an easily sinterable powder consisting of extremely fine particles can be used as a raw material.As a result, it has a fine and uniform composition and has almost no micropores. A sintered body is obtained, and desired values of strength and toughness are also obtained.

In the present invention, raw materials used as dispersion components
+11+Q l'l'M +? Ding 1-m
t, e> he h-t happy Ac
QO-98% can also be used effectively. In the case of extremely fine particles, it is more appropriate to express the particle size by the specific surface area than by the average particle diameter.
It is preferable to use a material with a thickness of n+2/F1 or more and a density of 10 m2/g or more.

The high toughness ceramic sintered body of the present invention preferably has a relative density of 95% or more, more preferably 98% or more, in order to improve heat resistance stability. Furthermore, the higher the relative density, the higher the stability of the tetragonal norphea contained in the sintered body, resulting in excellent heat resistance stability, strength, and toughness.

Since the norconia sintered body having the composition of the present invention is partially stabilized zirconia mainly composed of tetragonal crystals, it exhibits high strength and high toughness. Tetragonal crystal is originally a metastable phase, so when the sample surface is ground, a portion of the sample undergoes a transition to monoclinic crystal, and the residual compressive stress in the surface layer contributes to the strengthening of the sintered body. The degree of this strengthening depends on the surface roughness caused by grinding and the grain size of the sintered body. Therefore, the partially stabilized norconia mainly composed of tetragonal crystals according to the present invention refers to zirconia containing at least 20% or more of tetragonal crystals in a mirror state as measured by x#1 diffraction. If the tetragonal system content is 20% or less, the toughness will decrease, so it is necessary that the tetragonal system content be 20% or more.

In the sintered body of the present invention, it is necessary that the average crystal grain size of the tetragonal zylphere contained in the sintered body is 2 μm or less. Preferably it is 1 μμ or less. More preferably, the thickness is 0.5 μm or less.

When the average crystal grain size exceeds 2 μm, it becomes monoclinic and its toughness decreases. *In addition, the smaller the average crystal grain size of the tetragonal zirconia, the better the stability and the better the heat resistance.

In the present invention, the average crystal particle size of Norphea is Cu
It was determined by the X-ray diffraction method using Ka rays, using the formula D=0,89λ(B−b)cosθ. Here, D is the desired crystal grain size of zirconia, which is the wavelength of the CuKQ line, which is 1.541A, and B is the width (in radians) of the diffraction line of the monoclinic (111) or tetragonal (111) plane of zirconia. The larger value of these,
b is the half-life width (in radians) of the (101) plane of the crystal grain [3000X or more a quartz] added as an internal standard, and θ is the diffraction angle 2 of the diffraction line used to measure the half-life width of Norphea.
The value of θ is 172.

Zr0= of the zirconia sintered body of the present invention exhibits exactly the same characteristics even if part or all of it is replaced with HFO2.

[Example 1] The present invention will be described in detail below to clarify the effects of the present invention.

(Example 1) The purity of the obtained powder was 99.
Yttrium chloride with a purity of 99.9% and cerium chloride with a purity of 99.9% are added to the Norfnia sol solution obtained by hydrolysis of a 9% aqueous solution of zirconium oxychloride, and the uniformly mixed solution is coagulated with an alkali and water is added. The oxide was precipitated, dehydrated and dried, and calcined at 900°C to obtain partially stabilized zirconia powder. This powder is 25a+
``It shows a specific surface area of 7g.

This powder contains Al with an average particle size of 0.38 m1 and a purity of 99.9%.
2O and fine particles of TiN with an average particle size of 0.1 μm and a purity of 99.9% were added in the proportions shown in the PJS1 table, and the wet mixed & dried powder was isotropically molded at a pressure of 1.5 ton/am2. , 2 at a temperature of 1400-1650°C in nitrogen
Baked for an hour. The average crystal grain size of the tetragonal zirconia contained in the obtained sintered body was all 2 μm or less.

The obtained sintered body was cut and polished to a size of 3 x 4 x 40 tnm, and the bulk density, crystal phase, flexural strength, and fracture toughness, as well as the crystal phase and flexural strength of the sintered body surface after a thermal deterioration test, were evaluated. The results are shown in Table 1.

In addition, as a method for measuring each physical property, the bending strength was measured according to the JIS standard using a 3x4x40mm sample piece, with a span of 301 mm.
1 The average value of 10 pieces was shown by three-point bending at a crosshead speed of 0.5 + nm/min.

Fracture toughness was measured by making an indentation under a load of 50 kg by the microindentation method, and the KIC value was determined using Shinryo et al.'s formula.

Ta. That is, the integrated intensity IM of the monoclinic (111) plane and the (111) plane of the sample mirror-polished with diamond paste, and the integrated intensity IT and IC of the tetragonal (111) plane and the cubic (111) plane. Therefore, the amount of monoclinic crystal is M (amount of monoclinic crystal) = X100...(1)
The primary sintered body determined by the formula IT+Ic+IN was pulverized to 5μ+a or less, and the integrated intensities IM and IC of monoclinic ZrO□ and cubic ZrO2 were determined by X#X diffraction under the same conditions.

During this pulverization process, the tetragonal crystal Z that existed in the sintered body
r O2 is fi + mental stress all monoclinic ZrO2
It is thought that it will metamorphose into Therefore, the amount of cubic crystals is determined by, and from this, the amount of tetragonal crystals is (f amount of crystals) = 100 - + (amount of monoclinic crystals) + (amount of cubic crystals)
) was determined.

In the thermal deterioration test, the sample was held in an electric furnace at 300° C. for 3000 hours, and then the sample was taken out and its physical properties were measured.

The amount of monoclinic crystals after the thermal deterioration test was determined by X-ray diffraction of the sample surface in the same manner from the above formula (1).

In this example, A I20 and TiN were used as additive components.
constant ff1 (in this example, 20% by weight and 10% by weight)
) was added, and CeO2 was added at various m01% while Y2O2,... was gradually increased stepwise from 0 to 10 uo1%.

In Table 1, Sample No. 1-5 does not contain any Y2O2, and the number of moles of CeO2 added is gradually increased. Comparative example No. 1 is ZrO□, Y O
, 5. It contains less 6aO than the composition point of triangular coordinates indicating m01% of CeO2, but the amount of single yarns after the thermal deterioration test is large and the bending strength is extremely low. Conversely, N containing more CeO2 than the composition point E on the triangular coordinates
o, 5, only low values can be obtained for both fracture propensity and bending strength. On the other hand, inventive examples Nos. 2 to 4, which have compositions between point E and point E, showed high values for all of the relative density, fracture toughness, and bending strength, and even after the thermal deterioration test, they showed a transition to monoclinic crystal. The fact that there is no visible deterioration in bending strength and that there is almost no deterioration in bending strength is fI! I made it clear.

Sample No. 6-9 has YO2, 2,5 m01
% and the example N006 is ZrO3, YOl, 9, C
Although it has a composition that deviates from the range surrounded by the 5ML points of ABCDE, the triangular coordinate system that displays m01% of eO2, on the side with less CeO2, it shows high values for both bending strength and fracture toughness. There are many monoclinic crystals after the thermal deterioration test, and the strength deteriorates significantly. Sample No. 9 is ZrO3, Y
Ol+5, 5 composition of ABCDE of triangular coordinates displaying 01% of CeO2, CeO2 than the range surrounded by α
This is a comparative example that is on the high side, and although the relative density is high, the fracture toughness and bending strength are not sufficiently improved. On the other hand, invention examples No. 7 to 8, which are within the range surrounded by the 5 composition points of ABODE in the triangular coordinates, have high values for both fracture toughness and bending strength, and even in the thermal deterioration test, they become monoclinic. It was confirmed that no migration occurred and no deterioration in strength was observed.

Samples No. 10 to 14 have a composition of 4 mol of Y O1,s.
%, and the addition of Cen2 is changed by -01%. Comparative example No. 10 did not add CeO2 at all, and although it showed a high value in the area surrounded by the five composition points of ABCDH in the above triangular coordinates, there were many monoclinic crystals after the thermal deterioration test, and the strength deteriorated. stomach. Also, let CeO□ be A of the above triangular coordinates.
5 of BCDE. In Comparative Example No. 14, in which the amount was added in an amount larger than the range surrounded by the 1L point, although the relative density was high, the fracture toughness and bending strength could not be sufficiently changed. On the other hand, C
Inventive examples Nos. 11 to 13, in which the amount of eO2 added is within the range surrounded by the five composition points of ABCDH in the above triangular coordinates, obtained high values for both fracture toughness and bending strength, and even in the thermal deterioration test, they were found to be monoclinic. It became clear that no dedication occurred and the strength did not deteriorate.

Similarly, sample No. 15-18 has a composition of 6 mol% of YO1,s, and sample No. 19-22 has a composition of YO18.
, with the composition of 8aAo1%, and 0~12㎜1% CeO2 added, respectively. Sample No., 23
The composition of Y O2, , is 10 mol %, and CeO, is 2 m.

1% was added. Comparative examples No. 15 and No. 19, in which no CeO□ was added, had a high phase N density, but after the thermal deterioration test, there was a lot of transition to monoclinic crystal, and the bending strength deteriorated severely. CeO2, Z r O3,
Comparative examples No. 18 and No. 0022 were added in an amount larger than the range surrounded by the 5IIL point of ABCDE, the triangular coordinate system showing the mol% of YO, , 6, CeO2,
Although the relative density is high, the fracture toughness and bending strength cannot be changed sufficiently. In comparison, ABCDE of triangular coordinates showing the mol% of ZrO, YO1,s, CeO2, which is the composition range of the present invention. Sample No. 16-17 with excess Y O3,s and CeO2 within the range surrounded by the five composition points of
, No., 2O321', No. 23, all obtained high values for both fracture toughness and bending strength, and it was confirmed that no transition to monoclinic crystal occurred and no deterioration in strength was observed in the thermal deterioration test. It was done. It was confirmed that the same results as in this example could be obtained with other dispersion components and amounts added according to the present invention.

(Example 2) For monoclinic zirconia with a specific surface area of 25 m2/g and a purity of 99% or more, Y2O1 and Ce were added as stabilizers.
O2 was added in the proportions shown in Table 2, and A1□O1 with an average particle size of 0.3 μm and a purity of 99.9% was added as a dispersion component.
Mg0-A I with average particle size of 0.3μ and purity of 99.9%
203 (spinel), specific surface area 28II12/B, A
Synthetic mullite (3A120s・2S+02) with I203/S io f ratio of 71.8/28.2, average particle size 065 μm, 99% purity Cr 20 s and purity 98
% or more, AIN% TiC with a specific surface area of 10 to 27 g or more,
TiN.

T iCN %T i B z, 5isN-1SiC%
B, C%WC1T a C, N b CSCr y C
3, Cr2 B SZ rN 1Z rB 3, ZrC
, HfB3, and BN in the proportions shown in Table 12, wet-mixed and dried powder was filled into a carbon mold, and the mixture was heated to 200 kg/cm.
2. Baking was performed for about 1 hour using a hot press method at a temperature of 1400 to 1500°C.

The average crystal grain size of the tetragonal zirconia contained in the obtained sintered body was all 2 μm or less. The bulk density, crystal phase, flexural strength, and fracture toughness of the obtained sintered body were measured in the same manner as in Example 1, and the crystal phase and flexural strength of the surface of the crystal body after the thermal deterioration test were measured. It is shown in Table 12.

In this example, 3001 YO2 was used as a stabilizer.
%, CeO2 was added at 6+ao1%, and various dispersion components were added at 30% by weight.

Sample No. 24-26.28-31.33-34, HaA
+20), M8o-A I203 (Shi*ru), 3AI□O1・2Si○2 (mullite), AlN,
TiC, TiN.

T1CN, Si3N4, and 5iC1 were added individually in an amount of 30% by weight. Also, sample No. 27.32.36
-43.45 is Al20325% by weight and Cr2O7
, T i B 3, B 4C, W C, T a C, N
b C, Cr) C3, Cr2B, ZrN, ZrB3,
ZrC and BN are added in an amount of 5% by weight,
Samples N0844 and 46 contained 25% by weight of 5i3N4,
5% by weight of Hf B 2 or TiN was added. As is clear from Table 2, the phase N density, fracture toughness, and bending strength are high for both the single dispersion component and the two dispersion components, and even in the thermal deterioration test, the transition to monoclinic crystal was observed. There is no visible change in bending strength, and there is almost no deterioration in bending strength. In addition, sample No. 47 is a stabilizer /VA
/F-11,? -1-p6-1-114410511-
Even with the addition of 30% by weight of a dispersion component of n k 7-J+ (Al[F), thermal deterioration is severe, and after the thermal deterioration test, the amount of monoclinic crystals increases and the bending strength deteriorates severely.

(Example 3) The purity of the obtained powder was 99.
Norconiacyl solution obtained by hydrolysis of a 9% aqueous solution of zirconium oxychloride contains 4i degree 99.9%
Yttrium chloride of 99.9% purity and cerium chloride of 99.9% purity are added, and the uniformly mixed solution is coagulated with alkali to form a hydroxide precipitate, which is dehydrated and dried and calcined at 900'C to partially stabilize it. Zirconia powder was obtained. This powder is 2
5II12/Bi specific surface area is shown.

To this powder, A with an average particle size of 0.3 μm and a purity of 99.9% was added.
1□03 and specific surface area of 10 m2/g or more, purity of 98% or more T i CN SS i C, S i 3 N 1
, AIN were added as dispersion components in the proportions shown in Table 3, and the powder was wet-mixed and dried at 1.5 ton/c++.
Molded isotropically at +2 pressure, 1350~1500″C
Pre-sinter for 2 hours at a temperature of 2 hours or 200 Kg
/can21 Hot-pressed at 350 to 1500°C for 1 hour to obtain a non-porous sintered body having a theoretical density of 95% or more. This sintered body was
Firing was carried out in a hot isostatic press at 1450-1600° C. under 1112° C. pressure for 1 hour. The average particle diameter of the tetragonal zirconia contained in the obtained sintered body was 2 μm or less in total.

The obtained sintered body was measured in the same manner as in Example 1 for bulk density, crystal phase, flexural strength, fracture toughness, and crystal phase and flexural strength on the surface of the sintered body after the thermal deterioration test. Pt the result
It is shown in Table 53.

In Table 3, samples Nos. 48 to 52 have 1% of YOl, s4+ao and 1% of CeO24L6o added as stabilizers, and 5 to 70% by weight of 0 A1□ as a dispersion component. In addition, samples Nos. 53 to 54 contained 4a+o1% YO, ,5 and CeO as stabilizers.

to which Si, N4. At2
Samples No. 01 and AIN were added in a total of 50 to 70% by weight, and samples Nos. 55 to 56 had the same stabilization tolerance and added 25 to 40% by weight of S isN as a dispersion component. be. Samples Nos. 57 to 59 also had the same stabilizing tolerance, and the dispersion component was a combination of Al2O, SiC, and T1CN added in an amount of 25 to 40% by weight. All samples showed high values in relative density, fracture toughness, and flexural strength, and furthermore, even after the thermal deterioration test, no transition to monoclinic crystal was measured, and the flexural strength hardly deteriorated, demonstrating the effect of the present invention. confirmed. In addition, sample No. 60 contains 4 mol% of YOl, s, and C as stabilizers, respectively.
This is a comparative example in which eO2 is added and Al2O in a composition range above the composition range of the present invention is added as a dispersion component, but although the relative density is high, the fracture toughness and bending strength cannot be sufficiently changed.

In samples No. 61 to 67, YOl+5 was used as a stabilizer.
The amount of the dispersion component added was varied between when CeO2 was not added and when CeO2 was added while keeping it constant at 6.01%. Sample No. with no addition of Ce O2.

In Nos. 61 to 63, even if a dispersion component was added, the thermal deterioration was severe, and after the thermal deterioration test, the materials transformed to monoclinic crystals, resulting in a significant deterioration in bending strength. Sample No. 64 is a comparative example in which 1.5 mol % of CeO2 is added as a stabilizer and no dispersion component is added, but thermal deterioration similarly occurs.

On the other hand, samples Nos. 65 to 67 contain Y2O and CeO2 as stabilizers and as dispersion components.
In the present invention examples in which iAl 203 was added in an amount of 10 to 4 Ofi, high values were obtained for both fracture toughness and bending strength, and even in thermal deterioration tests, no transition to monoclinic crystal occurred and the strength did not deteriorate. It was confirmed that it was not visible.

Moreover, among the samples of this example, No. 49 to 50.55
~57.59.61, the hardness was measured using a Rockwell Superficial hardness tester under a load of 45 kg, and the results are shown in Table 4.

From the fjS4 table, 4 mol% Y O2 as a stabilizer
,.

Sample Nos. 49 to 50.5, which are examples of the present invention, added CeO2 and A1□O as a dispersion component.
5-57 and 59 are 6m as a stabilizer.

It can be seen that the hardness is significantly improved compared to the partially stabilized zirconia sintered body of sample No. 61, which is a comparative example in which only 1% of Y 2 O 2 is added and no dispersion component is added.

(Example 4) Among the sintered bodies prepared by the method of Example 3, sample No. 24.50.66 was used as an example of the present invention, and sample No. 61, 62.64 was used as a comparative example. used, 300
It was kept in an electric furnace at °C for a specified period of time and subjected to a thermal deterioration test.
The amount of monoclinic crystals on the surface of the sintered body was measured, and the relationship between the holding time and the amount of monoclinic crystals is shown in Figure @2.

In FIG. 2, sample No. 24.50, which is an example of the present invention,
．． Although No. 66 was held for 1500 hours, almost no transition to monoclinic crystal occurred. On the other hand, Y2O3
Comparative example No. 61, Y which is ZrO□ system and does not contain dispersion components
Comparative Example No. 63, which is a 2O, -ZrO2-ALOi system and does not contain CeO2, and Comparative Example No. 64, which is a Y2O3CeO2ZrO2 system and does not contain any dispersion components, is heated at 300°C.
It can be seen that a transition to monoclinic crystal occurs during storage in air, resulting in thermal deterioration.

From this, it was confirmed that the high toughness ceramic sintered body having the composition of the present invention exhibits extremely superior thermal stability compared to each of the sintered bodies of comparative examples. The high-toughness ceramic/resintered body with excellent toughness is made of the conventional Y2O-ZrO2-based partially stabilized zilphnia sintered body, with CeO2 component, A1%511B, Z! ! ! Table 4a, 5a, 6a group elements borides, carbides, nitrides, Al2O3, MgO-A I203 (X l
:'Nel), 3 A +20 s' 2 S io
2 (mullite), one or two selected from CrzO5
By newly adding more than 100% of the seeds as a dispersion component and controlling the average particle size, it is a highly tough ceramic sintered body with improved strength, excellent thermal stability, and extremely little deterioration of strength and toughness over time. 0 When the high toughness ceramic sintered body of the present invention with excellent heat resistance stability is used as a sliding member, the wear resistance is about 10 times or more compared to the 3 mol Y2O3 partially stabilized norconia sintered body. can get. The present invention thus improves the hardness of the partially stabilized norconia sintered body and further improves the wear resistance. Furthermore, due to the addition of dispersion components, it has superior mechanical properties such as hardness, strength, and creep compared to conventional norconia sintered bodies at high temperatures.

The high toughness ceramic sintered body of the present invention with excellent heat resistance stability has excellent properties at room temperature and high temperature, so it can be used for wear-resistant ceramic screws and brass rods for injection molding machines for thermoplastic resins and ceramics. and hot extrusion dies such as steel pipe shells, internal combustion engine parts such as gas turbine parts and diesel engine parts, pump parts, industrial cutters, cutting tools, parts for crushing machines, sliding parts, artificial bones, artificial teeth, and cast ceramics. Bridge core materials for artificial teeth, artificial roots, daisies, etc. (these materials greatly contribute to the application and practical use of martial arts soldiers and to the improvement of performance.

FIG. 1 is a triangular coordinate showing the composition range of Z r O3, YO1.5, and CeO2, and FIG. 2 is a diagram showing the relationship between the time of the thermal deterioration test and the amount of monoclinic crystal in Example 4.

Claims (9)

[Claims] (1) Y_2O_3 and CeO_2 and/or CeO
Partially stabilized zirconia mainly composed of tetragonal crystals containing _2 as a stabilizer contains Al, Si, B, 4a of the periodic table,
Borides, carbides, nitrides of group 5a and 6a elements, Al_
2O_3, MgO・Al_2O_3 (spinel), 3A
l_2O_3・2SiO_2 (mullite), Cr_2O
A sintered body containing 1 to 70% by internal weight of one or more selected from _3 as a dispersion component, and the average particle size of the tetragonal zirconia crystal particles contained in the sintered body is 2 μm or less. A high-toughness ceramic sintered body with excellent heat resistance and stability. (2) Partially stabilized zirconia contains Y_2
As shown in the attached drawing, ZrO_2, YO_1_. ＿５、
In the triangular coordinates displaying the mol% of CeO_2, point A (ZrO_287.5 mol%, YO_1_._51
2 mol%, CeO_20.5 mol%) Point B (ZrO_295.5 mol%, YO_1_._5
4 mol%, CeO_20.5 mol%) Point C (ZrO_295.5 mol%, YO_1_._5
2 mol%, CeO_22.5 mol%) Point D (ZrO_292.0 mol%, YO_1_._5
0 mol%, CeO_28.0 mol%) Point E (ZrO_284.5 mol%, YO_1_._5
0 mol%, CeO_215.5 mol%) A high toughness ceramic sintered body with excellent heat resistance stability according to claim 1 having a composition within the range surrounded by a line connecting five specific composition points shown as . (3) Al, Si, B, borides, carbides, and nitrides of elements in groups 4a, 5a, and 6a of the periodic table are AlN, TiC, T
iN, TiCN, TiB_2Si_3N_4, SiC,
B_4C, WC, TaC, NbC, Cr_3C_2, C
r_2B, ZrN, ZrB_2, ZrC, HrN, Hf
The high toughness ceramic sintered body having excellent heat resistance stability according to claim 1, which is B_2, HfC, and BN. (4) The high-toughness ceramic sintered material having excellent heat resistance stability according to claim 1, wherein the zirconia monoclinic content contained in the sintered body after being held in the atmosphere at 300°C for 3000 hours is 30% or less. Concretion. (5) The high-toughness ceramic sintered body according to any one of claims 1 to 4, in which part or all of ZrO_2 is replaced with HfO_2. (6) Y_2O_3 and CeO_2 and/or CeO
ZrO_2 powder or Y_2 containing _2 as a stabilizer
O_3 powder and CeO_2 powder and ZrO_2 powder or CeO_2 powder and ZrO_2 powder, Al, Si,
B, borides, carbides, nitrides of elements of groups 4a, 5a, and 6a of the periodic table, Al_2O_3, MgO・Al_2O_3
(spinel), 3Al_2O_3, 2SiO_2 (mullite), and Cr_2O_3 as a dispersion component of one or more powders selected from ZrO_2 powder.
A molded body of mixed powder obtained by pulverizing and mixing in a range of ~70% by internal weight is fired to produce a sintered body in which the average particle size of the crystal grains of tetragonal zirconia contained is 2 μm or less. A method for manufacturing a high toughness ceramic sintered body. (7) The composition ratios of Y_2O_3, CeO_2, and ZrO_2 are determined by plotting ZrO_2, YO_1_. _5, m of CeO_2
In the triangular coordinates that display ol%, point A (ZrO_287.5mol%, YO_1_._5
12 mol%, CeO_20.5 mol%) Point B (ZrO_295.5 mol%, YO_1_._5
4 mol%, CeO_20.5 mol%) Point C (ZrO_295.5 mol%, YO_1_._5
2 mol%, CeO_22.5 mol%) Point D (ZrO_292.0 mol%, YO_1_._5
0 mol%, CeO_28.0 mol%) Point E (ZrO_284.5 mol%, YO_1_._5
7. The method for producing a high-toughness ceramic sintered body according to claim 6, wherein the composition is within a range surrounded by a line connecting five specific composition points shown as (0 mol%, CeO_215.5 mol%). (8) Al, Si, B, borides, carbides, and nitrides of elements of groups 4a, 5a, and 6a of the periodic table are AlN, TiC, T
iN, TiCN, TiB_2, Si_3N_4, SiC
, B_4C, WC, TaC, NbC, Cr_3C_2,
Cr_2B, ZrN, ZrB_2, ZrC, HfN, H
The method for producing a high toughness ceramic sintered body according to claim 6, which is fB_2, HfC, and BN. (9) Y_2O_3 and CeO_2 and/or CeO
ZrO_2 powder containing ZrO_2 as a stabilizer is
The sol and/or water-soluble salt of 2 is Y_2O_3, C
The method for producing a high toughness ceramic sintered body according to claim 6, wherein the ZrO_2 powder is obtained by uniformly mixing eO_2 in a solution state with a water-soluble salt and then separating it in the form of a precipitate.