AU601999B2 - High strength zirconia ceramic - Google Patents

Description

COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952-69 COMPLETE SPECIFICATION

(ORIGINAL)

Form Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority: Related Art: do'umcrifne contaiins ti L 49 udi i;t s il.'de ur;ct :r on 49 and is ;-cr ct t,,i

II

Name of Applica' t: Address of Applicant: N G K INSULATORS, LTD.

2-56, Suda-cho, Mizuho-ku, Nagoya-shi, Aichi-ken, Japan KYOSUKE TSUNEKAWA, KEN FUKUTA and MUNEYUKI IWABUCHI EDWD. WATERS SONS, 50 QUEEN STREET, MELBOURNE, AUSTRALIA, 3000.

21 Actual Inventor: Address for Service Complete Specification for the invention entitled: HIGH STRENGTH ZIRCONIA CERAMIC The following statement is a full description of this invention, including the best method of performing it known to us i- -0 I V, A The present invention relates to zirconia ceramics and is more particularly concerned with zirconia ceramic compositions superior in bending strength, acid resistance and thermal stability.

Zirconia ceramics containing 1.5 -5.0 mol% yttria as a stablizer are each known in the art as a i partially stabilized zirconia ceramic (PSZ) which has been developed as a high strength zirconia ceramic j useful for mechanical structure materials. The partially stabilized zirconia ceramic is, however, still insufficient in bending strength. In Japanese Patent Early Publication No. 60-226457, there has been proposed a method of producing a high strength zirconia ceramic the bending strength of which is higher than that of the partially stabilized zirconia ceramic. In this method, raw material fine powder with a specific primary mean particle diameter was mixed at a predetermined ratio and made by Hot Isostatic Pressing or sintered by uniaxial pressing to produce a ceramic composition consisting essentially of Zr0 containing 1.5 5.0 mol% Y 2 0 3 and 2 2 3 Al 203-MgO as a stabilizer.

During change of the ambient temperature from a high temperature to room temperature, the zirconia ceramic in the cubic structure form transforms into the 2 7 t- 'i_ tetragonal structure then to the monoclinic structure form with consequent volume changes. When the crystal structure changes on cooling from tetragonal to monoclinic, the zirconia ceramic is degradated due to a volume expansion thereof. For the purpose of preventing such degradation, there has been proposed a method of jI restraining the transformation of crystal stucture in ZrO 2 by solid solution of a stabilizer such as CaO, MgO, Y203 and the like. At present, Y 2 0 3 is used as the stabilizer to produce a partially stabilized zirconia ceramic of high strength and fracture toughness in the tetragonal structure form at room temperature. Such partially stabilized zirconia ceramics are, however, unstable in crystal phase and transform into the monoclinic structure when heated at a relatively low 0 0 temperature within a range of 200 400 C, resulting in Sdeterioration in strength, toughness and thermal stability thereof.

To enhance the strength and thermal stability, L 20 a zirconia ceramic composition consisting essentially of ZrO 2 containing Y 2 0 3 and Al20 3 has been proposed in Japanese Patent Early Publication No. 58-32066, and a zirconia ceramic composition consisting essentially of ZrO 2 containing Y 2 0 3 CeO 2 and A1 2 0 3 has been further proposed in Japanese Patent Early Publication No.

3 i i 61-77665. In the former publication, a mixture of Al203 and MgO was suggested, but the mixture ratio of the oxides was not confirmed. In addition, it has been found that the zirconia ceramic composition proposed in the former publication is not useful to enhance the thermal stability, whereas the zirconia ceramic composition proposed in the latter publication is not useful to enhance the strength.

The present invention has now found that the strength of partially stabilized zirconia ceramics is greatly influenced by the mixture ratio of the oxides Al203 and MgO and that if the mixture ratio of the oxides is out of a predetermined extent, the bending strength of the partially stabilized zirconia ceramics may not be increased. It is, therefore, a primary object of the present invention to provide a partially stabilized ziroconia ceramic superior in bending strength, acid resistance and thermal stability on a basis of determination of an optimal mixture ratio between the oxides.

According to th. pre.ent invention there j.sprovided a high strength zirconia r-aTn-c composition consisting essent of a compound of ZrO 2 containing n 5.0ol% Y0 as a ti-izer-an-- 4 iz) i i -J ,i i ii I il l 4 The present invention therefore provides a pressureless sintered zirconia ceramic composition comprising a compound of ZrO comprising 0.5-5.0 mol% Y 0 as a stabilizer and 1-30 wt% aluminum and magnesium contents to the amount of said compound of ZrO 2 in terms of Al 2 0 and MgO, wherein a molar ratio between the aluminum and magnesium contents is selected from one of the following ranges in terms of A1, 0 and MgO: 35-45/65-55 60-75/40-25 85-99/15-1. Preferably the compound of ZrO 2 contains 1.5-5.0 mol% Y 20 as a stabilizer and the compound of ZrO 2 contains 1-5 wt% aluminum and magnesium contents to the amount of said compound of ZrO 2 in terms of Al 0 and MgO.

The invention also provides a pressureless sintered zirconia composition comprising a compound of ZrO 2 comprising 0.5-5.0 mol% Y20 and 0.5-12 mol% CeO 2 as stabilizers and 1-30 wt% aluminum and magnesium contents to the amount of said compound of Zr 2 in terms of Al 03 and ;MgO, the total amount of Y 2 0 and CeO 2 being 1.0-15 mol%, wherein a molar ratio between the aluminum and magnesium contents is selected from one of the following ranges in terms of Al 0 and MgO: 35-45/65-55 60-75/40-25 85-99/15-1. Preferably the compound of ZrO 2 contains 1-6 wt% aluminum and magnesium contents to the amount of said compound of ZrO 2 in terms of Al 03 and MgO. i 5 IAS:EK(12:49) -1 b- Preparation of raw materials for the zirconia ceramic composition can be made by a method of mixing oxide powder of alumina-magnesia system or spinel powder with zirconia powder, a method of mixing each powder of alumina and magnesia witn zirconia powder, a method of obtaining powder from aqueous solutions of ions of zirconium, yttrium, aluminum, magnesia and the like by means of wet mixing method. Preferably, the following two methods are adapted to preparation of the raw materials for the zirconia ceramic composition. In a primary preparation method, either mixed powder of Al 2 0 3 -MgO or aqueous salt solutions of Al20 3 -MgO is added to mixed powder of ZrO 2 -Y 203 or ZrO2-Y 203-CeO2' In a secondary preparation method, either powder or aqueous salt solution of MgO is added to mixed powder of ZrO2-Y 0 -Al23 or ZrO -Y203-CeO2-Al203. In these preparation methods, ZrO 2

-Y

2 0 3 ZrO 2

-Y

2 0 3 -CeO 2 ZrO2-Y203-A203, ZrO2-Y203--CeO2-Al20 each may be prepared in the form of mixed powder thereof or may be prepared by calcination of mixed powders thereof.

Although 0.5 3.0 wt% Hfo 2 is inevitably contained in the zirconia raw material, a part of ZrO 2 may be substituted for Hf0 2 in the zirconia ceramic composition of the present invention.

6 For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:- Fig. 1 is a graph illustrating bending strength and acid resistance of the zirconia ceramic composition in relation to molar ratios of Al 203 and MgO in the case that the mixture ratio of aluminum and magnesium contents to the whole contents of the zirconia ceramic composition in terms of Al 03 and MgO was determined in a constant value; Fig. 2 is a graph illustrating bending strength and acid resistance of the zirconia ceramic composition in relation to weight ratios of Al 203 and MgO to the whole contents of the zirconia ceramic composition in the case that the molar ratio between aluminum and magnesium contents was determined in a constant value; Fig. 3 is a graph illustrating bending strength of the zirconia ceramic composition in relation to a mixed amount (mol%) of Y 2 0 3 in the composition; Fig. 4 is a graph illustrating bending strength of the zirconia ceramic composition in relation to a mixed amount (mol%) of CeO 2 in the composition; Fig. 5 is a graph illustrating bending strength of the zirconia ceramic composition in relation to a mixed amount of aluminum and magnesium contents in 7 i~Z 1, terms of Al203 and MgO in the composition; Fig. 6 is a graph illustrating bending strength Iof the zirconia ceramic composition in relation to a j molar ratio of Al203 and MgO in the composition; and Fig. 7 is a graph illustrating the rate of transformation from cubic structure into tetragonal structure and to monoclinic structure in relation to a mixed amount (mol%) of CeO 2 and Y 2 0 3 in the zirconia ceramic composition.

Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the drawings.

EXAMPLE 1 A compound of ZrO 2

-Y

2 0 3 was precipitated by hydrolysis of aqueous salt solutions thereof. The precipitated compound was calcined at 900 C to obtain zirconia powder of particle diameter less than 1l)m. The zirconia powder was added with powder of Al203 and MgO, ground by a pot mill and dried by spray 20 to obtain a raw material consisting essentially of ZrO -Y 0 -Al -MgO.

rO2 203-A 2 0 3 -MgO.

The raw material was preformed under pressure of 200 kg/cm 2 and shaped by Cold Isostatic Pressing into 8 a a rectangular plate of 60 x 60 x 8 (mm) under pressure of 3 ton/cm 2 The rectangular plate was fired by pressureless sintering at about 1400 0 C for 5 hours and cut into a plurality of bar specimens each size of which is 3 x 4 x 40 Thus, the bar specimens were tested as follows.

The bending strengths were measured by 4-point bending test with 10mm upper span and 30mm lower span at a cross-head speed 0.5mm/min using the bar specimens.

For measurement of the acid resistances, the bar specimens were put into solution of 36 wt% HC1 in a sealed container and retained in the solution at 150 0 C for 200 hours. Thereafter, the weight of bar specimens was measured to calculate reduction of the weight per a unit area (mg/cm2).

The test results of the bar specimens are shown in Tables 1 and 2 attached hereto and illustrated in Figs. 1 and 2. The test results of No. 1 No. 27 shown in Tables 1 and 2 were obtained in the case that a molar ratio between A1 2 0 3 and MgO or an added amount of Al 203 and MgO was varied in a condition where the molar ratio of a stabilizer Y 2 0 3 to the compound ZrO 2 was determined in a constant value The data of Fig. 1 was obtained by variation of the molar ratio between Al 2 0 3 9 and MgO in a condition where the added amount of Al 203 and MgO was determined in a constant value (2 The data of Fig. 2 was obtained by variation of the added amount of il203 and MgO in a condition where the molar ratio between Al 2C 3 and MgO was determined in a constant value (40/60, 70/30, 90/10). In Figs. 1 and 2, a dot-dash straight line indicates the bending strength and acid resistance of a bar specimen prepared without Al203-MgO. As is illustrated in Figs. 1 and 2, the acid resistance of the bar specimens added with Al 203 and MgO was noticeably enhanced in the case that the molar ratio between Al 203 and MgO was determined more than 30/60, and the bending strength of the bar specimens was increased up to a peak value in the case that the molar ratio between Al 2 0 3 and MgO was determined to be 40/60, 70/30 and 90/10, respectively. Particularly, the bending strength of the bar specimens was noticeably increased in the case that the molar ratio between Al 203 and MgO was determined to be 35 45/65 55, 60 75/40 25, 85 99/15 1, respectively. In addition, the bending strength was increased in the case that the Sadded amount of Al203 and MgO was determined to be less than 20 wt%, preferably less than 10 wt%.

The test results of No. 28 No. 43 shown in Table 2 were obtained in the case that the molar ratio L between Al 203 and MqO was varied in a condition where the molar ratio of a stabilizer Y 0 to the compound ZrO was determined in a constant value (1.5/98.5, 2/98, 5/95) and where the added amount of Al 203 and MgO was determined in a constant value (2 wt%, 5 The test results of No. 28 No. 43 indicate that the bending strength and acid resistance of the bar specimens weie enhanced in contrast with the bar specimen prepared without Al 2 0 3 and i.igO.

From the test results described above, it will be understood that the zirconia cermaic composition of the present invention is superior in bending strength and acid resistance and useful as mechanical structure materials. In Example 1, Al 203 and MgO were adapted to contain aluminum and magnesium contents into the compound of Zr0 2

-Y

2 O. The amount of the aluminum and magnesium contents is consistent with an amount of aluminum and magnesium contents in a ceramic composition ground in 44/t<m after firing and measured by fluorescent X-ray analysis. For this reason, the amount of aluminum and magnesium contents in terms of Al 0 and MgO is substantially consistent with the added amount of A 1203 and MgO. In addition, it was found by fluorescent X-ray analysis that the following impurity is contained in the bar specimens.

11 .iz\ less than 2.0 wt% SiO 2 less than 2.0 wt% TiO2, less than 0.5 wt% CaO, less than 0.5 wt% K20, less than 0.5 wt% Na20 and less than 3.0 wt% HfO 2 EXAMPLE 2 A compound of ZrO2-Y203-CeO2 was precipitated by hydrolysis of aqueous slat solutions thereof. The precipitated compound was calcined at 900 C to obtain zirconia powder of particle diameter less than 1/Am. The zirconia powder was added with powder of Al 203 and MgO, ground by a pot mill and dried by spray to obtain a raw material consisting essentially of ZrO2-Y203-CeO -Al 0 -MgO.

The raw material was preformed under pressure of 200 kg/cm? and shaped by Cold Isostatic Pressing into a rectangular plate of 60 x 60 x 8 (mm) under pressure of 3 ton/cm 2 The rectangular plate was fired by 0 pressureless sintering at about 1400 C for 5 hours and cut into a plurality of bar specimens each size of which is 3 x 4 x 40 Thus, the bar specimens were tested as follows.

The bending strengths were measured by 4-point bending test with 10mm upper span and 30mm lower span at a cross-head speed 0.5mm/min using the bar specimens.

12 t For measurement of the thermal deterioration, the bar specimens were put into hot water at 250°C under vapor pressure of 39 kg/cm 2 in an autoclave and treated by heat for 50 hours. Thereafter, the rate of transformation from cubic structure into tetragonal structure and to monoclinic structure in the Ij bar specimens were calculated as follows.

The bar specimens were mirror surface finished with diamond paste and applied to X-ray diffraction to measure integration intensity IM, IT, IC of diffraction peaks on the monoclinic crystal surface (111), the tetragonal crystal surface (111) and the cubic crystal surface thereby to calculate an amount of tetragonal and cubic contents V 0 (IT IC)/(IM IT IC). The bar specimens after heat treatment were further applied to X-ray diffraction to calculate an amount of tetragonal and cubic contents (V1 in the same manner as described above. Thus, the rate of transformation (V 0

VI)/V

0 x 100 was calculated on a basis of the calculated amounts of tetragonal and cubic contents V 0 and V The test results of the bar specimens are shown in Tables 3-11 attached hereto and illustrated in Figs.

3-7. In the test results, the value of 70 kgf/mm 2 was defined as a standard value for determination of the 13 bending strength, and the value of 25% was defined as a standard value for determination of the thermal stability. In Fig. 3, the specimens in eight groups A H are plotted near or below the standard value 70 kgf/mm 2 The specimens in groups A 1 were prepared to contain less than 82-85 mol% ZrO2 and more than mol% Y 2 0 3 and Ce0 2 the specimens in groups E and F to contain 85 mol% ZrO 2 and 15 mol% Y203 and CeO2, the specimens in group G to contain 5 mol% Y203 and the specimens in group H to contain 7 mol% Y203. In Fig. 4 there is illustrated a relationship between a mixed amount of CeO 2 (mol%) in a zirconia ceramic composition containing 3 mol% Y203 and 2 wt% Al203 and MgO and bending strength of the same ceramic composition. In this illustration, it was found that the bending strengths are decreased in accordance with an increase of the mixed amount of CeO 2 and noticeably decreased by mixture of CeO 2 more than 12 mol%. From the test results described above, it was confirmed that a high strength zirconia cermaic composition can be obtained by a compound of ZrO 2 containing 0.5 5 mol% Y 2 0 3 0.5 t 12 mol% CeO 2 Al 2 0 3 and MgO, provided that the total amount of Y203 and CeO 2 should be determined to be 1.0 mol%.

14 t' In Fig. 5 there is illustrated a relationship between a mixed amount of Al203 and MgO in a zirconia ceramic composition containing 3 mol% Y 2 0 3 and 2 mol% CeO2 and bending strength of the same ceramic composition. In this case, the mixed amount of aluminum and magnesium contents was determined in terms of Al203 and MgO. In this illustration, it was found that the bending strengths are decreased in accordance with an increase of the mixed amount of Al 2 03 and MgO and noticeably decreased by mixture of Al203 and more than 30 wt%. In Fig. 6 there is illustrated a i relationship between a molar ratio Al 2 0 3 /MgO in a zirconia ceramic composition containing 3 mol% Y203 2 mol% CeO 2 and 2 wt% Al203 and MgO and bending strength of the same ceramic composition. In this illustration, it was found that each peak of the bending strengths is obtained by determiation of the molar ratio Al 2 0 3 /MgO in 40/60, 70/30 or 90/10. Preferably, the molar ratio Al 2 0 3 /MgO should be determined in a extent of 35 45/65 55, 60 75/40 25 or 85 99/15 1. From the test results, it was confirmed that a high strength zirconia ceramic composition can be obtained by a compound of ZrO 2 containing less than 30 wt% Al203 and MgO at the molar ratio listed below.

35 45/65 60 75/40 85 99/15 1 15 As is understood from the data of Figs. 3-5, it was confirmed that the bending strength is noticeably increased in a zirconia ceramic composition containing 2 mol% Y203, less than 5 mol% CeO2, 1 5 mol% A1203 and MgO. In Fig. 7 there is illustrated a relationship between mixed amounts (mol%) of Y 2 0 3 and CeO 2 in a zirconia ceramic composition containing 2.0 wt% at a molar ratio 90/10 and the rate of transformation of the tetragonal structure and cubic structure in the ceramic composition. From the data of Fig. 7, it was confirmed that the rate of transformation is decreased in accordance with an increase of the mixed amounts of Y203 and CeO 2 This means that the thermal stability of the zirconia ceramic composition is greatly enhanced by an increase of the mixed amounts of Y 2 03 and CeO2' EXAMPLE 3 Powders of ZrO2-Y200 and ZrO2-203-Ce02 were prepared in the same manner as describeu in Example 1 added with aluminum and magnesium contents in the form of Al(OH) 3 A1C1 3 Al(N0 3 3 A1 2

(C

2 0 4 3 or the like and Mg(OH) 2 MgCl 2 Mg(NO 3 2 MgC 2 0 4 MgCO 3 or the like, ground by a pot mill and dried by spray to obtain a raw material consisting essentially of ZrO 2 -Y 203 and the aluminum and magnesium contents and a raw material consisting essentially of ZrO 2

-Y

2 0 3 -CeO 2 and the aluminum and magnesium contents.

16 Using the raw materials, various bar specimens were prepared in the same manner as described in Example 1 and tested in the same manner as described in Example 1. The test results of the bar specimens are shown in Tables 12-15 attached hereto. From the data of Tables 12-15, it was confirmed that the use of aluminum and magnesium contents in the form of the above-described compounds is effective to obtain the same results as those in use of Al203-MgO.

2 3 EXAMPLE 4 Sol-solution was prepared by hydrolysis of aqeous solution containing zirconium oxychloride added with yttrium chloride or yttrium chloride and cerium chloride. The sol-solution was added with Al(OH) and 3 Mg(OH) 2 treated by heat, ground and dried in the same Smanner as described in Example 1 to obtain a raw material.

i The sol-solution was added with Al(OH) 3 in such a manner that a moirr ratio to MgO is determined to be 90/10 in terms of Al203. Powder obtained by heat it treatment of the sol-solution was added with powder of MgO, ground and dried in the same manner as described in Example 1 to obtain a raw material.

17 Using the raw materials, various bar specimens were prepared in the same manner as described in Example 1 and tested in the same manner as described in Example 1. The test results of the bar specimens are shown in Table 16 attached h-reto. From the data of Table 16, it was confirmed that the use of zirconium, yttrium and cerium ions in the form of aqueous salt solution is effective to obtain the same results as those in use of 0 precipitated ZrO 2

-Y

2 0 3 or ZrO 2

-Y

2 0 -CeO 2 o1 a 0 18t,' Table 1 Molar Patio AlOM Bedn Acid No 23MoStrength Resistance (Y 0 /ZrO)Moa ao ot() (kgf/ur 2 (mg/Cn 2 1 3/97 20/80 2 52.0 36.4 2 3/97 30/70 2 71.2 3 3/97 40/60 2 99.4 4 3/97 50/50 2 69.2 3.6 3/97 55/45 2 70.4 6 3/97 70/30 z 105.2 3.1~ 7 3/97 80/20 z 72.3 8 3/97 90/10 2 110.5 9 3/97 100/ 0 2 50.1 3.Z 3/97 40/60 1 98.7 11 3/97 40/60 5 98.2 2.7 12 3/97 40/60 10 90.5 2.7 13 3/97 40/60 20 87.8 2.6 14 3/97 40/60 30 84.5 3/97 70/30 1 99.5 16 3/97 70/30 5 103.0 17 3/97 70/30 10 95.Z 2.9 18 3/97 70/30 20 89.8 2.9 19 3/97 70/30 30 84.8 2.6 3/97 90/10 1 99.2 5.1 21 3/97 90/10 5 102.0 3.1 L22 1 3/97 90/10 10 1 95.4 1 3.1 Table 2 Moa aiAl 0 /M90 Bending Acid No (Yolar 2ati Strength Resistance

(Y~

3 /z 2 )Molar Ratio Amnount (kfirr 2 (/cm 2 2i3 3/97 90/10 20 90.2 2.9 24 3/97 90/10 30 85.2 2.7 3/97 30/70 5 67.7 28.1 2.6 3/97 50/50 2.0 51.3 3.7 27 3/97 0 92.0 73.1 28 1.5/98.5 40/60 2 78.2 52.1 29 1.5/98.5 70/30 2 78.2 45.0 1.5/98.5 90/10 2 77.2 41.0 31 1.5/98.5 0 62.0 120.2 32 2/98 40/60 2 98.7 37.0 33 Z/98 70/30 2 98.5 37.0 34 Z/98 90/10 2 100.0 36.8 2/98 100/ 0 2 52.1 32.0 36 2/98 40/60 5 99.0 35.0 37 2/98 70/30 5 102.1 36.5 38 2/98 90/10 5 106.0 36.2.

39 2/98 0 90.5 92.1 5/95 40/60 2 79.2 32.0 41 5/95 70/30 2 78.8 29.0 42 5/95 90/10 2 79.5 38.7 43 5/95 1 1 0 58.5 122.4 i I1)10 e I r, s

P

r Table 3 Composition A1 2 0 3 -MgO Bending Trans- No ZrO2 y203 CeO2 Strength formation (mol%) (mol%) (mol%) A1 2 0 3 /MgO Amount (Kgf/mm2) Rate (molar ratio (wtg) 1 99.5 0.5 0 40/60 2 Degradated 2 89.5 i 10.0 75.5 21 3 85.0 a 14.5 84.5 7 4 82.5 i 17.0 a 45.0 4 99.5 0 70/30 Degradated 6 89.5 10.0 74.8 18 7 85.0 14.5 85.3 7 8 82.0 17.0 52.1 4 9 99.5 a 0 90/10 Degradated 89.5 10.0 78.3 18 11 85.0 14.5 87.5 7 12 82.5 17.0 49.8 3 13 98.0 2.0 0 40/60 2 98.7 Degradated 14 95.0 3.0 92.5 93.0 5.0 87.0 16 85.0 13.0 74.0 17 82.0 16.0 a 47.3 4 18 98.0 0 70/30 a 98.5 Degradated 19 95.0 3.0 93.7 27 93.0 5.0 97=5 21 85.0 13.0 72.1 4 Z 82.0 16.0 48.5 4 -I I Table 4 CapoitnAl 2 0 3 -1149 Bending Trans- No Zro 2 Y203 CeO 2Strength formation (mol%) A 0ml) /g Amount (ygf/rni 2 Rate(% (m ola r ratio' (wLt 23 98.0 2.0 0 90/10 2 106.0 24 9o5.0 3.0 Z/ I 97.3 28 93.0 5.0 13 26 85.0 13.0 78.3 27 82.0 16.0 52.1 4 28 97.0 3.0 0 40/60 12 98.7 39 29 96.5j 0.5 94.2 31 96.0 1.0 41__ 94.5 22 31 95.0 Zi .0 92.1 17 32 94.0 3.0 89.9 14 33 92.0 ii5.0 87.4 8 34 87.0 ii10.0 73.1 4 85.0 Af 12.0 71.1 4 36 83.0 14.0 47.0 4 37 97.0 0 70/30 102.1 37 38 96.5 ii0.5 98.5 39 96.0 1.0 97. 8 24 95.0 2.0 Af97.8 18 41 94.0 3.0 3.0 70/30 2 95.3 142 92.0 15.0 89.0 8 43 87.0 10.0

I

Table Composition SBending Trans- No ZrO2 203 CeO2 2 0 3 Strength formation (mol%) 203/

M

gO Amount (Kgf/,n 2 Rate (molar ratio( (wt%) 44 85.0 3.0 12.0 70/30 2 70.1 4 83.0 14.0 53.4 4 46 97.0 0 90/10 115.0 39 47 96.5 0.5 110.2 27 48 96.0 1.0 i 100.5 49 95.0 2.0 i, 109.4 21 94.0 3.0 a/ 98.7 17 51 92.0 5.0 1 97.2 52 87.0 10.0 80.5 53 85.0 12.0 72.1 54 83.0 /1 14.0 n 57.2 4 94.5 5.0 0.5 40/60 2 73.2 12 56 93.0 2.0 70.5 3 57 94.5 /1 0.5 70/30 74.2 11 58 93.0 /1 2.0 1 74.7 3 59 94.5 /i 0.5 90/10 76.2 93.0 2.0 1 75.3 3 61 92.5 7.0 0.5 40/60 2 56.2 7 62 91.0 I1 2.0 ,1 44.5 3 63 92.5 0.5 70/30 55.3 7 64 91.0 2.0 11 45.5 3 92.5 90/10 56.4 7 i

S:

0 2 000 V0 Table 6 Cpsition c sition ABending Trans- No ZrO2 y 203 CeO 2

A

2 0 3 -0 Strength formation (mol%) (mol%) (mol%) Al 2 0 3 /MgO Amount (Kgf/rm 2 Rate (molar ratio (wt%) 66 91.0 7.0 2.0 90/10 2 48.2 3 67 97.0 3.0 0 40/60 1 98.7 42 68 95.0 2.0 92.8 69 94.0 3.0 95.2 19 92.0 /i 5.0 87.1 9 71 85.0 12.0 72.3 72 83.0 14.0 a 54.2 4 73 97.0 0 70/30 99.5 41 74 95.0 2.0 92.1 24 94.0 3.0 92.4 19 76 92.0 5.0 91.2 7 77 85.0 12.0 71.5 78 83.0 14.0 53.1 79 97.0 0 90/10 99.2 39 95.0 2.0 96.5 24 81 94.0 3.0 93.7 82 92.0 5.0 89.0 7 83 85.0 7 12.0 73.2 84 83.0 14.0 58.5 97.0 3.0 0 40/60 5 98.2 32 86 95.0 2.0 L 1 95.6 -Y j .i /2 Table 7 Compsitin A10 L~fI Bending Trans- Zr YO0 CeD Strength formation No 2 2 3 Ce 2 AlO Amun Pg/m2 ate(% (mol%) (mol%) (mol%) 2mla ratio~ Amout 87 94.0 3.0 3.0 40/60 5 93.4 11 88 92.0 5.0 85.1 9 89 85.0 //12.0 70.2 83.0 14.0 60.0 4 91 97.0 0 70/30 103.0 92 95.0 ii2.0 97.3 23 93 94.0 3.0 95.2 94 92.0 5.0 90.0 8 85.0 /,12.0 74.1 96 83.0 14.0 I,58.0 4 97 97.0 0 90/10 102.0 32 98 95.0 ii2.0 100.3 23 99 94.-0 3.0 98.6 12 100 92.0 5.0 89.4 8 101 85.0 12.0 78.5 102 83.0 14.0 61.0 4 103 97.0 0 40/60 1 C 90.5 104 95.0 2.0 88.2 17 105 92.0 ;Y5.0 72.1 106 85.0 12.0 67.5 4 107 83.0 414.0 444.3 4 108 97.0 0 70/30i 95.2 109 95.0 2.0 89.5 14 0 c oo C C Table 8 Ccimposition No ZrO2 Y203 CeO2

A

2 0 3 -MO Bending Trans- (mol%) (mol%) (mol%) Al 2 0 3 /MgO Amount (Kgf/ rmate (ion%) (molar ratio) (wt%) 110 92.0 3.0 5.0 70/30 10 72.1 4 111 85.0 12.0 1 65.5 4 112 83.0 14.0 50.9 3 113 97.0 0 90/10 95.4 24 114 95.0 2 91.3 12 115 92.0 5.0 n 80.2 6 116 85.0 a 12.0 74.4 4 117 83.0 I 14.0 57.5 4 118 97.0 3.0 0 40/60 20 87.8 119 95.0 2.0 a 84.5 12 120 92.0 5.0 I 74.7 121 85.0 12.0 58.2 3 122 33.0 14.0 60.0 3 123 97.0 a 0 70/30 89.8 21 124 95.0 a 2.0 a 89.2 14 125 92,0 i 5.0 72.2 4 126 85.0 12.0 60.3 3 127 83.0 14.0 a a 54.1 4 128 97.0 a 0 90/10 90.2 18 129 95.0 2.0 i 87.2 130 92.0 5.0 a 74.2 131 85.0 j 12,0 57.6 4 0

-U

c,0o a C Table 9 Composition Al 2 0 3 -MgO Bending Trans- No ZrO 2

Y

2 0 3 CeO 2 Strength formation (mol%) (mol%) (mol%) Al203A4gO Amount (Kgf/nn 2 zaLe molar ratio) (wt%) 132 83.0 3.0 14.0 90/10 20 56.1 4 133 97.0 0 40/60 30 84.5 17 134 95.0 i, 2.0 82.1 12 135 92.0 5.0 i 69.2 136 85.0 12.0 62.1 3 137 83.0 14.0 a 49.5 3 138 97.0 '0 70/30 84.8 18 139 95.0 2.0 i 82.1 14 140 92.0 a, 5.0 ii 70.3 3 141 85.0 12.0 64.3 3 142 83.0 14.0 51.2 3 143 97.0 i, 0 90/10 86.4 18 144 95.0 2.0 84.2 9 145 92.0 5.0 74.7 4 146 85.0 12.0 67.4 3 147 83.0 I, 14.0 52.5 3 148 97.0 3.0 0 40/60 40 72.2 149 95.0 2.0 67.2 150 92.0 5.0 56.8 151 85.0 12.0 55.0 4 152 83.0 14.0 a 47.0 3 153 97.0 0 70/30 i, 73.4 13 2 Table Ca' ;osition o Zro 2 Y 0 3 CeO 2

A

2 0 3 M90o Bending Trans- No 2 3 2Strength formation Cmol%) (mol%) Al 2

O

3 /MgO Amount (Kgf/rm 2 Rate ratio) (wtO) 154 95.0 3.0 2.0 70/30 40 68.5 155 92.0 5.0 I 58.2 156 85.0 12.0 //54.2 3 157 83.0 14.0 //48.7 3 158 97.0 1/0 90/10 76.7 16 159 95.0 74.2 12 160 92.0 5.0 -55.2 161 85.0 12.0 58.5 3 162 83.0 14.0 /,49.2 3 163 p;5. 0 3.0 2.0 30/70 Z.0 67.5 32 164 35/65 ii 86.8 24 165 //45/55 80.7 13 166 1 i50/50 65.8 167 It 60/40 88.7 12 168 75/25 81.2 12 169 Z/ 80/20 i 68.2 12 170 85/15 84.9 14 171 99/ 1 89.5 172 /1 100/ 0 77.0 173 1 85.0 0.5 10.0 0 57.2 174 1 93.5 2.0 j 5.0 1172.0 1 13 6- _A69

I'

0 goo Table 11 Canpcsition NooY CeO 2 A1 2 0 3 -Mgo Bending Trans- No 2 Strength formation (nol%) (Mol%) (mol%) Al 2

O

3 44gO Amount (Kgf/mnm 2 Rate (molar ratio) (wt%) 175 95.0 3.0 2.0 -0 68.7 23 176 94.0 5.0 1.0 -62.1 4 r: i 0 0- 0 s 00.

0 0 CP 0r 0 00j tQ., 4 0 0 00, 0 0 0 0 0o o 0 0 0 0

J

Table 12

~VJ

o LXIBending Acid No Z Addition A1203-M9 Strength Resis- 2 2 3 2 (Kgf/rm 2 tance (mol%) (mOl%) (iol%) Al ccmpound Mg compound m 2 0 3 AgO Amount mlar ratio) (mg/cm 1 97.0 3.0 0 AI(OH) 3 Mg(OH)2 40/60 2.0 100.5 3.2 2 i 5.0 105.1 3 A l I 20.0 92.1 2.1 4 Z/ #1 30.0 85.2 ii 40.0 65.2 2.9 6 If 70/30 2.0 105.2 7 Af /1 5.0 109.2 2.1 8 ii ii II 20.0 93.1 2.1 9 Al fi 30.0 87.8 Af 40.0 68.3 3.2 11 "1 90/10 2.0 125.0 12 if 5.0 115.0 3.1 13 20.0 95.0 3.1 14 Af 30.0 90.0 Z/ 40.0 75.7 2.8 16 95.0 5.0 0 AICI 3 M9CI 2 40/60 2.0 78.2 30.0 17 /1 70/30 76.5 25.3 18 A, /f 90/10 78.2 27.5 19 97.0 3.0 0 i 40/60 98.5 3.2 5.0 97.9 21 I 70/30 2.0 110.5 3.4 22 ii/ 5.0 109.5 2.2 a aI Table 13 Ccaposition Bending Acid Addition A1203-'W Stength Resis- No CO streng h tance 2l m 3m2Al cnpound Mg canpound A1 2 0 3 /MgO Amount (Kf, (man 2 molar ratio) (wt%) 23 97.0 3.0 0 AICI 3 M9CI 2 90/10 2.0 119.2 24 5.0 108.2 I AI(0H) 3 MgCI 2 40/60 2.0 107.2 2.8 26 Af 70/30 118.5 27 Af ii i 90/10 119.5 28 f i AI(N0 3 3 Mg(N0 3 )2 ii 108.2 2.1 29 A1 2

(C

2 04) 3 M9C 2

O

4 I' 122.7 2.2 AI(N0 3 3 HgC 2

O

4 105.6 31 W AI(OH) 3 MgCO3 'I 32 I' I' AI(OH) 3 M9(OH) 2 30/70 2.0 72.2 32.1 33 65.3 3.6 34 80/20 60.2 3.2 I I I 100/ 0 72.3 36 A1CI 3 MgC1 2 30/70 68.5 40.3 37 1 50/50 1 62.1 4.2 38 80/20 63.4 3.2 39 100/ 0 68.5 If AI(N0 3 3 Hg(N0 3 2 50/50 65.1 4.2 41 ii AI(OH) 3 MgCO 3 64.2 42 95.0 2.0 AI(OH), M9(OH) 2 40/60 93.2 I a~iiii~:; i Table 14 Composition Addition A1 2 0 3 -MgO Bending Acid No ZrO 2 203 CeO 2 Strength Resistance (mol%) (mol%) (mol%) Al ccapound Mg cmpound Ao203gO AMount (Kgf/mr2) (mg/m 2 (molar ratio) (wt%) 43 95.0 3.0 2.0 AI(OH) 3 Mg(0H) 2 40/60 5.0 92.1 44 A l 20.0 86.5 I j 30.0 87.1 12 46 i 40.0 58.8 4 47 a i a70/30 2.0 101.2 48 i i i 5.0 97.5 49 N a a a a 20.0 92.1 #a I Q 30.0 83.2 51 a 1 40.0 60.2 52 a a Il 90/10 2.0 112.1 21 53 a a a 5.0 105.2 17 54 1/ a i a 20.0 92.7 12 30.0 84.0 56 a A a a a a 40.0 64.8 6 57 92.0 3.0 5.0 40/60 2.0 89.5 8 58 I f 70/30 92.1 59 /1 a a 90/10 96.5 8 95.0 2.0 a AIC1 3 MgC 2 40/60 2.0 90.5 61 I a a a 5.0 89.3 62 a a a 70/30 2.0 99.8 14 63 4 Z 4 5.0 98.2 18 v" 7- 77 4 oi Vg ,Table Ccnposition Addition M120 3 -M9o Bending Acid No Zro 2 CeO Strength Resistance 2 Y032 (yqf/jm2) (mg/cm2)) (mol%) (nol%) (mol%) Al canpound Mg ccanpound A1 2 0 3 /Mg0 Amount (molar ratio) (wA) 64 95.0 3.0 2.0 AICI 3 MgCI 2 90/10 2.0 108.2 21 ii i ii ii 5.0 103.1 18 66 ii ii AI(OH) 3 M9CI 2 60/40 2.0 91.2 18 67 70/30 96.5 68 it 90/10 105.0 69 AI(N0) 3 Mg(N0 3 2 98.4 18 A] a1 2

(C

2 0 4 3 HgC 2

O

4 ii 110.3 71 AI(N0 3 MgC 2 OA 108.2 72 ii i AI(OH), MCO 3 73 AI(OH) 3 Wg(OH) 2 30/70 2.0 65.2 37 74 Z/ #i 50/50 62.1 80/20 65.3 12 76 100/ 0 A/ 69.1 9 77 AIC1 3 gCI 2 30/70 1 64.4 34 78 50/50 67.1 79 'I 80/20 63.7 12 100/ 0 68.3 14 81 AI(N0 3 3 Mg(N0 3 2 50/50 67.2 21 82 Z/ AI(0H) 3 NgCO: 59.8 18 L ,a Ar.

I~

9 (f1

'S.

Table 16 ________Canposition Acid Zr 2 2 2 A1 2 0 3 -MgO Bending Resis- Trans- No Yr 0 e Strength tance formation (mol%) (mol%) (mol%) A12O 3 ,g0 mon (Kgf/mrn 2 (molar ratio) (wtO) 1 97.0 3.0 0 40/60 2.0 95.3 3.2- 2 iii /70/30 ii98.2 3.4- 3 90/10 99.4 3.4 4 95.0 3.0 2.0 40/60 ii 87.2 70/30 //92.1 -7 6 #/iii 90/10 92.5 8 7 97.0 3.0 0 90/10 2.0 107.5 2.7 8 Z/ Al A/ 115.7 9 95.0 3.0 2.0 125.3 14 i11.5 -17

Claims (4)

1. A pressureless sintered zirconia ceramic composition comprising a compound of ZrO 2 comprising 0.5-5.0 mol% Y 2 0 3 as a stabilizer and 1-30 wt% aluminum and magnesium contents to the amount of said compound of ZrO 2 in terms of Al 2 0 and MgO, wherein a molar ratio between the aluminum and magnesium contents is selected from one of the following ranges in terms of Al 0 and MgO:

35-45/65-55

60-75/40-25

85-99/15-1 2. The pressureless sintered zirconia ceramic composition of claim 1, wherein said compound of ZrO 2 contains 1.5-5.0 mol% Y 2 0 as a stabilizer. 0 o o oo° 3. The pressureless sintered zirconia composition of o claim 1 or 2, wherein said compound of ZrO 2 contains 1-5 wt% aluminum and magnesium contents to the amount of said Qo compound of Z'O 2 in terms of Al 20 3 and MgO. 4. A pressureless sintered zirconia composition comprising a compound of ZrO 2 comprising 0.5-5.0 mol% Y 2 0 and 0.5-12 mol% CeO 2 as stabilizers and 1-30 wt% aluminum and magnesium contents to the amount of said compound of o* ZrO 2 in terms of Al 2 0 3 and MgO, the total amount of Y 2 03 and CeO 2 being 1.0-15 mol%, wherein a molar ratio between the aluminum and magnesium contents is selected from one of the following ranges in terms of Al 20 and MgO: 35-45/65-55 60-75/40-25 85-99/15-1 /v" i k-, pl** I The pressureless sintered zirconia ceramic composition of claim 4, wherein said compound of ZrO 2 contains 1-5 wt% aluminum and magnesium contents to the amount of said compound of ZrO 2 in terms of Al 2 0 and MgO. 6. A pressureless sintered zirconia ceramic composition substantially as hereinbefore described with reference to any one of the Examples. DATED this 3rd day of July, 1990 N G K INSULATORS, LTD. WATERMARK Patent Trademark Attorneys, "The Atrium" 290 Burwood Road, Hawthorn, Victoria, 3122, AUSTRALIA. -36- IAS:EK(12:49) L -1