JPS6350308B2 - - Google Patents

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Publication number
JPS6350308B2
JPS6350308B2 JP58215835A JP21583583A JPS6350308B2 JP S6350308 B2 JPS6350308 B2 JP S6350308B2 JP 58215835 A JP58215835 A JP 58215835A JP 21583583 A JP21583583 A JP 21583583A JP S6350308 B2 JPS6350308 B2 JP S6350308B2
Authority
JP
Japan
Prior art keywords
oxide
zirconium oxide
crystals
sintered body
weight
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
JP58215835A
Other languages
Japanese (ja)
Other versions
JPS60108366A (en
Inventor
Takao Nakada
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Resonac Corp
Original Assignee
Hitachi Chemical Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Chemical Co Ltd filed Critical Hitachi Chemical Co Ltd
Priority to JP58215835A priority Critical patent/JPS60108366A/en
Publication of JPS60108366A publication Critical patent/JPS60108366A/en
Publication of JPS6350308B2 publication Critical patent/JPS6350308B2/ja
Granted legal-status Critical Current

Links

Description

【発明の詳細な説明】[Detailed description of the invention]

本発明は高強度、高温耐久性に優れた機械部品
などに用いられるジルコニア質焼結体(以下焼結
体という)に関する。 酸化ジルコニウムを主成分とする焼結体は熱伝
導率が低く、熱変形を起こしにくいため耐火断熱
材料として使用されてきた。最近はさらに酸化ジ
ルコニウムに安定化剤と称する酸化イツトリウ
ム、酸化カルシウム、酸化マグネシウムの一種又
は二種以上を少量固溶させると曲げ強さ、硬度等
が格段に向上することが知られ切削工具類に使用
されている。しかし高強度、高硬度の焼結体を得
るには気相、液相反応等により作製した極めて微
細な原料粉を使用したり、焼成温度を狭い範囲に
限定する必要がある。これは焼成物に含まれる結
晶の大きさおよび含有結晶種を限定する必要から
必然的に生じる条件である。そのため大型品の製
造は困難であり得られた製品も極めて高価なため
用途は限定されてしまう しかも、このようにして得られた焼結体は熱的
には不安定であり酸化イツトリウムを固溶した焼
結体は200〜500℃で、酸化カルシウムを固溶した
焼結体は1000℃近くで長時間の間には結晶が変化
し、強度低下するため熱的用途は制限を受けてし
まう。特に工業部品の用途にはダイアモンド研削
等により精密に研削加工を施す必要があるが、そ
の加工面は歪を大きく受けるため熱による結晶変
化がさらに起こりやすく強度低下する。 これに対し安定化剤を多量固溶させると熱的に
は安定になるが強度が低下してしまい機械部品と
しては不適当である。 本発明はかかる欠点のない焼結体を提供するこ
とを目的とするものである。 本発明者は上記の欠点について製造方法、化学
組成等を変え焼結体の性能の調査研究を進めた結
果、酸化ジルコニウムに酸化セリウムをある組成
範囲に固溶させた結晶の焼結体が機械的強度が高
く、耐摩耗性に優れ熱的安定性も良い焼結体が得
られることを確認した。 本発明は酸化ジルコニウムと酸化セリウムの固
溶体であり、かつ酸化ビスマスを含有した焼結体
において、該焼結体の結晶は酸化ジルコニウムに
酸化セリウムが固溶している正方晶酸化ジルコニ
ウム結晶が主であり、単斜晶及び/又は立方晶酸
化ジルコニウム結晶の含有量が全酸化ジルコニウ
ム結晶に対し20%以下であり、化学成分として酸
化ジルコニウム66〜87重量%、酸化セリウム12〜
27重量%及び酸化ビスマス0.05〜10重量%を含有
してなる焼結体に関する。 なお本発明において単斜晶及び/又は立方晶酸
化ジルコニウムの含有量は全酸化ジルコニウム結
晶に対し20%以下とされるが、結晶中に立方晶酸
化ジルコニウム結晶を含まず単斜晶酸化ジルコニ
ウム結晶が存在する場合は、その結晶付近での大
きな歪あるいはマイクロクラツクの発生を意味
し、結晶量が多くなると急激に強度低下するため
そのような場合は10%以下が望ましい。また結晶
中に単斜晶酸化ジルコニウム結晶を含まず、立方
晶酸化ジルコニウム結晶が存在する場合は酸化セ
リウム含有率が22重量%以上になると生成がX線
回折法で検出されるようになるが、この立方晶酸
化ジルコニウム結晶の含有率が多くなると熱的安
定性は良いが機械的強度が低下する。機械部品と
して望ましい強度を得るにはこの立方晶酸化ジル
コニウム結晶含有率は20%以下とされる。さらに
単斜晶酸化ジルコニウム結晶と立方晶酸化ジルコ
ニウム結晶とが同一焼結体中に含まれる場合は酸
化ジルコニウムと酸化セリウムの混合が不均一の
場合に起こり、この混合の不均一さは熱的不安定
性、機械強度低下を生じ望ましくない。以上の理
由により単斜晶及び/又は立方晶酸化ジルコニウ
ム結晶の含有量は20%以下とされる。 化学成分として酸化セリウムは12〜27重量%、
好ましくは16〜27重量%の範囲とされる。この範
囲とした理由は下記の試験によつて決定されたも
のである。 酸化ジルコニウム、酸化セリウム及び酸化ビス
マスを各種の比率に混合し、焼成して得られる固
溶体の焼結体を得、その性能を調査したところ、
酸化セリウムの含有率が12重量%以上から急激に
機械的強度が増加し、約17重量%で極大に達し、
その曲げ強さは約100Kg/mm2にもなり、従来セラ
ミツクスの最大とされる酸化イツトリウム―酸化
ジルコニウム系の強度に匹敵する値が得られた。 酸化セリウム含有率がさらに増加すると強度は
徐々に低下し、27重量%になるとアルミナ焼結体
で得られる値約50Kg/mm2になる。なお、50Kg/mm2
未満になると高強度の意味が失われる。また、こ
の焼結体の熱的安定性はダイアモンド切削で焼結
体から切り出した試料を室温から1300℃まで2
℃/分の昇温速度で上昇させ、1300℃に達成後2
℃/分の降温速度で下降させ、室温から室温に達
するまでの熱膨張率を測定し、かつ300〜1300℃
まで100℃きざみに設定した電気炉内に3000時間
放置し、そのときの結晶変化をX線回折法により
測定し、強度を3点曲げ試験法で評価した。この
結果、酸化セリウム含有率12重量%以上の焼結体
の熱膨張率は昇降温の差がなく、ほぼ直線的に変
化し、曲げ強さも50Kg/mm2以上であるが、12重量
%未満になると曲げ強さが極端に低下してくる。
また10重量%になると約300℃で急激に体積変化
し、曲げ強さはほぼ0であつた。 さらに酸化セリウム12〜16重量%未満では500
℃以下数百時間でダイアモンド研削面に単斜結晶
の生成、増加が認められた試験時間に伴うこれ以
上の変化は見い出せなかつた。また機械的強度の
変化は試験時間においては有意差はなかつた。 酸化ジルコニウムの含有率は酸化セリウムの含
有率の増減により決定され、酸化セリウムの上限
量27重量%のときは66重量%とされ、酸化セリウ
ムの下限量12重量%のときは87重量%とされる。 酸化ビスマスは焼結助剤として添加され、その
添加量は0.05〜10重量%の範囲とされ、0.05重量
%未満であると焼結助剤としての効果がなく、ま
た10重量%を越えると酸化ジルコニウム結晶の成
長を促進し、酸化ジルコニウム結晶が粗大化する
ため機械的強度のばらつきが大きくなる。 本発明における焼結体は上記組成物の他に不純
物としてSiO2,TiO2,FeO3等を2重量%以下含
まれていても差支えない。 以下実施例により本発明を説明する。 酸化ジルコニウム(第一希元素製、EPグレー
ド)と酸化セリウム(信越化学製純度、99.9%)
とを第1表に示す配合割合に秤量し、ボールミル
で平均粒径0.6μm以下になるまで湿式粉砕、混合
した。次に乾燥した後1250℃で1時間熱処理を行
ない、中間原料を得た。この中間原料に酸化ビス
マスを第1表に示す量添加し、再びボールミルで
平均粒径0.55μmになるまで湿式粉砕、混合した。
粉砕した泥漿にポリビニルアルコール(PVA)
およびワツクスを添加し、粉霧乾燥して成形粉を
得、さらに前記の成形粉を1トン/cm2の圧力にて
ラバープレス成形後1570℃で1時間焼成して焼結
体を得た。 次に前記の焼結体をダイアモンド砥石(200番)
を使用して四面研削し4×3×40mm寸法の試料を
得た。この試料を用いて各種試験を行なつた。な
お試験条件において試料に含まれる結晶量の測定
は焼成表面並びにダイアモンド研削面および粉砕
粉をX線回折装置を使用し、正方晶―立方晶の場
合、正方晶は(022)面、立方晶は(220)面で定
量し、また正方晶―単斜晶の場合、正方晶は
(111)面、単斜晶は(111)面と(111)面とで
定量した。含有成分量は螢光X線分折装置で、熱
膨張率は自記式熱分折装置で測定した。各試験結
果を合せて第1表に示す。
The present invention relates to a zirconia sintered body (hereinafter referred to as a sintered body) used for mechanical parts having high strength and excellent high-temperature durability. Sintered bodies containing zirconium oxide as a main component have low thermal conductivity and are resistant to thermal deformation, so they have been used as fire-resistant and heat-insulating materials. Recently, it has been known that bending strength, hardness, etc. are significantly improved when a small amount of one or more of yttrium oxide, calcium oxide, and magnesium oxide, which are called stabilizers, are dissolved in zirconium oxide. It is used. However, in order to obtain a sintered body with high strength and high hardness, it is necessary to use extremely fine raw material powder produced by gas phase or liquid phase reactions, or to limit the firing temperature to a narrow range. This is a condition that inevitably arises from the need to limit the size of crystals and crystal species contained in the fired product. For this reason, it is difficult to manufacture large products, and the products obtained are extremely expensive, limiting their uses.Furthermore, the sintered bodies obtained in this way are thermally unstable and contain yttrium oxide as a solid solution. The resulting sintered body is heated at 200 to 500°C, and the sintered body containing calcium oxide as a solid solution changes its crystal structure over a long period of time at nearly 1000°C, reducing its strength, which limits its thermal uses. In particular, for industrial parts applications, it is necessary to perform precision grinding using diamond grinding, etc., but the processed surface is subject to large distortions, which makes crystal changes more likely to occur due to heat, resulting in a decrease in strength. On the other hand, if a large amount of stabilizer is dissolved in solid solution, it becomes thermally stable, but the strength decreases, making it unsuitable for use as mechanical parts. The object of the present invention is to provide a sintered body free from such drawbacks. As a result of investigating and researching the performance of sintered bodies by changing the manufacturing method, chemical composition, etc. to address the above-mentioned drawbacks, the present inventors found that a sintered body of crystals in which cerium oxide was dissolved in zirconium oxide in a certain composition range was machined. It was confirmed that a sintered body with high physical strength, excellent wear resistance, and good thermal stability could be obtained. The present invention is a sintered body that is a solid solution of zirconium oxide and cerium oxide and contains bismuth oxide, and the crystals of the sintered body are mainly tetragonal zirconium oxide crystals in which cerium oxide is dissolved in zirconium oxide. Yes, the content of monoclinic and/or cubic zirconium oxide crystals is 20% or less of the total zirconium oxide crystals, and the chemical components are zirconium oxide 66-87% by weight and cerium oxide 12-12%.
27% by weight and 0.05 to 10% by weight of bismuth oxide. In the present invention, the content of monoclinic and/or cubic zirconium oxide is set to 20% or less of the total zirconium oxide crystal, but if the crystal does not contain cubic zirconium oxide crystal but contains monoclinic zirconium oxide crystal, If it exists, it means that there is a large strain or micro-cracks in the vicinity of the crystal, and as the amount of crystal increases, the strength decreases rapidly. In addition, if the crystal does not contain monoclinic zirconium oxide crystals but contains cubic zirconium oxide crystals, the formation can be detected by X-ray diffraction when the cerium oxide content exceeds 22% by weight. When the content of cubic zirconium oxide crystals increases, thermal stability is good, but mechanical strength is reduced. To obtain the desired strength for mechanical parts, the cubic zirconium oxide crystal content should be 20% or less. Furthermore, when monoclinic zirconium oxide crystals and cubic zirconium oxide crystals are contained in the same sintered body, this occurs when the mixing of zirconium oxide and cerium oxide is uneven, and this uneven mixing causes thermal instability. This is undesirable as it causes a decrease in quality and mechanical strength. For the above reasons, the content of monoclinic and/or cubic zirconium oxide crystals is set to 20% or less. As a chemical component, cerium oxide is 12 to 27% by weight,
Preferably it is in the range of 16 to 27% by weight. The reason for this range was determined by the following test. When zirconium oxide, cerium oxide, and bismuth oxide were mixed in various ratios and fired, a solid solution sintered body was obtained and its performance was investigated.
Mechanical strength increases rapidly when the content of cerium oxide exceeds 12% by weight, reaching a maximum at about 17% by weight.
Its bending strength was approximately 100 kg/mm 2 , a value comparable to the strength of the yttrium oxide-zirconium oxide system, which is considered the highest in conventional ceramics. As the cerium oxide content increases further, the strength gradually decreases, and at 27% by weight it reaches a value of about 50 Kg/mm 2 obtained with alumina sintered bodies. In addition, 50Kg/ mm2
If it is less than that, the meaning of high strength is lost. In addition, the thermal stability of this sintered body was confirmed by testing a sample cut from the sintered body by diamond cutting from room temperature to 1300°C.
Raise the temperature at a rate of ℃/min, and after reaching 1300℃ 2
The temperature was lowered at a cooling rate of ℃/min, and the coefficient of thermal expansion was measured from room temperature to room temperature, and the temperature was 300 to 1300℃.
It was left in an electric furnace set at 100°C increments for 3000 hours, and the crystal changes at that time were measured by X-ray diffraction, and the strength was evaluated by a three-point bending test method. As a result, the coefficient of thermal expansion of a sintered body with a cerium oxide content of 12% by weight or more changes almost linearly with no difference in temperature rise or fall, and the bending strength is also 50Kg/mm 2 or more, but less than 12% by weight. When this happens, the bending strength becomes extremely low.
Further, when the concentration was 10% by weight, the volume changed rapidly at about 300°C, and the bending strength was almost 0. Furthermore, if the cerium oxide is less than 12 to 16% by weight, 500
It was observed that monoclinic crystals formed and increased on the diamond-ground surface after several hundred hours at temperatures below ℃.No further changes were found with the test time. Furthermore, there was no significant difference in mechanical strength change over test time. The content of zirconium oxide is determined by increasing or decreasing the content of cerium oxide; when the upper limit of cerium oxide is 27% by weight, it is 66% by weight, and when the lower limit of cerium oxide is 12% by weight, it is 87% by weight. Ru. Bismuth oxide is added as a sintering aid, and the amount added is in the range of 0.05 to 10% by weight.If it is less than 0.05% by weight, it will not be effective as a sintering aid, and if it exceeds 10% by weight, it will oxidize. This promotes the growth of zirconium crystals and coarsens the zirconium oxide crystals, resulting in larger variations in mechanical strength. In addition to the above composition, the sintered body of the present invention may contain impurities such as SiO 2 , TiO 2 , FeO 3 or the like in an amount of 2% by weight or less. The present invention will be explained below with reference to Examples. Zirconium oxide (manufactured by Daiichi Kisensu, EP grade) and cerium oxide (manufactured by Shin-Etsu Chemical, purity 99.9%)
and were weighed in the proportions shown in Table 1, and wet-pulverized and mixed in a ball mill until the average particle size was 0.6 μm or less. Next, after drying, heat treatment was performed at 1250°C for 1 hour to obtain an intermediate raw material. Bismuth oxide was added to this intermediate raw material in the amount shown in Table 1, and the mixture was wet-milled and mixed again in a ball mill until the average particle size was 0.55 μm.
Polyvinyl alcohol (PVA) in crushed slurry
and wax were added thereto and spray-dried to obtain a molded powder.The molded powder was then rubber press molded at a pressure of 1 ton/cm 2 and then fired at 1570° C. for 1 hour to obtain a sintered body. Next, grind the sintered body using a diamond whetstone (No. 200).
A sample with dimensions of 4 x 3 x 40 mm was obtained by grinding on all sides. Various tests were conducted using this sample. Under the test conditions, the amount of crystals contained in the sample was measured using an X-ray diffraction device on the fired surface, diamond ground surface, and crushed powder. It was quantified using the (220) plane, and in the case of tetragonal-monoclinic, it was quantified using the (111) plane for tetragonal crystals, and the (111) plane and (111) plane for monoclinic crystals. The content of the components was measured using a fluorescent X-ray spectrometer, and the coefficient of thermal expansion was measured using a self-recording thermal spectrometer. The results of each test are shown in Table 1.

【表】 *印は本発明に含まれない範囲を示す。
なお試番7のものは焼成時の変形が大きかつた。
第1表から本発明になる焼結体は熱的安定性が
高く、機械的強度が高いことがわかる。 さらに焼結体の結晶組織を電子顕微鏡で観察し
た結果、酸化イツトリウム―酸化ジルコニウム系
の微細結晶あるいは酸化マグネシウム―酸化ジル
コニウム系の巨大な結晶とは大きく異なつてい
た。即ち結晶が緻密に、かつ均一に成長し、曲げ
強さ測定後の破面においては結晶径は1〜5μmで
あり極めて角ばつた結晶が隙間なく並び気孔は結
晶間に存在しているのが観察された。また酸化セ
リウム含有率が増加すると粗大な立方晶結晶が観
察されるようになり気孔も結晶内に存在してお
り、機械的強度と結晶組織とは極めて高い相関々
係が存在していることが確認された。 本発明になる焼結体は高強度、高温耐久性に優
れるため、エンジン部分、暖房機器、ガスバーナ
ーノズル、粉じんノズル等の機械部品に使用で
き、かつダイアモンド研削などによる影響がほと
んどなく、大型品の製造も可能であるなどの効果
を有する。
[Table] *marks indicate ranges not included in the present invention.
It should be noted that Sample No. 7 was highly deformed during firing.
It can be seen from Table 1 that the sintered body of the present invention has high thermal stability and high mechanical strength. Furthermore, when the crystal structure of the sintered body was observed using an electron microscope, it was found that it was significantly different from the fine crystals of yttrium oxide-zirconium oxide or the giant crystals of magnesium oxide-zirconium oxide. In other words, the crystals grow densely and uniformly, and the crystal diameter on the fracture surface after bending strength measurement is 1 to 5 μm, and the extremely angular crystals are lined up without gaps, with pores existing between the crystals. observed. Furthermore, as the cerium oxide content increases, coarse cubic crystals are observed, and pores also exist within the crystals, indicating that there is an extremely high correlation between mechanical strength and crystal structure. confirmed. The sintered body of the present invention has high strength and excellent high-temperature durability, so it can be used for machine parts such as engine parts, heating equipment, gas burner nozzles, dust nozzles, etc., and is hardly affected by diamond grinding, etc., and can be used for large-sized products. It has the advantage that it is also possible to manufacture.

Claims (1)

【特許請求の範囲】[Claims] 1 酸化ジルコニウムと酸化セリウムの固溶体で
あり、かつ酸化ビスマスを含有したジルコニア質
焼結体において、該ジルコニア質焼結体の結晶は
酸化ジルコニウムに酸化セリウムが固溶している
正方晶酸化ジルコニウム結晶が主であり、単斜晶
及び/又は立方晶酸化ジルコニウム結晶の含有量
が全酸化ジルコニウム結晶に対し20%以下であ
り、化学成分として酸化ジルコニウム66〜87重量
%、酸化セリウム12〜27重量%及び酸化ビスマス
0.05〜10重量%を含有してなるジルコニア焼結
体。
1. In a zirconia sintered body that is a solid solution of zirconium oxide and cerium oxide and contains bismuth oxide, the crystal of the zirconia sintered body is a tetragonal zirconium oxide crystal in which cerium oxide is dissolved in zirconium oxide. The content of monoclinic and/or cubic zirconium oxide crystals is 20% or less of the total zirconium oxide crystals, and the chemical components are zirconium oxide 66 to 87% by weight, cerium oxide 12 to 27% by weight, and bismuth oxide
A zirconia sintered body containing 0.05 to 10% by weight.
JP58215835A 1983-11-16 1983-11-16 Zirconia sintered body Granted JPS60108366A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP58215835A JPS60108366A (en) 1983-11-16 1983-11-16 Zirconia sintered body

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP58215835A JPS60108366A (en) 1983-11-16 1983-11-16 Zirconia sintered body

Publications (2)

Publication Number Publication Date
JPS60108366A JPS60108366A (en) 1985-06-13
JPS6350308B2 true JPS6350308B2 (en) 1988-10-07

Family

ID=16679050

Family Applications (1)

Application Number Title Priority Date Filing Date
JP58215835A Granted JPS60108366A (en) 1983-11-16 1983-11-16 Zirconia sintered body

Country Status (1)

Country Link
JP (1) JPS60108366A (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5684129B2 (en) 2009-08-21 2015-03-11 株式会社ノリタケカンパニーリミテド Zirconia sintered body, zirconia sintered body mixture for sintering, pre-sintered compact, and pre-sintered calcined body
JP5399949B2 (en) * 2010-03-02 2014-01-29 株式会社ノリタケカンパニーリミテド Zirconia sintered body, zirconia composition and zirconia calcined body
EP2371344A1 (en) * 2010-03-31 2011-10-05 Straumann Holding AG Body made of a ceramic material
JP5718599B2 (en) 2010-08-20 2015-05-13 株式会社ノリタケカンパニーリミテド Zirconia sintered body, and composition for sintering and calcined body

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