JPH08169752A - Aluminous sintered compact and its production - Google Patents
Aluminous sintered compact and its productionInfo
- Publication number
- JPH08169752A JPH08169752A JP6315051A JP31505194A JPH08169752A JP H08169752 A JPH08169752 A JP H08169752A JP 6315051 A JP6315051 A JP 6315051A JP 31505194 A JP31505194 A JP 31505194A JP H08169752 A JPH08169752 A JP H08169752A
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- JP
- Japan
- Prior art keywords
- alumina
- oxide
- dispersed phase
- sintered body
- crystals
- 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.)
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- Compositions Of Oxide Ceramics (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、強度、靭性に優れたア
ルミナ質焼結体およびその製造方法に関するもので、例
えば、航空・宇宙業界，精錬業界，化学業界で用いられ
たり、ガスタービンエンジン、自動車部品、切削工具材
料等に好適に使用されるアルミナ質焼結体およびその製
造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alumina sintered body having excellent strength and toughness and a method for producing the same, which is used, for example, in the aviation / space industry, refining industry, chemical industry, and gas turbine engine. The present invention relates to an alumina-based sintered body that is preferably used for automobile parts, cutting tool materials and the like, and a method for manufacturing the same.
【０００２】[0002]
【従来の技術】従来から、耐高温の構造部材として、ア
ルミナは耐環境性、高温強度ともに優れることで注目さ
れていたが、アルミナの固有の欠点である低靭性によ
り、その用途が限られている。2. Description of the Related Art Conventionally, alumina has been attracting attention as a high temperature resistant structural member because of its excellent environmental resistance and high temperature strength. However, its use is limited due to its low toughness which is an inherent defect of alumina. There is.
【０００３】そこで、近年では、アルミナの破壊靭性を
向上させるために、種々の複合化が試みられている。例
えば、Ａｌ2 Ｏ3 −ＳｉＣナノコンポジィット、Ａｌ2
Ｏ3−ＺｒＯ2 複合材料（例えば、特開昭６１−１２２
１６４号公報、特開昭６３−１３９０４４号公報等参
照）、および板状β−Ａｌ2 Ｏ3 の分散（例えば、特開
昭６３−１３４５５１号公報等参照）等により、純粋な
アルミナの焼結体より強度と靭性を向上することができ
る。Therefore, in recent years, various composites have been tried in order to improve the fracture toughness of alumina. For example, Al 2 O 3 —SiC nanocomposite, Al 2
O 3 -ZrO 2 composite material (see, for example, JP-A-61-122)
164, JP-A-63-139044, etc.), and plate-like β-Al 2 O 3 dispersion (see, for example, JP-A-63-134551, etc.), etc. to sinter pure alumina. Strength and toughness can be improved over the body.
【０００４】[0004]
【発明が解決しようとする問題点】しかし、上記Ａｌ2
Ｏ3 −ＳｉＣナノコンポジィットでは、Ａｌ2 Ｏ3 中に
非酸化物のＳｉＣを分散させているために、酸化雰囲気
において高温状態で使用される場合には耐酸化性に欠け
るという問題があった。[Problems to be Solved by the Invention] However, the above Al 2
The O 3 -SiC nanocomposite has a problem that it lacks oxidation resistance when used at high temperature in an oxidizing atmosphere because non-oxide SiC is dispersed in Al 2 O 3 . .
【０００５】また、Ａｌ2 Ｏ3 −ＺｒＯ2 複合材料は９
００℃付近の温度で強度が急激に低下するため高温強度
が低く、高温下において応力が作用するような状態での
使用には適しないという問題があった。Al 2 O 3 -ZrO 2 composite material is 9
Since the strength sharply decreases at a temperature near 00 ° C., the high temperature strength is low, and there is a problem that it is not suitable for use in a state where stress acts at high temperature.
【０００６】さらに、板状のβ−Ａｌ2 Ｏ3 を分散した
アルミナ焼結体では、通常の焼成温度でアルミナ母相結
晶粒子の粒成長速度がβ−Ａｌ2 Ｏ3 の粒成長速度より
大きいため、アルミナ母相の粒成長により板状β−Ａｌ
2 Ｏ3 による靱性向上の効果が大きく低減するという問
題があった。Further, in the plate-shaped β-Al 2 O 3 -dispersed alumina sintered body, the grain growth rate of the alumina matrix crystal grains is higher than that of β-Al 2 O 3 at a normal firing temperature. Therefore, due to the grain growth of the alumina matrix, plate-like β-Al
There is a problem that the effect of 2 O 3 for improving toughness is greatly reduced.
【０００７】[0007]
【問題点を解決するための手段】本発明者は、アルミナ
の組織と機械的特性の関係に対して研究を重ねた結果、
板状形状を有するアルミナ結晶が一定方向に配列した組
織を有し、さらに、特定の粒界分散相が存在することに
より、材料の室温強度、高温強度および破壊靭性が同時
に向上できることを知見し、本発明に至った。また、こ
のような板状アルミナ結晶が一定方向に配列した組織
は、一旦、アルミナ結晶の粒界に特定の粒界分散相が存
在した焼結体を作製し、この焼結体を所定の温度で一軸
加圧することにより得られることを見い出し、本発明に
至った。As a result of repeated studies on the relationship between the structure and mechanical properties of alumina, the present inventor found that
It was found that the alumina crystal having a plate-like shape has a structure in which the crystals are arranged in a certain direction, and further, due to the existence of a specific grain boundary dispersed phase, room temperature strength, high temperature strength and fracture toughness of the material can be simultaneously improved, The present invention has been completed. In addition, such a structure in which plate-like alumina crystals are arranged in a certain direction, once, a sintered body in which a specific grain boundary dispersed phase is present in the grain boundaries of the alumina crystal is prepared, and the sintered body is heated to a predetermined temperature. The inventors have found that it can be obtained by uniaxially pressurizing, and reached the present invention.
【０００８】即ち、本発明のアルミナ質焼結体は、アル
ミナ板状結晶が、その厚み方向に相互に当接して配列
し、前記アルミナ板状結晶の粒界に、周期律表第２ａ，
３ａ，４ａ族元素，ＴａおよびＭｎのうち少なくとも一
種の酸化物および／または該酸化物とＡｌ2 Ｏ3 との複
合酸化物からなる分散相が存在するものである。That is, in the alumina-based sintered body of the present invention, the alumina plate crystals are arranged in contact with each other in the thickness direction, and are arranged at the grain boundaries of the alumina plate crystals at the periodic table 2a,
There is a dispersed phase composed of an oxide of at least one of 3a and 4a group elements, Ta and Mn and / or a complex oxide of the oxide and Al 2 O 3 .
【０００９】また、本発明のアルミナ質焼結体は、アル
ミナ結晶と、これらのアルミナ結晶の粒界に周期律表第
２ａ，３ａ，４ａ族元素，ＴａおよびＭｎのうち少なく
とも一種の酸化物および／または該酸化物とＡｌ2 Ｏ3
との複合酸化物からなる分散相が存在する焼結体を、加
熱した状態で一軸圧縮応力を加えることにより得られ
る。Further, the alumina-based sintered body of the present invention has alumina crystals, and at the grain boundaries of these alumina crystals, at least one oxide of Group 2a, 3a, and 4a elements of the periodic table, Ta and Mn, and / Or the oxide and Al 2 O 3
It can be obtained by applying a uniaxial compressive stress to a sintered body in which a dispersed phase composed of a complex oxide of and is present in a heated state.
【００１０】以下、本発明を詳述する。The present invention will be described in detail below.
【００１１】本発明のアルミナ質焼結体では、図１に示
すように、アルミナ板状結晶１と、このアルミナ板状結
晶１の粒界に特定の分散相２を有するものである。そし
て、アルミナ板状結晶１は、その厚み方向ｔ（加圧方
向）に対して直角の長さ方向Ｈが相互にほぼ平行になる
ように配列している。言い換えれば、アルミナ板状結晶
１はその厚み方向に相互に当接（面接触）し、加圧方向
に積層している状態となる。このようなアルミナ板状結
晶のアスペクト比（長さＨ／厚みｔ）は１．７〜５、特
には３〜５が望ましい。As shown in FIG. 1, the alumina sintered body of the present invention has an alumina plate crystal 1 and a specific dispersed phase 2 at the grain boundary of this alumina plate crystal 1. The alumina plate crystals 1 are arranged so that their lengthwise directions H, which are perpendicular to the thickness direction t (pressurizing direction), are substantially parallel to each other. In other words, the alumina plate crystals 1 are in contact with each other in the thickness direction (surface contact) and are stacked in the pressing direction. The aspect ratio (length H / thickness t) of such an alumina plate crystal is preferably 1.7 to 5, and more preferably 3 to 5.
【００１２】また、アルミナ板状結晶の粒界に存在する
分散相は、周期律表第２ａ，３ａ，４ａ族元素，Ｔａお
よびＭｎのうち少なくとも一種の酸化物および／または
該酸化物とＡｌ2 Ｏ3 との複合酸化物であることが必要
である。即ち、分散相は、周期律表第２ａ，３ａ，４ａ
族元素，ＴａおよびＭｎの少なくとも一種の酸化物から
なる場合、周期律表第２ａ，３ａ，４ａ族元素，Ｔａお
よびＭｎのうち少なくとも一種の酸化物とＡｌ2 Ｏ3 と
の複合酸化物からなる場合、周期律表第２ａ，３ａ，４
ａ族元素，ＴａおよびＭｎのうち少なくとも一種の酸化
物および該酸化物とＡｌ2 Ｏ3 との複合酸化物からなる
場合がある。The dispersed phase existing at the grain boundary of the alumina plate crystal is an oxide of at least one of the elements of groups 2a, 3a and 4a of the periodic table, Ta and Mn and / or the oxide and Al 2 It must be a complex oxide with O 3 . That is, the dispersed phase is the periodic table 2a, 3a, 4a.
When it is composed of an oxide of at least one of the group elements Ta and Mn, it is composed of a complex oxide of at least one of the elements of groups 2a, 3a and 4a of the periodic table, Ta and Mn and Al 2 O 3. In case of periodic table 2a, 3a, 4
It may consist of an oxide of at least one of the group a elements, Ta and Mn, and a complex oxide of the oxide and Al 2 O 3 .
【００１３】周期律表第２ａ族元素としては、Ｂｅ，Ｍ
ｇ，Ｃａ，Ｓｒ，Ｂａ，Ｒａがあり、周期律表第３ａ族
元素としては、Ｓｃ，Ｙ，ランタノイド系やアクチノイ
ド系があり、周期律表第４ａ族元素としては、Ｔｉ，Ｚ
ｒ，Ｈｆがある。As elements of Group 2a of the periodic table, Be, M
g, Ca, Sr, Ba and Ra, Sc, Y, lanthanoids and actinoids are included as elements of Group 3a of the periodic table, and Ti and Z are included as elements of Group 4a of the periodic table.
There are r and Hf.
【００１４】本発明においては、Ｍｇおよび周期律表第
３ａ、４ａ族元素の少なくとも一種の酸化物からなる分
散相や、Ｍｇおよび周期律表第３ａ、４ａ族元素の少な
くとも一種の酸化物とＡｌ2 Ｏ3 との複合酸化物からな
る分散相や、前述した酸化物からなる分散相と複合酸化
物からなる分散相が混在する場合が、焼結体の組織制御
の効果が大きく好ましい。分散相としては、ＭｇＡｌ2
Ｏ4 ，ＢａＡｌ12Ｏ19，ＺｒＯ2 ，Ａｌ2 ＴｉＯ5 ，Ｙ
3 Ａｌ5 Ｏ12，Ｔａ2 Ｏ5 ，ＭｎＡｌ2 Ｏ4 が望まし
い。In the present invention, a dispersed phase composed of Mg and at least one oxide of elements of Groups 3a and 4a of the Periodic Table, and at least one oxide of Mg and elements of Groups 3a and 4a of the Periodic Table and Al. It is preferable that the dispersed phase composed of a composite oxide of 2 O 3 and the dispersed phase composed of the aforementioned oxide and the dispersed phase composed of a composite oxide are mixed, because the effect of controlling the structure of the sintered body is large. As the dispersed phase, MgAl 2
O 4 , BaAl 12 O 19 , ZrO 2 , Al 2 TiO 5 , Y
3 Al 5 O 12, Ta 2 O 5, MnAl 2 O 4 is preferred.
【００１５】このような分散相は全量中５〜２５体積％
含有することが望ましい。これは、５体積％よりも分散
相が少ない場合には、アルミナ板状結晶の粒界の安定性
が低く、高温で粒成長を発生し易くなり、分散相が２５
体積％よりも多くなると、アルミナ板状結晶の配向組織
の形成を阻害し、材料の特性を低下させる傾向があるか
らである。分散相の平均結晶粒径は３μｍ以下が望まし
い。Such a dispersed phase is 5 to 25% by volume in the total amount.
It is desirable to contain. This is because when the dispersed phase is less than 5% by volume, the stability of the grain boundaries of the alumina plate crystal is low, and grain growth is likely to occur at a high temperature.
This is because when the content is more than the volume%, the formation of the oriented structure of the alumina plate crystal is obstructed and the material properties tend to be deteriorated. The average crystal grain size of the dispersed phase is preferably 3 μm or less.
【００１６】次に、本発明のアルミナ質焼結体の製法に
ついて述べる。本発明のアルミナ質焼結体は、先ず公知
の原料、例えば、Ａｌと周期律表第２ａ，３ａ，４ａ族
元素，ＴａおよびＭｎの少なくとも一種の金属粉末、ま
たはこれらの酸化物粉末、当該金属を含む有機、無機物
あるいはその溶液を用い、所定の組成に調合、混合後、
所望の成型手段、例えば、金型プレス，鋳込み成型，押
出成型，射出成型，冷間静水圧プレスなどにより任意の
形状に成形する。この成形体を公知の焼結法、例えば、
ホットプレス法，常圧焼成法，ガス加圧焼成法により焼
成することにより得られる。さらに、焼結後に熱間静水
圧処理（ＨＩＰ）処理、およびガラスシール後ＨＩＰ処
理しても良く、この場合には、対理論密度比９５％以上
の緻密な焼結体を得ることができる。Next, a method for producing the alumina-based sintered body of the present invention will be described. The alumina-based sintered body of the present invention comprises a known raw material, for example, Al and at least one metal powder of elements 2a, 3a, 4a of the periodic table, Ta and Mn, or an oxide powder thereof, or the metal. Using an organic or inorganic substance or solution containing, after preparing and mixing to a predetermined composition,
It is molded into a desired shape by a desired molding means, for example, a die press, a casting molding, an extrusion molding, an injection molding, a cold isostatic pressing and the like. This molded body is subjected to a known sintering method, for example,
It is obtained by firing by a hot press method, a normal pressure firing method, or a gas pressure firing method. Furthermore, hot isostatic pressing (HIP) treatment may be performed after sintering, and HIP treatment may be performed after glass sealing. In this case, a dense sintered body having a theoretical density ratio of 95% or more can be obtained.
【００１７】そして、本発明の製法では、上記アルミナ
板状結晶と分散相からなる焼結体を加熱した状態で一軸
圧縮応力を加えて変形させることが重要である。このよ
うな加熱状態での加圧処理により、アルミナ結晶が板状
に塑性変形すると同時に、アルミナ板状結晶の長さ方向
Ｈが互いに平行となるように配列した組織を形成するこ
とができる。In the manufacturing method of the present invention, it is important to apply uniaxial compressive stress to deform the sintered body composed of the alumina plate crystals and the dispersed phase while being heated. By the pressure treatment in such a heated state, the alumina crystals are plastically deformed into a plate shape, and at the same time, a structure can be formed in which the length directions H of the alumina plate crystals are arranged to be parallel to each other.
【００１８】加圧処理する以前の焼結体のアルミナの平
均結晶粒径は５μｍ以下が望ましい。これは、５μｍよ
りも大きくなると、大きなアスペクト比を有する板状結
晶を形成し難くなるからである。加圧処理する以前の焼
結体のアルミナの平均結晶粒径は３μｍ以下が特に望ま
しい。The average crystal grain size of alumina in the sintered body before pressure treatment is preferably 5 μm or less. This is because if it exceeds 5 μm, it becomes difficult to form a plate crystal having a large aspect ratio. It is particularly desirable that the average crystal grain size of alumina in the sintered body before pressure treatment is 3 μm or less.
【００１９】また、一軸圧縮応力を加える際の加熱処理
条件については、１１００℃以下では、結晶の変形抵抗
が大きく、材料が脆性的な破壊が発生し易い。また１６
００℃以上の温度では、動的再結晶や、粒界軟化により
異方性結晶（アルミナ板状結晶）の形成と配列が困難と
なる。従って、加熱処理条件の好ましい温度範囲は１１
００〜１６００℃、特に１１５０〜１５００℃が望まし
い。Regarding the heat treatment conditions for applying the uniaxial compressive stress, when the temperature is 1100 ° C. or less, the deformation resistance of the crystal is large and the material is liable to be brittle. Again 16
At a temperature of 00 ° C. or higher, dynamic recrystallization and grain boundary softening make it difficult to form and arrange anisotropic crystals (alumina plate crystals). Therefore, the preferable temperature range of the heat treatment condition is 11
00 to 1600 ° C, particularly 1150 to 1500 ° C is desirable.
【００２０】さらに、上記焼結体を加圧により変形させ
る時の平均歪速度は１×１０-5〜１×１０-3／ｓの範囲
が好適である。歪速度が１×１０-3／ｓより高いと、変
形抵抗が大幅に増加するだけでなく、材料中に多くの欠
陥が生成する傾向にあるからである。また、歪速度が１
×１０-5より低ければ、変形中での拡散により変形した
結晶が等軸結晶に回復する傾向にあるからである。ま
た、本発明の組織を形成するためには、加圧処理におけ
る最終的な歪みを、０．１０以上、特には０．３以上と
することが望ましい。Further, the average strain rate when deforming the sintered body by pressurization is preferably in the range of 1 × 10 -5 to 1 × 10 -3 / s. This is because if the strain rate is higher than 1 × 10 −3 / s, not only the deformation resistance increases significantly, but also many defects tend to be generated in the material. Also, the strain rate is 1
This is because if it is lower than × 10 −5 , the deformed crystal tends to recover to an equiaxed crystal due to diffusion during deformation. Further, in order to form the texture of the present invention, it is desirable that the final strain in the pressure treatment is 0.10 or more, particularly 0.3 or more.
【００２１】[0021]
【作用】本発明のアルミナ質焼結体では、アルミナの板
状結晶が、その厚さ方向に相互に当接して配列している
ため、アルミナ板状結晶の長さ方向に平行な（アルミナ
板状結晶の厚み方向と直角方向）引張応力が作用した場
合における強度が大幅に向上し、さらに焼結体自体の靱
性を著しく向上できる。これにより、特に荷重が平面応
力である部材に好適に用いることができる。In the alumina-based sintered body of the present invention, since the plate crystals of alumina are arranged in contact with each other in the thickness direction, they are parallel to the length direction of the alumina plate crystals (alumina plate). The strength when a tensile stress acts on the crystal is significantly improved, and the toughness of the sintered body itself can be significantly improved. Accordingly, it can be suitably used especially for a member whose load is a plane stress.
【００２２】また、アルミナの板状結晶の粒界に、周期
律２ａ，３ａ，４ａ族金属，ＴａおよびＭｎの酸化物お
よび／または該酸化物とＡｌ2 Ｏ3 との複合酸化物から
なる化合物の分散相が存在しているため、アルミナ板状
結晶の異常粒成長を抑制でき、板状結晶形状を安定した
状態で存在させることができる。これらの元素の酸化物
は高温でも安定性が高く、周期律２ａ，３ａ，４ａ族金
属，ＴａおよびＭｎの酸化物やこれらの金属が互いに複
合酸化物を形成し、もしくはこれらの周期律２ａ，３
ａ，４ａ族金属，ＴａおよびＭｎとアルミナとにより安
定な複合酸化物を形成し、アルミナ板状結晶の粒界を安
定させ、結晶の異方性を保持し、アルミナ質焼結体の強
度を向上する。Further, at the grain boundary of the plate-like crystal of alumina, a compound consisting of an oxide of metals of the periodic groups 2a, 3a, 4a, Ta and Mn and / or a complex oxide of the oxide and Al 2 O 3 . Due to the existence of the dispersed phase of, the abnormal grain growth of the alumina plate crystal can be suppressed, and the plate crystal shape can exist in a stable state. Oxides of these elements are highly stable even at high temperatures, and oxides of the periodic metals 2a, 3a, 4a, Ta and Mn and these metals form complex oxides with each other, or these periodic metals 2a, Three
Forming a stable composite oxide with a, 4a group metals, Ta and Mn and alumina, stabilizing the grain boundary of the alumina plate crystal, maintaining the crystal anisotropy, and improving the strength of the alumina sintered body. improves.
【００２３】よって、本発明のアルミナ質焼結体では、
安定性が高いアルミナ板状結晶が一定方向で配列し、こ
れらの粒界に所定の分散相が存在する組織となり、室温
から高温まで優れた強度と破壊靭性を有する構造材料を
提供できる。Therefore, in the alumina-based sintered body of the present invention,
It is possible to provide a structural material in which highly stable alumina plate crystals are arranged in a certain direction and a predetermined dispersed phase exists in these grain boundaries, and which has excellent strength and fracture toughness from room temperature to high temperature.
【００２４】[0024]
【実施例】アルミナ原料粉末と周期律２ａ，３ａ，４ａ
族金属，ＴａおよびＭｎの酸化物原料粉末を出発原料と
し、焼結体組成が、表１に示すような組成となるように
秤量し、これらの混合粉末を１ｔｏｎ／ｃｍ2 の圧力で
プレス成形した後、３ｔｏｎ／ｃｍ2 の圧力で静水圧成
形を行った。[Examples] Alumina raw material powder and periodicity 2a, 3a, 4a
Starting powders of oxide raw materials of group metals, Ta and Mn are weighed so that the composition of the sintered body is as shown in Table 1, and these mixed powders are press-molded at a pressure of 1 ton / cm 2. After that, hydrostatic molding was performed at a pressure of 3 ton / cm 2 .
【００２５】これらの成形体を大気中において１６５０
℃で５時間常圧焼成した。焼結体中の分散相の種類と存
在量およびアルミナ粒子の平均結晶粒径を表１に示す。These molded bodies were subjected to 1650 in the atmosphere.
It was baked at atmospheric pressure for 5 hours at atmospheric pressure. Table 1 shows the types and abundances of the dispersed phase in the sintered body and the average crystal grain size of the alumina particles.
【００２６】そして、上記の焼結体を表１に示すような
温度で加熱し、表１に示すような平均歪速度となるよう
に一軸圧縮応力を加え、最終的に表１に示すような歪を
焼結体に生じさせた。Then, the above-mentioned sintered body is heated at a temperature as shown in Table 1, uniaxial compressive stress is applied so as to obtain an average strain rate as shown in Table 1, and finally as shown in Table 1. Strain was created in the sintered body.
【００２７】[0027]
【表１】 [Table 1]
【００２８】加圧処理後の焼結体組織を光学顕微鏡によ
り観察したところ、本発明の焼結体のアルミナ結晶粒が
板状になっていることを確認した。このアルミナ板状結
晶の平均アスペクト比を表２に示す。尚、アルミナ板状
結晶のアスペクト比とは、図１に示すように、焼結体の
一断面において、アルミナ板状結晶の長さＨと厚みｔと
の比（長さＨ／厚みｔ）とした。When the structure of the sintered body after pressure treatment was observed with an optical microscope, it was confirmed that the alumina crystal grains of the sintered body of the present invention had a plate shape. Table 2 shows the average aspect ratio of this alumina plate crystal. The aspect ratio of the alumina plate crystal is, as shown in FIG. 1, the ratio of the length H to the thickness t of the alumina plate crystal in one cross section of the sintered body (length H / thickness t). did.
【００２９】さらに、これらの焼結体をＪＩＳ−Ｒ１６
０１にて指定されている形状まで研磨し抗折試料を作製
した。この試料についてＪＩＳ−Ｒ１６０１に基づく室
温および１４００℃での４点曲げ抗折強度試験を実施し
た。また、ビッカース圧痕法により破壊靭性（ＫIC）を
測定した。これらの結果を表２に示した。Further, these sintered bodies were made into JIS-R16.
The sample was manufactured by polishing to a shape designated by 01. This sample was subjected to a 4-point bending bending strength test at room temperature and 1400 ° C. based on JIS-R1601. The fracture toughness (K IC ) was also measured by the Vickers indentation method. Table 2 shows the results.
【００３０】[0030]
【表２】 [Table 2]
【００３１】表１、２の結果から、本発明に基づいて得
られた、板状配列組織を有する焼結体は、従来のアルミ
ナ材料およびアルミナ基複合材料に比べて、優れた室温
と高温強度および破壊靭性を示すことが判る。From the results shown in Tables 1 and 2, the sintered body having a plate-like array structure obtained according to the present invention has excellent room temperature and high temperature strength as compared with conventional alumina materials and alumina-based composite materials. It can be seen that the material exhibits fracture toughness.
【００３２】即ち、本発明のアルミナ質焼結体では、室
温での曲げ強度が６５０ＭＰａ以上であり、１４００℃
での曲げ強度が３６０ＭＰａ以上であり、さらに靱性が
４．０ＭＰａ・ｍ1/2 以上と優れた特性を示す。特に、
試料Ｎo.１〜９については、室温での曲げ強度が７００
ＭＰａ以上であり、１４００℃での曲げ強度が３９０Ｍ
Ｐａ以上であり、さらに靱性が４．８ＭＰａ・ｍ1/2 以
上の優れた特性を有する。That is, in the alumina-based sintered body of the present invention, the bending strength at room temperature is 650 MPa or more, and 1400 ° C.
Flexural strength at 360 MPa or more and toughness of 4.0 MPa · m 1/2 or more, which are excellent characteristics. In particular,
Sample Nos. 1 to 9 have bending strength of 700 at room temperature.
MPa or more, bending strength at 1400 ° C is 390M
It has excellent characteristics of Pa or more and toughness of 4.8 MPa · m 1/2 or more.
【００３３】一方、試料Ｎo.１５は従来のアルミナ焼結
体であり、分散相が存在しない場合である。この場合に
は、室温や高温での曲げ強度が低く、また靱性も低い。
さらに、試料Ｎo.１６は、従来のアルミナ−ジルコニア
系の焼結体であり、加圧処理をせず、アルミナが板状結
晶となっていない場合である。この場合には、室温での
曲げ強度は高いが高温強度が極端に低くなることが判
る。On the other hand, sample No. 15 is a conventional alumina sintered body, and there is no dispersed phase. In this case, the bending strength at room temperature or high temperature is low, and the toughness is also low.
Further, Sample No. 16 is a conventional alumina-zirconia-based sintered body, which is a case where the pressure treatment is not performed and alumina is not a plate crystal. In this case, the bending strength at room temperature is high, but the high temperature strength is extremely low.
【００３４】[0034]
【発明の効果】本発明のアルミナ質焼結体では、アルミ
ナの板状結晶が、その厚み方向に相互に当接して配列
し、アルミナ板状結晶の粒界に、周期律２ａ，３ａ，４
ａ族金属，ＴａおよびＭｎの酸化物および／または該酸
化物とＡｌ2 Ｏ3 との複合酸化物からなる化合物の分散
相が存在しているため、アルミナ板状結晶の長さ方向に
平行な引張応力が作用した場合における強度が大幅に向
上し、さらに焼結体自体の靱性を著しく向上でき、ま
た、周期律２ａ，３ａ，４ａ族金属，ＴａおよびＭｎか
らなる酸化物や、これらの酸化物とＡｌ2 Ｏ3 との複合
酸化物からなる分散相により、アルミナ板状結晶の異常
粒成長を抑制でき、板状結晶形状を安定した状態で存在
させることができる。これにより、室温から高温まで優
れた強度と破壊靭性を有するアルミナ質焼結体を提供で
きる。In the alumina-based sintered body of the present invention, the plate-like crystals of alumina are arranged in contact with each other in the thickness direction, and are arranged at the grain boundaries of the alumina plate-like crystals at the periodic intervals 2a, 3a, 4
Since the dispersed phase of the group a metal, the oxide of Ta and Mn and / or the compound consisting of the complex oxide of the oxide and Al 2 O 3 exists, it is parallel to the length direction of the alumina plate crystal. The strength when tensile stress acts is significantly improved, the toughness of the sintered body itself can be significantly improved, and the oxides of the periodic metals 2a, 3a, 4a, Ta and Mn, and the oxides of these metals are used. By the dispersed phase composed of a complex oxide of a substance and Al 2 O 3 , abnormal grain growth of alumina plate crystals can be suppressed, and the plate crystal shape can exist in a stable state. This makes it possible to provide an alumina sintered body having excellent strength and fracture toughness from room temperature to high temperature.
【図１】本発明のアルミナ質焼結体の縦断面図である。FIG. 1 is a vertical cross-sectional view of an alumina-based sintered body of the present invention.
１・・・アルミナ板状結晶 ２・・・分散相 1 ... Alumina plate crystal 2 ... Dispersed phase
Claims (2)
に当接して配列し、前記アルミナ板状結晶の粒界に、周
期律表第２ａ，３ａ，４ａ族元素，ＴａおよびＭｎのう
ち少なくとも一種の酸化物および／または該酸化物とＡ
ｌ2 Ｏ3 との複合酸化物からなる分散相が存在すること
を特徴とするアルミナ質焼結体。1. Alumina plate crystals are arranged so as to be in contact with each other in the thickness direction, and at the grain boundaries of the alumina plate crystals, among the elements of groups 2a, 3a, 4a of the periodic table, Ta and Mn. At least one oxide and / or the oxide and A
An alumina-based sintered body, characterized in that a dispersed phase consisting of a complex oxide with l 2 O 3 is present.
粒界に周期律表第２ａ，３ａ，４ａ族元素，Ｔａおよび
Ｍｎのうち少なくとも一種の酸化物および／または該酸
化物とＡｌ2 Ｏ3 との複合酸化物からなる分散相が存在
する焼結体を、加熱した状態で一軸圧縮応力を加えるこ
とを特徴とするアルミナ質焼結体の製造方法。2. An alumina crystal, and an oxide of at least one of the elements of groups 2a, 3a and 4a of the periodic table, Ta and Mn and / or the oxide and Al 2 O 3 at the grain boundaries of these alumina crystals. A method for producing an alumina-based sintered body, which comprises applying a uniaxial compressive stress in a heated state to a sintered body having a dispersed phase composed of a complex oxide of
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31505194A JP3359443B2 (en) | 1994-12-19 | 1994-12-19 | Alumina sintered body and method for producing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31505194A JP3359443B2 (en) | 1994-12-19 | 1994-12-19 | Alumina sintered body and method for producing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08169752A true JPH08169752A (en) | 1996-07-02 |
| JP3359443B2 JP3359443B2 (en) | 2002-12-24 |
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ID=18060849
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP31505194A Expired - Fee Related JP3359443B2 (en) | 1994-12-19 | 1994-12-19 | Alumina sintered body and method for producing the same |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001155546A (en) * | 1999-11-29 | 2001-06-08 | Ngk Spark Plug Co Ltd | Insulator for spark plug and spark plug having the same |
-
1994
- 1994-12-19 JP JP31505194A patent/JP3359443B2/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001155546A (en) * | 1999-11-29 | 2001-06-08 | Ngk Spark Plug Co Ltd | Insulator for spark plug and spark plug having the same |
| JP4530380B2 (en) * | 1999-11-29 | 2010-08-25 | 日本特殊陶業株式会社 | Spark plug insulator and spark plug including the same |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3359443B2 (en) | 2002-12-24 |
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