JP3888714B2 - Alumina sintered body - Google Patents
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- JP3888714B2 JP3888714B2 JP28899796A JP28899796A JP3888714B2 JP 3888714 B2 JP3888714 B2 JP 3888714B2 JP 28899796 A JP28899796 A JP 28899796A JP 28899796 A JP28899796 A JP 28899796A JP 3888714 B2 JP3888714 B2 JP 3888714B2
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- sintered body
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Description
【０００１】
【発明の属する技術分野】
本発明は、電気的特性に優れたアルミナ質焼結体に関し、特に高周波領域での誘電損失が小さいアルミナ質焼結体に関する。
【０００２】
【従来の技術】
アルミナ質焼結体は、耐熱性、耐薬品性、耐プラズマ性に優れ、さらに高周波領域での誘電損失（ｔａｎδ）が小さいことから、半導体用高周波プラズマ装置などに使われる絶縁材料や高周波透過用の窓材として用いられている。
【０００３】
【発明が解決しようとする課題】
しかしながら、この焼結体中に不純物としてＮａやＫなどのアルカリ金属を１００ｐｐｍ以上含むと誘電損失が著しく上昇し、その誘電損失が上がることにより、高周波の透過率が悪化するなどの効率の低下や、あるいは部品の発熱が高くなり部品が破損し易くなるなどの不具合を引き起こしてしまう。
【０００４】
このアルカリ金属が多く含まれる状況としては、元々の原料に含まれている場合と、粉砕、成形、成形体加工、焼成などの製造プロセス中に混入する場合とが考えられ、これを回避するためには、アルカリ金属の含有量が１００ｐｐｍより少ない低アルカリの高純度原料を用い、かつ製造工程を厳重に管理してアルカリ金属の混入を防ぐ必要があった。そのため、低アルカリの焼結体、言い換えれば低誘電損失のアルミナ質焼結体を得るには大幅なコスト上昇を招くという問題があった。
【０００５】
本発明は、上述した従来のアルミナ質焼結体が有する課題に鑑みなされたものであって、その目的は、アルカリ金属を１００ｐｐｍ以上含んでも誘電損失が小さいアルミナ質焼結体を提供することにある。
【０００６】
【課題を解決するための手段】
本発明者等は、上記目的を達成するため鋭意研究した結果、アルミナ質焼結体中にコーディエライト相（２ＭｇＯ・２Ａｌ2Ｏ3・５ＳｉＯ2）を共存させれば、アルカリ金属を１００ｐｐｍ以上含んでも誘電損失を小さく抑えられるとの知見を得て本発明を完成した。
【０００７】
即ち本発明は、アルカリ金属を８００〜２１００ｐｐｍとＡｌ2 Ｏ3 を９８ｗｔ％以上含み、成形体を１５００℃以上の温度で焼結して得られるアルミナ質焼結体において、その焼結体中にＳｉＯ2 とＭｇＯを合計量で０．２〜１．０ｗｔ％、重量比（ＳｉＯ2 ／ＭｇＯ）で２〜４含み、そのＳｉＯ2 とＭｇＯから生成されるコーディエライト相を０．３〜１．４ｗｔ％含む焼結体とし、かつ１００ｋＨｚ〜１ＧＨｚでの誘電損失が０．００４を越えない焼結体とすることを特徴とするアルミナ質焼結体であることを要旨とする。
以下にさらに詳細に述べる。
【０００８】
前述したようにアルミナ質焼結体中にコーディエライト相を共存させることととした。このコーディエライト相をアルミナ中に存在させることで、アルカリ金属を１００ｐｐｍ以上含んでも誘電損失の上昇が認められない。これは、ＳｉＯ2とＭｇＯを含むアルミナ原料から成る成形体を焼成すると、まずコーディエライトに近い組成の液相が粒界に生成し、その液相から冷却に伴いコーディエライト相が析出するが、その析出する過程で生じた結晶の結晶構造中に存在する空孔にアルカリ金属イオンが捕獲されるため、アルカリ金属イオンの移動が抑えられ、誘電損失が上がらないものと考えられる。
【０００９】
そのコーディエライト相の含有量としては、０．３〜１．４ｗｔ％（内割り、以下同じ）とした。コーディエライト相が０．３ｗｔ％より少ないと効果が認められず、１．４ｗｔ％より多いと逆に誘電損失の高い（ｔａｎδ＝０．１）コーディエライト相が多くなるので、誘電損失が大きくなり好ましくない。
【００１０】
上記コーディエライト相を生成させるＳｉＯ2とＭｇＯの含有量としては、合計量で０．２〜１．０ｗｔ％、重量比（ＳｉＯ2／ＭｇＯ）で２〜４となる量とした。合計量が０．２ｗｔ％より少ないとコーディエライト相の生成が０．３ｗｔ％より少なくなり、１．０ｗｔ％より多いとコーディエライト相の生成が１．４ｗｔ％より多くなる。また、比が２より小さいとフリーのＭｇＯが多くなり誘電損失が大きくなる。逆に４より大きいとＳｉＯ2成分が多くなり緻密化を妨げ好ましくない。以上のような組成を有する焼結体であれば、低アルカリでなくても誘電損失が０．００４を越えないアルミナ質焼結体とすることができる。
【００１１】
【発明の実施の形態】
上記アルミナ質焼結体の製造方法を述べると、先ずアルミナ粉末には、純度が９９％以上でＳｉ、Ｍｇ、アルカリ金属以外の金属が酸化物換算で５００ｐｐｍ以下の高純度のアルミナ粉末を原料として用意する。これ以上の不純物を含むと焼結性を悪化する、あるいは焼結体の絶縁抵抗や誘電率などの電気的特性を下げるため好ましくない。
【００１２】
用意したアルミナ原料にＳｉＯ2及びＭｇＯ原料を前述の範囲内の量だけ添加する。ＳｉＯ2及びＭｇＯの原料としては、純度９９％以上のものが望ましく、その細かさとしては均一に混合し易い１μｍ以下の平均粒径を有するものが望ましい。ただし、ＭｇＯについては、水系で湿式混合する場合、硝酸マグネシウム（Ｍｇ（ＮＯ2）3・６Ｈ2Ｏ）を水溶液として混合してもよい。そのほかのＳｉＯ2、ＭｇＯの原料としては、高純度の粘土質原料、例えば純度９９、８％以上のカオリンなども用いることができる。これらＳｉＯ2、ＭｇＯ原料中のアルカリ金属の含有量としては、０．２ｗｔ％以下が望ましく、市販されている純度の高い原料であればほとんどが使用できる。
【００１３】
これらを配合した原料に水を加えスラリーとし、ボールミルなどで混合する。成形体の作製は、得られたスラリーにバインダーを加え、噴霧乾燥して得た顆粒をプレス成形する方法、スラリーにバインダーを加え、石膏型を用いて鋳込み成形する方法、スラリーを乾燥した後、バインダーを加えて射出成形する方法など、慣用の方法で作製することができる。
【００１４】
得られた成形体を１５００℃以上の温度で焼結する。これ以下の温度では、緻密化しないため望ましくない。焼結する炉は、アルカリ金属を多く含んだ炉材からなり、アルカリ金属成分が多く揮発するような炉であっても構わない。
【００１５】
以上の組成となるように配合し、上記の方法で製造すれば、高アルカリの原料を用いても、あるいは製造プロセス中にアルカリ金属が混入してきても誘電損失が小さいアルミナ質焼結体を得ることができる。
【００１６】
【実施例】
以下、本発明の実施例を比較例と共に挙げ、本発明をより詳細に説明する。
【００１７】
（実施例１〜４）
（１）アルミナ質焼結体の作製
市販の低アルカリ高純度アルミナ粉末（ＳｉＯ2：０．０２ｗｔ％、ＭｇＯ：０．０２ｗｔ％、Ｎａ2Ｏ：０．００１ｗｔ％、Ｋ2Ｏ：０．００１ｗｔ％）に、ＳｉＯ2源としてアエロジル（アエロジル１３０：ＳｉＯ2純度９９％）、ＭｇＯ源として硝酸マグネシウムを表１に示す含有量になるように加え、それに水及び分散剤を加えて樹脂ボールを媒体としたボールミルにより混合した。得られたスラリーにバインダーとしてＰＶＡを添加し噴霧乾燥して顆粒を得た。得られた顆粒をＣＩＰ成形し、その成形体をアルカリ金属の成分を多く含む断熱材を使用している炉で表１に示す温度で焼結して焼結体を作製した。
【００１８】
（２）評価
得られた焼結体を粉砕し、化学分析でＳｉＯ2、ＭｇＯ、Ｎａ、Ｋを定量し、ＳｉＯ2とＭｇＯの合計量と重量比を求めた。また、ＸＲＤでコーディエライト相の含有量を求めた。さらに、焼結体の嵩比重をアルキメデス法で求め、相対密度を求めた。さらにまた、焼結体の誘電損失を電流電圧法で求めた。それらの結果を表１に示す。
【００１９】
（実施例５〜７）
（１）アルミナ質焼結体の作製
市販の高純度アルミナ粉末（ＳｉＯ2：０．０３ｗｔ％、ＭｇＯ：０．０１ｗｔ％、Ｎａ2Ｏ：０．０５ｗｔ％、Ｋ2Ｏ：０．０４ｗｔ％）に、実施例１と同じＳｉＯ2源とＭｇＯ源を表１に示す含有量になるように加え、実施例１と同様に混合、成形し、その成形体を空焼きしてアルカリ金属を充分揮発させた炉で表１に示す温度で焼結して焼結体を作製した。
【００２０】
（２）評価
以下の実施例も含め実施例１と同様に評価した。それらの結果を表１に示す。
【００２１】
（実施例８）
（１）アルミナ質焼結体の作製
実施例５と同じアルミナ粉末に、ＳｉＯ2源として高純度カオリン（ＳｉＯ2：４５．７ｗｔ％、Ａｌ2Ｏ3：３８．０ｗｔ％、ＭｇＯ：０．０６ｗｔ％、Ｎａ2Ｏ：０．０７ｗｔ％、Ｋ2Ｏ：０．１３ｗｔ％、強熱減量：１４．６ｗｔ％）、ＭｇＯ源として硝酸マグネシウムを表１に示す含有量になるように加え、実施例１と同様に混合、成形し、その成形体を実施例５と同じ炉で表１に示す温度で焼結して焼結体を作製した。
【００２２】
（実施例９）
（１）アルミナ質焼結体の作製
実施例５と同じアルミナ粉末、ＳｉＯ2源、ＭｇＯ源を用いて表１に示す含有量になるように配合し、それを実施例５と同様に混合、成形し、その成形体を実施例１と同じ炉で表１に示す温度で焼結して焼結体を作製した。
【００２３】
（比較例１〜８）比較のために比較例１では、ＳｉＯ2、ＭｇＯ源を加えない他は実施例５と同様に、比較例２〜５では、ＳｉＯ2、ＭｇＯ源を本発明の範囲外の量を添加した他は実施例１と同様に、比較例６では、成形体の焼結温度を本発明の範囲外とした他は実施例１と同様に、比較例７では、ＭｇＯ源を加えない他は実施例８と同様に、比較例８では、焼結に実施例５と同じ炉を用いる他は実施例１と同様にして焼結体を作製し、評価した。それらの結果も表１に示す。
【００２４】
【表１】
表１から明らかなように、実施例のアルミナ質焼結体はいずれもアルカリ金属の含有量が８００〜２１００ｐｐｍ（０．０８〜０．２１ｗｔ％）と１００ｐｐｍ（０．０１ｗｔ％）をはるかに超えているものの、本発明の範囲内の組成を有する緻密なアルミナ質焼結体であるので、いずれも誘電損失は０．００４以下であった。
【００２６】
これに対して比較例１では、ＳｉＯ2、ＭｇＯを加えずコーディエライト相がほとんど存在しないので、比較例２では、ＳｉＯ2／ＭｇＯが２より低くフリーのＭｇＯが多くなるので、比較例４では、ＳｉＯ2、ＭｇＯを加えてもその量が少なくコーディエライト相が少ないので、比較例５では、ＳｉＯ2、ＭｇＯの量が多くコーディエライト相が多すぎるので、誘電損失はいずれも実施例より１桁大きい値であった。また、比較例３では、ＳｉＯ2が多すぎるので、比較例６では、焼結温度が低すぎるので、比較例７ではコーディエライト相がほとんど存在しないのとＳｉＯ2が多すぎるので、いずれも焼結不足でやはり誘電損失が大きかった。
なお、比較例８は、実施例と同様の小さい誘電損失を有する焼結体となっているが、これは、低アルカリの高純度のアルミナ粉末（単価が低アルカリでないアルミナ粉末より１０倍程度高い）を用い、かつアルカリ金属の揮発の少ない炉を用いてアルカリ金属の含有量が１００ｐｐｍより少ない焼結体としたものであり、低アルカリでないアルミナ粉末を用い、アルカリ金属の成分を多く含む断熱材を使用している炉を用いて作製した実施例９に比べ、コストが大幅にアップした。
【００２７】
【発明の効果】
以上の通り、本発明にかかるアルミナ質焼結体であれば、アルカリ金属の含有量が１００ｐｐｍを大きく超えても１００ｋＨｚ〜１ＧＨｚにおける誘電損失が０．００４以下のアルミナ質焼結体とすることができた。これにより、コストがあまりアップしないで低誘電損失を有するアルミナ質焼結体が得られるようになった。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an alumina sintered body having excellent electrical characteristics, and more particularly to an alumina sintered body having a low dielectric loss in a high frequency region.
[0002]
[Prior art]
Alumina sintered body is excellent in heat resistance, chemical resistance, and plasma resistance, and has low dielectric loss (tan δ) in the high frequency region, so it can be used for insulating materials and high frequency transmission for high frequency plasma equipment for semiconductors. It is used as a window material.
[0003]
[Problems to be solved by the invention]
However, if the sintered body contains alkali metals such as Na and K as impurities in an amount of 100 ppm or more, the dielectric loss is remarkably increased, and the increase in the dielectric loss causes a decrease in efficiency such as deterioration of high-frequency transmittance. Or, the heat generation of the component is increased, and the component is liable to be damaged.
[0004]
In order to avoid this situation, the alkali metal may be contained in a large amount when it is contained in the original raw material and when it is mixed in a manufacturing process such as pulverization, molding, molding processing, and firing. Therefore, it was necessary to use a low-alkaline high-purity raw material having an alkali metal content of less than 100 ppm and to strictly control the production process to prevent alkali metal contamination. Therefore, there has been a problem in that a large cost is required to obtain a low alkali sintered body, in other words, an alumina sintered body having a low dielectric loss.
[0005]
The present invention has been made in view of the problems of the above-described conventional alumina sintered body, and an object thereof is to provide an alumina sintered body having a low dielectric loss even if it contains 100 ppm or more of an alkali metal. is there.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the present inventors have found that if a cordierite phase (2MgO.2Al 2 O 3 .5SiO 2 ) coexists in the alumina sintered body, the alkali metal is 100 ppm or more. The present invention was completed by obtaining the knowledge that the dielectric loss can be suppressed even if it is included.
[0007]
That is, the present invention is an alkali metal 98 wt% or more viewing contains a 800~2100ppm and Al 2 O 3 and, in an alumina sintered body obtained by sintering the molded body at 1500 ° C. or higher, the sintered body SiO 2 and MgO in a total amount of 0.2 to 1.0 wt%, 2 to 4 by weight ratio (SiO 2 / MgO), and cordierite phase generated from the SiO 2 and MgO is 0.3 to The gist of the present invention is an alumina sintered body characterized in that the sintered body contains 1.4 wt%, and the dielectric loss at 100 kHz to 1 GHz does not exceed 0.004.
More details are given below.
[0008]
As described above, the cordierite phase is allowed to coexist in the alumina sintered body. When this cordierite phase is present in alumina, no increase in dielectric loss is observed even when alkali metal is contained in an amount of 100 ppm or more. This is because when a compact made of an alumina raw material containing SiO 2 and MgO is fired, a liquid phase having a composition close to cordierite is first generated at the grain boundary, and a cordierite phase is precipitated from the liquid phase upon cooling. However, since alkali metal ions are trapped in the vacancies in the crystal structure of the crystals generated in the process of precipitation, it is considered that the movement of alkali metal ions is suppressed and the dielectric loss does not increase.
[0009]
The cordierite phase content was 0.3 to 1.4 wt% (internally divided, hereinafter the same). If the cordierite phase is less than 0.3 wt%, no effect is observed. If the cordierite phase is more than 1.4 wt%, the cordierite phase has a high dielectric loss (tan δ = 0.1) and the dielectric loss increases. It becomes large and is not preferable.
[0010]
The contents of SiO 2 and MgO for generating the cordierite phase were 0.2 to 1.0 wt% in total amount and 2 to 4 in weight ratio (SiO 2 / MgO). When the total amount is less than 0.2 wt%, the generation of cordierite phase is less than 0.3 wt%, and when it exceeds 1.0 wt%, the generation of cordierite phase is more than 1.4 wt%. On the other hand, when the ratio is smaller than 2, free MgO increases and dielectric loss increases. On the other hand, if it is larger than 4, the SiO 2 component is increased, and densification is hindered. If it is a sintered body having the above composition, it can be an alumina sintered body whose dielectric loss does not exceed 0.004 even if it is not low alkali.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The production method of the above-mentioned alumina sintered body will be described. First, the alumina powder is made from high-purity alumina powder having a purity of 99% or more and metals other than Si, Mg and alkali metals in terms of oxides of 500 ppm or less. prepare. Containing more impurities than this is not preferable because it deteriorates sinterability or lowers electrical characteristics such as insulation resistance and dielectric constant of the sintered body.
[0012]
To the prepared alumina raw material, SiO 2 and MgO raw materials are added in an amount within the aforementioned range. The raw materials for SiO 2 and MgO are desirably those having a purity of 99% or more, and those having an average particle diameter of 1 μm or less that are easily mixed uniformly are desirable. However, when MgO is wet-mixed in an aqueous system, magnesium nitrate (Mg (NO 2 ) 3 .6H 2 O) may be mixed as an aqueous solution. As other raw materials for SiO 2 and MgO, high-purity clayey raw materials such as kaolin having a purity of 99 and 8% or more can also be used. The content of alkali metal in these SiO 2 and MgO raw materials is preferably 0.2 wt% or less, and most commercially available high-purity raw materials can be used.
[0013]
Water is added to the raw materials blended with these to form a slurry, which is mixed with a ball mill or the like. Preparation of the molded body is a method of adding a binder to the obtained slurry and press-molding the granules obtained by spray drying, a method of adding a binder to the slurry and casting using a gypsum mold, and drying the slurry, It can be produced by a conventional method such as injection molding by adding a binder.
[0014]
The obtained molded body is sintered at a temperature of 1500 ° C. or higher. Below this temperature, it is not desirable because it does not become dense. The sintering furnace may be a furnace made of a furnace material containing a large amount of alkali metal and having a large amount of alkali metal components volatilized.
[0015]
When blended so as to have the above composition and manufactured by the above method, an alumina sintered body having a low dielectric loss can be obtained even when a highly alkaline raw material is used or an alkali metal is mixed during the manufacturing process. be able to.
[0016]
【Example】
EXAMPLES Hereinafter, the Example of this invention is given with a comparative example, and this invention is demonstrated in detail.
[0017]
(Examples 1-4)
(1) Production of alumina sintered body Commercially available low alkali high purity alumina powder (SiO 2 : 0.02 wt%, MgO: 0.02 wt%, Na 2 O: 0.001 wt%, K 2 O: 0.001 wt) %) Is added to Aerosil (Aerosil 130: 99% purity of SiO 2 purity) as the SiO 2 source and magnesium nitrate as the MgO source so as to have the contents shown in Table 1, and water and a dispersant are added to the resin ball as a medium. Were mixed by a ball mill. PVA was added as a binder to the resulting slurry and spray dried to obtain granules. The obtained granules were subjected to CIP molding, and the molded body was sintered at a temperature shown in Table 1 in a furnace using a heat insulating material containing a large amount of alkali metal components to prepare a sintered body.
[0018]
(2) Evaluation The obtained sintered body was pulverized, and SiO 2 , MgO, Na, and K were quantified by chemical analysis, and the total amount and weight ratio of SiO 2 and MgO were determined. Further, the cordierite phase content was determined by XRD. Furthermore, the bulk specific gravity of the sintered body was determined by the Archimedes method, and the relative density was determined. Furthermore, the dielectric loss of the sintered body was determined by the current-voltage method. The results are shown in Table 1.
[0019]
(Examples 5-7)
(1) Production of alumina sintered body Commercially available high-purity alumina powder (SiO 2 : 0.03 wt%, MgO: 0.01 wt%, Na 2 O: 0.05 wt%, K 2 O: 0.04 wt%) In addition, the same SiO 2 source and MgO source as in Example 1 were added so as to have the contents shown in Table 1, mixed and molded in the same manner as in Example 1, and the molded body was baked and the alkali metal was sufficiently volatilized. The sintered body was produced by sintering at the temperature shown in Table 1 in the furnace.
[0020]
(2) Evaluation Evaluation was performed in the same manner as in Example 1 including the following examples. The results are shown in Table 1.
[0021]
(Example 8)
(1) Preparation of Alumina Sintered Body To the same alumina powder as in Example 5, high-purity kaolin (SiO 2 : 45.7 wt%, Al 2 O 3 : 38.0 wt%, MgO: 0.06 wt as the SiO 2 source) %, Na 2 O: 0.07 wt%, K 2 O: 0.13 wt%, loss on ignition: 14.6 wt%), and magnesium nitrate as an MgO source was added so as to have the contents shown in Table 1. 1 was mixed and molded in the same manner as in Example 1, and the molded body was sintered at the temperature shown in Table 1 in the same furnace as in Example 5 to produce a sintered body.
[0022]
Example 9
(1) Preparation of alumina sintered body The same alumina powder, SiO 2 source, and MgO source as in Example 5 were blended so as to have the contents shown in Table 1, and mixed in the same manner as in Example 5. The molded body was molded and sintered at the temperature shown in Table 1 in the same furnace as in Example 1 to prepare a sintered body.
[0023]
(Comparative Examples 1 to 8) For comparison, Comparative Example 1 is the same as Example 5 except that no SiO 2 or MgO source is added. In Comparative Examples 2 to 5 , the SiO 2 and MgO sources are within the scope of the present invention. Except for the addition of an external amount, in Comparative Example 6, the same as in Example 1 except that the sintering temperature of the molded body was outside the scope of the present invention. As in Example 8, except that No was added, in Comparative Example 8, a sintered body was prepared and evaluated in the same manner as in Example 1 except that the same furnace as in Example 5 was used for sintering. The results are also shown in Table 1.
[0024]
[Table 1]
As is clear from Table 1, the alumina sintered bodies of the examples all have an alkali metal content of 800-2100 ppm ( 0.08-0.21 wt%) and far exceeding 100 ppm (0.01 wt%). However, since they are dense alumina sintered bodies having a composition within the range of the present invention, the dielectric loss of each was 0.004 or less.
[0026]
On the other hand, in Comparative Example 1, since no cordierite phase is present without adding SiO 2 and MgO, in Comparative Example 2, since SiO 2 / MgO is lower than 2 and free MgO increases, Comparative Example 4 Then, even if SiO 2 and MgO are added, the amount is small and the cordierite phase is small. Therefore, in Comparative Example 5, the amount of SiO 2 and MgO is large and the cordierite phase is too large. The value was one digit larger than the example. In Comparative Example 3, since the SiO 2 is too large, in Comparative Example 6, since the sintering temperature is too low, since the the cordierite phase in Comparative Example 7 is almost no SiO 2 is too much, either Dielectric loss was still large due to insufficient sintering.
The comparative example 8 is a sintered body having a small dielectric loss similar to that of the example. This is a low alkali high purity alumina powder (unit price is about 10 times higher than non-low alkali alumina powder). ) And a sintered body having an alkali metal content of less than 100 ppm using a furnace with little alkali metal volatilization, using a non-low alkali alumina powder and containing a large amount of alkali metal components. Compared with Example 9 produced using the furnace which uses this, cost increased significantly.
[0027]
【The invention's effect】
As described above, if the alumina sintered body according to the present invention is used, an alumina sintered body having a dielectric loss at 100 kHz to 1 GHz of 0.004 or less can be obtained even if the alkali metal content greatly exceeds 100 ppm. did it. As a result, an alumina sintered body having a low dielectric loss can be obtained without much increase in cost.
Claims (1)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28899796A JP3888714B2 (en) | 1996-10-14 | 1996-10-14 | Alumina sintered body |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28899796A JP3888714B2 (en) | 1996-10-14 | 1996-10-14 | Alumina sintered body |
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| Publication Number | Publication Date |
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| JPH10120461A JPH10120461A (en) | 1998-05-12 |
| JP3888714B2 true JP3888714B2 (en) | 2007-03-07 |
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| JP4897163B2 (en) * | 2001-09-19 | 2012-03-14 | 太平洋セメント株式会社 | Method for producing alumina sintered body |
| JP6052249B2 (en) * | 2014-07-24 | 2016-12-27 | 株式会社デンソー | Alumina sintered body and spark plug |
| JP7154912B2 (en) * | 2017-10-05 | 2022-10-18 | クアーズテック株式会社 | Alumina sintered body and its manufacturing method |
| US11760694B2 (en) | 2017-10-05 | 2023-09-19 | Coorstek Kk | Alumina sintered body and manufacturing method therefor |
| JP7231367B2 (en) * | 2018-09-26 | 2023-03-01 | クアーズテック株式会社 | Alumina sintered body |
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