JPH0534305B2 - - Google Patents
Info
- Publication number
- JPH0534305B2 JPH0534305B2 JP62076464A JP7646487A JPH0534305B2 JP H0534305 B2 JPH0534305 B2 JP H0534305B2 JP 62076464 A JP62076464 A JP 62076464A JP 7646487 A JP7646487 A JP 7646487A JP H0534305 B2 JPH0534305 B2 JP H0534305B2
- Authority
- JP
- Japan
- Prior art keywords
- bending strength
- ultraviolet transmittance
- alumina
- specific surface
- surface area
- 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 - Lifetime
Links
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 31
- 239000000843 powder Substances 0.000 claims description 23
- 238000010304 firing Methods 0.000 claims description 13
- 238000005245 sintering Methods 0.000 claims description 13
- 239000000919 ceramic Substances 0.000 claims description 12
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 230000001590 oxidative effect Effects 0.000 claims description 5
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 4
- HSEYYGFJBLWFGD-UHFFFAOYSA-N 4-methylsulfanyl-2-[(2-methylsulfanylpyridine-3-carbonyl)amino]butanoic acid Chemical compound CSCCC(C(O)=O)NC(=O)C1=CC=CN=C1SC HSEYYGFJBLWFGD-UHFFFAOYSA-N 0.000 claims description 2
- 238000005452 bending Methods 0.000 description 22
- 238000002834 transmittance Methods 0.000 description 20
- 239000013078 crystal Substances 0.000 description 9
- 238000000465 moulding Methods 0.000 description 7
- 239000002245 particle Substances 0.000 description 6
- LCQXXBOSCBRNNT-UHFFFAOYSA-K ammonium aluminium sulfate Chemical compound [NH4+].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O LCQXXBOSCBRNNT-UHFFFAOYSA-K 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 239000011148 porous material Substances 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- 230000007423 decrease Effects 0.000 description 4
- PPQREHKVAOVYBT-UHFFFAOYSA-H dialuminum;tricarbonate Chemical compound [Al+3].[Al+3].[O-]C([O-])=O.[O-]C([O-])=O.[O-]C([O-])=O PPQREHKVAOVYBT-UHFFFAOYSA-H 0.000 description 4
- YIXJRHPUWRPCBB-UHFFFAOYSA-N magnesium nitrate Chemical compound [Mg+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O YIXJRHPUWRPCBB-UHFFFAOYSA-N 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 239000002202 Polyethylene glycol Substances 0.000 description 2
- 239000004372 Polyvinyl alcohol Substances 0.000 description 2
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 2
- 229940118662 aluminum carbonate Drugs 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229920001223 polyethylene glycol Polymers 0.000 description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 239000003966 growth inhibitor Substances 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 230000015654 memory Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 239000012780 transparent material Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Compositions Of Oxide Ceramics (AREA)
Description
（産業上の利用分野）
この発明は、アルミナセラミツクスの製造方法
に関し、とくに紫外線透過能の劣化を招くことな
しに曲げ強さの向上を図つたものであり、
EPROM（Erasable and Programmable Read
Onry Memory）用のパツケージなど紫外線透過
材料としての用途に用いてとりわけ好適なもので
ある。
（従来の技術）
EPROMにおいては、紫外線照射によつて半導
体メモリーの内容を消去して情報の書替えを行う
必要があることから、そのパツケージとしては、
少なくとも上面中央域（一般に窓と呼ばれてい
る）については透光性であることが必要とされ、
従来かかるEPROM用パツケージの窓材として
は、熱伝導率がいいこともあつて特公昭39−240
号公報や特公昭47−51801号公報などに開示の透
光性アルミナセラミツクスが用いられてきた。
（発明が解決しようとする問題点）
上掲の透光性アルミナセラミツクスは、従来、
主に高圧金属放電灯の発光管として使用されてい
たことから、とくに可視光領域の透過率が高いこ
とに重点がおかれ、そのため焼結助剤として
MgOなどを添加し、1750℃以上の高温で焼結し
て結晶粒径をできるだけ大きくしていた。
しかしながら結晶粒径を大きくした場合には、
機械的強度が著しく低い（2500Kgｆ／cm2程度）と
ころに問題を残していた。
ここにEPROM用パツケーシジの窓材として
は、ICカードの如き薄肉のロードシステムへの
適用やプラスチツクパツケージ化などの理由から
機械的強度とくに曲げ強さに優れることが必要と
される。
この発明は、上記の問題を有利に解決するもの
で、紫外線透過率を低下させることなしに曲げ強
さを大幅に向上させたアルミナセラミツクスの有
利な製造方法を提案することを目的とする。
（問題点を解決するための手段）
すなわちこの発明は、硫酸アルミニウムアンモ
ニウムを熱分解して得た純度：99.9wt％（以下単
に％で示す）以上でかつ比表面積が３〜10m2／ｇ
の酸化アルミニウム粉末に、焼結助剤として0.1
％以下のMgOと成形助剤とを添加したのち、所
定の形状に成形し、ついで露点が−15〜５℃の非
酸化性雰囲気中において、1450〜1600℃の温度範
囲で焼成することを特徴とするアルミナセラミツ
クスの製造方法である。
この発明に従つて得られるアルミナセラミツク
スは、純度：99.90％以上、結晶粒径：8μm以下
であつて、曲げ強さが5000Kgｆ／cm2以上で、しか
も厚み：0.2mmにおける波長：2537Åの紫外線透
過率が40％以上という、優れた曲げ強さおよび紫
外線透過率をそなえている。
ここに、99.9％以上の高純度が必要な理由は、
純度が99.9％に満たないと紫外線透過率が低下す
るだけでなく曲げ強さも低下するからであり、ま
た結晶粒径を8μm以下としたのは、結晶粒径が
8μmを超えると、たとえ純度が99.9％以上であつ
ても、充分満足のいく曲げ強さが得られないから
である。
以下、この発明を製造工程順に具体的に説明す
る。
さてこの発明では酸化アルミニウム粉末（以下
アルミナ粉末という）の原料として硫酸アルミニ
ウムアンモニウムを用いるが、その理由は、高純
度でしかも好適比表面積が得られるのみならず、
後述する焼成に際し、従来の透光性アルミナセラ
ミツクスの焼成温度に比べてはるかに低温で焼結
できるアルミナ粉末を容易に得ることができるか
らである。
ここに得られたアルミナ粉末の比表面積が３
m2／ｇに満たないと、焼結の進行が悪いだけでな
く、ポアが発生して紫外線透過率および曲げ強さ
とも小さいものしか得られず、一方10m2／ｇを超
えると、焼結が進み過ぎて、紫外線透過率は向上
するものの曲げ強さの劣化を招くので、アルミナ
粉末の比表面積は３〜10m2／ｇの範囲に限定し
た。
ところがかようなアルミナ粉末の比表面積は、
硫酸アルミニウムアンモニウムの熱分解時におけ
る処理条件とくに処理温度および時間に大きく影
響される。
ここに適正比表面積のアルミナ粉末を得る好適
処理条件について述べると、次のとおりである。
再結晶処理で高純度化した硫酸アルミニウムア
ンモニウム塩の結晶を高純度アルミナさや鉢に充
填し、これを電気炉にて加熱熱分解させたのち、
引続き1100〜1300℃に昇温し、少くとも30分乃至
５時間保持することによつて比表面積が３〜10
m2／ｇのα−結晶相のアルミナ粉末を得る。
アルミナ粉末が相変換することは良く知られて
いるが、処理温度が1100℃以下ではγ−結晶相の
アルミナが混在し、アルミナ製品を得る焼結時に
γからα相に変換して焼結の制御が困難になり所
望の製品が得られない。又1300℃以上では粉末粒
子間で反応が生じて疑素粒子化し、易焼結性が阻
害される。
また温度のみでは比表面積変化が激しいので時
間係数も加えて制御することが望ましく、均一な
粉末を得るためには少なくとも30分以上保持する
ことが好ましい。ただし５時間を越えて処理する
ことは工業的に好ましくない。
ついで得られたアルミナ粉末に焼結助剤を成形
助剤を添加してから、所定の形状に成形するわけ
であるが、成形法としては、たとえばチユーブや
棒状のものは押出し成形法が、他方EPROM用パ
ツケージの窓材のような板状のものはプレス成形
法が好適である。
焼結助剤は、MgOが最適である。MgOが透光
性アルミナセラミツクスの製造に於て粒成長抑制
剤として用いられることは公知であるが、この本
発明に於ても易焼結性のアルミナ粉末のみより
も、0.1％以下好ましくは0.03〜0.08％の範囲で
MgOを加えることにより、内在ポアーがなく結
晶粒が極めて均一な製品が得られることが分つ
た。これは、MgO分を予備焼成処理で熱分解し
てMgOとなる硝酸マグネシウムの水溶液で添加
したことによりMgO成分が極めて均一に分布し、
本焼成時に於てその焼結反応が成形素体の外表面
から初まりポアーを巻きこみ進行することを抑え
る効果をもつからと推測される。
また成形助剤の種類は、成形法に応じて定ま
り、たとえばプレス成形の場合は、結合材として
ポリビニールアルコール、滑材としてポリエチレ
ングリコールが有利に適合し、さらに両者を合計
した成形助剤の添加量については1.5〜3.0％程度
とするのが好ましい。
なお、かような成形助剤はいずれも、後述する
焼成において蒸発したり分解したりして最終的に
は焼結体から揮散するものであり、従つて製品中
に残存することはない。
その後、得られた成形体を大気中で予備焼成し
て成形助剤を分解、除去したのち、本焼成して製
品とするわけであるが、かかる本焼成は非酸化性
雰囲気中において行う必要がある。というのは非
酸化性以外の雰囲気ではポアを巻き込んで焼結が
進み強度ならびに紫外線透過性の低下を招くおそ
れが大きいからである。ここにかような焼成にお
いて、非酸化性雰囲気の露点を−15〜５℃とする
ことが肝要である。というのは露点が５℃より高
いと焼結の進行が悪く、一方−15℃を下回ると還
元力が強くなつて酸化アルミニウムの低次酸化物
が生成し、これが揮散してポアを形成するおそれ
が大きく、また低露点の高純度ガスは高価だから
でもある。
また焼成温度が1450℃に満たないと、焼結が充
分には進まないことから結晶粒界の結合度が弱
く、満足いく程の曲げ強さおよび紫外線透過率が
得られず、一方1600℃を超えると結晶粒径が大き
くなりすぎてやはり曲げ強さの低下を招くので、
焼成は1450〜1600℃の温度範囲で行なう必要があ
る。
なお焼成時間については、製品の大きさならび
に所望の強度（粒径）さらには設定温度によつて
異なるけれども0.5〜5h程度が好ましい。
（作用）
この発明に従うことによつて、紫外線透過率の
低下を招くことなしに優れた曲げ強さが得られる
理由は次のとおりと考えられる。
すなわち硫酸アルミニウムアンモニウムを熱分
解して得たアルミナ粉末は、易焼結性であり、
1600℃以下で理論密度の98％以上に容易に高密度
化でき、結晶粒径が8μm以下の均一な粒構造のア
ルミナセラミツクスとするのに適正な比表面積の
ものが容易に得られることによる。
（実施例）
硫酸アルミニウムアンモニウムを表１に示す
種々の条件で熱分解してアルミナ粉末を得た。
得られたアルミナ粉末の純度および比表面積を
表１に示す。
なお表１には比較のため、原料として炭酸アル
ミニウムおよび水酸化アルミニウムを用いた場合
についても併せて示した。
(Industrial Application Field) The present invention relates to a method for manufacturing alumina ceramics, and particularly aims to improve bending strength without causing deterioration of ultraviolet transmittance.
EPROM (Erasable and Programmable Read)
It is especially suitable for use as an ultraviolet-transparent material, such as in packages for private memories. (Prior art) In EPROM, since it is necessary to erase the contents of the semiconductor memory and rewrite the information by irradiating ultraviolet rays, the package is
At least the central area of the upper surface (commonly called the window) is required to be translucent.
Conventionally, the window material for such EPROM package has good thermal conductivity, and was
Transparent alumina ceramics disclosed in Japanese Patent Publication No. 47-51801 have been used. (Problems to be solved by the invention) The above-mentioned translucent alumina ceramics have conventionally
Since it was mainly used as an arc tube for high-pressure metal discharge lamps, emphasis was placed on its high transmittance in the visible light region, and therefore it was used as a sintering aid.
MgO and other substances were added and sintered at high temperatures of over 1,750°C to make the crystal grain size as large as possible. However, when increasing the grain size,
The problem remained that the mechanical strength was extremely low (approximately 2500 kgf/cm 2 ). The window material for the EPROM package needs to have excellent mechanical strength, especially bending strength, for reasons such as application to thin-walled load systems such as IC cards and the use of plastic packaging. The present invention advantageously solves the above-mentioned problems, and aims to propose an advantageous method for producing alumina ceramics that significantly improves bending strength without reducing ultraviolet transmittance. (Means for Solving the Problem) That is, the present invention provides a product obtained by thermally decomposing ammonium aluminum sulfate, which has a purity of 99.9 wt% or more (hereinafter simply expressed as %) and a specific surface area of 3 to 10 m 2 /g.
of aluminum oxide powder and 0.1 as a sintering aid.
% or less of MgO and a molding aid, then molded into a predetermined shape, and then fired at a temperature range of 1450 to 1600°C in a non-oxidizing atmosphere with a dew point of -15 to 5°C. This is a method for producing alumina ceramics. The alumina ceramics obtained according to the present invention has a purity of 99.90% or more, a crystal grain size of 8 μm or less, a bending strength of 5000 Kgf/cm 2 or more, and ultraviolet light transmission at a wavelength of 2537 Å at a thickness of 0.2 mm. It has excellent bending strength and ultraviolet transmittance, with a ratio of over 40%. Here, the reason why high purity of 99.9% or more is required is
This is because if the purity is less than 99.9%, not only the ultraviolet transmittance decreases but also the bending strength.The reason why the crystal grain size is set to 8μm or less is because the crystal grain size
If it exceeds 8 μm, even if the purity is 99.9% or more, sufficient bending strength cannot be obtained. Hereinafter, this invention will be specifically explained in the order of manufacturing steps. In this invention, aluminum ammonium sulfate is used as a raw material for aluminum oxide powder (hereinafter referred to as alumina powder), and the reason for this is that it not only has high purity and a suitable specific surface area, but also
This is because it is possible to easily obtain alumina powder that can be sintered at a much lower temperature than the firing temperature of conventional translucent alumina ceramics during firing, which will be described later. The specific surface area of the alumina powder obtained here is 3
If it is less than 10 m 2 /g, not only will the sintering process be slow, but pores will be generated, resulting in low ultraviolet transmittance and bending strength. The specific surface area of the alumina powder was limited to a range of 3 to 10 m 2 /g because if the alumina powder progresses too much, the ultraviolet transmittance improves but the bending strength deteriorates. However, the specific surface area of such alumina powder is
It is greatly influenced by the treatment conditions during thermal decomposition of ammonium aluminum sulfate, especially the treatment temperature and time. The preferred processing conditions for obtaining alumina powder with an appropriate specific surface area are as follows. Crystals of aluminum ammonium sulfate salt made highly purified through recrystallization treatment are filled into a high-purity alumina pod, and after being heated and pyrolyzed in an electric furnace,
By subsequently increasing the temperature to 1100-1300℃ and holding it for at least 30 minutes to 5 hours, the specific surface area becomes 3-10.
m 2 /g of α-crystal phase alumina powder is obtained. It is well known that alumina powder undergoes a phase transformation, but if the processing temperature is below 1100℃, alumina in the γ-crystalline phase will coexist, and during sintering to obtain an alumina product, the γ-crystalline phase will change and the γ-crystalline phase will change during sintering. Control becomes difficult and the desired product cannot be obtained. Moreover, at temperatures above 1300°C, reactions occur between powder particles, forming pseudoparticles, which impairs sinterability. Further, since temperature alone causes a drastic change in the specific surface area, it is desirable to add a time factor to the control, and in order to obtain a uniform powder, it is preferable to hold the temperature for at least 30 minutes or more. However, it is industrially undesirable to treat for more than 5 hours. Next, sintering aids and forming aids are added to the alumina powder obtained, and it is then formed into a predetermined shape.For example, extrusion is used to form tubes or rods, while other methods are used. Press molding is suitable for plate-shaped items such as window materials for EPROM packages. The best sintering aid is MgO. It is known that MgO is used as a grain growth inhibitor in the production of translucent alumina ceramics, but in the present invention, MgO is also used in an amount of 0.1% or less, preferably 0.03%, rather than using only easily sinterable alumina powder. In the range of ~0.08%
It was found that by adding MgO, a product with extremely uniform crystal grains without intrinsic pores could be obtained. This is because the MgO component is added as an aqueous solution of magnesium nitrate, which is thermally decomposed into MgO in the pre-calcination treatment, so that the MgO component is distributed extremely uniformly.
This is presumed to be because it has the effect of suppressing the sintering reaction that starts from the outer surface of the molded element and progresses by involving the pores during the main firing. In addition, the type of molding aid is determined depending on the molding method; for example, in the case of press molding, polyvinyl alcohol is advantageously suitable as a binder and polyethylene glycol as a lubricant. The amount is preferably about 1.5 to 3.0%. All such molding aids evaporate or decompose during the firing process, which will be described later, and are ultimately volatilized from the sintered body, so they do not remain in the product. Thereafter, the obtained molded body is pre-fired in the air to decompose and remove the forming aid, and then the product is produced by main firing, but this main firing must be carried out in a non-oxidizing atmosphere. be. This is because in an atmosphere other than a non-oxidizing one, pores are involved and sintering progresses, which is highly likely to cause a decrease in strength and ultraviolet transmittance. In such firing, it is important that the dew point of the non-oxidizing atmosphere is -15 to 5°C. This is because when the dew point is higher than 5℃, sintering progresses slowly, while when the dew point is lower than -15℃, the reducing power becomes strong and lower oxides of aluminum oxide are generated, which may volatilize and form pores. This is also because high purity gas with a low dew point is expensive. Furthermore, if the firing temperature is lower than 1450°C, sintering will not proceed sufficiently and the degree of bonding of grain boundaries will be weak, making it impossible to obtain satisfactory bending strength and ultraviolet transmittance. If it is exceeded, the crystal grain size will become too large, which will lead to a decrease in bending strength.
Firing must be carried out at a temperature range of 1450-1600°C. The firing time is preferably about 0.5 to 5 hours, although it varies depending on the size of the product, desired strength (particle size), and set temperature. (Function) The reason why excellent bending strength can be obtained without causing a decrease in ultraviolet transmittance by following the present invention is considered to be as follows. In other words, alumina powder obtained by thermally decomposing ammonium aluminum sulfate is easily sinterable.
This is because it can be easily densified to 98% or more of the theoretical density at temperatures below 1600°C, and it is easy to obtain alumina ceramics with a specific surface area suitable for producing alumina ceramics with a uniform grain structure with a crystal grain size of 8 μm or less. (Example) Ammonium aluminum sulfate was thermally decomposed under various conditions shown in Table 1 to obtain alumina powder. Table 1 shows the purity and specific surface area of the obtained alumina powder. For comparison, Table 1 also shows cases where aluminum carbonate and aluminum hydroxide were used as raw materials.
【表】
ついで得られた各粉末に、MgOとして0.07％
になるよう硝酸マグネシウムを加え、さらに成形
助剤としてポリビニールアルコールとポリエチレ
ングリコールとを2.5％添加したのち、適量の水
を加えてから、スプレードライヤーで造粒して平
均粒子径70〜90μmの粉末としたのち、12.5mm角、
厚み0.25mmの板にプレス成形した。
次に、得られた成形体を、表２に示す種々の条
件で焼成した。
かくして得られたアルミナセラミツクスの曲げ
強さ、紫外線透過率、密度および平均粒径につい
て調べた結果を表２に併記する。[Table] Then, 0.07% MgO was added to each powder obtained.
After adding magnesium nitrate to the desired temperature, and adding 2.5% polyvinyl alcohol and polyethylene glycol as molding aids, add an appropriate amount of water and granulate with a spray dryer to form a powder with an average particle size of 70 to 90 μm. After that, 12.5mm square,
It was press-formed into a plate with a thickness of 0.25 mm. Next, the obtained molded bodies were fired under various conditions shown in Table 2. Table 2 also shows the results of examining the bending strength, ultraviolet transmittance, density, and average particle size of the alumina ceramics thus obtained.
【表】
同表より明らかなように、原料として比較面積
がこの発明の下限を下回るアルミナ粉末を用いた
場合（No.７）は、曲げ強さおよび紫外線透過率と
も良好なものは得られなかつた。また焼成温度が
上限値を上回るNo.８は、粒径が大きく、紫外線透
過率は良好であつたが、曲げ強さに劣つていた。
一方焼成温度が下限値を下回るNo.９，10はいずれ
も、曲げ強さが低いだけでなく、紫外線透過率も
極めて悪かつた。
また焼結助剤としてのMgOが添加しなかつた
No.13は、曲げ強さ、紫外線透過率とも充分とは言
い難かつた。
原料として比表面積が大きすぎるアルミナ粉末
を用いた場合（No.14）は、粒子が大きくなりす
ぎ、紫外線透過率は良かつたものの曲げ強さに劣
つていた。
さらに原料として炭酸アルミニウムおよび水酸
化アルミニウムを用いた場合（No.15および16）は
それぞれ、曲げ強さおよび紫外線透過率とも低い
値しか得られなかつた。
これに対し、この発明の要件を満足するNo.１〜
６はいずれも、高い曲げ強さと共に良好な紫外線
透過率が得られた。
なおNo.11及び12はそれぞれ、雰囲気ガスの露点
が好適範囲の下限および上限を逸脱した比較例で
あるが、かような場合には曲げ強さか紫外線透過
率のいずれか一方しか良好な値は得られなかつ
た。
（発明の効果）
かくしてこの発明によれば、紫外線透過率を低
下させることなしに機械的強度とくに曲げ強さを
格段に向上させることができ、有利である。[Table] As is clear from the table, when alumina powder with a comparative area below the lower limit of this invention is used as a raw material (No. 7), good bending strength and ultraviolet transmittance cannot be obtained. Ta. Further, No. 8, in which the firing temperature exceeded the upper limit, had a large particle size and good ultraviolet transmittance, but was inferior in bending strength.
On the other hand, both Nos. 9 and 10, in which the firing temperature was below the lower limit, not only had low bending strength but also had extremely poor ultraviolet transmittance. In addition, MgO as a sintering aid was not added.
No. 13 had insufficient bending strength and ultraviolet transmittance. When alumina powder with too large a specific surface area was used as a raw material (No. 14), the particles became too large, and although the ultraviolet transmittance was good, the bending strength was poor. Furthermore, when aluminum carbonate and aluminum hydroxide were used as raw materials (Nos. 15 and 16), only low values of bending strength and ultraviolet transmittance were obtained, respectively. On the other hand, No. 1~ that satisfy the requirements of this invention
In all of No. 6, high bending strength and good ultraviolet transmittance were obtained. Note that Nos. 11 and 12 are comparative examples in which the dew point of the atmospheric gas deviates from the lower and upper limits of the preferred range, respectively, but in such cases, only one of the bending strength and ultraviolet transmittance has a good value. I couldn't get it. (Effects of the Invention) Thus, according to the present invention, mechanical strength, especially bending strength, can be significantly improved without reducing ultraviolet transmittance, which is advantageous.
Claims (1)
得た純度：99.9wt％以上でかつ比表面積が３〜10
m2／ｇの酸化アルミニウム粉末に、焼結助剤とし
て0.1wt％以下のMgOと成形助剤とを添加したの
ち、所定の形状に成形し、ついで露点が−15〜５
℃の非酸化性雰囲気中において、1450〜1600℃の
温度範囲で焼成することを特徴とするアルミナセ
ラミツクスの製造方法。1 Purity obtained by thermally decomposing aluminum ammonium sulfate: 99.9wt% or more and specific surface area 3 to 10
After adding 0.1wt% or less MgO as a sintering aid and a forming aid to m 2 /g of aluminum oxide powder, it is molded into a predetermined shape, and then the dew point is -15 to 5.
1. A method for producing alumina ceramics, which comprises firing in a non-oxidizing atmosphere at 1450 to 1600°C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62076464A JPS63242964A (en) | 1987-03-31 | 1987-03-31 | Alumina ceramics and manufacture |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62076464A JPS63242964A (en) | 1987-03-31 | 1987-03-31 | Alumina ceramics and manufacture |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63242964A JPS63242964A (en) | 1988-10-07 |
| JPH0534305B2 true JPH0534305B2 (en) | 1993-05-21 |
Family
ID=13605886
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62076464A Granted JPS63242964A (en) | 1987-03-31 | 1987-03-31 | Alumina ceramics and manufacture |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS63242964A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5256901A (en) * | 1988-12-26 | 1993-10-26 | Ngk Insulators, Ltd. | Ceramic package for memory semiconductor |
| DE69006609T2 (en) * | 1989-03-15 | 1994-06-30 | Ngk Insulators Ltd | Ceramic lid for closing a semiconductor element and method for closing a semiconductor element in a ceramic package. |
| JP2663191B2 (en) * | 1990-03-09 | 1997-10-15 | 通商産業省工業技術院長 | Method for producing polycrystalline alumina sintered body |
| CA2066604A1 (en) * | 1990-07-18 | 1992-01-19 | Koichi Hayashi | Variable color lamp |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54154413A (en) * | 1978-05-08 | 1979-12-05 | Ngk Spark Plug Co | Alphaaalumina sintered body production |
| JPS6045147A (en) * | 1983-08-22 | 1985-03-11 | 日東製器株式会社 | Vessel |
| JPS62187157A (en) * | 1986-02-10 | 1987-08-15 | 株式会社ニッカト− | Alumina member for crusher |
-
1987
- 1987-03-31 JP JP62076464A patent/JPS63242964A/en active Granted
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54154413A (en) * | 1978-05-08 | 1979-12-05 | Ngk Spark Plug Co | Alphaaalumina sintered body production |
| JPS6045147A (en) * | 1983-08-22 | 1985-03-11 | 日東製器株式会社 | Vessel |
| JPS62187157A (en) * | 1986-02-10 | 1987-08-15 | 株式会社ニッカト− | Alumina member for crusher |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63242964A (en) | 1988-10-07 |
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