JPH0274560A - Mullite-zirconia compound ceramics having high strength and toughness and production thereof - Google Patents
Mullite-zirconia compound ceramics having high strength and toughness and production thereofInfo
- Publication number
- JPH0274560A JPH0274560A JP63224478A JP22447888A JPH0274560A JP H0274560 A JPH0274560 A JP H0274560A JP 63224478 A JP63224478 A JP 63224478A JP 22447888 A JP22447888 A JP 22447888A JP H0274560 A JPH0274560 A JP H0274560A
- Authority
- JP
- Japan
- Prior art keywords
- mullite
- zirconia
- crystalline
- sol
- toughness
- 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.)
- Pending
Links
- MCMNRKCIXSYSNV-UHFFFAOYSA-N ZrO2 Inorganic materials O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 title claims abstract description 81
- 239000000919 ceramic Substances 0.000 title claims abstract description 24
- 238000004519 manufacturing process Methods 0.000 title claims description 13
- 239000000843 powder Substances 0.000 claims abstract description 34
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 14
- 229910001593 boehmite Inorganic materials 0.000 claims abstract description 13
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 claims abstract description 13
- 239000000203 mixture Substances 0.000 claims abstract description 13
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims abstract description 10
- 238000001354 calcination Methods 0.000 claims abstract description 6
- 239000002131 composite material Substances 0.000 claims description 37
- 238000000034 method Methods 0.000 claims description 14
- 238000005245 sintering Methods 0.000 claims description 13
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 abstract description 9
- 239000000126 substance Substances 0.000 abstract description 6
- 239000000463 material Substances 0.000 abstract description 4
- 150000001875 compounds Chemical class 0.000 abstract 4
- 229910052593 corundum Inorganic materials 0.000 abstract 2
- 229910001845 yogo sapphire Inorganic materials 0.000 abstract 2
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 description 14
- 229910052863 mullite Inorganic materials 0.000 description 14
- 238000010298 pulverizing process Methods 0.000 description 7
- BYFGZMCJNACEKR-UHFFFAOYSA-N Al2O Inorganic materials [Al]O[Al] BYFGZMCJNACEKR-UHFFFAOYSA-N 0.000 description 6
- 238000010304 firing Methods 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- 238000005452 bending Methods 0.000 description 4
- 238000000280 densification Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000000499 gel Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 229910017604 nitric acid Inorganic materials 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 2
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- VKYKSIONXSXAKP-UHFFFAOYSA-N hexamethylenetetramine Chemical compound C1N(C2)CN3CN1CN2C3 VKYKSIONXSXAKP-UHFFFAOYSA-N 0.000 description 2
- 238000000462 isostatic pressing Methods 0.000 description 2
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- CMOAHYOGLLEOGO-UHFFFAOYSA-N oxozirconium;dihydrochloride Chemical compound Cl.Cl.[Zr]=O CMOAHYOGLLEOGO-UHFFFAOYSA-N 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 238000003980 solgel method Methods 0.000 description 2
- OERNJTNJEZOPIA-UHFFFAOYSA-N zirconium nitrate Chemical compound [Zr+4].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O OERNJTNJEZOPIA-UHFFFAOYSA-N 0.000 description 2
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 1
- 229910005091 Si3N Inorganic materials 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
- 238000007545 Vickers hardness test Methods 0.000 description 1
- 229910006501 ZrSiO Inorganic materials 0.000 description 1
- YKTSYUJCYHOUJP-UHFFFAOYSA-N [O--].[Al+3].[Al+3].[O-][Si]([O-])([O-])[O-] Chemical group [O--].[Al+3].[Al+3].[O-][Si]([O-])([O-])[O-] YKTSYUJCYHOUJP-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 235000019253 formic acid Nutrition 0.000 description 1
- 229910021485 fumed silica Inorganic materials 0.000 description 1
- 239000004312 hexamethylene tetramine Substances 0.000 description 1
- 235000010299 hexamethylene tetramine Nutrition 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 150000007522 mineralic acids Chemical class 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 229910002077 partially stabilized zirconia Inorganic materials 0.000 description 1
- 238000013001 point bending Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical group N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
- 238000001238 wet grinding Methods 0.000 description 1
- 229910052845 zircon Inorganic materials 0.000 description 1
- 150000003754 zirconium Chemical class 0.000 description 1
- GFQYVLUOOAAOGM-UHFFFAOYSA-N zirconium(iv) silicate Chemical compound [Zr+4].[O-][Si]([O-])([O-])[O-] GFQYVLUOOAAOGM-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Compositions Of Oxide Ceramics (AREA)
Abstract
Description
ムライトは３Ａｌ２Ｏ．・２ＳｉＯ，の化学組成を有す
るケイ酸アルミニウムであり、その高純度焼結体は高温
強度、耐高温クリープ抵抗性、低熱膨張率等の熱的・Ｒ
賊的特性に優れていることから、高温構造材用セラミッ
クスとしての応用が進みつつある。
しかしながら、ムライトは窒化ケイ素（Ｓｉ３Ｎ＜）、
炭化ケイ素（ＳｉＣ）、部分安定化ジルコニア（ｐｓｚ
）等の構造材料用セラミックスに比較して、室温におけ
る抗折強度、破壊靭性が低く、これらの機械的特性の改
善が望まれている。
そして、これらの機械的特性の改善方法として、ウィス
カー（ひげ状単結晶）やジルコニア（ＺｒＯｔ）微粒子
をセラミックスマトリックス中に分散強化する方法が提
案されている。
これらの提案のうち前者の方法は、ウィスカーによる補
強効果が大きい特徴を有しているものの、その均一分散
が難しく、かつ、緻密な焼結体を得るには特殊な熱間加
熱焼結装置を必要とし、さらにはウィスカー自体高価な
材料である為、実用化の域に達するには多くの問題が未
解決のまま残されている。
これに対して、ジルコニアの添加によりムライトの焼結
性や機械的特性が向上することの報告がＮ、 Ｃ１ａｕ
ｓｓｅｎ ａｎｃｌ Ｊ、 Ｊａｈｎ（Ｊ、 ｏｒ Ｌ
ｈｅＡｍｅｒｉｅａｎＣｅｒａｍ、 Ｓｏｅ、 Ｖｏｌ
、６３．Ｎｏ、３−４，２２８〜２２９）番こよってな
されて以来、ムライト−ジルコニア系複合セラミックス
の研究が盛んに行なわれてきている。
そして、このような研究開発によって、天然産のジルコ
ン（ＺｒＳｉＯ＜）とアルミナを、あるいはムライトと
ジルコニアを機械的に混合粉砕して粉末を得、この粉末
の成型体を焼成することによりムライト−ジルコニア系
複合セラミックスを得る技術が提案されてきた。
しかし、これらの方法では、原料の均一混合や微粉砕に
長時間を要する為、混合粉砕工程による不純物混入は避
けられず、又、高温焼成時に多大なエネルギーを消費す
る為、高品質のムライト−ジルコニア複合粉末の工業的
製法としては適当でない上、ジルコニアが均一に分散さ
れた原料粉末を得ることは困難であり、従って焼結体の
微細構造を制御することが難しい。
特に、ムライトとジルコニアはその熱膨張係数に大きな
差があるため、ジルユニアの分散が不均一な場合、焼結
後室温まで冷却する間に局部的な熱応力が発生し、この
為焼結体中に多数の微細なりラックが生じ、高強度焼結
体を製造する上でこれが大きな問題となっていた。
又、従来の方法では正方品ジルコニア比率が低いことか
ら、強度等の特性向上効果が大きく得られていないこと
も判ってきた。Mullite is 3Al2O.・It is an aluminum silicate with a chemical composition of 2SiO, and its high-purity sintered body has excellent thermal and R properties such as high-temperature strength, high-temperature creep resistance, and low coefficient of thermal expansion.
Due to its excellent thermal properties, its application as ceramics for high-temperature structural materials is progressing. However, mullite is silicon nitride (Si3N<),
Silicon carbide (SiC), partially stabilized zirconia (psz
) have lower bending strength and fracture toughness at room temperature, and improvements in these mechanical properties are desired. As a method for improving these mechanical properties, a method has been proposed in which whiskers (beard-like single crystals) or zirconia (ZrOt) fine particles are dispersed and strengthened in a ceramic matrix. Of these proposals, the former method has the feature of a large reinforcing effect due to the whiskers, but it is difficult to uniformly disperse them, and special hot heating sintering equipment is required to obtain a dense sintered body. Furthermore, since the whisker itself is an expensive material, many problems remain unresolved before it can be put into practical use. On the other hand, it has been reported that the addition of zirconia improves the sinterability and mechanical properties of mullite.
ssen ancl J, Jahn(J, or L
heAmerianCeram, Soe, Vol.
, 63. No. 3-4, 228-229) Since their discovery, research on mullite-zirconia composite ceramics has been actively conducted. Through such research and development, we obtained powder by mechanically mixing and pulverizing naturally occurring zircon (ZrSiO<) and alumina, or mullite and zirconia, and by firing a molded body of this powder, we produced mullite-zirconia. Techniques for obtaining composite ceramics have been proposed. However, with these methods, it takes a long time to uniformly mix and pulverize the raw materials, so it is inevitable that impurities are mixed in during the mixing and pulverizing process.Also, a large amount of energy is consumed during high-temperature firing, so high quality mullite cannot be obtained. In addition to being unsuitable as an industrial method for producing zirconia composite powder, it is difficult to obtain a raw material powder in which zirconia is uniformly dispersed, and therefore it is difficult to control the fine structure of the sintered body. In particular, since mullite and zirconia have a large difference in their coefficients of thermal expansion, if the dispersion of zirconia is uneven, local thermal stress will occur during cooling to room temperature after sintering, and this will cause A large number of fine racks are generated in the sintered body, which poses a major problem in producing high-strength sintered bodies. It has also been found that the conventional method does not significantly improve properties such as strength because the proportion of square zirconia is low.
本発明の目的は、高温特性及び化学的耐久性に潰れるム
ライト質セラミックスの機械的特性をさらに向上させた
ムライト−ジルコニア複合セラミックス及びゾル−ゲル
法という化学的合成法を用いたムライト−ジルコニア複
合セラミックスの製造方法を提供することにある。
上記の目的は、結晶性のδ−Ａｌ２Ｏ．と、結晶性のｔ
−ＺｒＯ２と、アモルファスシリカとの複合物からなる
ムライト−ジルコニア複合粉末を焼結してなる高強度・
高靭性ムライト−ジルコニア複合セラミックスによって
達成される。
尚、上記の高強度・高靭性ムライト−ジルコニア複合セ
ラミックスにおいて、ムライト−ジルコニア複合粉末に
おける結晶性のδ−Ａｌ２Ｏ，１００モルに対して結晶
性のｔ−Ｚｒ０□が約９４モル以下であり、この結晶性
のδ−Ａｌ２Ｏ．と結晶性のＬ−Ｚｒ０２の合計１１０
０体積部に対してアモルファスシリカが約２４体積部以
上、そして好ましくは約６２体積部以下であるものが望
ましく、又、結晶性のδ−Ａｌ２Ｏ．はその径が約１０
ｏｎ−以下、より好ましくは約２０〜５０ｎｍであり、
そして結晶性のｔ−Ｚｒ０□はその径が約５Ｏｎ−以下
、より好ましくは約１０〜２０ｎ輪であるものが望まし
く、又、この複合粉末はその比表面積が約２０〜５５＋
ｍ”／Ｈであるものが望ましく、又、この複合粉末の凝
集物の凝集粒径は約１〜１．３μであるものが望ましく
、叉、鐙−Ｚｒ０２が複合粉末中にｔ−ＺｒＪ１００モ
ルに対して１５０モル以下含有されていても良い
又、ベーマイトゾルとシリカゾルとの混合物にジルコニ
アゾルを加えてゲル化させ、その後約１１５０〜１２５
０℃で仮焼して得られる複合粉末を約り００℃／ｈｒ以
下、より好ましくは約２００〜３００℃／ｈｒの条件で
約１２００℃まで昇温させ、その後は約り００℃／ｈｒ
以下、より好ましくは約８０〜１００℃／ｈｒの条件で
約１５５０〜１６５０℃に昇温させて焼結する高強度・
高靭性ムライト−ジルコニア複合セラミックスの製造方
法によって、高温特性及び化学的耐久性に優れるムライ
ト質セラミックスの機械的特性をさらに向上させたムラ
イト−ジルコニア複合セラミックスが得られる。
尚、上記の高強度・高靭性ムライト−ジルコニア複合セ
ラミックスの製造方法において、ベーマイトゾルとシリ
カゾルの＾ｌ／Ｓｉのモル比は約１．５〜２．８７であ
るものが望ましく、又、ジルコニアゾルの添加量はＺ「
０．換算で約３０体積％以下、好ましくは約５〜２０体
積％、より一層好ましくは約１０〜２０体積％であるも
のが望ましい。
ところで、本発明者らは、ゾル−ゲル法によるジルコニ
ア均一分散ムライト質微粉末の製造方法（特開昭６２−
２０２８１３）を提案していたが、その後鋭意研究を重
ねた結果、すなわち上記の発明は、ベーマイトゾルとシ
リカゾルの＾ｌ／Ｓｉのモル比を１．５〜２．８７とし
た混合物にジルコニアゾルをＺｒＯ□換算で３０体積％
以下加えてゲル化させ、乾燥、粉砕したものを約１１５
０〜１２５０℃で仮焼することによって、易焼結性のム
ライト・ジルコニア複合粉末を製造できたことに基づい
て達成されたものである。
ここで、ベーマイトゾルとしては反応活性の高いベーマ
イトゾルを使用することが好ましいが、これはガンマ−
アルミナ（γ−＾ＬＬ）やベーマイト（八ｆ００１１）
の水分散液を８０℃以上に加熱しながら、硝酸、塩酸等
の無機酸や酢酸、ギ酸等の有機酸を＊ｉ加えて、解膠す
ることによって得られる。
シリカゾルとしては、シリカ微粒子、例えば湿式法で製
造されるホワイトカーボンや乾式法のヒユームドシリカ
を酸性水中に分散させたコロイド水ン容液が好ましい。
ジルコニアゾルは、オキシ塩化ジルコニウム、硝酸ジル
コニウム等のジルコニウム塩の水溶液に、それに含まれ
る塩酸、硝酸を中和させる目的で尿素やヘキサメチレン
テトラミンを加えることによって得られる。
そして、まず、前記のベーマイトゾルとシリカゾルを＾
ｌ／Ｓｉのモル比をムライトの理論組成及びアルミナと
の固溶体を形成する１、５〜２．８７の範囲内に調製す
る。尚、この範囲外での組成では、最終的に遊離のシリ
カやアルミナが生成し、焼結体特性に悪影響を及ぼすの
で好ましくない。
次に、上記の混合物にジルコニアゾルを加えてゲル化さ
せる。
このＺｒＬ添加量は３０体積％以下、特に好ましくは約
１０〜２０体積％であることが望ましい、尚、３０体積
％を越える場合は、焼結体にした時の機械的強度が低下
するので好ましくない、逆に、少なすぎる場合は破壊靭
性の向上が小さい。
ベーマイトゾルとシリカ微粒子の＾ｌ／Ｓ’＋のモル比
を１．５〜２．８７とした混合物にジルコニアゾルをｚ
ｒＯｄａ算で５〜２０体槓％加えて、ゲル化させ、乾燥
、粉砕した後に、約１１５０〜１２５０℃で仮焼して得
られる原料微粉末を、水スラリーを使った湿式法により
１〜２μ−に微粉砕する。ここで焼成温度を限定してい
るが、１１５０℃未満の低すぎる温度では粉末中にγ−
Ａｌ２Ｏ．相が残存し、これが湿式粉砕の際に水和物と
なって固い多孔性の凝集粒子を形成し、その後の微粉化
を困難にし、かつ、得られる粉末も多孔質の粗雑な構造
の粒子から構成される為、焼結時の緻密化を著しく阻害
して好ましくないからである。すなわち、１１５０℃以
上の温度で焼成することによって、複合粉末中にγ−Ａ
ｌ２Ｏ３が実質的に含まれないものが得られる。
逆に、１２５０℃を越えた高すぎる温度では、結晶質ム
ライトが生成するが、それに伴って粉末の比表面積及び
活性度が低下する為、緻密化の進行が妨げられる。
焼成温度を限定するもう一つの理由は、複合粉末中のジ
ルコニア結晶の粒径に関する点である。
複合粉末を微細かつ均一にすることが原料特性として望
ましい、ところで、 １２５０℃以下では、正方晶ジル
コニアはおよそ１０〜ＺｏｎＩＩＩの範囲にあり好まし
いが、この温度を越えると急激にその大きさが増大し、
これが粉末の活性度及び焼結体の機械的特性を向上させ
る正方晶ジルコニア比率の低下につながり、好ましくな
いのである。
このようにして製造された原料微粉末を金型成型法もし
くは静水圧成形法により所望の成型体とする。
この成型体を電気炉に入れ、大気中で焼成する。
昇温速度は１２００℃まで３００℃／ｈｒ以下、焼結温
度までは１００℃／ｈｒ以下とすることが望ましい、昇
温速度をこのように限定した理由は、成形体の焼結によ
る収縮のほとんどは１２００℃以降で起きる為である。
特に、１３００℃付近ではムライトの生成反応が起る。
そして、１２００℃以上での昇温速度をこの速度より大
きくすると、緻密化、結晶化が充分でなく、高密度の焼
結体が得られない。
焼結温度は約１５５０〜１６５０℃とし、この温度で数
時間保持したのち、室温まで自然放冷する。
焼結温度を限定しているのは、焼結体の緻密化を充分に
させる為である。 １５５０℃未満の低すぎる温度では
理論密度の９５％以上の緻密化が困難である。特に、高
強度の焼結体を製造する場合には約１６１０〜１６５０
℃での焼結が望ましい、この範囲の温度では理論密度の
９９％以上にまで密度が向上する。
しかしながら、１６５０℃を越えた高すぎる温度で焼結
を行うと、残留気孔により、密度が低下し、かつ粒成長
により強度低下の原因となって好ましくない。The purpose of the present invention is to create a mullite-zirconia composite ceramic that further improves the mechanical properties of mullite ceramics that are susceptible to high-temperature properties and chemical durability, and a mullite-zirconia composite ceramic that is produced using a chemical synthesis method called the sol-gel method. The purpose of this invention is to provide a method for manufacturing the same. The above purpose is to obtain crystalline δ-Al2O. and crystalline t
- High-strength product made by sintering mullite-zirconia composite powder, which is a composite of ZrO2 and amorphous silica.
Achieved by high toughness mullite-zirconia composite ceramics. In addition, in the above-mentioned high-strength and high-toughness mullite-zirconia composite ceramic, crystalline t-Zr0□ is about 94 mol or less per 100 mol of crystalline δ-Al2O in the mullite-zirconia composite powder, and this Crystalline δ-Al2O. and crystalline L-Zr02 total 110
Amorphous silica is preferably about 24 parts by volume or more, and preferably about 62 parts by volume or less, based on 0 parts by volume, and crystalline δ-Al2O. Its diameter is about 10
on- or less, more preferably about 20 to 50 nm,
It is desirable that the crystalline t-Zr0□ has a diameter of about 5On- or less, more preferably about 10 to 20n rings, and this composite powder has a specific surface area of about 20 to 55+
m”/H, and the aggregate particle size of the aggregates of this composite powder is preferably about 1 to 1.3μ, and the stirrup-Zr02 is contained in the composite powder in an amount of 100 moles of t-ZrJ. Alternatively, zirconia sol may be added to a mixture of boehmite sol and silica sol to form a gel, and then about 1150 to 125 moles or less may be contained.
The composite powder obtained by calcining at 0°C is heated to about 1200°C under conditions of about 00°C/hr or less, more preferably about 200 to 300°C/hr, and then heated to about 1200°C at about 00°C/hr or less.
Hereinafter, high-strength sintering is performed by raising the temperature to approximately 1,550 to 1,650°C under conditions of more preferably approximately 80 to 100°C/hr.
By the method for producing a high-toughness mullite-zirconia composite ceramic, it is possible to obtain a mullite-zirconia composite ceramic that has further improved mechanical properties of a mullite ceramic that has excellent high-temperature properties and chemical durability. In addition, in the above-mentioned method for producing high-strength and high-toughness mullite-zirconia composite ceramics, it is desirable that the molar ratio of ^l/Si between the boehmite sol and the silica sol is about 1.5 to 2.87; The amount of addition is Z'
0. It is desirable that the amount is about 30% by volume or less, preferably about 5 to 20% by volume, and even more preferably about 10 to 20% by volume. By the way, the present inventors have developed a method for producing zirconia uniformly dispersed mullite fine powder by a sol-gel method (Japanese Patent Application Laid-Open No. 1986-62-1).
202813), but as a result of extensive research, the above invention was developed by adding zirconia sol to a mixture of boehmite sol and silica sol with a molar ratio of ^l/Si of 1.5 to 2.87. 30 volume% in terms of ZrO□
Approximately 115 g of the following added, gelled, dried, and crushed
This was achieved based on the fact that an easily sinterable mullite-zirconia composite powder could be produced by calcining at 0 to 1250°C. Here, as the boehmite sol, it is preferable to use a boehmite sol with high reaction activity, but this
Alumina (γ-^LL) and boehmite (8f0011)
It is obtained by peptizing an aqueous dispersion by adding an inorganic acid such as nitric acid or hydrochloric acid or an organic acid such as acetic acid or formic acid while heating the aqueous dispersion to 80° C. or higher. The silica sol is preferably a colloidal water solution in which fine silica particles, such as white carbon produced by a wet method or fumed silica produced by a dry method, are dispersed in acidic water. Zirconia sol is obtained by adding urea or hexamethylenetetramine to an aqueous solution of a zirconium salt such as zirconium oxychloride or zirconium nitrate for the purpose of neutralizing hydrochloric acid and nitric acid contained therein. First, add the above-mentioned boehmite sol and silica sol.
The molar ratio of l/Si is adjusted within the range of 1.5 to 2.87, which forms a solid solution with the theoretical composition of mullite and alumina. Incidentally, a composition outside this range is not preferable because free silica or alumina will eventually be produced, which will have an adverse effect on the properties of the sintered body. Next, zirconia sol is added to the above mixture to form a gel. The amount of ZrL added is desirably 30% by volume or less, particularly preferably about 10 to 20% by volume. If it exceeds 30% by volume, the mechanical strength of the sintered body will decrease, so it is preferable. On the contrary, if it is too small, the improvement in fracture toughness will be small. Zirconia sol was added to a mixture of boehmite sol and silica fine particles with a molar ratio of ^l/S'+ of 1.5 to 2.87.
The raw material fine powder obtained by adding 5 to 20 mol% of rOda, gelling it, drying it, pulverizing it, and calcining it at about 1150 to 1250 degrees Celsius is 1 to 2μ by a wet method using water slurry. - Finely grind. Although the firing temperature is limited here, if the temperature is too low (less than 1150℃), γ-
Al2O. Phases remain, which become hydrated during wet milling to form hard, porous, aggregated particles, making subsequent pulverization difficult, and the resulting powder also consists of porous, coarsely structured particles. This is because it is undesirable because it significantly inhibits densification during sintering. That is, by firing at a temperature of 1150°C or higher, γ-A is added to the composite powder.
A substance substantially free of l2O3 is obtained. On the other hand, if the temperature is too high, exceeding 1250° C., crystalline mullite will be produced, but the specific surface area and activity of the powder will decrease accordingly, and the progress of densification will be hindered. Another reason for limiting the firing temperature is related to the particle size of the zirconia crystals in the composite powder. It is desirable for the raw material properties to make the composite powder fine and uniform. By the way, at temperatures below 1250°C, tetragonal zirconia is preferably in the range of about 10 to Zon III, but above this temperature, its size increases rapidly. ,
This is undesirable because it leads to a decrease in the tetragonal zirconia ratio, which improves the activity of the powder and the mechanical properties of the sintered body. The raw material fine powder thus produced is formed into a desired molded body by molding with a mold or isostatic pressing. This molded body is placed in an electric furnace and fired in the atmosphere. It is desirable that the temperature increase rate be 300℃/hr or less up to 1200℃ and 100℃/hr or less up to the sintering temperature.The reason for limiting the temperature increase rate in this way is that most of the shrinkage due to sintering of the compact This is because this occurs at temperatures above 1200°C. In particular, a mullite production reaction occurs at around 1300°C. If the temperature increase rate at 1200° C. or higher is higher than this rate, densification and crystallization will not be sufficient and a high-density sintered body will not be obtained. The sintering temperature is about 1550 to 1650°C, and after being maintained at this temperature for several hours, it is allowed to cool naturally to room temperature. The reason why the sintering temperature is limited is to sufficiently densify the sintered body. If the temperature is too low, below 1550°C, it is difficult to achieve densification of 95% or more of the theoretical density. In particular, when manufacturing high-strength sintered bodies, approximately 1610 to 1650
Sintering at a temperature of 0.degree. C. is preferred; at temperatures within this range, the density increases to over 99% of the theoretical density. However, sintering at a temperature that is too high, exceeding 1650° C., is undesirable because residual pores cause a decrease in density and grain growth causes a decrease in strength.
市販のベーマイト粉末を８０℃以上の熱硝酸水溶液に分
散させ、アルミナゾルを作る。
このアルミナゾルに所定のシリカゾルを＾１／Ｓ：のモ
ル比がムライト理論組成の１．５になるように加え、高
速ブレンダーにより撹拌混合した。
これにオキシ塩化ジルコニウム（ＺｒＯＣＺ２・８Ｈ，
０）の加水分解によって得たジルコニアゾルをＺ「０２
換算で０．５．１０．１５．２０体積％となるＩ各々加
え、ＡＬＬ−Ｓ！Ｌ−ＺｒＬ混合ゲルを作った。
これらのゲルを１００℃で乾燥した後、アルミナ製ボー
ルミルを用いて粉砕し、電気炉に入れて大気中において
１２００℃で１時間仮焼した。
仮焼後の粉砕を水スラリーとしてアトリッションミルを
用い、平均粒子径が約１μになるまで粉砕する。
この粉砕前の複合粉末の結晶相はδ−Ａｌ２Ｏ．及びｔ
−ＺｒＯ２のみである。尚、粉砕後における複合粉末に
あっては、ｔ−ＺｒＪの５０モル％が−ＺｒＯｔに転移
しているにすぎない、又、焼成粉末は５０ｎ−以下のδ
−＾１ｚＬＣその平均径２５ｎｓ）とｔ−ＺｒＬ（その
平均径１３ｎｍ）の均一複合粉末であり、又、複合粉末
における結晶性のδ−＾１！０３と結晶性のｔ−Ｚｒ０
□との割合はモル比で約１００対３９であり、この結晶
性のδ−＾１□０．と結晶性のｔ−ＺｒＯ２の合計量１
００体積部に対してアモルファスシリカは約４８体°積
部であった。
又、この粉末の比表面積（Ｎ２ガス吸着、Ｂ、Ｅ、Ｔ。
法）は約５１輪”／ｇであった。
そして、これを乾燥した後、１５０メツシユのふるいで
整粒し、２ｔｏｎ／ａｆｉ２の圧力で静水圧成形した成
形体を電気炉に入れ、１２００℃までは３００℃／ｈｒ
、その後は１６５０℃まで１００℃／ｈｒの昇温速度で
昇温させ、大気中にて１６５０℃で３時間焼結した。
このようにして得られた焼結体から３ｘ ４ｘ ４０ｍ
ｍの試験片を切り出し、ＪＩＳ３点法に従って、室温に
おける３点曲げ強度を測定した。
又、破壊靭性にｌｅ値をビッカース圧子押し込み法によ
り求めた。
その結果を第１図に示した０図中、曲げ強度を○印、破
壊靭性をΔ印で示す。
これかられかるようにＺｒＯ２含有量が５〜２０体積％
において曲げ強度は４００８Ｐａ以上の高強度を示し、
破壊靭性も３．４８Ｐａ饋”’以上と向上していること
がわかる。
次に、複合粉末及び焼結体の緒特性を表にして示す。Commercially available boehmite powder is dispersed in a hot nitric acid aqueous solution at 80°C or higher to make an alumina sol. A predetermined silica sol was added to this alumina sol so that the molar ratio of ^1/S: was 1.5 of the theoretical mullite composition, and the mixture was stirred and mixed using a high-speed blender. To this, zirconium oxychloride (ZrOCZ2.8H,
The zirconia sol obtained by hydrolysis of Z'02
Add each I which is 0.5, 10, 15, 20 volume % in conversion, ALL-S! An L-ZrL mixed gel was made. After drying these gels at 100°C, they were ground using an alumina ball mill, placed in an electric furnace, and calcined at 1200°C in the atmosphere for 1 hour. The pulverization after calcination is made into a water slurry and is pulverized using an attrition mill until the average particle size becomes about 1 μm. The crystal phase of this composite powder before pulverization is δ-Al2O. and t
-ZrO2 only. In addition, in the composite powder after pulverization, only 50 mol% of t-ZrJ has been transferred to -ZrOt, and the fired powder has a δ of 50n- or less.
-^1zLC (its average diameter is 25 ns) and t-ZrL (its average diameter is 13 nm).
□ is about 100:39 in molar ratio, and this crystalline δ-^1□0. and the total amount of crystalline t-ZrO2 1
The amount of amorphous silica was approximately 48 parts by volume. In addition, the specific surface area of this powder (N2 gas adsorption, B, E, T method) was about 51"/g. After drying, it was sized with a 150 mesh sieve and 2 tons/g. The compact formed by isostatic pressing at a pressure of afi2 is placed in an electric furnace, and heated at 300°C/hr up to 1200°C.
Thereafter, the temperature was raised to 1650°C at a temperature increase rate of 100°C/hr, and sintered at 1650°C for 3 hours in the atmosphere. 3x 4x 40m from the sintered body thus obtained
A test piece of m was cut out, and the three-point bending strength at room temperature was measured according to the JIS three-point method. Further, the le value of the fracture toughness was determined by the Vickers indentation method. The results are shown in Figure 1, in which the bending strength is indicated by ◯ and the fracture toughness is indicated by ∆. As you will see, the ZrO2 content is 5-20% by volume.
The bending strength shows a high strength of 4008 Pa or more,
It can be seen that the fracture toughness is also improved to 3.48 Pa'' or more.Next, the properties of the composite powder and sintered body are shown in a table.
第１図はＺｒＯ，の添加量と焼結体の曲げ強度及び破壊
靭性との関係を示すグラフである。FIG. 1 is a graph showing the relationship between the amount of ZrO added and the bending strength and fracture toughness of the sintered body.
Claims (6)
ｒＯ＿２と、アモルファスシリカとの複合物からなるム
ライト−ジルコニア複合粉末を焼結したことを特徴とす
る高強度・高靭性ムライト−ジルコニア複合セラミック
ス。(1) Crystalline δ-Al_2O_3 and crystalline t-Z
A high-strength, high-toughness mullite-zirconia composite ceramic characterized by sintering a mullite-zirconia composite powder made of a composite of rO_2 and amorphous silica.
イト−ジルコニア複合セラミックスにおいて、複合粉末
における結晶性のδ−Ａｌ＿２Ｏ＿３１００モルに対し
て結晶性のｔ−ＺｒＯ＿２が約９４モル以下であり、こ
の結晶性のδ−Ａｌ＿２Ｏ＿３と結晶性・のｔ−ＺｒＯ
＿２の合計量１００体積部に対してアモルファスシリカ
が約２４体積部以上であるもの。(2) In the high-strength and high-toughness mullite-zirconia composite ceramic according to claim 1, the amount of crystalline t-ZrO_2 is about 94 mol or less per 3100 mol of crystalline δ-Al_2O_2 in the composite powder. , this crystalline δ-Al_2O_3 and crystalline t-ZrO
The amount of amorphous silica is approximately 24 parts by volume or more per 100 parts by volume of the total amount of _2.
イト−ジルコニア複合セラミックスにおいて、複合粉末
における結晶性のδ−Ａｌ＿２Ｏ＿３はその径が約１０
０ｎｍ以下であり、結晶性のｔ−ＺｒＯ＿２はその径が
約５０ｎｍ以下であるもの。(3) In the high-strength and high-toughness mullite-zirconia composite ceramic according to claim 1, the crystalline δ-Al_2O_3 in the composite powder has a diameter of about 10
0 nm or less, and crystalline t-ZrO_2 has a diameter of about 50 nm or less.
ニアゾルを加えてゲル化させ、その後約１１５０〜１２
５０℃で仮焼して得られる複合粉末を約３００℃／ｈｒ
以下の条件で約１２００℃まで昇温させ、その後は約１
００℃／ｈｒ以下の条件で約１５５０〜１６５０℃に昇
温させて焼結することを特徴とする高強度・高靭性ムラ
イト−ジルコニア複合セラミックスの製造方法。(4) Add zirconia sol to the mixture of boehmite sol and silica sol to gel it, and then
The composite powder obtained by calcining at 50℃ is heated at about 300℃/hr.
Raise the temperature to about 1200℃ under the following conditions, and then increase the temperature to about 1200℃.
1. A method for producing a high-strength and high-toughness mullite-zirconia composite ceramic, which comprises sintering at a temperature of about 1,550 to 1,650° C. under conditions of 00° C./hr or less.
イト−ジルコニア複合セラミックスの製造方法において
、ベーマイトゾルとシリカゾルのＡｌ／Ｓｉのモル比が
約１．５〜２．８７であるもの。(5) In the method for producing a high-strength and high-toughness mullite-zirconia composite ceramic according to claim 4, the Al/Si molar ratio of the boehmite sol and the silica sol is about 1.5 to 2.87. .
イト−ジルコニア複合セラミックスの製造方法において
、ジルコニアゾルの添加量がＺｒＯ＿２換算で約３０体
積％以下であるもの。(6) In the method for manufacturing a high-strength and high-toughness mullite-zirconia composite ceramic according to claim 4, the amount of zirconia sol added is about 30% by volume or less in terms of ZrO_2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63224478A JPH0274560A (en) | 1988-09-09 | 1988-09-09 | Mullite-zirconia compound ceramics having high strength and toughness and production thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63224478A JPH0274560A (en) | 1988-09-09 | 1988-09-09 | Mullite-zirconia compound ceramics having high strength and toughness and production thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0274560A true JPH0274560A (en) | 1990-03-14 |
Family
ID=16814425
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63224478A Pending JPH0274560A (en) | 1988-09-09 | 1988-09-09 | Mullite-zirconia compound ceramics having high strength and toughness and production thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0274560A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0497942A (en) * | 1990-08-17 | 1992-03-30 | Chichibu Cement Co Ltd | Production of mullite-zirconia composite ceramics |
| CN101830717A (en) * | 2010-05-11 | 2010-09-15 | 浙江大学 | Zirconium sol reinforced corundum-mullite product and production method thereof |
-
1988
- 1988-09-09 JP JP63224478A patent/JPH0274560A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0497942A (en) * | 1990-08-17 | 1992-03-30 | Chichibu Cement Co Ltd | Production of mullite-zirconia composite ceramics |
| CN101830717A (en) * | 2010-05-11 | 2010-09-15 | 浙江大学 | Zirconium sol reinforced corundum-mullite product and production method thereof |
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