JP4997437B2 - Silicon carbide based porous molded body and method for producing the same - Google Patents
Silicon carbide based porous molded body and method for producing the same Download PDFInfo
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Description
本発明は、電子部品焼成用治具、排ガス浄化装置等の分離膜や半導体製造工程におけるフイルター材、或いは金属−セラミックス複合体として半導体製造工程でのウエハ等の熱処理装置やＣＶＤ装置における構造材や部品、触媒の担持体等として利用可能な、炭化珪素系多孔質成形体及びその製造方法に関する。 The present invention provides an electronic component firing jig, a separation membrane for an exhaust gas purification device, a filter material in a semiconductor manufacturing process, a heat treatment apparatus for wafers in a semiconductor manufacturing process as a metal-ceramic composite, and a structural material in a CVD apparatus, The present invention relates to a silicon carbide based porous molded body that can be used as a part, a catalyst support, and the like, and a method for producing the same.
近年、多孔質炭化珪素焼成体は、電子部品焼成用治具、排ガス浄化装置等の分離膜や半導体製造工程におけるフイルター材、或いは該多孔質炭化珪素焼成体の空隙にアルミニウムや珪素を含浸させてなる金属−セラミックス複合体として半導体製造工程でのウエハ等の熱処理装置やＣＶＤ装置における構造材や部品、触媒の担持体等として使用されている。 In recent years, a porous silicon carbide fired body has been obtained by impregnating aluminum or silicon into a separation membrane of an electronic component firing jig, an exhaust gas purification device, a filter material in a semiconductor manufacturing process, or a void of the porous silicon carbide fired body. The resulting metal-ceramic composite is used as a structural material or component in a heat treatment apparatus such as a wafer or a CVD apparatus in a semiconductor manufacturing process, a catalyst support, and the like.
従来、多孔質炭化珪素焼成体は、炭化珪素粉末に有機バインダと水とを添加し、混練後、成形し、アルゴンガス中で２２５０℃の高温下で約３時間焼成することにより製造される。また、グラファイトや有機高分子等の造孔剤を、焼成前の試料中に分散させた後に、熱処理して造孔剤を焼き飛ばすことにより、炭化珪素焼成体の多孔性を向上させることも知られている。
しかしながら、炭化珪素焼成体内に形成される細孔は、原料となる炭化珪素粉末の粒径や造孔剤の分子径よりも大きいものとなるので、微細孔を有する多孔質炭化珪素焼成体を製造することは、困難であった。
Conventionally, a porous silicon carbide fired body is manufactured by adding an organic binder and water to silicon carbide powder, kneading, molding, and firing in argon gas at a high temperature of 2250 ° C. for about 3 hours. It is also known that the porosity of a silicon carbide fired body is improved by dispersing a pore-forming agent such as graphite or organic polymer in a sample before firing and then heat-treating the pore-forming agent. It has been.
However, since the pores formed in the silicon carbide fired body are larger than the particle diameter of the silicon carbide powder as a raw material and the molecular diameter of the pore former, a porous silicon carbide fired body having fine pores is manufactured. It was difficult to do.
このような問題点を解決するために、炭化珪素焼成体の前駆体として有機珪素系高分子を用い、これに架橋剤を添加した後に熱処理することにより、多孔質炭化珪素焼成体を製造することが提案されている。（例えば、特許文献１〜３、非特許文献１〜７参照）
また、熱分解・焼成前前駆体に微粒子を分散させることにより、熱処理過程で有機珪素系高分子から発生する気体間の凝集を防止し、より小さい細孔を有する多孔質炭化珪素系焼成体を得る方法が提案されている。（特許文献４参照）
しかしながら、焼成体内に形成する細孔の径や、気孔率等を制御することは困難であり、また一度形成された細孔の径を制御することはできなかった。
Also, by dispersing fine particles in the precursor before pyrolysis and firing, aggregation between gases generated from the organosilicon polymer during the heat treatment process is prevented, and a porous silicon carbide fired body having smaller pores is obtained. A method of obtaining has been proposed. (See Patent Document 4)
However, it is difficult to control the diameter of the pores formed in the fired body, the porosity, and the like, and the diameter of the pores once formed cannot be controlled.
したがって、本発明は特別な工程や添加剤等を必要とせずに、種々の仕様用途に応じて制御された細孔径や気孔率等を有する炭化珪素系多孔質成形体、及びその製造方法を提供することを目的とする。 Therefore, the present invention provides a silicon carbide based porous molded body having a controlled pore diameter, porosity, etc. according to various specification applications without requiring any special process or additive, and a method for producing the same. The purpose is to do.
本発明者等は、鋭意検討した結果、炭化珪素系多孔質成形体の表面に、ＳｉＣＯからなる層を形成することにより、制御された微細孔を有する炭化珪素系多孔質成形体が得られることを見出し、本発明を完成したものである。 As a result of intensive studies, the present inventors have obtained that a silicon carbide based porous molded body having controlled fine pores can be obtained by forming a layer made of SiCO on the surface of the silicon carbide based porous molded body. And the present invention has been completed.
すなわち、本発明は、次の構成１、２を採用するものである。
１．架橋剤を使用せずに、炭化珪素前駆体高分子を不活性気体中において４００℃以下で加熱して熱的に架橋した炭化珪素前駆体を形成し、該架橋前駆体を熱処理することにより得られた炭化珪素系多孔質体を４００〜８００℃で酸化し、多孔質体表面にＳｉＣＯからなる層を形成することを特徴とする細孔を制御したＳｉＣＯ表面層付き炭化珪素系多孔質体の製造方法
２．炭化珪素系多孔質体が膜状体であることを特徴とする１に記載のＳｉＣＯ表面層付き炭化珪素系多孔質体の製造方法。
That is, the present invention employs the following configurations 1 and 2 .
1. It is obtained by heating a silicon carbide precursor polymer in an inert gas at 400 ° C. or lower to form a thermally crosslinked silicon carbide precursor without using a crosslinking agent, and heat-treating the crosslinked precursor. and the silicon carbide porous body to oxidize at 400 to 800 ° C., the porous body SiCO surface layer with silicon carbide with controlled pores, wherein the benzalkonium to form a layer made of SiCO the surface porous body 1. Manufacturing method 2 Method for producing a SiCO surface layer with silicon carbide-based porous body according to 1, wherein the silicon carbide based porous material is a membrane-like body.
本発明において、炭化珪素前駆体高分子とは、主にSiとCからなる主鎖を持ち、Si-H結合、C-H結合、Si-CH3結合等Si及びCそしてHからなる側鎖を持つ高分子であり、且つ、熱分解をすることで炭化珪素系成形体に変換可能な高分子のことを指す。但し、主鎖や側鎖を構成する元素をSi、C、Hのみに限定するものではなく、また、SiとCとHのすべての元素を保持している高分子に限定するものでもない。Si、C、H以外に、主鎖や側鎖にB(ホウ素)やN（窒素）等他の元素を含む高分子も含む。また、Al(アルミナ)やＺr（ジルコニア）等の金属を含んでいても良い。好ましい炭化珪素前駆体高分子としては、例えば、ポリカルボシラン、ポリメチルシラン、ポリジメチルシラン及びポリカルボシラザン等を挙げることができる。
また、炭化珪素系多孔質成形体とは、主にSiとCとHからなる多孔質の構造物を指し、炭化珪素前駆体高分子を熱分解することで得られる多孔質構造物を指す。但し、構造物の組成を、SiとCとHのみに限定するものではなく、また、SiとCとHのすべての元素を保持している構造物に限定するものでもない。また、Si、C、H以外に、構造物中にB(ホウ素)やN（窒素）そしてAl（アルミナ）やZr（ジルコニア）等他の元素を含む構造物も含む。具体例としては、例えば、炭化珪素（SiC）や窒化珪素(Si3N4)などを挙げることができる。
In the present invention, the silicon carbide precursor polymer has a main chain mainly composed of Si and C, and has a high side chain composed of Si, C, and H, such as Si—H bond, CH bond, and Si—CH 3 bond. It refers to a polymer that is a molecule and can be converted into a silicon carbide-based molded body by thermal decomposition. However, the elements constituting the main chain and the side chain are not limited to Si, C, and H, and are not limited to polymers holding all elements of Si, C, and H. In addition to Si, C, and H, polymers containing other elements such as B (boron) and N (nitrogen) in the main chain and side chain are also included. Further, a metal such as Al (alumina) or Zr (zirconia) may be included. Preferred examples of the silicon carbide precursor polymer include polycarbosilane, polymethylsilane, polydimethylsilane, and polycarbosilazane.
Further, the silicon carbide based porous molded body refers to a porous structure mainly composed of Si, C and H, and refers to a porous structure obtained by thermally decomposing a silicon carbide precursor polymer. However, the composition of the structure is not limited only to Si, C, and H, and is not limited to a structure that holds all elements of Si, C, and H. In addition to Si, C, and H, structures including other elements such as B (boron), N (nitrogen), Al (alumina), and Zr (zirconia) are also included in the structure. Specific examples include silicon carbide (SiC) and silicon nitride (Si 3 N 4 ).
本発明によれば、電子部品焼成用治具、排ガス浄化装置等の分離膜や半導体製造工程におけるフイルター材、或いは金属−セラミックス複合体として半導体製造工程でのウエハ等の熱処理装置やＣＶＤ装置における構造材や部品、触媒の担持体等として利用可能な炭化珪素系多孔質成形体を、種々の仕様用途に応じて制御された細孔径や気孔率等を有する多孔質成形体として、特別な工程や添加剤等を必要とせずに、低コストで製造することが可能となる。 According to the present invention, a structure for a heat treatment apparatus or a CVD apparatus for a wafer in a semiconductor manufacturing process as a separation film for an electronic component firing jig, an exhaust gas purification apparatus, a filter material in a semiconductor manufacturing process, or a metal-ceramic composite Silicon carbide-based porous molded bodies that can be used as materials, parts, catalyst supports, etc., as porous molded bodies having controlled pore diameters, porosity, etc. according to various specification applications, It is possible to manufacture at low cost without requiring an additive or the like.
本発明では、炭化珪素系多孔質成形体を４００〜８００℃で酸化し、成形体表面にＳｉＣＯからなる層を形成することにより、制御された細孔径や気孔率等を有するＳｉＣＯ表面層付き炭化珪素系多孔質成形体を製造することができる。
酸化処理される炭化珪素系多孔質成形体としては特に制限はなく、公知の炭化珪素系多孔質成形体はいずれも使用することができる。好ましい炭化珪素系多孔質成形体としては、例えば架橋剤を使用せずに、炭化珪素前駆体高分子を不活性気体中において３００℃以下で加熱して熱的に架橋したポリマー状の炭化珪素前駆体を形成し、該架橋前駆体を熱処理することにより製造された炭化珪素系多孔質成形体が挙げられる。
In the present invention, the silicon carbide based porous molded body is oxidized at 400 to 800 ° C., and a layer made of SiCO is formed on the surface of the molded body, so that carbonized with a SiCO surface layer having a controlled pore diameter, porosity, etc. A silicon-based porous molded body can be produced.
There is no restriction | limiting in particular as a silicon carbide type | system | group porous molded object oxidized, All the well-known silicon carbide type porous molded objects can be used. As a preferable silicon carbide based porous molded body, for example, without using a crosslinking agent, a polymeric silicon carbide precursor that is thermally crosslinked by heating a silicon carbide precursor polymer in an inert gas at 300 ° C. or lower. And a silicon carbide based porous molded body produced by heat-treating the cross-linking precursor.
原料となる好ましい炭化珪素前駆体高分子としては、例えば、ポリメチルシラン〔下記、一般式（１）〕、ポリジメチルシラン〔同（２）〕、ポリシリレンメチレン〔同（３）〕及びポリカルボシラン〔同（４）〕等が挙げられる。
上記各式において、ｎは１０以上の整数、通常は１０〜１００００程度、好ましくは１００〜１０００程度の整数を表す。
これらの炭化珪素前駆体高分子としては、数平均分子量（Gel permeation chromatography 示差屈折率／ポリスチレン換算）で、１０００以上のものを使用することが好ましい。数平均分子量は、次の式により求めた値を指す。
数平均分子量（Ｍｎ）＝系の全重量／系中の分子数＝Σ（Ｍｉ×Ｎｉ）／ΣＮｉ
（上式において、Ｍｉは分子量を表し、Ｎｉは分子量がＭｉの分子数を表す。）
In the above formulas, n represents an integer of 10 or more, usually about 10 to 10000, preferably about 100 to 1000.
As these silicon carbide precursor polymers, those having a number average molecular weight (Gel permeation chromatography differential refractive index / polystyrene conversion) of 1000 or more are preferably used. The number average molecular weight refers to a value determined by the following formula.
Number average molecular weight (Mn) = total weight of system / number of molecules in system = Σ (Mi × Ni) / ΣNi
(In the above formula, Mi represents the molecular weight, and Ni represents the number of molecules having a molecular weight of Mi.)
炭化珪素前駆体高分子は、架橋剤を使用せずに、窒素、アルゴン等の不活性気体中で４００℃以下の温度、好ましくは２００〜４００℃程度の温度で、１０時間以上、例えば１０〜２０時間程度加熱することによって熱的に架橋させて炭化珪素前駆体を形成する。ついで、該架橋前駆体を５００〜１３００℃程度、好ましくは６００〜８００℃程度の温度で、０時間以上、例えば１〜１０時間程度熱処理をすることによって、炭化珪素多孔質成形体を製造する。この熱架橋、及び熱処理は、連続した工程として行うことができる。 The silicon carbide precursor polymer is used in an inert gas such as nitrogen or argon at a temperature of 400 ° C. or lower, preferably at a temperature of about 200 to 400 ° C. for 10 hours or longer, for example 10 to 20 without using a crosslinking agent. The silicon carbide precursor is formed by thermal crosslinking by heating for about an hour. Next, the silicon carbide porous molded body is produced by heat-treating the cross-linking precursor at a temperature of about 500 to 1300 ° C., preferably about 600 to 800 ° C. for 0 hour or more, for example, about 1 to 10 hours. This thermal crosslinking and heat treatment can be performed as a continuous process.
本発明では、このようにして得られた炭化珪素系多孔質成形体や、従来の架橋剤等を使用して得られた炭化珪素系多孔質成形体を、さらに加熱、酸化して成形体表面にＳｉＣＯからなる層を形成することにより、制御された細孔径や気孔率等を有する多孔質成形体を製造する。
炭化珪素系多孔質成形体の加熱、酸化処理は、空気中等の酸化雰囲気下で、例えば４００〜８００℃、好ましくは５００〜７００℃程度の温度で、０時間以上、好ましくは１〜１０時間程度加熱することにより行うことができる。
In the present invention, the surface of the molded body is obtained by further heating and oxidizing the silicon carbide-based porous molded body thus obtained and the silicon carbide-based porous molded body obtained by using a conventional crosslinking agent or the like. A porous molded body having a controlled pore diameter, porosity and the like is manufactured by forming a layer made of SiCO.
The heating and oxidation treatment of the silicon carbide based porous molded body is carried out in an oxidizing atmosphere such as in the air, for example, at a temperature of 400 to 800 ° C., preferably about 500 to 700 ° C. for 0 hour or more, preferably about 1 to 10 hours. This can be done by heating.
この酸化処理により、炭化珪素系多孔質成形体の表面にＳｉＣＯからなる層が形成されるとともに、成形体中の細孔が収縮することにより、制御された細孔径や気孔率等を有する多孔質成形体が得られる。
このようなＳｉＣＯ表面層付き炭化珪素系多孔質成形体としては、例えば、平均細孔径０．２〜２ｎｍ、平均気孔率３０〜７０％、比表面積１０〜１０００ｍ２／ｇの成形体が挙げられるが、このような成形体は、従来の方法では得ることができないものであった。
As a result of this oxidation treatment, a layer made of SiCO is formed on the surface of the silicon carbide based porous molded body, and the pores in the molded body contract, so that the porous body has a controlled pore diameter, porosity, etc. A molded body is obtained.
Examples of such a silicon carbide-based porous molded body with a SiCO surface layer include a molded body having an average pore diameter of 0.2 to 2 nm, an average porosity of 30 to 70%, and a specific surface area of 10 to 1000 m 2 / g. However, such a molded body cannot be obtained by a conventional method.
本発明のＳｉＣＯ表面層付き炭化珪素多孔質成形体は、例えば、膜状、繊維状、塊状、チューブ状等種々の形状とすることができる。
多孔質成形体を製造する手順としては、例えば、アルミナ、セラミックスなどの基材上に、炭化珪素前駆体高分子であるポリカルボシランの有機溶媒溶液を塗布し、或いは該溶液に基材を浸漬もしくは接触させた後、基材上でポリカルボシランを２段階に加熱することによって、膜状の炭化珪素系多孔質成形体を製造する。ついで、この成形体を酸化雰囲気下で加熱、酸化することによって、制御された細孔径や気孔率等を有する膜状のＳｉＣＯ表面層付き炭化珪素多孔質成形体を得ることができる。
有機溶媒としては、例えばベンゼン、トルエン、キシレン等の炭化水素系溶媒や、テトラヒドロフラン等のエーテル系溶媒等を使用することができる。
The silicon carbide porous molded body with a SiCO surface layer of the present invention can have various shapes such as a film shape, a fiber shape, a lump shape, and a tube shape.
As a procedure for producing a porous molded body, for example, an organic solvent solution of polycarbosilane which is a silicon carbide precursor polymer is applied on a substrate such as alumina or ceramics, or the substrate is immersed in the solution. After the contact, the polycarbosilane is heated in two stages on the substrate to produce a film-like silicon carbide based porous molded body. Then, the molded body is heated and oxidized in an oxidizing atmosphere to obtain a silicon carbide porous molded body with a film-like SiCO surface layer having a controlled pore diameter, porosity, and the like.
As the organic solvent, for example, hydrocarbon solvents such as benzene, toluene and xylene, ether solvents such as tetrahydrofuran and the like can be used.
本発明によれば、例えば、平均細孔径０．２〜２ｎｍ、平均気孔率３０〜７０％、比表面積１０〜１０００ｍ２／ｇの、制御された細孔を有するＳｉＣＯ表面層付き炭化珪素多孔質成形体を、簡単な工程で安価に製造することができる。 According to the present invention, for example, a silicon carbide porous layer having a controlled pore having an average pore diameter of 0.2 to 2 nm, an average porosity of 30 to 70%, and a specific surface area of 10 to 1000 m 2 / g. A molded object can be manufactured at low cost by a simple process.
つぎに、実施例により本発明をさらに説明するが、以下の具体例は本発明を限定するものではない。
（実施例１）
炭化珪素前駆体高分子として、ポリカルボシラン（日本カーボン（株）社製：NIPUSI TYPE-S、数平均分子量1580）粉体5.4gをトルエン30mlに溶解し、この溶液を室温で一昼夜乾燥した。次にアルゴン気流中で昇温速度5℃/分で200℃に加熱し、この温度で1時間保持し、粉体中の水分等を揮発させた。その後、同じ昇温速度で653℃に加熱し、この温度に到達後、室温まで急冷し、粉状の炭化珪素系多孔質体を得た。得られた粉状の炭化珪素系多孔質成形体を、空気中（200ml/分）で昇温速度5℃/分で室温から1000℃まで酸化し、酸化処理過程における熱重量変化と気体発生挙動を、熱重量分析装置と質量分析装置を用い測定した。測定結果を図1に示す。
図1より、微分熱重量変化曲線は237℃で極大値を示した。また、酸化処理過程で、CO2とH2の発生が確認できた。それぞれ、355℃と440℃付近で最も多く揮発した。これにより、空気中で加熱することで、炭化珪素系多孔質成形体が酸化することが分かった。
EXAMPLES Next, the present invention will be further described with reference to examples, but the following specific examples are not intended to limit the present invention.
Example 1
As a silicon carbide precursor polymer, 5.4 g of polycarbosilane (manufactured by Nippon Carbon Co., Ltd .: NIPUSI TYPE-S, number average molecular weight 1580) powder was dissolved in 30 ml of toluene, and this solution was dried overnight at room temperature. Next, it was heated to 200 ° C. in an argon stream at a heating rate of 5 ° C./min, and kept at this temperature for 1 hour to volatilize moisture and the like in the powder. Then, it heated to 653 degreeC with the same temperature increase rate, and after reaching this temperature, it cooled rapidly to room temperature and obtained the powdery silicon carbide type porous body. The resulting powdery silicon carbide based porous compact is oxidized in air (200ml / min) from room temperature to 1000 ° C at a rate of temperature increase of 5 ° C / min. Thermogravimetric change and gas generation behavior during the oxidation process Was measured using a thermogravimetric analyzer and a mass spectrometer. The measurement results are shown in FIG.
From FIG. 1, the differential thermogravimetric change curve showed a maximum at 237 ° C. In addition, the generation of CO 2 and H 2 was confirmed during the oxidation process. Most volatilized around 355 ° C and 440 ° C, respectively. Thereby, it turned out that a silicon carbide type porous molded object oxidizes by heating in air.
（実施例２）
実施例1で得られた、酸化処理前の粉状炭化珪素系多孔質成形体を3つに分け、空気中（200ml/分）で昇温速度5℃/分で、239℃、355℃そして440℃までそれぞれ酸化し、それぞれの温度に到達後、直ちに急冷し、粉状の酸化済み炭化珪素系多孔質体を得た。酸化処理、及び酸化温度の違いが、炭化珪素系多孔質体内の官能基に与える影響を調べるため、得られた酸化済み炭化珪素系多孔質体の構造解析を、フーリエ変換赤外分光光度計を用い行なった。その結果を、図2に示した。
図2より、酸化温度の上昇に伴い、Si-CH2-Si、Si-H及びSi-CH3結合ピークが減少し、Si-O-Si結合ピークが増大した。この結果から、炭化珪素系多孔質成形体内の官能基（Si-CH2-Si、Si-H及びSi-CH3結合）が存在する部位と空気中の酸素が反応することで、炭化珪素系多孔質成形体の表面にSi-O-Si結合からなる部位が新たに生じることが示された。
(Example 2)
The powdered silicon carbide based porous molded body obtained in Example 1 before the oxidation treatment was divided into three parts, 239 ° C., 355 ° C., 239 ° C. Each was oxidized to 440 ° C., and after reaching each temperature, it was immediately cooled to obtain a powdered oxidized silicon carbide based porous material. In order to investigate the effect of differences in oxidation treatment and oxidation temperature on the functional groups in the silicon carbide porous body, structural analysis of the obtained oxidized silicon carbide porous body was conducted using a Fourier transform infrared spectrophotometer. Used. The results are shown in FIG.
From FIG. 2, the Si—CH 2 —Si, Si—H and Si—CH 3 bond peaks decreased and the Si—O—Si bond peak increased as the oxidation temperature increased. From this result, silicon carbide-based porous molded body reacts with oxygen in the air and the site where functional groups (Si-CH 2 -Si, Si-H and Si-CH 3 bonds) exist. It was shown that a new site consisting of Si-O-Si bonds was newly formed on the surface of the porous compact.
（実施例３）
実施例1で得られた、酸化処理前の粉状炭化珪素系多孔質成形体を3つに分け、空気中（200ml/分）で昇温速度5℃/分で、239℃、355℃そして440℃までそれぞれ酸化し、それぞれの温度に到達後、直ちに急冷し、粉状の酸化済み炭化珪素系多孔質体を得た。得られた粉状試料の窒素吸着測定を行い、酸化処理前の炭化珪素系多孔質成形体と比較した。その結果を図3に示す。
なお、当該窒素吸着測定は常法であり、次の手順で行なった。あらかじめ吸着していると考えられる空気、水分などを取り除くために、粉状の炭化珪素系多孔質体を吸着用ガラス管に入れて、真空中、300℃で5時間脱着前処理した。次に、この前処理済炭化珪素系多孔質体に、窒素ガスをその相対圧力を変化させながら吸着させて、77Kにおける吸着等温線を得た。
図3によれば、酸化温度の上昇に伴い、窒素吸着量が減少した。これは、酸化により炭化珪素系多孔質成形体内の細孔容積が減少したためと考えられた。
本実施例、及び実施例1〜2から得られた結果から、空気中で加熱することにより、炭化珪素系多孔質体内にSi-O-Si結合が形成され細孔容積が減少したと考えられた。
(Example 3)
The powdered silicon carbide based porous molded body obtained in Example 1 before the oxidation treatment was divided into three parts, 239 ° C., 355 ° C. and 239 ° C. in air (200 ml / min) at a temperature rising rate of 5 ° C./min. Each was oxidized to 440 ° C., and after reaching each temperature, it was immediately cooled to obtain a powdered oxidized silicon carbide based porous material. The obtained powder sample was subjected to nitrogen adsorption measurement and compared with a silicon carbide based porous molded body before oxidation treatment. The results are shown in FIG.
In addition, the said nitrogen adsorption measurement is a conventional method, and was performed in the following procedure. In order to remove air, moisture, etc. that are thought to be adsorbed in advance, a powdered silicon carbide based porous material was placed in an adsorption glass tube and pre-desorbed at 300 ° C. for 5 hours in a vacuum. Next, nitrogen gas was adsorbed on the pretreated silicon carbide based porous material while changing its relative pressure to obtain an adsorption isotherm at 77K.
According to FIG. 3, the amount of nitrogen adsorbed decreased as the oxidation temperature increased. This was thought to be because the pore volume in the silicon carbide based porous molded body was reduced by oxidation.
From the results obtained from this example and Examples 1 and 2, it is considered that the Si-O-Si bond was formed in the silicon carbide based porous body and the pore volume was reduced by heating in air. It was.
（実施例４）
実施例1で使用したポリカルボシランのトルエン溶液に、NOK社製のアルミナ基材(平均細孔径：150nm、平均気孔率：40％、内径：0.22cm、外径0.29cm、長さ：3cm)を浸漬後、取り出した支持体を、空気中で室温乾燥した。次にアルゴン気流中（200ml）で昇温速度5℃/分で200度に加熱し、この温度で1時間保持し、水分等を揮発させた。更に同じ昇温速度で700℃に加熱し、この温度で2時間保持することによりポリカルボシランを熱分解させた後に、降温速度5℃/分で室温まで降温しアルミナ基材上に膜状（膜厚：1.0μm程度）の炭化珪素系多孔質体を得た。得られた膜を、空気中（200ml/分）で昇温速度5℃/分で700℃に加熱し、この温度で2時間保持することにより、膜状の炭化珪素系多孔質成形体を酸化した後に、降温速度5℃/分で室温まで降温しアルミナ基材上に膜状（膜厚：1.0μm程度）の酸化済み炭化珪素系多孔質体を得た。得られた膜について、測定温度100℃でHe（2.60Å）、H2（2.89Å）、CO2（3.30Å）、O2（3.46Å）そしてN2（3.64Å)の透過速度を、タイムラグ法により測定した。これとは別に、酸化処理前の膜状炭化珪素系多孔質体について、測定温度100℃でHe、H2、CO2そしてN2の透過速度を、高真空タイムラグ法により測定した。上記の2種類の膜状試料から得られた透過速度測定結果を図4に示す。
Example 4
To the toluene solution of polycarbosilane used in Example 1, NOK alumina substrate (average pore diameter: 150 nm, average porosity: 40%, inner diameter: 0.22 cm, outer diameter 0.29 cm, length: 3 cm) After dipping, the taken out support was dried in air at room temperature. Next, it was heated to 200 ° C. in an argon stream (200 ml) at a heating rate of 5 ° C./min, and kept at this temperature for 1 hour to volatilize water and the like. Furthermore, after heating to 700 ° C at the same rate of temperature rise and holding at this temperature for 2 hours, the polycarbosilane was thermally decomposed, and then the temperature was lowered to room temperature at a rate of 5 ° C / min. A silicon carbide based porous material having a film thickness of about 1.0 μm was obtained. The obtained film was heated in air (200 ml / min) at a heating rate of 5 ° C / min to 700 ° C and held at this temperature for 2 hours to oxidize the film-like silicon carbide based porous molded body. Thereafter, the temperature was lowered to room temperature at a temperature lowering rate of 5 ° C./min to obtain an oxidized silicon carbide-based porous body in the form of a film (film thickness: about 1.0 μm) on an alumina substrate. With respect to the obtained film, the transmission rate of He (2.60 mm), H 2 (2.89 mm), CO 2 (3.30 mm), O 2 (3.46 mm) and N 2 (3.64 mm) at a measurement temperature of 100 ° C, time lag. Measured by the method. Separately from this, the permeation rate of He, H 2 , CO 2 and N 2 was measured by a high vacuum time lag method at a measurement temperature of 100 ° C. for the film-like silicon carbide based porous material before the oxidation treatment. The permeation rate measurement results obtained from the two types of membrane samples are shown in FIG.
酸化処理を施すことで、N2の透過速度は減少した。一方、He、H2の透過速度は増加した。酸化処理を施すことでN2の透過速度が減少したことは、実施例3で得られた結果と一致した。本実施例から、酸化処理を施すとことで、CO2(3.3Å)より小さい細孔の数が増える一方で、これより大きい径を持つ細孔の数は減少することが分かった。
N2が透過できる径を持つ細孔の減少は、酸化により細孔径が収縮したため引き起こされたと考えられる。
一方、HeやH2が透過できる径を持つ細孔の増加は、酸化によりフリーカーボン等がCO2となり揮発し、新たな細孔を生成したため引き起こされたと考えられる。
By performing the oxidation treatment, the permeation rate of N 2 decreased. On the other hand, the transmission rate of He and H 2 increased. The decrease in N 2 permeation rate due to the oxidation treatment was consistent with the result obtained in Example 3. From this example, it was found that the number of pores smaller than CO 2 (3.3 mm) increased while the number of pores having a larger diameter decreased by performing the oxidation treatment.
The decrease in pores with a diameter that allows N 2 to pass through is thought to be caused by the shrinkage of the pore diameter due to oxidation.
On the other hand, it is thought that the increase in the pores having a diameter through which He and H 2 can permeate was caused by the oxidation of free carbon and the like as CO 2 and volatilization due to oxidation, thereby generating new pores.
（実施例５）
実施例4と同様の手順で、2つの膜状（膜厚：1.0μm程度）の酸化済み炭化珪素系多孔質体を作製した。得られた膜について、測定温度100℃で、H2（2.89Å）そしてN2（3.64Å)の透過速度を、高真空タイムラグ法により測定した。これとは別に、酸化処理前の膜状炭化珪素系多孔質体についても、測定温度100℃でH2そしてN2の透過速度を、高真空タイムラグ法により測定した。それぞれの膜状試料から得られた透過速度測定結果を図5に示す。
酸化処理を施すことで、H2の透過速度は増加し、H2/N2選択性は向上した。これは、実施例4で得られた結果と同様に、酸化処理によって、HeやH2等の小さい分子のみが透過できる大きさの径を持つ細孔数の、N2が透過できる大きさの径を持つ細孔数に対する比が向上したためと考えられた。
(Example 5)
In the same procedure as in Example 4, two film-like (film thickness: about 1.0 μm) oxidized silicon carbide-based porous bodies were produced. With respect to the obtained film, the permeation rate of H 2 (2.89 mm) and N 2 (3.64 mm) was measured by a high vacuum time lag method at a measurement temperature of 100 ° C. Separately from this, the permeation rate of H 2 and N 2 was also measured by a high vacuum time lag method at a measurement temperature of 100 ° C. for the film-like silicon carbide based porous material before the oxidation treatment. FIG. 5 shows the permeation rate measurement results obtained from each film sample.
By performing the oxidation treatment, the permeation rate of H 2 increases, H 2 / N 2 selectivity was improved. This is similar to the result obtained in Example 4, because of the number of pores having a diameter that allows only small molecules such as He and H 2 to pass through the oxidation treatment, and the size that allows N 2 to pass through. This is thought to be because the ratio to the number of pores having a diameter was improved.
図6に酸化処理が炭化珪素系多孔質体に与える影響を模式的に示す。酸化温度が上昇するに従い、フリーカーボンが揮発し、HeやH2等の小さい分子のみが透過できる大きさの径を持つ細孔数が増加する一方で、元々あるN2が透過できる大きさの細孔内壁上に酸化層が形成されることによって、その数が減少すると考えられる。 FIG. 6 schematically shows the influence of the oxidation treatment on the silicon carbide based porous material. As the oxidation temperature rises, free carbon volatilizes and the number of pores with a size that allows only small molecules such as He and H 2 to pass through increases, while the original N 2 can pass through. It is considered that the number is reduced by forming an oxide layer on the inner wall of the pore.
以上の実施例から酸化による細孔径の収縮の程度や、フリーカーボン等の揮発による細孔数増加の程度は、酸化雰囲気や酸化温度、酸化時間によることから、これらを変化させることで、炭化珪素系多孔質成形体内の細孔径を任意に制御できることが示された。 From the above examples, the degree of shrinkage of pore diameter due to oxidation and the degree of increase in the number of pores due to volatilization of free carbon, etc. depend on the oxidizing atmosphere, oxidation temperature, and oxidation time. It was shown that the pore diameter in the system porous molded body can be arbitrarily controlled.
（実施例６）
炭化珪素前駆体高分子として、実施例1〜5で使用したポリカルボシランとは分子量の異なるポリカルボシラン（日本カーボン（株）社製：NIPUSI TYPE-A、数平均分子量1290）を用いた以外は実施例1と同じように処理をし、酸化処理過程における熱重量変化と気体発生挙動を、熱重量分析装置と質量分析装置を用い測定した。その結果、実施例1と同様に、CO2とH2の発生が確認でき、空気中で加熱することで、炭化珪素系多孔質成形体が酸化することが分かった。
(Example 6)
Except for using a polycarbosilane (manufactured by Nippon Carbon Co., Ltd .: NIPUSI TYPE-A, number average molecular weight 1290) having a different molecular weight from the polycarbosilane used in Examples 1 to 5 as the silicon carbide precursor polymer Treatment was performed in the same manner as in Example 1, and the thermogravimetric change and gas generation behavior during the oxidation treatment were measured using a thermogravimetric analyzer and a mass spectrometer. As a result, as in Example 1, the generation of CO 2 and H 2 could be confirmed, and it was found that the silicon carbide based porous molded body was oxidized by heating in air.
（実施例７）
実施例6で得られた、酸化処理前の粉状炭化珪素系多孔質成形体を3つに分け、実施例2と同様の手順で酸化した。得られた酸化済み炭化珪素系多孔質体の構造解析を、フーリエ変換赤外分光光度計を用い行なった。その結果、実施例2と同様に、酸化温度の上昇に伴い、Si-CH2-Si、Si-H及びSi-CH3結合ピークが減少し、Si-O-Si結合ピークが増大した。
(Example 7)
The powdery silicon carbide based porous molded body obtained in Example 6 before oxidation treatment was divided into three parts and oxidized in the same procedure as in Example 2. Structural analysis of the obtained oxidized silicon carbide based porous material was performed using a Fourier transform infrared spectrophotometer. As a result, as in Example 2, the Si—CH 2 —Si, Si—H, and Si—CH 3 bond peaks decreased and the Si—O—Si bond peak increased as the oxidation temperature increased.
（実施例８）
実施例6で得られた、酸化処理前の粉状炭化珪素系多孔質成形体を3つに分け、実施例3と同様の手順で酸化し粉状の酸化済み炭化珪素系多孔質体を得た。得られた粉状試料の窒素吸着測定を行い、酸化処理前の炭化珪素系多孔質成形体と比較した。その結果、実施例3と同様に、酸化温度の上昇に伴い、窒素吸着量が減少した。
(Example 8)
The powdered silicon carbide-based porous molded body before oxidation treatment obtained in Example 6 was divided into three, and oxidized in the same procedure as in Example 3 to obtain a powdered oxidized silicon carbide-based porous body It was. The obtained powder sample was subjected to nitrogen adsorption measurement and compared with a silicon carbide based porous molded body before oxidation treatment. As a result, as in Example 3, the nitrogen adsorption amount decreased as the oxidation temperature increased.
（実施例９）
実施例6で使用したポリカルボシランのトルエン溶液を用いたこと以外は、実施例4と同様の手順で、アルミナ基材上に膜状の酸化済み炭化珪素系多孔質体を得た。これと酸化処理前の膜状炭化珪素系多孔質体について、実施例4と同様に、測定温度100℃で種々の気体の透過速度を、高真空タイムラグ法により測定した。その結果、実施例4と同様に、酸化処理を施すことで、N2の透過速度は減少した。一方、He、H2の透過速度は増加した。
Example 9
A film-like oxidized silicon carbide based porous material was obtained on an alumina substrate in the same procedure as in Example 4 except that the toluene solution of polycarbosilane used in Example 6 was used. With respect to this and the film-like silicon carbide based porous material before the oxidation treatment, in the same manner as in Example 4, the permeation rate of various gases at a measurement temperature of 100 ° C. was measured by the high vacuum time lag method. As a result, as in Example 4, the permeation rate of N 2 was reduced by performing the oxidation treatment. On the other hand, the transmission rate of He and H 2 increased.
（実施例１０）
炭化珪素前駆体高分子として、実施例1〜9で使用したポリカルボシランとは分子量の異なるポリカルボシラン（日本カーボン（株）社製：NIPUSI TYPE-UH、数平均分子量1890）を用いた以外は実施例1と同じように処理をし、酸化処理過程における熱重量変化と気体発生挙動を、熱重量分析装置と質量分析装置を用い測定した。その結果、実施例1及び実施例6と同様に、CO2とH2の発生が確認でき、空気中で加熱することで、炭化珪素系多孔質成形体が酸化することが分かった。
(Example 10)
As the silicon carbide precursor polymer, except that polycarbosilane (Nippon Carbon Co., Ltd. product: NIPUSI TYPE-UH, number average molecular weight 1890) having a different molecular weight from the polycarbosilane used in Examples 1 to 9 was used. Treatment was performed in the same manner as in Example 1, and the thermogravimetric change and gas generation behavior during the oxidation treatment were measured using a thermogravimetric analyzer and a mass spectrometer. As a result, as in Example 1 and Example 6, generation of CO 2 and H 2 could be confirmed, and it was found that the silicon carbide based porous molded body was oxidized by heating in air.
（実施例１１）
実施例10で得られた、酸化処理前の粉状炭化珪素系多孔質成形体を3つに分け、実施例2と同様の手順で酸化した。得られた酸化済み炭化珪素系多孔質体の構造解析を、フーリエ変換赤外分光光度計を用い行なった。その結果、実施例2及び実施例7と同様に、酸化温度の上昇に伴い、Si-CH2-Si、Si-H及びSi-CH3結合ピークが減少し、Si-O-Si結合ピークが増大した。
(Example 11)
The powdery silicon carbide based porous molded body obtained in Example 10 before the oxidation treatment was divided into three parts and oxidized in the same procedure as in Example 2. Structural analysis of the obtained oxidized silicon carbide based porous material was performed using a Fourier transform infrared spectrophotometer. As a result, as in Example 2 and Example 7, as the oxidation temperature increased, Si—CH 2 —Si, Si—H and Si—CH 3 bond peaks decreased, and Si—O—Si bond peaks were reduced. Increased.
（実施例１２）
実施例10で得られた、酸化処理前の粉状炭化珪素系多孔質成形体を3つに分け、実施例3と同様の手順で酸化し粉状の酸化済み炭化珪素系多孔質体を得た。得られた粉状試料の窒素吸着測定を行い、酸化処理前の炭化珪素系多孔質成形体と比較した。その結果、実施例3及び実施例8と同様に、酸化温度の上昇に伴い、窒素吸着量が減少した。
(Example 12)
The powdered silicon carbide-based porous molded body before oxidation treatment obtained in Example 10 was divided into three, and oxidized in the same procedure as in Example 3 to obtain a powdered oxidized silicon carbide-based porous body It was. The obtained powder sample was subjected to nitrogen adsorption measurement and compared with a silicon carbide based porous molded body before oxidation treatment. As a result, as in Example 3 and Example 8, the amount of nitrogen adsorbed decreased as the oxidation temperature increased.
（実施例１３）
実施例10で使用したポリカルボシランのトルエン溶液を用いたこと以外は、実施例4と同様の手順で、アルミナ基材上に膜状の酸化済み炭化珪素系多孔質体を得た。これと酸化処理前の膜状炭化珪素系多孔質体について、実施例4と同様に、測定温度100℃で種々の気体の透過速度を、高真空タイムラグ法により測定した。その結果、実施例4及び実施例9と同様に、酸化処理を施すことで、N2の透過速度は減少した。一方、He、H2の透過速度は増加した。
(Example 13)
A film-like oxidized silicon carbide based porous material was obtained on an alumina substrate in the same procedure as in Example 4 except that the toluene solution of polycarbosilane used in Example 10 was used. With respect to this and the film-like silicon carbide based porous material before the oxidation treatment, in the same manner as in Example 4, the permeation rate of various gases at a measurement temperature of 100 ° C. was measured by the high vacuum time lag method. As a result, in the same manner as in Example 4 and Example 9, the N 2 permeation rate was reduced by performing the oxidation treatment. On the other hand, the transmission rate of He and H 2 increased.
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