JP2009013025A - Method of producing silicon carbide nanoparticle dispersion, silicon carbide nanoparticle dispersion and silicon carbide nanoparticle film - Google Patents

Method of producing silicon carbide nanoparticle dispersion, silicon carbide nanoparticle dispersion and silicon carbide nanoparticle film Download PDF

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JP2009013025A
JP2009013025A JP2007178413A JP2007178413A JP2009013025A JP 2009013025 A JP2009013025 A JP 2009013025A JP 2007178413 A JP2007178413 A JP 2007178413A JP 2007178413 A JP2007178413 A JP 2007178413A JP 2009013025 A JP2009013025 A JP 2009013025A
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silicon carbide
dispersion
oxide layer
nanoparticles
carbide nanoparticle
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JP5119769B2 (en
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Takashi Otsuka
剛史 大塚
Mikiro Konishi
幹郎 小西
Yoshiki Yoshioka
良樹 吉岡
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Sumitomo Osaka Cement Co Ltd
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<P>PROBLEM TO BE SOLVED: To provide a method of producing a silicon carbide nanoparticle dispersion in which dispersibility and dispersion stability are improved by suppressing the agglomeration of silicon carbide particles with each other, the silicon carbide nanparticle dispersion and a silicon carbide nano-particle film excellent in wear resistance, scratch resistance, heat resistance and hardness. <P>SOLUTION: The method of producing silicon carbide nanoparticle dispersion is carried out by oxidizing the surface of a silicon carbide nanoparticle 1 having agglomeration property to form a surface oxide layer 3, removing the surface oxide layer 3 and next, dispersing the easily dispersible silicon carbide nanoparticle 11 in a dispersant 4 after the removal of the surface oxide layer 3 of the silicon carbide nanoparticle 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、炭化ケイ素ナノ粒子分散液の製造方法及び炭化ケイ素ナノ粒子分散液並びに炭化ケイ素ナノ粒子膜に関し、さらに詳しくは、分散性及び分散安定性に優れた炭化ケイ素ナノ粒子分散液の製造方法及び炭化ケイ素ナノ粒子分散液、この炭化ケイ素ナノ粒子分散液を用いて形成され、軸受や摺動部材等の耐摩耗性被膜、耐擦傷性被膜、耐熱性被膜、硬質性被膜等に用いて好適な炭化ケイ素ナノ粒子膜に関するものである。   The present invention relates to a method for producing a silicon carbide nanoparticle dispersion, a silicon carbide nanoparticle dispersion, and a silicon carbide nanoparticle film, and more particularly, a method for producing a silicon carbide nanoparticle dispersion having excellent dispersibility and dispersion stability. And silicon carbide nanoparticle dispersion, formed using this silicon carbide nanoparticle dispersion, suitable for use in wear-resistant coatings such as bearings and sliding members, scratch-resistant coatings, heat-resistant coatings, hard coatings, etc. The present invention relates to a silicon carbide nanoparticle film.

炭化ケイ素(SiC)は、耐摩耗性等の機械的特性、耐熱性や熱伝導性等の熱的特性に優れ、しかも、化学的に極めて安定であり耐薬品性に優れていることから、研磨剤の他、耐火物、メカニカルシール、熱交換器等の構造材料として古くから利用されている。
これらの構造材料はいずれも人工的に合成された炭化ケイ素粉末が出発原料であり、炭化ケイ素粉末の工業的製造方法としては、アチソン法、シリカ還元法、シリコン炭化法等が知られているが、これらの方法は、微細化のために粉砕や解砕等のプロセスを必要とするため、平均粒子径はサブミクロン・オーダーまでが限界であり、したがって、平均粒子径がサブミクロン以上の粉末が主流であった。
Silicon carbide (SiC) has excellent mechanical properties such as wear resistance, thermal properties such as heat resistance and thermal conductivity, and is chemically stable and excellent in chemical resistance. In addition to chemicals, it has long been used as a structural material for refractories, mechanical seals, heat exchangers, and the like.
All of these structural materials are made from artificially synthesized silicon carbide powder, and as an industrial production method of silicon carbide powder, the Atchison method, silica reduction method, silicon carbonization method and the like are known. These methods require processes such as pulverization and pulverization for miniaturization, so the average particle size is limited to the order of submicron. Therefore, powders with an average particle size of submicron or more are required. It was mainstream.

一方、最近では、この炭化ケイ素粉末の新たな応用分野として、耐磨耗性被膜、耐擦傷性被膜、耐熱性被膜、硬質性被膜等を形成するための塗料や複合メッキ用のフィラーへの応用が検討されており、また、近年におけるナノテクノロジーブームの影響もあって、ナノサイズの炭化ケイ素粒子が大きな関心と注目を集めている。
ナノサイズの炭化ケイ素粒子を得る方法としては、非酸化雰囲気下にて、高温、高活性を有し、高速冷却プロセスの導入が容易な熱プラズマを利用した熱プラズマ法が挙げられる(例えば特許文献1参照)。この製造方法は、平均粒径5〜100nm程度の結晶性に優れた炭化ケイ素ナノ粒子を製造する方法として有用であり、高純度原料を選択することによって不純物の含有量が極めて少ない炭化ケイ素ナノ粒子を得ることが可能である。
また、有機ケイ素化合物、ケイ酸ゾル、ケイ酸ヒドロゲル等のケイ素を含む物質と、フェノール樹脂等の炭素を含む物質と、炭化ケイ素の粒成長を抑制するリチウム等の金属化合物とを含む混合物を非酸化性雰囲気下にて焼成して炭化ケイ素粒子を得るシリカ前駆体焼成法が挙げられる(例えば特許文献2参照)。この製造方法は、非常に微細かつ粗大粒子を含まない炭化ケイ素粉末が得られるという特徴を有する。
また、ナノサイズの炭化ケイ素粒子を溶媒中に分散させた炭化ケイ素分散液が提案されている(例えば特許文献3参照)。この分散液では、炭化ケイ素粒子の分散性を高めるために、炭化ケイ素粒子を酸化雰囲気下で酸化することによって表面酸化層を形成し、溶液への親和性を高めている。
On the other hand, recently, as a new application field of this silicon carbide powder, it is applied to paints for forming abrasion-resistant coatings, scratch-resistant coatings, heat-resistant coatings, hard coatings, and fillers for composite plating. In addition, under the influence of the recent nanotechnology boom, nano-sized silicon carbide particles have attracted a great deal of attention and attention.
Examples of a method for obtaining nano-sized silicon carbide particles include a thermal plasma method using thermal plasma that has high temperature and high activity in a non-oxidizing atmosphere and that can easily introduce a high-speed cooling process (for example, Patent Documents). 1). This production method is useful as a method for producing silicon carbide nanoparticles having an average particle size of about 5 to 100 nm and excellent in crystallinity, and silicon carbide nanoparticles having a very low impurity content by selecting a high-purity raw material. It is possible to obtain
In addition, a mixture containing a silicon-containing substance such as an organosilicon compound, a silicate sol, or a silicate hydrogel, a carbon-containing substance such as a phenol resin, and a metal compound such as lithium that suppresses the grain growth of silicon carbide is not contained. Examples thereof include a silica precursor firing method in which silicon carbide particles are obtained by firing in an oxidizing atmosphere (see, for example, Patent Document 2). This production method is characterized in that a silicon carbide powder that is very fine and free of coarse particles can be obtained.
Further, a silicon carbide dispersion liquid in which nano-sized silicon carbide particles are dispersed in a solvent has been proposed (see, for example, Patent Document 3). In this dispersion, in order to enhance the dispersibility of the silicon carbide particles, the surface oxide layer is formed by oxidizing the silicon carbide particles in an oxidizing atmosphere, thereby increasing the affinity for the solution.

このナノサイズの炭化ケイ素粒子を用いて耐磨耗性被膜、耐擦傷性被膜、耐熱性被膜、硬質性被膜等を形成する方法としては、上記の表面酸化層を形成したナノサイズの炭化ケイ素粒子を溶媒中に分散させた分散液を被処理物に塗布して塗膜を形成し、この塗膜を熱処理して炭化系素粒子膜を形成する方法がある。
また、セラミックス薄膜としては、炭化ケイ素等を主成分とする薄膜中のセラミックス成分の微細結晶粒子の存在割合が表層に向かって傾斜的に増大しているセラミックス薄膜が提案されている(例えば特許文献4参照)。
また、プラスチックの摺動部材としては、炭化ケイ素等の無機粒子を各種樹脂材料に混入させた組成物が提案されている(例えば特許文献5参照)。
また、炭化ケイ素薄膜を被処理物に直接形成する方法としては、被処理物の表面に、各種CVD法、スパッタリング法、各種MBE法等を用いて炭化ケイ素薄膜を形成する方法が提案されている(例えば特許文献6、7参照)。
特許第3023435号公報 特開昭63−95105号公報 特開平7−330543号公報 特開2004−67480号公報 特開平8−239682号公報 特開2006−147866号公報 特許第3131773号公報
As a method of forming an abrasion-resistant coating, an abrasion-resistant coating, a heat-resistant coating, a hard coating, etc. using the nano-sized silicon carbide particles, the nano-sized silicon carbide particles having the surface oxide layer formed thereon are used. There is a method of forming a coating film by applying a dispersion liquid in which a solvent is dispersed in a solvent to form a coating film, and heat-treating the coating film to form a carbonized elementary particle film.
In addition, as a ceramic thin film, a ceramic thin film in which the ratio of the fine crystal particles of the ceramic component in the thin film mainly composed of silicon carbide or the like is gradually increasing toward the surface layer has been proposed (for example, Patent Documents). 4).
Moreover, as a plastic sliding member, a composition in which inorganic particles such as silicon carbide are mixed in various resin materials has been proposed (see, for example, Patent Document 5).
In addition, as a method for directly forming a silicon carbide thin film on an object to be processed, a method for forming a silicon carbide thin film on the surface of the object to be processed by using various CVD methods, sputtering methods, various MBE methods and the like has been proposed. (For example, refer to Patent Documents 6 and 7).
Japanese Patent No. 3023435 JP 63-95105 A JP-A-7-330543 JP 2004-67480 A JP-A-8-239682 JP 2006-147866 A Japanese Patent No. 3131773

ところで、従来のナノサイズの炭化ケイ素粒子を得る方法では、得られた炭化ケイ素ナノ粒子は、アルミナやシリカ等の酸化物ナノ粒子と比較して粒子同士の凝集力が強く、炭化ケイ素ナノ粒子を製造することができても、このナノ粒子を用いて分散粒径が100nm以下の分散液を作製することが困難であるという問題点があった。
また、得られた炭化ケイ素ナノ粒子は、副生成物としてフリーカーボンなどの炭素質を数重量%程度含有しており、これら炭化ケイ素ナノ粒子と炭素質を同時に溶液中に分散させることが難しく、分散安定性は必ずしも十分ではないという問題点があった。
By the way, in the conventional method of obtaining nano-sized silicon carbide particles, the obtained silicon carbide nanoparticles have a stronger cohesion force between the particles than oxide nanoparticles such as alumina and silica, and silicon carbide nanoparticles are used. Even if it can be produced, there is a problem that it is difficult to produce a dispersion having a dispersed particle size of 100 nm or less using these nanoparticles.
Moreover, the obtained silicon carbide nanoparticles contain about several weight% of carbonaceous material such as free carbon as a by-product, and it is difficult to simultaneously disperse these silicon carbide nanoparticles and carbonaceous material in a solution, There was a problem that dispersion stability was not always sufficient.

また、従来の炭化ケイ素分散液では、炭化ケイ素粒子を酸化雰囲気下で表面酸化することにより溶液への親和性を高めているが、炭化ケイ素粒子を酸化雰囲気下にて熱処理した際に、表面酸化層が溶着を起こし、炭化ケイ素ナノ粒子同士が凝集してしまい、その結果、ナノ粒子の溶液中への分散化が困難になるという問題点があった。   In addition, in the conventional silicon carbide dispersion, the affinity to the solution is enhanced by surface oxidation of the silicon carbide particles in an oxidizing atmosphere. However, when the silicon carbide particles are heat-treated in the oxidizing atmosphere, the surface oxidation is performed. The layers cause welding, and the silicon carbide nanoparticles are aggregated. As a result, there is a problem that it is difficult to disperse the nanoparticles in the solution.

また、従来の炭化系素粒子膜を形成する方法では、炭化ケイ素粒子に形成された表面酸化層が酸化物の脆弱層であるために、塗膜の耐摩耗性、耐擦傷性及び表面硬さが低下するという問題点があった。
また、従来のセラミックス薄膜では、有機珪素重合体を熱処理にて無機化する際の熱処理温度が基板の耐熱温度に限定されてしまい、その結果、良好な結晶性を有するセラミックス薄膜、すなわち、耐摩耗性、耐擦傷性、表面硬度に優れた薄膜を得ることが困難であり、また、最表層の微粒子が摺動に際して脱粒した場合、耐摩耗性、耐擦傷性、硬度が急激に劣化するという問題点があった。
Further, in the conventional method for forming a carbonized elementary particle film, since the surface oxide layer formed on the silicon carbide particles is an oxide brittle layer, the wear resistance, scratch resistance and surface hardness of the coating film are reduced. There has been a problem of lowering.
Further, in the conventional ceramic thin film, the heat treatment temperature when mineralizing the organosilicon polymer by heat treatment is limited to the heat resistant temperature of the substrate, and as a result, the ceramic thin film having good crystallinity, that is, wear resistance It is difficult to obtain a thin film with excellent durability, scratch resistance, and surface hardness, and when the outermost layer particles fall off during sliding, the wear resistance, scratch resistance, and hardness deteriorate rapidly. There was a point.

また、従来のプラスチックの摺動部材では、炭化ケイ素等の無機粒子を樹脂材料へ混練するプロセスにおけるコスト高の問題点や、微粒子の均質な混錬や分散が困難であるという問題点があった。
また、従来の炭化ケイ素薄膜を直接形成する方法では、高品位な炭化ケイ素薄膜を得ることが可能であるが、被処理物を600℃〜1200℃以上の高温に加熱する必要があるため、被処理物に制約を受けるという問題点があった。また、非常に高価な製造設備が必要であり、しかも成膜速度が遅いことから、製造コストが高くなるという問題点もあった。
In addition, the conventional plastic sliding member has a problem of high cost in a process of kneading inorganic particles such as silicon carbide into a resin material, and it is difficult to uniformly knead and disperse fine particles. .
In addition, in the conventional method of directly forming a silicon carbide thin film, it is possible to obtain a high-quality silicon carbide thin film. However, since the object to be processed must be heated to a high temperature of 600 ° C. to 1200 ° C. or higher, There was a problem of being restricted by the processed material. In addition, a very expensive manufacturing facility is required, and the film forming speed is slow, which increases the manufacturing cost.

本発明は、上記の課題を解決するためになされたものであって、炭化ケイ素ナノ粒子同士の凝集を抑制することにより分散性及び分散安定性を向上させることが可能な炭化ケイ素ナノ粒子分散液の製造方法及び炭化ケイ素ナノ粒子分散液、この炭化ケイ素ナノ粒子分散液を用いて得られた耐摩耗性、耐擦傷性、耐熱性、硬質性に優れた炭化ケイ素ナノ粒子膜を提供することを目的とする。   The present invention has been made to solve the above-described problem, and is a silicon carbide nanoparticle dispersion that can improve dispersibility and dispersion stability by suppressing aggregation of silicon carbide nanoparticles. And a silicon carbide nanoparticle dispersion liquid, and a silicon carbide nanoparticle film excellent in wear resistance, scratch resistance, heat resistance, and hardness obtained by using the silicon carbide nanoparticle dispersion liquid. Objective.

本発明者等は、上記の課題を解決するために鋭意検討を重ねた結果、炭化ケイ素ナノ粒子の表面に酸化処理を施して表面酸化層を形成した後に、この炭化ケイ素ナノ粒子の表面酸化層を除去すれば、この表面酸化層が除去された炭化ケイ素ナノ粒子が凝集することなく分散媒中に分散され、しかもこの分散性が長期に亘って維持されることを見出し、本発明を完成するに至った。   As a result of intensive studies to solve the above problems, the present inventors have formed a surface oxide layer by subjecting the surface of the silicon carbide nanoparticles to oxidation treatment, and then the surface oxide layer of the silicon carbide nanoparticles. By removing the surface oxide layer, the silicon carbide nanoparticles from which the surface oxide layer has been removed are dispersed in the dispersion medium without agglomeration, and the dispersibility is maintained over a long period of time, thereby completing the present invention. It came to.

すなわち、本発明の炭化ケイ素ナノ粒子分散液の製造方法は、炭化ケイ素ナノ粒子の表面に酸化処理を施して表面酸化層を形成し、次いで、この炭化ケイ素ナノ粒子の表面酸化層を除去し、次いで、この表面酸化層が除去された炭化ケイ素ナノ粒子を分散媒中に分散させることを特徴とする。   That is, in the method for producing a silicon carbide nanoparticle dispersion of the present invention, the surface of the silicon carbide nanoparticles is oxidized to form a surface oxide layer, and then the surface oxide layer of the silicon carbide nanoparticles is removed, Next, the silicon carbide nanoparticles from which the surface oxide layer has been removed are dispersed in a dispersion medium.

前記炭化ケイ素ナノ粒子の一次粒子の平均粒子径は、5nm以上かつ500nm以下であることが好ましい。
前記酸化処理は、酸化性雰囲気下、300℃以上かつ800℃以下の温度範囲での熱処理であることが好ましい。
前記炭化ケイ素ナノ粒子の表面酸化層を、還元性雰囲気下または不活性雰囲気下にて熱処理し、前記表面酸化層を除去することが好ましい。
前記炭化ケイ素ナノ粒子の表面酸化層を、フッ酸、フッ化アンモニウム、硝酸の群から選択された1種または2種以上を含む溶液を用いて溶解し、前記表面酸化層を除去することが好ましい。
前記表面酸化層が除去された炭化ケイ素ナノ粒子を、湿式法により前記分散媒中に分散させることが好ましい。
The average particle diameter of primary particles of the silicon carbide nanoparticles is preferably 5 nm or more and 500 nm or less.
The oxidation treatment is preferably a heat treatment in a temperature range of 300 ° C. or higher and 800 ° C. or lower in an oxidizing atmosphere.
The surface oxide layer of the silicon carbide nanoparticles is preferably heat-treated in a reducing atmosphere or an inert atmosphere to remove the surface oxide layer.
Preferably, the surface oxide layer of the silicon carbide nanoparticles is dissolved using a solution containing one or more selected from the group of hydrofluoric acid, ammonium fluoride, and nitric acid, and the surface oxide layer is removed. .
The silicon carbide nanoparticles from which the surface oxide layer has been removed are preferably dispersed in the dispersion medium by a wet method.

本発明の炭化ケイ素ナノ粒子分散液は、本発明の炭化ケイ素ナノ粒子分散液の製造方法により得られたことを特徴とする。   The silicon carbide nanoparticle dispersion of the present invention is obtained by the method for producing a silicon carbide nanoparticle dispersion of the present invention.

本発明の炭化ケイ素ナノ粒子膜は、本発明の炭化ケイ素ナノ粒子分散液を用いて形成された塗膜を、熱処理してなることを特徴とする。   The silicon carbide nanoparticle film of the present invention is obtained by heat-treating a coating film formed using the silicon carbide nanoparticle dispersion of the present invention.

本発明の炭化ケイ素ナノ粒子分散液の製造方法によれば、炭化ケイ素ナノ粒子の表面に酸化処理を施して表面酸化層を形成し、次いで、この炭化ケイ素ナノ粒子の表面酸化層を除去し、次いで、この表面酸化層が除去された炭化ケイ素ナノ粒子を分散媒中に分散させるので、炭化ケイ素ナノ粒子同士の凝集を抑制することで分散性及び分散安定性が向上した炭化ケイ素ナノ粒子分散液を作製することができる。   According to the method for producing a silicon carbide nanoparticle dispersion of the present invention, the surface of the silicon carbide nanoparticles is oxidized to form a surface oxide layer, and then the surface oxide layer of the silicon carbide nanoparticles is removed, Next, since the silicon carbide nanoparticles from which the surface oxide layer has been removed are dispersed in the dispersion medium, the silicon carbide nanoparticle dispersion with improved dispersibility and dispersion stability by suppressing aggregation of the silicon carbide nanoparticles. Can be produced.

本発明の炭化ケイ素ナノ粒子分散液によれば、本発明の炭化ケイ素ナノ粒子分散液の製造方法により得られたので、炭化ケイ素ナノ粒子同士の凝集がなく、この炭化ケイ素ナノ粒子の分散性及び分散安定性に優れた分散液を得ることができる。その結果、分散性及び分散安定性に優れた炭化ケイ素ナノ粒子分散液を提供することができる。   According to the silicon carbide nanoparticle dispersion of the present invention, since the silicon carbide nanoparticle dispersion was obtained by the method for producing a silicon carbide nanoparticle dispersion of the present invention, there was no aggregation between the silicon carbide nanoparticles, and the dispersibility of the silicon carbide nanoparticles and A dispersion having excellent dispersion stability can be obtained. As a result, a silicon carbide nanoparticle dispersion having excellent dispersibility and dispersion stability can be provided.

本発明の炭化ケイ素ナノ粒子膜によれば、本発明の炭化ケイ素ナノ粒子分散液を用いて形成された塗膜を熱処理したので、炭化ケイ素ナノ粒子同士の凝集がなく、結晶性及び膜の均一性に優れている。   According to the silicon carbide nanoparticle film of the present invention, since the coating film formed using the silicon carbide nanoparticle dispersion of the present invention was heat-treated, there was no aggregation between the silicon carbide nanoparticles, and the crystallinity and the film were uniform. Excellent in properties.

本発明の炭化ケイ素ナノ粒子分散液の製造方法及び炭化ケイ素ナノ粒子分散液並びに炭化ケイ素ナノ粒子膜を実施するための最良の形態について説明する。
なお、この形態は、発明の趣旨をより良く理解させるために具体的に説明するものであり、特に指定のない限り、本発明を限定するものではない。
The manufacturing method of the silicon carbide nanoparticle dispersion of the present invention, the silicon carbide nanoparticle dispersion, and the best mode for carrying out the silicon carbide nanoparticle film will be described.
This embodiment is specifically described for better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

「炭化ケイ素ナノ粒子分散液の製造方法」
本発明の炭化ケイ素ナノ粒子分散液の製造方法は、炭化ケイ素ナノ粒子の表面に酸化処理を施して表面酸化層を形成し、次いで、この炭化ケイ素ナノ粒子の表面酸化層を除去し、次いで、この表面酸化層が除去された炭化ケイ素ナノ粒子を分散媒中に分散させる方法である。
“Production Method of Silicon Carbide Nanoparticle Dispersion”
In the method for producing a silicon carbide nanoparticle dispersion of the present invention, the surface of the silicon carbide nanoparticles is oxidized to form a surface oxide layer, and then the surface oxide layer of the silicon carbide nanoparticles is removed, In this method, the silicon carbide nanoparticles from which the surface oxide layer has been removed are dispersed in a dispersion medium.

この炭化ケイ素ナノ粒子分散液の製造方法について、図1を参照しつつ詳細に説明する。
この酸化処理の対象となる炭化ケイ素ナノ粒子の一次粒子の平均粒径は、5〜500nmであることが好ましく、より好ましくは10〜200nm、さらに好ましくは15〜100nmである。
ここで、炭化ケイ素ナノ粒子の一次粒子の平均粒径を5〜500nmと限定した理由は、平均粒径が5nmより小さいと、炭化ケイ素の結晶性が劣ったものとなり、この粒子を用いて粒子膜を作製した際に、膜の耐摩耗性及び硬質性が低下するからであり、一方、平均粒径が500nmを超えると、この粒子を分散液に分散させた際に分散液中における炭化ケイ素ナノ粒子の凝集傾向が非常に強くなり、均一な膜形成が困難となるからであり、さらに、この分散液を用いて膜を形成すると、形成された膜の表面粗さが増大し、その結果、摺動することによる炭化ケイ素ナノ粒子の脱離が発生し、膜の摩擦抵抗が増大するからである。
A method for producing the silicon carbide nanoparticle dispersion will be described in detail with reference to FIG.
The average particle diameter of primary particles of the silicon carbide nanoparticles to be oxidized is preferably 5 to 500 nm, more preferably 10 to 200 nm, still more preferably 15 to 100 nm.
Here, the reason why the average particle size of the primary particles of silicon carbide nanoparticles is limited to 5 to 500 nm is that when the average particle size is smaller than 5 nm, the crystallinity of silicon carbide is inferior. This is because when the film is produced, the wear resistance and hardness of the film are lowered. On the other hand, when the average particle diameter exceeds 500 nm, the silicon carbide in the dispersion liquid is dispersed when the particles are dispersed in the dispersion liquid. This is because the tendency of nanoparticles to agglomerate becomes very strong and it is difficult to form a uniform film. Further, when a film is formed using this dispersion, the surface roughness of the formed film increases, and as a result. This is because the silicon carbide nanoparticles are detached by sliding, and the frictional resistance of the film is increased.

この炭化ケイ素ナノ粒子は、熱プラズマ法あるいはシリカ前駆体焼成法により得られるが、得られた炭化ケイ素ナノ粒子は凝集性を有する粒子であるから、図1(a)に示すように、この凝集性を有する炭化ケイ素ナノ粒子1の表面あるいはこれらの間に、有機化合物の分解生成物であるフリーカーボン等の炭素質2が存在している。   The silicon carbide nanoparticles can be obtained by a thermal plasma method or a silica precursor firing method. Since the obtained silicon carbide nanoparticles are particles having aggregating properties, as shown in FIG. A carbonaceous material 2 such as free carbon, which is a decomposition product of an organic compound, is present on the surface of the silicon carbide nanoparticles 1 having the property or between them.

このように、炭化ケイ素ナノ粒子の表面にフリーカーボン等の炭素質が存在していた場合、この炭化ケイ素ナノ粒子を分散液中に分散した際に分散性不良を引き起こし、均一分散を妨げる。そこで、フリーカーボン等の炭素質を除去するために、この炭化ケイ素ナノ粒子の表面に酸化処理を施し、このフリーカーボン等の炭素質を反応ガス化(CO、HO等)して除去する。 As described above, when carbonaceous material such as free carbon is present on the surface of the silicon carbide nanoparticles, when the silicon carbide nanoparticles are dispersed in the dispersion liquid, poor dispersibility is caused and uniform dispersion is prevented. Therefore, in order to remove carbonaceous substances such as free carbon, the surface of the silicon carbide nanoparticles is subjected to oxidation treatment, and the carbonaceous substances such as free carbon are removed by reaction gasification (CO 2 , H 2 O, etc.). To do.

この酸化処理は、酸化性雰囲気下、300℃以上かつ800℃以下の温度、より好ましくは400℃以上かつ700℃以下の温度、さらに好ましくは500℃以上かつ600℃以下の温度にて熱処理することが好ましい。
この酸化性雰囲気としては、酸素または水分を含有する雰囲気であれば良く、経済性を考慮すると大気中の雰囲気が最も好ましい。
ここで、酸化処理の温度を300℃以上かつ800℃以下と限定した理由は、300℃未満では、酸化が不十分で、炭化ケイ素ナノ粒子を作製する際に生じる副生成物であるフリーカーボン等の炭素質を燃焼除去することができないからであり、一方、800℃を超えると、炭化ケイ素ナノ粒子が酸化され過ぎてしまい、後工程である表面酸化層を除去する際にロスが大きくなるからである。
This oxidation treatment is performed in an oxidizing atmosphere at a temperature of 300 ° C. or higher and 800 ° C. or lower, more preferably 400 ° C. or higher and 700 ° C. or lower, and even more preferably 500 ° C. or higher and 600 ° C. or lower. Is preferred.
The oxidizing atmosphere may be an atmosphere containing oxygen or moisture, and the atmosphere in the air is most preferable in consideration of economy.
Here, the reason why the temperature of the oxidation treatment is limited to 300 ° C. or more and 800 ° C. or less is that if it is less than 300 ° C., oxidation is insufficient and free carbon that is a by-product generated when producing silicon carbide nanoparticles, etc. On the other hand, when the temperature exceeds 800 ° C., silicon carbide nanoparticles are excessively oxidized, and loss is increased when removing the surface oxide layer, which is a subsequent process. It is.

この酸化処理の結果、図1(b)に示すように、炭化ケイ素ナノ粒子1は、その表面にシリカからなる表面酸化層3が形成された易分散性の炭化ケイ素ナノ粒子11となる。
この炭化ケイ素ナノ粒子11の表面に形成された表面酸化層3は、次のような問題を生じさせる。
a.これらの炭化ケイ素ナノ粒子の表面酸化層同士が融着し、炭化ケイ素ナノ粒子が凝集する。
b.表面酸化層が脆弱なことから、炭化ケイ素ナノ粒子が本来有している耐摩耗性、耐擦傷性、表面硬さ(高硬度)等の諸特性が劣化する。さらに、炭化ケイ素ナノ粒子が脱落することにより、膜自体の特性が大幅に低下する。
そこで、この炭化ケイ素ナノ粒子の表面に形成された表面酸化層を除去する。
As a result of this oxidation treatment, the silicon carbide nanoparticles 1 become easily dispersible silicon carbide nanoparticles 11 having a surface oxide layer 3 made of silica formed on the surface thereof, as shown in FIG.
The surface oxide layer 3 formed on the surface of the silicon carbide nanoparticles 11 causes the following problems.
a. The surface oxide layers of these silicon carbide nanoparticles are fused together, and the silicon carbide nanoparticles are aggregated.
b. Since the surface oxide layer is fragile, various characteristics such as wear resistance, scratch resistance, surface hardness (high hardness) and the like inherent to the silicon carbide nanoparticles are deteriorated. Furthermore, the silicon carbide nanoparticles fall off, and the characteristics of the film itself are greatly deteriorated.
Therefore, the surface oxide layer formed on the surface of the silicon carbide nanoparticles is removed.

この表面酸化層の除去には、次の(1)、(2)のいずれかの方法が用いられる。
(1)熱処理による方法
炭化ケイ素ナノ粒子の表面酸化層を、還元性雰囲気下または不活性雰囲気下にて熱処理し、この表面酸化層を除去する。
この還元性雰囲気としては、例えば、水素、一酸化炭素などの単体ガス、あるいはメタン、エタンなどの炭化水素ガスが好適に用いられ、これらのガスのうち1種または2種以上を選択して用いることができる。
また、不活性雰囲気としては、例えば、窒素などの不活性ガス、アルゴン、ネオン、キセノンなどの希ガス等が好適に用いられる。
For the removal of the surface oxide layer, one of the following methods (1) and (2) is used.
(1) Method by heat treatment The surface oxide layer of silicon carbide nanoparticles is heat-treated in a reducing atmosphere or an inert atmosphere, and the surface oxide layer is removed.
As the reducing atmosphere, for example, a simple gas such as hydrogen or carbon monoxide, or a hydrocarbon gas such as methane or ethane is preferably used, and one or more of these gases are selected and used. be able to.
As the inert atmosphere, for example, an inert gas such as nitrogen, or a rare gas such as argon, neon, or xenon is preferably used.

この熱処理の温度としては、表面酸化層を除去することができる温度であればよく、1500℃以上かつ2000℃以下が好ましく、より好ましくは1700℃以上かつ1900℃以下である。
ここで熱処理の温度を1500℃以上かつ2000℃以下と限定した理由は、1500℃未満では、酸化物の昇華が不十分で、表面酸化層を完全に除去することができないからであり、一方、2000℃を超えると、表面酸化層が完全に除去されるのみならず、炭化ケイ素ナノ粒子自体が焼結してしまい、分散性に優れた炭化ケイ素ナノ粒子が得られなくなるからである。
The temperature of this heat treatment may be any temperature at which the surface oxide layer can be removed, and is preferably 1500 ° C. or higher and 2000 ° C. or lower, more preferably 1700 ° C. or higher and 1900 ° C. or lower.
The reason why the temperature of the heat treatment is limited to 1500 ° C. or more and 2000 ° C. or less is that if the temperature is less than 1500 ° C., the oxide sublimation is insufficient and the surface oxide layer cannot be completely removed. When the temperature exceeds 2000 ° C., not only the surface oxide layer is completely removed, but also the silicon carbide nanoparticles themselves are sintered, and silicon carbide nanoparticles having excellent dispersibility cannot be obtained.

この還元性雰囲気または不活性雰囲気の熱処理により、炭化ケイ素ナノ粒子の表面に形成された表面酸化層(シリカ層)を一酸化ケイ素ガス(SiO)として、分解除去することが可能である。   By this heat treatment in a reducing atmosphere or an inert atmosphere, the surface oxide layer (silica layer) formed on the surface of the silicon carbide nanoparticles can be decomposed and removed as silicon monoxide gas (SiO).

(2)溶解による方法
炭化ケイ素ナノ粒子の表面酸化層を、フッ酸、フッ化アンモニウム、硝酸の群から選択された1種または2種以上を含む溶液を用いて溶解し、表面酸化層を除去する。
この方法では、表面酸化層が形成された炭化ケイ素ナノ粒子を、フッ酸、フッ化アンモニウム、硝酸の群から選択された1種または2種以上を含む溶液に浸漬させることにより、炭化珪素ナノ粒子の表面に形成された表面酸化層(シリカ層)を溶解除去することが可能である。
(2) Method by dissolution The surface oxide layer of silicon carbide nanoparticles is dissolved using a solution containing one or more selected from the group of hydrofluoric acid, ammonium fluoride, and nitric acid, and the surface oxide layer is removed. To do.
In this method, silicon carbide nanoparticles having a surface oxide layer formed are immersed in a solution containing one or more selected from the group consisting of hydrofluoric acid, ammonium fluoride, and nitric acid, thereby forming silicon carbide nanoparticles. It is possible to dissolve and remove the surface oxide layer (silica layer) formed on the surface.

これらの方法では、表面酸化層の除去に加熱を伴わないので、炭化ケイ素ナノ粒子の凝集を抑制することができる。その結果、図1(c)に示すように、高純度かつ易分散性の炭化ケイ素ナノ粒子11を得ることができる。
なお、必要により、表面酸化層3を溶解除去した後に、炭化ケイ素ナノ粒子11の表面を、水やアルコールなどの溶液を用いて洗浄しても良い。
In these methods, since the removal of the surface oxide layer is not accompanied by heating, aggregation of silicon carbide nanoparticles can be suppressed. As a result, as shown in FIG. 1C, silicon carbide nanoparticles 11 having high purity and easy dispersibility can be obtained.
If necessary, after the surface oxide layer 3 is dissolved and removed, the surface of the silicon carbide nanoparticles 11 may be washed with a solution such as water or alcohol.

このようにして得られた高純度かつ易分散性の炭化ケイ素ナノ粒子11を、図1(d)に示すように、分散媒4中に分散させて、炭化ケイ素ナノ粒子分散液とする。
この分散工程は、湿式法によることが好ましい。
この湿式法で用いられる分散機は、開放型、密閉型のいずれも使用可能であり、例えば、ボールミル、攪拌ミル等が挙げられる。ボールミルとしては、転動ボールミル、振動ボールミル、遊星ミル等が挙げられる。また、攪拌ミルとしては、塔式ミル、攪拌槽型ミル、流通管式ミル、管状ミル等が挙げられる。
The high-purity and easily dispersible silicon carbide nanoparticles 11 thus obtained are dispersed in the dispersion medium 4 as shown in FIG. 1 (d) to obtain a silicon carbide nanoparticle dispersion.
This dispersing step is preferably performed by a wet method.
The disperser used in this wet method can be either an open type or a closed type, and examples thereof include a ball mill and a stirring mill. Examples of the ball mill include a rolling ball mill, a vibration ball mill, and a planetary mill. Examples of the stirring mill include a tower mill, a stirring tank mill, a flow pipe mill, and a tubular mill.

ボールミルや攪拌ミルを用いて炭化ケイ素ナノ粒子を分散させる場合、使用するメディアは特に限定されないが、その平均粒径は1μm〜1mmが好ましく、10〜500μmがより好ましい。ここで、メディアの平均粒径を1μm〜1mmとした理由は、メディアの平均粒径が1μm未満であると、メディアと分散媒との分離が困難となるからであり、一方、メディアの平均粒径が1mmより大きいと、分散効率が低下するからである。
メディアの材質は、ガラス、ジルコニア等のセラミックス、あるいはステンレス等の金属が使用可能であるが、耐摩耗性に優れ、化学的に安定である点からジルコニアを使用することが好ましい。
When the silicon carbide nanoparticles are dispersed using a ball mill or a stirring mill, the medium to be used is not particularly limited, but the average particle diameter is preferably 1 μm to 1 mm, more preferably 10 to 500 μm. Here, the reason why the average particle size of the media is 1 μm to 1 mm is that when the average particle size of the media is less than 1 μm, it becomes difficult to separate the media and the dispersion medium, This is because the dispersion efficiency decreases when the diameter is larger than 1 mm.
As the material of the media, glass, ceramics such as zirconia, or metals such as stainless steel can be used. However, it is preferable to use zirconia because it is excellent in wear resistance and chemically stable.

この炭化ケイ素ナノ粒子を分散させる分散媒は、基本的には、水及び/又は有機溶媒であるが、その他、高分子モノマーやオリゴマーの単体もしくはこれらの混合物も好適に用いられる。
上記の有機溶媒としては、例えば、メタノール、エタノール、プロパノール、ジアセトンアルコール、フリフリルアルコール、エチレングリコール、へキシレングリコール等のアルコール類、酢酸メチルエステル、酢酸エチルエステル等のエステル類、ジエチルエーテル、エチレングリコールモノメチルエーテル(メチルセロソルブ)、エチレングリコールモノエチルエーテル(エチルセロソルブ)、エチレングリコールモノブチルエーテル(ブチルセロソルブ)、ジエチレングリコールモノメチルエーテル、エチレングリコールモノエチルエーテル等のエーテルアルコール類、ジオキサン、テトラヒドロフラン等のエーテル類、アセトン、メチルエチルケトン、アセチルアセトン、アセト酢酸エステル等のケトン類、N,N−ジメチルホルムアミド等の酸アミド類、トルエン、キシレン等の芳香族炭化水素等が好適に用いられ、これらの溶媒のうち1種または2種以上を用いることができる。
The dispersion medium in which the silicon carbide nanoparticles are dispersed is basically water and / or an organic solvent, but in addition, a single polymer monomer or oligomer or a mixture thereof is also preferably used.
Examples of the organic solvent include alcohols such as methanol, ethanol, propanol, diacetone alcohol, furfuryl alcohol, ethylene glycol and hexylene glycol, esters such as acetic acid methyl ester and ethyl acetate, diethyl ether, ethylene Glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), ether alcohols such as diethylene glycol monomethyl ether and ethylene glycol monoethyl ether, ethers such as dioxane and tetrahydrofuran, acetone , Ketones such as methyl ethyl ketone, acetylacetone, acetoacetate, N, N-dimethylform Acid amides such as amide, toluene, aromatic hydrocarbon or the like is preferably used, such as xylene, may be used alone or two or more of these solvents.

上記の高分子モノマーとしては、アクリル酸メチル、メタクリル酸メチル等のアクリル系またはメタクリル系のモノマー、エポキシ系モノマー等が好適に用いられる。
また、上記のオリゴマーとしては、ウレタンアクリレート系オリゴマー、エポキシアクリレート系オリゴマー、アクリレート系オリゴマー等が好適に用いられる。
As the polymer monomer, acrylic or methacrylic monomers such as methyl acrylate and methyl methacrylate, epoxy monomers, and the like are preferably used.
Moreover, as said oligomer, a urethane acrylate oligomer, an epoxy acrylate oligomer, an acrylate oligomer etc. are used suitably.

なお、この炭化ケイ素ナノ粒子と分散媒との親和性を高めるために、炭化ケイ素ナノ粒子の表面改質を行っても良い。表面改質剤としては、3−アミノプロピルトリメトキシシラン、3−アミノプロピルトリエトキシシラン、システアミン、テトラメチルアンモニウムヒドロキシド、アミノエタンジオール等が挙げられるが、これらに限定されるものではなく、炭化ケイ素ナノ粒子の表面に吸着する官能基を有し、かつ分散媒と親和性を持つ末端基を有する表面改質剤であれば良い。   In addition, in order to improve the affinity between the silicon carbide nanoparticles and the dispersion medium, the surface modification of the silicon carbide nanoparticles may be performed. Examples of the surface modifier include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, cysteamine, tetramethylammonium hydroxide, aminoethanediol, and the like, but are not limited thereto. Any surface modifier may be used as long as it has a functional group adsorbed on the surface of the silicon nanoparticles and has a terminal group having an affinity for the dispersion medium.

また、この分散工程に、ホモミキサー、ホモジナイザー等の他の分散機を用いた予備混合を導入しても良い。予備混合を行うことにより、凝集した炭化ケイ素ナノ粒子が解砕・粉砕され、その後の分散に要する負荷を低減し、効率良く炭化ケイ素ナノ粒子を分散させることができる。   Moreover, you may introduce | transduce into this dispersion | distribution process the preliminary mixing using other dispersers, such as a homomixer and a homogenizer. By performing premixing, the agglomerated silicon carbide nanoparticles are crushed and pulverized, the load required for subsequent dispersion can be reduced, and the silicon carbide nanoparticles can be efficiently dispersed.

「炭化ケイ素ナノ粒子分散液」
本発明の炭化ケイ素ナノ粒子分散液は、本発明の炭化ケイ素ナノ粒子分散液の製造方法により作製されたものである。
この炭化ケイ素ナノ粒子分散液に、炭化ケイ素ナノ粒子の分散性を阻害しないバインダー成分、例えば、シリカ微粒子、ケイ素有機化合物等のシリカゾル、あるいは熱硬化性樹脂等を添加してもよい。
"Silicon carbide nanoparticle dispersion"
The silicon carbide nanoparticle dispersion of the present invention is produced by the method for producing a silicon carbide nanoparticle dispersion of the present invention.
A binder component that does not inhibit the dispersibility of the silicon carbide nanoparticles, for example, silica fine particles, a silica sol such as a silicon organic compound, or a thermosetting resin may be added to the silicon carbide nanoparticle dispersion.

上記のバインダー成分は、炭化ケイ素ナノ粒子100重量部に対し、1〜30重量部であることが好ましい。ここで、バインダー成分を1〜30重量部と限定した理由は、1重量部より少ないと、被処理物と塗膜との密着性が悪く、摺動の際に炭化ケイ素ナノ粒子が脱粒し易くなり、その結果、擦傷が発生して部材が損傷するからであり、一方、30重量部より多いと、バインダー成分が多すぎて塗膜の硬質性が低下し、耐磨耗性、耐擦傷性が低下するからである。
この炭化ケイ素ナノ粒子分散液は、高純度であると共に、分散性及び分散安定性に優れたものであり、その結果、長期間に亘って分散液の諸特性を維持し続けることができる。
It is preferable that said binder component is 1-30 weight part with respect to 100 weight part of silicon carbide nanoparticles. Here, the reason why the binder component is limited to 1 to 30 parts by weight is that when the amount is less than 1 part by weight, the adhesion between the object to be processed and the coating film is poor, and the silicon carbide nanoparticles are easily shed when sliding. As a result, scratches are generated and the member is damaged. On the other hand, if it exceeds 30 parts by weight, the binder component is too much and the hardness of the coating film is lowered, resulting in wear resistance and scratch resistance. This is because of a decrease.
This silicon carbide nanoparticle dispersion has high purity and is excellent in dispersibility and dispersion stability, and as a result, the various characteristics of the dispersion can be maintained over a long period of time.

「炭化ケイ素ナノ粒子膜」
本発明の炭化ケイ素ナノ粒子膜は、被処理物上に本発明の炭化ケイ素ナノ粒子分散液を塗布して形成された塗膜を、熱処理することで得られる。
被処理物としては、熱処理温度に耐える材質であればよく、ガラス等のセラミックス、金属等が好適に用いられる。なお、熱処理温度が300℃以下のように低温の場合には、熱変形が生じないのであれば、耐熱性ポリマーやプラスチックも用いることができる。
この被処理物の形状としては、2次元の平板形状、3次元の立体形状のいずれも用いることが可能である。
"Silicon carbide nanoparticle film"
The silicon carbide nanoparticle film of the present invention can be obtained by heat-treating a coating film formed by applying the silicon carbide nanoparticle dispersion of the present invention on an object to be treated.
The material to be processed may be any material that can withstand the heat treatment temperature, and ceramics such as glass, metal, and the like are preferably used. In the case where the heat treatment temperature is as low as 300 ° C. or lower, a heat resistant polymer or plastic can be used as long as thermal deformation does not occur.
As the shape of the object to be processed, any of a two-dimensional flat plate shape and a three-dimensional solid shape can be used.

塗布方法は、被処理物の形状に合わせて適宜選択すればよく、例えば、スピンコート法、ロールコート法、スプレーコート法、バーコート法、ディップコート法、グラビア印刷法、スクリーン印刷法、インクジェット印刷法等、分散液を被処理物の表面に塗布する通常のウェットコート法を用いることができる。
塗布に際しては、耐摩耗性、耐擦傷性、耐熱性、硬度の各特性が満たされれば特に限定されないが、炭化ケイ素ナノ粒子膜の膜厚が0.1〜10μmとなるように塗布量を調整することが好ましい。
The coating method may be appropriately selected according to the shape of the object to be processed. For example, spin coating, roll coating, spray coating, bar coating, dip coating, gravure printing, screen printing, ink jet printing The usual wet coat method which apply | coats a dispersion liquid to the surface of a to-be-processed object, such as a method, can be used.
The application is not particularly limited as long as the properties of wear resistance, scratch resistance, heat resistance, and hardness are satisfied, but the coating amount is adjusted so that the film thickness of the silicon carbide nanoparticle film is 0.1 to 10 μm. It is preferable to do.

熱処理については、雰囲気は特に限定されないが、例えば、水素や一酸化炭素等の還元性雰囲気、窒素、アルゴン、ネオン、キセノン等の不活性雰囲気、酸素、大気等の酸化性雰囲気が、膜の特性等に応じて適宜選択される。
熱処理温度は、100℃以上が好ましい。その理由は、100℃未満の温度で熱処理すると、添加しているバインダーの硬化反応が生じ難くなり、目的とする表面硬度が得られなくなるからである。塗膜の密着性やバインダーの硬化性の観点からは、熱処理温度は高い方が望ましく、熱処理温度の上限は選択される被処理物の耐熱温度付近であることが好ましい。
Regarding the heat treatment, the atmosphere is not particularly limited. For example, a reducing atmosphere such as hydrogen or carbon monoxide, an inert atmosphere such as nitrogen, argon, neon, or xenon, or an oxidizing atmosphere such as oxygen or air may be used as a film characteristic. It is appropriately selected depending on the like.
The heat treatment temperature is preferably 100 ° C. or higher. The reason is that if the heat treatment is performed at a temperature of less than 100 ° C., the curing reaction of the added binder hardly occurs, and the desired surface hardness cannot be obtained. From the viewpoint of the adhesion of the coating film and the curability of the binder, it is desirable that the heat treatment temperature is high, and the upper limit of the heat treatment temperature is preferably near the heat resistance temperature of the object to be selected.

本発明の炭化ケイ素ナノ粒子膜は、被処理物への密着性が良好であり、耐磨耗性、耐擦傷性、耐熱性、硬質性に優れる。したがって、軸受や摺動部材等の耐磨耗性被膜、耐擦傷性被膜、耐熱性被膜、硬質性被膜等として好適に用いることができる。   The silicon carbide nanoparticle film of the present invention has good adhesion to an object to be treated, and is excellent in wear resistance, scratch resistance, heat resistance and hardness. Therefore, it can be suitably used as a wear-resistant coating, a scratch-resistant coating, a heat-resistant coating, a hard coating, etc. for bearings and sliding members.

以下、実施例及び比較例により本発明を具体的に説明するが、本発明はこれらの実施例によって限定されるものではない。   EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited by these Examples.

「実施例1」
(炭化珪素ナノ粒子分散液の調製)
平均粒径30nm、炭素質2重量%の炭化ケイ素ナノ粒子(住友大阪セメント製:熱プラズマ法)を大気中、600℃にて5時間熱処理を行い、炭化ケイ素ナノ粒子の表面に酸化層を形成した。
次いで、この表面酸化層付き炭化ケイ素ナノ粒子を、混酸(フッ酸:硝酸=5:1(重量比))に浸漬し、1時間室温にて攪拌して、表面酸化層の溶解除去を行った。
次いで、混酸をホットプレート上で蒸発させ、乾燥した炭化ケイ素ナノ粒子を回収し、その後、0.1N−アンモニア水にて洗浄を行った。洗浄後、真空乾燥し、易分散性の炭化ケイ素ナノ粒子を得た。
"Example 1"
(Preparation of silicon carbide nanoparticle dispersion)
Silicon carbide nanoparticles with an average particle size of 30 nm and 2% by weight of carbon (Sumitomo Osaka Cement: Thermal Plasma Method) are heat-treated in the atmosphere at 600 ° C. for 5 hours to form an oxide layer on the surface of the silicon carbide nanoparticles did.
Next, the surface-oxidized layer-coated silicon carbide nanoparticles were immersed in a mixed acid (hydrofluoric acid: nitric acid = 5: 1 (weight ratio)) and stirred at room temperature for 1 hour to dissolve and remove the surface oxidized layer. .
Next, the mixed acid was evaporated on a hot plate, and the dried silicon carbide nanoparticles were collected, and then washed with 0.1N ammonia water. After washing, vacuum drying was performed to obtain easily dispersible silicon carbide nanoparticles.

次いで、この易分散性の炭化ケイ素ナノ粒子10重量部、アンモニア水0.1重量部、純水49.9重量部及びエタノール40重量部を混合し、全体量が100gの原料液を得た。
次いで、この原料液にジルコニアビーズ(直径0.1mm)400重量部を加え、開放型サンドミル分散機にて回転数2500rpmの条件にて7時間、分散処理を行った。その後、ジルコニアビーズを分離した。その結果、得られた分散液中の炭化ケイ素ナノ粒子の濃度は10重量%であった。
Subsequently, 10 parts by weight of the easily dispersible silicon carbide nanoparticles, 0.1 part by weight of ammonia water, 49.9 parts by weight of pure water and 40 parts by weight of ethanol were mixed to obtain a raw material liquid having a total amount of 100 g.
Next, 400 parts by weight of zirconia beads (diameter: 0.1 mm) was added to this raw material liquid, and the dispersion treatment was performed for 7 hours under the condition of 2500 rpm with an open sand mill disperser. Thereafter, the zirconia beads were separated. As a result, the concentration of silicon carbide nanoparticles in the obtained dispersion was 10% by weight.

次いで、得られた分散液を純水で希釈し、炭化ケイ素濃度を0.1重量%とした懸濁液を調整した。その後、この懸濁液について、動的光散乱粒径分布測定装置(Malvern社製)を用いて動的光散乱法による粒度分布測定を行った。測定結果を表1に示す。
この測定結果によれば、分散粒径が100nm未満と微細であることから、分散性に優れていることがわかった。また、この分散液を室温(25℃)にて1ヶ月間放置した後、同様の方法で粒度分布を測定したが、分散粒径に変化はなく、また炭化ケイ素ナノ粒子の顕著な沈降等も認められず、分散安定性も良好であった。
Next, the obtained dispersion was diluted with pure water to prepare a suspension having a silicon carbide concentration of 0.1% by weight. Thereafter, the suspension was subjected to particle size distribution measurement by a dynamic light scattering method using a dynamic light scattering particle size distribution measuring apparatus (manufactured by Malvern). The measurement results are shown in Table 1.
According to this measurement result, it was found that the dispersibility is excellent because the dispersed particle diameter is as fine as less than 100 nm. The dispersion was allowed to stand at room temperature (25 ° C.) for 1 month, and the particle size distribution was measured by the same method. However, there was no change in the dispersed particle size, and significant precipitation of silicon carbide nanoparticles occurred. The dispersion stability was also good.

(炭化ケイ素ナノ粒子塗料の調製)
上記の分散液30重量部、メタノール25重量部、エチレングリコール40重量部及びシリカゾル5重量部を混合して、炭化ケイ素ナノ粒子塗料とした。
なお、シリカゾルは、テトラエトキシシラン33重量部をエタノール46重量部で希釈し、この希釈液に1N−アンモニア水を3重量部、純水を18重量部加えて混合し、その後、60℃にて2時間加熱することで得た。
(Preparation of silicon carbide nanoparticle paint)
30 parts by weight of the above dispersion, 25 parts by weight of methanol, 40 parts by weight of ethylene glycol and 5 parts by weight of silica sol were mixed to obtain a silicon carbide nanoparticle coating material.
The silica sol was prepared by diluting 33 parts by weight of tetraethoxysilane with 46 parts by weight of ethanol, adding 3 parts by weight of 1N ammonia water and 18 parts by weight of pure water to the diluted solution, and then mixing at 60 ° C. Obtained by heating for 2 hours.

(炭化ケイ素ナノ粒子膜の作製)
上記の炭化ケイ素ナノ粒子塗料をスピンコート法により、厚み2mmのステンレス基板(SUS304)に塗布し、その後、大気中、200℃にて熱処理し、膜厚が約400nmの炭化ケイ素ナノ粒子膜を作製した。
この炭化ケイ素ナノ粒子膜の表面粗さ(Ra)、表面硬度(GPa)、鉛筆硬度を測定した。また、炭化ケイ素ナノ粒子膜の耐久性を調べるため、磨耗試験及び耐熱試験を行った。
(Production of silicon carbide nanoparticle film)
The silicon carbide nanoparticle coating is applied to a 2 mm thick stainless steel substrate (SUS304) by spin coating, and then heat treated at 200 ° C. in the atmosphere to produce a silicon carbide nanoparticle film having a thickness of about 400 nm. did.
The surface roughness (Ra), surface hardness (GPa), and pencil hardness of this silicon carbide nanoparticle film were measured. Moreover, in order to investigate the durability of the silicon carbide nanoparticle film, an abrasion test and a heat resistance test were performed.

測定方法及び試験方法は以下の通りである。
(1)表面粗さ(Ra):日本工業規格JIS B 0601に準じ、表面粗さ測定機(ミツトヨ社製)にて測定した。
(2)表面硬度(GPa):ナノインデンター(MTS社製)にて、表面深さ200nmの硬度を測定した。
(3)鉛筆硬度:日本工業規格JIS K 5400に準じ測定した。
The measurement method and test method are as follows.
(1) Surface roughness (Ra): Measured with a surface roughness measuring machine (Mitutoyo Co., Ltd.) according to Japanese Industrial Standard JIS B 0601.
(2) Surface hardness (GPa): The hardness at a surface depth of 200 nm was measured with a nanoindenter (manufactured by MTS).
(3) Pencil hardness: Measured according to Japanese Industrial Standard JIS K 5400.

(4)磨耗試験:直径18mmのガラス棒先端に炭化ケイ素ナノ粒子膜を形成し、試験片とした。試験片にかかる荷重:10N、静止相手材:ステンレス鋼(SUS304)、ストローク:50mm、50往復/分の条件にて往復運動平面磨耗試験を3万回行い、炭化ケイ素ナノ粒子膜の状態を観察した。ここでは、金属面が露出しなかったものを「○」、金属面が露出したものを「×」とした。
(5)耐熱試験:炭化ケイ素ナノ粒子膜を形成したステンレス基板(SUS304)について、大気中、室温(25℃)から500℃までの昇降温を10回繰り返し、炭化ケイ素ナノ粒子膜の状態を観察した。ここでは、膜剥れやクラックの発生しなかったものを「○」、クラックの発生したものを「△」、膜剥れしたものを「×」とした。
これらの測定結果を表1に示す。
(4) Abrasion test: A silicon carbide nanoparticle film was formed on the tip of a glass rod having a diameter of 18 mm to obtain a test piece. The load applied to the test piece: 10 N, stationary counterpart: stainless steel (SUS304), stroke: 50 mm, reciprocating plane wear test at 30,000 reciprocations / minute, 30,000 times, and observing the state of the silicon carbide nanoparticle film did. Here, the case where the metal surface was not exposed was indicated by “◯”, and the case where the metal surface was exposed was indicated by “X”.
(5) Heat resistance test: For a stainless steel substrate (SUS304) on which a silicon carbide nanoparticle film is formed, the temperature rise from room temperature (25 ° C) to 500 ° C is repeated 10 times in the air, and the state of the silicon carbide nanoparticle film is observed. did. Here, “◯” indicates that no film peeling or crack occurred, “Δ” indicates that a crack occurred, and “X” indicates that the film peeled.
These measurement results are shown in Table 1.

この炭化ケイ素ナノ粒子膜は、表面粗さが小さく、硬度が高いため、膜面に擦傷の発生も無く、耐磨耗性、耐擦傷性、硬質性に優れていた。また、耐熱試験においても炭化ケイ素ナノ粒子膜の剥れやクラックの発生、膜の変質等は認められず、耐熱性が良好であることが示された。   Since this silicon carbide nanoparticle film had a small surface roughness and high hardness, there was no generation of scratches on the film surface, and it was excellent in wear resistance, scratch resistance, and hardness. Further, in the heat resistance test, no peeling or cracking of the silicon carbide nanoparticle film, alteration of the film, etc. were observed, indicating that the heat resistance was good.

「実施例2」
実施例1で、平均粒径30nm、炭素質2重量%の炭化ケイ素ナノ粒子(住友大阪セメント製:熱プラズマ法)を、平均粒径15nm、炭素質4重量%の炭化ケイ素ナノ粒子(住友大阪セメント製:シリカ前駆体焼成法)に替えた他は、実施例1に準じて実施例2の炭化ケイ素ナノ粒子分散液、炭化ケイ素ナノ粒子塗料及び炭化ケイ素ナノ粒子膜を作製した。
"Example 2"
In Example 1, silicon carbide nanoparticles (Sumitomo Osaka Cement: Thermal Plasma Method) with an average particle size of 30 nm and carbonaceous material of 2% by weight were used as silicon carbide nanoparticles (Sumitomo Osaka Osaka) with an average particle size of 15 nm and carbonaceous material of 4% by weight. A silicon carbide nanoparticle dispersion, a silicon carbide nanoparticle coating material, and a silicon carbide nanoparticle film of Example 2 were produced according to Example 1 except that the method was changed to “Cement made: Silica precursor firing method”.

次いで、実施例1に準じて、炭化ケイ素ナノ粒子分散液の粒度分布測定を行った。測定結果を表1に示す。
この測定結果によれば、分散粒径が100nm未満と微細であることから、分散性に優れていることがわかった。また、この分散液を室温(25℃)にて1ヶ月間放置した後、同様の方法で粒度分布を測定したが、分散粒径に変化はなく、また炭化ケイ素ナノ粒子の顕著な沈降等も認められず、分散安定性も良好であった。
Subsequently, according to Example 1, the particle size distribution measurement of the silicon carbide nanoparticle dispersion was performed. The measurement results are shown in Table 1.
According to this measurement result, it was found that the dispersibility is excellent because the dispersed particle diameter is as fine as less than 100 nm. The dispersion was allowed to stand at room temperature (25 ° C.) for 1 month, and the particle size distribution was measured by the same method. However, there was no change in the dispersed particle size, and significant precipitation of silicon carbide nanoparticles occurred. The dispersion stability was also good.

次いで、実施例1に準じて、炭化ケイ素ナノ粒子膜の表面粗さ(Ra)、表面硬度(GPa)、鉛筆硬度を測定した。また、炭化ケイ素ナノ粒子膜の耐久性を調べるため、磨耗試験及び耐熱試験を行った。これらの測定結果を表1に示す。
この炭化ケイ素ナノ粒子膜は、表面粗さが小さく、硬度が高いため、膜面に擦傷の発生も無く、耐磨耗性、耐擦傷性、硬質性に優れていた。また、耐熱試験においても炭化ケイ素ナノ粒子膜の剥れやクラックの発生、膜の変質等は認められず、耐熱性が良好であることが示された。
Subsequently, according to Example 1, the surface roughness (Ra), surface hardness (GPa), and pencil hardness of the silicon carbide nanoparticle film were measured. Moreover, in order to investigate the durability of the silicon carbide nanoparticle film, an abrasion test and a heat resistance test were performed. These measurement results are shown in Table 1.
Since this silicon carbide nanoparticle film had a small surface roughness and high hardness, there was no generation of scratches on the film surface, and it was excellent in wear resistance, scratch resistance, and hardness. Further, in the heat resistance test, no peeling or cracking of the silicon carbide nanoparticle film, alteration of the film, etc. were observed, indicating that the heat resistance was good.

「実施例3」
実施例2で原料液を、易分散性の炭化ケイ素ナノ粒子10重量部、アンモニア水1重量部、純水39重量部及びメタノール50重量部を混合し、全体量を100gとした原料液に替えた他は、実施例2に準じて実施例3の炭化ケイ素ナノ粒子分散液、炭化ケイ素ナノ粒子塗料及び炭化ケイ素ナノ粒子膜を作製した。
"Example 3"
In Example 2, the raw material liquid was changed to a raw material liquid in which 10 parts by weight of easily dispersible silicon carbide nanoparticles, 1 part by weight of ammonia water, 39 parts by weight of pure water and 50 parts by weight of methanol were mixed to make the total amount 100 g. Other than that, the silicon carbide nanoparticle dispersion liquid, silicon carbide nanoparticle coating material, and silicon carbide nanoparticle film of Example 3 were produced according to Example 2.

次いで、実施例1に準じて、炭化ケイ素ナノ粒子分散液の粒度分布測定を行った。測定結果を表1に示す。
この測定結果によれば、分散粒径が100nm未満と微細であることから、分散性に優れていることがわかった。また、この分散液を室温(25℃)にて1ヶ月間放置した後、同様の方法で粒度分布を測定したが、分散粒径に変化はなく、また炭化ケイ素ナノ粒子の顕著な沈降等も認められず、分散安定性も良好であった。
Subsequently, according to Example 1, the particle size distribution measurement of the silicon carbide nanoparticle dispersion was performed. The measurement results are shown in Table 1.
According to this measurement result, it was found that the dispersibility is excellent because the dispersed particle diameter is as fine as less than 100 nm. The dispersion was allowed to stand at room temperature (25 ° C.) for 1 month, and the particle size distribution was measured by the same method. However, there was no change in the dispersed particle size, and significant precipitation of silicon carbide nanoparticles occurred. The dispersion stability was also good.

次いで、実施例1に準じて、炭化ケイ素ナノ粒子膜の表面粗さ(Ra)、表面硬度(GPa)、鉛筆硬度を測定した。また、炭化ケイ素ナノ粒子膜の耐久性を調べるため、磨耗試験及び耐熱試験を行った。これらの測定結果を表1に示す。
この炭化ケイ素ナノ粒子膜は、表面粗さが小さく、硬度が高いため、膜面に擦傷の発生も無く、耐磨耗性、耐擦傷性、硬質性に優れていた。また、耐熱試験においても炭化ケイ素ナノ粒子膜の剥れやクラックの発生、膜の変質等は認められず、耐熱性が良好であることが示された。
Subsequently, according to Example 1, the surface roughness (Ra), surface hardness (GPa), and pencil hardness of the silicon carbide nanoparticle film were measured. Moreover, in order to investigate the durability of the silicon carbide nanoparticle film, an abrasion test and a heat resistance test were performed. These measurement results are shown in Table 1.
Since this silicon carbide nanoparticle film had a small surface roughness and high hardness, there was no generation of scratches on the film surface, and it was excellent in wear resistance, scratch resistance, and hardness. Further, in the heat resistance test, no peeling or cracking of the silicon carbide nanoparticle film, alteration of the film, etc. were observed, indicating that the heat resistance was good.

「比較例1」
実施例1で用いた平均粒径30nm、炭素質2重量%の炭化ケイ素ナノ粒子(住友大阪セメント製:熱プラズマ法)を、そのまま原料粉末とした。
次いで、この炭化ケイ素ナノ粒子10重量部、セルナD−735(中京油脂社製)1.5重量部、アンモニア水0.1重量部、純水48.4重量部及びエタノール40重量部を混合し、全体量が100gの原料液を得た。
次いで、この原料液を用い、実施例1に準じて比較例1の炭化ケイ素ナノ粒子分散液、炭化ケイ素ナノ粒子塗料及び炭化ケイ素ナノ粒子膜を作製した。
"Comparative Example 1"
The silicon carbide nanoparticles (manufactured by Sumitomo Osaka Cement: Thermal Plasma Method) having an average particle size of 30 nm and 2% by weight of carbon used in Example 1 were directly used as raw material powders.
Next, 10 parts by weight of the silicon carbide nanoparticles, 1.5 parts by weight of Serna D-735 (manufactured by Chukyo Yushi Co., Ltd.), 0.1 part by weight of ammonia water, 48.4 parts by weight of pure water and 40 parts by weight of ethanol were mixed. A raw material liquid having a total amount of 100 g was obtained.
Next, using this raw material liquid, a silicon carbide nanoparticle dispersion liquid, a silicon carbide nanoparticle coating material, and a silicon carbide nanoparticle film of Comparative Example 1 were produced according to Example 1.

次いで、実施例1に準じて、炭化ケイ素ナノ粒子分散液の粒度分布測定を行った。測定結果を表1に示す。
この測定結果によれば、分散粒径が100nm以上と大きく、分散性が悪化していた。また、この分散液を室温(25℃)にて1ヶ月間放置したところ、炭化ケイ素ナノ粒子が沈降し、分散安定性も劣っていた。
Subsequently, according to Example 1, the particle size distribution measurement of the silicon carbide nanoparticle dispersion was performed. The measurement results are shown in Table 1.
According to this measurement result, the dispersed particle size was as large as 100 nm or more, and the dispersibility was deteriorated. Further, when this dispersion was allowed to stand at room temperature (25 ° C.) for 1 month, silicon carbide nanoparticles settled and the dispersion stability was poor.

次いで、実施例1に準じて、炭化ケイ素ナノ粒子膜の表面粗さ(Ra)、表面硬度(GPa)、鉛筆硬度を測定した。また、炭化ケイ素ナノ粒子膜の耐久性を調べるため、磨耗試験及び耐熱試験を行った。これらの測定結果を表1に示す。
この炭化ケイ素ナノ粒子膜は、表面粗さが大きく、塗膜に炭素質が含まれるために硬度が低く、膜面に擦傷が多数発生し、耐摩耗性、耐擦傷性、硬質性に劣ったものであった。また、耐熱試験においても炭化ケイ素ナノ粒子膜に剥れが発生し、熱による劣化が顕著であった。
Subsequently, according to Example 1, the surface roughness (Ra), surface hardness (GPa), and pencil hardness of the silicon carbide nanoparticle film were measured. Moreover, in order to investigate the durability of the silicon carbide nanoparticle film, an abrasion test and a heat resistance test were performed. These measurement results are shown in Table 1.
This silicon carbide nanoparticle film has a large surface roughness, low hardness because the coating film contains carbonaceous matter, many scratches on the film surface, and poor wear resistance, scratch resistance, and hardness. It was a thing. Further, in the heat resistance test, the silicon carbide nanoparticle film peeled off and the deterioration due to heat was remarkable.

「比較例2」
実施例1で表面酸化層の除去処理を行わなかった他は、実施例1に準じて比較例2の炭化ケイ素ナノ粒子分散液、炭化ケイ素ナノ粒子塗料及び炭化ケイ素ナノ粒子膜を作製した。
"Comparative Example 2"
A silicon carbide nanoparticle dispersion, a silicon carbide nanoparticle coating material, and a silicon carbide nanoparticle film of Comparative Example 2 were produced in the same manner as in Example 1 except that the surface oxide layer was not removed in Example 1.

次いで、実施例1に準じて、炭化ケイ素ナノ粒子分散液の粒度分布測定を行った。測定結果を表1に示す。
この測定結果によれば、分散粒径が100nm以上と大きく、分散性が悪化していた。また、この分散液を室温(25℃)にて1ヶ月間放置したところ、一部の炭化ケイ素ナノ粒子が沈降し、分散安定性も劣っていた。
Subsequently, according to Example 1, the particle size distribution measurement of the silicon carbide nanoparticle dispersion was performed. The measurement results are shown in Table 1.
According to this measurement result, the dispersed particle size was as large as 100 nm or more, and the dispersibility was deteriorated. When this dispersion was allowed to stand at room temperature (25 ° C.) for 1 month, some silicon carbide nanoparticles settled and the dispersion stability was poor.

次いで、実施例1に準じて、炭化ケイ素ナノ粒子膜の表面粗さ(Ra)、表面硬度(GPa)、鉛筆硬度を測定した。また、炭化ケイ素ナノ粒子膜の耐久性を調べるため、磨耗試験及び耐熱試験を行った。これらの測定結果を表1に示す。
この炭化ケイ素ナノ粒子膜は、塗膜に表面酸化層によるシリカ分が多く含まれるために、硬度が低く、膜面に擦傷が発生し、耐摩耗性、耐擦傷性、硬質性に劣っていた。また、耐熱試験においても、炭化ケイ素ナノ粒子膜にクラックが発生し、熱による劣化が顕著であった。
Subsequently, according to Example 1, the surface roughness (Ra), surface hardness (GPa), and pencil hardness of the silicon carbide nanoparticle film were measured. Moreover, in order to investigate the durability of the silicon carbide nanoparticle film, an abrasion test and a heat resistance test were performed. These measurement results are shown in Table 1.
Since this silicon carbide nanoparticle film contains a large amount of silica due to the surface oxide layer in the coating film, it has low hardness, scratches on the film surface, and is inferior in wear resistance, scratch resistance, and hardness. . In the heat resistance test, cracks were generated in the silicon carbide nanoparticle film, and deterioration due to heat was significant.

Figure 2009013025
Figure 2009013025

本発明の炭化ケイ素ナノ粒子分散液の製造方法は、炭化ケイ素ナノ粒子同士の凝集を抑制することで分散性及び分散安定性が向上した炭化ケイ素ナノ粒子分散液を可能としたものであるから、耐磨耗性被膜、耐擦傷性被膜、耐熱性被膜、硬質性被膜等を形成するための塗料や複合メッキ用のフィラーへの応用はもちろんのこと、これ以外のさまざまな工業分野においてもその利用可能性は大である。   Since the method for producing a silicon carbide nanoparticle dispersion of the present invention enables a silicon carbide nanoparticle dispersion having improved dispersibility and dispersion stability by suppressing aggregation of silicon carbide nanoparticles, Use in paints and fillers for composite plating to form wear-resistant coatings, scratch-resistant coatings, heat-resistant coatings, hard coatings, and other various industrial fields The potential is great.

本発明の一実施形態の炭化ケイ素ナノ粒子分散液の製造方法を示す過程図である。It is process drawing which shows the manufacturing method of the silicon carbide nanoparticle dispersion liquid of one Embodiment of this invention.

符号の説明Explanation of symbols

1 凝集性を有する炭化ケイ素ナノ粒子
2 フリーカーボン等の炭素質
3 表面酸化層
4 分散媒
11 易分散性の炭化ケイ素ナノ粒子
DESCRIPTION OF SYMBOLS 1 Silicon carbide nanoparticle which has cohesiveness 2 Carbonaceous materials, such as free carbon 3 Surface oxide layer 4 Dispersion medium 11 Easily dispersible silicon carbide nanoparticle

Claims (8)

炭化ケイ素ナノ粒子の表面に酸化処理を施して表面酸化層を形成し、次いで、この炭化ケイ素ナノ粒子の表面酸化層を除去し、次いで、この表面酸化層が除去された炭化ケイ素ナノ粒子を分散媒中に分散させることを特徴とする炭化ケイ素ナノ粒子分散液の製造方法。   The surface of the silicon carbide nanoparticles is oxidized to form a surface oxide layer, then the surface oxide layer of the silicon carbide nanoparticles is removed, and then the silicon carbide nanoparticles from which the surface oxide layer has been removed are dispersed. A method for producing a silicon carbide nanoparticle dispersion, wherein the dispersion is dispersed in a medium. 前記炭化ケイ素ナノ粒子の一次粒子の平均粒子径は、5nm以上かつ500nm以下であることを特徴とする請求項1記載の炭化ケイ素ナノ粒子分散液の製造方法。   2. The method for producing a silicon carbide nanoparticle dispersion according to claim 1, wherein an average particle diameter of primary particles of the silicon carbide nanoparticles is 5 nm or more and 500 nm or less. 前記酸化処理は、酸化性雰囲気下、300℃以上かつ800℃以下の温度範囲での熱処理であることを特徴とする請求項1または2記載の炭化ケイ素ナノ粒子分散液の製造方法。   The method for producing a silicon carbide nanoparticle dispersion according to claim 1 or 2, wherein the oxidation treatment is a heat treatment in an oxidizing atmosphere in a temperature range of 300 ° C or higher and 800 ° C or lower. 前記炭化ケイ素ナノ粒子の表面酸化層を、還元性雰囲気下または不活性雰囲気下にて熱処理し、前記表面酸化層を除去することを特徴とする請求項1、2または3記載の炭化ケイ素ナノ粒子分散液の製造方法。   4. The silicon carbide nanoparticles according to claim 1, wherein the surface oxide layer of the silicon carbide nanoparticles is heat-treated in a reducing atmosphere or an inert atmosphere to remove the surface oxide layer. 5. A method for producing a dispersion. 前記炭化ケイ素ナノ粒子の表面酸化層を、フッ酸、フッ化アンモニウム、硝酸の群から選択された1種または2種以上を含む溶液を用いて溶解し、前記表面酸化層を除去することを特徴とする請求項1、2または3記載の炭化ケイ素ナノ粒子分散液の製造方法。   The surface oxide layer of the silicon carbide nanoparticles is dissolved using a solution containing one or more selected from the group consisting of hydrofluoric acid, ammonium fluoride, and nitric acid, and the surface oxide layer is removed. A method for producing a silicon carbide nanoparticle dispersion according to claim 1, 2 or 3. 前記表面酸化層が除去された炭化ケイ素ナノ粒子を、湿式法により前記分散媒中に分散させることを特徴とする請求項1ないし5のいずれか1項記載の炭化ケイ素ナノ粒子分散液の製造方法。   The method for producing a silicon carbide nanoparticle dispersion liquid according to any one of claims 1 to 5, wherein the silicon carbide nanoparticles from which the surface oxide layer has been removed are dispersed in the dispersion medium by a wet method. . 請求項1ないし6のいずれか1項記載の炭化ケイ素ナノ粒子分散液の製造方法により得られたことを特徴とする炭化ケイ素ナノ粒子分散液。   A silicon carbide nanoparticle dispersion liquid obtained by the method for producing a silicon carbide nanoparticle dispersion liquid according to any one of claims 1 to 6. 請求項7記載の炭化ケイ素ナノ粒子分散液を用いて形成された塗膜を、熱処理してなることを特徴とする炭化ケイ素ナノ粒子膜。   A silicon carbide nanoparticle film obtained by heat-treating a coating film formed using the silicon carbide nanoparticle dispersion liquid according to claim 7.
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