JP7405524B2 - Graphite material and its manufacturing method - Google Patents
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- JP7405524B2 JP7405524B2 JP2019123183A JP2019123183A JP7405524B2 JP 7405524 B2 JP7405524 B2 JP 7405524B2 JP 2019123183 A JP2019123183 A JP 2019123183A JP 2019123183 A JP2019123183 A JP 2019123183A JP 7405524 B2 JP7405524 B2 JP 7405524B2
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- 239000007770 graphite material Substances 0.000 title claims description 41
- 238000004519 manufacturing process Methods 0.000 title claims description 16
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 149
- 229910002804 graphite Inorganic materials 0.000 claims description 144
- 239000010439 graphite Substances 0.000 claims description 144
- 239000000463 material Substances 0.000 claims description 105
- 239000002245 particle Substances 0.000 claims description 85
- 239000007833 carbon precursor Substances 0.000 claims description 74
- 229910021397 glassy carbon Inorganic materials 0.000 claims description 72
- 239000011148 porous material Substances 0.000 claims description 72
- 239000010410 layer Substances 0.000 claims description 70
- 229910021470 non-graphitizable carbon Inorganic materials 0.000 claims description 68
- 239000007864 aqueous solution Substances 0.000 claims description 62
- 238000007789 sealing Methods 0.000 claims description 62
- 239000011347 resin Substances 0.000 claims description 21
- 229920005989 resin Polymers 0.000 claims description 21
- 238000005470 impregnation Methods 0.000 claims description 18
- 229920001187 thermosetting polymer Polymers 0.000 claims description 16
- 238000003763 carbonization Methods 0.000 claims description 14
- 239000002344 surface layer Substances 0.000 claims description 14
- 238000001035 drying Methods 0.000 claims description 8
- 238000010304 firing Methods 0.000 claims description 8
- 238000000034 method Methods 0.000 description 21
- 239000003575 carbonaceous material Substances 0.000 description 11
- 230000000694 effects Effects 0.000 description 6
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 6
- 229910052753 mercury Inorganic materials 0.000 description 6
- 238000001000 micrograph Methods 0.000 description 6
- 239000000758 substrate Substances 0.000 description 6
- 239000005011 phenolic resin Substances 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 239000003960 organic solvent Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 238000001723 curing Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 238000005299 abrasion Methods 0.000 description 2
- 238000010000 carbonizing Methods 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 239000000178 monomer Substances 0.000 description 2
- 239000012299 nitrogen atmosphere Substances 0.000 description 2
- 239000012454 non-polar solvent Substances 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000002243 precursor Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 239000007849 furan resin Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229910021469 graphitizable carbon Inorganic materials 0.000 description 1
- 238000005087 graphitization Methods 0.000 description 1
- 238000013007 heat curing Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 229920001568 phenolic resin Polymers 0.000 description 1
- 239000002798 polar solvent Substances 0.000 description 1
- 238000002459 porosimetry Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
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Description
本発明は黒鉛材料及びその製造方法に関し、特にガラス状カーボンの粒子が充填された黒鉛材料とその製造方法に関する。 The present invention relates to a graphite material and a method for producing the same, and more particularly to a graphite material filled with glassy carbon particles and a method for producing the same.
各種の炭素材を基体として、その表面層にガラス状炭素層を有するガラス状炭素被覆炭素材は、炭素材のガス不浸透性、耐摩耗性、化学安定性、表面硬度などを向上させたり、粉塵の発生を防止したりする部材として、各種の用途に広範に使用されている。例えば、ガラス状炭素層に要求される特性の一つである耐摩耗性に関し、炭素材であると機械的摩耗によりその表面から微粉が簡単に発生して被処理製品を汚染することに鑑みて、その表面にガラス状炭素層を形成することによって、耐摩耗性を向上させ当該微粉の発生を防ぐ。 Glassy carbon-coated carbon materials, which are based on various carbon materials and have a glassy carbon layer on the surface layer, can improve the gas impermeability, abrasion resistance, chemical stability, surface hardness, etc. of the carbon material, It is widely used in a variety of applications, including as a member to prevent the generation of dust. For example, with regard to wear resistance, which is one of the characteristics required of a glassy carbon layer, considering that carbon materials easily generate fine powder from the surface due to mechanical abrasion and contaminate the product being treated. By forming a glassy carbon layer on its surface, wear resistance is improved and generation of the fine powder is prevented .
高耐摩耗性、高固着性を備えた所謂、健全性に富んだガラス状炭素被覆炭素材として、特許文献１には炭素材から成る基体の表面層にガラス状炭素層を有するガラス状炭素被覆炭素材であって、前記ガラス状炭素層の表面が、１～５０ｃｐの粘度に調整したポリカルボジイミド樹脂を有機溶媒に溶解した溶液を用いて形成され、Ｘ線光電子分光法により測定したＯ１Ｓ及びＣ１Ｓピークの面積比Ｏ１Ｓ／Ｃ１Ｓを０．１～０．２とする表面性状を備えるガラス状炭素被覆炭素材が記載されている。 As a so-called healthy glassy carbon-coated carbon material with high wear resistance and high adhesion, Patent Document 1 describes a glassy carbon-coated carbon material having a glassy carbon layer on the surface layer of a base made of carbon material. A carbon material, the surface of the glassy carbon layer is formed using a solution in which a polycarbodiimide resin adjusted to a viscosity of 1 to 50 cp is dissolved in an organic solvent, and the O 1S and A glassy carbon-coated carbon material is described that has a surface texture in which the area ratio O 1S /C 1S of the C 1S peak is 0.1 to 0.2.
このように、上記特許文献１に記載された発明は、ポリカルボジイミド樹脂を有機溶媒に溶解した溶液、すなわち、有機溶媒で希釈したポリカルボジイミド樹脂を基体である炭素材の表面に含浸又は／及び塗布するために、ポリカルボジイミド樹脂は乾燥段階で収縮し、炭素化する際にもさらに体積が収縮する。この２段階の収縮はコントロールしにくく、炭素材の気孔を効率よく塞ぐことが難しい。 As described above, the invention described in Patent Document 1 is a solution in which a polycarbodiimide resin is dissolved in an organic solvent, that is, a polycarbodiimide resin diluted with an organic solvent is impregnated and/or applied to the surface of a carbon material as a base material. In order to do this, the polycarbodiimide resin shrinks during the drying stage and further shrinks in volume during carbonization. These two stages of shrinkage are difficult to control, and it is difficult to efficiently close the pores of the carbon material.
そこで本発明は、前記課題を鑑み、基体となる黒鉛基材の気孔が効率良くガラス状カーボンで塞がれた黒鉛材料及びその製造方法を提供することを目的とする。 In view of the above problems, the present invention aims to provide a graphite material in which the pores of a graphite base material are efficiently filled with glassy carbon, and a method for manufacturing the same.
前記課題を解決するための本発明に係る黒鉛材料は、以下のとおりである。
（１）基体となる黒鉛基材が気孔を含み、コア領域と表層に位置する封止層とから構成され、前記封止層は、前記黒鉛基材の気孔の内部にガラス状カーボンの粒子が充填された層である黒鉛材料。
The graphite material according to the present invention for solving the above problems is as follows.
(1) A graphite base material serving as a base material includes pores and is composed of a core region and a sealing layer located on the surface layer, and the sealing layer has glassy carbon particles inside the pores of the graphite base material. Graphite material that is a filled layer.
上記黒鉛材料は、黒鉛基材の表層における気孔の内部にガラス状カーボンが粒子となって充填された封止層を有することで、大きな気孔を小さくする効果が強く効率良く気孔を封止することができる。 The above-mentioned graphite material has a sealing layer filled with glassy carbon particles inside the pores in the surface layer of the graphite base material, which has a strong effect of reducing large pores and effectively seals the pores. I can do it.
本発明に係る黒鉛材料は、以下の態様であることが好ましい。 The graphite material according to the present invention preferably has the following embodiments.
（２）前記封止層の厚さが１～３０ｍｍである。 (2) The thickness of the sealing layer is 1 to 30 mm.
封止層の厚さが１ｍｍ以上であると、消耗や摩耗が生じる用途に黒鉛基材を用いた場合であっても、表面の気孔率が急激に変化しにくく、より安定した性能を維持することができる。封止層の厚さが３０ｍｍ以下であると、発生する内部応力をより小さくすることができ、高温に長時間曝された場合であっても、クリープ変形を生じにくくすることができる。 If the thickness of the sealing layer is 1 mm or more, the surface porosity will be less likely to change suddenly, and more stable performance will be maintained even when the graphite base material is used in applications where wear and tear occur. be able to. When the thickness of the sealing layer is 30 mm or less, the generated internal stress can be further reduced, and creep deformation can be made less likely to occur even when exposed to high temperatures for a long time.
（３）前記封止層の気孔率が前記コア領域の気孔率よりも低く、それらの差が１．０～５．０％である。 (3) The porosity of the sealing layer is lower than the porosity of the core region, and the difference therebetween is 1.0 to 5.0%.
封止層の気孔率と、コア領域の気孔率との差が１．０％以上であると、封止層において、黒鉛基材の気孔内部に充填されたガラス状カーボンの粒子によって、流体の浸透を十分に遮ることができ、特に反応性のガスや溶融金属との反応をより防止することができる。封止層の気孔率とコア領域の気孔率の差が５．０％以下であると、ガラス状カーボンの粒子と黒鉛基材を構成する黒鉛粒子との間に十分な距離を確保することができ、ガラス状カーボンと黒鉛との物性差に起因する歪みの発生を効果的に防止することができる。 When the difference between the porosity of the sealing layer and the porosity of the core region is 1.0% or more, the glassy carbon particles filled in the pores of the graphite base material in the sealing layer cause the fluid to flow. Penetration can be sufficiently blocked, and in particular, reactions with reactive gases and molten metals can be further prevented. When the difference between the porosity of the sealing layer and the porosity of the core region is 5.0% or less, it is possible to ensure a sufficient distance between the glassy carbon particles and the graphite particles constituting the graphite base material. Therefore, it is possible to effectively prevent the occurrence of distortion due to the difference in physical properties between glassy carbon and graphite.
（４）前記コア領域の気孔率が１２～２５％である。 (4) The core region has a porosity of 12 to 25%.
コア領域の気孔率が１２％以上であると、気孔内部にガラス状カーボンの粒子が充填された際に、ガラス状カーボンの粒子と黒鉛基材を構成する黒鉛粒子との間に十分な距離を確保することができる。その結果、発生する内部応力を小さくし、高温に長時間曝された場合であっても、クリープ変形を生じにくくすることができる。コア領域の気孔率が２５％以下であると、黒鉛基材自体の強度が十分に確保できるので、ガラス状カーボンの粒子を表面から脱落しにくくすることができる。 When the porosity of the core region is 12% or more, when the pores are filled with glassy carbon particles, there is a sufficient distance between the glassy carbon particles and the graphite particles constituting the graphite base material. can be secured. As a result, the generated internal stress can be reduced, making it difficult for creep deformation to occur even when exposed to high temperatures for a long time. When the porosity of the core region is 25% or less, sufficient strength of the graphite base material itself can be ensured, making it difficult for glassy carbon particles to fall off the surface.
また、前記課題を解決するための本発明に係る黒鉛材料の製造方法は、以下のとおりである。 Further, a method for manufacturing a graphite material according to the present invention for solving the above problems is as follows.
（５）気孔を含む黒鉛基材に難黒鉛化性の炭素前駆体の水溶液を含浸、乾燥、及び硬化する含浸工程と、前記黒鉛基材を焼成することにより、前記難黒鉛化性の炭素前駆体を炭素化し、前記黒鉛基材の表層における前記気孔の内部にガラス状カーボンの粒子が充填された封止層を形成する炭素化工程と、を含む黒鉛材料の製造方法。 (5) An impregnation step in which a graphite base material containing pores is impregnated with an aqueous solution of a non-graphitizable carbon precursor, dried, and hardened, and the graphite base material is fired to form the non-graphitizable carbon precursor. A method for producing a graphite material, comprising: carbonizing the graphite material and forming a sealing layer filled with glassy carbon particles inside the pores in the surface layer of the graphite base material.
黒鉛基材に難黒鉛化性の炭素前駆体を水溶液として含浸する。黒鉛は炭素のみからなり、水素結合がないので極性がなく、無極性溶媒との親和性が高く、水溶液のような極性溶媒との親和性は低い。したがって、黒鉛基材に対する水溶液の接触角は大きく、水溶液は黒鉛基材に含浸されにくい。すなわち、難黒鉛化性の炭素前駆体の水溶液５０を黒鉛基材内に含浸させようとすると、その浸み込みにくさ故に、小さな気孔よりも大きな気孔に対して選択的に含浸される（図１（ｂ）参照）。また、含浸された難黒鉛化性の炭素前駆体が焼成され、ガラス状カーボンとなる炭素化の過程においては、図２（ｃ）のように、黒鉛基材を構成する黒鉛粒子４０同士を接合するようにはガラス状カーボン６１が形成されにくい。難黒鉛化性の炭素前駆体は、その濡れ性の悪さから、図１（ｃ）のように、大きな気孔の内部で、黒鉛粒子４０に付着しにくく僅かに接触するのみで、独立したガラス状カーボンの粒子６０となるように炭素化する。このように、難黒鉛化性の炭素前駆体の水溶液５０が含浸された黒鉛基材の領域では、ガラス状カーボンの粒子６０が黒鉛基材の大きな気孔内に充填された封止層３０が形成される（図１（ａ）～図１（ｃ）参照）。
かかる製造方法により得られた黒鉛材料は、封止層に一定の厚みを持たせることができることから、当該封止層を形成した後、封止層に対して研磨等の加工を行った場合でも、ガラス状カーボンの粒子による封止層の効果を維持することができる。その結果、表面が平滑で寸法精度の高い黒鉛材料を得ることができる。
A graphite base material is impregnated with a non-graphitizable carbon precursor as an aqueous solution. Graphite consists only of carbon and has no hydrogen bonds, so it has no polarity and has a high affinity with nonpolar solvents, but a low affinity with polar solvents such as aqueous solutions. Therefore, the contact angle of the aqueous solution with respect to the graphite base material is large, and the graphite base material is hardly impregnated with the aqueous solution. In other words, when an aqueous solution 50 of a non-graphitizable carbon precursor is impregnated into a graphite base material, large pores are selectively impregnated rather than small pores due to the difficulty in impregnating the graphite base material (Fig. 1(b)). In addition, in the carbonization process in which the impregnated non-graphitizable carbon precursor is fired and becomes glassy carbon, graphite particles 40 constituting the graphite base material are bonded together, as shown in FIG. 2(c). In this case, glassy carbon 61 is difficult to form. Due to its poor wettability, the non-graphitizable carbon precursor is difficult to adhere to the graphite particles 40 inside the large pores and only slightly contacts them, forming independent glass-like particles. Carbonization is performed to form carbon particles 60. In this way, in the region of the graphite base material impregnated with the aqueous solution 50 of the non-graphitizable carbon precursor, a sealing layer 30 is formed in which the large pores of the graphite base material are filled with glassy carbon particles 60. (See FIGS. 1(a) to 1(c)).
Since the graphite material obtained by this manufacturing method allows the sealing layer to have a certain thickness, even if the sealing layer is processed such as polishing after forming the sealing layer. , the effect of the sealing layer due to glassy carbon particles can be maintained. As a result, a graphite material with a smooth surface and high dimensional accuracy can be obtained.
本発明に係る黒鉛材料の製造方法は、以下の態様であることが好ましい。 The method for producing a graphite material according to the present invention preferably has the following embodiments.
（６）前記含浸工程において、前記黒鉛基材を減圧状態で保持したのち 、前記難黒鉛化性の炭素前駆体の水溶液を加圧含浸させる。 (6) In the impregnation step, the graphite base material is held under reduced pressure and then impregnated with the aqueous solution of the non-graphitizable carbon precursor under pressure.
黒鉛基材と難黒鉛化性の炭素前駆体の水溶液とは、親和性が低いことから、黒鉛基材の気孔内部に当該水溶液が含浸されにくい。そのため、黒鉛基材を減圧状態に保持したのち、黒鉛基材の気孔内部に当該水溶液を加圧含浸することにより、大きな気孔から順に前記水溶液を容易に含浸することが可能となる。さらには、より内部の気孔にまで水溶液が含浸される。その結果、所望する十分な厚さの封止層を形成することができる。 Since the graphite base material and the aqueous solution of the non-graphitizable carbon precursor have low affinity, the aqueous solution is difficult to impregnate inside the pores of the graphite base material. Therefore, by holding the graphite base material in a reduced pressure state and then impregnating the inside of the pores of the graphite base material with the aqueous solution under pressure, it becomes possible to easily impregnate the aqueous solution in order from the largest pores. Furthermore, even the inner pores are impregnated with the aqueous solution. As a result, a sealing layer having a desired sufficient thickness can be formed.
（７）前記難黒鉛化性の炭素前駆体の水溶液の前記黒鉛基材に対する接触角は２０～６０°である。 (7) The contact angle of the aqueous solution of the non-graphitizable carbon precursor to the graphite base material is 20 to 60°.
難黒鉛化性の炭素前駆体の水溶液の黒鉛基材に対する接触角が２０°以上であると、難黒鉛化性の炭素前駆体の水溶液と黒鉛基材を構成する黒鉛粒子との親和性は十分に小さいと言える。すなわち、当該水溶液の、黒鉛基材の気孔内部への浸透力は弱く、黒鉛粒子との接合力が弱い。そのため、含浸工程後、含浸された難黒鉛化性の炭素前駆体が収縮し（例えば熱硬化性樹脂が熱硬化し）、黒鉛粒子と接合することなく独立して、粒子状のガラス状カーボンが形成されやすい。また、接触角が６０°以下であると、加圧含浸によって、黒鉛基材の気孔に難黒鉛化性の炭素前駆体の水溶液を容易に含浸させることができ、所望の厚さの封止層を形成することが容易となる。 When the contact angle of the aqueous solution of the non-graphitizable carbon precursor to the graphite base material is 20° or more, the aqueous solution of the non-graphitizable carbon precursor has sufficient affinity with the graphite particles constituting the graphite base material. It can be said that it is small. That is, the permeability of the aqueous solution into the pores of the graphite base material is weak, and the bonding force with graphite particles is weak. Therefore, after the impregnation process, the impregnated non-graphitizable carbon precursor shrinks (for example, the thermosetting resin is thermoset), and particulate glassy carbon is formed independently without bonding with the graphite particles. easy to form. In addition, when the contact angle is 60° or less, the pores of the graphite base material can be easily impregnated with the aqueous solution of the non-graphitizable carbon precursor by pressurized impregnation, and the sealing layer can have a desired thickness. It becomes easy to form.
（８）前記難黒鉛化性の炭素前駆体の水溶液の粘度は１～１００ｍＰａ・ｓである。 (8) The viscosity of the aqueous solution of the non-graphitizable carbon precursor is 1 to 100 mPa·s.
難黒鉛化性の炭素前駆体の水溶液の粘度を１ｍＰａ・ｓ以上とすることにより、水溶液中の難黒鉛化性の炭素前駆体（溶質）の濃度を高くすることができる。そのため、より多くの難黒鉛化性の炭素前駆体を、効率良く黒鉛基材の気孔の内部に含浸することができる。また、粘度を１００ｍＰａ・ｓ以下とすることにより、黒鉛基材の適度な深さにまで難黒鉛化性の炭素前駆体の水溶液を含浸させることができ、所望する十分な厚さの封止層を形成することができる。 By setting the viscosity of the aqueous solution of the non-graphitizable carbon precursor to 1 mPa·s or more, the concentration of the non-graphitizable carbon precursor (solute) in the aqueous solution can be increased. Therefore, more of the non-graphitizable carbon precursor can be efficiently impregnated into the pores of the graphite base material. In addition, by setting the viscosity to 100 mPa・s or less, the graphite base material can be impregnated with the aqueous solution of the non-graphitizable carbon precursor to an appropriate depth, and the desired sufficient thickness of the sealing layer can be obtained. can be formed.
（９）前記難黒鉛化性の炭素前駆体は熱硬化性樹脂である。 (9) The non-graphitizable carbon precursor is a thermosetting resin.
難黒鉛化性の炭素前駆体が熱硬化性樹脂であると、炭素化の前に樹脂を熱硬化させることで、黒鉛粒子と接合することなく独立して、粒子状の硬化した樹脂を形成することができる。これにより、次いで行われる炭素化で、同様の粒子状のガラス状カーボンを形成しやすい。 When the non-graphitizable carbon precursor is a thermosetting resin, by thermosetting the resin before carbonization, a particulate hardened resin can be formed independently without being bonded to graphite particles. be able to. This makes it easier to form similar particulate glassy carbon in the subsequent carbonization.
（１０）前記含浸工程の前の前記黒鉛基材は、気孔率が１２～２５％である。 (10) The graphite base material before the impregnation step has a porosity of 12 to 25%.
含浸工程の前の黒鉛基材の気孔率が１２％以上であると、黒鉛基材を構成する黒鉛粒子と黒鉛粒子との間に十分な距離（空隙）が確保され、発生する内部応力を小さくできることから、クリープ変形をより生じにくくすることができる。また、ガラス状カーボンの粒子が黒鉛基材の気孔に充填された後も、ガラス状カーボンの粒子と黒鉛粒子との間に十分な距離が確保され、前記と同様、クリープ変形をより生じにくくすることができる。気孔率が２５％以下であると、黒鉛基材自体の強度を十分に確保できるので、ガラス状カーボンの粒子が表面から脱落しにくくすることができる。 When the porosity of the graphite base material before the impregnation process is 12% or more, a sufficient distance (void) is secured between the graphite particles constituting the graphite base material, reducing the internal stress that occurs. As a result, creep deformation can be made more difficult to occur. Furthermore, even after the glassy carbon particles are filled into the pores of the graphite base material, a sufficient distance is maintained between the glassy carbon particles and the graphite particles, making creep deformation more difficult to occur as described above. be able to. When the porosity is 25% or less, sufficient strength of the graphite base material itself can be ensured, so that glassy carbon particles can be prevented from falling off from the surface.
本発明に係る黒鉛材料によれば、黒鉛基材の表層にガラス状カーボンの粒子が充填された封止層が形成されることにより、大きな気孔を小さくする効果が強く効率良く気孔を封止することができる。また、黒鉛基材の気孔部分に独立してガラス状カーボンの粒子が存在しているため、黒鉛粒子とガラス状カーボンの粒子との物理的な接触が少なく、内部応力、歪みを生じさせにくく、クリープ変形が起こりにくい。 According to the graphite material according to the present invention, a sealing layer filled with glassy carbon particles is formed on the surface layer of the graphite base material, so that the effect of reducing large pores is strong and efficiently seals the pores. be able to. In addition, since the glassy carbon particles exist independently in the pores of the graphite base material, there is little physical contact between the graphite particles and the glassy carbon particles, making it difficult to generate internal stress or distortion. Creep deformation is less likely to occur.
（発明の詳細な説明）
（黒鉛材料）
本発明に係る黒鉛材料は、基体となる黒鉛基材が気孔を含み、コア領域と表層に位置する封止層とから構成され、前記封止層は、前記黒鉛基材の気孔の内部にガラス状カーボンの粒子が充填された層であることを特徴とする。
(Detailed description of the invention)
(graphite material)
In the graphite material according to the present invention, the graphite base material serving as the base material includes pores, and is composed of a core region and a sealing layer located on the surface layer, and the sealing layer has glass inside the pores of the graphite base material. It is characterized by a layer filled with shaped carbon particles.
ガラス状カーボンの粒子は、黒鉛基材の気孔の内部に充填される。すなわちガラス状カーボンは、図２（ｃ）のように黒鉛基材を構成する黒鉛粒子４０と黒鉛粒子４０とを結合するように形成されるのではなく、図１（ｃ）のように、黒鉛粒子４０と黒鉛粒子４０との間の大きな気孔（空隙）部分に、粒子として独立して存在する。すなわち、ガラス状カーボンの粒子６０は黒鉛粒子４０に付着するのではなく、わずかに接触するのみで独立して存在する。これにより、大きな気孔を小さくする効果が強く効率良く気孔を封止することができる。 Glassy carbon particles are filled inside the pores of the graphite substrate. In other words, the glassy carbon is not formed so as to bond the graphite particles 40 constituting the graphite base material as shown in FIG. 2(c), but rather as shown in FIG. The particles exist independently as particles in large pores (voids) between the particles 40 and the graphite particles 40 . That is, the glassy carbon particles 60 do not adhere to the graphite particles 40, but exist independently with only slight contact. Thereby, the effect of reducing the size of large pores is strong and the pores can be efficiently sealed.
また、ガラス状カーボンが粒子として気孔部分に充填されているため、黒鉛粒子とガラス状カーボンの粒子との物理的な接触が少なく、ガラス状カーボンの粒子と黒鉛粒子との間で内部応力、歪みを生じさせにくい構造となっている。これにより、充填されたガラス状カーボンの粒子に起因して発生する内部応力は小さく、高温環境下でクリープ変形を防ぐことができる。
さらに、黒鉛基材表面の極めて浅い表層部分だけでなく、所望する一定の深さにおける気孔の内部までガラス状カーボンの粒子を充填できるため、黒鉛材料の表面に摩耗が生じても、封止の効果を継続することができる。
In addition, because the pores are filled with glassy carbon as particles, there is little physical contact between the graphite particles and the glassy carbon particles, and internal stress and strain occur between the glassy carbon particles and graphite particles. The structure is such that it is difficult to cause this. As a result, the internal stress generated due to the filled glassy carbon particles is small, and creep deformation can be prevented in a high-temperature environment.
In addition, glassy carbon particles can be filled not only into the extremely shallow surface layer of the graphite base material surface, but also into the pores at a certain desired depth, so even if the surface of the graphite material is abraded, the sealing will continue. The effect can be continued.
本発明におけるガラス状カーボンの粒子は、黒鉛基材の表層における気孔に充填されていればよいが、黒鉛基材全体の気孔に充填されていてもよい。この場合には、コア領域が存在せず、黒鉛基材の全体が封止層ということになる。
また、黒鉛基材が平板状である場合、一方の面あるいは両面の表層に封止層が形成されていてもよい。さらに、黒鉛基材が平板状ではなく、直方体や球形等の立体的な形状である場合には、封止性が求められる領域の表層に、前記封止層が形成されていればよい。
The glassy carbon particles in the present invention may be filled in the pores in the surface layer of the graphite base material, but may be filled in the pores of the entire graphite base material. In this case, there is no core region, and the entire graphite base material is the sealing layer.
Moreover, when the graphite base material is flat, a sealing layer may be formed on the surface layer of one or both surfaces. Furthermore, when the graphite base material is not flat but has a three-dimensional shape such as a rectangular parallelepiped or a sphere, the sealing layer may be formed on the surface layer of the area where sealing properties are required.
封止層は、消耗や摩耗が生じる用途に黒鉛材料を用いた場合であっても、表面の気孔率が急激に変化しにくく、より安定した性能を維持することができることから、その厚さが１ｍｍ以上であることが好ましく、３ｍｍ以上がより好ましい。また、厚さの上限は特に限定されないが、発生する内部応力を小さくすることができ、高温下に長時間曝された場合であっても、クリープ変形を生じにくくすることができることから、その厚さは３０ｍｍ以下が好ましく、２０ｍｍ以下がより好ましい。さらに、黒鉛材料を溶融金属を注入する鋳型として用いる場合には、断面形状の寸法精度をさらに高くする点から、１０ｍｍ以下がさらに好ましい。
なお、封止層の厚さはガラス状カーボンの粒子の存在の有無と共に、偏光顕微鏡により求めることができる。ガラス状カーボンの粒子の存在は、偏光顕微鏡で確認したときに方向性がないので試料を回転しても色が変わらないことから容易に確認することができる。
Even when graphite material is used in applications where wear and tear occur, the sealing layer is difficult to change its surface porosity rapidly and can maintain more stable performance, so its thickness is It is preferably 1 mm or more, more preferably 3 mm or more. In addition, although there is no particular upper limit to the thickness, it is possible to reduce the internal stress that occurs and make it difficult for creep deformation to occur even when exposed to high temperatures for a long time. The length is preferably 30 mm or less, more preferably 20 mm or less. Further, when graphite material is used as a mold for injecting molten metal, the thickness is more preferably 10 mm or less in order to further increase the dimensional accuracy of the cross-sectional shape.
Note that the thickness of the sealing layer can be determined by using a polarizing microscope as well as the presence or absence of glassy carbon particles. The presence of glassy carbon particles can be easily confirmed by the fact that when observed using a polarizing microscope, the color does not change even when the sample is rotated because it has no directionality.
また、封止層が上記範囲の厚さである場合、黒鉛材料全体の厚みはおおよそ１０～１００ｍｍ程度が好ましい。 Further, when the sealing layer has a thickness within the above range, the thickness of the entire graphite material is preferably about 10 to 100 mm.
封止層の気孔率は、母材である黒鉛基材の気孔率等の影響を受けることから一概に規定できないが、黒鉛基材の気孔内部にガラス状カーボンの粒子が充填されるために、コア領域の気孔率よりも低い。ガラス状カーボンの粒子によって、流体の浸透を十分に遮ることができ、特に鋳型として用いた場合には、反応性のガスや溶融金属との反応をより防止できることから、封止層の気孔率とコア領域の気孔率との差は、１．０％以上であることが好ましく、１．５％以上であることがより好ましい。また、ガラス状カーボンの粒子と黒鉛基材を構成する黒鉛粒子との間に十分な距離を確保することができ、ガラス状カーボンと黒鉛との物性差に起因する歪みの発生をより防止できることから、封止層の気孔率と、コア領域の気孔率との差は５．０％以下であることが好ましく、３．０％以下であることがより好ましい。なお、封止層の気孔率とコア領域の気孔率との差は、黒鉛基材の気孔に充填されたガラス状カーボンの充填率と読みかえることができる。また、コア領域が存在せず、すべて封止層である場合には、コア領域の気孔率とは、ガラス状カーボンの粒子が充填される前の黒鉛基材の気孔率と読み替えることができる。
なお、コア領域の気孔率は水銀圧入法により求めることができる。また、同様に封止層の気孔率は水銀圧入法により求めることができるが、封止層の気孔率が測定できるようコア領域を取り除いて封止層のみを残すように加工した後に測定する。水銀圧入法では、２００ＭＰａまで加圧して圧入された水銀の容積から算出することができる。
The porosity of the sealing layer cannot be determined unconditionally because it is affected by the porosity of the graphite base material, but since the pores of the graphite base material are filled with glassy carbon particles, lower than the porosity of the core region. Glassy carbon particles can sufficiently block the penetration of fluid, and especially when used as a mold, they can further prevent reactions with reactive gases and molten metal, so the porosity of the sealing layer and The difference from the porosity of the core region is preferably 1.0% or more, more preferably 1.5% or more. In addition, it is possible to secure a sufficient distance between the glassy carbon particles and the graphite particles constituting the graphite base material, making it possible to further prevent the occurrence of distortion due to the physical property difference between glassy carbon and graphite. The difference between the porosity of the sealing layer and the porosity of the core region is preferably 5.0% or less, more preferably 3.0% or less. Note that the difference between the porosity of the sealing layer and the porosity of the core region can be read as the filling rate of glassy carbon filled in the pores of the graphite base material. Further, in the case where there is no core region and all the layers are sealing layers, the porosity of the core region can be read as the porosity of the graphite base material before being filled with glassy carbon particles.
Note that the porosity of the core region can be determined by mercury intrusion method. Similarly, the porosity of the sealing layer can be determined by the mercury intrusion method, but in order to measure the porosity of the sealing layer, the core region is removed and only the sealing layer is processed after processing. In the mercury intrusion method, it can be calculated from the volume of mercury injected under pressure up to 200 MPa.
コア領域の気孔率は、１２％以上が好ましく、１４％以上がより好ましい。コア領域の気孔率が、上記範囲であると、気孔内部にガラス状カーボンの粒子が充填された際に、ガラス状カーボンの粒子と黒鉛基材を構成する黒鉛粒子との間に十分な距離を確保することができ、その結果、発生する内部応力を小さくし、高温に長時間曝された場合であっても、クリープ変形を生じにくくすることができる。また、コア領域の気孔率は２５％以下が好ましく、２０％以下がより好ましい。コア領域の気孔率が上記範囲であると、黒鉛基材自体の強度が十分に確保できるので、ガラス状カーボンの粒子を表面から脱落しにくくすることができる。 The porosity of the core region is preferably 12% or more, more preferably 14% or more. When the porosity of the core region is within the above range, when the pores are filled with glassy carbon particles, there is a sufficient distance between the glassy carbon particles and the graphite particles constituting the graphite base material. As a result, the generated internal stress can be reduced, and creep deformation can be made less likely to occur even when exposed to high temperatures for a long time. Further, the porosity of the core region is preferably 25% or less, more preferably 20% or less. When the porosity of the core region is within the above range, sufficient strength of the graphite base material itself can be ensured, making it difficult for glassy carbon particles to fall off the surface.
（黒鉛材料の製造方法）
本発明に係る黒鉛材料の製造方法は、気孔を含む黒鉛基材に難黒鉛化性の炭素前駆体の水溶液を含浸し、乾燥および硬化する含浸工程と、前記黒鉛基材を焼成することにより、前記難黒鉛化性の炭素前駆体を炭素化し、前記黒鉛基材の表層における前記気孔の内部にガラス状カーボンの粒子が充填された封止層を形成する炭素化工程と、をこの順に含む。
(Method for manufacturing graphite material)
The method for producing a graphite material according to the present invention includes an impregnation step of impregnating a graphite base material containing pores with an aqueous solution of a non-graphitizable carbon precursor, drying and hardening the graphite base material, and firing the graphite base material. The method includes, in this order, a carbonization step of carbonizing the non-graphitizable carbon precursor to form a sealing layer filled with glassy carbon particles inside the pores in the surface layer of the graphite base material.
図１（ａ）に示すように、黒鉛基材を構成する黒鉛粒子４０と黒鉛粒子４０との間には気孔が存在する。含浸工程では、図１（ａ）及び図１（ｂ）に示すように、当該気孔部分に、難黒鉛化性の炭素前駆体の水溶液５０を含浸させる。このとき、黒鉛基材を構成する黒鉛粒子４０は、炭素のみからなり水素結合がないことから極性がなく、無極性溶媒との親和性が高い。すなわち、極性を有する難黒鉛化性の炭素前駆体の水溶液５０との親和性は低い。このため、極性を有する難黒鉛化性の炭素前駆体の水溶液５０の黒鉛粒子４０に対する接触角は大きく（濡れ性は低く）なり、難黒鉛化性の炭素前駆体の水溶液５０は黒鉛基材の気孔に含浸されにくい。このような性質を有する黒鉛基材に難黒鉛化性の炭素前駆体の水溶液５０を含浸させると、その浸み込みにくさ故に、小さな気孔よりも大きな気孔に対して、選択的に含浸されることとなる。 As shown in FIG. 1(a), pores exist between the graphite particles 40 constituting the graphite base material. In the impregnation step, as shown in FIGS. 1A and 1B, the pores are impregnated with an aqueous solution 50 of a non-graphitizable carbon precursor. At this time, the graphite particles 40 constituting the graphite base material are made only of carbon and have no hydrogen bonds, so they have no polarity and have high affinity with nonpolar solvents. That is, the affinity of the polar, non- graphitizable carbon precursor with the aqueous solution 50 is low. Therefore, the contact angle of the polar aqueous solution 50 of the non-graphitizable carbon precursor with respect to the graphite particles 40 becomes large (wetting property is low), and the aqueous solution 50 of the non-graphitizable carbon precursor has a large contact angle with respect to the graphite particles 40. Not easily impregnated into pores. When a graphite base material having such properties is impregnated with an aqueous solution 50 of a non-graphitizable carbon precursor, large pores are selectively impregnated rather than small pores due to its difficulty in penetrating. It happens.
含浸工程の前の黒鉛基材の好ましい気孔率は、前記（黒鉛基材）の項目における「コア領域の気孔率」と同様、１２％以上が好ましく、１４％以上がより好ましく、また、２５％以下が好ましく、２０％以下がより好ましい。 The preferable porosity of the graphite base material before the impregnation step is preferably 12% or more, more preferably 14% or more, and 25% or more, similar to the "porosity of the core region" in the item (graphite base material) above. It is preferably at most 20%, more preferably at most 20%.
難黒鉛化性の炭素前駆体の水溶液と黒鉛基材との親和性が十分に小さいと、含浸工程後、気孔の内部で難黒鉛化性の炭素前駆体が収縮し（例えば熱硬化性樹脂が熱硬化し）、炭素化する際、黒鉛粒子と接合することなく独立して、粒子状のガラス状カーボンが形成されやすい。親和性を表す指標として、難黒鉛化性の炭素前駆体の水溶液の黒鉛基材に対する接触角は２０°以上が好ましい。また、黒鉛基材の気孔内への難黒鉛化性の炭素前駆体の水溶液の含浸のさせやすさから、接触角は６０°以下が好ましい。これにより、十分な厚さの封止層を形成することが容易となる。
難黒鉛化性の炭素前駆体の水溶液の黒鉛基材に対する接触角は、水溶液を黒鉛基材上に滴下して側面から観察し、当該水溶液の液滴と黒鉛基材との角度を実測して求めることができる。
If the affinity between the aqueous solution of the non-graphitizable carbon precursor and the graphite substrate is sufficiently small, the non-graphitizable carbon precursor will shrink inside the pores after the impregnation process (for example, the thermosetting resin will shrink). During carbonization, particulate glassy carbon tends to be formed independently without being bonded to graphite particles. As an indicator of affinity, the contact angle of an aqueous solution of a non-graphitizable carbon precursor to a graphite base material is preferably 20° or more. Further, the contact angle is preferably 60° or less in order to facilitate the impregnation of the aqueous solution of the non-graphitizable carbon precursor into the pores of the graphite base material. This makes it easy to form a sealing layer with sufficient thickness.
The contact angle of an aqueous solution of a non-graphitizable carbon precursor to a graphite substrate is determined by dropping the aqueous solution onto the graphite substrate, observing it from the side, and actually measuring the angle between the droplet of the aqueous solution and the graphite substrate. You can ask for it.
同様に、黒鉛基材の気孔内への難黒鉛化性の炭素前駆体の水溶液の含浸させやすさ、すなわち、十分な厚さの封止層を容易に形成する点から、難黒鉛化性の炭素前駆体の水溶液の粘度は１００ｍＰａ・ｓ以下が好ましく、５０ｍＰａ・ｓ以下がより好ましい。
また、難黒鉛化性の炭素前駆体の水溶液における溶質（難黒鉛化性の炭素前駆体）の濃度を高くし、より多くのガラス状カーボンの粒子を効率よく形成させる点から、難黒鉛化性の炭素前駆体の水溶液の粘度は１ｍＰａ・ｓ以上が好ましく、５ｍＰａ・ｓ以上がより好ましい。
Similarly, from the viewpoint of ease of impregnation of an aqueous solution of a non-graphitizable carbon precursor into the pores of a graphite base material, that is, easy formation of a sufficiently thick sealing layer, The viscosity of the aqueous solution of the carbon precursor is preferably 100 mPa·s or less, more preferably 50 mPa·s or less.
In addition, the concentration of solute (non-graphitizable carbon precursor) in the aqueous solution of non-graphitizable carbon precursor is increased to efficiently form more glassy carbon particles. The viscosity of the aqueous solution of the carbon precursor is preferably 1 mPa·s or more, more preferably 5 mPa·s or more.
難黒鉛化性の炭素前駆体の水溶液における難黒鉛化性の炭素前駆体の濃度は、水溶液の粘度が前記好ましい範囲となるように調整することが好ましい。また、難黒鉛化性の炭素前駆体の水溶液は、従来公知の方法により調製することができる。 The concentration of the non-graphitizable carbon precursor in the aqueous solution of the non-graphitizable carbon precursor is preferably adjusted so that the viscosity of the aqueous solution falls within the preferred range. Further, an aqueous solution of a non-graphitizable carbon precursor can be prepared by a conventionally known method.
難黒鉛化性の炭素前駆体は炭素化によりガラス状カーボンとなる前駆体であり、水溶液として黒鉛基材の気孔内へ含浸させることから、水溶性の前駆体が好ましく、また、焼成過程で軟化による変形を防止する点から水溶性の熱硬化性樹脂がより好ましく、水溶性フェノール樹脂または水溶性フラン樹脂がさらに好ましい。 The non-graphitizable carbon precursor is a precursor that becomes glassy carbon by carbonization, and since it is impregnated into the pores of the graphite base material as an aqueous solution, a water-soluble precursor is preferable, and it softens during the firing process. A water-soluble thermosetting resin is more preferable from the viewpoint of preventing deformation caused by the resin, and a water-soluble phenol resin or a water-soluble furan resin is even more preferable.
含浸工程は、黒鉛基材を減圧状態で保持したのち、難黒鉛化性の炭素前駆体の水溶液を加圧含浸させることが好ましい。これにより、黒鉛基材の大きな気孔から順に、より深い部分に位置する気孔の内部まで、難黒鉛化性の炭素前駆体の水溶液を含浸させることができる。具体的には、例えば、黒鉛基材を真空引きし、黒鉛基材を難黒鉛化性の炭素前駆体の水溶液に浸漬する。そして、常圧に戻す等、加圧することにより黒鉛基材の表面から一定の深さまで、黒鉛基材の気孔に難黒鉛化性の炭素前駆体の水溶液を含浸することができる。 In the impregnation step, it is preferable to hold the graphite base material under reduced pressure and then impregnate it with an aqueous solution of a non-graphitizable carbon precursor under pressure. Thereby, the aqueous solution of the non-graphitizable carbon precursor can be impregnated into the interior of the pores located in deeper parts in order from the larger pores of the graphite base material. Specifically, for example, the graphite base material is evacuated, and the graphite base material is immersed in an aqueous solution of a non-graphitizable carbon precursor. Then, by applying pressure such as returning to normal pressure, the pores of the graphite base material can be impregnated with an aqueous solution of a non-graphitizable carbon precursor to a certain depth from the surface of the graphite base material.
次いで、得られた黒鉛基材を乾燥、硬化することにより難黒鉛化性の炭素前駆体の含浸を完了させる。 Next, the obtained graphite base material is dried and cured to complete impregnation with the non-graphitizable carbon precursor.
乾燥の温度や時間は特に限定されないが、黒鉛基材の気孔内に含浸された難黒鉛化性の炭素前駆体が流出しないように乾燥させる。これは、気孔内部の水蒸気圧が雰囲気より大きくなると、水蒸気圧で難黒鉛化性の炭素前駆体が噴出するおそれがあるためである。
乾燥条件は、難黒鉛化性の炭素前駆体の種類によっても異なるが、水溶性の熱硬化性樹脂を用いる場合には、例えば、４０℃程度から徐々に温度を上昇させ、熱硬化性樹脂が硬化しない程度の温度、例えば１２０℃程度で終了させてもよい。
Although the drying temperature and time are not particularly limited, drying is performed so that the non-graphitizable carbon precursor impregnated into the pores of the graphite base material does not flow out. This is because if the water vapor pressure inside the pores becomes higher than the atmosphere, there is a risk that the non-graphitizable carbon precursor will be ejected due to the water vapor pressure.
Drying conditions vary depending on the type of non-graphitizable carbon precursor, but when using a water-soluble thermosetting resin, for example, the temperature is gradually raised from about 40°C to dry the thermosetting resin. The process may be completed at a temperature that does not cause curing, for example, about 120°C.
難黒鉛化性の炭素前駆体が熱硬化性樹脂である場合、前記乾燥に次いで、樹脂を硬化させる。硬化は通常、熱を加えることによる熱硬化を行う。熱硬化の過程で、水溶性の熱硬化性樹脂は黒鉛との親和性が低いことに起因して、黒鉛基材を構成する黒鉛粒子同士を接合するように硬化するのではなく、黒鉛基材の気孔部分の中心で、独立して粒子状に収縮していく。これにより、次ぐ焼成による炭素化工程を経ると、黒鉛基材の気孔の内部にガラス状カーボンの粒子が形成されやすくなる。
硬化条件は、熱硬化性樹脂の種類によっても異なるが、例えば（水溶性）フェノール樹脂を用いる場合には、１５０～２００℃で硬化させることが好ましい。
なお、難黒鉛化性の炭素前駆体として熱硬化性樹脂ではなく、熱硬化性樹脂のモノマーを含む水溶液を用いることも可能である。その場合には、黒鉛基材の気孔内へ当該モノマーの水溶液を含浸させ、乾燥、重合、硬化した後に、次いで行われる焼成に供することもできる。
When the non-graphitizable carbon precursor is a thermosetting resin, the resin is cured after the drying. Curing is usually carried out by applying heat. During the thermosetting process, the water-soluble thermosetting resin has a low affinity with graphite, so it does not harden to bond the graphite particles that make up the graphite base material, but instead hardens to bond the graphite particles that make up the graphite base material. At the center of the pores, they contract independently into particles. As a result, glassy carbon particles are likely to be formed inside the pores of the graphite base material through the subsequent carbonization step by firing.
Curing conditions vary depending on the type of thermosetting resin, but for example, when using a (water-soluble) phenol resin, it is preferable to cure at 150 to 200°C.
Note that it is also possible to use an aqueous solution containing a thermosetting resin monomer instead of a thermosetting resin as the non-graphitizable carbon precursor. In that case, an aqueous solution of the monomer can be impregnated into the pores of the graphite base material, dried, polymerized, and hardened, and then subjected to firing.
難黒鉛化性の炭素前駆体を硬化させた後、次いで焼成を行う炭素化工程により、難黒鉛化性の炭素前駆体を炭素化し、ガラス状カーボンの粒子が充填された封止層３０が形成される。
図２（ｃ）に示すように、極性の低い難黒鉛化性の炭素前駆体の溶液５１を用いた場合には、黒鉛粒子４０同士を接合するようにガラス状カーボン６１が形成される。これに対し、極性を有し、黒鉛との親和性が低い難黒鉛化性の炭素前駆体の水溶液５０を用いると、図１（ｃ）に示すように、ガラス状カーボンは黒鉛粒子４０同士を接合するように付着するのではなく、一部が黒鉛粒子４０と接触するのみで（図示せず）、ガラス状カーボンの粒子６０として独立して形成される。これは、難黒鉛化性の炭素前駆体の水溶液５０の、黒鉛粒子４０に対する濡れ性の低さに起因するものと考えられる。このようにして、難黒鉛化性の炭素前駆体の水溶液５０が含浸された領域では、ガラス状カーボンの粒子６０が黒鉛基材の気孔の内部に充填され、封止層３０が形成される。
After the non-graphitizable carbon precursor is cured, the non-graphitizable carbon precursor is carbonized through a carbonization process in which firing is performed, and a sealing layer 30 filled with glassy carbon particles is formed. be done.
As shown in FIG. 2C, when a solution 51 of a carbon precursor with low polarity and non-graphitizability is used, glassy carbon 61 is formed so as to bond the graphite particles 40 together. On the other hand, when an aqueous solution 50 of a non-graphitizable carbon precursor that has polarity and low affinity for graphite is used, glassy carbon forms graphite particles 40 that bind to each other, as shown in FIG. 1(c). They do not adhere to each other in a bonding manner, but only partially contact the graphite particles 40 (not shown), and are formed independently as glassy carbon particles 60. This is considered to be due to the low wettability of the aqueous solution 50 of the non-graphitizable carbon precursor to the graphite particles 40. In this manner, in the region impregnated with the aqueous solution 50 of the non-graphitizable carbon precursor, the glassy carbon particles 60 are filled into the pores of the graphite base material, and the sealing layer 30 is formed.
炭素化工程における焼成温度は、十分に揮発分が除かれていることが好ましく、例えば７００～１５００℃である。また窒素雰囲気下で焼成することが好ましい。 The firing temperature in the carbonization step is preferably 700 to 1500° C. to sufficiently remove volatile components. Moreover, it is preferable to bake in a nitrogen atmosphere.
かかる製造方法により得られた黒鉛材料は、封止層に一定の厚みを持たせることができることから、当該封止層を形成した後、封止層に対して研磨等の加工を行った場合でも、ガラス状カーボンの粒子による封止層の効果を維持することができる。その結果、表面が平滑で寸法精度の高い黒鉛材料を得ることができる。 Since the graphite material obtained by this manufacturing method allows the sealing layer to have a certain thickness, even if the sealing layer is processed such as polishing after forming the sealing layer. , the effect of the sealing layer due to glassy carbon particles can be maintained. As a result, a graphite material with a smooth surface and high dimensional accuracy can be obtained.
（発明を実施するための形態）
以下、本発明を実施例によって説明するが、本発明はこれらにより限定されるものではない。
（実施例１）
＜含浸工程＞
気孔を含む黒鉛（イビデン株式会社製、ＥＴ－１０、１００×１００×５０ｍｍ、気孔率１９．０％、かさ密度１．７７ｇ／ｃｍ３）を黒鉛基材として用いた。真空引きにより減圧状態を保った黒鉛基材を、難黒鉛化性の炭素前駆体である水溶性フェノール樹脂の水溶液に浸漬し、復圧することで大気圧まで加圧し当該水溶液を黒鉛基材に含浸させた。当該水溶液の黒鉛基材に対する接触角は３０°であり、水溶液の粘度は１０ｍＰａ・ｓであった。なお気孔率はＴｈｅｒｍｏ Ｆｉｓｈｅｒ Ｓｃｉｅｎｔｉｆｉｃ社製水銀圧入式気孔分布測定器ｐａｓｃａｌ ２４０を用いて２００ＭＰａまで加圧して測定した。
(Form for carrying out the invention)
EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited thereto.
(Example 1)
<Impregnation process>
Graphite containing pores (manufactured by IBIDEN Corporation, ET-10, 100×100×50 mm, porosity 19.0%, bulk density 1.77 g/cm 3 ) was used as the graphite base material. The graphite base material, which has been kept under reduced pressure by vacuuming, is immersed in an aqueous solution of water-soluble phenol resin, which is a non-graphitizable carbon precursor, and the pressure is restored to atmospheric pressure, and the aqueous solution is impregnated into the graphite base material. I let it happen. The contact angle of the aqueous solution with respect to the graphite base material was 30°, and the viscosity of the aqueous solution was 10 mPa·s. The porosity was measured using a mercury intrusion type porosity measuring device Pascal 240 manufactured by Thermo Fisher Scientific under pressure of up to 200 MPa.
次いで黒鉛基材を乾燥した。乾燥の温度は、水蒸気圧でフェノール樹脂が噴出しないように、４０℃程度から徐々に温度を上昇させ１２０℃程度で終了させた。続いて、さらに熱を加えてフェノール樹脂を熱硬化させた。熱硬化は２００℃で３時間保持することで行った。 The graphite substrate was then dried. The drying temperature was gradually increased from about 40° C. and ended at about 120° C. so that the phenol resin would not blow out due to water vapor pressure. Subsequently, heat was further applied to thermally cure the phenolic resin. Heat curing was performed by holding at 200°C for 3 hours.
＜炭素化工程＞
次に黒鉛基材を窒素雰囲気下、９００℃で２時間焼成し、炭素化を行った。これにより、黒鉛基材の気孔の内部にガラス状カーボンの粒子が充填された封止層を有する黒鉛材料を得た。封止層の厚みは２０ｍｍであり、その気孔率は１７．３％、かさ密度は１．７９ｇ／ｃｍ３であった。なお、気孔率は前記と同様の条件により水銀圧入法で測定した。
得られた黒鉛材料の偏光顕微鏡写真を図３、炭素前駆体を含浸する前の黒鉛基材の偏光顕微鏡写真を図４にそれぞれ示す。炭素前駆体を含浸する前の黒鉛基材と比較し、封止層部分では気孔の内部にガラス状カーボンの粒子６０が充填されていることを確認することができる。また、図３では所々大きな気孔が存在する。これは気孔の内部に存在したと考えられるガラス状カーボンの粒子が、偏光顕微鏡観察をする過程で脱落してしまったためと考えられる。
<Carbonization process>
Next, the graphite base material was fired at 900° C. for 2 hours in a nitrogen atmosphere to perform carbonization. As a result, a graphite material having a sealing layer in which glassy carbon particles were filled inside the pores of the graphite base material was obtained. The thickness of the sealing layer was 20 mm, the porosity was 17.3%, and the bulk density was 1.79 g/cm 3 . The porosity was measured by mercury porosimetry under the same conditions as above.
A polarized light micrograph of the obtained graphite material is shown in FIG. 3, and a polarized light micrograph of the graphite base material before being impregnated with the carbon precursor is shown in FIG. In comparison with the graphite base material before being impregnated with the carbon precursor, it can be confirmed that glassy carbon particles 60 are filled inside the pores in the sealing layer portion. Moreover, in FIG. 3, large pores are present in some places. This is thought to be because glassy carbon particles that were thought to have existed inside the pores fell off during the polarizing microscope observation process.
（比較例１）
実施例１と同様に、気孔を含む黒鉛材料（イビデン株式会社製、ＥＴ－１０、かさ密度１．７７ｇ／ｃｍ３）を用い、難黒鉛化性の炭素前駆体に代えて易黒鉛化性のピッチを含浸し、焼成、黒鉛化して、黒鉛基材を得た。なお、ピッチは有機物であり親和性が高いことから、黒鉛材料に速やかに浸透する。得られた黒鉛基材は気孔率が１６．０％、かさ密度が１．８５ｇ／ｃｍ３であった。比較例１の黒鉛基材の断面の偏光顕微鏡写真を図５に示す。実施例１と比較し、気孔の量は少なくなっていることが確認されるが、当該気孔の内部に粒子状の充填物は確認されなかった。
(Comparative example 1)
As in Example 1, a graphite material containing pores (manufactured by Ibiden Corporation, ET-10, bulk density 1.77 g/cm 3 ) was used, and an easily graphitizable carbon precursor was used in place of the non-graphitizable carbon precursor. A graphite base material was obtained by impregnating pitch, firing and graphitizing. Note that since pitch is an organic substance and has a high affinity, it quickly penetrates into the graphite material. The obtained graphite base material had a porosity of 16.0% and a bulk density of 1.85 g/cm 3 . A polarized light micrograph of a cross section of the graphite base material of Comparative Example 1 is shown in FIG. Although it was confirmed that the amount of pores was reduced compared to Example 1, no particulate filler was observed inside the pores.
本発明に係る黒鉛材料によれば、その封止性や耐摩耗性等から、例えば連続鋳造ノズル等、溶融金属を注入する鋳型として非常に有用である。さらに、高温で使用しても内部応力に伴う変形が起こりにくいことから、長期間、寸法精度の高い鋳型として用いることができる。 The graphite material according to the present invention is very useful as a mold for pouring molten metal, such as a continuous casting nozzle, due to its sealing properties and wear resistance. Furthermore, even when used at high temperatures, deformation due to internal stress is unlikely to occur, so it can be used as a mold with high dimensional accuracy for a long period of time.
３０ 封止層
４０ 黒鉛粒子
５０ 難黒鉛化性の炭素前駆体の水溶液
５１ 極性の低い難黒鉛化性の炭素前駆体の溶液
６０ ガラス状カーボンの粒子
６１ ガラス状カーボン
30 Sealing layer 40 Graphite particles 50 Aqueous solution of non-graphitizable carbon precursor 51 Solution of low polarity non-graphitizable carbon precursor 60 Glassy carbon particles 61 Glassy carbon
Claims (11)
前記封止層は、前記黒鉛基材の気孔の内部にガラス状カーボンの独立して存在する粒子が充填された層である黒鉛材料。 The graphite base material that serves as the base contains pores and is composed of a core region and a sealing layer located on the surface layer,
The sealing layer is a graphite material that is a layer filled with independently existing particles of glassy carbon inside the pores of the graphite base material.
前記黒鉛基材を焼成することにより、前記難黒鉛化性の炭素前駆体を炭素化し、前記黒鉛基材の表層における前記気孔の内部にガラス状カーボンの粒子が独立して存在するように充填された封止層を形成する炭素化工程と、を含む黒鉛材料の製造方法。 an impregnation step of impregnating a graphite base material containing pores with an aqueous solution of a non-graphitizable carbon precursor, drying, and curing;
By firing the graphite base material, the non-graphitizable carbon precursor is carbonized, and glassy carbon particles are filled in the pores in the surface layer of the graphite base material so that they exist independently. and a carbonization step of forming a sealing layer.
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