WO2013075498A1 - 一种石墨烯铸体的铸造方法 - Google Patents

一种石墨烯铸体的铸造方法 Download PDF

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WO2013075498A1
WO2013075498A1 PCT/CN2012/078048 CN2012078048W WO2013075498A1 WO 2013075498 A1 WO2013075498 A1 WO 2013075498A1 CN 2012078048 W CN2012078048 W CN 2012078048W WO 2013075498 A1 WO2013075498 A1 WO 2013075498A1
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graphene
cast
cast body
casting
hydrothermal reaction
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French (fr)
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孙立涛
毕恒昌
尹奎波
徐峰
万能
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东南大学
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
    • C04B35/52—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbon, e.g. graphite
    • C04B35/522—Graphite
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/60—Aspects relating to the preparation, properties or mechanical treatment of green bodies or pre-forms
    • C04B2235/61—Mechanical properties, e.g. fracture toughness, hardness, Young's modulus or strength

Definitions

  • the present invention relates to a method of casting a graphene cast body. Background technique
  • Isostatic molding technology plays a vital role in the research and development of metals and ceramic materials (Bocanegra-bernal, MH Journal of Material Science 2004, 39, 6399; Biasini, V., Parasporo, M., Bel losi , A. Thin Sol id Fi lms 1997, 297, 207).
  • This technique allows the material powder to be extruded from various directions to obtain a high-density, high-strength entity (Kim, H. S. Journal of Material Processing Technology 2002, 123, 319).
  • Isostatic graphite is the direct application of this technology, which is isotropic.
  • the technical problem to be solved by the present invention is to provide a casting method of a graphene casting body, which has a simple process, can control the mechanical properties of the graphene casting body, and has good mechanical properties of the graphene casting body. .
  • a method for casting a graphene cast body comprising the steps of:
  • the graphene oxide dispersion having a concentration of 0.5 mg/ml to 7 mg/ml is poured into a cup in a hydrothermal reaction kettle, and The mixed solution of the pH range of 5. 5-11. 6;
  • step 101 The hydrothermal reaction vessel in step 101 is heated to 150 ° C - 350 ° C for 3 h - 48 h, and the mixed solution is formed into a wet graphene gel;
  • the wet graphene gel is taken out from the hydrothermal reaction vessel of the step 102, and dried in an environment of from 20 ° C to 70 ° C to obtain a graphene cast body.
  • the method for casting a graphene cast body further includes a step 104 high temperature annealing treatment, wherein the graphene cast in step 103 is placed in a tube furnace filled with nitrogen at 12°.
  • the rate of C/min is raised to 900 ° C and maintained for 60 min, then the heating is stopped, the tube furnace is cooled, and when the temperature of the tube furnace is lower than 350 ° C, the nitrogen gas is stopped, and the tube furnace is cooled to room temperature.
  • the shape of the graphene cast in the step 103 is determined by the shape of the cup in the hydrothermal reactor in step 101.
  • the shape of the graphene cast in step 103 is determined by the position at which the hydrothermal reactor in step 101 is placed.
  • the size of the graphene cast in the step 103 is determined by setting the concentration of the graphene oxide dispersion in the step 101, the volume of the graphene oxide dispersion in the step 101, or the hydrothermal reactor in the step 102. The volume is controlled.
  • the casting method is simple.
  • the casting method provided by the present invention comprises only three steps, and the graphene oxide can be reduced to agglomerated graphene cast by simply hydrothermal reduction.
  • Conventional isostatic graphite generally takes seven steps to complete and the process is complicated.
  • the casting method has a simple process.
  • the traditional process of making isostatic graphite requires the use of expensive equipment at a price of millions.
  • the casting method of the present invention only needs to use a hydrothermal reaction kettle, and the equipment is simple and inexpensive.
  • Graphene cast has good mechanical properties.
  • the compressive strength of the graphene cast body can be greatly improved by increasing the high temperature annealing treatment step.
  • the graphene cast body subjected to high temperature annealing can be twice as strong as the graphene cast without high temperature annealing.
  • the high temperature annealed graphene cast has a five-fold increase in compressive strength compared to conventional graphite.
  • the different compressive strength of the graphene cast body can be obtained by controlling the different pfH of the mixed solution of the step 1.
  • the pH of the mixed solution can be adjusted by adjusting the concentration or addition amount of the ammonia or sodium hydroxide in the step 1, or by adjusting the concentration or the amount of the graphene oxide dispersion.
  • the adjustment of the pH value of the mixed solution is convenient and simple, so the casting method can conveniently control the mechanical properties of the graphene cast body. 4. It is very convenient to control the size and shape of the graphene cast body.
  • the size of the graphene cast body can be controlled by changing the concentration of the graphene oxide dispersion, the volume of the graphene oxide dispersion, and the volume of the reactor. Increasing the concentration of the graphene oxide dispersion, the size of the obtained graphene cast body becomes larger; increasing the volume of the graphene oxide dispersion liquid, the size of the obtained graphene cast body becomes larger; increasing the volume of the hydrothermal reaction kettle, resulting in The size of the graphene cast body will become larger.
  • the shape of the graphene cast body is set by setting the shape of the cup in the hydrothermal reaction vessel or the position at which the hydrothermal reaction vessel is placed. This method sets the shape of the graphene cast body, which is simple and stable.
  • Figure 1 is a bar graph showing the compressive strength of the corresponding graphene casts with different pfH in the mixed solution without the high temperature annealing step.
  • Figure 2 is a bar graph showing the compressive strength of the corresponding graphene cast by increasing the pH of the mixed solution at the high temperature annealing step.
  • each cylinder represents the average value of the compressive strength
  • the upper end of the I-shaped part at the upper part of each cylinder represents the maximum value of the compressive strength
  • the lower end of the working type represents the minimum compressive strength. value.
  • a casting method of a graphene cast body of the present invention comprising the following steps:
  • the pH range is 5. 5-11.
  • the pH is in the range of 5. 5-11.
  • the pH is in the range of 5. 5-11. 6 mixed solution.
  • the pH of the mixed solution is preferably in the range of 8.5 to 10.1, that is, when the mixed solution is a weakly alkaline solution, it has strong mechanical properties.
  • step 101 The hydrothermal reaction vessel in step 101 is heated to 150 ° C - 350 ° C for 3 h - 48 h, and the mixed solution forms a wet graphene gel.
  • the hydrothermal reactor is preferably heated between 150 and 280 °C.
  • the wet graphene gel is taken out from the hydrothermal reaction vessel of the step 102, and dried in an environment of from 20 ° C to 70 ° C to obtain a graphene cast body.
  • the method for casting a graphene cast body further includes a step 104 high temperature annealing treatment, wherein the high temperature annealing treatment is the graphene cast body in step 103, that is, the dried graphene cast body.
  • the high temperature annealing treatment is the graphene cast body in step 103, that is, the dried graphene cast body.
  • the nitrogen gas is stopped, mainly to save nitrogen.
  • the process of lowering the temperature of the tube furnace from 900 ° to room temperature no artificial intervention was applied and the tube furnace itself cooled in the atmosphere.
  • Graphene casts subjected to high temperature annealing have good mechanical properties.
  • the shape of the graphene cast in step 103 can be determined by the position or internal configuration of the hydrothermal reactor in step 101.
  • the shape of the graphene cast in the step 103 is determined by the shape of the cup in the hydrothermal reactor in step 101.
  • the graphene cast body in step 103 is a graphene sphere; when the inner cup of the hydrothermal reaction kettle in step 101 is a triangular prism, in step 103
  • the graphene cast body is a graphene triangular prism; when the inner cup of the hydrothermal reaction kettle in step 101 is a quadrangular prism shape, the graphene cast body in step 103 is a graphene quadrangular prism; when the water is hot in step 101
  • the graphene cast body in step 103 is a graphene gear; when the wall surface of the inner cup of the hydrothermal reaction kettle in step 101 is spiraled, the step 103
  • the graphene cast body is a graphene spiral.
  • the shape of the graphene cast in step 103 is determined by the position at which the hydrothermal reactor in step 101 is placed.
  • the graphene cast body in step 103 is a cylinder; when the hydrothermal reaction kettle in step 101 is placed horizontally, the graphene cast in step 103 is half Cylinder;
  • the graphene cast in step 103 is a cylinder having a trapezoidal cross section.
  • the hydrothermal reaction kettle in step 101 is placed upright, and a cylinder is disposed in the center of the inner cup of the hydrothermal reaction kettle; when the cylinder passes through the dispersion liquid in the inner cup In the surface, the graphene cast in step 103 is a hollow cylinder; when the dispersion in the inner cup covers the cylinder, the graphene cast in step 103 is graphene germanium.
  • the column passes through the level of the dispersion in the inner cup, that is, the top of the column is above the level of the dispersed liquid in the inner cup, and the height of the column is greater than the height of the dispersion in the inner cup.
  • the dispersion in the inner cup covers the cylinder, that is, the cylinder is completely located in the dispersion of the inner cup, and the height of the cylinder is smaller than the height of the dispersion in the inner cup.
  • the size of the graphene cast in the step 103 is determined by setting the concentration of the graphene oxide dispersion in the step 101, the volume of the graphene oxide dispersion in the step 101, or the hydrothermal reactor in the step 102. The volume is controlled.
  • the graphene oxide dispersion is placed in a hydrothermal reaction vessel, and the reduced graphene is obtained by high temperature and high pressure.
  • the properties of the hydrophobic agglomeration after the reduction of graphene, coupled with the internal high pressure generated by the high temperature enable the forming and casting of the graphene castings with excellent electromechanical properties, and the compressive strength of these castings Can reach 205 ⁇ 10MPa.
  • the mechanical properties of the cast body will be doubled up to a maximum of 401 MPa.
  • the casting method of the present invention utilizes hydrothermal reduction of graphite oxide to achieve simple and efficient casting of graphene.
  • the casting method can overcome the shortcomings of the traditional isostatic pressing technology, and has the advantages of simple equipment, short cycle, low pollution, no need to consider the friction between the solid and the mold, and no need to remove the mold. This simple technique not only allows the casting of different shapes to be obtained, but also the mechanical properties of the resulting castings are very good.
  • a method for casting a graphene cast body comprising the steps of:
  • step 101 The hydrothermal reaction vessel in step 101 is heated to 180 ° C for 15 h, and the mixed solution is formed into a wet graphene gel;
  • the wet graphene gel was taken out from the hydrothermal reaction vessel of the step 102, and dried in an environment of 32 ° C to obtain a graphene cast.
  • the graphene cast body obtained by the casting method of Example 1 was a solid cylindrical shape. Using a vernier caliper, the graphene cast body has a height of 3 mm and a bottom surface diameter of 2. 8 mm.
  • the graphene cast body was subjected to a compressive strength test.
  • the compressive strength test process is as follows: First, the graphene casting body is flattened at both ends, and then the graphene cast body is placed on the sample stage of the electronic universal machine, and then the test board located at the upper part of the sample stage is at a rate of 1 mm/min. The graphene cast body is pressed down, and the compressive strength can be obtained by a computer.
  • the electronic universal machine used in the compressive strength test was produced by Chengchun Experimental Research Institute, model number CSS_2202.
  • the test results are shown in Figure 1.
  • the abscissa in Fig. 1 indicates the pfH of the mixed solution formed by adding ammonia water to the graphene oxide dispersion in step 101, and the ordinate indicates the compressive strength of the finally obtained graphene cast body in step 103, in units of MPa.
  • the pH of the mixed solution is 10.1
  • the compressive strength of the graphene cast body is up to 215 MPa.
  • the casting method of the graphene cast body is the same as that of the first embodiment, and the difference is that in step 101, the wall surface of the inner cup of the hydrothermal reaction vessel is engraved in a gear shape.
  • the graphene cast body obtained by the casting method of Example 2 was a graphene gear.
  • the casting method of the graphene cast body was the same as in Example 1, except that the concentration of the graphene oxide dispersion was 7 mg/ml.
  • the graphene cast body obtained by the casting method of Example 3 was a solid cylindrical shape. Using a vernier caliper, the graphene cast body has a height of 3. 5 mm and a bottom surface diameter of 3. 0 mm. Thereby, the size of the graphene cast body can be increased by increasing the concentration of the graphene oxide dispersion liquid while the other step conditions are not changed.
  • Example 4
  • the casting method of the graphene cast body was the same as in Example 1, except that the graphene oxide dispersion was 45 ml.
  • the graphene cast body obtained by the casting method of Example 4 was a solid cylindrical shape. Using a vernier caliper, the graphene cast body has a height of 3. 2 mm and a bottom surface diameter of 3. lmm. Thereby, the size of the graphene cast body can be increased by increasing the volume of the graphene oxide dispersion liquid while the other step conditions are not changed.
  • the casting method of the graphene cast body was the same as in Example 1, except that the inner cup volume of the hydrothermal reaction vessel was 100 ml.
  • the graphene cast body obtained by the casting method of Example 5 was a solid cylindrical shape. Using a vernier caliper, the graphene cast body has a height of 2. 8 mm and a bottom surface diameter of 3 mm. Thus, the size of the graphene cast body can be changed by changing the inner cup volume of the hydrothermal reaction vessel without changing the conditions of the other steps. In this embodiment, the aspect ratio of the graphene cast body was changed as compared with the first embodiment.
  • the casting method of the graphene cast body was the same as in Example 1, except that ammonia water was not added in the step 101, and the pH of the mixed solution was 5.9.
  • the casting method of the graphene cast body is the same as that of the embodiment 1, except that the ammonia water is added in the step 101, and the pH values of the mixed solution are 7.7, 8. 5, 9.4, 10.7, 11.6, respectively.
  • Example 12 The graphene cast body prepared in Example 7-9 was subjected to compressive strength test, and the process of compressive strength test was the same as that in Example 1. The test results are shown in Fig. 1. At a pH of 7.7, the maximum compressive strength of the graphene cast is 136 MPa. At a pH of 8.5, the maximum compressive strength of the graphene cast is 159 MPao pH 9.4, and the maximum compressive strength of the graphene cast is 176 MPa. At a pH of 10.7, the maximum compressive strength of the graphene cast body is 90 MPa. At a pH of 11.6, the maximum compressive strength of the graphene cast body is 67 MPa. Example 12
  • the casting method of the graphene cast body is the same as that of the first embodiment.
  • the difference is that the high-temperature annealing treatment step is added, and the graphene cast body finally obtained in 103 is placed in a tube furnace filled with nitrogen at 12 ° C.
  • the rate of /min is raised to 900 V and maintained for 60 min, then the heating is stopped, the tube furnace is cooled, and when the temperature of the tube furnace is lower than 350 ° C, the nitrogen gas is stopped, and the tube furnace is cooled to room temperature.
  • the graphene cast body prepared in this example was subjected to compressive strength test, and the process of compressive strength test was the same as that in Example 1.
  • the test results are shown in Fig. 2.
  • the abscissa indicates the pfH of the mixed solution formed by adding ammonia water to the graphene oxide dispersion in step 101
  • the ordinate indicates the compressive strength of the graphene cast body after the high-temperature annealing treatment, in units of MPa.
  • the maximum compressive strength of the graphene cast body reached 401 MPa. Compared with Example 1, the maximum compressive strength of the graphene cast body of this example was nearly doubled.
  • the graphene cast bodies obtained in Examples 6 to 11 were respectively subjected to a high temperature annealing treatment step, and the high temperature annealing treatment step was the same as in Example 12.
  • the graphene casts prepared in Examples 13-18 were subjected to compressive strength test, and the process of compressive strength test was the same as in Example 1, and the test results are shown in Fig. 2.
  • the maximum compressive strength of the graphene cast body is 153 MPa.
  • the maximum compressive strength of the graphene cast body is 160 MPa.
  • the pH is 8.5
  • the maximum compressive strength of the graphene cast body is 225 MPa.
  • the pH 9.4
  • the maximum compressive strength of the graphene cast body is 261 MPa.
  • the maximum compressive strength of the graphene cast body is 39 MPa.
  • the maximum compressive strength of the graphene cast body was 17 MPa.
  • the maximum compressive strength of the olefin cast is much greater than the maximum compressive strength of the graphene cast without high temperature annealing.
  • the pH is 10.1
  • the maximum compressive strength of the graphene cast after high temperature annealing is 215 MPa
  • the maximum compressive strength of the graphene cast without high temperature annealing is 401 MPa.

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Abstract

本发明公开了一种石墨烯铸体的铸造方法，其特征在于，该铸造方法包括以下步骤：101.将浓度为0.5mg/ml-7mg/ml的氧化石墨烯分散液，倒入水热反应釜内杯中，并加入氨水或氢氧化钠，形成pH值范围为5.5-11.6的混合溶液；102.将步骤101中的水热反应釜升温至150℃-350℃，并持续3h-48h，混合溶液形成湿石墨烯凝胶；103.从步骤102的水热反应釜中取出湿石墨烯凝胶，在20℃-70℃的环境下干燥，得到石墨烯铸体。该铸造方法过程简单，可以调控石墨烯铸体的力学性能，并且使得石墨烯铸体具有良好的力学性能。

Description

一种石墨烯铸体的铸造方法 技术领域 本发明涉及一种石墨烯铸体的铸造方法。 背景技术
等静压成型技术在金属和陶瓷材料的研究和发展中起到了至关重要的作用 (Bocanegra-bernal, M. H. Journal of Material Science 2004, 39, 6399； Biasini, V. , Parasporo, M.， Bel losi, A. Thin Sol id Fi lms 1997， 297, 207)。 该技术可以对 材料粉末从各个方向进行挤压， 从而得到高密度高强度的实体 (Kim， H. S. Journal of Material Processing Technology 2002, 123, 319)。 等静压石墨就是该技术的直接应 用， 该种石墨具有各向同性的特点。传统的等静压石墨的铸造方法通常包括粉料的制备、 等静压成型固实、煅烧和石墨化。该铸造方法步骤多、周期长、且对设备的要求苛刻 (Ragan, A. Journal of Materials Science 1983, 18, 3161)。 另外， 在成型过程中， 还必需考 虑实体与弹性模具的摩擦作用， 最后还需要去除模具（Lee， S. C.， Kim, K. Τ. Materials Science and Engineering A 2008, 498, 359)。
自从被发现以来， 石墨烯引起了科学界强烈的研究兴趣 (Novoselov, K. S. et al. Science 2004, 306， 666)。 由于石墨烯具有单原子层厚度， 因此被广泛的用作为各种复 杂结构的基本单元（Compton, 0. C.， Nguyen, S. T. Smal l 2010, 6， 711 ; Xu, Y. X. , Wu, Q. , S, Υ. Q. , Bai, Η. , Shi, G. Q. ACS Nano 2010, 4， 7358 ; Chen, Z. P. et al. Nature Mater. 2011, 10, 424)。 基于石墨烯具有大的比表面积， 使得石墨烯很容易通 过自组装的方式， 得到单层或多层的薄膜及三维的结构。 但是， 直到现在还没有关于石 墨烯铸体铸造方面的相关报道。
发明内容
技术问题： 本发明所要解决的技术问题是： 提供一种石墨烯铸体的铸造方法， 该铸 造方法过程简单， 可以调控石墨烯铸体的力学性能， 并且使得石墨烯铸体具有良好的力 学性能。
技术方案： 为解决上述技术问题， 本发明采用的技术方案是：
一种石墨烯铸体的铸造方法， 该铸造方法包括以下步骤：
101.将浓度为 0. 5mg/ml-7mg/ml 的氧化石墨烯分散液， 倒入水热反应釜内杯中， 并 加入氨水或氢氧化钠， 形成 pH值范围为 5. 5-11. 6的混合溶液；
102.将步骤 101中的水热反应釜升温至 150°C-350°C， 并持续 3h_48h， 混合溶液形 成湿石墨烯凝胶；
103.从步骤 102的水热反应釜中取出湿石墨烯凝胶，在 20°C-70°C的环境下干燥，得 到石墨烯铸体。
所述的石墨烯铸体的铸造方法， 还包括步骤 104高温退火处理， 所述的高温退火处 理是将步骤 103中的石墨烯铸体， 置于充有氮气的管式炉中， 以 12°C/min的速率升温至 900°C， 并维持 60min， 然后停止加热， 管式炉降温， 待管式炉的温度低于 350°C时， 停 止通氮气， 管式炉降温至室温。
所述的步骤 103中的石墨烯铸体的形状由步骤 101中的水热反应釜内杯形状决定。 所述的步骤 103中的石墨烯铸体的形状由步骤 101中的水热反应釜放置的位置决定。 所述的步骤 103中的石墨烯铸体的大小， 通过设定步骤 101中的氧化石墨烯分散液 的浓度， 步骤 101中的氧化石墨烯分散液的体积， 或者步骤 102中的水热反应釜的容积， 进行控制。
有益效果： 与现有技术相比， 本发明具有以下有益效果：
1.铸造方法简单。 本发明提供的铸造方法仅包括三个步骤， 只需通过简单的水热还 原就可将氧化石墨烯还原成团聚的石墨烯铸体。 传统的等静压石墨一般需要七步才能完 成， 过程繁杂。 与现有技术相比， 本铸造方法过程简单。 同时， 传统的制作等静压石墨 的过程中， 需要使用昂贵的设备， 价格上百万。 而本发明的铸造方法， 仅需要使用水热 反应釜， 设备简单， 价格低廉。
2.石墨烯铸体具有很好的力学性能。 本发明的铸造方法， 通过增加高温退火处理步 骤， 可以大大提高石墨烯铸体的抗压强度。 与没有经过高温退火处理的石墨烯铸体相比， 经过高温退火处理的石墨烯铸体抗压强度可提高 1倍。 与传统石墨相比， 经过高温退火 处理的石墨烯铸体的抗压强度可提高 5倍。
3.可以方便的控制石墨烯铸体的力学性能。 本发明的铸造方法，
通过控制步骤 1的混合溶液的不同 pfH ， 可以得到石墨烯铸体不同的抗压强度。 混 合溶液 pH值的调整， 可以通过调整步骤 1中的氨水或氢氧化钠的浓度或加入量， 也可以 通过调整氧化石墨烯分散液的浓度或加入量。 混合溶液 pH值的调整便捷简单， 所以， 本 铸造方法可以方便的控制石墨烯铸体的力学性能。 4.控制石墨烯铸体的大小和形状非常便利。 本发明的石墨烯铸体的铸造方法中， 石 墨烯铸体的大小可以通过改变氧化石墨烯分散液的浓度、 氧化石墨烯分散液体积和反应 釜体积的大小加以控制。增加氧化石墨烯分散液的浓度， 所得石墨烯铸体的尺寸会变大; 增大氧化石墨烯分散液的体积， 所得石墨烯铸体尺寸会变大； 增大水热反应釜的容积， 所得石墨烯铸体尺寸会变大。 通过设置水热反应釜内杯的形状， 或者水热反应釜放置的 位置， 来设置石墨烯铸体的形状。 该方法设置石墨烯铸体的形状， 简单且定形稳定。 附图说明
图 1 为没有高温退火步骤时， 混合溶液不同的 pfH ， 对应的石墨烯铸体的抗压 强度柱形图。
图 2为增加高温退火步骤时， 混合溶液不同的 pH值， 对应的石墨烯铸体的抗压 强度柱形图。
在图 1和图 2中，每个柱体代表抗压强度的平均值，而位于每个柱体上部的工字 的上端代表抗压强度的最大值， 工字的下端代表抗压强度的最小值。
具体实施方式
下面结合附图， 具体介绍本发明的技术方案。
本发明的一种石墨烯铸体的铸造方法， 该铸造方法包括以下步骤：
101.将浓度为 0. 5mg/ml-7mg/ml 的氧化石墨烯分散液， 倒入水热反应釜内杯中， 并 加入氨水或氢氧化钠， 形成 pH值范围为 5. 5-11. 6的混合溶液。
在该步骤中，混合溶液的 pH值范围优选为 8. 5— 10. 1， 即混合溶液为弱碱性溶液时， 具有较强的力学性能。
102.将步骤 101中的水热反应釜升温至 150°C-350°C， 并持续 3h_48h， 混合溶液形 成湿石墨烯凝胶。
在该步骤中， 所述的水热反应釜升温优选在 150-280 °C之间。
103.从步骤 102的水热反应釜中取出湿石墨烯凝胶，在 20°C-70°C的环境下干燥，得 到石墨烯铸体。
作为优选方案： 所述的石墨烯铸体的铸造方法， 还包括步骤 104高温退火处理， 所 述的高温退火处理是将步骤 103中的石墨烯铸体， 即经过干燥处理的石墨烯铸体， 置于 充有氮气的管式炉中， 以 12°C/min的速率升温至 900°C， 并维持 60min， 然后停止加热， 管式炉降温， 待管式炉的温度低于 350°C时， 停止通氮气， 管式炉降温至室温。
当管式炉温度低于 35CTC时， 停止通氮气， 主要是为了节省氮气。 管式炉的温度从 900 °〇降低到室温的过程中， 没有施加人为干预， 管式炉自身在大气环境中降温。 经过高温 退火处理的石墨烯铸体具有良好的力学性能。
步骤 103中的石墨烯铸体的形状可以由步骤 101中的水热反应釜的位置或者内部构 造决定。
所述的步骤 103中的石墨烯铸体的形状由步骤 101中的水热反应釜内杯形状决定。 当步骤 101中的水热反应釜的内杯为球形时， 步骤 103中的石墨烯铸体为石墨烯球体； 当步骤 101中的水热反应釜的内杯为三棱柱形时， 步骤 103中的石墨烯铸体为石墨烯三 棱柱； 当步骤 101中的水热反应釜的内杯为四棱柱形时， 步骤 103中的石墨烯铸体为石 墨烯四棱柱； 当步骤 101中的水热反应釜的内杯的壁面刻成齿轮状时， 步骤 103中的石 墨烯铸体为石墨烯齿轮； 当步骤 101 中的水热反应釜的内杯的壁面刻成螺旋状时， 步骤 103中的石墨烯铸体为石墨烯螺旋体。
所述的步骤 103中的石墨烯铸体的形状由步骤 101中的水热反应釜放置的位置决定。 当步骤 101中的水热反应釜为竖立放置时， 步骤 103中的石墨烯铸体为圆柱体； 当步骤 101 中的水热反应釜为水平放置时， 步骤 103 中的石墨烯铸体为半圆柱体； 当步骤 101 中的水热反应釜为倾斜放置时， 步骤 103中的石墨烯铸体为剖面为梯形的圆柱体。
铸造石墨烯空心圆柱体和石墨烯坩埚时： 步骤 101 中的水热反应釜为竖立放置， 水 热反应釜的内杯中心设置一个柱体； 当该柱体穿过内杯中的分散液液面时， 步骤 103中 的石墨烯铸体为空心圆柱体； 当内杯中的分散液包覆该柱体时， 步骤 103中的石墨烯铸 体为石墨烯坩埚。 柱体穿过内杯中的分散液液面， 就是说， 柱体的顶部位于内杯中的分 散液液面上方， 柱体的高度大于内杯中分散液的高度。 内杯中的分散液包覆柱体， 就是 说， 柱体完全位于内杯的分散液中， 柱体的高度小于内杯中分散液的高度。
所述的步骤 103中的石墨烯铸体的大小， 通过设定步骤 101中的氧化石墨烯分散液 的浓度， 步骤 101中的氧化石墨烯分散液的体积， 或者步骤 102中的水热反应釜的容积， 进行控制。
本发明将氧化石墨烯分散液置于水热反应釜中， 利用高温高压得到了还原后的石墨 烯。 在反应的过程中， 利用石墨烯还原后憎水团聚的性质， 再加上高温自产生的内部高 压，实现了力电性能优良的石墨烯铸体的成型铸造，且这些铸体的抗压强度可以达到 205 ± 10MPa。 另外， 经过简单的高温退火处理， 将会使得铸体的力学性能提升一倍， 最大可 达 401MPa。 特别是氨水的加入， 使得石墨烯铸体的力电性能都有了很大程度的提高， 从 而对石墨烯的宏观应用开辟了一条新路。 本发明的铸造方法利用氧化石墨的水热还原， 可以实现石墨烯的简单高效铸造。 该铸造方法可以克服传统等静压技术的缺点， 使其具 有设备简单、 周期短、 污染小、 不用考虑实体与模具间的摩擦作用、 不需去除模具等优 势。 该简单的技术不仅可以得到不同形状的铸体， 而且所得铸体的力学性能非常好。 实施例 1
一种石墨烯铸体的铸造方法， 该铸造方法包括以下步骤：
101.将浓度为 4mg/ml的氧化石墨烯分散液 33ml，倒入水热反应釜内杯中，该内杯的 形状为圆柱体， 内杯容积为 50ml， 且该水热反应釜竖立放置， 然后加入氨水， 形成 pH 值为 10. 1的混合溶液；
102.将步骤 101中的水热反应釜升温至 180°C，并持续 15h，混合溶液形成湿石墨烯 凝胶；
103.从步骤 102的水热反应釜中取出湿石墨烯凝胶，在 32°C的环境下干燥，得到石 墨烯铸体。
通过实施例 1的铸造方法制得的石墨烯铸体， 为实心圆柱形。 使用游标卡尺测量， 该石墨烯铸体高度 3mm， 底面直径为 2. 8mm。 对该石墨烯铸体进行抗压强度测试。 抗压强 度测试的过程是： 首先将石墨烯铸体两端磨平， 然后将石墨烯铸体置于电子万能机的样 品台上， 接着以 lmm/min的速率将位于样品台上部的测试板向下压石墨烯铸体， 通过电 脑可得到抗压强度。 该抗压强度测试中使用的电子万能机为成春实验研究所生产， 型号 为 CSS_2202。 测试结果如图 1所示。 图 1中横坐标表示步骤 101中， 在氧化石墨烯分散 液中加入氨水后形成的混合溶液的 pfH ,纵坐标表示步骤 103最终的得到的石墨烯铸体 的抗压强度， 单位 MPa。 本实施例中， 混合溶液的 pH为 10. 1， 石墨烯铸体的抗压强度最 大达到了 215MPa。 实施例 2
石墨烯铸体的铸造方法与实施例 1相同， 不同的地方是步骤 101中， 水热反应釜的 内杯的壁面刻成齿轮状。 通过实施例 2的铸造方法制得的石墨烯铸体， 为石墨烯齿轮。 实施例 3
石墨烯铸体的铸造方法与实施例 1相同， 不同的地方是氧化石墨烯分散液的浓度为 7mg/ml。
通过实施例 3的铸造方法制得的石墨烯铸体， 为实心圆柱形。 使用游标卡尺测量， 该石墨烯铸体高度为 3. 5mm， 底面直径为 3. 0mm。 由此， 在其他步骤条件不变的情况下， 通过增加氧化石墨烯分散液的浓度， 可以增加石墨烯铸体的尺寸。 实施例 4
石墨烯铸体的铸造方法与实施例 1相同， 不同的地方是氧化石墨烯分散液为 45ml。 通过实施例 4的铸造方法制得的石墨烯铸体， 为实心圆柱形。 使用游标卡尺测量， 该石墨烯铸体高度为 3. 2mm, 底面直径为 3. lmm。 由此， 在其他步骤条件不变的情况下， 通过增加氧化石墨烯分散液的体积， 可以增加石墨烯铸体的尺寸。 实施例 5
石墨烯铸体的铸造方法与实施例 1 相同， 不同的地方是水热反应釜的内杯容积为 100ml。
通过实施例 5的铸造方法制得的石墨烯铸体， 为实心圆柱形。 使用游标卡尺测量， 该石墨烯铸体高度为 2. 8mm, 底面直径为 3mm。 由此， 在其他步骤条件不变的情况下， 通 过改变水热反应釜的内杯容积， 可以改变石墨烯铸体的尺寸。本实施例与实施例 1相比， 石墨烯铸体的长径比发生了变化。 实施例 6
石墨烯铸体的铸造方法与实施例 1相同， 不同的地方是步骤 101中没有加入氨水， 混合溶液的 pH值为 5. 5。
对本实施例制得的石墨烯铸体进行抗压强度测试， 抗压强度测试的过程同实施例 1， 测试结果如图 1所示， 最大抗压强度可达 124MPa。 实施例 7— 11
石墨烯铸体的铸造方法与实施例 1相同， 不同的地方是步骤 101中加入氨水， 混合 溶液的 pH值分别为 7. 7、 8. 5、 9. 4、 10. 7、 11. 6。
对实施例 7— 9制得的石墨烯铸体进行抗压强度测试，抗压强度测试的过程同实施例 1， 测试结果如图 1所示。 pH值为 7. 7时， 石墨烯铸体的最大抗压强度为 136 MPa。 pH 值为 8. 5时， 石墨烯铸体的最大抗压强度为 159 MPao pH值为 9. 4时， 石墨烯铸体的最 大抗压强度为 176MPa。 pH值为 10. 7时， 石墨烯铸体的最大抗压强度为 90MPa。 pH值为 11. 6时， 石墨烯铸体的最大抗压强度为 67MPa。 实施例 12
石墨烯铸体的铸造方法与实施例 1相同， 不同的地方是增加了高温退火处理步骤， 将 103最终制得的石墨烯铸体，置于充有氮气的管式炉中，以 12 °C /min的速率升温至 900 V， 并维持 60min， 然后停止加热， 管式炉降温， 待管式炉的温度低于 350°C时， 停止通 氮气， 管式炉降温至室温。
对本实施例制得的石墨烯铸体进行抗压强度测试， 抗压强度测试的过程同实施例 1， 测试结果如图 2所示。 图 2中横坐标表示步骤 101中， 在氧化石墨烯分散液中加入氨水 后形成的混合溶液的 pfH ， 纵坐标表示经过高温退火处理后的石墨烯铸体的抗压强度， 单位 MPa。 本实施例中， 石墨烯铸体的最大抗压强度达到了 401MPa。 与实施例 1相比， 本实施例石墨烯铸体的最大抗压强度提高了近一倍。 实施例 13— 18
将实施例 6— 11制得的石墨烯铸体分别进行高温退火处理步骤， 高温退火处理步骤 步骤与实施例 12相同。
对实施例 13— 18制得的石墨烯铸体进行抗压强度测试，抗压强度测试的过程同实施 例 1， 测试结果如图 2所示。 11值为5. 5时， 石墨烯铸体的最大抗压强度为 153MPa。 pH 值为 7. 7时， 石墨烯铸体的最大抗压强度为 160MPa。 pH值为 8. 5时， 石墨烯铸体的最大 抗压强度为 225MPa。 pH值为 9. 4时， 石墨烯铸体的最大抗压强度为 261 MPa。 pH值为 10. 7时， 石墨烯铸体的最大抗压强度为 39MPa。 pfH 11. 6时， 石墨烯铸体的最大抗压强 度为 17MPa。 由此， 对于 pH值范围为 8. 5— 10. 1的混合溶液， 经过高温退火处理的石墨 烯铸体的最大抗压强度都要远远大于没有经过高温退火处理的石墨烯铸体的最大抗压强 度。 例如， pH值为 10. 1时， 经过高温退火处理的石墨烯铸体的最大抗压强度为 215MPa， 而没有高温退火处理的石墨烯铸体的最大抗压强度为 401MPa。

Claims

1.一种石墨烯铸体的铸造方法， 其特征在于， 该铸造方法包括以下步骤：
101.将浓度为 0. 5mg/ml-7mg/ml 的氧化石墨烯分散液， 倒入水热反应釜内杯中， 并 加入氨水或氢氧化钠， 形成 pH值范围为 5. 5-11. 6的混合溶液；
102.将步骤 101 中的水热反应釜升温至 150°C-350°C， 并持续 3h_48h， 混合溶液形 成湿石墨烯凝胶；
103.从步骤 102 的水热反应釜中取出湿石墨烯凝胶， 在 20°C-70°C的环境下干燥， 得到石墨烯铸体。
2.根据权利要求 1 所述的石墨烯铸体的铸造方法， 其特征在于， 所述的步骤 101 中， 混合溶液的 pH值范围为 8. 5—10. 1。
3.根据权利要求 1所述的石墨烯铸体的铸造方法， 其特征在于， 还包括步骤 104高 温退火处理， 所述的高温退火处理是将步骤 103 中的石墨烯铸体， 置于充有氮气的管式 炉中， 以 12°C/min 的速率升温至 900°C， 并维持 60min， 然后停止加热， 管式炉降温， 待管式炉的温度低于 350°C时， 停止通氮气， 管式炉降温至室温。
4.根据权利要求 1所述的石墨烯铸体的铸造方法， 其特征在于，
所述的步骤 103中的石墨烯铸体的形状由步骤 101中的水热反应釜内杯形状决定。
5.根据权利要求 4所述的石墨烯铸体的铸造方法， 其特征在于， 当步骤 101 中的水 热反应釜的内杯为球形时， 步骤 103 中的石墨烯铸体为石墨烯球体； 当步骤 101 中的水 热反应釜的内杯为三棱柱形时， 步骤 103 中的石墨烯铸体为石墨烯三棱柱； 当步骤 101 中的水热反应釜的内杯为四棱柱形时， 步骤 103中的石墨烯铸体为石墨烯四棱柱； 当步骤 101 中的水热反应釜的内杯的壁面刻成齿轮状时， 步骤 103 中的石墨烯铸体为石 墨烯齿轮； 当步骤 101 中的水热反应釜的内杯的壁面刻成螺旋状时， 步骤 103 中的石墨 烯铸体为石墨烯螺旋体。
6.根据权利要求 1所述的石墨烯铸体的铸造方法， 其特征在于，
所述的步骤 103中的石墨烯铸体的形状由步骤 101中的水热反应釜放置的位置决定。
7.根据权利要求 6所述的石墨烯铸体的铸造方法， 其特征在于，
当步骤 101 中的水热反应釜为竖立放置时， 步骤 103 中的石墨烯铸体为圆柱体； 当步骤 101中的水热反应釜为水平放置时， 步骤 103中的石墨烯铸体为半圆柱体； 当步骤 101中 的水热反应釜为倾斜放置时， 步骤 103中的石墨烯铸体为剖面为梯形的圆柱体。
8.根据权利要求 1所述的石墨烯铸体的铸造方法， 其特征在于，
步骤 101 中的水热反应釜为竖立放置， 水热反应釜的内杯中心设置一个柱体； 当该柱体 穿过内杯中的分散液液面时， 步骤 103 中的石墨烯铸体为空心圆柱体； 当内杯中的分散 液包覆该柱体时， 步骤 103中的石墨烯铸体为石墨烯坩埚。
9.根据权利要求 1 所述的石墨烯铸体的铸造方法， 其特征在于， 所述的步骤 103 中 的石墨烯铸体的大小， 通过设定步骤 101 中的氧化石墨烯分散液的浓度， 步骤 101 中的 氧化石墨烯分散液的体积， 或者步骤 102中的水热反应釜的容积， 进行控制。
10.根据权利要求 1 所述的石墨烯铸体的铸造方法， 其特征在于， 所述的步骤 102 中， 所述的水热反应釜升温至 150-28CTC之间。
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