CN110776338A - Microcrystalline graphite antioxidant and preparation method and application thereof - Google Patents

Microcrystalline graphite antioxidant and preparation method and application thereof Download PDF

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Publication number
CN110776338A
CN110776338A CN201911067564.6A CN201911067564A CN110776338A CN 110776338 A CN110776338 A CN 110776338A CN 201911067564 A CN201911067564 A CN 201911067564A CN 110776338 A CN110776338 A CN 110776338A
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China
Prior art keywords
antioxidant
graphite
graphite material
phosphoric acid
hydrogen phosphate
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CN201911067564.6A
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Chinese (zh)
Inventor
何成林
刘金平
杨程
王新华
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Hunan Changyu Science And Technology Development Co Ltd
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Hunan Changyu Science And Technology Development Co Ltd
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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
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
    • C04B41/81—Coating or impregnation
    • C04B41/85—Coating or impregnation with inorganic materials
    • 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
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
    • 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
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
    • C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
    • C04B41/5016—Acids

Abstract

The invention discloses a microcrystalline graphite antioxidant and a preparation method and application thereof, wherein the antioxidant is a mixed solution of phosphoric acid and disodium hydrogen phosphate, and the volume mol ratio of the phosphoric acid to the disodium hydrogen phosphate before mixing is 100: (0.01-0.02) mL/mol. The antioxidant is used in microcrystalline graphite-based isotropic graphite materials. The antioxidant is infiltrated into the graphite material, and the phosphoric acid and the disodium hydrogen phosphate are dehydrated by heating under the high-temperature condition to generate a series of changes to finally generate P 4O 10，P 4O 10The phosphorus-oxygen crosslinked glass structure is a phosphorus-oxygen crosslinked network structure, and is attached to the surface of an inner hole of a graphite material to form an inner hole coating, so that oxidizing gas can be well prevented from permeating into the graphite material, and the oxidation resistance of the graphite material is effectively improved.

Description

Microcrystalline graphite antioxidant and preparation method and application thereof
Technical Field
The invention relates to the technical field of graphite materials, and particularly relates to a microcrystalline graphite antioxidant and a preparation method and application thereof.
Background
The graphite material has good high-temperature performance. However, the problem of oxidation is also very prominent, and the oxidation is easy to occur especially under the condition of high temperature (the graphite material begins to be oxidized at about 400 ℃ in the air). At present, the oxidation resistance research of graphite materials at home and abroad can be basically divided into three types: (1) an impregnation method; (2) coating method; (3) and (4) self-healing. In view of cost, the impregnation method is the best method, and the impregnation method is used for filling pores and covering the surface of the graphite material to form an anti-oxidation barrier layer to slow down the oxidation speed and achieve the purpose of reducing the oxidation consumption. The existing impregnation method antioxidant still has the problem of weak oxidation resistance, and the development of graphite material antioxidant with better oxidation resistance is urgently needed.
Disclosure of Invention
The invention mainly aims to provide a microcrystalline graphite antioxidant, and a preparation method and application thereof.
In order to achieve the above object, according to one aspect of the present invention, there is provided a microcrystalline graphite antioxidant which is a mixed solution of phosphoric acid and disodium hydrogen phosphate, the volume molar ratio of phosphoric acid to disodium hydrogen phosphate before mixing being 100: (0.01-0.02) mL/mol.
Further, the volume mol ratio of the phosphoric acid to the disodium hydrogen phosphate before mixing is 100: 0.02 mL/mol. It was found that when the amount of disodium hydrogenphosphate exceeds 0.02mol (relative to 100mL of phosphoric acid), some of the disodium hydrogenphosphate does not form an antioxidant substance; therefore, when the amount of disodium hydrogen phosphate exceeds 0.02mol, not only the oxidation resistance of the graphite material cannot be further improved, but also the production cost is increased; combining oxidation resistance and cost factors, the volume mol ratio of the phosphoric acid to the disodium hydrogen phosphate before mixing is 100: 0.02mL/mol is the best solution.
According to another aspect of the invention, the preparation method of the microcrystalline graphite antioxidant is provided, and disodium hydrogen phosphate dodecahydrate is added into a phosphoric acid solution according to a ratio and is uniformly mixed to obtain the antioxidant.
Furthermore, the phosphoric acid solution is analytically pure, the concentration of the phosphoric acid solution is more than or equal to 85 percent, and the density of the phosphoric acid solution at 20 ℃ is 1.69 g/mL; disodium hydrogen phosphate dodecahydrate is analytically pure, and the purity of the disodium hydrogen phosphate dodecahydrate is more than or equal to 99 percent.
According to a further aspect of the present invention there is provided the use of a microcrystalline graphite antioxidant as described above in a microcrystalline graphite based isotropic graphite material. The antioxidant of the invention can also be applied to other graphite materials with fine structures.
Further, processing the microcrystalline graphite-based isotropic graphite material into a small sample; then, the graphite material is soaked and washed in absolute ethyl alcohol to remove impurity particles on the surface of the graphite material, and the graphite material is taken out and placed in a ventilation position to volatilize the ethyl alcohol on the surface of the graphite material; putting the graphite material into the antioxidant, putting the antioxidant into vacuum-pumping equipment for vacuum-pumping treatment, and continuously performing the vacuum-pumping treatment for a period of time; taking out the graphite material, drying and curing.
Compared with the prior art, the invention has the beneficial effects that:
the invention firstly mixes phosphoric acid and disodium hydrogen phosphate according to a specific proportion to prepare the microcrystalline graphite antioxidant, the antioxidant is soaked and infiltrated into the graphite material, the phosphoric acid and the disodium hydrogen phosphate are heated and dehydrated under the high temperature condition to generate a series of changes, and finally P is generated 4O 10，P 4O 10The phosphorus-oxygen crosslinked glass structure is a phosphorus-oxygen crosslinked network structure, and is attached to the surface of an inner hole of a graphite material to form an inner hole coating, so that oxidizing gas is well prevented from permeating into the graphite material, and the oxidation resistance of the graphite material is effectively improved.
Drawings
FIG. 1 is a graph showing the measurement data of the oxidation weight loss ratios of the samples of example 1 of the present invention and comparative examples 1 to 3.
FIG. 2 is the measurement data of the oxidation weight loss ratios of the samples of examples 1 to 3 of the present invention.
Detailed Description
In order to facilitate an understanding of the present invention, the present invention will be described more fully and in detail with reference to the preferred embodiments, but the scope of the present invention is not limited to the specific embodiments described below.
Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
The chemical reagents used in the invention: h 3PO 4Solution (AR, density 1.69g/mL (20 ℃), concentration > 85%, calculated according to 85% in the invention); na (Na) 2HPO 4·12H 2O (AR, purity is more than or equal to 99%); AlPO 4(CP, purity 98%); absolute ethyl alcohol (AR, density 0.790g/mL (20 ℃), concentration greater than or equal to 99.7%); distilled water (self-made).
Example 1:
(1) preparation of antioxidant:
with H 3PO 4The solution is a solvent and Na is used 2HPO 4·12H 2And O is a solute, and the O is mixed to prepare a mixed solution of phosphoric acid and disodium hydrogen phosphate, namely the microcrystalline graphite antioxidant. Wherein, H is used 3PO 4The volume of the solution was 100mL, Na used 2HPO 4·12H 2The amount of O was 0.01 mol.
(2) Preparation and impregnation of graphite material samples:
the microcrystalline graphite-based isotropic graphite material was machined into small cylinders of phi 20mm x 20mm, 10 samples per group. Two parallel samples are taken at each temperature point, the samples are clamped by long tweezers and are soaked and washed in prepared absolute ethyl alcohol, impurity particles on the surfaces of the samples are removed, and then the samples are taken out and placed in a ventilated place for 30min, so that the ethyl alcohol on the surfaces of the samples is volatilized;
respectively putting the processed samples into a plurality of beakers containing the antioxidant, putting the beakers into a vacuumizing device, and vacuumizing until the pressure is-0.1 MPa and the duration is about 2 hours, wherein the antioxidant solution is continuously immersed into the samples until the antioxidant solution is soaked; taking out the sample and then putting the sample into an oven for drying and curing; heating the oven: drying at room temperature-100 deg.C for 20min, and drying at 100 deg.C for 2 hr.
(3) Measurement of oxidation weight loss ratio of impregnated sample:
in this example, oxidation resistance of a sample was analyzed by selecting oxidation weight loss ratios at five temperature points of 500 ℃, 600 ℃, 700 ℃, 800 ℃ and 900 ℃.
The experimental steps are as follows: 1) preparing a plurality of boats, cleaning the boats with distilled water, putting the boats into an oven, drying the boats for 30min at 100 ℃, taking the boats out, cooling the boats for 10min, and measuring the dry weight of the boats; 2) stably placing the microcrystalline graphite-based isotropic graphite material sample subjected to antioxidant impregnation treatment into a ark, and weighing the total weight of the antioxidant impregnated microcrystalline graphite-based isotropic graphite material sample and the ark; 3) raising the temperature of the muffle furnace, putting the ark and the sample together when the temperature is constant at 500 ℃, half opening the furnace door, burning for 1h, taking out, cooling in the air for 10min, and weighing; repeating the steps, respectively heating and keeping the temperature to 600 ℃, 700 ℃, 800 ℃ and 900 ℃ to carry out the oxidation weight loss rate determination experiment.
The calculation formula of the oxidation weight loss rate is as follows:
ω oxidation by oxygen＝(m A-m B)/(m A-m)×100％
In the above formula: omega Oxidation by oxygenThe oxidation weight loss rate is expressed in unit; m is dry weight of the square boat and is in g; m is AThe weight of the burnt foreboat and the sample is g; m is BThe weight of the ark and sample after firing is given in g.
The results of measuring the oxidation weight loss ratio of the impregnated sample in this example are shown in fig. 1 and 2.
Comparative example 1:
by means of H 3PO 4The solution is used as antioxidant without adding Na 2HPO 4·12H 2O，H 3PO 4The amount of the solution used was 100 mL.
The preparation and impregnation steps of the graphite material sample and the measurement step of the oxidation weight loss ratio of the impregnated sample were the same as in example 1. The results of measurement of the oxidation weight loss ratio of the impregnated sample are shown in FIG. 1.
Comparative example 2:
with H 3PO 4The solution is used as a solvent and AlPO 4Mixing a mixed solution (H) prepared from phosphoric acid and aluminum dihydrogen phosphate as a solute 3PO 4Solution with AlPO 4Can react to generate aluminum dihydrogen phosphate; the phosphoric acid is excessive according to the dosage of the formula, and the product is a mixed solution of phosphoric acid and aluminum dihydrogen phosphate), namely the microcrystalline graphite antioxidant. Wherein, H is used 3PO 4The volume of the solution was 100mL, and AlPO was used 4The amount of (B) was 0.01 mol.
The preparation and impregnation steps of the graphite material sample and the measurement step of the oxidation weight loss ratio of the impregnated sample were the same as in example 1. The results of measurement of the oxidation weight loss ratio of the impregnated sample are shown in FIG. 1.
Comparative example 3:
this comparative example is a blank test, i.e. no antioxidant is used.
The procedure for measuring the oxidation weight loss ratio of the sample was the same as in example 1. The results of measuring the oxidation weight loss ratio of the sample are shown in FIG. 1.
In FIG. 1, 1 #Is a sample of comparative example 1, 2 #Is a sample of example 1, 3 #Sample No. 4 of comparative example 2 #The sample of comparative example 3 (non-impregnated blank).
As can be seen from FIG. 1, 4 #The oxidation degree of the sample and other samples before 500 ℃ is very small, and is almost 7 percent. But starting from 500 ℃ 4 #The oxidation weight loss rate of the sample is greatly changed, particularly, the oxidation weight loss rate is increased to nearly 42% from less than 10% at the temperature of 500 ℃ to 600 ℃, the change of the oxidation weight loss rate is slowed down and still has an increasing trend at the temperature of 600 ℃ to 800 ℃, and the oxidation weight loss rate is as high as 68.4% at the temperature of 900 ℃. The change trend of the oxidation weight loss rate of other samples impregnated with the antioxidant is the same, the oxidation weight loss rates of the samples are gradually increased between 500 ℃ and 900 ℃, and the oxidation weight loss rates at 900 ℃ are all about 50 percent and are more than 4 percent #The oxidation weight loss rate of the sample is reduced by at least 18.4%. Therein, 2 #The sample has the best oxidation resistance, the oxidation weight loss rate at 900 ℃ is only 46.7 percent, and the oxidation weight loss rate in other temperature ranges is also more than 1 #And 3 #Lower of the sample. Description 2 #The impregnated samples of the formulation had the best oxidation resistance.
Example 2:
with H 3PO 4The solution is a solvent and Na is used 2HPO 4·12H 2And O is a solute, and the O is mixed to prepare a mixed solution of phosphoric acid and disodium hydrogen phosphate, namely the microcrystalline graphite antioxidant. Wherein, H is used 3PO 4The volume of the solution was 100mL, Na used 2HPO 4·12H 2The amount of O was 0.015 mol.
The preparation and impregnation steps of the graphite material sample and the measurement step of the oxidation weight loss ratio of the impregnated sample were the same as in example 1. The results of measurement of the oxidation weight loss ratio of the impregnated sample are shown in FIG. 2.
Example 3:
with H 3PO 4The solution is a solvent and Na is used 2HPO 4·12H 2And O is a solute, and the O is mixed to prepare a mixed solution of phosphoric acid and disodium hydrogen phosphate, namely the microcrystalline graphite antioxidant. Wherein, H is used 3PO 4The volume of the solution was 100mL, Na used 2HPO 4·12H 2The amount of O was 0.02 mol. Due to Na 2HPO 4·12H 2O is in H 3PO 4The problem of dissolution in solution, Na in this example 2HPO 4·12H 2O is in H 3PO 4Maximum solubility in solution.
The preparation and impregnation steps of the graphite material sample and the measurement step of the oxidation weight loss ratio of the impregnated sample were the same as in example 1. The results of measurement of the oxidation weight loss ratio of the impregnated sample are shown in FIG. 2.
H is used in examples 1, 2 and 3 3PO 4The solution is a solvent and Na is used 2HPO 4·12H 2O is solute, and is mixed to prepare a mixed solution of phosphoric acid and disodium hydrogen phosphate as an antioxidant. Only Na in the antioxidant 2HPO 4·12H 2The amount of O varies.
As can be seen from fig. 2, the oxidation weight loss ratios of the second and third groups of samples are not greatly affected by the concentration of the phosphate impregnant within 500-700 ℃, but have a tendency to decrease compared with the first group, and are greatly affected by the concentration within 700-900 ℃, especially around 800 ℃, and the oxidation weight loss ratios of the second and third groups of samples are respectively reduced by 8.5% and 10.2% compared with the oxidation weight loss ratio of the first group, and the decrease is the largest in five temperature points. The third group of samples had an oxidation weight loss of 37% at 900 c, which was lower than that of the other two groups.
In FIG. 2, along with Na in the antioxidant 2HPO 4·12H 2The increase in the amount of O also reduced the oxidative weight loss of the impregnated sample over the temperature range studied. I.e. the antioxidant properties of the impregnated samples follow Na 2HPO 4·12H 2The amount of O increases.
As can be seen from fig. 1 and 2, the microcrystalline graphite-based isotropic graphite material impregnated with the antioxidant of examples 1, 2 and 3 of the present invention has better oxidation resistance than the comparative examples 1, 2, 3 and 4. Wherein 100mL of H was immersed 3PO 4+0.02mol Na 2HPO 4·12H 2The antioxidant effect of the antioxidant O sample was the best. It is 31% lower than that of blank sample at 900 deg.c.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (6)

1. The microcrystalline graphite antioxidant is a mixed solution of phosphoric acid and disodium hydrogen phosphate, and the volume molar ratio of the phosphoric acid to the disodium hydrogen phosphate before mixing is 100: (0.01-0.02) mL/mol.
2. The microcrystalline graphite antioxidant of claim 1, wherein the molar ratio of phosphoric acid to disodium phosphate before mixing is 100: 0.02 mL/mol.
3. The method for preparing the microcrystalline graphite antioxidant as claimed in claim 1 or 2, wherein disodium hydrogen phosphate dodecahydrate is added to the phosphoric acid solution according to the proportion and is uniformly mixed to obtain the antioxidant.
4. The method according to claim 3, wherein the phosphoric acid solution is an analytically pure solution having a concentration of 85% or more and a density of 1.69g/mL at 20 ℃; the disodium hydrogen phosphate dodecahydrate is analytically pure, and the purity of the disodium hydrogen phosphate dodecahydrate is more than or equal to 99%.
5. Use of a microcrystalline graphite antioxidant according to claim 1 or 2 in a microcrystalline graphite based isotropic graphite material.
6. Use according to claim 5, characterized in that microcrystalline graphite-based isotropic graphite material is processed into small samples; then, the graphite material is soaked and washed in absolute ethyl alcohol to remove impurity particles on the surface of the graphite material, and the graphite material is taken out and placed in a ventilation position to volatilize the ethyl alcohol on the surface of the graphite material; putting the graphite material into the antioxidant, putting the antioxidant into vacuum-pumping equipment for vacuum-pumping treatment, and continuously performing the vacuum-pumping treatment for a period of time; taking out the graphite material, drying and curing.
CN201911067564.6A 2019-11-04 2019-11-04 Microcrystalline graphite antioxidant and preparation method and application thereof Pending CN110776338A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115028471A (en) * 2022-06-10 2022-09-09 中南大学 Carbon material product antioxidant inorganic coating and application thereof

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CN104163657A (en) * 2014-07-21 2014-11-26 中国矿业大学(北京) Graphite mould antioxidant impregnation liquid, preparation method and application method thereof
CN109320294A (en) * 2018-09-18 2019-02-12 平顶山东方碳素股份有限公司 A kind of graphite antioxidant and preparation method thereof

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Publication number Priority date Publication date Assignee Title
US4439491A (en) * 1982-11-18 1984-03-27 Great Lakes Carbon Corporation Oxidation retardant for graphite
CN102408252A (en) * 2011-12-06 2012-04-11 上海交通大学 Graphite rotor antioxidant for molten aluminum degassing and preparation method thereof
CN104163657A (en) * 2014-07-21 2014-11-26 中国矿业大学(北京) Graphite mould antioxidant impregnation liquid, preparation method and application method thereof
CN109320294A (en) * 2018-09-18 2019-02-12 平顶山东方碳素股份有限公司 A kind of graphite antioxidant and preparation method thereof

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115028471A (en) * 2022-06-10 2022-09-09 中南大学 Carbon material product antioxidant inorganic coating and application thereof
CN115028471B (en) * 2022-06-10 2023-09-26 中南大学 Antioxidant inorganic coating for carbon material product and application thereof

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Application publication date: 20200211