Graphene coating for zirconium tube and preparation and application thereof

Abstract

The present application relates to a kind of graphene coating for zirconium tube coating and its preparation and application, the coating includes isopropanol as main solvent, graphene as main substrate, not more than 10% of cosolvent, not more than 2% of dispersant, not more than 10% of thickening agent, and not more than 2% of rheological agent, and the content of graphene is not less than 15% of coating mass.Compared with the prior art, the present application forms a layered peeling graphene coating on the surface of zirconium tube by coating and ablation, plays a lubricating role, at the same time reduces the stress of zirconium tube during work, and the impurity content meets the requirements for use in nuclear reactor.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of coating preparation, and relates to graphene coating for zirconium tube coating and preparation and application thereof. BACKGROUND

[0002] The research on the zirconium protective cladding in nuclear reactors is an area of concern for scientists, and it has been widely studied by coating a graphite layer or a siloxane layer on the surface of the zirconium cladding or lining a layer of pure zirconium or copper to reduce the stress of the zirconium cladding during operation. In the technical data disclosed at home and abroad, Chinese patent CN102558986B discloses a heavy water reactor fuel cladding graphite emulsion coating and a preparation method thereof, which uses 10-micron graphite powder and adopts a low-temperature film-forming agent without peeling effect. Chinese patent CN1159728C discloses a protective coating for reducing stress corrosion cracking of a zirconium alloy fuel cladding, which is characterized by using graphite as a matrix and adding zirconium oxide and ethyl cellulose to achieve the effect of a sacrificial layer. Theoretical research shows that different particle graphite materials have completely different friction mechanisms under helium and high-temperature conditions, and therefore the application research on different graphite materials for manufacturing a coating for zirconium tubes has important application value. Graphene is a new type of material, and has properties such as ductility, electrical conductivity and high thermal conductivity, and its commercialization and practical application have attracted great attention from the engineering community. The application of graphene to the manufacture of a zirconium alloy protective coating can fully exert the properties of graphene and has high practical value. However, the coating not only needs to have a certain bonding strength near the joint surface layer, but also needs to be able to normally peel off layer by layer during use. The conventional adhesive type graphite emulsion cannot be applied to the coating of special zirconium tubes. SUMMARY

[0003] The purpose of the present application is to provide a graphene coating for zirconium tube coating and preparation and application thereof, which can play a lubricating role and reduce the stress of the zirconium tube during operation when used for zirconium tube coating.

[0004] The purpose of the present application can be achieved by the following technical solutions.

[0005] One of the technical solutions of the present application provides a graphene coating for zirconium tube coating, characterized in that it comprises isopropyl alcohol as a main solvent, graphene as a main base material, not more than 10% of a cosolvent, not more than 2% of a dispersing agent, not more than 10% of a thickening agent, and not more than 2% of a rheological agent, and the content of the graphene is not less than 15% of the mass of the coating.

[0006] Further, the morphology of the graphene is a sheet structure with a diameter of no more than 1 micron and a thickness of no more than 40 nanometers. The present application adopts natural flake graphite with a purity of 99.9% purchased on the market, and further adopts ultra-low temperature liquid nitrogen freezing and grinding to obtain graphene powder. The grinding process is carried out in a frozen ball mill. The operating process conditions of the grinding process are as follows: using n-heptane as a medium, preparing a solution with a graphite content of no less than 30% of the total mass, freezing with liquid nitrogen, ball milling at a linear speed of no less than 2 m / s, ball milling for no less than 4 hours, and drying after ball milling.

[0007] Further, the cosolvent is one or more of benzyl alcohol, ethylene glycol, n-butanol, ethyl acetate, and hexylene glycol, which mainly adjusts the surface tension of the system and improves the thermal stability of the system.

[0008] Further, the dispersant is one or more of isopropyl palmitate, stearic acid monoglyceride, sorbitol fatty acid ester, octadecylamine, and titanate.

[0009] Further, the thickening agent is one or more of cellulose acetate butyrate, ethyl cellulose, hydroxyethyl ethyl cellulose, and alkyd resin.

[0010] Further, the rheological agent is one or more of carbon black, white carbon black, polyethylene wax, and heavy calcium carbonate.

[0011] Under the joint action of the dispersant and the thickening agent, the graphene powder is well wrapped and suspended in the solvent system mainly composed of isopropyl alcohol, and can maintain a stable state for a long time. At the same time, under the joint action of the appropriate thickening agent and rheological agent, the paint can meet the use conditions of the air flow spraying process, and a 10-micron-thick coating layer is stably attached to the surface of the zirconium tube through air flow spraying.

[0012] The second technical solution of the present application provides a preparation method of a graphene paint for zirconium tube coating, characterized in that the main solvent is mixed and stirred with the cosolvent, and then the graphene, the dispersant, the thickening agent, and the rheological agent are sequentially added and stirred and dispersed uniformly to obtain the graphene paint.

[0013] Further, the stirring and dispersing process specifically includes: first, backflow stirring in a stirring mill for 30 minutes, and then backflow dispersing in a vertical centrifugal dispersion sand mill for 360 minutes.

[0014] The second technical solution of the present application provides an application of a graphene paint for zirconium tube coating. The graphene paint is coated on the surface of the zirconium tube through the air flow spraying process, and forms a graphene coating layer after ablation. Specifically, the impurity content of the coating layer meets the requirements for use in a nuclear reactor, specifically, the combined content of halogen elements is no more than 50 ppm, the combined content of alkali metal elements is no more than 500 ppm, and the combined content of metal elements is no more than 5000 ppm. Further, the ablation temperature is 400℃.

[0015] The present application adopts flaky graphite with a diameter of not more than 1 micron and a thickness of not more than 40 nanometers, and the coating itself is fine and lubricating, has good fluidity, and can fully cover the substrate during the coating process. The coating formed after ablation is smooth and firm, and the lubricating effect of graphite is fully exerted. Meanwhile, the coating has the characteristics of layer peeling, and the complete ablation of organic matter is achieved through the use of the coating process, thereby meeting the use requirements of the coating in a nuclear reactor. DETAILED DESCRIPTION

[0016] The present application will be described in detail below in combination with specific examples. The present application is implemented on the premise of the technical solution of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following examples.

[0017] In the following examples, the graphene used is prepared in the following manner: commercially available natural flake graphite (Ningbo Luofei Nanometer Technology Co., Ltd., 99.9% purity) is purchased, a solution with a graphite content of about 40% of the total mass is prepared with n-heptane as the medium, the solution is frozen with liquid nitrogen, the ball milling speed is 2 meters / second, the ball milling time is 4 hours, and the ball-milled product is dried.

[0018] Example 1

[0019] Isopropyl alcohol 60%, n-butanol 5%, ethyl acetate 5%, isopropyl palmitate 1%, stearic acid monoglyceride 1%, titanate 1%, hydroxyethyl ethyl cellulose 9%, white carbon black 2%, and graphene 16%.

[0020] Isopropyl alcohol 60%, n-butanol 5%, ethyl acetate 5%, isopropyl palmitate 1%, stearic acid monoglyceride 1%, titanate 1%, hydroxyethyl ethyl cellulose 9%, white carbon black 2%, and graphene 16%.

[0021] Example 2

[0022] Isopropyl alcohol 60%, n-butanol 5%, ethyl acetate 5%, isopropyl palmitate 1%, stearic acid monoglyceride 1%, titanate 1%, hydroxyethyl ethyl cellulose 9%, white carbon black 2%, and graphene 16%.

[0023] In the container in turn pour isopropanol 300 grams, n-butanol 25 grams, ethylene glycol 25 grams, stirring, in turn add graphene 80 grams, octadecylamine 10 grams, titanate 2.5g, alkyd resin 10 grams, cellulose acetate butyrate 37.5 grams, polyethylene wax 10 grams, stirring, pour into the reflux stirring mill 30 minutes, discharge, pour into the vertical centrifugal dispersion sand mill reflux dispersion 360 minutes, discharge.

[0024] Example 3

[0025] Isopropyl alcohol 60%, benzyl alcohol 5%, hexanediol 5%, sorbitol fatty acid ester 2%, ethyl cellulose 10%, carbon black 1%, heavy calcium carbonate 1%, graphene 16%.

[0026] In the container in turn pour isopropanol 300 grams, benzyl alcohol 25 grams, hexanediol 25 grams, stirring, in turn add graphene 80 grams, sorbitol fatty acid ester 10 grams, ethyl cellulose 50 grams, carbon black 5 grams, heavy calcium carbonate 5 grams, stirring, pour into the reflux stirring mill 30 minutes, discharge, pour into the vertical centrifugal dispersion sand mill reflux dispersion 360 minutes, discharge.

[0027] The above examples passed the experimental detection, the friction coefficient is less than 0.3; in the detection can form a firm combination with zirconium tube, with ordinary napkin, no obvious peeling; has good delamination effect, can be used with transparent tape paper multiple delamination peeling attached to the surface of the zirconium tube coating, each peeling amount is not more than 50% of the inventory, basically meet the use conditions of reducing the working stress of zirconium tube, preventing microcracks.

[0028] Comparative example 1:

[0029] Most of the same as example 1, except that the graphene is replaced by conventional market natural flake graphite (Ningbo Luofei Nanometer Technology Co., Ltd., 500 nanometers, 99.9% purity).

[0030] Experimental detection can not form a firm combination with zirconium tube, wiping peeling, and its granularity is obvious.

[0031] Comparative example 2:

[0032] Most of the same as example 1, except that the graphene is replaced by conventional market natural flake graphite (Ningbo Luofei Nanometer Technology Co., Ltd., 500 nanometers, 99.9% purity).

[0033] Experimental detection can not form a high solid content solution, low content solution is expressed as high viscosity paste, not meet the use requirements of air flow spraying process.

[0034] Comparative example 3:

[0035] Compared with Example 1, most of them are the same, except that the graphite powder is obtained by the following process: purchasing commercially available natural flake graphite (Ningbo Luofei Nanometer Technology Co., Ltd., 99.9% purity), ball milling treatment in a ball mill, the operating process conditions of the grinding process are: using n-heptane as medium, preparing a solution with graphite content not less than 30% of the total mass, not using liquid nitrogen freezing, ball milling linear speed not less than 2 meters / second, ball milling time not less than 4 hours. After ball milling, drying. That is, in this comparative example, except that no freezing is performed during the ball milling process, the rest is the same as the ball milling process used in Example 1.

[0036] Experimental tests have not been able to form a firm combination with the zirconium tube, wiping off and peeling off, at the same time, its granularity is obvious. That is, without freezing during the ball milling process, the graphite powder has not been able to achieve the ideal morphology.

[0037] The above description of the examples is to facilitate the ordinary skilled person in the art to understand and use the invention. Those skilled in the art can obviously make various modifications to these examples easily, and apply the general principles described herein to other examples without having to go through creative labor. Therefore, the present invention is not limited to the above examples, and the improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A graphene coating for zirconium tube coating, characterized in that, It includes isopropanol as the main solvent, graphene as the main substrate, a co-solvent with a mass fraction of no more than 10%, a dispersant with a mass fraction of no more than 2%, a thickener with a mass fraction of no more than 10%, and a rheology modifier with a mass fraction of no more than 2%, wherein the mass fraction of the graphene is no less than 15%. The graphene is a sheet-like structure with a diameter of no more than 1 micrometer and a thickness of no more than 40 nanometers, and is prepared through the following process: Graphene powder was obtained by cryogenic grinding of 99.9% pure natural flake graphite using liquid nitrogen at ultra-low temperature. The grinding process was carried out in a cryogenic ball mill. The operating conditions of the grinding process were as follows: a solution with a graphite content of not less than 30% of the total mass was prepared using n-heptane as the medium, liquid nitrogen was used for freezing, the ball milling linear speed was not less than 2 m / s, the ball milling time was not less than 4 hours, and the powder was dried after ball milling.

2. The graphene coating for zirconium tube coating according to claim 1, characterized in that, The rheology modifier is one or more of carbon black, silica, polyethylene wax, and heavy calcium carbonate.

3. The graphene coating for zirconium tube coating according to claim 1, characterized in that, The co-solvent is one or more of benzyl alcohol, ethylene glycol, n-butanol, ethyl acetate, and hexanediol; The dispersant is one or more of isopropyl palmitate, glyceryl stearate, sorbitol fatty acid ester, octadecylamine, phthalate, aluminum chelate and zirconium aluminum oxide; The thickener is one or more of cellulose acetate butyrate, ethyl cellulose, hydroxyethyl ethyl cellulose, and alkyd resin.

4. A method for preparing a graphene coating for zirconium tubes as described in any one of claims 1-3, characterized in that, First, mix the main solvent and co-solvent evenly, then add graphene, dispersant, thickener and rheology modifier in sequence, and stir to disperse evenly to obtain graphene coating.

5. The method for preparing a graphene coating for zirconium tube coating according to claim 4, characterized in that, The specific process of stirring and dispersing is as follows: first, reflux stirring in a stirred mill for 30 minutes, and then reflux dispersion in a vertical centrifugal dispersion mill for 360 minutes.

6. The application of the graphene coating for zirconium tube coating as described in any one of claims 1-3, characterized in that, The graphene coating is applied to the surface of the zirconium tube using an airflow spraying process, and forms a graphene coating after ablation.

7. The application of the graphene coating for zirconium tube coating according to claim 6, characterized in that, The ablation temperature is 400℃.