Graphite coating material with transition layer and coating process thereof

Abstract

The present application relates to a kind of graphite coating material with transition layer and its coating process, the graphite coating material with transition layer is composed of transition layer primer, finish.In the surface of metal is coated with transition layer primer, microwave high-temperature sintering furnace is sintered, carbon-metal distribution gradient in transition layer primer is fixed, so that the impurity content from the surface of metal to the surface of transition layer primer rapidly reduces;Vacuum ablation is carried out after finish is sprayed on the surface of transition layer primer, the graphite coating material with transition layer is obtained.Compared with prior art, the present application is better controlled by two layers of coating, impurity content.

Description

Technical Field

[0001] This invention relates to the field of graphite coatings, and in particular to a graphite coating material with a transition layer and its coating process. Background Technology

[0002] Graphite coatings are widely used in aerospace, machinery manufacturing, automotive manufacturing, electronics, and energy industries due to their excellent high-temperature resistance, electrical conductivity, thermal conductivity, lubricity, and chemical stability. Their main function is to form a dense, uniform graphite film on the material surface, achieving lubrication, wear resistance, and high-temperature resistance. In current technologies, single-layer coatings are typically used when applied to metal substrates. However, graphite coatings usually require very high purity. If impurities are present, defects are easily introduced into the single-layer coating structure, making it impossible to prevent corrosive media from penetrating the substrate and causing failure. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art by providing a graphite coating material with a transition layer and its coating process. Through a specific coating process, the adhesion between the coating and the substrate is improved. By using a two-layer coating, the impurity content can be better controlled, ensuring that the surface performance of the coating meets requirements.

[0004] The objective of this invention can be achieved through the following technical solutions:

[0005] One aspect of the present invention provides a graphite coating material with a transition layer, the graphite coating material with a transition layer being composed of a transition layer primer and a topcoat;

[0006] The transition layer primer comprises the following components in parts by weight:

[0007] 15-20 parts of graphite

[0008] 0-1 part of film-forming aid

[0009] 12-18 parts of cosolvent

[0010] 1-3 parts of dispersant

[0011] Thickener 7-11 parts

[0012] 2-4 parts of coupling agent

[0013] 1-3 parts rheology modifier, and

[0014] Solvent 55-65 parts.

[0015] The topcoat comprises the following components in parts by weight:

[0016] 15-20 parts of graphite

[0017] 0-1 part of film-forming aid

[0018] 12-18 parts of cosolvent

[0019] 1-3 parts of dispersant

[0020] Thickener 7-11 parts

[0021] 1-3 parts rheology modifier, and

[0022] Solvent 55-65 parts.

[0023] Furthermore, the weight components of the transition layer primer are optimized as follows:

[0024] 16 portions of graphite

[0025] 10 parts of cosolvent

[0026] 2 parts dispersant

[0027] Thickener 9 parts

[0028] 3 parts of coupling agent

[0029] 2 parts rheology modifier, and

[0030] 58 parts solvent;

[0031] Furthermore, the weight components of the topcoat are optimized as follows:

[0032] 17 portions of graphite

[0033] 10 parts of cosolvent

[0034] 2 parts dispersant

[0035] Thickener 9 parts

[0036] 2 parts rheology modifier, and

[0037] 60 parts solvent.

[0038] Furthermore, the film-forming aid is propylene glycol methyl ether.

[0039] Furthermore, the co-solvent is one or more selected from n-butanol, ethyl acetate, benzyl alcohol, ethylene glycol, and hexanediol.

[0040] Furthermore, the co-solvent is preferably n-butanol and ethyl acetate, and the mass ratio of n-butanol to ethyl acetate is 1:1.

[0041] Furthermore, the dispersant is one or more of glyceryl monostearate, isopropyl palmitate, sorbitol fatty acid ester, octadecylamine, and phthalate.

[0042] Furthermore, the dispersant is preferably glyceryl monostearate and isopropyl palmitate, wherein the mass ratio of glyceryl monostearate to isopropyl palmitate is 1:1.

[0043] Furthermore, the thickener is one or more of hydroxyethyl ethyl cellulose, cellulose acetate butyrate, ethyl cellulose, and alkyd resin.

[0044] Furthermore, the thickener is preferably hydroxyethyl ethyl cellulose.

[0045] Furthermore, the rheology modifier is one or more of silica, carbon black, polyethylene wax, and heavy calcium carbonate.

[0046] Furthermore, the rheology modifier is preferably silica.

[0047] Furthermore, the solvent is isopropanol.

[0048] The second aspect of the present invention provides a process for implementing the graphite coating material with the transition layer, comprising the following steps:

[0049] After coating the metal surface with a transition layer primer, the metal is cured and sintered in a microwave high-temperature sintering furnace to fix the carbon-metal distribution gradient in the transition layer primer, thereby reducing the impurity content from the metal surface to the transition layer primer surface. After spraying a topcoat on the transition layer primer surface, vacuum ablation is performed to obtain the graphite coating material with the transition layer.

[0050] Furthermore, the metal is one of zirconium, aluminum, and titanium.

[0051] Furthermore, when the metal is zirconium, the coupling agent is zirconate ester; when the metal is aluminum, the coupling agent is aluminate ester; and when the metal is titanium, the coupling agent is titanate ester.

[0052] Furthermore, the sintering temperature is 1100-1300℃ and the sintering time is 5-15 min; the vacuum ablation temperature is 350-450℃ and the vacuum ablation time is 30-60 min.

[0053] Compared with the prior art, the present invention has the following advantages:

[0054] (1) This invention proposes a graphite coating material with a gradient transition layer, which improves the adhesion between the coating and the substrate through a specific implementation process. By applying two layers, the surface properties of the coating can meet the requirements because the topcoat does not contain metallic impurities introduced by coupling agents.

[0055] (2) The coupling agent used in this invention contains two types of active groups in its molecules: one type interacts with the surface of graphite particles; the other type entangles with thickener molecules, thereby creating a coupling effect between the graphite particles and the thickener, resulting in a tight bond. The ester coupling agent of the same metal exhibits a gradient distribution in the coating, with a high concentration closer to the metal and a low concentration further away, promoting the formation of a gradient transition layer. Attached Figure Description

[0056] Figure 1 This is a photograph of the actual product used in the tape experiment of Embodiment 1 of the present invention;

[0057] Figure 2 This is a physical image of the tape experiment conducted in Comparative Example 1 of this invention. Detailed Implementation

[0058] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Unless otherwise specified, all raw materials used in the present invention are commercially available or can be prepared using conventional methods in the art.

[0059] Example 1

[0060] A graphite coating material for zirconium tubes is disclosed. The topcoat consists of 17% graphite, 60% isopropanol, 9% hydroxyethyl ethyl cellulose, 2% silica, 5% n-butanol, 5% ethyl acetate, 1% isopropyl palmitate, and 1% glyceryl monostearate. The transition layer primer, with an additional 3% zirconate coupling agent, comprises 16% graphite, 58% isopropanol, 9% hydroxyethyl ethyl cellulose, 2% silica, 5% n-butanol, 5% ethyl acetate, 1% isopropyl palmitate, 1% glyceryl monostearate, and 3% zirconate coupling agent. After applying the transition layer primer to the zirconium tube surface, it is immediately sintered at 1200°C for 10 minutes in a microwave high-temperature sintering furnace. After cooling, it is coated onto the transition layer using an airflow spraying process and then vacuum ablated at 400°C for 60 minutes to form a satisfactory graphite coating. Inductively coupled plasma optical emission spectrometry (ICP-OES) analysis shows that the combined surface impurity element content is no greater than 500 ppm. Compared to surfaces with only a primer coating, the impurity elements are 1000 ppm.

[0061] Comparative Example 1

[0062] Compared to Example 1, the transition layer primer does not contain an additional 3% zirconate coupling agent.

[0063] Adhesive tape tests were conducted on the graphite coating materials prepared in Example 1 and Comparative Example 1. 3M tape was peeled off from one side of the sample. If a relatively uniform layer of graphite slightly adhered to the tape, and most of the graphite remained on the tube wall, the adhesion was good; if the graphite was completely removed by the tape, the adhesion was poor.

[0064] from Figure 1 and Figure 2 It can be seen that the graphite coating with added coupling agent has better adhesion to the substrate than the graphite coating without added coupling agent.

[0065] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A graphite coating material with a transition layer, characterized by, The graphite coating material with transition layer is coated on the metal surface, and the graphite coating material with transition layer is composed of a transition layer primer and a topcoat; The transition layer primer comprises the following components in parts by weight: Graphite 15-20 parts, Film forming aid 0-1 part, Co-solvent 8-12 parts, Dispersant 1-3 parts, Thickening agent 7-11 parts, Coupling agent 2-4 parts, Rheological agent 1-3 parts, and Solvent 55-65 parts; The topcoat comprises the following components in parts by weight: Graphite 15-20 parts, Film forming aid 0-1 part, Co-solvent 12-18 parts, Dispersant 1-3 parts, Thickening agent 7-11 parts, Rheological agent 1-3 parts, and Solvent 55-65 parts; The metal is one of zirconium, aluminum or titanium; when the metal is zirconium, the coupling agent is zirconate; when the metal is aluminum, the coupling agent is aluminate; when the metal is titanium, the coupling agent is titanate; The active groups in the molecules of the coupling agent respectively act on the surfaces of graphite particles and entangle with the molecules of the thickening agent, so that coupling occurs between the graphite particles and the thickening agent, and they are tightly combined, thereby improving the adhesion of the coating to the substrate; Through two-layer coating, since the topcoat does not contain metal impurities introduced by the coupling agent, the impurity content is better controlled, and the surface performance of the coating meets the requirements.

2. The graphite coating material with a transition layer according to claim 1, characterized in that, The film forming aid is propylene glycol methyl ether.

3. The graphite coating material with a transition layer according to claim 1, characterized in that, The co-solvent is one or more of n-butanol, ethyl acetate, benzyl alcohol, ethylene glycol or hexylene glycol.

4. The graphite coating material with a transition layer according to claim 1, characterized in that, The dispersant is one or more of glycerol monostearate, isopropyl palmitate, sorbitol fatty acid ester, octadecylamine or phthalate.

5. The graphite coating material with a transition layer according to claim 1, characterized in that, The thickening agent is one or more of hydroxyethyl ethyl cellulose, cellulose acetate butyrate, ethyl cellulose or alkyd resin.

6. The graphite coating material with a transition layer according to claim 1, characterized in that, The rheological agent is one or more of white carbon black, carbon black, polyethylene wax or heavy calcium carbonate.

7. The graphite coating material with a transition layer according to claim 1, characterized in that, The solvent is isopropyl alcohol.

8. The graphite coating material with a transition layer according to claim 1, characterized in that, The transition layer primer comprises the following components in parts by weight: Graphite 16 parts, Co-solvent 10 parts, Dispersant 2 parts, Thickening agent 9 parts, Coupling agent 3 parts, Rheological agent 2 parts, and Solvent 58 parts; The topcoat comprises the following components in parts by weight: Graphite 17 parts, Co-solvent 10 parts, Dispersant 2 parts, Thickening agent 9 parts, Rheological agent 2 parts, and Solvent 60 parts.

9. A coating process for a graphite coating material with a transition layer as claimed in any one of claims 1-8, characterized in that, The method comprises the following steps: After the transition layer primer is coated on the metal surface, it is cured and sintered in a microwave high-temperature sintering furnace to fix the carbon-metal distribution gradient in the transition layer primer, so that the impurity content decreases from the metal surface to the surface of the transition layer primer; after the topcoat is sprayed on the surface of the transition layer primer, vacuum ablation is performed, and the graphite coating material with transition layer is obtained.

10. The coating process of a graphite coating material with a transition layer according to claim 9, characterized in that, The sintering temperature is 1100-1300 ℃, and the sintering time is 5-15 min; the vacuum ablation temperature is 350-450 ℃, and the vacuum ablation time is 30-60 min.

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