Method for preparing low-high temperature cycle PTFE coating on surface of aluminum alloy and application of low-high temperature cycle PTFE coating

Abstract

The invention relates to a method for preparing a coating on the surface of an aluminum alloy, in particular to a method for preparing a low-high temperature circulating PTFE coating on the surface of the aluminum alloy and application. The invention aims to solve the problems that the requirements of the existing hydrogen fuel cell system environment on the heat resistance, wear resistance and corrosion resistance of parts in the system are high, and the method for preparing coatings on the surfaces of the parts by using the existing method is complicated and high in cost, and the coatings are not resistant to corrosion. The method comprises the following steps: 1, pretreating a base material; 2, the PTFE coating is stirred; 3, the PTFE coating is sprayed to the surface of the base material; and 4, baking and curing. The prepared PTFE coating is black, the thickness is 0.03-0.05 mm, and a spraying material is firmly combined with a base material and does not peel or fall off; the acid resistance pH is 4-6, the humidity resistance is 0-100%, and no white rust is generated after a neutral salt spray test is performed for 144 hours; the cable can resist the temperature of-40 DEG C to 125 DEG C and is aging-resistant.

Description

Technical Field

[0001] The invention relates to a method for preparing a coating on the surface of an aluminum alloy. Background Art

[0002] A fuel cell system refers to a power generation system with fuel cells as the core. In addition to the fuel cell body (power generation system), the system also has some peripheral devices, including fuel reforming supply system, oxygen supply system, water management system, thermal management system, DC-AC inverter system, control system, safety system, etc. Therefore, the fuel cell system is a very complex power generation system. At the same time, there are many kinds of fuel cell systems, and the common ones are hydrogen fuel cell systems, methanol fuel cell systems, ammonia fuel cell systems, metal air fuel cell systems, etc. There are great differences in the principles, structures, materials, etc. of these fuel cell systems. Among all fuel cell systems, the hydrogen fuel cell system is the most studied power generation system. It is an advanced energy conversion technology that converts chemical energy into electrical energy. It uses hydrogen and oxygen as fuels, generates electrical energy through the reduction reaction of hydrogen and oxidation, and uses water as the only emission. It has the characteristics of high efficiency, cleanliness, and environmental protection, and is regarded as one of the mainstream technologies of green energy in the future. It has been widely used in transportation, aerospace, mobile power supply and other fields.

[0003] However, there are still many challenges in the development of hydrogen fuel cell systems. The problems faced by hydrogen fuel cell systems include: thermal management, life, cost, etc. In order to solve these problems, the research and development of hydrogen fuel cell systems needs to use new technologies, new materials, new structures and other means. For example, the use of new coating protection, new catalysts, improved fuel cell structure, and the introduction of intelligent control technology are all important means to improve the performance of hydrogen fuel cell systems. The storage and transportation of hydrogen fuel is also more complicated than traditional fuels, and it is crucial to ensure the safety and reliability of hydrogen. Therefore, the development of hydrogen storage and transportation systems with high safety and reliability is also an urgent problem to be solved. In addition, the relatively high cost of producing hydrogen fuel cells also limits the development of their large-scale applications. Therefore, optimizing the manufacturing process of hydrogen fuel cells and reducing costs are the current research focuses, especially in the complex environment of hydrogen fuel cell systems, the high temperature resistance, wear resistance, and corrosion resistance of components have always been the key to the safe and reliable operation of hydrogen fuel cell systems. At present, most of the components of hydrogen fuel cell systems are made of aluminum alloy, such as electronic throttle valves and other parts, but due to their complex working environment, their high temperature resistance, wear resistance, and corrosion resistance need to be further improved.

[0004] The existing invention patent application "Catalyst proton membrane coating and its preparation method, membrane electrode, fuel cell" CN 118231684A is aimed at electrodes, using catalyst protons to prepare catalyst PTFE coating membranes, and the temperature resistance range of the membrane layer can only be 280℃~320℃. "A method for surface modification of microporous layer of gas diffusion layer for fuel cells" CN 118198383A is aimed at proton exchange membranes, a method for surface modification of microporous layer of gas diffusion layer for fuel cells, preventing and controlling the degradation of proton exchange membranes and improving the durability of fuel cell membrane electrodes. The utility model patent "A DC motor dedicated to fuel cell throttle valve" CN219145219U does not involve PTFE coatings or fuel cell system components, but only provides a dedicated DC motor for fuel cell valves. There is currently no relevant patent disclosure for a method for preparing low-high temperature cycle PTFE coatings on the surface of aluminum alloy components of hydrogen fuel cell systems.

[0005] The internal medium flow environment of the hydrogen fuel cell engine system is complex, including hydrogen, wet steam, air, liquid water and coolant. Many of the parts they flow through are metal products, such as pipe joints, end plates of the stack, power boards, etc., mostly made of aluminum, stainless steel or copper. If corrosion occurs in the gas path, such as stainless steel or copper, it will release multivalent metal cations that diffuse into the membrane and Nafion resin in the CL. When combined with sulfonic acid groups, it will cause a decrease in ionic conductivity, such as Fe 2+It will also accelerate the generation of hydroxyl free radicals, further increasing the chemical attenuation of Nafion; if the various ions released enter the cooling water channel, it will cause the conductivity of the water channel to increase and the insulation performance to decrease. At present, the hydrogen fuel cell industry commonly uses the following surface coating strengthening technologies to deal with these problems: such as electroplating, which uses electrolysis to attach a layer of metal or alloy film to the surface of metal or other material parts, thereby preventing metal oxidation (such as rust), improving wear resistance, conductivity, reflectivity, corrosion resistance and enhancing aesthetics. In addition to iron-based cast iron, steel and stainless steel, the base materials for electroplating also include non-ferrous metals, ABS plastics, polypropylene, polysulfone and phenolic plastics, but plastics must undergo special activation and sensitization treatment before electroplating. The electroplating layer is generally thin, ranging from a few microns to tens of microns. The commonly used plating metals are zinc plating, cadmium plating, nickel plating, gold plating, silver plating, chrome plating, etc. Common failure manifestations of electroplating layers include delamination, cracking, corrosion, blistering, coating / plating shedding, discoloration, etc., which are all related to the electroplating process, including the selection and pretreatment of the substrate, the internal stress of the substrate, the impurity content of the electroplating solution, the thickness of the coating, the current size, and the process parameters, etc. Another is anodizing. For example, the commonly used aluminum anodizing is the process in which aluminum and its alloys form an oxide film on aluminum products under the corresponding electrolyte and specific process conditions due to the action of an external current. Anodizing of aluminum products is to overcome the defects of aluminum alloy surface hardness, wear resistance, etc., expand the scope of application, and extend the service life. Surface treatment technology has become an indispensable part of the use of aluminum alloys. The metal oxide film changes the surface state and properties, such as surface coloring, improving corrosion resistance, enhancing wear resistance and hardness, and protecting the metal surface. The aluminum or its alloy of the anode is oxidized, and a thin layer of aluminum oxide is formed on the surface, with a thickness of 5 to 30 microns, and the hard anodized film can reach 25 to 150 microns. After anodizing, aluminum or its alloy has improved its hardness and wear resistance, which can reach 250-500 kg / mm2. It has good heat resistance, the melting point of hard anodized film is as high as 2320K, excellent insulation, and the breakdown voltage is as high as 2000V, which enhances the corrosion resistance and does not corrode in salt spray for thousands of hours. However, waste liquid and waste gas are generated during the anodizing process, which contain a large amount of harmful substances such as fluoride and chromic acid, causing certain pollution and harm to the environment. These waste liquids and waste gases also need to be treated with special treatment methods, which increases the environmental protection cost. At the same time, the effect of anodizing is affected by many factors, such as electrolyte concentration, voltage, temperature, time, etc. If these parameters are not well controlled, the anodizing effect will be unstable or even fail. Summary of the invention

[0006] The purpose of the present invention is to solve the problems that the existing hydrogen fuel cell system environment has high requirements on the heat resistance, wear resistance and corrosion resistance of the internal components of the system, the existing method for preparing coatings on the surface of its components is complex, costly, and the coatings are not corrosion-resistant, and to provide a method and application for preparing a low-high temperature cyclic PTFE coating on the surface of an aluminum alloy.

[0007] A method for preparing a low-high temperature cyclic PTFE coating on an aluminum alloy surface is specifically prepared according to the following steps:

[0008] 1. Pretreatment of substrate:

[0009] The surface of the substrate is cleaned, and then placed in a high temperature box for high temperature treatment for a period of time to obtain a pretreated substrate;

[0010] 2. Stir the PTFE coating until the precipitate at the bottom completely disappears, and then filter it with a filter to remove the precipitate to obtain a uniformly mixed PTFE coating;

[0011] 3. spraying the evenly mixed PTFE coating evenly onto the surface of the pretreated substrate to obtain a substrate sprayed with PTFE coating;

[0012] Fourth, the substrate sprayed with PTFE coating is placed in a high temperature box for baking and curing, so as to obtain a low-high temperature cycle PTFE coating on the surface of the aluminum alloy.

[0013] The low-high temperature cycle PTFE coating is used in internal parts of hydrogen fuel cell systems.

[0014] Principle of the present invention:

[0015] 1. PTFE, also known as polytetrafluoroethylene, is also known as the "King of Plastics". It is a polymer compound formed by the polymerization of tetrafluoroethylene. Its chemical formula is (C 2 F 4)n. PTFE has a series of excellent properties and is increasingly being used in various fields. Such as non-stickiness, heat resistance, sliding, low friction coefficient, moisture resistance, wear resistance, corrosion resistance, etc. Almost all substances do not adhere to the polytetrafluoroethylene coating. Very thin films also show good non-stick properties. The polytetrafluoroethylene coating has excellent heat and low temperature resistance. It can work at freezing temperatures without becoming brittle and does not melt at high temperatures. The polytetrafluoroethylene coating has a relatively. The friction coefficient changes when the load slides, but the value is only between 0.05-0.15. The surface of the polytetrafluoroethylene coating does not stick to water and oil, and it is not easy to stick to the solution during production operation. If there is a small amount of dirt, it can be removed by simply wiping. The downtime is short, saving work hours and improving work efficiency. Under high load, it has excellent wear resistance. Under a certain load, it has the dual advantages of wear resistance and non-stick. Polytetrafluoroethylene is almost immune to chemical corrosion and can withstand all strong acids (including aqua regia), strong oxidants, reducing agents and various organic solvents except molten alkali metals, fluorinated media and sodium hydroxide above 300°C, and can protect parts from any kind of chemical corrosion. In summary, the use of a series of excellent properties of PTFE can effectively improve the high temperature resistance, wear resistance and corrosion resistance of hydrogen fuel cell system components to ensure the stability and safety of hydrogen fuel cell systems.

[0016] Second, the PTFE coating of the present invention has the following advantages: First, low-temperature use. The PTFE coating of the present invention can be used continuously and safely at a temperature of -40°C. Second, high-temperature use. The PTFE coating of the present invention can be used continuously and safely at a temperature of 125°C. Third, the reliability of the PTFE coating of the present invention can meet the requirements of Yankee, vibration, corrosion and durability of automotive standards.

[0017] Advantages of the present invention:

[0018] 1. Aiming at the three key problems of high temperature resistance, wear resistance and corrosion resistance that plague aluminum alloy parts of existing hydrogen fuel cell systems, the present invention proposes a new technology for designing and developing coatings for parts of hydrogen fuel cell systems: using a series of excellent properties of PTFE to achieve effective protection of aluminum alloy parts of hydrogen fuel cell systems;

[0019] 2. The PTFE coating of the aluminum alloy parts of the hydrogen fuel cell system developed by the present invention can be recycled in the temperature range of -40℃ to 125℃, and has excellent aging resistance;

[0020] 3. The PTFE coating of the aluminum alloy parts of the hydrogen fuel cell system developed by the present invention is black in color and 0.03-0.05mm in thickness; the spraying material is firmly bonded to the shell and cannot peel off;

[0021] 4. The PTFE coating of the aluminum alloy parts of the hydrogen fuel cell system developed by the present invention has an acid resistance of pH 4 to 6 and a humidity resistance of 0 to 100% neutral salt spray test for 144 hours without white rust;

[0022] 5. All spraying materials of the PTFE coating of the aluminum alloy parts of the hydrogen fuel cell system developed by the present invention meet the requirements of GB / T 30512 for prohibited substances.

[0023] The invention is applicable to the preparation requirements of metal PTFE coatings in all low-high temperature cyclic corrosion environments at -40°C to 125°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a front view of preparing a PTFE coating on the surface of an aluminum alloy component in Example 1;

[0025] Figure 2 This is a bottom view of preparing a PTFE coating on the surface of an aluminum alloy component in Example 1;

[0026] Figure 3 The gas passage for preparing the PTFE coating on the surface of the aluminum alloy part in Example 1 needs to focus on the spraying area;

[0027] Figure 4 In Example 1, when preparing PTFE coating on the surface of aluminum alloy parts, it is necessary to protect the parts that cannot be sprayed;

[0028] Figure 5 For Example 1, the PTFE coating is prepared on the surface of the aluminum alloy parts at both ends of the flange surface sealing surface, and the surface cannot have convex or concave defective parts;

[0029] Figure 6 The surface morphology and cross-sectional characteristics of the PTFE coating prepared on the surface of the aluminum alloy part in Example 1;

[0030] Figure 7 The neutral salt spray test data results of the aluminum alloy parts and the PTFE coating prepared on the surface of the aluminum alloy parts in Example 1, in which (a) is the aluminum alloy parts, and (b) is the PTFE coating prepared on the surface of the aluminum alloy parts in Example 1;

[0031] Figure 8 The first friction and wear test data results of the aluminum alloy parts and Example 1 on the surface of the aluminum alloy parts to prepare the PTFE coating;

[0032] Fig. 9 The second friction and wear test data results for aluminum alloy parts and Example 1 in which PTFE coating is prepared on the surface of aluminum alloy parts. DETAILED DESCRIPTION

[0033] The following examples further illustrate the content of the present invention, but should not be construed as limiting the present invention. Without departing from the essence of the present invention, modifications and substitutions made to the methods, steps or conditions of the present invention all fall within the scope of the present invention.

[0034] Specific implementation method 1: This implementation method is a method for preparing a low-high temperature cyclic PTFE coating on an aluminum alloy surface, which is specifically prepared according to the following steps:

[0035] 1. Pretreatment of substrate:

[0036] The surface of the substrate is cleaned, and then placed in a high temperature box for high temperature treatment for a period of time to obtain a pretreated substrate;

[0037] 2. Stir the PTFE coating until the precipitate at the bottom completely disappears, and then filter it with a filter to remove the precipitate to obtain a uniformly mixed PTFE coating;

[0038] 3. spraying the evenly mixed PTFE coating evenly onto the surface of the pretreated substrate to obtain a substrate sprayed with PTFE coating;

[0039] Fourth, the substrate sprayed with PTFE coating is placed in a high temperature box for baking and curing, so as to obtain a low-high temperature cycle PTFE coating on the surface of the aluminum alloy.

[0040] Specific implementation method 2: This implementation method is different from specific implementation method 1 in that the substrate described in step 1 is aluminum alloy ADC12. The other steps are the same as those in specific implementation method 1.

[0041] Specific implementation method 3: This implementation method is different from specific implementation method 1 or 2 in that: in step 1, water is used as a cleaning agent and a spray gun is used to clean the surface of the substrate until the surface of the substrate is free of dust, dirt and oil stains. The other steps are the same as those of specific implementation method 1 or 2.

[0042] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the high temperature treatment time in step 1 is 280°C to 290°C and the high temperature treatment time is 30min to 40min. The other steps are the same as those in specific embodiments 1 to 3.

[0043] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that: the relative specific gravity of the PTFE coating in step 2 is 4.08±0.2 kg / gal, the model is XYLAN 1014 / P01931E, purchased from Huafu Company of the United States; in step 2, the PTFE coating is stirred at a temperature of 18°C ​​to 32°C. The other steps are the same as those in specific embodiments 1 to 4.

[0044] Specific implementation method 6: This implementation method is different from specific implementation methods 1 to 5 in that the pore size of the filter screen in step 2 is 100 μm to 200 μm. The other steps are the same as those of specific implementation methods 1 to 5.

[0045] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that the curing temperature in step 4 is 280° C. to 290° C. and the curing time is 10 min to 20 min. The other steps are the same as those in specific embodiments 1 to 6.

[0046] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that the thickness of the low-high temperature cycle PTFE coating obtained on the surface of the aluminum alloy in step 4 is 30 μm to 50 μm. The other steps are the same as those of specific embodiments 1 to 7.

[0047] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the low-high temperature cycle PTFE coating described in step 4 is smooth without protrusions and concave spots of missed spraying. The other steps are the same as those of specific embodiments 1 to 8.

[0048] Specific implementation method ten: This implementation method is the application of the low-high temperature cycle PTFE coating in the internal parts of the hydrogen fuel cell system.

[0049] The following examples are used to verify the beneficial effects of the present invention:

[0050] Example 1: A method for preparing a low-high temperature cyclic PTFE coating on an aluminum alloy surface, specifically prepared according to the following steps:

[0051] 1. Pretreatment of substrate:

[0052] The surface of the substrate is cleaned, and then placed in a high temperature box for high temperature treatment for a period of time to obtain a pretreated substrate;

[0053] The substrate described in step 1 is an aluminum alloy component in a hydrogen fuel cell system, and the material is aluminum alloy ADC12;

[0054] In step 1, the surface of the substrate is cleaned by using a spray gun until the surface of the substrate is free of dust, dirt and oil stains;

[0055] The high temperature treatment time in step 1 is 290° C.; the high temperature treatment time is 40 min;

[0056] 2. Stir the PTFE coating at a temperature of 25°C until the precipitate at the bottom completely disappears, and then filter it with a filter to remove the coagulated matter to obtain a uniformly mixed PTFE coating;

[0057] The relative specific gravity of the PTFE coating described in step 2 is 4.08±0.2 kg / gal, the model is XYLAN 1014 / P01931E, and it was purchased from Huafu Company of the United States;

[0058] The pore size of the filter described in step 2 is 150 μm;

[0059] 3. spraying the evenly mixed PTFE coating evenly onto the surface of the pretreated substrate to obtain a substrate sprayed with PTFE coating;

[0060] Fourth, the substrate sprayed with PTFE coating is placed in a high temperature box for baking and curing, and a low-high temperature cycle PTFE coating is obtained on the surface of the aluminum alloy;

[0061] The curing temperature in step 4 is 280°C and the curing time is 10 minutes;

[0062] The thickness of the low-high temperature cycle PTFE coating obtained on the aluminum alloy surface in step 4 is 50 μm;

[0063] The low-high temperature cycle PTFE coating described in step 4 is smooth without protrusions and without missed spraying pits.

[0064] Figure 1 This is a front view of preparing a PTFE coating on the surface of an aluminum alloy component in Example 1;

[0065] Figure 2 This is a bottom view of preparing a PTFE coating on the surface of an aluminum alloy component in Example 1;

[0066] Figure 3 The gas passage for preparing the PTFE coating on the surface of the aluminum alloy part in Example 1 needs to focus on the spraying area;

[0067] Figure 4 In Example 1, when preparing PTFE coating on the surface of aluminum alloy parts, it is necessary to protect the parts that cannot be sprayed;

[0068] Figure 5 For Example 1, the PTFE coating is prepared on the surface of the aluminum alloy parts at both ends of the flange surface sealing surface, and the surface cannot have convex or concave defective parts;

[0069] Figure 3 , Figure 4 , Figure 5 The protruding parts of the PTFE coating sprayed on the surface of ADC12 aluminum alloy are marked in red.

[0070] Figure 6 The surface morphology and cross-sectional characteristics of the PTFE coating prepared on the surface of the aluminum alloy part in Example 1;

[0071] from Figure 6 It can be seen that the microstructure of the PTFE coating is very uniform and dense, both on the surface and in the cross section, and the thickness of the coating interface is between 30 μm and 50 μm.

[0072] Figure 7 The neutral salt spray test data results of the aluminum alloy parts and the PTFE coating prepared on the surface of the aluminum alloy parts in Example 1, in which (a) is the aluminum alloy parts, and (b) is the PTFE coating prepared on the surface of the aluminum alloy parts in Example 1;

[0073] According to the national standard GB / T 10125-2012, the neutral salt spray test temperature is (35±2)℃, the salt concentration is (50±5)g / L, and the test time is 144 hours. Figure 7 It can be seen that after 144 hours of salt spray test, the product with PTFE coating sprayed on the surface of ADC12 aluminum alloy showed no corrosion phenomenon. The corrosion level was 7, while the ADC12 aluminum alloy parts without PTFE coating were severely corroded, and almost the entire surface of the parts was severely corroded.

[0074] Figure 8 The first friction and wear test data results of the aluminum alloy parts and Example 1 on the surface of the aluminum alloy parts to prepare the PTFE coating;

[0075] Fig. 9 The second friction and wear test data results for aluminum alloy parts and Example 1 in which PTFE coating is prepared on the surface of aluminum alloy parts.

[0076] The experimental data shows that the friction coefficient of the friction coefficient curve of the substrate has a large range of variation, with the highest value reaching 0.28 and the stable friction coefficient range of 0.20-0.23. The friction coefficient is large in the first minute and the wear value is also large. After about 1 minute, it tends to be stable. The friction coefficient curve of the PTFE coating has a small range of variation of the friction coefficient of this group, and the running-in time is also short. The highest value does not exceed 0.20, and the stable friction coefficient range is 0.15-0.18. The friction coefficient is reduced by about 25% compared with the previous group. Spraying PTFE coating on the surface can effectively reduce the friction coefficient of parts and extend the service life of parts.

Claims

1. A method for preparing a low-high temperature cyclic PTFE coating on an aluminum alloy surface, characterized in that The method is specifically prepared according to the following steps:

1. Pretreatment of substrate: The surface of the substrate is cleaned, and then placed in a high temperature box for high temperature treatment for a period of time to obtain a pretreated substrate; 2. Stir the PTFE coating until the precipitate at the bottom completely disappears, and then filter it with a filter to remove the precipitate to obtain a uniformly mixed PTFE coating; 3. spraying the evenly mixed PTFE coating evenly onto the surface of the pretreated substrate to obtain a substrate sprayed with PTFE coating; Fourth, the substrate sprayed with PTFE coating is placed in a high temperature box for baking and curing, so as to obtain a low-high temperature cycle PTFE coating on the surface of the aluminum alloy.

2. A method for preparing a low-high temperature cyclic PTFE coating on an aluminum alloy surface according to claim 1, characterized in that The substrate described in step 1 is aluminum alloy ADC12.

3. A method for preparing a low-high temperature cyclic PTFE coating on an aluminum alloy surface according to claim 1, characterized in that In step 1, water is used as a cleaning agent, and a spray gun is used to clean the surface of the substrate until the surface of the substrate is free of dust, dirt and oil stains.

4. A method for preparing a low-high temperature cyclic PTFE coating on an aluminum alloy surface according to claim 1, characterized in that The high temperature treatment time in step 1 is 280° C. to 290° C.; the high temperature treatment time is 30 min to 40 min.

5. A method for preparing a low-high temperature cyclic PTFE coating on an aluminum alloy surface according to claim 1, characterized in that The relative specific gravity of the PTFE coating described in step 2 is 4.08±0.2 kg / gal, and the model is XYLAN 1014 / P01931E; in step 2, the PTFE coating is stirred at a temperature of 18° C. to 32° C.

6. A method for preparing a low-high temperature cyclic PTFE coating on an aluminum alloy surface according to claim 1, characterized in that The pore size of the filter described in step 2 is 100 μm to 200 μm.

7. A method for preparing a low-high temperature cyclic PTFE coating on an aluminum alloy surface according to claim 1, characterized in that The curing temperature in step 4 is 280° C. to 290° C., and the curing time is 10 min to 20 min.

8. A method for preparing a low-high temperature cyclic PTFE coating on an aluminum alloy surface according to claim 1, characterized in that The thickness of the low-high temperature cyclic PTFE coating obtained on the surface of the aluminum alloy in step 4 is 30 μm to 50 μm.

9. A method for preparing a low-high temperature cyclic PTFE coating on an aluminum alloy surface according to claim 1, characterized in that The low-high temperature cycle PTFE coating described in step 4 is smooth without protrusions and without missed spraying pits.

10. Application of the low-high temperature cycle PTFE coating prepared by the preparation method according to claim 1, characterized in that The low-high temperature cycle PTFE coating is used in internal parts of hydrogen fuel cell systems.

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