A method for providing superhydrophobic properties for metal substrates

Abstract

The invention relates to a method for providing superhydrophobic properties to metal substrates suitable for use in obtaining elements that provide cooling in electronic systems, elements within supercomputers, medical instruments, space environment control devices, various tools and devices in the defense industry, drying systems in the food industry, household appliances or devices, self-cleaning products, but not limited thereto, and a metal product obtained by this method having at least one surface provided with superhydrophobic properties.

Description

[0001] DESCRIPTION

[0002] A METHOD FOR PROVIDING SUPERHYDROPHOBIC PROPERTIES FOR METAL SUBSTRATES

[0003] TECHNICAL FIELD

[0004] The invention relates to a method for providing superhydrophobic properties to metal substrates suitable for use in systems that provide cooling in electronic systems, elements within supercomputers, medical instruments, space environment control devices, various tools and devices in the defense industry, drying systems in the food industry, household appliances or devices, self-cleaning products that prevent the heating of the parts of elements, but not limited thereto, and a metal product obtained by this method having at least one surface provided with superhydrophobic properties.

[0005] PRIOR ART

[0006] Superhydrophobic property is one of the terms that describes the interaction of surfaces with water. This property is known as a property of the surface that repels liquid and promotes the formation of water droplets thereon. Superhydrophobic surfaces allow the liquid to remains as droplets on the surface or easily move away from the surface instead of dispersing. These liquid droplets leave the surface immediately and slide off the surface easily. Considering water as the liquid, water droplets take a spherical shape on such surfaces. It is known that surfaces provided with superhydrophobic properties encompass technical solutions and advantages such as self-cleaning, water repellency, providing antibacterial properties, energy saving in cooling and heat transfer devices, and providing water diversion processes.

[0007] In order to gain superhydrophobic properties for metal surfaces, firstly the cleaning processes of the surfaces must be performed. Acids are generally used for cleaning metal surfaces. The use of acids is toxic to humans or harmful to the environment. In addition, in order to provide superhydrophobic properties, several very complex process steps are applied to the surfaces and high amounts of chemicals that cause problems for the environment and human health are used. Production methods with such process steps and the use of chemicals pose a threat to both in terms of cost, human-environment health. For the relevant technical field, it is necessary to develop production processes that do not involve complex process steps, have low costs, and do not pose a threat to the environment and human health, and to carry out studies on the use of suitable chemicals.

[0008] The chemicals to be used to provide superhydrophobic properties to metal surfaces are expected to have sufficient mechanical, thermal, and corrosion resistance in technical fields where metals are used. Silane-based coating materials, for example, do not have high temperature and mechanical strength values, and they dissolve in water over time and their service life is exhausted. Although these coating materials are very popular coating materials, they are also not suitable for use in providing superhydrophobic properties to metal surfaces due to their carcinogenic properties.

[0009] Accordingly, it is essential that the coating material used to provide superhydrophobic properties to metal materials has a structure that will not pose a threat to human- environmental health.

[0010] The coating material used to provide superhydrophobic properties to metal materials is expected to have high mechanical resistance to loads, high thermal resistance to temperature, and anti-corrosive properties.

[0011] In addition, the coating material used to provide the superhydrophobic properties to metal materials being a water-resistant and chemically compatible material also affects the service life.

[0012] As a result, it is necessary to research and design suitable coating materials for providing superhydrophobic properties to metal surfaces for the relevant technical fields and methods for the application of these coating materials with high efficiency.

[0013] SUMMARY OF THE INVENTION

[0014] The present invention relates to a method to be applied for providing resilient superhydrophobic properties to metal surfaces for use in related technical fields, and to metal materials having superhydrophobic properties comprising a coating material applied by means of such methods. An object of the invention is to introduce a method for obtaining a metal surface with superhydrophobic properties by applying a coating material with a structure that does not pose a threat to human-environmental health.

[0015] An object of the invention is to introduce a method for obtaining a metal surface with superhydrophobic properties by applying a coating material with high mechanical resistance to loads, high thermal resistance to temperature, and anti-corrosive activity.

[0016] An object of the invention is to introduce a method for obtaining a metal with superhydrophobic properties by applying a water-resistant and compatible coating material.

[0017] An object of the invention is to introduce a method for obtaining metals with superhydrophobic properties, in which costs are low and complex processing steps are not required.

[0018] DETAILED DESCRIPTION OF THE INVENTION

[0019] In this detailed description, the subject of the invention relates to a method for providing at least one surface of metal substrates with superhydrophobic properties, and is described by way of non-limiting examples only for a better understanding of the subject matter.

[0020] In this invention, the aim is to provide superhydrophobic properties to at least one surface of the metal substrate. The scope of protection of the invention is independent of what the metal is; and the method of the invention and the superhydrophobic surface coating with this method can be applied to any metal material. Referring to metal in this invention, metal-based alloys such as steel, other compounds are also included in the scope of protection of this invention.

[0021] In the invention, "at least one surface" refers to the treatments related to at least one of the upper and / or lower surfaces of the metal if it is two-dimensional. The scope of protection of the invention may include performing treatments on both surfaces. Metal can also be three-dimensional; in this case, it may be possible to perform treatments on their lateral surfaces. In this invention, surface treatments mean all of the process steps applied to provide the superhydrophobic property of the invention. In this document, said process steps will be characterized.

[0022] With the provision of superhydrophobic properties, metal materials gain added value. In all places where superhydrophobic properties are required in the relevant technical fields, metal materials provided with superhydrophobic properties of the invention can be used.

[0023] The active ingredient that provides the superhydrophobic property mentioned in this invention is essentially polytetrafluoroethylene (abbreviated as PTFE) polymer material.

[0024] PTFE has a water-repellent, i.e. hydrophobic surface.

[0025] PTFE is not a carcinogenic material; and it does not create any technical disadvantage for the environment and human health.

[0026] PTFE does not dissolve or corrode in any interaction with water during the time it is in contact with it.

[0027] PTFE is a material with high thermal strength and strength values.

[0028] Due to all these technical advantages and solutions, the inventors of the present invention have determined that it is suitable to use PTFE as the active ingredient that provides the superhydrophobic property.

[0029] In this invention, a composition is introduced that provides superhydrophobic properties for metal surfaces. Said composition will then be used as a raw material in the process steps of the method to be characterized in the invention.

[0030] By composition, it is meant a solution consisting of more than one component coexisting in a stable structure. One of these components is PTFE, while the other component is isopropanol. Isopropanol, as expected, is included as a solvent in the composition. The presence of isopropanol as a solvent in the solution is critical to ensure the dissolution of PTFE and its efficient application in the production process steps. Herein, PTFE is included as a solute.

[0031] Another reason for preferring isopropanol as a solvent is that it is easy to evaporate under the ambient conditions where the method process steps are applied. In this way, while the other method process steps are applied, only PTFE remains on the metal surface.

[0032] In a preferred embodiment, PTFE in solution has nano-sized dimensions. This value is at a value in the range of 100 to 500 nm. PTFE being nano-sized in dimensions is necessary for homogeneous distribution of PTFE in the solution. In addition, when the solution is applied to metal surfaces by spraying method, the nano-sized dimension of PTFE for settling into micron-sized roughnesses on the surface provides technical advantages.

[0033] In this way, the amount of PTFE in isopropanol is also critical for obtaining a homogeneous solution. When PTFE is solid, it is present in the solution in mg levels, while isopropanol is present in liquid form and its amount in the solution is expressed in ml. Accordingly, in order to characterize the amount of PTFE in solution, it is given as the PTFE / isopropanol ratio and this value is a value between 0.5 / 10 mg / ml to 1.5 / 10 mg / ml. The reason why these values are preferred is to ensure that they are suitable for the surface area size and roughness values on the surface. The mixture prepared in these amounts can then be turned into a homogeneous mixture, preferably by a mixing process. In another preferred embodiment, the mixing process is continued until the color of the mixture changes to a light-milk color.

[0034] The method of providing superhydrophobic properties on at least one surface for the metal of the invention includes the following process steps.

[0035] Performing pre-treatments on the metal surface Said process step is performed to clean the metal surface first, but more importantly, it is for ensuring that the prepared solution can be applied to the metal surface and for obtaining micron-sized structures that can be positioned there. The dimension of structures mentioned herein is a value in the range of 20 to 100 micrometers. These values were preferred for the formation of targeted micro-structures on metal surfaces.

[0036] Here, it is important to obtain these dimensions, but the scope of protection of the invention is not limited to which method is applied. In the present invention, conventional milling, preferably with silicon carbide abrasive paper suitable for these dimensions, or laser applications can be used as a method. However the scope of protection of the invention is not limited to these methods. If preferred, these methods or more than one of the other methods known in the technique can be used.

[0037] Although the structures obtained in said dimensions are triangular and / or rectangular regular cavities, they can also be cavities of irregular shapes.

[0038] In a preferred embodiment, cleaning processes are applied again after the structures are formed. In another preferred embodiment, this cleaning process can be performed with the use of a chemical solution. This chemical solution contains at least one of the acetone, isopropanol and / or other alcohol-based compounds.

[0039] Preparation of the solution that will provide the prepared superhydrophobic properties and its application to the metal surface

[0040] The solution contains PTFE and isopropanol. The weight ratio of these components is a value between 0.5 / 10 mg / ml to 1.5 / 10 mg / ml for PTFE / isopropanoL

[0041] In this invention, the air-blast atomizer method is preferred as a technique for applying the solution to the metal surfaces. Because this method is an easy and fast technique for applying nano-sized PTFE-containing solution to metal surfaces.

[0042] The solution is filled into a reservoir connected to the nozzles of an air blast-atomizer for application to metal surfaces. Atomization pressure is applied from the nozzles to the metal surface(s) with a value in the range of 1 to 5 bar. The reason for using said pressure values is to ensure that the solution has the optimum droplet diameter during spraying processes.

[0043] The distance of the nozzles to the metal surface is a value between 20 to 50 cm.

[0044] While this process step is applied with said technique, as mentioned before, isopropanol is removed from the environment by evaporation. In this way, only PTFE nano-sized particles are positioned on the metal surface.

[0045] Pressing process to fix the position of the PTFE

[0046] A pressing process is performed on the coated surface to mechanically lock the PTFE applied to the metal surface into the structural cavities. For PTFE applied as characterized, a pressure of at least 140 N / cm2must be applied in mechanical locking processes.

[0047] This process must be performed for at least 2 minutes.

[0048] Not being limited thereto, quartz glass can be used to enable these pressing processes to be performed. The reason for preferring this material is that it is a material that makes it possible to achieve the targeted surface roughness. Also, the quartz glass having a surface roughness close to almost zero microns allows the mechanical locking process of the superhydrophobic surface to be performed successfully.

[0049] Removal of PTFE nano-sized particles on the metal surface that are incapable of settling in the cavity structures after the pressing process

[0050] At least one scraper is used to perform these processes. Preferably a scraper with a speed value of 0.5 cm / second is used to perform this process. With this process, excess PTFE on the metal surface can be removed.

[0051] This process step can also be applied after mechanical locking if preferred.

[0052] Performing the sintering process The sintering process is performed to form bonds between PTFE and the metal surface.

[0053] The temperature of this sintering process is at a value in the range of 250 > to 350 °C.

[0054] The duration of the sintering process is at a value between 1 to 30 minutes.

[0055] As a result of the process steps applied as characterized, it is possible to position PTFE in the cavities created on metal surfaces. As mentioned, PTFE, which has technical solutions and advantages, is capable of providing metal surfaces superhydrophobic properties at first. In addition, it is possible to provide a coating that provides thermal and load resistance for metal surfaces.

[0056] With the characterized process steps mentioned in the invention, it is possible to obtain a metal surface provided with superhydrophobic properties without using a material with carcinogenic technical disadvantage.

[0057] The process steps applied are relatively easy and low-cost compared to the process steps of the method in the present technique.

[0058] The method with such technical application can be applied to the surfaces of various metals commonly used in the technique.

[0059] Metals with superhydrophobic surfaces obtained in the invention can be used to provide different functions in many technical fields according to the type of metal. The main object here is that the material used to provide superhydrophobic properties for the relevant technical field is not carcinogenic, is not costly and has high mechanical and thermal properties. In addition, it is to introduce a method that can be applied to metals that are frequently used in the technique that is not easily applicable and costly. Also, the relevant technique is also applicable to metals with a large surface area.

[0060] The scope of protection of the invention is specified in the appended claims and cannot be limited to what is described for illustrative purposes in this detailed description. It is clear that a person skilled in the technique can produce similar embodiments in the light of what is explained above, without deviating from the main theme of the invention.

Claims

CLAIMS1. A method for providing superhydrophobic properties to at least one surface of metals, characterized by the application of the following process steps which enable the application of a non-carcinogenic material having mechanical and thermal resistance to at least one surface of metals;- performing pre-treatments on the metal surface wherein cavities are formed on the metal surface for the next process steps, wherein cleaning processes are performed with at least one chemical solution,- preparing the solution providing the superhydrophobic properties, wherein the solution contains PTFE as an active ingredient and at least one solvent,- filling the prepared solution into an air-blast atomizer and applying it to the surface of the metal, wherein said spraying method is performed at a value in the range of 1 to 5 bar removing at least one solvent from the medium in this process step performing pressing process for mechanical locking of PTFE in cavities on metal surfaces wherein said pressing process here is performed with a pressure application of at least 140 N / cm2removing excess PTFE incapable of settling in the cavities remaining on the surface of the metalperforming sintering processes.

2. A method according to Claim 1 , characterized in that isopropanol is present in the solution as solvent.

3. A method according to one of the preceding claims, characterized in that the amount of PTFE is at a value between 0.5 / 10 mg / ml to 1.5 / 10 mg / ml for PTFE / isopropanoL4. A method according to one of the preceding claims, characterized in that the solution used in the cleaning process comprises at least one of acetone, isopropanol and / or an alcohol-based compound.

5. A method according to one of the preceding claims, characterized in that the distance of the nozzle used in the air-blast atomizer method to the metal surface is a value between 20 to 50 cm.

6. A method according to one of the preceding claims, characterized in that the particle size of PTFE is a value in the range of 100 to 500 nm.

7. A method according to one of the preceding claims, characterized in that quartz glass material is used in pressing processes.

8. A method according to one of the preceding claims, characterized in that the pressing process is performed for at least 2 minutes.

9. A method according to one of the preceding claims, characterized in that said excess PTFE is removed by a scraper having a speed of 0.5 cm / second.

10. A method according to one of the preceding claims, characterized in that said sintering process has a temperature value in the range of 250 > to 350 □.11 . A method according to one of the preceding claims, characterized in that the duration of said sintering process is a value in the range of 1 to 30 minutes.