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Engineers consider various parameters while designing new systems and machines. Creating ideal conditions for the designed system to work optimally is about analyzing the risks that pose a threat to the said system.
Material strength, surface hardness, thermal resilience, and corrosion resistance are the few most commonly considered design factors, along with economic efficiency. Engineers eliminate risks by taking preventative measures during the design phase.
Contact with water is one of the conditions which can be threatening to certain materials and systems. There are multiple solutions to eliminate the risk of contact with water, but in this article, we will focus on hydrophobic coatings.
What is a hydrophobic material
A hydrophobic material is a material that displays the tendency to repel water. In simpler terms, hydrophobic is a technical term used for materials “afraid” of water, as the Latin word “phobia” suggests.
In some applications, this “fear” of water is advantageous to prevent undesired conditions.
What is Hydrophobic Coating?
Hydrophobic coating is the process of layering the surface of a non-hydrophobic material with a water repellent to infuse the base material with hydrophobic properties.
Materials such as; manganese oxide polystyrene, zinc oxide polystyrene, precipitated calcium carbonate, carbon nano-tube structures, silica nano-coating, and fluorinated silanes are the most commonly used coating materials.
How do hydrophobic materials work?
All fluids tend to minimize their surface area. This tendency to maintain a minimalist surface area is achieved by the attraction between the fluid molecules. The attraction generated by the molecules to minimize the surface area is called surface tension. Yet, fluid molecules don’t just get attached to other fluid molecules, they can also interact with other phases.
A non-hydrophobic material forms a stronger attraction to the fluid molecule than the bond within the fluid itself. The more powerful bond which is formed between the material and the fluid breaks the surface tension and allows the fluid to be spread over the non-hydrophobic material.
On the other hand, the strength of the bond formed between the material and the fluid is not strong enough to break the surface tension, therefore, the fluid remains together.
Coating Methods for hydrophobic materials
The application method of the coating depends on the primary element in the coating material.
The silica-based material is the easiest to apply. Silica-based materials are in the form of gel which allows application by dipping or spraying. The downside of silica-based coating is the durability since there isn’t a strong bond between the coater and the material.
The oxide polystyrene-based coaters are much more durable when compared to silica-based coaters however, the application of polystyrene-based material is quite costly. Oxide polystyrene-based coaters are applied by electro-disposition or chemical etching.
Carbon nano-tubes are excellent in hydrophobic properties, but they are challenging and expensive to synthesize with today’s technology.
Uses
Hydrophobic coatings are used frequently in various industries. Its most common use is to protect structural elements from water corrosion.
Construction elements are some of the most commonly coated materials. Load-bearing elements must be protected from corrosion caused by humidity. Hydrophobic coating can be seen on steel structures of elevator shafts, steel construction beams, and other metal elements of the construction industry.
Another industry that utilizes hydrophobic coatings is the maritime industry. The corrosive nature of saltwater can be destructive to metals even if they are coated with paint or other surface coating methods. Hydrophobic coatings are extremely efficient in protecting against corrosion since they severe the contact between the corrosive and the base material.
Hydrophobic coatings perform extremely well as isolation material. Machine parts, structural elements, and various gaps that need to be watertight can be coated with hydrophobic agents to ensure isolation against water.
The self-cleaning properties of hydrophobic materials are another benefit that’s commonly utilized. Surface panels that are used for pre-fabricated or steel construction projects can be covered with hydrophobic materials to help with water isolation and induce the outer covering layer with self-cleaning properties to protect visual aesthetics. Another area where the self-cleaning properties of hydrophobic coatings come in handy is paint coatings for vehicles. The good price-performance ratio and ease of application of silica-based coatings make them commercially available.
New advances in technology provide engineers with innovative solutions to protect against water and its negative effects. Hydrophobic coatings are a novel, efficient, and long-lasting protective layer for systems that are not supposed to be in contact with water. Various industries such as maritime and construction utilize the power of hydrophobic coatings regularly. Efficiency and the longevity of the result are highly dependent on the material and the method of application. We believe that the information curated in this article will prove as a useful guideline for hydrophobic coatings.
