Industrial Coating Types: Their Properties, Process, and Benefit

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  July 12, 2024

Understanding the different types of industrial coatings can shape an engineer’s or designer’s approach to part application. Hence, part manufacturers must have conscious knowledge of these different types of coatings and invest in their use.

Coating processes occur at the end of production, each suitable for different materials and applications. To ensure a quality final part, this article will introduce the meaning of industrial coating, the different types, and how to choose the right one.

Contents
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I
What are Industrial Coatings?

II
Types of Industrial Coatings

III
What are Things to Consider When Choosing Industrial Coatings?

IV
Conclusion

V
FAQs

What are Industrial Coatings?

Industrial coatings are a layer of special materials applied to a part’s surface to protect, decorate, and improve/add functionality. The most common function of industrial surface coating is protecting the final part from abrasion, corrosion, or UV radiation.

These types of industrial coatings are important post-finishing in the manufacturing, construction, automotive, aerospace, and marine industries.

Types of Industrial Coatings

Many industrial coating processes find use in the part manufacturing sector. This section will introduce the common ones, processes, compatible materials, benefits and limitations.

Epoxy Coating

Epoxy coating is the application of an epoxy layer created by a resin and a hardener to a part. The final part has better mechanical properties and chemical resistance. Epoxy coating is common in industrial, commercial, and residential settings.

Materials Supported by Epoxy Coating

Epoxy is compatible with metal, plastic, wood, brick, ceramics, and concrete. However, the coating does not adhere to silicone, vinyl, rubber, parchment, and wax.

Properties of Epoxy Coating

• High Durability: Epoxy-coated parts have better durability due to enhanced hardness and abrasion resistance.
• Chemical Resistance: The epoxy coating is excellently resistant to chemicals, including acids, alkalis, solvents, and petroleum products.
• Thermal Stability: These coated parts have high thermal stability with a maximum service temperature of 71°C to 300°C that allows them to function without degrading.
• High Corrosion Resistance: Epoxy coatings are impervious to moisture, which is a culprit for corrosion.
• Aesthetic Versatility: The coating process comes in several colors and finishes tailored to several visual appeals.

How Does Epoxy Coating Work?

After surface preparation, which involves cleaning the substrate to remove contaminants like dust, oil, and grease, mix the resin and the hardener according to the manufacturer’s instructions. Apply the mixture on the part surface using a brush or and cure the epoxy-coated part to harden the coating.

Applications of Epoxy Coating

• Automotive chassis coatings, engine component coatings;
• Marine ship hulls, boat decks;
• Aircraft wings, fuselage sections;
• Circuit board coatings, electronic component insulation;
• Interior and exterior of oil pipelines, and storage tanks.

Benefits of Epoxy Coating

• Long-lasting protection against wear, impact, and abrasion;
• Superior resistance to many chemicals;
• Available in various colors and finishes;
• Compatible with metal, concrete, plastic, and wood.

Limitations of Epoxy Coating

• Requires careful surface preparation, which increases production costs and time;
• Susceptible to UV rays, which can cause degradation;
• Produce toxic fumes;
• The coating is not flexible, so if the part cracks, it can affect the coating.

Polyurethane Coating

Polyurethane coatings form after reacting a polyol or a polyamine and an isocyanate with firm, durable, flexible, chemical resistant, and abrasion resistant surface coating. Their flexibility ensures they expand to match the substrate’s expansion. However, they do not absorb impacts, restricting their use to the automotive, flooring, and marine sectors.

Materials Supported by Polyurethanes Coating

Polyurethane is quick-drying and is compatible with use on wood, metal, or painted surfaces.

Properties of Polyurethane Coating

• High Durability: Polyurethane coatings offer exceptional durability due to their firmness, flexibility, abrasion, and chemical resistance.
• Flexibility: The coating can expand and contract alongside the substrate without cracking or peeling.
• Chemical Resistance: Polyurethane coatings highly resist chemicals like acids, alkalis, solvents, and oils.
• UV Resistance: Unlike epoxy coatings, polyurethane coatings do not degrade on exposure to UV light.
• Aesthetic Appeal: The coating finishes come in several colors and finishes.

How Does Polyurethane Coating Work?

Polyurethane coating involves cleaning the part surface and applying a primer to improve its adhesion. Mixing the two components (a polyol or polyamine and an isocyanate), applying the polyurethane mixture to the part using a brush, roller, or spray equipment, and curing will create a polyurethane-coated part.

Applications of Polyurethane Coating

• Aerospace: Provide insulation for the craft and its passengers, window panes, and exterior light coverings;
• Automotive: Seat cushions, bumpers, doors, and spoilers;
• Construction: Flooring, steel and concrete supports, finished architectural features;
• Military: Sealing and exterior protection for aircraft, naval vessels, and personal protective equipment for soldiers.

Benefits of Polyurethane Coating

• Long-lasting protection against wear, impact, and environmental factors;
• It can expand and contract alongside the substrate to prevent cracking and peeling;
• Excellent chemical and UV resistance;
• Available in numerous colors and finishes.

Limitations of Polyurethane Coating

• The surface layer yellows with time;
• No impact absorption.

Polysiloxane Coating

Polysiloxane coatings are advanced protective coatings composed of silicon-oxygen bonds, which are immensely responsible for their exceptional durability, UV stability, and flexibility. It is a strong, waterproof polymer made of polymers that form successive layers of tight films, making it highly resistant to environmental factors.

Materials Supported by Polysiloxane Coating

Polysiloxane coatings are compatible with steel, aluminum, galvanized metal, concrete, plastics, glass, wood, ceramics, and composite materials.

Properties of Polysiloxane Coating

• Durability: Polysiloxane coatings offer long-lasting protection against physical damage and environmental wear.
• UV Resistance: The coating process is resistant to UV radiation.
  Flexibility: Like polyurethane coating, it expands to mimic the substrate movements without cracking or peeling.
• Chemical Resistance: The coating resists chemicals like solvents, acids, and alkalis.
• Thermal stability: The coating process can function in high temperatures, about 300 °C without degrading.

How Does Polysiloxane Coating Work?

Clean the part and apply a primer to improve the part’s adhesion. Afterward, mix the base and curing agent according to the manufacturer’s instructions and apply the mixed Polysiloxane coating using brushes, rollers, or spray equipment. Cure the just-coated surface for a specified period.

Applications of Polysiloxane Coating

• Marine ship hulls;
• Protecting offshore platforms and pipelines in the oil and gas industry;
• Coating bridges and overpasses;
• Automotive Body panels;
• Wind turbine blades;
• Storage tanks and chemical processing equipment.

Benefits of Polysiloxane Coating

• Long-lasting protection against physical and environmental damage;
• They perform well in harsh conditions, including UV radiation, moisture, and chemical exposure;
• They are flexible;
• Stability across a wide temperature range;
• Many formulations are environmentally friendly with low VOC emissions.

Limitations of Polysiloxane Coatings

• It can become brittle;
• Typically more expensive than polyurethanes.

Zinc-Rich Coating

A zinc-rich coating is a layer of zinc particles deposited on a part that provides a substrate with good corrosion resistance and aesthetic value. The zinc layer is a sacrificial material that works because it is more reactive than the substrate. As a result, it absorbs the oxygen molecule that would corrode the substrate even when scratched.

Materials Supported by Zinc Coating

Zinc coating is compatible with metals like steel, iron, and aluminum and is primarily used to protect them from corrosion.

Properties of Zinc Coating

• Durability: Zinc coatings offer long-lasting protection against corrosion and physical damage.
• Corrosion Resistance: Zinc acts as a sacrificial anode, corroding in place of the base metal.
• Adhesion: Provides excellent adhesion to a variety of base metals.
• Conductivity: It maintains good electrical conductivity.
• Thermal Stability: Zinc coated can withstand temperatures up to about 200°C without significant degradation.

How Does Zinc Coating Work?

Clean the surface to remove contaminants and pretreat the surface with pickling, degreasing, or abrasive blasting to enhance adhesion. Afterward, use hot-dip galvanizing, electroplating, or spraying to coat the surface with zinc. Allow the zinc-coated part to cool, and inspect for uniformity and coverage.

Applications of Zinc Coatings

• Ship hulls and marine equipment;
• Bridges, overpasses, and structural steel;
• Automotive body panels and undercarriages;
• Transmission towers and wind turbine components.

Benefits of Zinc Coatings

• Provides durable protection against corrosion;
• Effective in various harsh conditions, including moisture and chemical exposure;
• Often more economical than other protective coatings, e.g., epoxy coating;
• Application methods are well-established and straightforward.

Limitations of Zinc Coatings

• Less effective at very high temperatures above 200 °C;
• It requires periodic maintenance and touch-ups in aggressive environments;
• It can develop a dull appearance over time.

Ceramic Coating

Ceramic coating is a permanent or semi-permanent solution that involves applying a polymer solution to a part’s surface. The coating blends with the surface and creates a hydrophobic layer of protection.

It is common in the automotive industry, especially in painting. The chemical bonding and creation of a new layer leave the car’s factory paint job untouched.

Materials Supported by Ceramic Coating

Ceramic coating is compatible with various materials, including metals (steel, aluminum, titanium), plastics, glass, composites, etc.

Properties of Ceramic Coating

• Ceramic-coated parts can withstand high temperatures, often exceeding 1000°C;
• The coating is resistant to chemicals like solvents, acids, and alkalis;
• Ceramic coatings provide a hard, protective layer that resists scratches and abrasions;
• They protect materials from oxidation and corrosion.

How Does Ceramic Coating Work?

Ceramic coatings are applied through thermal spraying, which involves using high-temperature plasma or flame to melt ceramic powders, spraying the molten ceramic onto the substrate, and allowing it to cool. Other methods include dip and spin coating, which involves immersing or spinning the substrate in a ceramic slurry. Afterwards, the part is dried and sintered.

Applications of Ceramic Coating

• Protecting machinery and tools from wear and high temperatures;
• Coating of gas turbines and boilers;
• Insulating electronic components and circuit boards;
• Coating medical implants and devices;
• Food processing equipment and containers;

Benefits of Ceramic Coating

• Effective in extremely high-temperature conditions;
• Resistant to various chemicals, enhancing durability;
• Offers a hard, scratch-resistant surface;
• Protects materials from oxidation and corrosion;
• Reduces friction, improving efficiency in moving parts.

Limitations of Ceramic Coating

• It is more expensive than other types of coatings;
• Requires specialized equipment and expertise for proper application;
• It can be brittle and may crack under certain conditions;
• Requires thorough surface preparation for optimal adhesion;
• It often requires a thicker application, which may only be suitable for some applications.

Metallic Coating

Similar to zinc coating, metallic coatings involve protecting a part with a layer of metallic particles such as aluminum, nickel, chromium, etc. Each metallic particle has unique functions. For example, chromium coating can protect parts from corrosion, while aluminum improves corrosion resistance and aesthetics.

Materials Supported by Metallic Coating

Metallic coatings are compatible with various metals including steel, aluminum, and titanium.

Properties of Metallic Coating

• Corrosion Resistance: They protect underlying materials from oxidation and chemical damage.
• Adhesion Strength: High-quality metallic coatings bond strongly with the substrate, ensuring durability.
• Electrical Conductivity: Metallic coatings often improve electrical conductivity for electronic components.
• Hardness: It provides increased surface hardness, improving wear resistance.
• Ductility: Some metallic coatings maintain flexibility, preventing cracks during deformation.

How Does Metallic Coating Work?

After cleaning the part surface to remove contaminants that can reduce the final part’s quality, apply the metallic coating by thermal spraying or electroplating. Thermal spraying involves melting the metal powders, spraying the molten metal onto the substrate, and allowing it to cool.

On the other hand, electroplating involves immersing the substrate in a solution containing metal ions. When an electric current passes through the solution, metal ions are deposited on the substrate.

Applications of Metallic Coating

• Coated gas turbines and boilers in the power generation industry;
• Coating medical implants and devices for improved biocompatibility and corrosion resistance.

Benefits of Metallic Coating

• Excellent corrosion resistance;
• Long service life;
• Improved reflectivity.

Limitations of Metallic Coating

• The coating won’t work with all surface types;
• It requires huge maintenance, which can increase production costs;
• It does not offer much protection from water spots.

What are Things to Consider When Choosing Industrial Coatings?

Selecting the ideal industrial coating depends on understanding the coating process and some factors that can affect its Use. This section will introduce several factors that can aid in selecting the best coating process for your project.

Substrate Type

Every coating process highlighted above has a specific substrate it is compatible with. For example, metallic coatings are majorly compatible with metals, while epoxy is compatible with metals, wood, and concrete.

The substrate’s need can also affect the choice of coating. Polyurethane coating is a common method for anti-corrosive properties with UV protection for metals, wood, and plastic.

Environmental Conditions

The environment of use can also determine the coating process. Consider weather, temperature, UV, and chemicals. Choose a coating technique that will provide the necessary attributes.

For example, polysiloxane coating is a better option than epoxy coating when looking for a corrosion and UV-resistant part.

Applications

Practical considerations such as ease of application, drying time, and curing conditions can also determine the surface coating technique.

Epoxy, polyurethane, and polysiloxane coatings differ from zinc plating based on the application process. The three require mixing the bases and using rollers, sprays, or brushes. Zinc coating, however, goes a step further by allowing hot dip galvanizing.

Performance Requirements

The performance of the part will require a unique degree of resistance to corrosion, abrasion, impact, etc. This, in turn, will determine the ideal coating process for your project. When you are looking for a part with UV resistance, epoxy coating is not the best option compared to polysiloxane and polyurethane. You should choose a method that ensures you meet your performance goals.

Cost Considerations

The cost of the indented process will shape your choice. However, choose a process that concerns performance while not breaking the bank. For example, zinc coating is a cheaper process than epoxy coating.

Regulatory Compliance

The regulation associated with using the part can also determine your coating processes. As a result, you should ensure you comply with the standards governing industrial coatings and opt for coatings techniques that meet industry-specific certifications and standards.

Conclusion

Coating can improve the part’s structure, function, and application. Understanding its uniqueness as a post-production process is important. This article introduced the different types of coating and how to choose the right one.

FAQs

Is Coating Worth it?

Yes, the coating is worth it because it enhances appearance and functionality. Benefits of coatings include improved corrosion resistance, durability, and shielding against environmental conditions.

What is the Difference Between Coating and Painting?

The most simple way to differentiate between coating and paint is that paint is a type of coating, but not all coatings are paints. Painting is a thin and running substance used to add color. On the other hand, coatings are to protect and are optimized for adhesion.

What is the Coating for Galvanized Steel?

The common type of coating for galvanized steel is zinc coating using galvanization. It is highly corrosion resistant because the zinc coat provides barriers against corrosion and improves the mechanical properties of the galvanized steel.