What are thermal barrier coating products, and why are they essential for many needs?

At ThermaCote, we’re proud to offer a huge range of thermal barrier coating for spray foam and related outer coating needs. Here’s a breakdown of how thermal barrier coatings work, the types of outer coatings we offer, and some important additional information on these high-value products.

Thermal Barrier Coating Basics

For those just learning about thermal barrier coatings, here are the basics: These coatings are designed to provide an extra layer of protection against heat transfer. They can be applied to a variety of surfaces, including thermal barrier coating for spray foam insulation, metal roofs, and walls.

These coatings serve several direct purposes:

  • Protection from fire risks: Thermal barrier coatings have excellent fire resistance properties and can significantly reduce the risk of a fire spreading.
  • Allowing for higher operating temperatures: By creating a barrier between the surface and heat source, thermal barrier coatings allow for higher operating temperatures without damaging the underlying materials.
  • Insulation: Thermal barrier coatings can act as insulation, helping to keep heat in or out depending on the desired effect.
  • Substrate protection: Thermal barrier coatings can protect the underlying substrate from damage caused by extreme temperatures, corrosion, and wear.
  • Extending material life: By protecting against heat and other damaging elements, thermal barrier coatings can help extend the life of materials and components.

With these benefits in mind, thermal barrier coatings are often used in applications like building envelopes, roofing and various metal structure needs.

How Thermal Barrier Coatings Work

Here are the basic components that allow thermal barrier coatings to work as intended:

  • Thermal insulation mechanism: Ceramic topcoats are applied, creating a thermal gradient that reduces heat transfer.
  • Layered structure: Effective thermal barrier coatings need to have the right structuring to be effective. This can include elements like the metal substrate, bond coat, thermally-grown oxide and a ceramic topcoat.
  • Failure modes: Thermal barrier coating failure mechanisms, such as thermal shock, sintering and TGO-related cracking, are quite complex and are still being fully understood.

Types of Thermal Barrier Coatings

There are two main varieties of thermal barrier coatings to consider:

Ceramic-Based Coatings

Several specific sub-categories comprise ceramic-based coatings:

  • ThermaCote: Our proprietary coating involves hollow ceramic microspheres in a binder. These can be spray-applied to steel, aluminum and cast iron, and are available in several colors.
  • YSZ (Yttria-Stabilized Zirconia): Often preferred for low thermal conductivity and thermal cycling resistance.
  • Gadolinium Zirconate: Used for high stability and insulation at high temperatures.
  • Lanthanum Zirconate: This coating has strong thermal stability, making it common in gas turbine engines and similar uses.
  • Yttria-Calcia-Zirconia: Similar to YSZ, but with enhanced performance qualities.
  • Magnesium Zirconate: Due to its strong insulation characteristics, this coating is often used in aerospace settings.
  • Hafnium Oxide: This coating has a high melting point and excellent thermal stability.
  • Aluminum Oxide: Also referred to simply as Alumina, this coating is used to improve oxidation resistance in many settings.
  • Rare-earth or specialized coatings: Several other rare-earth or specialized ceramic coatings also exist, including rare-earth zirconate and ceria combinations.

Metallic-Based Coating

The primary coating found here is platinum-based, which offers exceptional oxidation resistance and is ideal for high-temperature industrial and aerospace applications.

Common Applications of Thermal Barrier Outer Coatings

Thermal barrier coatings have several common and popular applications due to their impressive qualities:

Building Envelopes & Roofing

Many buildings can reap the benefits of a thermal barrier coating applied to their exterior walls and roofing. These coatings can help reduce heat transfer, improve energy efficiency, and prevent weathering and corrosion due to environmental elements. They help seal and insulate interior walls while also reducing cooling loads.

Metal Roofs

Metal roofing is often used in industrial and commercial buildings due to its durability and cost-effectiveness. However, metal roofs can be prone to heating up quickly, making the interior of the building uncomfortable and leading to higher energy costs. A thermal barrier coating can help reduce heat transfer, keeping the building cooler and more comfortable for occupants while also reducing HVAC consumption.

Industrial Gas & Turbines

There are several aeronautical and power-generation uses of thermal barrier coatings, including for thermal cycling protection. These coatings are often applied to gas turbine engines used in aircraft and power plants, as they can withstand extremely high temperatures and protect the underlying materials from thermal fatigue.

Automotive & Exhaust Management

Thermal barrier coatings are often applied to vehicle exhaust systems to manage their thermal loads while improving performance and reducing emissions. These coatings can reduce the heat transferred to other components under the hood, increasing their lifespan and efficiency.

Application Techniques

Here are some basics on thermal barrier coating application:

Surface Prep & Equipment

Surface preparation and proper equipment use are important for any outer coating. Standard painting prep can often be used here. In addition, airless sprayers tend to be effective for surface prep during large-scale operations.

Application Methods

Several different spraying methods, including APS, EBPVD, HVOF, ESAVD and others can be used. Emerging new processes like solution-precursor plasma spray are also gaining popularity.

Performance Considerations

Here are some key areas to consider when selecting thermal barrier coatings:

  • Material selection: When it comes to material, there can be some trade-offs in terms of thermal conductivity, durability, thermal expansion and cost. Be sure to choose a material that best suits your specific application needs.
  • Durability and maintenance: Because of risks like sintering, shock, TGO damage and more, it’s important to consider the durability and maintenance requirements of your chosen thermal barrier coating. For example, ceramic coatings tend to be more brittle than metallic coatings and may require more frequent inspections and repairs.
  • Climate and emissivity: For many applications of thermal barrier coatings, such as cooling roofs or reflective coatings, the climate and emissivity of the coating are important factors to consider. For example, a highly reflective coating may be ideal for a hot and sunny climate, while a more heat-absorbing coating may be better suited for a colder environment.

Examples of Thermal Barrier Coatings in Use

Here are a couple examples of thermal barrier coatings and their active uses:

  • ThermaCote for roofing: Our ThermaCote products are regularly used in roofing to provide a waterproof, thermal barrier coating that reduces heat absorption and lowers cooling costs. This type of coating is ideal for hot climates where air conditioning costs can be significant.
  • Industrial gas turbines: YSZ or other rare-earth zirconates are often used to support high-temperature tolerance applications.

Challenges and Future Trends

As we look to the future in thermal barrier coatings, here are some concepts to keep an eye on:

  • Material limitations and phase instability: Certain materials used for these coatings have limitations. For instance, phase instability can take place at extreme temperatures for some materials, such as YSZ above 1200 degrees Celsius. Be sure to select materials that can withstand the necessary temperature range for your specific application.
  • R&D directions: As new ceramics like rare-earth zirconates become more common, research and development are ongoing for improved thermal barrier coatings.
  • Environmental focus: These coatings can play a huge role in green building credentials, LEED, urban heat island mitigation and more.

As you can see, thermal barrier coatings are immensely valuable for everything from substrate protection and product longevity to energy savings. At ThermaCote, we’re proud to offer a huge range of thermal barrier coatings and other outer coatings. Contact us today to consult with our experts on custom solutions!