Thermal Barrier Coating Materials

Industrial and aerospace components operating in high-temperature environments face a fundamental challenge: the base materials they are made from have thermal limits. When operating temperatures approach or exceed those limits, components degrade, deform, or fail ahead of their intended service life. Thermal barrier coating materials address this by insulating the component substrate from heat, either enabling operation at higher temperatures than the base material could otherwise sustain, or extending service life by reducing the thermal load the substrate experiences during normal operation.

The two outcomes are distinct but related. In aerospace turbine applications, thermal barrier coatings enable engines to operate at higher temperatures, improving efficiency. In other contexts, the same materials serve primarily as protection, keeping a component within safe operating limits longer than an uncoated part would last.

How Thermal Barrier Coating Systems Are Structured

Thermal barrier coating systems are engineered in two layers, each serving a different function.

The first is a Metal/MCrAlY bond coat. This layer adheres to the substrate and protects against oxidation and corrosion. Without it, the interface between the substrate and the thermal barrier topcoat would be vulnerable to the oxygen and heat these systems are designed to manage. The bond coat is foundational to system performance and service life.

The second layer is the thermal barrier topcoat, the ceramic layer responsible for heat insulation. It limits the amount of thermal energy transferred to the substrate, allowing the component surface to experience temperatures the base metal beneath it could not tolerate directly.

These two layers work together as a system. Material selection, layer thickness, and application process all depend on the specific component, its substrate material, and the operating environment it will face. Multiple application processes are used across TBC systems, and the appropriate approach depends on the application's requirements.

Thermal Barrier Coating Materials and Their Properties

Within a two-layer TBC system, material selection at each layer is driven by the specific demands of the application. Key considerations include:

• Bond coat composition: Metal/MCrAlY alloys are selected for oxidation resistance at elevated temperatures and compatibility with both the substrate and the ceramic topcoat above them.
• Topcoat material: Ceramic topcoat materials provide the thermal insulation function. Selection depends on operating temperature range, thermal cycling requirements, and the balance between insulation performance and coating durability.
• System compatibility: The bond coat and topcoat must work together as a system. Material choices at one layer affect performance expectations at the other.

These variables interact in ways that make material selection an engineering decision rather than a straightforward specification. Linde AMT's portfolio of over 300 coating formulations supports this process across a wide range of application requirements.

Applications: Where Thermal Barrier Coating Materials Are Used

Thermal barrier coating materials are most closely associated with aerospace, where they are applied to turbine blades (buckets), vanes (nozzles), and combustion section components in jet engines. These components operate under some of the highest thermal loads in any engineered system, and thermal barrier coatings are a standard part of their design to perform and last.

Beyond aerospace, thermal barrier coatings are used in industrial gas turbines for power generation, where operating efficiency and component service life have direct economic consequences. In both contexts, the core value is the same: keeping components within safe operating limits longer, reducing maintenance downtime and the costs associated with premature part replacement.

Selecting the Right Thermal Barrier Coating Materials

Choosing thermal barrier coating materials is an engineering decision shaped by several interacting variables:

• Operating temperature range and the nature of thermal cycling the componentwill experience
• Substrate material and its compatibility with bond coat and topcoat chemistries
• Exposure to oxidation, corrosion, or other environmental factors alongside heat
• Required service life and the maintenance constraints of the application

To discuss thermal barrier coating material selection for your application, contact Linde AMT's engineering team.

Why Linde AMT?

Linde Advanced Material Technologies (Linde AMT) delivers advanced coating materials, application services, and equipment to customers across aerospace, power generation, and industrial markets. With more than 75 years of coating innovation and a team of 2,500 engineers, technologists, and experts operating across 35 locations in 12 countries, Linde AMT brings integrated capabilities to complex coating challenges.

Global Coating Services, Linde AMT's coating services division, supports customers from material selection through application, drawing on a portfolio of over 300 coating formulations and in-house powder manufacturing and R&D resources. The goal is to identify and apply the right coating solution for each application, whether that means extending component service life, enabling operation in more demanding environments, or transitioning away from materials that no longer meet regulatory or performance requirements.

Frequently Asked Questions

What is a two-layer thermal barrier coating system?

A two-layer TBC system consists of a Metal/MCrAlY bond coat and a ceramic thermal barrier topcoat. The bond coat protects against oxidation and corrosion at the substrate interface, while the topcoat provides heat-insulating properties. Both layers are selected and applied as an integrated system.

What industries use thermal barrier coating materials?

Thermal barrier coating materials are used primarily in aerospace and power generation. Common applications include turbine blades (buckets), vanes (nozzles),and combustion-section components in jet engines and industrial gas turbines, where component service life and operating efficiency are critical.

How are thermal barrier coatings applied?

Multiple application processes are used depending on the component, substrate material, and operating environment. The specific demands of the application determine the right process. Linde AMT uses a range of application methods across its thermal barrier coating systems.