At first glance, it might seem that the aerospace industry, oil and gas production and semiconductor fabrication have little in common.

Figure 1. To safeguard everything from jet turbine engines to semiconductors from such conditions, manufacturers use what is known as an environmental barrier coating.Figure 1. To safeguard everything from jet turbine engines to semiconductors from such conditions, manufacturers use what is known as an environmental barrier coating.But components critical to all three sectors, among dozens of other industrial sectors, face constant and challenging exposure to extreme conditions. These conditions include high temperatures and extremely abrasive and corrosive environments. To safeguard everything from jet turbine engines to semiconductors from such conditions, manufacturers use what is known as a thermal or environmental barrier coating, or T/EBC.

T/EBC coatings utilize advanced material systems that can be sprayed on to metallic or composite surfaces. Once in place, the coatings form an integral part of a critical component’s exhaust heat management system and environmental protection shield.

Critical for design engineers, coatings allow equipment to operate at higher operating temperatures. For example, advanced thermal coatings can allow temperatures higher than the melting point of a metal airfoil in jet aircraft applications. This is an important consideration as demand increases for efficient engines that can operate at high temperatures while still delivering high durability and long lifetimes. Equally critical is the need to use lightweight coatings to minimize what is known as the parasitic mass that is added to a component.

To be most effective, a thermal barrier coating offers the following characteristics: a high melting point, no phase transformation between ambient temperature and operating temperature, low thermal conductivity, chemical inertness, thermal expansion similar to the component’s substrate, good adherence to the substrate, and a low sintering rate for a porous microstructure.

Performance requirements for the aerospace, oil and gas and semiconductor industries make clear the importance of partnering with an industry-leading coatings expert with a global reputation for delivering custom processing solutions across a range of platforms.

Saint-Gobain Coatings Solutions has applied its knowledge of materials technology to develop a complete line of industry-leading powders that extend the life and enhance the performance of parts and equipment in abrasive, corrosive and high-temperature applications.

These materials are engineered to provide optimal wear resistance as well as thermal and electrical insulation. Several technology platforms are employed to provide each material with the ideal properties.

  • Synthesis, including arc fusion, solid state sintering and chemical processes
  • Shaping, including size reduction, agglomeration, pressing and extrusion
  • Heat treating, including plasma fusion and sintering
  • Sizing, including classification, screening and homogenization

Coatings for the aerospace industry

The push for cleaner skies as well as efforts to control bottom-line issues related to fuel costs is leading aerospace manufacturers to seek more efficient turbine engines. As fuel combustion temperatures rise within the turbine, engine efficiencies increase and emissions of nitrogen oxides and carbon dioxide fall due to a more complete combustion of hydrocarbons. Developing materials that can operate under these extreme conditions has been the focus of aerospace R&D for many years.

In a commercial jet engine, fuel burns at up to 2,000 °C in the combustion chamber. The turbine, which extracts energy from the hot gases and provides the engine with power, is exposed to gases at temperatures between 850-1,700 °C. But the goal of improving engine efficiency means the temperature in the turbine inlet needs to climb even higher. The bottom line is that turbine blades need to be able to withstand long operating periods at temperatures that actually are above their melting point.

To protect turbine blades from this extreme heat, thermal barrier coatings (TBC) are applied. TBC systems consist of an insulating ceramic top coat applied over a metallic bond coat. A thermally grown oxide forms between the two layers.

Ceramics are chosen for the top coat because they exhibit both higher melting points than metal and low thermal conductivity. As the ceramic does not conduct the heat of the gas, the temperature of the blade alloy remains stable. This enables the turbine to run at higher temperatures and with higher efficiency.

The most commonly used ceramic is zirconia. In most cases, zirconium oxide (ZrO2) is partially stabilized with yttrium oxide (Y2O3). This combination offers a very good tradeoff between low thermal conductivity and mechanical toughness. New generation TBCs implement rare earth doping of the zirconia, leading to even lower thermal conductivity. The ceramic is applied in layers anywhere from 250-375 µm thick, and a complex alloy plating (i.e., the bond coat) is used to adhere it to the turbine blade alloy. This oxidation-resistant metallic bond coat also helps reduce heat transfer to the base material.

The thermal barrier coating both reduces the temperature of the blade alloy and protects against oxidation and hot corrosion from high-temperature gas. This means that turbine performance, life expectancy and efficiency are all significantly improved.

Coating solutions for multiple industries

Saint-Gobain Coating Solutions manufactures a wide range of technically superior thermal barrier coatings in the form of thermal spray powders and electron-beam physical vapor deposition (EB-PVD) ingots. Using its expertise in materials technology and process engineering, Saint-Gobain can deliver the best solution to protect equipment against high-temperature erosion, abrasion, oxidation and wear.

Most importantly, its products ensure longer service life and improved performance in extreme environments, such as those experienced by aircraft flying at 35,000 ft and oil and gas equipment operating thousands of feet below the Earth’s surface.

With its sophisticated process technology, Saint-Gobain can provide uniform chemistry and particle size control for completely homogenous powders. For each specific application, its team will tailor powder chemistry and particle size based on the demands of the equipment as well as the properties of the desired coatings.

This ability to tune the morphology, material homogeneity and purity to the customer’s needs results in maximum deposit efficiency and optimal coating performance.

Saint-Gobain Coating Solutions has three dedicated R&D facilities located in the United States, China and Europe, along with a lab for analyzing coating properties and performance.

In addition, the business has access to Saint-Gobain’s technical facilities, including 20 research centers and 101 development units, employing more than 3,500 scientists, engineers and technicians who are devoted to finding industry-leading, cutting edge solutions for our customers.

Partner with us to meet your next coating requirement.