Latest from Materials

Thiti Tangjitsangiem | Dreamstime
'Availability of new foundry sand is already becoming a challenge, along with the need of providing new solutions to waste management,” according to the director of a metallurgical research center.
Branimir Ritonja | Dreamstime
Automotive cast parts.
Seesea | Dreamstime
Fire photo
Jacek Sopotnicki | Dreamstime
With deoxidized base iron, carbon levels can be increased to 3.30% C and alloying can be completely or nearly eliminated at the same time.
The developer of the highpurity 4 mol yttriastabilized zirconia formulation also supplies a patented deposition process creating an effective way to seal turbine components surface against thermal distress oxidation corrosion and general wearandtear

Thermal Barrier Coatings To Improve Investment Cast Parts

April 24, 2013
Low thermal-conductivity formulation Emulsion Detonation Synthesis

Possibly the most dynamic metalcasting market niche is investment casting of turbine engine components — blades, blisks, and vanes — which has benefited not only from sustained demand from the aerospace and industrial gas engine market, but has advanced significantly on its own developments in materials science, product design, and process control. But even manufacturers soaring in that high-value atmosphere will find the need to lift their products’ performance.

Innovnano is a Portuguese developer and manufacturer of high-performance ceramic powder that has produced a coating material capable of withstanding extreme temperature variations. The high-purity 4YSZ (4 mol% yttria-stabilized zirconia) formulation has significance as a thermal barrier for aerospace turbine engine components. Due to its low thermal conductivity only a very thin application is needed for an effective thermal coating, thereby ensuring that the weight of individual components of the rotating turbines is kept to a minimum.

The developer is a subsidiary of Companhia União Fabril (CUF), an industrial chemical company, and a specialty manufacturer of high-quality nanostructured zirconia-based powders and aluminum-zinc-oxide sputter coating targets. With its new, modular production center, Innovnano noted it can scale-up production to 1,000 metric tons/year to meet the growing industrial-scale demand for high-performance materials.

In addition to dedicated zirconia-based ceramic powder production, Innovnano custom manufactures zirconia-based powder products to clients’ individual specifications.  Customized, sub-micron powders are available in stable aqueous or ethanol-based suspensions for an emerging suspension plasma spray application, as well as spray-dried granules, with or without binder for optimal handling.

High heat and hardness

With a melting point of ~2,700°C and hardness of 14 GPa, 4YSZ is described as “the ideal topcoat thermal barrier.” CPT, an independent R&D center for thermal spray technology at the University of Barcelona, has shown that 4YSZ exhibits the same thermal diffusivity and corrosion resistance as conventional coatings, but at a much lower thickness and weight. 

Innovnano’s patented method of coating deposition is called Emulsion Detonation Synthesis (EDS). It’s this process that ensures that 4YSZ is applied with a fine nanostructure and uniform dispersion of mixed oxide components.  These powder properties are vital to ensuring that the thermal barrier on the surface of the turbine parts remains resistant to micro-cracking and thermal shock, allowing it to expand with the metal substrate without breaking.

The developer noted these qualities make 4YSZ “ideal for ‘no-fail’ applications,” like aerospace engine operations. 

4YSZ thermal barrier coatings not only provide thermal protection to the alloy components, they also shield them from oxidation, corrosion, and the general effects of wear-and-tear. As a result, the coating will help to prolong the operating life of turbine engines.  Innovnano further claims its ceramic powder has advanced thermal-barrier coating properties that address the technological expectations of turbine manufacturers and operators, for performance efficiency. As such, the coating makes it possible to operate the turbines at increased temperatures but with minimal downtime or cost for maintenance. 

“There has been a dramatic growth in the market for high-performance materials within the aerospace community and other high-performance settings,” stated technical director Joâo Calado.  “Recognizing this, Innovnano has recently relocated to a purpose-built manufacturing facility with significantly increased production capacity, and with our advanced EDS technology we are able to provide the highest quality thermal barrier topcoat materials at the volumes that industry needs.”

About the Author

Robert Brooks | Content Director

Robert Brooks has been a business-to-business reporter, writer, editor, and columnist for more than 20 years, specializing in the primary metal and basic manufacturing industries. His work has covered a wide range of topics, including process technology, resource development, material selection, product design, workforce development, and industrial market strategies, among others. Currently, he specializes in subjects related to metal component and product design, development, and manufacturing — including castings, forgings, machined parts, and fabrications.

Brooks is a graduate of Kenyon College (B.A. English, Political Science) and Emory University (M.A. English.)