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Commercial/military fixed-wing aircraft and rotorcraft engines often have to operate in significantly degraded environments consisting of sand, dust, ash, and other particulates. Marine gas turbine engines are subjected to salt spray, while the coal-burning industrial power generation turbines are subjected to fly ash. The presence of solid particles in the working fluid medium has an adverse effect on the durability of these engines as well as performance. Typical turbine blade damages include blade coating wear, sand glazing, calcia–magnesia–alumina–silicate (CMAS) attack, oxidation, and plugged cooling holes, all of which can cause rapid performance deterioration including loss of aircraft. This research represents the complex thermochemomechanical fluid structure interaction problem of semimolten particulate impingement and infiltration onto ceramic thermal barrier coatings (TBCs) into its canonical forms. The objective of this research work is to understand the underpinning interface science of interspersed graded ceramic/metal and ceramic/ceramic composites at the grain structure level for robust coatings and bulk material components for vehicle propulsion systems. This research enhances our understanding of the fundamental relationship between interface properties and the thermomechanical behavior in dissimilar materials for materials by design systems, and creates the ability to develop and fabricate materials with targeted macroscale properties as a function of their interfacial behavior. This project creates a framework to enable the engineered design of solid–solid and liquid–solid interfaces in dissimilar functionalized materials to establish a paradigm shift toward science from the traditional empiricism in engineering TBCs and high temperature highly loaded bulk materials. An integrated approach of modeling and simulation, characterization, fabrication, and validation to solve the fundamental questions of interface mechanisms which affect the properties of novel materials will be validated to guide component material solutions to visionary 2040+ military vehicle propulsion systems.

Gas turbine engines for military/commercial fixed-wing and rotary wing aircraft use thermal barrier coatings in the high-temperature sections of the engine for improved efficiency and power. The desire to further make improvements in gas turbine engine efficiency and high power-density is driving the research and development of thermal barrier coatings with the goal of improving their tolerance to fine foreign particulates that may be contained in the intake air. Both commercial and military aircraft engines often are required to operate over sandy regions such as in the middle-east nations, as well as over volcanic zones. For rotorcraft gas turbine engines, the sand ingestion is adverse during take-off, hovering near ground, and landing conditions. Although most of the rotorcraft gas turbine engines are fitted with inlet particle separators, they are not 100% efficient in filtering fine sand particles of size 75 microns or below. The presence of these fine solid particles in the working fluid medium has an adverse effect on the durability of turbine blade thermal barrier coatings and overall performance of the engine. Typical turbine blade damage includes blade coating wear, sand glazing, Calcia-Magnesia-Alumina-Silicate (CMAS) attack, oxidation, and plugged cooling holes, all of which can cause rapid performance deterioration including loss of aircraft. The objective of this research is to understand the fine particle interactions with typical turbine blade ceramic coatings at the microstructure level. Finite-element based microstructure modeling and analysis has been performed to investigate particle-surface interactions, and restitution characteristics. Experimentally, a set of tailored thermal barrier coatings and surface treatments were down-selected through hot burner rig tests and then applied to first stage nozzle vanes of the gas generator turbine of a typical rotorcraft gas turbine engine. Laser Doppler velocity measurements were performed during hot burner rig testing to determine sand particle incoming velocities and their rebound characteristics upon impact on coated material targets. Further, engine sand ingestion tests were carried out to test the CMAS tolerance of the coated nozzle vanes. The findings from this on-going collaborative research to develop the next-gen sand tolerant coatings for turbine blades are presented in this paper.

Modern gun barrel technology faces a number of challenges related to the use of chromeplated steel at the interior bore surface. The amount of allowable chrome has been significantly reduced due to environmental, health, and safety concerns. Furthermore, current munitions and propellants lead to erosion and condemnation of gun barrels well before their 10,000 round expected lifetime. This has precipitated a search for longer-lasting bore liners, such as refractory metals deposited by explosive bonding. The cost and difficulty associated with shaping these materials have made them impractical choices to date. Gas Dynamic Cold Spray consolidation of refractory metals and alloys was selected as an alternative to extrusion for additive manufacture of donor tubes. Tantalum-10 Tungsten alloy donor tubes have been produced by Cold Spray and tested for compatibility with the cladding process. A 1-meter (3-foot) long tube was produced to test scalability.

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