Research Initiatives

Materials Passivation and Degradation in Low Earth Orbit

Air Force Office of Scientific Research, Multi-university research initiative (MURI-AFOSR)

As the Air and Space Forces evolve in the 21st century, the need for increased numbers of spacecraft with continually improving capabilities and durability, including manned vehicles and satellites, becomes imperative.

Our objective will be to elucidate the physical principles underpinning the main degradation mechanisms in the low Earth orbit (LEO) of materials envisioned for use in future spacecraft.

Primary damage of space vehicles in LEO results from collisions with hyperthermal atomic oxygen. These vehicles will also be subjected to irradiation with high-energy particles as well as solar radiation. We utilize a combination of unique facilities, synchrotron X-ray diffraction (XRD), surface science methods, and transmission electron microscopy (TEM) with the corresponding expertise to experimentally probe the major environmental degradation mechanisms in space environments for a variety of materials.

Our aim is to predict materials and surface degradation in the LEO environment through a unified experimental effort in which primary degradation mechanisms are investigated in situ.

This program is a multi-university research initiative between the University of Pittsburgh and University of Illinois at Urbana-Champaign.

Nanoscale Metal oxidation

National Science Foundation (NSF), Department of Energy (DOE)

Environmental stability is an essential property of most engineered materials. Furthermore, surface oxidation processes play critical roles in environmental stability, high-temperature corrosion, electrochemistry, catalytic reactions, gate oxides, and thin film growth, as well as fuel reactions.

As engineered materials approach the nanometer regime, control of their environmental stability at this scale will become crucial. Yet nearly all classical theories assume a uniform growing film, where structural changes are not considered because of the lack of previous experimental methods to visualize this nonuniform growth in conditions that allowed for highly controlled surfaces and impurities.

One can now see structural changes under controlled surface conditions, by in situ ultra-high vacuum transmission electron microscopy (UHV-TEM), and thereby challenge the commonly used assumption of a uniform oxide formation.

Our objective is to fundamentally understand these nanoscale oxidation processes by a coordinated theoretical and experimental (in situ UHV-TEM) effort, where the impact is potentially a new paradigm for oxidation.