Engineering topics

Farmer, Serene

Publications and source records attributed to Farmer, Serene.

6 records

NASA NTRS2017

Generation of High Pressure Oxygen via Electrochemical Pumping in a Multi-Stage Electrolysis Stack

An oxygen pump can produce high-purity high-pressure oxygen. Oxygen ions (O(2-)) are electrochemically pumped through a multi-stage electrolysis stack of cells. Each cell includes an oxygen-ion conducting solid-state electrolyte between cathode and anode sides. Oxygen dissociates into the ions at the cathode side. The ions migrate across the electrolyte and recombine at the anode side. An insulator is between adjacent cells to electrically isolate each individual cell. Each cell receives a similar volt potential. Recombined oxygen from a previous stage can diffuse through the insulator to reach the cathode side of the next stage. Each successive stage similarly incrementally pressurizes the oxygen to produce a final elevated pressure.

Setlock, John A↗

NASA NTRS2017

Environmental Stability and Oxidation Behavior of HfO2-Si and YbGd(O) Based Environmental Barrier Coating Systems for SiCSiC Ceramic Matrix Composites

Ceramic environmental barrier coatings (EBC) and SiCSiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft propulsion systems because of their ability to significantly increase engine operating temperatures, improve component durability, reduce engine weight and cooling requirements. Advanced EBC systems for SiCSiC CMC turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant material development challenges for the high temperature CMC components is to develop prime-reliant, environmental durable environmental barrier coating systems. In this paper, the durability and performance of advanced Electron Beam-Physical Vapor Deposition (EB-PVD) NASA HfO2-Si and YbGdSi(O) EBC bond coat top coat systems for SiCSiC CMC have been summarized. The high temperature thermomechanical creep, fatigue and oxidation resistance have been investigated in the laboratory simulated high-heat-flux environmental test conditions. The advanced NASA EBC systems showed promise to achieve 1500C temperature capability, helping enable next generation turbine engines with significantly improved engine component temperature capability and durability.

Ceramic Matrix Composites↗

NASA NTRS2016

Generation of High Pressure Oxygen via Electrochemical Pumping in a Multi-stage Electrolysis Stack

An oxygen pump can produce high-purity high-pressure oxygen. Oxygen ions (O.sup.2-) are electrochemically pumped through a multi-stage electrolysis stack of cells. Each cell includes an oxygen-ion conducting solid-state electrolyte between cathode and anode sides. Oxygen dissociates into the ions at the cathode side. The ions migrate across the electrolyte and recombine at the anode side. An insulator is between adjacent cells to electrically isolate each individual cell. Each cell receives a similar volt potential. Recombined oxygen from a previous stage can diffuse through the insulator to reach the cathode side of the next stage. Each successive stage similarly incrementally pressurizes the oxygen to produce a final elevated pressure.

Setlock, John A↗

NASA NTRS2006

Fuel Cell Research and Development for Future NASA Missions

NASA has been using fuel cell systems since the early days of space flight. Polymer Exchange Membrane Fuel cells provided the primary power for the Gemini and Apollo missions and more recently, alkaline fuel cells serve as the primary power source for the Space Shuttle. NASA's current investments in fuel cell technology support both Exploration and Aeronautics programs. This presentation provides an overview of NASA's fuel cell development programs.

Manzo, Michelle A.↗

NASA NTRS2001

Crystallographic Texture and Orientation Variants in Al2O3-Y3Al5O12 Directionally Solidified Eutectic Crystals

Eutectic rods of Al2O3 and Y3Al5O12 were grown by a laser-heated float zone method, and their microstructure and crystallographic texture were studied by scanning electron microscopy, electron backscattered diffraction and x-ray diffraction. The composites were found to be highly textured with two twin-related crystallographic orientation relationships between the phases. Electron backscattered diffraction was employed to determine the spatial distribution of the orientational variants within the samples and to define the crystallographic orientation of various microstructural features.

Frazer, Colleen S.↗

NASA NTRS1997

High Temperature Oxidation of Boron Nitride: Monolithic Boron Nitride - Part 1

High temperature oxidation of monolithic boron nitride (BN) is examined. Hot pressed BN and both low and high density CVD BN were studied. It is shown that oxidation rates are quite sensitive to microstructural factors such as orientation, porosity, and degree of crystallinity. In addition small amounts of water vapor lead to volatilization of the B2O3 oxide as H(x)B(y)O(z). For these reasons, very different oxidation kinetics were observed for each type of BN.

Jacobson, Nathan↗