Wright-Patterson Air Force Base

About: Wright-Patterson Air Force Base is a other organization based out in Wright-Patterson AFB, Ohio, United States. It is known for research contribution in the topics: Laser & Microstructure. The organization has 5817 authors who have published 9157 publications receiving 292559 citations. The organization is also known as: Wright-Patterson AFB & FFO.

Hole and Electron Extraction Layers Based on Graphene Oxide Derivatives for High‐Performance Bulk Heterojunction Solar Cells

Abstract: : Graphene, having a single-atom-thick sheet of carbon atoms packed in a 2D honeycomb lattices, possesses excellent electronic, thermal, and mechanical properties attractive for a large variety of potential applications, including transparent electrodes and/or active materials in electronic devices, solar cells, supercapacitors, batteries, fuel cells, actuators, and sensors. Graphene has also been found to be useful as the platform of biomedical sensors. The recent availability of solution processable graphene by exfoliation of graphite into graphene oxides (GOs), followed by solution reduction, has allowed the functionalization, characterization, and processing of graphene sheets via various solution methods. It has been demonstrated that GO consists of epoxy and hydroxyl groups on the basal plane and carboxylic groups at the edge. The C O bonds on the basal plane disrupt the conjugation of the hexagonal graphene lattice to render GO insulator or semiconductor. Due to strong interactions between the hexagonally sp 2 -bonded carbon layers in graphite, the solution oxidation of graphite requires strong oxidizing reagents (e.g., HNO 3 , KMnO 4 , and/ or H 2 SO 4 ) under harsh conditions. This often leads to severe damage to the carbon basal plane, and hence a poorly defi ned electronic structure. It remains a big challenge to design GO-based materials with controlled electronic properties for high-performance device applications. Further to our work on functionalization of graphene (oxide), we have recently found that simple charge neutralization of the COOH groups in GO with Cs 2 CO 3 could tune the electronic structure of GO, making GO derivatives useful as both hole- and electron-extraction layers in bulk heterojunction (BHJ) solar cells.

Harvesting electrical energy from carbon nanotube yarn twist

Abstract: Mechanical energy harvesters are needed for diverse applications, including self-powered wireless sensors, structural and human health monitoring systems, and the extraction of energy from ocean waves. We report carbon nanotube yarn harvesters that electrochemically convert tensile or torsional mechanical energy into electrical energy without requiring an external bias voltage. Stretching coiled yarns generated 250 watts per kilogram of peak electrical power when cycled up to 30 hertz, as well as up to 41.2 joules per kilogram of electrical energy per mechanical cycle, when normalized to harvester yarn weight. These energy harvesters were used in the ocean to harvest wave energy, combined with thermally driven artificial muscles to convert temperature fluctuations to electrical energy, sewn into textiles for use as self-powered respiration sensors, and used to power a light-emitting diode and to charge a storage capacitor.

The laser additive manufacture of Ti-6Al-4V

Abstract: Laser additive manufacturing (LAM) is a manufacturing technique with cost-reduction potential for titanium aerospace components. The mechanical properties of LAM Ti-6Al-4V have been investigated extensively, but little work on microstructure evolution has been performed to date. The results presented here provide a first look at the relationships between LAM processing parameters and microstructure in as-deposited Ti-6Al-4V.

Microstructure evolution during alpha-beta heat treatment of Ti-6Al-4V

Abstract: A framework for the prediction and control of microstructure evolution during heat treatment of wrought alpha/beta titanium alloys in the two-phase field was established via carefully controlled induction heating trials on Ti-6Al-4V and accompanying mathematical modeling based on diffusion-controlled growth. Induction heat treatment consisted of heating to and soaking at a peak temperature T p=955 °C, controlled cooling at a fixed rate of 11 °C/min, 42 °C/min, or 194 °C/min to a variety of temperatures, and final water quenching. Post-heat-treatment metallography and quantitative image analysis were used to determine the volume fraction of primary (globular) alpha and the nucleation sites/growth behavior of the secondary (platelet) alpha formed during cooling. The growth of the primary alpha during cooling was modeled using an exact solution of the diffusion equation which incorporated diffusion coefficients with a thermodynamic correction for the specific composition of the program material and which took into account the large supersaturations that developed during the heat-treatment process. Agreement between measurements and model predictions was excellent. The model was also used to establish a criterion for describing the initiation and growth of secondary alpha as a function of supersaturation, diffusivity, and cooling rate. The efficacy of the modeling approach was validated by additional heat treatment trials using a peak temperature of 982 °C.