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In order to meet stricter emissions requirements, advanced heavy-duty diesel fuel injection systems will be required to operate at higher pressures and temperatures and in fuels that have poorer lubricity. Scuffing, as a mode of failure, severely limits injector life, and new materials and processes are required to resist scuffing in these more stringent operating conditions. Consequently, there is a need to test the ability of candidate fuel system materials to resist scuffing in fuel-lubricated environments. This paper describes a pin-on-twin reciprocating wear test in which a cylindrical specimen slides, under load, across two fixed, parallel cylindrical specimens that are perpendicular to the axis of the upper sliding specimen. Cylinders of annealed AISI 52100 were tested dry and lubricated by Jet A fuel and on-highway #2 diesel fuel. The friction force was found to give a reliable real-time determination of the onset of scuffing as verified by the morphology of the wear scar. The scar width and surfa...

Covering a light-emitting diode (LED) with quantum dots (QDs) can produce a broad spectrum of white light. However, current techniques for applying QDs to LEDs suffer from a high density of defects and a non-uniform distribution of QDs, which respec-tively diminish the efficiency and quality of emitted light. Oak Ridge National Laboratory (ORNL) has the unique capability to thermally anneal QD structures at extremely high power densities for very short durations. This process, called pulse thermal proc-essing (PTP), reduces the number of point defects while main-taining the size and shape of the original QD nanostructure. Therefore, the efficiency of the QD wavelength conversion layer is improved without altering the emission spectrum defined by the size distribution of the quantum dot nanoparticles. The cur-rent research uses a thermal model to predict annealing tempera-tures during PTP and demonstrates up to a 300% increase in pho-toluminescence for QDs on passive substrates

Pulse thermal processing (PTP) has the capability of processing thin-films and nanoparticles over broad areas utilizing high-density infrared plasma arc lamp technology. Heating rates reaching 600,000°C/s, which is orders of magnitude larger than current state-of-the-art rapid thermal annealing systems, are possible that allow controlled diffusion on the nanoscale. The ability to control heating at these levels permits processing thin-films and nanoparticles on temperature-sensitive substrates such as polymers. The PTP technique has been used to crystallize sputtered amorphous silicon thin-films on sapphire substrates.

In the past decade, additive manufacturing and printed electronics technologies have expanded rapidly on a global scale. As the additive manufacturing techniques have become more capable and affordable, and able to work with a broader range of materials, the machines are increasingly being used to make advanced products at significantly lower costs and risks. The additive manufacturing industry is populated by a broad family of technologies, and the present paper provides an overview of key additive manufacturing technologies and their impact on materials processing, device applications, and future markets. Our R&D efforts on the development of core technologies for the realization of flexible electronics, and 3D microscale structures are also highlighted.

Materials for a CdTe solar cell (ITO/CdS/CdTe/Cu/Pt) were sputtered at room temperature onto kapton, then transformed from resistive layers into a working solar cell by Pulse Thermal Processing (PTP), a novel radiant heat treatment developed at Oak Ridge National Laboratory (ORNL). Unlike conventional device fabrication approaches, the solar cell was a complete device, front-to-back contact, prior to heat treatment. In this proof-of-concept approach, the I-V curves for the as-deposited sputtered materials demonstrate little measurable photovoltaic (PV) activity, but achieved a V oc of 634 mV after PTP. Based on process simulations, it's estimated that the material/device transformation occurred in under 30 ms, while maintaining the kapton substate at temperatures below 250 °C.

The energy distribution and temperature evolution within paintlike systems that are exposed to spectral radiant energy were studied. A complete set of material properties was derived and discussed. Infrared measurements were conducted to obtain experimental data for the temperature in the paint film. The heat flux due to the incident radiation from the plasma arc lamp was measured using a heat flux sensor with a very short response time. A radiative transport model based on spectral four-flux radiation transport equations has been developed for multilayered and semitransparent material systems. Comparisons between the computed and experimental results for temperature show that the energy transport model yields accurate results for a black painted substrate.

Bipolar doping in wide bandgap semiconductors is difficult to achieve under equilibrium conditions because of the spontaneous formation of compensating defects and unfavorable energetics for dopant substitution. In this work, we explored the use of rapid pulse thermal processing for activating nitrogen dopants into acceptor states in ZnO. Low-temperature photoluminescence spectra revealed both acceptor-bound exciton (AX0) and donor-acceptor pair emissions, which present direct evidence for acceptors generated after pulse thermal processing of nitrogen-doped ZnO. This work suggests that pulse thermal processing is potentially an effective method for p-type doping of ZnO.