Ten-year global distribution of downwelling longwave radiation

NASA Astrophysics Data System (ADS)

Pavlakis, K. G.; Hatzidimitriou, D.; Matsoukas, C.; Drakakis, E.; Hatzianastassiou, N.; Vardavas, I.

2003-10-01

Downwelling longwave fluxes, DLFs, have been derived for each month over a ten year period (1984-1993), on a global scale with a resolution of 2.5° × 2.5°. The fluxes were computed using a deterministic model for atmospheric radiation transfer, along with satellite and reanalysis data for the key atmospheric input parameters, i.e. cloud properties, and specific humidity and temperature profiles. The cloud climatologies were taken from the latest released and improved International Satellite Climatology Project D2 series. Specific humidity and temperature vertical profiles were taken from three different reanalysis datasets; NCEP/NCAR, GEOS, and ECMWF (acronyms explained in main text). DLFs were computed for each reanalysis dataset, with differences reaching values as high as 30 Wm-2 in specific regions, particularly over high altitude areas and deserts. However, globally, the agreement is good, with the rms of the difference between the DLFs derived from the different reanalysis datasets ranging from 5 to 7 Wm-2. The results are presented as geographical distributions and as time series of hemispheric and global averages. The DLF time series based on the different reanalysis datasets show similar seasonal and inter-annual variations, and similar anomalies related to the 86/87 El Niño and 89/90 La Niña events. The global ten-year average of the DLF was found to be between 342.2 Wm-2 and 344.3 Wm-2, depending on the dataset. We also conducted a detailed sensitivity analysis of the calculated DLFs to the key input data. Plots are given that can be used to obtain a quick assessment of the sensitivity of the DLF to each of the three key climatic quantities, for specific climatic conditions corresponding to different regions of the globe. Our model downwelling fluxes are validated against available data from ground-based stations distributed over the globe, as given by the Baseline Surface Radiation Network. There is a negative bias of the model fluxes when compared against BSRN fluxes, ranging from -7 to -9 Wm-2, mostly caused by low cloud amount differences between the station and satellite measurements, particularly in cold climates. Finally, we compare our model results with those of other deterministic models and general circulation models.

Ten-year global distribution of downwelling longwave radiation

NASA Astrophysics Data System (ADS)

Pavlakis, K. G.; Hatzidimitriou, D.; Matsoukas, C.; Drakakis, E.; Hatzianastassiou, N.; Vardavas, I.

2004-01-01

Downwelling longwave fluxes, DLFs, have been derived for each month over a ten year period (1984-1993), on a global scale with a spatial resolution of 2.5x2.5 degrees and a monthly temporal resolution. The fluxes were computed using a deterministic model for atmospheric radiation transfer, along with satellite and reanalysis data for the key atmospheric input parameters, i.e. cloud properties, and specific humidity and temperature profiles. The cloud climatologies were taken from the latest released and improved International Satellite Climatology Project D2 series. Specific humidity and temperature vertical profiles were taken from three different reanalysis datasets; NCEP/NCAR, GEOS, and ECMWF (acronyms explained in main text). DLFs were computed for each reanalysis dataset, with differences reaching values as high as 30 Wm-2 in specific regions, particularly over high altitude areas and deserts. However, globally, the agreement is good, with the rms of the difference between the DLFs derived from the different reanalysis datasets ranging from 5 to 7 Wm-2. The results are presented as geographical distributions and as time series of hemispheric and global averages. The DLF time series based on the different reanalysis datasets show similar seasonal and inter-annual variations, and similar anomalies related to the 86/87 El Niño and 89/90 La Niña events. The global ten-year average of the DLF was found to be between 342.2 Wm-2 and 344.3 Wm-2, depending on the dataset. We also conducted a detailed sensitivity analysis of the calculated DLFs to the key input data. Plots are given that can be used to obtain a quick assessment of the sensitivity of the DLF to each of the three key climatic quantities, for specific climatic conditions corresponding to different regions of the globe. Our model downwelling fluxes are validated against available data from ground-based stations distributed over the globe, as given by the Baseline Surface Radiation Network. There is a negative bias of the model fluxes when compared against BSRN fluxes, ranging from -7 to -9 Wm-2, mostly caused by low cloud amount differences between the station and satellite measurements, particularly in cold climates. Finally, we compare our model results with those of other deterministic models and general circulation models.

A gene regulatory network model for floral transition of the shoot apex in maize and its dynamic modeling.

PubMed

Dong, Zhanshan; Danilevskaya, Olga; Abadie, Tabare; Messina, Carlos; Coles, Nathan; Cooper, Mark

2012-01-01

The transition from the vegetative to reproductive development is a critical event in the plant life cycle. The accurate prediction of flowering time in elite germplasm is important for decisions in maize breeding programs and best agronomic practices. The understanding of the genetic control of flowering time in maize has significantly advanced in the past decade. Through comparative genomics, mutant analysis, genetic analysis and QTL cloning, and transgenic approaches, more than 30 flowering time candidate genes in maize have been revealed and the relationships among these genes have been partially uncovered. Based on the knowledge of the flowering time candidate genes, a conceptual gene regulatory network model for the genetic control of flowering time in maize is proposed. To demonstrate the potential of the proposed gene regulatory network model, a first attempt was made to develop a dynamic gene network model to predict flowering time of maize genotypes varying for specific genes. The dynamic gene network model is composed of four genes and was built on the basis of gene expression dynamics of the two late flowering id1 and dlf1 mutants, the early flowering landrace Gaspe Flint and the temperate inbred B73. The model was evaluated against the phenotypic data of the id1 dlf1 double mutant and the ZMM4 overexpressed transgenic lines. The model provides a working example that leverages knowledge from model organisms for the utilization of maize genomic information to predict a whole plant trait phenotype, flowering time, of maize genotypes.

Effect of Thickener and Gasoline Quality on the Properties of Napalm Fuels

DTIC Science & Technology

1945-01-01

6 ’ So H S3 lOCDCCtDOnroO) )««0 0)<E«DO «Hf-IG)IQ|Q0l*-<OO«[> P"iS OOONQHC O «3 IO HHO ’ »O «TOO «XOHCOOilNHIOIOOOIOC- 1’ 01 CD...OOO0JC0O’OCDtf> Cpl0rHl0*OtQlGDtH£CUO>Q O^CUi-KO .O »tOO» »on feCDOl HH(«niQ9 »HHH(0 HHO « I l«KJB* ©HN«(Dlf^V®Ct

Cat's medullary reticulospinal and subnucleus reticularis dorsalis noxious neurons form a coupled neural circuit through collaterals of descending axons

PubMed Central

Leiras, Roberto; Martín-Cora, Francisco; Velo, Patricia; Liste, Tania

2015-01-01

Animals and human beings sense and react to real/potential dangerous stimuli. However, the supraspinal mechanisms relating noxious sensing and nocifensive behavior are mostly unknown. The collateralization and spatial organization of interrelated neurons are important determinants of coordinated network function. Here we electrophysiologically studied medial medullary reticulospinal neurons (mMRF-RSNs) antidromically identified from the cervical cord of anesthetized cats and found that 1) more than 40% (79/183) of the sampled mMRF-RSNs emitted bifurcating axons running within the dorsolateral (DLF) and ventromedial (VMF) ipsilateral fascicles; 2) more than 50% (78/151) of the tested mMRF-RSNs with axons running in the VMF collateralized to the subnucleus reticularis dorsalis (SRD) that also sent ipsilateral descending fibers bifurcating within the DLF and the VMF. This percentage of mMRF collateralization to the SRD increased to more than 81% (53/65) when considering the subpopulation of mMRF-RSNs responsive to noxiously heating the skin; 3) reciprocal monosynaptic excitatory relationships were electrophysiologically demonstrated between noxious sensitive mMRF-RSNs and SRD cells; and 4) injection of the anterograde tracer Phaseolus vulgaris leucoagglutinin evidenced mMRF to SRD and SRD to mMRF projections contacting the soma and proximal dendrites. The data demonstrated a SRD-mMRF network interconnected mainly through collaterals of descending axons running within the VMF, with the subset of noxious sensitive cells forming a reverberating circuit probably amplifying mutual outputs simultaneously regulating motor activity and spinal noxious afferent input. The results provide evidence that noxious stimulation positively engages a reticular SRD-mMRF-SRD network involved in pain-sensory-to-motor transformation and modulation. PMID:26581870

Methodological considerations in estrogen assays of breast fluid and breast tissue.

PubMed

Chatterton, Robert T; Muzzio, Miguel; Heinz, Richard; Gann, Peter H; Khan, Seema A

2015-07-01

Estradiol (E2) in nipple aspirate fluid (NAF), ductal lavage fluid (DLF), and random fine needle aspirates (rFNA) are compared. Quantification was by immunoassay or tandem MS. The percent of women yielding NAF varied between 24% and 48% and for DLF was 86.3%. Variation between ducts within a breast was not less than variation between breasts within women but variation between breasts and within women over time was significantly less than variation between women. Serum E2 was highly significantly different among phases of the menstrual cycle but NAF E2 was not different. The correlation between serum and breast fluid E2 concentrations in premenopausal women had coefficients of determination of less than 15%. The correlation between serum and NAF in studies of postmenopausal women varied greatly and may depend on patient selection. The difference between NAF E2 between pre- and postmenopausal women was only 22%; for rFNA it was non-significantly 44% lower in a similar group of postmenopausal women. Progesterone was 96% and 98% lower in postmenopausal NAF and rFNA samples, respectively. Measurements of E2 in breast fluid or breast tissue appears to provide similar estimates of E2 exposure. E2 levels in breast fluid do not reflect the rapid changes that occur in serum and, thus, serum availability of E2 is only one factor determining its levels in the breast. The similarity of levels between breasts and between ducts suggests that estimates of estrogen exposure does not require multiple samples, however, unavailability of fluid may require rFNA in some cases. Copyright © 2014 Elsevier Inc. All rights reserved.

The impact of hypoglycaemia awareness status on regional brain responses to acute hypoglycaemia in men with type 1 diabetes.

PubMed

Dunn, Joel T; Choudhary, Pratik; Teh, Ming Ming; Macdonald, Ian; Hunt, Katharine F; Marsden, Paul K; Amiel, Stephanie A

2018-05-12

Impaired awareness of hypoglycaemia (IAH) in type 1 diabetes increases the risk of severe hypoglycaemia sixfold and can be resistant to intervention. We explored the impact of IAH on central responses to hypoglycaemia to investigate the mechanisms underlying barriers to therapeutic intervention. We conducted [ 15 O]water positron emission tomography studies of regional brain perfusion during euglycaemia (target 5 mmol/l), hypoglycaemia (achieved level, 2.4 mmol/l) and recovery (target 5 mmol/l) in 17 men with type 1 diabetes: eight with IAH, and nine with intact hypoglycaemia awareness (HA). Hypoglycaemia with HA was associated with increased activation in brain regions including the thalamus, insula, globus pallidus (GP), anterior cingulate cortex (ACC), orbital cortex, dorsolateral frontal (DLF) cortex, angular gyrus and amygdala; deactivation occurred in the temporal and parahippocampal regions. IAH was associated with reduced catecholamine and symptom responses to hypoglycaemia vs HA (incremental AUC: autonomic scores, 26.2 ± 35.5 vs 422.7 ± 237.1; neuroglycopenic scores, 34.8 ± 88.8 vs 478.9 ± 311.1; both p < 0.002). There were subtle differences (p < 0.005, k ≥ 50 voxels) in brain activation at hypoglycaemia, including early differences in the right central operculum, bilateral medial orbital (MO) cortex, and left posterior DLF cortex, with additional differences in the ACC, right GP and post- and pre-central gyri in established hypoglycaemia, and lack of deactivation in temporal regions in established hypoglycaemia. Differences in activation in the post- and pre-central gyri may be expected in people with reduced subjective responses to hypoglycaemia. Alterations in the activity of regions involved in the drive to eat (operculum), emotional salience (MO cortex), aversion (GP) and recall (temporal) suggest differences in the perceived importance and urgency of responses to hypoglycaemia in IAH compared with HA, which may be key to the persistence of the condition.

Financial Impacts of Foot-and-Mouth Disease at Village and National Levels in Lao PDR.

PubMed

Nampanya, S; Khounsy, S; Abila, R; Young, J R; Bush, R D; Windsor, P A

2016-10-01

To assist policies on Foot-and-Mouth Disease (FMD) control in Laos and the Mekong region, the financial impact of recent outbreaks at village and national levels was examined. Village-level impacts were derived from recent research on financial losses due to FMD per smallholder household and number of households with FMD-affected livestock in the village. National-level impacts of FMD were determined from examination of 2011-2013 FMD reported to the Lao Department of Livestock and Fisheries (DLF), with the 2011 epidemic reported separately due to the large number and size of outbreaks of FMD in that year. Estimates of the national financial impact of FMD were based on (i) total FMD financial losses at the village level and (ii) the costs of FMD responses and other related costs at the DLF, provincial and district levels where FMD was reported, but excluding the costs of revenue forgone. A Monte Carlo simulation was utilized to account for likelihood of FMD over- and under-reporting. Foot-and-mouth disease was recorded in four provinces of Phonsaly, Bokeo, Xayyabouli and Champasak in three consecutive years from 2011 to 2013. However, the FMD epidemic in 2011 was more widely distributed and involved 414 villages in 14 provinces, with thousands of cases of morbidity in cattle and buffalo and some mortalities. The estimated financial losses due to FMD in 2011 were USD 30 881(±23 176) at the village level and USD 13 512 291 at the national level based on the number of villages with FMD outbreaks reported. However, when the likelihood of FMD under-reporting was accounted for, the estimated financial losses at the national level could potentially increase to USD 102 094 464 (±52 147 261), being almost 12% of the estimated farm gate value of the national large ruminant herd. These findings confirm that FMD causes substantial financial impacts in villages and to the national economy of Laos, providing justification for sustained investments in FMD control programmes. © 2015 Blackwell Verlag GmbH.

Calibration of the Permo-Triassic Magnetostratigraphic Time Scale: Constraints from the Dewey Lake Formation, West Texas

NASA Astrophysics Data System (ADS)

Chang, S.; Knight, K. B.; Renne, P. R.

2005-12-01

Magnetostratigraphy is potentially a powerful tool for deciphering the high resolution chronostratigraphy of events across the Permo-Triassic boundary, but few well-dated polarity reversals exist to serve as calibration. Red beds of the Dewey Lake Formation (DLF) of West Texas span three reversed polarity intervals (Steiner, 2001) in a section of the DLF at Caprock Canyons State Park, where two tuffs occur. Sanidine separated from these tuffs was analyzed by 40Ar/39Ar methods. Single crystal laser fusion 40Ar/39Ar analyses of 40 grains from the upper tuff yield a weighted mean age of 249.9 ± 2.4 Ma (2σ errors here and throughout). The clustering of single crystal data provides some assurance against xenocrystic contamination. Two age spectra from multigrain sanidine separates from the lower tuff yielded integrated ages of 248.9 ± 2.8 Ma and 249.7 ± 2.8 Ma and consistent plateau ages of 249.2 ± 2.4 Ma and 249.6 ± 2.4 Ma. Two age spectra from multigrain upper tuff sanidines lack strict plateaus but with overall flat age spectra, with integrated ages of 249.7 ± 2.8 Ma and 250.3 ± 2.8 Ma and plateau-like segments (>70% of 39Ar released) with ages of 249.9 ± 2.6 Ma and 249.9 ± 2.6 Ma, respectively. These results, compared with 40Ar/39Ar data (using the same FCs = 28.02 Ma standard calibration) from the GSSP section at Meishan, China, suggest that the Permo-Triassic boundary (249.8 Ma; recalculated from Renne et al., 1995) definitely occurs within the lower Dewey Lake Formation. The two tuffs, which bracket a normal to reverse geomagnetic polarity transition polarity (Steiner, 2001), have indistinguishable ages. The age of this Permo-Triassic polarity transition is thus best represented by the weighed average of their ages, ca. 249.7 Ma (based on accepted calibrations of the 40Ar/39Ar system). Further such constraints will facilitate high-resolution comparison of terrestrial and marine records across this critical time interval.

Fabrication Process for Cantilever Beam Micromechanical Switches

DTIC Science & Technology

1993-08-01

Beam Design ................................................................... 13 B. Chemistry and Materials Used in Cantilever Beam Process...7 3. Photomask levels and composite...pp 410-413. 5 2. Cantilever Beam Fabrication Process The beam fabrication process incorporates four different photomasking levels with 62 processing

Optimum processing parameters for the fabrication of twill flax fabric-reinforced polypropylene (PP) composites

NASA Astrophysics Data System (ADS)

Zuhudi, Nurul Zuhairah Mahmud; Minhat, Mulia; Shamsuddin, Mohd Hafizi; Isa, Mohd Dali; Nur, Nurhayati Mohd

2017-12-01

In recent years, natural fabric thermoplastic composites such as flax have received much attention due to its attractive capabilities for structural applications. It is crucial to study the processing of flax fabric materials in order to achieve good quality and cost-effectiveness in fibre reinforced composites. Though flax fabric has been widely utilized for several years in composite applications due to its high strength and abundance in nature, much work has been concentrated on short flax fibre and very little work focused on using flax fabric. The effectiveness of the flax fabric is expected to give higher strength performance due to its structure but the processing needs to be optimised. Flax fabric composites were fabricated using compression moulding due to its simplicity, gives good surface finish and relatively low cost in terms of labour and production. Further, the impregnation of the polymer into the fabric is easier in this process. As the fabric weave structure contributes to the impregnation quality which leads to the overall performance, the processing parameters of consolidation i.e. pressure, time, and weight fraction of fabric were optimized using the Taguchi method. This optimization enhances the consolidation quality of the composite by improving the composite mechanical properties, three main tests were conducted i.e. tensile, flexural and impact test. It is observed that the processing parameter significantly affected the consolidation and quality of composite.

Optimal fabrication processes for unidirectional metal-matrix composites: A computational simulation

NASA Technical Reports Server (NTRS)

Saravanos, D. A.; Murthy, P. L. N.; Morel, M.

1990-01-01

A method is proposed for optimizing the fabrication process of unidirectional metal matrix composites. The temperature and pressure histories are optimized such that the residual microstresses of the composite at the end of the fabrication process are minimized and the material integrity throughout the process is ensured. The response of the composite during the fabrication is simulated based on a nonlinear micromechanics theory. The optimal fabrication problem is formulated and solved with non-linear programming. Application cases regarding the optimization of the fabrication cool-down phases of unidirectional ultra-high modulus graphite/copper and silicon carbide/titanium composites are presented.

Optimal fabrication processes for unidirectional metal-matrix composites - A computational simulation

NASA Technical Reports Server (NTRS)

Saravanos, D. A.; Murthy, P. L. N.; Morel, M.

1990-01-01

A method is proposed for optimizing the fabrication process of unidirectional metal matrix composites. The temperature and pressure histories are optimized such that the residual microstresses of the composite at the end of the fabrication process are minimized and the material integrity throughout the process is ensured. The response of the composite during the fabrication is simulated based on a nonlinear micromechanics theory. The optimal fabrication problem is formulated and solved with nonlinear programming. Application cases regarding the optimization of the fabrication cool-down phases of unidirectional ultra-high modulus graphite/copper and silicon carbide/titanium composites are presented.

Optimizing The DSSC Fabrication Process Using Lean Six Sigma

NASA Astrophysics Data System (ADS)

Fauss, Brian

Alternative energy technologies must become more cost effective to achieve grid parity with fossil fuels. Dye sensitized solar cells (DSSCs) are an innovative third generation photovoltaic technology, which is demonstrating tremendous potential to become a revolutionary technology due to recent breakthroughs in cost of fabrication. The study here focused on quality improvement measures undertaken to improve fabrication of DSSCs and enhance process efficiency and effectiveness. Several quality improvement methods were implemented to optimize the seven step individual DSSC fabrication processes. Lean Manufacturing's 5S method successfully increased efficiency in all of the processes. Six Sigma's DMAIC methodology was used to identify and eliminate each of the root causes of defects in the critical titanium dioxide deposition process. These optimizations resulted with the following significant improvements in the production process: 1. fabrication time of the DSSCs was reduced by 54 %; 2. fabrication procedures were improved to the extent that all critical defects in the process were eliminated; 3. the quantity of functioning DSSCs fabricated was increased from 17 % to 90 %.

Method for Fabricating Composite Structures Using Pultrusion Processing

NASA Technical Reports Server (NTRS)

Farley, Gary L. (Inventor)

2000-01-01

A method for fabricating composite structures at a low-cost, moderate-to-high production rate. A first embodiment of the method includes employing a continuous press forming fabrication process. A second embodiment of the method includes employing a pultrusion process for obtaining composite structures. The methods include coating yarns with matrix material, weaving the yarn into fabric to produce a continuous fabric supply and feeding multiple layers of net-shaped fabrics having optimally oriented fibers into a debulking tool to form an undebulked preform. The continuous press forming fabrication process includes partially debulking the preform, cutting the partially debulked preform and debulking the partially debulked preform to form a net-shape. An electron-beam or similar technique then cures the structure. The pultrusion fabric process includes feeding the undebulked preform into a heated die and gradually debulking the undebulked preform. The undebulked preform in the heated die changes dimension until a desired cross-sectional dimension is achieved. This process further includes obtaining a net-shaped infiltrated uncured preform, cutting the uncured preform to a desired length and electron-beam curing (or similar technique) the uncured preform. These fabrication methods produce superior structures formed at higher production rates, resulting in lower cost and high structural performance.

Method for Fabricating Composite Structures Using Pultrusion Processing

NASA Technical Reports Server (NTRS)

Farley, Gary L. (Inventor)

2000-01-01

A method for fabricating composite structures at a low-cost, moderate-to-high production rate. A first embodiment of the method includes employing a continuous press forming fabrication process. A second embodiment of the method includes employing a pultrusion process for obtaining composite structures. The methods include coating yarns with matrix material, weaving the yarn into fabric to produce a continuous fabric supply and feeding multiple layers of net-shaped fabrics having optimally oriented fibers into a debulking tool to form an undebulked preform. The continuous press forming fabrication process includes partially debulking the preform, cutting the partially debulked preform and debulking the partially debulked preform to form a netshape. An electron-beam or similar technique then cures the structure. The pultrusion fabric process includes feeding the undebulked preform into a heated die and gradually debulking the undebulked preform. The undebulked preform in the heated die changes dimension until a desired cross-sectional dimension is achieved. This process further includes obtaining a net-shaped infiltrated uncured preform, cutting the uncured preform to a desired length and electronbeam curing (or similar technique) the uncured preform. These fabrication methods produce superior structures formed at higher production rates, resulting in lower cost and high structural performance.

Fabricating a hybrid imaging device

NASA Technical Reports Server (NTRS)

Wadsworth, Mark (Inventor); Atlas, Gene (Inventor)

2003-01-01

A hybrid detector or imager includes two substrates fabricated under incompatible processes. An array of detectors, such as charged-coupled devices, are formed on the first substrate using a CCD fabrication process, such as a buried channel or peristaltic process. One or more charge-converting amplifiers are formed on a second substrate using a CMOS fabrication process. The two substrates are then bonded together to form a hybrid detector.

Fabricating a hybrid imaging device having non-destructive sense nodes

NASA Technical Reports Server (NTRS)

Wadsworth, Mark (Inventor); Atlas, Gene (Inventor)

2001-01-01

A hybrid detector or imager includes two substrates fabricated under incompatible processes. An array of detectors, such as charged-coupled devices, are formed on the first substrate using a CCD fabrication process, such as a buried channel or peristaltic process. One or more charge-converting amplifiers are formed on a second substrate using a CMOS fabrication process. The two substrates are then bonded together to form a hybrid detector.

Development of the Direct Fabrication Process for Plutonium Immobilization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Congdon, J.W.

2001-07-10

The current baseline process for fabricating pucks for the Plutonium Immobilization Program includes granulation of the milled feed prior to compaction. A direct fabrication process was demonstrated that eliminates the need for granulation.

Development and demonstration of manufacturing processes for fabricating graphite/LARC-160 polyimide structural elements, part 4, paragraph B

NASA Technical Reports Server (NTRS)

1980-01-01

A quality assurance program was developed which included specifications for celion/LARC-160 polyimide materials and quality control of materials and processes. The effects of monomers and/or polymer variables and prepeg variables on the processibility of celion/LARC prepeg were included. Processes for fabricating laminates, honeycomb core panels, and chopped fiber moldings were developed. Specimens and conduct tests were fabricated to qualify the processes for fabrication of demonstration components.

Method for Fabricating Composite Structures Including Continuous Press Forming and Pultrusion Processing

NASA Technical Reports Server (NTRS)

Farley, Gary L. (Inventor)

1995-01-01

A method for fabricating composite structures at a low-cost, moderate-to-high production rate is disclosed. A first embodiment of the method includes employing a continuous press forming fabrication process. A second embodiment of the method includes employing a pultrusion process for obtaining composite structures. The methods include coating yarns with matrix material, weaving the yarn into fabric to produce a continuous fabric supply, and feeding multiple layers of net-shaped fabrics having optimally oriented fibers into a debulking tool to form an undebulked preform. The continuous press forming fabrication process includes partially debulking the preform, cutting the partially debulked preform, and debulking the partially debulked preform to form a netshape. An electron-beam or similar technique then cures the structure. The pultrusion fabric process includes feeding the undebulked preform into a heated die and gradually debulking the undebulked preform. The undebulked preform in the heated die changes dimension until a desired cross-sectional dimension is achieved. This process further includes obtaining a net-shaped infiltrated uncured preform, cutting the uncured preform to a desired length, and electron-beam curing (or similar technique) the uncured preform. These fabrication methods produce superior structures formed at higher production rates, resulting in lower cost and high structural performance.

Method for Fabricating Composite Structures Using Continuous Press Forming

NASA Technical Reports Server (NTRS)

Farley, Gary L. (Inventor)

1997-01-01

A method for fabricating composite structures at a low-cost. moderate-to-high production rate. A first embodiment of the method includes employing a continuous press forming fabrication process. A second embodiment of the method includes employing a pultrusion process for obtaining composite structures. The methods include coating yarns with matrix material, weaving the yarn into fabric to produce a continuous fabric supply and feeding multiple layers of net-shaped fabrics having optimally oriented fibers into a debulking tool to form an undebulked preform. The continuous press forming fabrication process includes partially debulking the preform, cutting the partially debulked preform and debulking the partially debulked preform to form a net-shape. An electron-beam or similar technique then cures the structure. The pultrusion fabric process includes feeding the undebulked preform into a heated die and gradually debulking the undebulked preform. The undebulked preform in the heated die changes dimension until a desired cross-sectional dimension is achieved. This process further includes obtaining a net-shaped infiltrated uncured preform, cutting the uncured preform to a desired length and electron-beam curing (or similar technique) the uncured preform. These fabrication methods produce superior structures formed at higher production rates. resulting in lower cost and high structural performance.

Disc resonator gyroscope fabrication process requiring no bonding alignment

NASA Technical Reports Server (NTRS)

Shcheglov, Kirill V. (Inventor)

2010-01-01

A method of fabricating a resonant vibratory sensor, such as a disc resonator gyro. A silicon baseplate wafer for a disc resonator gyro is provided with one or more locating marks. The disc resonator gyro is fabricated by bonding a blank resonator wafer, such as an SOI wafer, to the fabricated baseplate, and fabricating the resonator structure according to a pattern based at least in part upon the location of the at least one locating mark of the fabricated baseplate. MEMS-based processing is used for the fabrication processing. In some embodiments, the locating mark is visualized using optical and/or infrared viewing methods. A disc resonator gyroscope manufactured according to these methods is described.

Low cost damage tolerant composite fabrication

NASA Technical Reports Server (NTRS)

Palmer, R. J.; Freeman, W. T.

1988-01-01

The resin transfer molding (RTM) process applied to composite aircraft parts offers the potential for using low cost resin systems with dry graphite fabrics that can be significantly less expensive than prepreg tape fabricated components. Stitched graphite fabric composites have demonstrated compression after impact failure performance that equals or exceeds that of thermoplastic or tough thermoset matrix composites. This paper reviews methods developed to fabricate complex shape composite parts using stitched graphite fabrics to increase damage tolerance with RTM processes to reduce fabrication cost.

Development and demonstration of manufacturing processes for fabricating graphite/LARC 160 polyimide structural elements

NASA Technical Reports Server (NTRS)

Frost, R. K.; Jones, J. S.; Dynes, P. J.; Wykes, D. H.

1981-01-01

The development and demonstration of manufacturing technologies for the structural application of Celion graphite/LARC-160 polyimide composite material is discussed. Process development and fabrication of demonstration components are discussed. Process development included establishing quality assurance of the basic composite material and processing, nondestructive inspection of fabricated components, developing processes for specific structural forms, and qualification of processes through mechanical testing. Demonstration components were fabricated. The demonstration components consisted of flat laminates, skin/stringer panels, honeycomb panels, chopped fiber compression moldings, and a technology demonstrator segment (TDS) representative of the space shuttle aft body flap.

Application of multi-tone mask technology in photolithographic fabrication of color filter components in LCD

NASA Astrophysics Data System (ADS)

Takada, Yoshihiro; Fukui, Matoko; Sai, Tsunehiro

2008-11-01

Recent progresses in the photoresists and photolithography for LCD industry applications have been primarily driven by the following two factors: advancement in the material performances (high resolution, high contrast ratio, low dielectric constant) for higher display quality, and cost reduction in the fabrication process. Along with crucial demand for cost competitiveness by improving production efficiency, environmental consciousness has been a major priority at fabrication process design to minimize the amount of waste produced. Having said the above, integration of two or more fabrication processes into a single process by using multi-tone mask technology has been the interest of research, due to its obvious advantage of reducing fabrication processes and cost. For example, multi-tone mask technology application has been widely employed on the TFT side to reduce the different types of photomasks being used. Similar trend has been employed on the CF side as well, where application of multi-tone mask technology is being investigated to integrate fabrication of multiple CF micro-components into a single process. In this presentation, we demonstrate a new approach of fabricating photospacer and peripheral CF components (MVA protrusion, sub-photospacers) in a single integrated process through multi-tone mask technology.

Fabrication process for a gradient index x-ray lens

DOEpatents

Bionta, R.M.; Makowiecki, D.M.; Skulina, K.M.

1995-01-17

A process is disclosed for fabricating high efficiency x-ray lenses that operate in the 0.5-4.0 keV region suitable for use in biological imaging, surface science, and x-ray lithography of integrated circuits. The gradient index x-ray optics fabrication process broadly involves co-sputtering multi-layers of film on a wire, followed by slicing and mounting on block, and then ion beam thinning to a thickness determined by periodic testing for efficiency. The process enables the fabrication of transmissive gradient index x-ray optics for the 0.5-4.0 keV energy range. This process allows the fabrication of optical elements for the next generation of imaging and x-ray lithography instruments in the soft x-ray region. 13 figures.

U-10Mo Baseline Fuel Fabrication Process Description

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hubbard, Lance R.; Arendt, Christina L.; Dye, Daniel F.

This document provides a description of the U.S. High Power Research Reactor (USHPRR) low-enriched uranium (LEU) fuel fabrication process. This document is intended to be used in conjunction with the baseline process flow diagram (PFD) presented in Appendix A. The baseline PFD is used to document the fabrication process, communicate gaps in technology or manufacturing capabilities, convey alternatives under consideration, and as the basis for a dynamic simulation model of the fabrication process. The simulation model allows for the assessment of production rates, costs, and manufacturing requirements (manpower, fabrication space, numbers and types of equipment, etc.) throughout the lifecycle ofmore » the USHPRR program. This document, along with the accompanying PFD, is updated regularly« less

Fabrication process for a gradient index x-ray lens

DOEpatents

Bionta, Richard M.; Makowiecki, Daniel M.; Skulina, Kenneth M.

1995-01-01

A process for fabricating high efficiency x-ray lenses that operate in the 0.5-4.0 keV region suitable for use in biological imaging, surface science, and x-ray lithography of integrated circuits. The gradient index x-ray optics fabrication process broadly involves co-sputtering multi-layers of film on a wire, followed by slicing and mounting on block, and then ion beam thinning to a thickness determined by periodic testing for efficiency. The process enables the fabrication of transmissive gradient index x-ray optics for the 0.5-4.0 keV energy range. This process allows the fabrication of optical elements for the next generation of imaging and x-ray lithography instruments m the soft x-ray region.

Investigation of the adhesion properties of direct 3D printing of polymers and nanocomposites on textiles: Effect of FDM printing process parameters

NASA Astrophysics Data System (ADS)

Hashemi Sanatgar, Razieh; Campagne, Christine; Nierstrasz, Vincent

2017-05-01

In this paper, 3D printing as a novel printing process was considered for deposition of polymers on synthetic fabrics to introduce more flexible, resource-efficient and cost effective textile functionalization processes than conventional printing process like screen and inkjet printing. The aim is to develop an integrated or tailored production process for smart and functional textiles which avoid unnecessary use of water, energy, chemicals and minimize the waste to improve ecological footprint and productivity. Adhesion of polymer and nanocomposite layers which were 3D printed directly onto the textile fabrics using fused deposition modeling (FDM) technique was investigated. Different variables which may affect the adhesion properties including 3D printing process parameters, fabric type and filler type incorporated in polymer were considered. A rectangular shape according to the peeling standard was designed as 3D computer-aided design (CAD) to find out the effect of the different variables. The polymers were printed in different series of experimental design: nylon on polyamide 66 (PA66) fabrics, polylactic acid (PLA) on PA66 fabric, PLA on PLA fabric, and finally nanosize carbon black/PLA (CB/PLA) and multi-wall carbon nanotubes/PLA (CNT/PLA) nanocomposites on PLA fabrics. The adhesion forces were quantified using the innovative sample preparing method combining with the peeling standard method. Results showed that different variables of 3D printing process like extruder temperature, platform temperature and printing speed can have significant effect on adhesion force of polymers to fabrics while direct 3D printing. A model was proposed specifically for deposition of a commercial 3D printer Nylon filament on PA66 fabrics. In the following, among the printed polymers, PLA and its composites had high adhesion force to PLA fabrics.

Manufacturing processes for fabricating graphite/PMR 15 polyimide structural elements

NASA Technical Reports Server (NTRS)

Sheppard, C. H.; Hoggatt, J. T.; Symonds, W. A.

1979-01-01

Investigations were conducted to obtain commercially available graphite/PMR-15 polyimide prepreg, develop an autoclave manufacturing process, and demonstrate the process by manufacturing structural elements. Controls were established on polymer, prepreg, composite fabrication, and quality assurance, Successful material quality control and processes were demonstrated by fabricating major structural elements including flat laminates, hat sections, I beam sections, honeycomb sandwich structures, and molded graphite reinforced fittings. Successful fabrication of structural elements and simulated section of the space shuttle aft body flap shows that the graphite/PMR-15 polyimide system and the developed processes are ready for further evaluation in flight test hardware.

Development of a spatially distributed model of fish population density for habitat assessment of rivers

NASA Astrophysics Data System (ADS)

Sui, Pengzhe; Iwasaki, Akito; Ryo, Masahiro; Saavedra, Oliver; Yoshimura, Chihiro

2013-04-01

Flow conditions play an important role in sustaining biodiversity of river ecosystem. However, their relations to freshwater fishes, especially to fish population density, have not been clearly described. This study, therefore, aimed to propose a new methodology to quantitatively link habitat conditions, including flow conditions and other physical conditions, to population density of fish species. We developed a basin-scale fish distribution model by integrating the concept of habitat suitability assessment with a distributed hydrological model (DHM) in order to estimate fish population density with particular attention to flow conditions. Generalized linear model (GLM) was employed to evaluate the relationship between population density of fish species and major environmental factors. The target basin was Sagami River in central Japan, where the river reach was divided into 10 sections by estuary, confluences of tributaries, and river-crossing structures (dams, weirs). The DHM was employed to simulate river discharge from 1998 to 2005, which was used to calculate 10 flow indices including mean discharge, 25th and 75th percentile discharge, duration of low and high flows, number of floods. In addition, 5 water quality parameters and 13 other physical conditions (such as basin area, river width, mean diameter of riverbed material, and number of river-crossing structures upstream and downstream) of each river section were considered as environmental variables. In case of Sagami River, 10 habitat variables among them were then selected based on their correlations to avoid multicollinearity. Finally, the best GLM was developed for each species based on Akaike's information criterion. As results, population densities of 16 fish species in Sagami River were modelled, and correlation coefficients between observed and calculated population densities for 10 species were more than 0.70. The key habitat factors for population density varied among fish species. Minimum discharge (MID) was found to be positively correlated to 9 among 16 fish species. For duration of high and low flows (DHF and DLF), longer DHF/DLF was corresponded to lower population density for 7/6 fish species, respectively, such as Rhinogobius kurodai and Plecoglossus altivelis altivelis. Among physical habitat conditions, sinuosity index (SI, the ratio between actual river section length and straight line length) seems to be the most important parameter for fish population density in Sagami River basin, since it affects 12 out of 16 fish species, followed by mean longitudinal slope (S) and number of downstream dams (NLD). Above results demonstrated the applicability of fish distribution model to provide quantitative information on flow conditions required to maintain fish population, which enabled us to evaluate and project ecological consequences of water resource management policy, such as flood management and water withdrawal.

Fabrication of Ultra-thin Color Films with Highly Absorbing Media Using Oblique Angle Deposition.

PubMed

Yoo, Young Jin; Lee, Gil Ju; Jang, Kyung-In; Song, Young Min

2017-08-29

Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.  We present an advanced method for fabricating ultra-thin color films with improved characteristics. The proposed process addresses several fabrication issues, including large area processing. Specifically, the protocol describes a process for fabricating ultra-thin color films using an electron beam evaporator for oblique angle deposition of germanium (Ge) and gold (Au) on silicon (Si) substrates.  Film porosity produced by the oblique angle deposition induces color changes in the ultra-thin film. The degree of color change depends on factors such as deposition angle and film thickness. Fabricated samples of the ultra-thin color films showed improved color tunability and color purity. In addition, the measured reflectance of the fabricated samples was converted into chromatic values and analyzed in terms of color. Our ultra-thin film fabricating method is expected to be used for various ultra-thin film applications such as flexible color electrodes, thin film solar cells, and optical filters. Also, the process developed here for analyzing the color of the fabricated samples is broadly useful for studying various color structures.

Concurrent tailoring of fabrication process and interphase layer to reduce residual stresses in metal matrix composites

NASA Technical Reports Server (NTRS)

Saravanos, D. A.; Chamis, C. C.; Morel, M.

1991-01-01

A methodology is presented to reduce the residual matrix stresses in continuous fiber metal matrix composites (MMC) by optimizing the fabrication process and interphase layer characteristics. The response of the fabricated MMC was simulated based on nonlinear micromechanics. Application cases include fabrication tailoring, interphase tailoring, and concurrent fabrication-interphase optimization. Two composite systems, silicon carbide/titanium and graphite/copper, are considered. Results illustrate the merits of each approach, indicate that concurrent fabrication/interphase optimization produces significant reductions in the matrix residual stresses and demonstrate the strong coupling between fabrication and interphase tailoring.

Film Delivery Module For Fiber Placement Fabrication of Hybridized Composite Structures

NASA Technical Reports Server (NTRS)

Hulcher, Anthony Bruce; Young, Greg

2005-01-01

A new fabrication technology has been developed at the NASA Marshall Space Flight Center that will allow for the fabrication of hybridized composite structures using fiber placement processing. This technology was originally developed in response to a need to address the issue of hydrogen permeation and microcracking in cryogenic propellant tanks. Numerous thin polymeric and metallized films were investigated under low temperatures conditions for use as barrier films in a composite tank. Manufacturing studies conducted at that time did not address the processing issues related to fabrication of a hybridized tank wall. A film processing head was developed that will allow for the processing of thin polymeric and metallized films, metallic foils, and adhesives using fiber placement processing machinery. The film head is designed to enable the simultaneous processing of film materials and composite tape/tow during the composite part layup process and is also capable of processing the film during an independent operation. Several initial demonstrations were conducted to assess the performance of the film module device. Such assessments included film strip lay-up accuracy, capability to fabricate panels having internal film liners, and fabrication of laminates with embedded film layers.

A Fully Contained Resin Infusion Process for Fiber-Reinforced Polymer Composite Fabrication and Repair

DTIC Science & Technology

2013-01-01

Figures iv  Acknowledgments v  1.  Introduction 1  2.  Experimental 2  2.1  Composite Laminate Fabrication...2 Figure 2. Image of fiberglass composite being fabricated using VARTM processing. 2. Experimental 2.1 Composite Laminate Fabrication...style 5 × 5 plain 5 weave prepreg S-2 fiberglass fabric and a honeycomb core cured in an autoclave, much like the composite parts fielded in

Simulation of materials processing: Fantasy or reality?

NASA Technical Reports Server (NTRS)

Jenkins, Thomas J.; Bright, Victor M.

1994-01-01

This experiment introduces students to the application of computer-aided design (CAD) and analysis of materials processing in the context of integrated circuit (IC) fabrication. The fabrication of modern IC's is a complex process which consists of several sequential steps. These steps involve the precise control of processing variables such as temperature, humidity, and ambient gas composition. In essence, the particular process employed during the fabrication becomes a 'recipe'. Due to economic and other considerations, CAD is becoming an indispensable part of the development of new recipes for IC fabrication. In particular, this experiment permits the students to explore the CAD of the thermal oxidation of silicon.

Design and fabrication of bismith-silicate photonic crystal fiber

NASA Astrophysics Data System (ADS)

Hasegawa, Tomoharu

2012-09-01

The process of design and fabrication of bismuth-silicate photonic crystal fiber (Bi-PCF) is reported. The Bi-PCF was fabricated by stack and draw method. This is the first trial of the fabrication of photonic crystal fiber made of bismuth-based glass with stack and draw method. The Bi-PCF structure was designed to reduce group-velocity-dispersion (GVD) in a plausible process. Thermal properties of the glass are investigated to establish the fabrication process. The applying pressure and pumping in fiber preform preparation were effectively utilized to control the air-hole diameter and arrangement. The fabricated Bi-PCF shows the well reduced GVD as the numerical calculation predicted. Fusion splicing between Bi-PCF and SMF-28 was also demonstrated.

Design and fabrication of label-free biochip using a guided mode resonance filter with nano grating structures by injection molding process.

PubMed

Cho, E; Kim, B; Choi, S; Han, J; Jin, J; Han, J; Lim, J; Heo, Y; Kim, S; Sung, G Y; Kang, S

2011-01-01

This paper introduces technology to fabricate a guided mode resonance filter biochip using injection molding. Of the various nanofabrication processes that exist, injection molding is the most suitable for the mass production of polymer nanostructures. Fabrication of a nanograting pattern for guided mode resonance filters by injection molding requires a durable metal stamp, because of the high injection temperature and pressure. Careful consideration of the optimized process parameters is also required to achieve uniform sub-wavelength gratings with high fidelity. In this study, a metallic nanostructure pattern to be used as the stamp for the injection molding process was fabricated using electron beam lithography, a UV nanoimprinting process, and an electroforming process. A one-dimensional nanograting substrate was replicated by injection molding, during which the process parameters were controlled. To evaluate the geometric quality of the injection molded nanograting patterns, the surface profile of the fabricated nanograting for different processing conditions was analyzed using an atomic force microscope and a scanning electron microscope. Finally, to demonstrate the feasibility of the proposed process for fabricating guided mode resonance filter biochips, a high-refractive-index material was deposited on the polymer nanograting and its guided mode resonance characteristics were analyzed.

Fabrication of self-assembled photonic-crystal structures by centrifugation and spin coating

NASA Astrophysics Data System (ADS)

Xu, Yan; Schneider, Garrett J.; Wetzel, Eric D.; Prather, Dennis W.

2003-11-01

We have developed a simple, low-cost process for the fabrication of high-quality three-dimensional artificial-opal and inverse-opal photonic crystals. The process is based on the self-assembly of a template from a uniform suspension of polystyrene microspheres, which is sintered for added strength and subsequently back-filled with high-index material. The template formation is assisted by a combination of centrifugation and spin-annealing, which requires relatively short process times and inexpensive laboratory equipment. The process has been used to fabricate polycrystalline photonic crystals with photonic stop gaps in the mid-IR portion of the spectrum. Details of the fabrication process and fabricated samples will be presented. In addition, Fourier-transform IR reflection spectroscopy has been used to characterize the samples; the results are shown to be in excellent agreement with band structure diffraction calculations.

Multi-Step Deep Reactive Ion Etching Fabrication Process for Silicon-Based Terahertz Components

NASA Technical Reports Server (NTRS)

Reck, Theodore (Inventor); Perez, Jose Vicente Siles (Inventor); Lee, Choonsup (Inventor); Cooper, Ken B. (Inventor); Jung-Kubiak, Cecile (Inventor); Mehdi, Imran (Inventor); Chattopadhyay, Goutam (Inventor); Lin, Robert H. (Inventor); Peralta, Alejandro (Inventor)

2016-01-01

A multi-step silicon etching process has been developed to fabricate silicon-based terahertz (THz) waveguide components. This technique provides precise dimensional control across multiple etch depths with batch processing capabilities. Nonlinear and passive components such as mixers and multipliers waveguides, hybrids, OMTs and twists have been fabricated and integrated into a small silicon package. This fabrication technique enables a wafer-stacking architecture to provide ultra-compact multi-pixel receiver front-ends in the THz range.

Comparison of resin film infusion, resin transfer molding, and consolidation of textile preforms for primary aircraft structure

NASA Technical Reports Server (NTRS)

Suarez, J.; Dastin, S.

1992-01-01

Innovative design concepts and cost effective fabrication processes were developed for damage tolerant primary structures that can perform at a design ultimate strain level of 6000 micro inch/inch. Attention focused on the use of textile high performance fiber reinforcement concepts that provide improved damage tolerance and out-of-plane load capability, low cost resin film infusion (RFI) and resin transfer molding (RTM) processes, and thermoplastic forming concepts. The fabrication of wing 'Y' spars by four different materials and/or processes methods is described: fabricated using IM7 angle interlock 0 to 90 deg woven preforms with + or - 45 deg plies stitched with Toray high strength graphite thread and processed using RFI and 3501-6 epoxy; fabricated using G40-800 knitted/stitched preforms and processed using RFI and 3501-6 epoxy; fabricated using G40-800 knitted/stitched preforms using RTM and Tactix 123/H41 epoxy; and fabricated preforms using AS4(6K)/PEEK 150 g commingled angle interlock 0 to 90 deg woven preforms with + or - 45 deg commingled plies stitched using high strength graphite thread and processed by consolidation. Structural efficiency, processability, and acquisition cost are compared.

Silicon solar cell process. Development, fabrication and analysis

NASA Technical Reports Server (NTRS)

Yoo, H. I.; Iles, P. A.; Tanner, D. P.

1978-01-01

Solar cells were fabricated from unconventional silicon sheets, and the performances were characterized with an emphasis on statistical evaluation. A number of solar cell fabrication processes were used and conversion efficiency was measured under AMO condition at 25 C. Silso solar cells using standard processing showed an average efficiency of about 9.6%. Solar cells with back surface field process showed about the same efficiency as the cells from standard process. Solar cells from grain boundary passivation process did not show any improvements in solar cell performance.

A novel fabrication method for suspended high-aspect-ratio microstructures

NASA Astrophysics Data System (ADS)

Yang, Yao-Joe; Kuo, Wen-Cheng

2005-11-01

Suspended high-aspect-ratio structures (suspended HARS) are widely used for MEMS devices such as micro-gyroscopes, micro-accelerometers, optical switches and so on. Various fabrication methods, such as SOI, SCREAM, AIM, SBM and BELST processes, were proposed to fabricate HARS. However, these methods focus on the fabrication of suspended microstructures with relatively small widths of trench opening (e.g. less than 10 µm). In this paper, we propose a novel process for fabricating very high-aspect-ratio suspended structures with large widths of trench opening using photoresist as an etching mask. By enhancing the microtrenching effect, we can easily release the suspended structure without thoroughly removing the floor polymer inside the trenches for the cases with a relatively small trench aspect ratio. All the process steps can be integrated into a single-run single-mask ICP-RIE process, which effectively reduces the process complexity and fabrication cost. We also discuss the phenomenon of corner erosion, which results in the undesired etching of silicon structures during the structure-releasing step. By using the proposed process, 100 µm thick suspended structures with the trench aspect ratio of about 20 are demonstrated. Also, the proposed process can be used to fabricate devices for applications which require large in-plane displacement. This paper was orally presented in the Transducers'05, Seoul, Korea (paper ID: 3B1.3).

Fabricating capacitive micromachined ultrasonic transducers with a novel silicon-nitride-based wafer bonding process.

PubMed

Logan, Andrew; Yeow, John T W

2009-05-01

We report the fabrication and experimental testing of 1-D 23-element capacitive micromachined ultrasonic transducer (CMUT) arrays that have been fabricated using a novel wafer-bonding process whereby the membrane and the insulation layer are both silicon nitride. The membrane and cell cavities are deposited and patterned on separate wafers and fusion-bonded in a vacuum environment to create CMUT cells. A user-grown silicon-nitride membrane layer avoids the need for expensive silicon-on-insulator (SOI) wafers, reduces parasitic capacitance, and reduces dielectric charging. It allows more freedom in selecting the membrane thickness while also providing the benefits of wafer-bonding fabrication such as excellent fill factor, ease of vacuum sealing, and a simplified fabrication process when compared with the more standard sacrificial release process. The devices fabricated have a cell diameter of 22 microm, a membrane thickness of 400 nm, a gap depth of 150 nm, and an insulation thickness of 250 nm. The resonant frequency of the CMUT in air is 17 MHz and has an attenuation compensated center frequency of approximately 9 MHz in immersion with a -6 dB fractional bandwidth of 123%. This paper presents the fabrication process and some characterization results.

Study on Single-yarn Pullout Test of Ballistic Resistant Fabric under Different Preloads

NASA Astrophysics Data System (ADS)

Fang, Q. C.; Lei, Z. K.; Y Qin, F.; Li, W. K.; Bai, R. X.

2017-12-01

During bullet penetrating fabric, the pull-out force of yarn in fabric is related to the impact resistance of fabric when the yarn is pulled out from the fabric. The complex uncrimping and friction slip behavior occur during the yarn pullout process, which is critical to learn the impact resistance of fabric. Based on digital image correlation technique, the deformation behavior of Kevlar 49 fabric subjected to preload during the single-yarn pullout process was studied in this paper. The pullout force and displacement curve shows a straight rise and an oscillated decrease. In the linear rise stage, the yarn uncrimping causes a static friction effect. The maximum of the pullout force is not linearly increased with the preload. In the oscillating descending stage, the local descent of the pullout force indicates that the yarn end is gradually withdrawn from the fabric, and the local rise indicates that the yarn end moves to the next weft/warp interaction until the yarn is completely pulled out. The shear deformation of fabric corresponds to the single-yarn pullout process.

Fabrication of High Temperature Cermet Materials for Nuclear Thermal Propulsion

NASA Technical Reports Server (NTRS)

Hickman, Robert; Panda, Binayak; Shah, Sandeep

2005-01-01

Processing techniques are being developed to fabricate refractory metal and ceramic cermet materials for Nuclear Thermal Propulsion (NTP). Significant advances have been made in the area of high-temperature cermet fuel processing since RoverNERVA. Cermet materials offer several advantages such as retention of fission products and fuels, thermal shock resistance, hydrogen compatibility, high conductivity, and high strength. Recent NASA h d e d research has demonstrated the net shape fabrication of W-Re-HfC and other refractory metal and ceramic components that are similar to UN/W-Re cermet fuels. This effort is focused on basic research and characterization to identify the most promising compositions and processing techniques. A particular emphasis is being placed on low cost processes to fabricate near net shape parts of practical size. Several processing methods including Vacuum Plasma Spray (VPS) and conventional PM processes are being evaluated to fabricate material property samples and components. Surrogate W-Re/ZrN cermet fuel materials are being used to develop processing techniques for both coated and uncoated ceramic particles. After process optimization, depleted uranium-based cermets will be fabricated and tested to evaluate mechanical, thermal, and hot H2 erosion properties. This paper provides details on the current results of the project.

Fabrication of single domain GdBCO bulk superconductors by a new modified TSIG technique

NASA Astrophysics Data System (ADS)

Yang, W. M.; Zhi, X.; Chen, S. L.; Wang, M.; Li, J. W.; Ma, J.; Chao, X. X.

2014-01-01

Single domain GdBCO bulk superconductors have been fabricated with new and traditional solid phases by a top seeded infiltration and growth (TSIG) process technique. In the conventional TSIG process, three types of powders, such as Gd2BaCuO5, GdBa2Cu3O7-x and Ba3Cu5O8, must be prepared, but in our new modified TSIG technique, only BaCuO2 powders are required during the fabrication of the single domain GdBCO bulk superconductors. The solid phase used in the conventional process is Gd2BaCuO5 instead of the solid phase (Gd2O3 + BaCuO2) utilized in the new process. The liquid phase used in the conventional process is a mixture of (GdBa2Cu3O7-x + Ba3Cu5O8), and the liquid phase in the new process is a mixture of (Gd2O3 + 10BaCuO2 + 6CuO). Single domain GdBCO bulk superconductors have been fabricated with the new solid and liquid phases. The levitation force of the GdBCO bulk samples fabricated by the new solid phase is 28 N, which is slightly higher than that of the samples fabricated using the conventional solid phases (26 N). The microstructure and the levitation force of the samples indicate that this new method can greatly simplify the fabrication process, introduce nanometer-sized flux centers, improve the levitation force and working efficiency, and greatly reduce the cost of fabrication of single domain GdBCO bulk superconductors by the TSIG process.

Ultrasonic imaging system for in-process fabric defect detection

DOEpatents

Sheen, Shuh-Haw; Chien, Hual-Te; Lawrence, William P.; Raptis, Apostolos C.

1997-01-01

An ultrasonic method and system are provided for monitoring a fabric to identify a defect. A plurality of ultrasonic transmitters generate ultrasonic waves relative to the fabric. An ultrasonic receiver means responsive to the generated ultrasonic waves from the transmitters receives ultrasonic waves coupled through the fabric and generates a signal. An integrated peak value of the generated signal is applied to a digital signal processor and is digitized. The digitized signal is processed to identify a defect in the fabric. The digitized signal processing includes a median value filtering step to filter out high frequency noise. Then a mean value and standard deviation of the median value filtered signal is calculated. The calculated mean value and standard deviation are compared with predetermined threshold values to identify a defect in the fabric.

Design, fabrication and characterization of a poly-silicon PN junction

NASA Astrophysics Data System (ADS)

Tower, Jason D.

This thesis details the design, fabrication, and characterization of a PN junction formed from p-type mono-crystalline silicon and n-type poly-crystalline silicon. The primary product of this project was a library of standard operating procedures (SOPs) for the fabrication of such devices, laying the foundations for future work and the development of a class in fabrication processes. The fabricated PN junction was characterized; in particular its current-voltage relationship was measured and fit to models. This characterization was to determine whether or not the fabrication process could produce working PN junctions with acceptable operational parameters.

ITER Central Solenoid Module Fabrication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, John

The fabrication of the modules for the ITER Central Solenoid (CS) has started in a dedicated production facility located in Poway, California, USA. The necessary tools have been designed, built, installed, and tested in the facility to enable the start of production. The current schedule has first module fabrication completed in 2017, followed by testing and subsequent shipment to ITER. The Central Solenoid is a key component of the ITER tokamak providing the inductive voltage to initiate and sustain the plasma current and to position and shape the plasma. The design of the CS has been a collaborative effort betweenmore » the US ITER Project Office (US ITER), the international ITER Organization (IO) and General Atomics (GA). GA’s responsibility includes: completing the fabrication design, developing and qualifying the fabrication processes and tools, and then completing the fabrication of the seven 110 tonne CS modules. The modules will be shipped separately to the ITER site, and then stacked and aligned in the Assembly Hall prior to insertion in the core of the ITER tokamak. A dedicated facility in Poway, California, USA has been established by GA to complete the fabrication of the seven modules. Infrastructure improvements included thick reinforced concrete floors, a diesel generator for backup power, along with, cranes for moving the tooling within the facility. The fabrication process for a single module requires approximately 22 months followed by five months of testing, which includes preliminary electrical testing followed by high current (48.5 kA) tests at 4.7K. The production of the seven modules is completed in a parallel fashion through ten process stations. The process stations have been designed and built with most stations having completed testing and qualification for carrying out the required fabrication processes. The final qualification step for each process station is achieved by the successful production of a prototype coil. Fabrication of the first ITER module is in progress. The seven modules will be individually shipped to Cadarache, France upon their completion. This paper describes the processes and status of the fabrication of the CS Modules for ITER.« less

A Highly Controllable Electrochemical Anodization Process to Fabricate Porous Anodic Aluminum Oxide Membranes

NASA Astrophysics Data System (ADS)

Lin, Yuanjing; Lin, Qingfeng; Liu, Xue; Gao, Yuan; He, Jin; Wang, Wenli; Fan, Zhiyong

2015-12-01

Due to the broad applications of porous alumina nanostructures, research on fabrication of anodized aluminum oxide (AAO) with nanoporous structure has triggered enormous attention. While fabrication of highly ordered nanoporous AAO with tunable geometric features has been widely reported, it is known that its growth rate can be easily affected by the fluctuation of process conditions such as acid concentration and temperature during electrochemical anodization process. To fabricate AAO with various geometric parameters, particularly, to realize precise control over pore depth for scientific research and commercial applications, a controllable fabrication process is essential. In this work, we revealed a linear correlation between the integrated electric charge flow throughout the circuit in the stable anodization process and the growth thickness of AAO membranes. With this understanding, we developed a facile approach to precisely control the growth process of the membranes. It was found that this approach is applicable in a large voltage range, and it may be extended to anodization of other metal materials such as Ti as well.

A Highly Controllable Electrochemical Anodization Process to Fabricate Porous Anodic Aluminum Oxide Membranes.

PubMed

Lin, Yuanjing; Lin, Qingfeng; Liu, Xue; Gao, Yuan; He, Jin; Wang, Wenli; Fan, Zhiyong

2015-12-01

Due to the broad applications of porous alumina nanostructures, research on fabrication of anodized aluminum oxide (AAO) with nanoporous structure has triggered enormous attention. While fabrication of highly ordered nanoporous AAO with tunable geometric features has been widely reported, it is known that its growth rate can be easily affected by the fluctuation of process conditions such as acid concentration and temperature during electrochemical anodization process. To fabricate AAO with various geometric parameters, particularly, to realize precise control over pore depth for scientific research and commercial applications, a controllable fabrication process is essential. In this work, we revealed a linear correlation between the integrated electric charge flow throughout the circuit in the stable anodization process and the growth thickness of AAO membranes. With this understanding, we developed a facile approach to precisely control the growth process of the membranes. It was found that this approach is applicable in a large voltage range, and it may be extended to anodization of other metal materials such as Ti as well.

Peel-and-Stick: Fabricating Thin Film Solar Cell on Universal Substrates

PubMed Central

Lee, Chi Hwan; Kim, Dong Rip; Cho, In Sun; William, Nemeth; Wang, Qi; Zheng, Xiaolin

2012-01-01

Fabrication of thin-film solar cells (TFSCs) on substrates other than Si and glass has been challenging because these nonconventional substrates are not suitable for the current TFSC fabrication processes due to poor surface flatness and low tolerance to high temperature and chemical processing. Here, we report a new peel-and-stick process that circumvents these fabrication challenges by peeling off the fully fabricated TFSCs from the original Si wafer and attaching TFSCs to virtually any substrates regardless of materials, flatness and rigidness. With the peel-and-stick process, we integrated hydrogenated amorphous silicon (a-Si:H) TFSCs on paper, plastics, cell phone and building windows while maintaining the original 7.5% efficiency. The new peel-and-stick process enables further reduction of the cost and weight for TFSCs and endows TFSCs with flexibility and attachability for broader application areas. We believe that the peel-and-stick process can be applied to thin film electronics as well. PMID:23277871

Peel-and-Stick: Fabricating Thin Film Solar Cell on Universal Substrates

NASA Astrophysics Data System (ADS)

Lee, Chi Hwan; Kim, Dong Rip; Cho, In Sun; William, Nemeth; Wang, Qi; Zheng, Xiaolin

2012-12-01

Fabrication of thin-film solar cells (TFSCs) on substrates other than Si and glass has been challenging because these nonconventional substrates are not suitable for the current TFSC fabrication processes due to poor surface flatness and low tolerance to high temperature and chemical processing. Here, we report a new peel-and-stick process that circumvents these fabrication challenges by peeling off the fully fabricated TFSCs from the original Si wafer and attaching TFSCs to virtually any substrates regardless of materials, flatness and rigidness. With the peel-and-stick process, we integrated hydrogenated amorphous silicon (a-Si:H) TFSCs on paper, plastics, cell phone and building windows while maintaining the original 7.5% efficiency. The new peel-and-stick process enables further reduction of the cost and weight for TFSCs and endows TFSCs with flexibility and attachability for broader application areas. We believe that the peel-and-stick process can be applied to thin film electronics as well.

Design architecture of double spiral interdigitated electrode with back gate electrode for biosensor application

NASA Astrophysics Data System (ADS)

Fathil, M. F. M.; Arshad, M. K. Md.; Hashim, U.; Ruslinda, A. R.; Gopinath, Subash C. B.; M. Nuzaihan M., N.; Ayub, R. M.; Adzhri, R.; Zaki, M.; Azman, A. H.

2016-07-01

This paper presents the preparation method of photolithography chrome mask design used in fabrication process of double spiral interdigitated electrode with back gate biasing based biosensor. By learning the fabrication process flow of the biosensor, the chrome masks are designed through drawing using the AutoCAD software. The overall width and length of the device is optimized at 7.0 mm and 10.0 mm, respectively. Fabrication processes of the biosensor required three chrome masks, which included back gate opening, spiral IDE formation, and passivation area formation. The complete chrome masks design will be sent for chrome mask fabrication and for future use in biosensor fabrication.

19 CFR 10.242 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-04-01

... knitting machine. Several components with finished edges may be linked by yarn or thread as they are... reference to fabric components, means that all of the production processes, starting with the production of... fabric(s), means that all of the production processes, starting with polymers, fibers, filaments, textile...

19 CFR 10.242 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-04-01

... knitting machine. Several components with finished edges may be linked by yarn or thread as they are... reference to fabric components, means that all of the production processes, starting with the production of... fabric(s), means that all of the production processes, starting with polymers, fibers, filaments, textile...

19 CFR 10.212 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-04-01

... in” means that all of the components of the textile or apparel article (including thread, decorative...,” when used with reference to fabric(s), means that all of the production processes, starting with... with a fabric by a weaving, knitting, needling, tufting, felting, entangling or other process, took...

19 CFR 10.242 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-04-01

... knitting machine. Several components with finished edges may be linked by yarn or thread as they are... reference to fabric components, means that all of the production processes, starting with the production of... fabric(s), means that all of the production processes, starting with polymers, fibers, filaments, textile...

19 CFR 10.212 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-04-01

... in” means that all of the components of the textile or apparel article (including thread, decorative...,” when used with reference to fabric(s), means that all of the production processes, starting with... with a fabric by a weaving, knitting, needling, tufting, felting, entangling or other process, took...

19 CFR 10.212 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-04-01

... in” means that all of the components of the textile or apparel article (including thread, decorative...,” when used with reference to fabric(s), means that all of the production processes, starting with... with a fabric by a weaving, knitting, needling, tufting, felting, entangling or other process, took...

19 CFR 10.242 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

... knitting machine. Several components with finished edges may be linked by yarn or thread as they are... reference to fabric components, means that all of the production processes, starting with the production of... fabric(s), means that all of the production processes, starting with polymers, fibers, filaments, textile...

19 CFR 10.242 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-04-01

... knitting machine. Several components with finished edges may be linked by yarn or thread as they are... reference to fabric components, means that all of the production processes, starting with the production of... fabric(s), means that all of the production processes, starting with polymers, fibers, filaments, textile...

19 CFR 10.212 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-04-01

... in” means that all of the components of the textile or apparel article (including thread, decorative...,” when used with reference to fabric(s), means that all of the production processes, starting with... with a fabric by a weaving, knitting, needling, tufting, felting, entangling or other process, took...

19 CFR 10.212 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

... in” means that all of the components of the textile or apparel article (including thread, decorative...,” when used with reference to fabric(s), means that all of the production processes, starting with... with a fabric by a weaving, knitting, needling, tufting, felting, entangling or other process, took...

Combined micromechanical and fabrication process optimization for metal-matrix composites

NASA Technical Reports Server (NTRS)

Morel, M.; Saravanos, D. A.; Chamis, C. C.

1991-01-01

A method is presented to minimize the residual matrix stresses in metal matrix composites. Fabrication parameters such as temperature and consolidation pressure are optimized concurrently with the characteristics (i.e., modulus, coefficient of thermal expansion, strength, and interphase thickness) of a fiber-matrix interphase. By including the interphase properties in the fabrication process, lower residual stresses are achievable. Results for an ultra-high modulus graphite (P100)/copper composite show a reduction of 21 percent for the maximum matrix microstress when optimizing the fabrication process alone. Concurrent optimization of the fabrication process and interphase properties show a 41 percent decrease in the maximum microstress. Therefore, this optimization method demonstrates the capability of reducing residual microstresses by altering the temperature and consolidation pressure histories and tailoring the interphase properties for an improved composite material. In addition, the results indicate that the consolidation pressures are the most important fabrication parameters, and the coefficient of thermal expansion is the most critical interphase property.

Concurrent micromechanical tailoring and fabrication process optimization for metal-matrix composites

NASA Technical Reports Server (NTRS)

Morel, M.; Saravanos, D. A.; Chamis, Christos C.

1990-01-01

A method is presented to minimize the residual matrix stresses in metal matrix composites. Fabrication parameters such as temperature and consolidation pressure are optimized concurrently with the characteristics (i.e., modulus, coefficient of thermal expansion, strength, and interphase thickness) of a fiber-matrix interphase. By including the interphase properties in the fabrication process, lower residual stresses are achievable. Results for an ultra-high modulus graphite (P100)/copper composite show a reduction of 21 percent for the maximum matrix microstress when optimizing the fabrication process alone. Concurrent optimization of the fabrication process and interphase properties show a 41 percent decrease in the maximum microstress. Therefore, this optimization method demonstrates the capability of reducing residual microstresses by altering the temperature and consolidation pressure histories and tailoring the interphase properties for an improved composite material. In addition, the results indicate that the consolidation pressures are the most important fabrication parameters, and the coefficient of thermal expansion is the most critical interphase property.

Screen printing of a capacitive cantilever-based motion sensor on fabric using a novel sacrificial layer process for smart fabric applications

NASA Astrophysics Data System (ADS)

Wei, Yang; Torah, Russel; Yang, Kai; Beeby, Steve; Tudor, John

2013-07-01

Free-standing cantilevers have been fabricated by screen printing sacrificial and structural layers onto a standard polyester cotton fabric. By printing additional conductive layers, a complete capacitive motion sensor on fabric using only screen printing has been fabricated. This type of free-standing structure cannot currently be fabricated using conventional fabric manufacturing processes. In addition, compared to conventional smart fabric fabrication processes (e.g. weaving and knitting), screen printing offers the advantages of geometric design flexibility and the ability to simultaneously print multiple devices of the same or different designs. Furthermore, a range of active inks exists from the printed electronics industry which can potentially be applied to create many types of smart fabric. Four cantilevers with different lengths have been printed on fabric using a five-layer structure with a sacrificial material underneath the cantilever. The sacrificial layer is subsequently removed at 160 °C for 30 min to achieve a freestanding cantilever above the fabric. Two silver electrodes, one on top of the cantilever and the other on top of the fabric, are used to capacitively detect the movement of the cantilever. In this way, an entirely printed motion sensor is produced on a standard fabric. The motion sensor was initially tested on an electromechanical shaker rig at a low frequency range to examine the linearity and the sensitivity of each design. Then, these sensors were individually attached to a moving human forearm to evaluate more representative results. A commercial accelerometer (Microstrain G-link) was mounted alongside for comparison. The printed sensors have a similar motion response to the commercial accelerometer, demonstrating the potential of a printed smart fabric motion sensor for use in intelligent clothing applications.

Antimicrobial nano-silver non-woven polyethylene terephthalate fabric via an atmospheric pressure plasma deposition process

PubMed Central

Deng, Xiaolong; Yu Nikiforov, Anton; Coenye, Tom; Cools, Pieter; Aziz, Gaelle; Morent, Rino; De Geyter, Nathalie; Leys, Christophe

2015-01-01

An antimicrobial nano-silver non-woven polyethylene terephthalate (PET) fabric has been prepared in a three step process. The fabrics were first pretreated by depositing a layer of organosilicon thin film using an atmospheric pressure plasma system, then silver nano-particles (AgNPs) were incorporated into the fabrics by a dipping-dry process, and finally the nano-particles were covered by a second organosilicon layer of 10-50 nm, which acts as a barrier layer. Different surface characterization techniques like SEM and XPS have been implemented to study the morphology and the chemical composition of the nano-silver fabrics. Based on these techniques, a uniform immobilization of AgNPs in the PET matrix has been observed. The antimicrobial activity of the treated fabrics has also been tested using P. aeruginosa, S. aureus and C. albicans. It reveals that the thickness of the barrier layer has a strong effect on the bacterial reduction of the fabrics. The durability and stability of the AgNPs on the fabrics has also been investigated in a washing process. By doing so, it is confirmed that the barrier layer can effectively prevent the release of AgNPs and that the thickness of the barrier layer is an important parameter to control the silver ions release. PMID:25951432

Fabrication Processes and Mechanical Behavior of CNT/Metal Nanocomposites

DTIC Science & Technology

2013-12-01

process, were investigated and applied for fabrication of CNT/Cu and CNT/Ni nanocomposite powders. The spark plasma sintering process was applied... spark plasma sintering process to fabricate CNT/NiTi and CNT/Al-Cu nanocomposites. It is confirmed that the CNTs were homogeneously dispersed in NiTi...can be seen in Figure 1-1. The CNT/NiTi composite powders were consolidated by spark plasma sintering (SPS, Dr. Sinter Lab., Sumitomo). The CNT/NiTi

Comparison of resin film infusion, resin transfer molding, and consolidation of textile preforms for primary aircraft structure

NASA Technical Reports Server (NTRS)

Suarez, J.; Dastin, S.

1992-01-01

Under NASA's Novel Composites for Wing and Fuselage Applications (NCWFA) Program, Grumman is developing innovative design concepts and cost-effective fabrication processes for damage-tolerant primary structures that can perform at a design ultimate strain level of 6000 micro-inch/inch. Attention has focused on the use of textile high-performance fiber-reinforcement concepts that provide improved damage tolerance and out-of-plane load capability, low-cost resin film infusion (RFI) and resin transfer molding (RTM) processes, and thermoplastic forming concepts. The fabrication of wing 'Y' spars by four different materials/processes methods is described: 'Y' spars fabricated using IM7 angle interlock 0/90 deg woven preforms with +/- 45 deg plies stitched with Toray high-strength graphite thread and processed using RFI and 3501-6 epoxy; 'Y' spars fabricated using G40-800 knitted/stitched preforms and processed using RFI and 3501-6 epoxy; 'Y' spars fabricated using G40-800 knitted/stitched preforms and processed using RTM and Tactix 123/H41 epoxy; and 'Y' spars fabricated using AS4(6k)/PEEK 150-g commingled angle interlock 0/90 deg woven preforms with +/- 45 deg commingled plies stitched using high-strength graphite thread and processed by consolidation. A comparison of the structural efficiency, processability, and projected acquisition cost of these representative spars is presented.

Process for the synthesis of nanophase dispersion-strengthened aluminum alloy

DOEpatents

Barbour, John C.; Knapp, James Arthur; Follstaedt, David Martin; Myers, Samuel Maxwell

1998-12-15

A process for fabricating dispersion-strengthened ceramic-metal composites is claimed. The process comprises in-situ interaction and chemical reaction of a metal in gaseous form with a ceramic producer in plasma form. Such composites can be fabricated with macroscopic dimensions. Special emphasis is placed on fabrication of dispersion-strengthened aluminum oxide-aluminum composites, which can exhibit flow stresses more characteristic of high strength steel.

Piezoelectric Sol-Gel Composite Film Fabrication by Stencil Printing.

PubMed

Kaneko, Tsukasa; Iwata, Kazuki; Kobayashi, Makiko

2015-09-01

Piezoelectric films using sol-gel composites could be useful as ultrasonic transducers in various industrial fields. For sol-gel composite film fabrication, the spray coating technique has been used often because of its adaptability for various substrates. However, the spray technique requires multiple spray coating processes and heating processes and this is an issue of concern, especially for on-site fabrication in controlled areas. Stencil printing has been developed to solve this issue because this method can be used to fabricate thick sol-gel composite films with one coating process. In this study, PbTiO3 (PT)/Pb(Zr,Ti)O3 (PZT) films, PZT/PZT films, and Bi4Ti3O12 (BiT)/PZT films were fabricated by stencil printing, and PT/ PZT films were also fabricated using the spray technique. After fabrication, a thermal cycle test was performed for the samples to compare their ultrasonic performance. The sensitivity and signal-to-noise-ratio (SNR) of the ultrasonic response of PT/PZT fabricated by stencil printing were equivalent to those of PT/PZT fabricated by the spray technique, and better than those of other samples between room temperature and 300°C. Therefore, PT/PZT films fabricated by stencil printing could be a good candidate for nondestructive testing (NDT) ultrasonic transducers from room temperature to 300°C.

Fabrication of flexible grating sensing waveguide based on nano-imprint lithography and micro-replication process

NASA Astrophysics Data System (ADS)

Liu, Yueming; Tian, Weijian; Zhang, Shaojun

2009-05-01

Soft and flexible grating sensing waveguides is urgently demanded in application of micro-bending sensing and surface distortion sensing in medical catheter and smart skin sensing unit etc. Based on Nano-imprint Lithography and micro-replication process, polymer grating waveguides with core size 4μm×20μm and pitch 0.75μm are fabricated successfully in this paper. This novel grating waveguides is soft and flexible enough for related application and with the bio-medical safe feature when used in human body catheter. Fabricated processes are presented including the fabrication of micro mould and UV-replication process, and relative skills are discussed also in this paper.

Low-Cost Detection of Thin Film Stress during Fabrication

NASA Technical Reports Server (NTRS)

Nabors, Sammy A.

2015-01-01

NASA's Marshall Space Flight Center has developed a simple, cost-effective optical method for thin film stress measurements during growth and/or subsequent annealing processes. Stress arising in thin film fabrication presents production challenges for electronic devices, sensors, and optical coatings; it can lead to substrate distortion and deformation, impacting the performance of thin film products. NASA's technique measures in-situ stress using a simple, noncontact fiber optic probe in the thin film vacuum deposition chamber. This enables real-time monitoring of stress during the fabrication process and allows for efficient control of deposition process parameters. By modifying process parameters in real time during fabrication, thin film stress can be optimized or controlled, improving thin film product performance.

Tailored metal matrix composites for high-temperature performance

NASA Technical Reports Server (NTRS)

Morel, M. R.; Saravanos, D. A.; Chamis, C. C.

1992-01-01

A multi-objective tailoring methodology is presented to maximize stiffness and load carrying capacity of a metal matrix cross-ply laminated at elevated temperatures. The fabrication process and fiber volume ratio are used as the design variables. A unique feature is the concurrent effects from fabrication, residual stresses, material nonlinearity, and thermo-mechanical loading on the laminate properties at the post-fabrication phase. For a (0/90)(sub s) graphite/copper laminate, strong coupling was observed between the fabrication process, laminate characteristics, and thermo-mechanical loading. The multi-objective tailoring was found to be more effective than single objective tailoring. Results indicate the potential to increase laminate stiffness and load carrying capacity by controlling the critical parameters of the fabrication process and the laminate.

An efficient nontraditional method of directly converting a cotton fibrous material into a woven-like hydroentangled nonwoven cotton fabric

USDA-ARS?s Scientific Manuscript database

The traditional technology of producing cotton woven fabrics is comprised of about 20 mechanical and chemical processes that generally are costly, slow, inefficient, and environmentally somewhat unfriendly. A modern system, using fewer preparatory processes, of fabricating hydro-entangled cotton and...

Robotic Processing Of Rocket-Engine Nozzles

NASA Technical Reports Server (NTRS)

Gilbert, Jeffrey L.; Maslakowski, John E.; Gutow, David A.; Deily, David C.

1994-01-01

Automated manufacturing cell containing computer-controlled robotic processing system developed to implement some important related steps in fabrication of rocket-engine nozzles. Performs several tedious and repetitive fabrication, measurement, adjustment, and inspection processes and subprocesses now performed manually. Offers advantages of reduced processing time, greater consistency, excellent collection of data, objective inspections, greater productivity, and simplified fixturing. Also affords flexibility: by making suitable changes in hardware and software, possible to modify process and subprocesses. Flexibility makes work cell adaptable to fabrication of heat exchangers and other items structured similarly to rocket nozzles.

Out of the Autoclave Fabrication of LaRC[TradeMark] PETI-9 Polyimide Laminates

NASA Technical Reports Server (NTRS)

Cano, Robert J.; Jensen, Brian J.

2013-01-01

The NASA Langley Research Center developed polyimide system, LaRC PETI-9, has successfully been processed into composites by high temperature vacuum assisted resin transfer molding (HT-VARTM). To extend the application of this high use temperature material to other out-of-autoclave (OOA) processing techniques, the fabrication of PETI- 9 laminates was evaluated using only a vacuum bag and oven cure. A LaRC PETI-9 polyimide solution in NMP was prepared and successfully utilized to fabricate unidirectional IM7 carbon fiber prepreg that was subsequently processed into composites with a vacuum bag and oven cure OOA process. Composite panels of good quality were successfully fabricated and mechanically tested. Processing characteristics, composite panel quality and mechanical properties are presented in this work. The resultant properties are compared to previously developed LaRC material systems processed by both autoclave and OOA techniques including the well characterized, autoclave processed LaRC PETI-5.

Testing of qubit materials and fabrication using superconducting resonators

NASA Astrophysics Data System (ADS)

Kumar, Shwetank; Steffen, Matthias; Divincenzo, David; Keefe, George; Rothwell, Mary Beth; Farinelli, Matthew; Rozen, Jim; Milliken, Frank; Ketchen, Mark

2009-03-01

We will present the results of measurements made on superconducting resonators fabricated using different substrates and superconducting metals. Specifically, the quality factor of these resonators will be shown to be closely related to not only the purity of the substrates and metals used in the process but also to the details of the fabrication. We will demonstrate the change in quality factor of a bare resonator when subjected to the qubit process. Based on our measurements we propose that superconducting resonators may form a test bed for troubleshooting the fabrication process for minimizing the materials related dissipation in the qubits.

Batch fabrication process development for ferrite logic conductors

NASA Technical Reports Server (NTRS)

Heckler, C. H., Jr.; Bhiwandker, N. C.

1972-01-01

A process for fabricating ultrareliable magnetic ferrite logic circuits is described in which the conductors are formed by a combination of two batch type processes - photolithography and electroplating - and a mechanized writing process for completing conductors in the third dimension. Up to 4 turns, through an aperture 1 mm in diameter, are formed by the described process. The number of joints in the conductors is reduced by use of this process to only those which are required for input, output and power connections of a logic block. To demonstrate feasibility, 8-stage magnetic ring counter circuits have been fabricated.

Design and fabrication of a 1-DOF drive mode and 2-DOF sense mode micro-gyroscope using SU-8 based UV-LIGA process

NASA Astrophysics Data System (ADS)

Verma, Payal; Juneja, Sucheta; Savelyev, Dmitry A.; Khonina, Svetlana N.; Gopal, Ram

2016-04-01

This paper presents design and fabrication of a 1-DOF (degree-of-freedom) drive mode and 2-DOF sense mode micro-gyroscope. It is an inherently robust structure and offers a high sense frequency bandwidth. The proposed design utilizes resonance of the1-DOF drive mode oscillator and employs dynamic amplification concept in sense modes to increase the sensitivity while maintaining robustness. The 2-DOF in the sense direction renders the device immune to process imperfections and environmental effects. The design is simulated using FEA software (CoventorWare®). The device is designed considering process compatibility with SU-8 based UV-LIGA process, which is an economical fabrication technique. The complete fabrication process is presented along with SEM images of the fabricated device. The device has 9 µm thick Nickel as the key structural layer with an overall reduced key structure size of 2.2 mm by 2.1 mm.

Vacuum infusion method for woven carbon/Kevlar reinforced hybrid composite

NASA Astrophysics Data System (ADS)

Hashim, N.; Majid, D. L.; Uda, N.; Zahari, R.; Yidris, N.

2017-12-01

The vacuum assisted resin transfer moulding (VaRTM) or Vacuum Infusion (VI) is one of the fabrication methods used for composite materials. Compared to other methods, this process costs lower than using prepregs because it does not need to use the autoclave to cure. Moreover, composites fabricated using this VI method exhibit superior mechanical properties than those made through hand layup process. In this study, the VI method is used in fabricating woven carbon/Kevlar fibre cloth with epoxy matrix. This paper reports the detailed methods on fabricating the hybrid composite using VI process and several precautions that need to be taken to avoid any damage to the properties of the composite material. The result highlights that the successfully fabricated composite has approximately 60% of fibres weight fraction. Since the composites produced by the VI process have a higher fibre percentage, this process should be considered for composites used in applications that are susceptible to the conditions where the fibres need to be the dominant element such as in tension loading.

Fabrication of High Strength Lightweight Metals for Armor and Structural Applications: Large Scale Equal Channel Angular Extrusion Processing of Aluminum 5083 Alloy

DTIC Science & Technology

2017-06-01

ARL-TR-8047 ● JUNE 2017 US Army Research Laboratory Fabrication of High -Strength Lightweight Metals for Armor and Structural...to the originator. ARL-TR-8047 ● JUNE 2017 US Army Research Laboratory Fabrication of High -Strength Lightweight Metals for...Fabrication of High -Strength Lightweight Metals for Armor and Structural Applications: Large-Scale Equal Channel Angular Extrusion Processing of

Fabrication of Large YBCO Superconducting Disks

NASA Technical Reports Server (NTRS)

Koczor, Ronald J.; Noever, David A.; Robertson, Glen A.

1999-01-01

We have undertaken fabrication of large bulk items to develop a repeatable process and to provide test articles in laboratory experiments investigating reported coupling of electromagnetic fields with the local gravity field in the presence of rotating superconducting disks. A successful process was developed which resulted in fabrication of 30 cm diameter annular disks. The disks were fabricated of the superconductor YBa2Cu3O(7-x). Various material parameters of the disks were measured.

Fabrication of amorphous IGZO thin film transistor using self-aligned imprint lithography with a sacrificial layer

NASA Astrophysics Data System (ADS)

Kim, Sung Jin; Kim, Hyung Tae; Choi, Jong Hoon; Chung, Ho Kyoon; Cho, Sung Min

2018-04-01

An amorphous indium-gallium-zinc-oxide (a-IGZO) thin film transistor (TFT) was fabricated by a self-aligned imprint lithography (SAIL) method with a sacrificial photoresist layer. The SAIL is a top-down method to fabricate a TFT using a three-dimensional multilayer etch mask having all pattern information for the TFT. The sacrificial layer was applied in the SAIL process for the purpose of removing the resin residues that were inevitably left when the etch mask was thinned by plasma etching. This work demonstrated that the a-IGZO TFT could be fabricated by the SAIL process with the sacrificial layer. Specifically, the simple fabrication process utilized in this study can be utilized for the TFT with a plasma-sensitive semiconductor such as the a-IGZO and further extended for the roll-to-roll TFT fabrication.

Bismaleimide resins for flame resistant honeycomb sandwich panels

NASA Technical Reports Server (NTRS)

Stenzenberger, H. D.

1978-01-01

Bismaleimide resins are prime candidates for nonflammable aircraft interior panels. Three resin types with different structures and processing characteristics were formulated. Resin M 751 was used to fabricate 100 kg of glass fabric prepregs which were used for the preparation of face sheets for honeycomb sandwich panels. Prepreg characteristics and curing cycles for laminate fabrication are provided. In order to advance beyond the current solvent resin technology for fibre and fabric impregnation, a hot melt solvent-less resin system was prepared and characterized. Preliminary tests were performed to develop a wet bonding process for the fabrication of advanced sandwich honeycomb panels by use of polybismaleimide glass fabric face sheets and polybismaleimide Nomex honeycomb core. B-stage material was used for both the core and the face sheet, providing flatwise tensile properties equivalent to those obtained by the state-of-the-art 3-step process which includes an epoxy adhesive resin.

14 CFR 29.605 - Fabrication methods.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Fabrication methods. 29.605 Section 29.605... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction General § 29.605 Fabrication methods. (a) The methods of fabrication used must produce consistently sound structures. If a fabrication process...

14 CFR 29.605 - Fabrication methods.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Fabrication methods. 29.605 Section 29.605... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction General § 29.605 Fabrication methods. (a) The methods of fabrication used must produce consistently sound structures. If a fabrication process...

14 CFR 29.605 - Fabrication methods.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Fabrication methods. 29.605 Section 29.605... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction General § 29.605 Fabrication methods. (a) The methods of fabrication used must produce consistently sound structures. If a fabrication process...

14 CFR 29.605 - Fabrication methods.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Fabrication methods. 29.605 Section 29.605... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction General § 29.605 Fabrication methods. (a) The methods of fabrication used must produce consistently sound structures. If a fabrication process...

14 CFR 29.605 - Fabrication methods.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fabrication methods. 29.605 Section 29.605... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction General § 29.605 Fabrication methods. (a) The methods of fabrication used must produce consistently sound structures. If a fabrication process...

Effect of Welding Processes on the Microstructure, Mechanical Properties and Residual Stresses of Plain 9Cr-1Mo Steel Weld Joints

NASA Astrophysics Data System (ADS)

Nagaraju, S.; Vasantharaja, P.; Brahadees, G.; Vasudevan, M.; Mahadevan, S.

2017-12-01

9Cr-1Mo steel designated as P9 is widely used in the construction of power plants and high-temperature applications. It is chosen for fabricating hexcan fuel subassembly wrapper components of fast breeder reactors. Arc welding processes are generally used for fabricating 9Cr-1Mo steel weld joints. A-TIG welding process is increasingly being adopted by the industries. In the present study, shielded metal arc (SMA), tungsten inert gas (TIG) and A-TIG welding processes are used for fabricating the 9Cr-1Mo steel weld joints of 10 mm thickness. Effect of the above welding processes on the microstructure evolution, mechanical properties and residual stresses of the weld joints has been studied in detail. All the three weld joints exhibited comparable strength and ductility values. 9Cr-1Mo steel weld joint fabricated by SMAW process exhibited lower impact toughness values caused by coarser grain size and inclusions. 9Cr-1Mo steel weld joint fabricated by TIG welding exhibited higher toughness due to finer grain size, while the weld joint fabricated by A-TIG welding process exhibited adequate toughness values. SMA steel weld joint exhibited compressive residual stresses in the weld metal and HAZ, while TIG and A-TIG weld joint exhibited tensile residual stresses in the weld metal and HAZ.

14 CFR 27.605 - Fabrication methods.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Fabrication methods. 27.605 Section 27.605... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction General § 27.605 Fabrication methods. (a) The methods of fabrication used must produce consistently sound structures. If a fabrication process (such as...

14 CFR 25.605 - Fabrication methods.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Fabrication methods. 25.605 Section 25.605... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction General § 25.605 Fabrication methods. (a) The methods of fabrication used must produce a consistently sound structure. If a fabrication process...

14 CFR 27.605 - Fabrication methods.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Fabrication methods. 27.605 Section 27.605... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction General § 27.605 Fabrication methods. (a) The methods of fabrication used must produce consistently sound structures. If a fabrication process (such as...

14 CFR 27.605 - Fabrication methods.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Fabrication methods. 27.605 Section 27.605... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction General § 27.605 Fabrication methods. (a) The methods of fabrication used must produce consistently sound structures. If a fabrication process (such as...

14 CFR 25.605 - Fabrication methods.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fabrication methods. 25.605 Section 25.605... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction General § 25.605 Fabrication methods. (a) The methods of fabrication used must produce a consistently sound structure. If a fabrication process...

14 CFR 25.605 - Fabrication methods.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Fabrication methods. 25.605 Section 25.605... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction General § 25.605 Fabrication methods. (a) The methods of fabrication used must produce a consistently sound structure. If a fabrication process...

14 CFR 27.605 - Fabrication methods.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Fabrication methods. 27.605 Section 27.605... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction General § 27.605 Fabrication methods. (a) The methods of fabrication used must produce consistently sound structures. If a fabrication process (such as...

14 CFR 25.605 - Fabrication methods.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Fabrication methods. 25.605 Section 25.605... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction General § 25.605 Fabrication methods. (a) The methods of fabrication used must produce a consistently sound structure. If a fabrication process...

14 CFR 27.605 - Fabrication methods.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fabrication methods. 27.605 Section 27.605... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction General § 27.605 Fabrication methods. (a) The methods of fabrication used must produce consistently sound structures. If a fabrication process (such as...

14 CFR 25.605 - Fabrication methods.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Fabrication methods. 25.605 Section 25.605... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction General § 25.605 Fabrication methods. (a) The methods of fabrication used must produce a consistently sound structure. If a fabrication process...

Bioinspired superhydrophobic surfaces, fabricated through simple and scalable roll-to-roll processing

PubMed Central

Park, Sung-Hoon; Lee, Sangeui; Moreira, David; Bandaru, Prabhakar R.; Han, InTaek; Yun, Dong-Jin

2015-01-01

A simple, scalable, non-lithographic, technique for fabricating durable superhydrophobic (SH) surfaces, based on the fingering instabilities associated with non-Newtonian flow and shear tearing, has been developed. The high viscosity of the nanotube/elastomer paste has been exploited for the fabrication. The fabricated SH surfaces had the appearance of bristled shark skin and were robust with respect to mechanical forces. While flow instability is regarded as adverse to roll-coating processes for fabricating uniform films, we especially use the effect to create the SH surface. Along with their durability and self-cleaning capabilities, we have demonstrated drag reduction effects of the fabricated films through dynamic flow measurements. PMID:26490133

Fabrication and evaluation of advanced titanium structural panels for supersonic cruise aircraft

NASA Technical Reports Server (NTRS)

Payne, L.

1977-01-01

Flightworthy primary structural panels were designed, fabricated, and tested to investigate two advanced fabrication methods for titanium alloys. Skin-stringer panels fabricated using the weldbraze process, and honeycomb-core sandwich panels fabricated using a diffusion bonding process, were designed to replace an existing integrally stiffened shear panel on the upper wing surface of the NASA YF-12 research aircraft. The investigation included ground testing and Mach 3 flight testing of full-scale panels, and laboratory testing of representative structural element specimens. Test results obtained on full-scale panels and structural element specimens indicate that both of the fabrication methods investigated are suitable for primary structural applications on future civil and military supersonic cruise aircraft.

Bioinspired superhydrophobic surfaces, fabricated through simple and scalable roll-to-roll processing.

PubMed

Park, Sung-Hoon; Lee, Sangeui; Moreira, David; Bandaru, Prabhakar R; Han, InTaek; Yun, Dong-Jin

2015-10-22

A simple, scalable, non-lithographic, technique for fabricating durable superhydrophobic (SH) surfaces, based on the fingering instabilities associated with non-Newtonian flow and shear tearing, has been developed. The high viscosity of the nanotube/elastomer paste has been exploited for the fabrication. The fabricated SH surfaces had the appearance of bristled shark skin and were robust with respect to mechanical forces. While flow instability is regarded as adverse to roll-coating processes for fabricating uniform films, we especially use the effect to create the SH surface. Along with their durability and self-cleaning capabilities, we have demonstrated drag reduction effects of the fabricated films through dynamic flow measurements.

Process for fabrication of cermets

DOEpatents

Landingham, Richard L [Livermore, CA

2011-02-01

Cermet comprising ceramic and metal components and a molten metal infiltration method and process for fabrication thereof. The light weight cermets having improved porosity, strength, durability, toughness, elasticity fabricated from presintered ceramic powder infiltrated with a molten metal or metal alloy. Alumina titanium cermets biocompatible with the human body suitable for bone and joint replacements.

Fabrication of Titanium Bonded Joint Specimens for High Temperature Testing

NASA Technical Reports Server (NTRS)

Smeltzer, Stanley S., III; Kovach, Michael P.; Hudson, Wanda

2005-01-01

Four sets of adhesively bonded, titanium lap-shear coupon specimens were fabricated for ultimate strength testing according to the ASTM D1002 and D3165 standards. Important features of the fabrication methods, processing details, and lap-shear test results are presented for specimens fabricated using a modified bismaleimide adhesive, EA 9673, on titanium. Surface treatment of the titanium was performed using surface abrasion followed by one of two separate chemical etching processes. Although cure cycle requirements are different among most adhesives, a single surface preparation method was sought as the preferred method for conditioning the titanium specimens prior to bonding and curing. A fabrication process using a combination of low-pressure grit-blasting of the titanium surface followed by anodization with a sodium hydroxide solution applied to the D1002 specimen geometry provided the highest lapshear strengths in the study. Additionally, difficulties documented during the fabrication process of the D3165 specimens along with features of the D3165 geometry were identified as factors that contributed to lower lap-shear strength results for the D3165 specimens as compared to the results for the D1002 specimens.

Application of N-Doped Three-Dimensional Reduced Graphene Oxide Aerogel to Thin Film Loudspeaker.

PubMed

Kim, Choong Sun; Lee, Kyung Eun; Lee, Jung-Min; Kim, Sang Ouk; Cho, Byung Jin; Choi, Jung-Woo

2016-08-31

We built a thermoacoustic loudspeaker employing N-doped three-dimensional reduced graphene oxide aerogel (N-rGOA) based on a simple template-free fabrication method. A two-step fabrication process, which includes freeze-drying and reduction/doping, was used to realize a three-dimensional, freestanding, and porous graphene-based loudspeaker, whose macroscopic structure can be easily modulated. The simplified fabrication process also allows the control of structural properties of the N-rGOAs, including density and area. Taking advantage of the facile fabrication process, we fabricated and analyzed thermoacoustic loudspeakers with different structural properties. The anlayses showed that a N-rGOA with lower density and larger area can produce a higher sound pressure level (SPL). Furthermore, the resistance of the proposed loudspeaker can be easily controlled through heteroatom doping, thereby helping to generate higher SPL per unit driving voltage. Our success in constructing an array of optimized N-rGOAs able to withstand input power as high as 40 W demonstrates that a practical thermoacoustic loudspeaker can be fabricated using the proposed mass-producible solution-based process.

Fabrication of fiber supported ionic liquids and methods of use

DOEpatents

Luebke, David R; Wickramanayake, Shan

2013-02-26

One or more embodiments relates to the production of a fabricated fiber having an asymmetric polymer network and having an immobilized liquid such as an ionic liquid within the pores of the polymer network. The process produces the fabricated fiber in a dry-wet spinning process using a homogenous dope solution, providing significant advantage over current fabrication methods for liquid-supporting polymers. The fabricated fibers may be effectively utilized for the separation of a chemical species from a mixture based on the selection of the polymer, the liquid, and the solvent utilized in the dope.

Design Architecture of field-effect transistor with back gate electrode for biosensor application

NASA Astrophysics Data System (ADS)

Fathil, M. F. M.; Arshad, M. K. Md.; Hashim, U.; Ruslinda, A. R.; Gopinath, Subash C. B.; M. Nuzaihan M., N.; Ayub, R. M.; Adzhri, R.; Zaki, M.; Azman, A. H.

2016-07-01

This paper presents the preparation method of photolithography chrome mask design used in fabrication process of field-effect transistor with back gate biasing based biosensor. Initially, the chrome masks are designed by studying the process flow of the biosensor fabrication, followed by drawing of the actual chrome mask using the AutoCAD software. The overall width and length of the device is optimized at 16 mm and 16 mm, respectively. Fabrication processes of the biosensor required five chrome masks, which included source and drain formation mask, the back gate area formation mask, electrode formation mask, front gate area formation mask, and passivation area formation mask. The complete chrome masks design will be sent for chrome mask fabrication and for future use in biosensor fabrication.

Impact of process temperature on GaSb metal-oxide-semiconductor interface properties fabricated by ex-situ process

NASA Astrophysics Data System (ADS)

Yokoyama, Masafumi; Asakura, Yuji; Yokoyama, Haruki; Takenaka, Mitsuru; Takagi, Shinichi

2014-06-01

We have studied the impact of process temperature on interface properties of GaSb metal-oxide-semiconductor (MOS) structures fabricated by an ex-situ atomic-layer-deposition (ALD) process. We have found that the ALD temperature strongly affects the Al2O3/GaSb MOS interface properties. The Al2O3/GaSb MOS interfaces fabricated at the low ALD temperature of 150 °C have the minimum interface-trap density (Dit) of ˜4.5 × 1013 cm-2 eV-1. We have also found that the post-metalization annealing at temperature higher than 200 °C degrades the Al2O3/GaSb MOS interface properties. The low-temperature process is preferable in fabricating GaSb MOS interfaces in the ex-situ ALD process to avoid the high-temperature-induced degradations.

Scattering effects of machined optical surfaces

NASA Astrophysics Data System (ADS)

Thompson, Anita Kotha

1998-09-01

Optical fabrication is one of the most labor-intensive industries in existence. Lensmakers use pitch to affix glass blanks to metal chucks that hold the glass as they grind it with tools that have not changed much in fifty years. Recent demands placed on traditional optical fabrication processes in terms of surface accuracy, smoothnesses, and cost effectiveness has resulted in the exploitation of precision machining technology to develop a new generation of computer numerically controlled (CNC) optical fabrication equipment. This new kind of precision machining process is called deterministic microgrinding. The most conspicuous feature of optical surfaces manufactured by the precision machining processes (such as single-point diamond turning or deterministic microgrinding) is the presence of residual cutting tool marks. These residual tool marks exhibit a highly structured topography of periodic azimuthal or radial deterministic marks in addition to random microroughness. These distinct topographic features give rise to surface scattering effects that can significantly degrade optical performance. In this dissertation project we investigate the scattering behavior of machined optical surfaces and their imaging characteristics. In particular, we will characterize the residual optical fabrication errors and relate the resulting scattering behavior to the tool and machine parameters in order to evaluate and improve the deterministic microgrinding process. Other desired information derived from the investigation of scattering behavior is the optical fabrication tolerances necessary to satisfy specific image quality requirements. Optical fabrication tolerances are a major cost driver for any precision optical manufacturing technology. The derivation and control of the optical fabrication tolerances necessary for different applications and operating wavelength regimes will play a unique and central role in establishing deterministic microgrinding as a preferred and a cost-effective optical fabrication process. Other well understood optical fabrication processes will also be reviewed and a performance comparison with the conventional grinding and polishing technique will be made to determine any inherent advantages in the optical quality of surfaces produced by other techniques.

Critical percolation clusters in seven dimensions and on a complete graph

NASA Astrophysics Data System (ADS)

Huang, Wei; Hou, Pengcheng; Wang, Junfeng; Ziff, Robert M.; Deng, Youjin

2018-02-01

We study critical bond percolation on a seven-dimensional hypercubic lattice with periodic boundary conditions (7D) and on the complete graph (CG) of finite volume (number of vertices) V . We numerically confirm that for both cases, the critical number density n (s ,V ) of clusters of size s obeys a scaling form n (s ,V ) ˜s-τn ˜(s /Vdf*) with identical volume fractal dimension df*=2 /3 and exponent τ =1 +1 /df*=5 /2 . We then classify occupied bonds into bridge bonds, which includes branch and junction bonds, and nonbridge bonds; a bridge bond is a branch bond if and only if its deletion produces at least one tree. Deleting branch bonds from percolation configurations produces leaf-free configurations, whereas deleting all bridge bonds leads to bridge-free configurations composed of blobs. It is shown that the fraction of nonbridge (biconnected) bonds vanishes, ρn ,CG→0 , for large CGs, but converges to a finite value, ρn ,7 D=0.006 193 1 (7 ) , for the 7D hypercube. Further, we observe that while the bridge-free dimension dbf*=1 /3 holds for both the CG and 7D cases, the volume fractal dimensions of the leaf-free clusters are different: dlf,7 D *=0.669 (9 ) ≈2 /3 and dlf,CG *=0.3337 (17 ) ≈1 /3 . On the CG and in 7D, the whole, leaf-free, and bridge-free clusters all have the shortest-path volume fractal dimension dmin*≈1 /3 , characterizing their graph diameters. We also study the behavior of the number and the size distribution of leaf-free and bridge-free clusters. For the number of clusters, we numerically find the number of leaf-free and bridge-free clusters on the CG scale as ˜lnV , while for 7D they scale as ˜V . For the size distribution, we find the behavior on the CG is governed by a modified Fisher exponent τ'=1 , while for leaf-free clusters in 7D, it is governed by Fisher exponent τ =5 /2 . The size distribution of bridge-free clusters in 7D displays two-scaling behavior with exponents τ =4 and τ'=1 . The probability distribution P (C1,V ) d C1 of the largest cluster of size C1 for whole percolation configurations is observed to follow a single-variable function P ¯(x ) d x , with x ≡C1/Vdf* for both CG and 7D. Up to a rescaling factor for the variable x , the probability functions for CG and 7D collapse on top of each other within the entire range of x . The analytical expressions in the x →0 and x →∞ limits are further confirmed. Our work demonstrates that the geometric structure of high-dimensional percolation clusters cannot be fully accounted for by their complete-graph counterparts.

Antifungal activity of fabrics knitted by metalized Silver/Polyester composite yarn

NASA Astrophysics Data System (ADS)

Özkan, İ.; Duru Baykal, P.

2017-10-01

In this study, antifungal properties of fabric knitted from metalized silver/polyester composite yarn were investigated. Intermingling is an alternative technique for yarn blending process. Yarns having different features can be combined by feeding the same intermingling jet. This process is defined as commingling. In the study, intermingling process was used to produce metalized silver/polyester composite yarn. Commingled yarns were knitted to single jersey fabrics by IPM brand sample type circular knitting machine. Antifungal activity test was applied to samples against Aspergillus Niger according to AATCC 30 test procedure. It has been identified that the application provides antifungal activity to fabric.

Improved Design of Optical MEMS Using the SUMMiT Fabrication Process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michalicek, M.A.; Comtois, J.H.; Barron, C.C.

This paper describes the design and fabrication of optical Microelectromechanical Systems (MEMS) devices using the Sandia Ultra planar Multilevel MEMS Technology (SUMMiT) fabrication process. This state of the art process, offered by Sandia National Laboratories, provides unique and very advantageous features which make it ideal for optical devices. This enabling process permits the development of micromirror devices with near ideal characteristics which have previously been unrealizable in standard polysilicon processes. This paper describes such characteristics as elevated address electrodes, individual address wiring beneath the device, planarized mirror surfaces, unique post-process metallization, and the best active surface area to date.

New prospects in pretreatment of cotton fabrics using microwave heating.

PubMed

Hashem, M; Taleb, M Abou; El-Shall, F N; Haggag, K

2014-03-15

As microwaves are known to give fast and rapid volume heating, the present study is undertaken to investigate the use of microwave heating for pretreatment cotton fabrics to reduce the pretreatment time, chemicals and water. The onset of the microwave heating technique on the physicochemical and performance properties of desized, scoured and bleached cotton fabric is elucidated and compared with those obtained on using conventional thermal heating. Combined one-step process for desizing, scouring and bleaching of cotton fabric under microwave heating was also investigated. The dual effect of adding urea, (as microwave absorber and hydrogen peroxide activator) has been exploiting to accelerate the pretreatment reaction of cotton fabric. DSC, FT-IR and SEM have been used to investigate the onset of microwave on the morphological and chemical change of cotton cellulose after pretreatment and bleaching under microwave heating. Results obtained show that, a complete fabric preparation was obtained in just 5 min on using microwave in pretreatments process and the fabric properties were comparable to those obtained in traditional pretreatment process which requires 2.5-3h for completion. Copyright © 2013 Elsevier Ltd. All rights reserved.

Fabrication of polymer electrolyte membrane fuel cell MEAs utilizing inkjet print technology

NASA Astrophysics Data System (ADS)

Towne, Silas; Viswanathan, Vish; Holbery, James; Rieke, Peter

Utilizing drop-on-demand technology, we have successfully fabricated hydrogen-air polymer electrolyte membrane fuel cells (PEMFC), demonstrated some of the processing advantages of this technology and have demonstrated that the performance is comparable to conventionally fabricated membrane electrode assemblies (MEAs). Commercial desktop inkjet printers were used to deposit the active catalyst electrode layer directly from print cartridges onto Nafion ® polymer membranes in the hydrogen form. The layers were well-adhered and withstood simple tape peel, bending and abrasion tests and did so without any post-deposition hot press step. The elimination of this processing step suggests that inkjet-based fabrication or similar processing technologies may provide a route to less expensive large-scale fabrication of PEMFCs. When tested in our experimental apparatus, open circuit voltages up to 0.87 V and power densities of up to 155 mW cm -2 were obtained with a catalyst loading of 0.20 mg Pt cm -2. A commercially available membrane under identical, albeit not optimized test conditions, showed about 7% greater power density. The objective of this work was to demonstrate some of the processing advantages of drop-on-demand technology for fabrication of MEAs. It remains to be determined if inkjet fabrication offers performance advantages or leads to more efficient utilization of expensive catalyst materials.

A sustainable and green process for scouring of cotton fabrics using xylano-pectinolytic synergism: switching from noxious chemicals to eco-friendly catalysts.

PubMed

Singh, Avtar; Kaur, Amanjot; Patra, Arun Kumar; Mahajan, Ritu

2018-04-01

The objective of this research was to develop an appropriate, eco-friendly, cost-effective bioscouring methodology for removing natural impurities from cotton fabric. Maximum bioscouring was achieved using 5.0 IU xylanase and 4.0 IU pectinase with material to liquid ratio of 1:15 in a 50 mM buffer (glycine-NaOH buffer, 1.0 mM EDTA and 1% Tween-80, pH 8.5) with a treatment time of 60 min at 50 °C and an agitation speed of 60 rpm. The bioscoured cotton fabrics showed a gain of 1.17% in whiteness, 3.23% in brightness and a reduction of 4.18% in yellowness in comparison to fabric scoured with an alkaline scouring method. Further, after bleaching, the whiteness, brightness and tensile strength of the bioscoured fabrics were increased by 2.18, 2.33 and 11.74% along with a decrease of 4.61% in yellowness of bioscoured plus bleached fabrics in comparison to chemically scoured plus bleached fabrics. From the results, it is clear that bioscouring is more efficient, energy saving and an eco-friendly process and has the potential to replace the environment-damaging scouring process with the xylano-pectinolytic bioscouring process.

Hydrogen ion microlithography

DOEpatents

Tsuo, Y. Simon; Deb, Satyen K.

1990-01-01

Disclosed is a hydrogen ion microlithography process for use in microelectronic fabrication and semiconductor device processing. The process comprises the steps of providing a single layer of either an amorphous silicon or hydrogenated amorphous silicon material. A pattern is recorded in a selected layer of amorphous silicon or hydrogenated amorphous silicon materials by preferentially implanting hydrogen ions therein so as to permit the selected layer to serve as a mask-resist wafer suitable for subsequent development and device fabrication. The layer is developed to provide a surface pattern therein adaptable for subsequent use in microelectronic fabrication and semiconductor device processing.

3D MEMS in Standard Processes: Fabrication, Quality Assurance, and Novel Measurement Microstructures

NASA Technical Reports Server (NTRS)

Lin, Gisela; Lawton, Russell A.

2000-01-01

Three-dimensional MEMS microsystems that are commercially fabricated require minimal post-processing and are easily integrated with CMOS signal processing electronics. Measurements to evaluate the fabrication process (such as cross-sectional imaging and device performance characterization) provide much needed feedback in terms of reliability and quality assurance. MEMS technology is bringing a new class of microscale measurements to fruition. The relatively small size of MEMS microsystems offers the potential for higher fidelity recordings compared to macrosize counterparts, as illustrated in the measurement of muscle cell forces.

Fabrication and Characterization of High Strength Al-Cu Alloys Processed Using Laser Beam Melting in Metal Powder Bed

NASA Astrophysics Data System (ADS)

Ahuja, Bhrigu; Karg, Michael; Nagulin, Konstantin Yu.; Schmidt, Michael

The proposed paper illustrates fabrication and characterization of high strength Aluminium Copper alloys processed using Laser Beam Melting process. Al-Cu alloys EN AW-2219 and EN AW-2618 are classified as wrought alloys and 2618 is typically considered difficult to weld. Laser Beam Melting (LBM) process from the family of Additive Manufacturing processes, has the unique ability to form fully dense complex 3D geometries using micro sized metallic powder in a layer by layer fabrication methodology. LBM process can most closely be associated to the conventional laser welding process, but has significant differences in terms of the typical laser intensities and scan speeds used. Due to the use of high intensities and fast scan speeds, the process induces extremely high heating and cooling rates. This property gives it a unique physical attribute and therefore its ability to process high strength Al-Cu alloys needs to be investigated. Experiments conducted during the investigations associate the induced energy density controlled by varying process parameters to the achieved relative densities of the fabricated 3D structures.

A Theoretical Model for Predicting Residual Stress Generation in Fabrication Process of Double-Ceramic-Layer Thermal Barrier Coating System.

PubMed

Song, Yan; Wu, Weijie; Xie, Feng; Liu, Yilun; Wang, Tiejun

2017-01-01

Residual stress arisen in fabrication process of Double-Ceramic-Layer Thermal Barrier Coating System (DCL-TBCs) has a significant effect on its quality and reliability. In this work, based on the practical fabrication process of DCL-TBCs and the force and moment equilibrium, a theoretical model was proposed at first to predict residual stress generation in its fabrication process, in which the temperature dependent material properties of DCL-TBCs were incorporated. Then, a Finite Element method (FEM) has been carried out to verify our theoretical model. Afterwards, some important geometric parameters for DCL-TBCs, such as the thickness ratio of stabilized Zirconia (YSZ, ZrO2-8%Y2O3) layer to Lanthanum Zirconate (LZ, La2Zr2O7) layer, which is adjustable in a wide range in the fabrication process, have a remarkable effect on its performance, therefore, the effect of this thickness ratio on residual stress generation in the fabrication process of DCL-TBCs has been systematically studied. In addition, some thermal spray treatment, such as the pre-heating treatment, its effect on residual stress generation has also been studied in this work. It is found that, the final residual stress mainly comes from the cooling down process in the fabrication of DCL-TBCs. Increasing the pre-heating temperature can obviously decrease the magnitude of residual stresses in LZ layer, YSZ layer and substrate. With the increase of the thickness ratio of YSZ layer to LZ layer, magnitudes of residual stresses arisen in LZ layer and YSZ layer will increase while residual stress in substrate will decrease.

A Theoretical Model for Predicting Residual Stress Generation in Fabrication Process of Double-Ceramic-Layer Thermal Barrier Coating System

PubMed Central

Song, Yan; Wu, Weijie; Xie, Feng; Liu, Yilun; Wang, Tiejun

2017-01-01

Residual stress arisen in fabrication process of Double-Ceramic-Layer Thermal Barrier Coating System (DCL-TBCs) has a significant effect on its quality and reliability. In this work, based on the practical fabrication process of DCL-TBCs and the force and moment equilibrium, a theoretical model was proposed at first to predict residual stress generation in its fabrication process, in which the temperature dependent material properties of DCL-TBCs were incorporated. Then, a Finite Element method (FEM) has been carried out to verify our theoretical model. Afterwards, some important geometric parameters for DCL-TBCs, such as the thickness ratio of stabilized Zirconia (YSZ, ZrO2-8%Y2O3) layer to Lanthanum Zirconate (LZ, La2Zr2O7) layer, which is adjustable in a wide range in the fabrication process, have a remarkable effect on its performance, therefore, the effect of this thickness ratio on residual stress generation in the fabrication process of DCL-TBCs has been systematically studied. In addition, some thermal spray treatment, such as the pre-heating treatment, its effect on residual stress generation has also been studied in this work. It is found that, the final residual stress mainly comes from the cooling down process in the fabrication of DCL-TBCs. Increasing the pre-heating temperature can obviously decrease the magnitude of residual stresses in LZ layer, YSZ layer and substrate. With the increase of the thickness ratio of YSZ layer to LZ layer, magnitudes of residual stresses arisen in LZ layer and YSZ layer will increase while residual stress in substrate will decrease. PMID:28103275

Composite Structures and Materials Research at NASA Langley Research Center

NASA Technical Reports Server (NTRS)

Starnes, James H., Jr.; Dexter, H. Benson; Johnston, Norman J.; Ambur, Damodar R.; Cano, roberto J.

2003-01-01

A summary of recent composite structures and materials research at NASA Langley Research Center is presented. Fabrication research to develop low-cost automated robotic fabrication procedures for thermosetting and thermoplastic composite materials, and low-cost liquid molding processes for preformed textile materials is described. Robotic fabrication procedures discussed include ply-by-ply, cure-on-the-fly heated placement head and out-of-autoclave electron-beam cure methods for tow and tape thermosetting and thermoplastic materials. Liquid molding fabrication processes described include Resin Film Infusion (RFI), Resin Transfer Molding (RTM) and Vacuum-Assisted Resin Transfer Molding (VARTM). Results for a full-scale composite wing box are summarized to identify the performance of materials and structures fabricated with these low-cost fabrication methods.

Composite Structures and Materials Research at NASA Langley Research Center

NASA Technical Reports Server (NTRS)

Starnes, James H., Jr.; Dexter, H. Benson; Johnston, Norman J.; Ambur, Damodar R.; Cano, Roberto J.

2001-01-01

A summary of recent composite structures and materials research at NASA Langley Research Center is presented. Fabrication research to develop low-cost automated robotic fabrication procedures for thermosetting and thermoplastic composite materials, and low-cost liquid molding processes for preformed textile materials is described. Robotic fabrication procedures discussed include ply-by-ply, cure-on-the-fly heated placement head and out-of-autoclave electron-beam cure methods for tow and tape thermosetting and thermoplastic materials. Liquid molding fabrication processes described include Resin Film Infusion (RFI) Resin Transfer Molding (RTM) and Vacuum-Assisted Resin Transfer Molding (VARTM). Results for a full-scale composite wing box are summarized to identify the performance of materials and structures fabricated with these low-cost fabrication methods.

The role of rapid solidification processing in the fabrication of fiber reinforced metal matrix composites

NASA Technical Reports Server (NTRS)

Locci, Ivan E.; Noebe, Ronald D.

1989-01-01

Advanced composite processing techniques for fiber reinforced metal matrix composites require the flexibility to meet several widespread objectives. The development of uniquely desired matrix microstructures and uniformly arrayed fiber spacing with sufficient bonding between fiber and matrix to transmit load between them without degradation to the fiber or matrix are the minimum requirements necessary of any fabrication process. For most applications these criteria can be met by fabricating composite monotapes which are then consolidated into composite panels or more complicated components such as fiber reinforced turbine blades. Regardless of the end component, composite monotapes are the building blocks from which near net shape composite structures can be formed. The most common methods for forming composite monotapes are the powder cloth, foil/fiber, plasma spray, and arc spray processes. These practices, however, employ rapid solidification techniques in processing of the composite matrix phase. Consequently, rapid solidification processes play a vital and yet generally overlooked role in composite fabrication. The future potential of rapid solidification processing is discussed.

Stretchable electronics for wearable and high-current applications

NASA Astrophysics Data System (ADS)

Hilbich, Daniel; Shannon, Lesley; Gray, Bonnie L.

2016-04-01

Advances in the development of novel materials and fabrication processes are resulting in an increased number of flexible and stretchable electronics applications. This evolving technology enables new devices that are not readily fabricated using traditional silicon processes, and has the potential to transform many industries, including personalized healthcare, consumer electronics, and communication. Fabrication of stretchable devices is typically achieved through the use of stretchable polymer-based conductors, or more rigid conductors, such as metals, with patterned geometries that can accommodate stretching. Although the application space for stretchable electronics is extensive, the practicality of these devices can be severely limited by power consumption and cost. Moreover, strict process flows can impede innovation that would otherwise enable new applications. In an effort to overcome these impediments, we present two modified approaches and applications based on a newly developed process for stretchable and flexible electronics fabrication. This includes the development of a metallization pattern stamping process allowing for 1) stretchable interconnects to be directly integrated with stretchable/wearable fabrics, and 2) a process variation enabling aligned multi-layer devices with integrated ferromagnetic nanocomposite polymer components enabling a fully-flexible electromagnetic microactuator for large-magnitude magnetic field generation. The wearable interconnects are measured, showing high conductivity, and can accommodate over 20% strain before experiencing conductive failure. The electromagnetic actuators have been fabricated and initial measurements show well-aligned, highly conductive, isolated metal layers. These two applications demonstrate the versatility of the newly developed process and suggest potential for its furthered use in stretchable electronics and MEMS applications.

Printing-based fabrication method using sacrificial paper substrates for flexible and wearable microfluidic devices

NASA Astrophysics Data System (ADS)

Chung, Daehan; Gray, Bonnie L.

2017-11-01

We present a simple, fast, and inexpensive new printing-based fabrication process for flexible and wearable microfluidic channels and devices. Microfluidic devices are fabricated on textiles (fabric) for applications in clothing-based wearable microfluidic sensors and systems. The wearable and flexible microfluidic devices are comprised of water-insoluable screen-printable plastisol polymer. Sheets of paper are used as sacrificial substrates for multiple layers of polymer on the fabric’s surface. Microfluidic devices can be made within a short time using simple processes and inexpensive equipment that includes a laser cutter and a thermal laminator. The fabrication process is characterized to demonstrate control of microfluidic channel thickness and width. Film thickness smaller than 100 micrometers and lateral dimensions smaller than 150 micrometers are demonstrated. A flexible microfluidic mixer is also developed on fabric and successfully tested on both flat and curved surfaces at volumetric flow rates ranging from 5.5-46 ml min-1.

Fabrication of PDMS through-holes using the MIMIC method and the surface treatment by atmospheric-pressure CH4/He RF plasma

NASA Astrophysics Data System (ADS)

Choi, Jongchan; Lee, Kyeong-Hwan; Yang, Sung

2011-09-01

This note presents a simple fabrication process for patterning micro through-holes in a PDMS layer by a combination of the micromolding in capillaries (MIMIC) method and the surface treatment by atmospheric-pressure CH4/He RF plasma. The fabrication process is confirmed by forming micro through-holes with various shapes including circle, C-shape, open microfluidic channel and hemisphere. All micro through-holes of various shapes in a wide range of diameters and heights are well fabricated by the proposed method. Also, a 3D micromixer containing a PDMS micro through-hole layer formed by the proposed method is built and its performance is tested as another practical demonstration of the proposed fabrication method. Therefore, we believe that the proposed fabrication process will build a PDMS micro through-hole layer in a simple and easy way and will contribute to developing highly efficient multi-layered microfluidic systems, which may require PDMS micro through-hole layers.

Processing and Characterization of Peti Composites Fabricated by High Temperature Vartm (Section)

NASA Technical Reports Server (NTRS)

Ghose, Sayata; Cano, Roberto J.; Watson, Kent A.; Britton, Sean M.; Jensen, Brian J.; Connell, John W.; Smith, Joseph G., Jr.; Loos, Alfred C.; Heider, Dirk

2011-01-01

The use of composites as primary structures on aerospace vehicles has increased dramatically over the past decade, but so have the production costs associated with their fabrication. For certain composites, high temperature vacuum assisted resin transfer molding (HT-VARTM) can offer reduced fabrication costs compared to conventional autoclave techniques. The process has been successfully used with phenylethynyl terminated imide (PETI) resins developed by NASA Langley Research Center (LaRC). In the current study, three PETI resins have been used to make test specimens using HT-VARTM. Based on previous work at NASA LaRC, larger panels with a quasi-isotropic lay-up were fabricated. The resultant composite specimens exhibited void contents of 3% by volume depending on the type of carbon fabric preform used. Mechanical properties of the panels were determined at both room and elevated temperatures. Fabric permeability characterizations and limited process modeling efforts were carried out to determine infusion times and composite panel size limitations. In addition, new PETI based resins were synthesized specifically for HT-VARTM.

Fabrication of Mechanically Tunable and Bioactive Metal Scaffolds for Biomedical Applications

PubMed Central

Jung, Hyun-Do; Lee, Hyun; Kim, Hyoun-Ee; Koh, Young-Hag; Song, Juha

2015-01-01

Biometal systems have been widely used for biomedical applications, in particular, as load-bearing materials. However, major challenges are high stiffness and low bioactivity of metals. In this study, we have developed a new method towards fabricating a new type of bioactive and mechanically reliable porous metal scaffolds-densified porous Ti scaffolds. The method consists of two fabrication processes, 1) the fabrication of porous Ti scaffolds by dynamic freeze casting, and 2) coating and densification of the porous scaffolds. The dynamic freeze casting method to fabricate porous Ti scaffolds allowed the densification of porous scaffolds by minimizing the chemical contamination and structural defects. The densification process is distinctive for three reasons. First, the densification process is simple, because it requires a control of only one parameter (degree of densification). Second, it is effective, as it achieves mechanical enhancement and sustainable release of biomolecules from porous scaffolds. Third, it has broad applications, as it is also applicable to the fabrication of functionally graded porous scaffolds by spatially varied strain during densification. PMID:26709604

Fabrication of tunable diffraction grating by imprint lithography with photoresist mold

NASA Astrophysics Data System (ADS)

Yamada, Itsunari; Ikeda, Yusuke; Higuchi, Tetsuya

2018-05-01

We fabricated a deformable transmission silicone [poly(dimethylsiloxane)] grating using a two-beam interference method and imprint lithography and evaluated its optical characteristics during a compression process. The grating pattern with 0.43 μm depth and 1.0 μm pitch was created on a silicone surface by an imprinting process with a photoresist mold to realize a simple, low-cost fabrication process. The first-order diffraction transmittance of this grating reached 10.3% at 632.8 nm wavelength. We also measured the relationship between the grating period and compressive stress to the fabricated elements. The grating period changed from 1.0 μm to 0.84 μm by 16.6% compression of the fabricated element in one direction, perpendicular to the grooves, and the first-order diffraction transmittance was 8.6%.

Automated Tow Placement Processing and Characterization of Composites

NASA Technical Reports Server (NTRS)

Prabhakaran, R.

2004-01-01

The project had one of the initial objectives as automated tow placement (ATP), in which a robot was used to place a collimated band of pre-impregnated ribbons or a wide preconsolidated tape onto a tool surface. It was proposed to utilize the Automated Tow Placement machine that was already available and to fabricate carbon fiber reinforced PEEK (polyether-ether-ketone) matrix composites. After initial experiments with the fabrication of flat plates, composite cylinders were to be fabricated. Specimens from the fabricated parts were to be tested for mechanical characterization. A second objective was to conduct various types of tests for characterizing composite specimens cured by different fabrication processes.

Fabrication and characterization of resonant SOI micromechanical silicon sensors based on DRIE micromachining, freestanding release process and silicon direct bonding

NASA Astrophysics Data System (ADS)

Gigan, Olivier; Chen, Hua; Robert, Olivier; Renard, Stephane; Marty, Frederic

2002-11-01

This paper is dedicated to the fabrication and technological aspect of a silicon microresonator sensor. The entire project includes the fabrication processes, the system modelling/simulation, and the electronic interface. The mechanical model of such resonator is presented including description of frequency stability and Hysterises behaviour of the electrostatically driven resonator. Numeric model and FEM simulations are used to simulate the system dynamic behaviour. The complete fabrication process is based on standard microelectronics technology with specific MEMS technological steps. The key steps are described: micromachining on SOI by Deep Reactive Ion Etching (DRIE), specific release processes to prevent sticking (resist and HF-vapour release process) and collective vacuum encapsulation by Silicon Direct Bonding (SDB). The complete process has been validated and prototypes have been fabricated. The ASIC was designed to interface the sensor and to control the vibration amplitude. This electronic was simulated and designed to work up to 200°C and implemented in a standard 0.6μ CMOS technology. Characterizations of sensor prototypes are done both mechanically and electrostatically. These measurements showed good agreements with theory and FEM simulations.

INDUSTRIE 4.0 - Automation in weft knitting technology

NASA Astrophysics Data System (ADS)

Simonis, K.; Gloy, Y.-S.; Gries, T.

2016-07-01

Industry 4.0 applies to the knitting industry. Regarding the knitting process retrofitting activities are executed mostly manually by an operator on the basis on the operator's experience. In doing so, the knitted fabric is not necessarily produced in the most efficient way regarding process speed and fabric quality aspects. The knitting division at ITA is concentrating on project activities regarding automation and Industry 4.0. ITA is working on analysing the correspondences of the knitting process parameters and their influence on the fabric quality. By using e.g. the augmented reality technology, the operator will be supported when setting up the knitting machine in case of product or pattern change - or in case of an intervention when production errors occur. Furthermore, the RFID-Technology offers great possibilities to ensure information flow between sub-processes of the fragmented textile process chain. ITA is using RFID-chips to save yarn production information and connect the information to the fabric producing machine control. In addition, ITA is currently working on integrating image processing systems into the large circular knitting machine in order to ensure online-quality measurement of the knitted fabrics. This will lead to a self-optimizing and selflearning knitting machine.

Route to one-step microstructure mold fabrication for PDMS microfluidic chip

NASA Astrophysics Data System (ADS)

Lv, Xiaoqing; Geng, Zhaoxin; Fan, Zhiyuan; Wang, Shicai; Su, Yue; Fang, Weihao; Pei, Weihua; Chen, Hongda

2018-04-01

The microstructure mold fabrication for PDMS microfluidic chip remains complex and time-consuming process requiring special equipment and protocols: photolithography and etching. Thus, a rapid and cost-effective method is highly needed. Comparing with the traditional microfluidic chip fabricating process based on the micro-electromechanical system (MEMS), this method is simple and easy to implement, and the whole fabrication process only requires 1-2 h. Different size of microstructure from 100 to 1000 μm was fabricated, and used to culture four kinds of breast cancer cell lines. Cell viability and morphology was assessed when they were cultured in the micro straight channels, micro square holes and the bonding PDMS-glass microfluidic chip. The experimental results indicate that the microfluidic chip is good and meet the experimental requirements. This method can greatly reduce the process time and cost of the microfluidic chip, and provide a simple and effective way for the structure design and in the field of biological microfabrications and microfluidic chips.

Single-Run Single-Mask Inductively-Coupled-Plasma Reactive-Ion-Etching Process for Fabricating Suspended High-Aspect-Ratio Microstructures

NASA Astrophysics Data System (ADS)

Yang, Yao-Joe; Kuo, Wen-Cheng; Fan, Kuang-Chao

2006-01-01

In this work, we present a single-run single-mask (SRM) process for fabricating suspended high-aspect-ratio structures on standard silicon wafers using an inductively coupled plasma-reactive ion etching (ICP-RIE) etcher. This process eliminates extra fabrication steps which are required for structure release after trench etching. Released microstructures with 120 μm thickness are obtained by this process. The corresponding maximum aspect ratio of the trench is 28. The SRM process is an extended version of the standard process proposed by BOSCH GmbH (BOSCH process). The first step of the SRM process is a standard BOSCH process for trench etching, then a polymer layer is deposited on trench sidewalls as a protective layer for the subsequent structure-releasing step. The structure is released by dry isotropic etching after the polymer layer on the trench floor is removed. All the steps can be integrated into a single-run ICP process. Also, only one mask is required. Therefore, the process complexity and fabrication cost can be effectively reduced. Discussions on each SRM step and considerations for avoiding undesired etching of the silicon structures during the release process are also presented.

A Self-Aligned a-IGZO Thin-Film Transistor Using a New Two-Photo-Mask Process with a Continuous Etching Scheme.

PubMed

Fan, Ching-Lin; Shang, Ming-Chi; Li, Bo-Jyun; Lin, Yu-Zuo; Wang, Shea-Jue; Lee, Win-Der

2014-08-11

Minimizing the parasitic capacitance and the number of photo-masks can improve operational speed and reduce fabrication costs. Therefore, in this study, a new two-photo-mask process is proposed that exhibits a self-aligned structure without an etching-stop layer. Combining the backside-ultraviolet (BUV) exposure and backside-lift-off (BLO) schemes can not only prevent the damage when etching the source/drain (S/D) electrodes but also reduce the number of photo-masks required during fabrication and minimize the parasitic capacitance with the decreasing of gate overlap length at same time. Compared with traditional fabrication processes, the proposed process yields that thin-film transistors (TFTs) exhibit comparable field-effect mobility (9.5 cm²/V·s), threshold voltage (3.39 V), and subthreshold swing (0.3 V/decade). The delay time of an inverter fabricated using the proposed process was considerably decreased.

A Self-Aligned a-IGZO Thin-Film Transistor Using a New Two-Photo-Mask Process with a Continuous Etching Scheme

PubMed Central

Fan, Ching-Lin; Shang, Ming-Chi; Li, Bo-Jyun; Lin, Yu-Zuo; Wang, Shea-Jue; Lee, Win-Der

2014-01-01

Minimizing the parasitic capacitance and the number of photo-masks can improve operational speed and reduce fabrication costs. Therefore, in this study, a new two-photo-mask process is proposed that exhibits a self-aligned structure without an etching-stop layer. Combining the backside-ultraviolet (BUV) exposure and backside-lift-off (BLO) schemes can not only prevent the damage when etching the source/drain (S/D) electrodes but also reduce the number of photo-masks required during fabrication and minimize the parasitic capacitance with the decreasing of gate overlap length at same time. Compared with traditional fabrication processes, the proposed process yields that thin-film transistors (TFTs) exhibit comparable field-effect mobility (9.5 cm2/V·s), threshold voltage (3.39 V), and subthreshold swing (0.3 V/decade). The delay time of an inverter fabricated using the proposed process was considerably decreased. PMID:28788159

Phase 2 of the array automated assembly task for the low cost solar array project

NASA Technical Reports Server (NTRS)

Campbell, R. B.; Davis, J. R.; Ostroski, J. W.; Rai-Choudhury, P.; Rohatgi, A.; Seman, E. J.; Stapleton, R. E.

1979-01-01

The process sequence for the fabrication of dendritic web silicon into solar panels was modified to include aluminum back surface field formation. Plasma etching was found to be a feasible technique for pre-diffusion cleaning of the web. Several contacting systems were studied. The total plated Pd-Ni system was not compatible with the process sequence; however, the evaporated TiPd-electroplated Cu system was shown stable under life testing. Ultrasonic bonding parameters were determined for various interconnect and contact metals but the yield of the process was not sufficiently high to use for module fabrication at this time. Over 400 solar cells were fabricated according to the modified sequence. No sub-process incompatibility was seen. These cells were used to fabricate four demonstration modules. A cost analysis of the modified process sequence resulted in a selling price of $0.75/peak watt.

Fabrication of GRCop-84 Rocket Thrust Chambers

NASA Technical Reports Server (NTRS)

Loewenthal, William; Ellis, David

2006-01-01

GRCop-84, a copper alloy, Cu-8 at% Cr-4 at% Nb developed at NASA Glenn Research Center for regenerative1y cooled rocket engine liners has excellent combinations of elevated temperature strength, creep resistance, thermal conductivity and low cycle fatigue. GRCop-84 is produced from pre-alloyed atomized powder and has been fabricated into plate, sheet and tube forms as well as near net shapes. Fabrication processes to produce demonstration rocket combustion chambers will be presented and includes powder production, extruding, rolling, forming, friction stir welding, and metal spinning. GRCop-84 has excellent workability and can be readily fabricated into complex components using conventional powder and wrought metallurgy processes. Rolling was examined in detail for process sensitivity at various levels of total reduction, rolling speed and rolling temperature representing extremes of commercial processing conditions. Results indicate that process conditions can range over reasonable levels without any negative impact to properties.

Fabrication of GRCop-84 Rocket Thrust Chambers

NASA Technical Reports Server (NTRS)

Loewenthal, William S.; Ellis, David L.

2005-01-01

GRCop-84, a copper alloy, Cu-8 at% Cr-4 at% Nb developed at NASA Glenn Research Center for regeneratively cooled rocket engine liners has excellent combinations of elevated temperature strength, creep resistance, thermal conductivity and low cycle fatigue. GRCop-84 is produced from prealloyed atomized powder and has been fabricated into plate, sheet and tube forms as well as near net shapes. Fabrication processes to produce demonstration rocket combustion chambers will be presented and includes powder production, extruding, rolling, forming, friction stir welding, and metal spinning. GRCop-84 has excellent workability and can be readily fabricated into complex components using conventional powder and wrought metallurgy processes. Rolling was examined in detail for process sensitivity at various levels of total reduction, rolling speed and rolling temperature representing extremes of commercial processing conditions. Results indicate that process conditions can range over reasonable levels without any negative impact to properties.

Design and fabrication of MEMS devices using the integration of MUMPs, trench-refilled molding, DRIE and bulk silicon etching processes

NASA Astrophysics Data System (ADS)

Wu, Mingching; Fang, Weileun

2005-03-01

This work integrates multi-depth DRIE etching, trench-refilled molding, two poly-Si layers MUMPs and bulk releasing to improve the variety and performance of MEMS devices. In summary, the present fabrication process, named MOSBE II, has three merits. First, this process can monolithically fabricate and integrate poly-Si thin-film structures with different thicknesses and stiffnesses, such as the flexible spring and the stiff mirror plate. Second, multi-depth structures, such as vertical comb electrodes, are available from the DRIE processes. Third, a cavity under the micromachined device is provided by the bulk silicon etching process, so that a large out-of-plane motion is allowed. In application, an optical scanner driven by the self-aligned vertical comb actuator was demonstrated. The poly-Si micromachined components fabricated by MOSBE II can further integrate with the MUMPs devices to establish a more powerful MOEMS platform.

Ion traps fabricated in a CMOS foundry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehta, K. K.; Ram, R. J.; Eltony, A. M.

2014-07-28

We demonstrate trapping in a surface-electrode ion trap fabricated in a 90-nm CMOS (complementary metal-oxide-semiconductor) foundry process utilizing the top metal layer of the process for the trap electrodes. The process includes doped active regions and metal interconnect layers, allowing for co-fabrication of standard CMOS circuitry as well as devices for optical control and measurement. With one of the interconnect layers defining a ground plane between the trap electrode layer and the p-type doped silicon substrate, ion loading is robust and trapping is stable. We measure a motional heating rate comparable to those seen in surface-electrode traps of similar size.more » This demonstration of scalable quantum computing hardware utilizing a commercial CMOS process opens the door to integration and co-fabrication of electronics and photonics for large-scale quantum processing in trapped-ion arrays.« less

Design for producing fiberglass fabric in a lunar environment

NASA Technical Reports Server (NTRS)

Benson, Rafer M.; Causby, Dana R.; Johnson, Michael C.; Storey, Mark A.; Tran, Dal T.; Zahr, Thomas A.

1992-01-01

The purpose of this project was to design a method of producing a fabric material on the lunar surface from readily available glass fibers. Various methods for forming fabrics were analyzed to determine which methods were appropriate for the lunar conditions. A nonwoven process was determined to be the most suitable process for making a fabric material out of fiberglass under these conditions. Various resins were considered for adhering the fibers. A single thermoplastic resin (AURUM) was found to be the only applicable resin. The end product of the process was determined to be suitable for use as a roadway surfacing material, canopy material, reflective material, or packaging material. A cost analysis of the lunar process versus shipping the end-product from the Earth suggests that the lunar formation is highly feasible. A design for a lunar, nonwoven process was determined and is included.

Design for producing fiberglass fabric in a lunar environment

NASA Technical Reports Server (NTRS)

Dorrity, J. Lewis; Patel, Suneer; Benson, Rafer M.; Johnson, Michael C.; Storey, Mark A.; Tran, Dai T.; Zahr, Thomas A.; Causby, Dana R.

1992-01-01

The purpose of this project was to design a method of producing a fabric material on the lunar surface from readily available glass fibers. Various methods for forming fabrics were analyzed to determine which methods were appropriate for the lunar conditions. A nonwoven process was determined to be the most suitable process for making a fabric material out of fiberglass under these conditions. Various resins were considered for adhering the fibers. A single thermoplastic resin (AURUM) was found to be the only applicable resin. The end product of the process was determined to be suitable for use as a roadway surfacing material, canopy materials, reflective material, or packaging material. A cost analysis of the lunar process versus shipping the end-product from the earth suggests that the lunar formation is highly feasible. A design for a lunar, nonwoven process was determined and included in the following document.

Fabrication of rectangular cross-sectional microchannels on PMMA with a CO2 laser and underwater fabricated copper mask

NASA Astrophysics Data System (ADS)

Prakash, Shashi; Kumar, Subrata

2017-09-01

CO2 lasers are commonly used for fabricating polymer based microfluidic devices. Despite several key advantages like low cost, time effectiveness, easy to operate and no requirement of clean room facility, CO2 lasers suffer from few disadvantages like thermal bulging, improper dimensional control, difficulty to produce microchannels of other than Gaussian cross sectional shapes and inclined surface walls. Many microfluidic devices require square or rectangular cross-sections which are difficult to produce using normal CO2 laser procedures. In this work, a thin copper sheet of 40 μm was used as a mask above the PMMA (Polymethyl-methacrylate) substrate while fabricating the microchannels utilizing the raster scanning feature of the CO2 lasers. Microchannels with different width dimensions were fabricated utilizing a CO2 laser in with mask and without-mask conditions. A comparison of both the fabricating process has been made. It was found that microchannels with U shape cross section and rectangular cross-section can efficiently be produced using the with mask technique. In addition to this, this technique can provide perfect dimensional control and better surface quality of the microchannel walls. Such a microchannel fabrication process do not require any post-processing. The fabrication of mask using a nanosecond fiber laser has been discussed in details. An underwater laser fabrication method was adopted to overcome heat related defects in mask preparation. Overall, the technique was found to be easy to adopt and significant improvements were observed in microchannel fabrication.

Fabrication of Thermoplastic Composite Laminates Having Film Interleaves By Automated Fiber Placement

NASA Technical Reports Server (NTRS)

Hulcher, A. B.; Tiwari, S. N.; Marchello, J. M.; Johnston, Norman J. (Technical Monitor)

2001-01-01

Experiments were carried out at the NASA Langley Research Center automated Fiber placement facility to determine an optimal process for the fabrication of composite materials having polymer film interleaves. A series of experiments was conducted to determine an optimal process for the composite prior to investigation of a process to fabricate laminates with polymer films. The results of the composite tests indicated that a well-consolidated, void-free laminate could be attained. Preliminary interleaf processing trials were then conducted to establish some broad guidelines for film processing. The primary finding of these initial studies was that a two-stage process was necessary in order to process these materials adequately. A screening experiment was then performed to determine the relative influence of the process variables on the quality of the film interface as determined by the wedge peel test method. Parameters that were found to be of minor influence on specimen quality were subsequently held at fixed values enabling a more rapid determination of an optimal process. Optimization studies were then performed by varying the remaining parameters at three film melt processing rates. The resulting peel data were fitted with quadratic response surfaces. Additional specimens were fabricated at levels of high peel strength as predicted by the regression models in an attempt to gage the accuracy of the predicted response and to assess the repeatability of the process. The overall results indicate that quality laminates having film interleaves can be successfully and repeatably fabricated by automated fiber placement.

An infiltration/cure model for manufacture of fabric composites by the resin infusion process

NASA Technical Reports Server (NTRS)

Weideman, Mark H.; Loos, Alfred C.; Dexter, H. Benson; Hasko, Gregory H.

1992-01-01

A 1-D infiltration/cure model was developed to simulate fabrication of advanced textile composites by the resin film infusion process. The simulation model relates the applied temperature and pressure processing cycles, along with the experimentally measured compaction and permeability characteristics of the fabric preforms, to the temperature distribution, the resin degree of cure and viscosity, and the infiltration flow front position as a function of time. The model also predicts the final panel thickness, fiber volume fraction, and resin mass for full saturation as a function of compaction pressure. Composite panels were fabricated using the RTM (Resin Transfer Molding) film infusion technique from knitted, knitted/stitched, and 2-D woven carbon preforms and Hercules 3501-6 resin. Fabric composites were fabricated at different compaction pressures and temperature cycles to determine the effects of the processing on the properties. The composites were C-scanned and micrographed to determine the quality of each panel. Advanced cure cycles, developed from the RTM simulation model, were used to reduce the total cure cycle times by a factor of 3 and the total infiltration times by a factor of 2.

Computer Aided Process Planning (CAPP): The User Interface for the Fabrication Module of the Rapid Design System

DTIC Science & Technology

1991-01-01

plan. The Fabrication Planning Module automatically creates a plan using information from the Feature Based Design Environment (FBDE) of the RDS. It...llll By using the user Interface, the final process plan can be modified in many different ways. The translation of a design feature to a more...for the review and modification of a process plan. The Fabrication Planning Module automatically creates a plan using information from the Feature Based

Development and fabrication of a solar cell junction processing system

NASA Technical Reports Server (NTRS)

Bunker, S.

1981-01-01

A solar cell junction processing system was developed and fabricated. A pulsed electron beam for the four inch wafers is being assembled and tested, wafers were successfully pulsed, and solar cells fabricated. Assembly of the transport locks is completed. The transport was operated successfully but not with sufficient reproducibility. An experiment test facility to examine potential scaleup problems associated with the proposed ion implanter design was constructed and operated. Cells were implanted and found to have efficiency identical to the normal Spire implant process.

A simple method for fabricating microwire tetrode with sufficient rigidity and integrity without a heat-fusing process.

PubMed

Liao, Yi-Fang; Tsai, Meng-Li; Yen, Chen-Tung; Cheng, Chiung-Hsiang

2011-02-15

Heat-fusing is a common process for fabricating microwire tetrodes. However, it is time-consuming, and the high-temperature treatment can easily cause the insulation of the microwire to overheat leading to short circuits. We herein provide a simple, fast method to fabricate microwire tetrodes without the heat-fusion process. By increasing the twisting density, we were able to fabricate tetrodes with good rigidity and integrity. This kind of tetrode showed good recording quality, penetrated the brain surface easily, and remained intact after chronic implantation. This method requires only general laboratory tools and is relatively simple even for inexperienced workers. © 2010 Elsevier B.V. All rights reserved.

Robust and durable superhydrophobic cotton fabrics for oil/water separation.

PubMed

Zhou, Xiaoyan; Zhang, Zhaozhu; Xu, Xianghui; Guo, Fang; Zhu, Xiaotao; Men, Xuehu; Ge, Bo

2013-08-14

By introducing the incorporation of polyaniline and fluorinated alkyl silane to the cotton fabric via a facile vapor phase deposition process, the fabric surface possessed superhydrophobicity with the water contact angle of 156° and superoleophilicity with the oil contact angle of 0°. The as-prepared fabric can be applied as effective materials for the separation of water and oil mixture with separation efficiency as high as 97.8%. Compared with other materials for oil/water separation, the reported process was simple, time-saving, and repeatable for at least 30 times. Moreover, the obtained fabric kept stable superhydrophobicity and high separation efficiency under extreme environment conditions of high temperature, high humidity, strong acidic or alkaline solutions, and mechanical forces. Therefore, this reported fabric has the advantages of scalable fabrication, high separation efficiency, stable recyclability, and excellent durability, exhibiting the strong potential for industrial production.

Hydrogen ion microlithography

DOEpatents

Tsuo, Y.S.; Deb, S.K.

1990-10-02

Disclosed is a hydrogen ion microlithography process for use in microelectronic fabrication and semiconductor device processing. The process comprises the steps of providing a single layer of either an amorphous silicon or hydrogenated amorphous silicon material. A pattern is recorded in a selected layer of amorphous silicon or hydrogenated amorphous silicon materials by preferentially implanting hydrogen ions therein so as to permit the selected layer to serve as a mask-resist wafer suitable for subsequent development and device fabrication. The layer is developed to provide a surface pattern therein adaptable for subsequent use in microelectronic fabrication and semiconductor device processing. 6 figs.

Boundary conditioning of capacitive MEMS devices through fabrication methods and operating environments

NASA Astrophysics Data System (ADS)

Muthukumaran, Packirisamy; Stiharu, Ion G.; Bhat, Rama B.

2003-10-01

This paper presents and applies the concept of micro-boundary conditioning to the design synthesis of microsystems in order to quantify the influence of inherent limitations of the fabrication process and the operating conditions on both static and dynamic behavior of microsystems. The predicted results on the static and dynamic behavior of a capacitive MEMS device, fabricated through MUMPs process, under the influence of the fabrication limitation and operating environment are presented along with the test results. The comparison between the predicted and experimental results shows a good agreement.

Fabrication of capsule assemblies, phase 3

NASA Technical Reports Server (NTRS)

Keeton, A. R.; Stemann, L. G.

1973-01-01

Thirteen capsule assemblies were fabricated for evaluation of fuel pin design concepts for a fast spectrum lithium cooled compact space power reactor. These instrumented assemblies were designed for real time test of prototype fuel pins. Uranium mononitride fuel pins were encased in AISI 304L stainless steel capsules. Fabrication procedures were fully qualified by process development and assembly qualification tests. Instrumentation reliability was achieved utilizing specially processed and closely controlled thermocouple hot zone fabrication and by thermal screening tests. Overall capsule reliability was achieved with an all electron beam welded assembly.

3D printing in X-ray and Gamma-Ray Imaging: A novel method for fabricating high-density imaging apertures☆

PubMed Central

Miller, Brian W.; Moore, Jared W.; Barrett, Harrison H.; Fryé, Teresa; Adler, Steven; Sery, Joe; Furenlid, Lars R.

2011-01-01

Advances in 3D rapid-prototyping printers, 3D modeling software, and casting techniques allow for cost-effective fabrication of custom components in gamma-ray and X-ray imaging systems. Applications extend to new fabrication methods for custom collimators, pinholes, calibration and resolution phantoms, mounting and shielding components, and imaging apertures. Details of the fabrication process for these components, specifically the 3D printing process, cold casting with a tungsten epoxy, and lost-wax casting in platinum are presented. PMID:22199414

Impact of process temperature on GaSb metal-oxide-semiconductor interface properties fabricated by ex-situ process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yokoyama, Masafumi, E-mail: yokoyama@mosfet.t.u-tokyo.ac.jp; Takenaka, Mitsuru; Takagi, Shinichi

We have studied the impact of process temperature on interface properties of GaSb metal-oxide-semiconductor (MOS) structures fabricated by an ex-situ atomic-layer-deposition (ALD) process. We have found that the ALD temperature strongly affects the Al{sub 2}O{sub 3}/GaSb MOS interface properties. The Al{sub 2}O{sub 3}/GaSb MOS interfaces fabricated at the low ALD temperature of 150 °C have the minimum interface-trap density (D{sub it}) of ∼4.5 × 10{sup 13 }cm{sup −2} eV{sup −1}. We have also found that the post-metalization annealing at temperature higher than 200 °C degrades the Al{sub 2}O{sub 3}/GaSb MOS interface properties. The low-temperature process is preferable in fabricating GaSb MOS interfaces in the ex-situmore » ALD process to avoid the high-temperature-induced degradations.« less

Experimental analysis for fabrication of high-aspect-ratio piezoelectric ceramic structure by micro-powder injection molding process

NASA Astrophysics Data System (ADS)

Han, Jun Sae; Gal, Chang Woo; Park, Jae Man; Kim, Jong Hyun; Park, Seong Jin

2018-04-01

Aspect ratio effects in the micro-powder injection molding process were experimentally analyzed for fabrication of high-aspect-ratio piezoelectric ceramic structure. The mechanisms of critical defects have been studied according to individual manufacturing steps. In the molding process, incomplete filling phenomenon determines the critical aspect ratios of a micro pattern. According to mold temperature, an incomplete filling phenomenon has been analyzed with respect to different pattern sizes and aspect ratio. In demolding and drying process, the capillary behavior of sacrificial polymeric mold insert determines the critical aspect ratio of a micro pattern. With respect to pattern dimensions, slumping behavior has been analyzed. Based on our current systems, micro PZT feature has stability when it has lower aspect ratio than 5. Under optimized processing conditions, 20 μm and 40 μm ceramic rod array feature which has 5 of aspect ratio were successfully fabricated by the developed process. Further modification points to fabricate the smaller and higher feature were specifically addressed.

Design for the automation of composite wind turbine blade manufacture

NASA Astrophysics Data System (ADS)

Polcari, M. J.; White, K. D.; Sherwood, J. A.

2016-10-01

The majority of large wind turbine blades are manufactured from textile-reinforced resin-infused composites using an open mold. The placement of the textile reinforcements in the mold is traditionally accomplished by a manual process where dozens of workers hand place each dry fabric in the mold. Depending on the level of skill and experience of each worker and the relative complexity of the mold geometry, local areas may exhibit out-of-plane wrinkling and in-plane waviness. Fabric imperfections such as these can adversely impact the strength and stiffness of the blade, thereby compromising its durability in service. In an effort to reduce the variabilities associated with a manual-labor process, an automated piecewise shifting method has been proposed for fabric placement. This automated layup method saves time on the preform process and reduces variability from blade to blade. In the current research the automated shifting layup method is investigated using a robust and easy-to-use finite element modelling approach. User-defined material models utilizing a mesoscopic unit-cell modeling approach are linked with Abaqus to capture the evolution of the fabric shear stiffness and changes in the fiber orientations during the fabric-placement process. The simulation approach is demonstrated for the geometry of the trailing edge of a typical wind turbine blade. The simulation considers the mechanical behavior of the fabric and reliably predicts fabric deformation and failure zones.

Development of Cotton Fabrics with Durable UV Protective and Self-cleaning Property by Deposition of Low TiO2 Levels through Sol-gel Process.

PubMed

Mishra, Anu; Butola, Bhupendra Singh

2018-01-19

In this article, the deposition of TiO 2 on cotton fabric using sol-gel technique has been described. Various process routes (pad-dry-cure, pad-dry-hydrothermal and pad-dry-solvothermal) were examined to impart a stable coating of TiO 2 on fabric. The role of precursor concentration, process temperature and time of treatment were studied to aim at a wash durable, UV protective and self-cleaning property in the treated fabric. EDX and ICP-MS techniques were used to examine the add-on percentage of TiO 2 on cotton fabrics treated via different routes. It has been found that the TiO 2 remains largely amorphous and nondurable if it is given a short thermal treatment. To convert the deposited TiO 2 to its anatase crystal form, a prolonged hydrothermal treatment for at least 3 h needs to be given. TiO 2 deposition levels of less than 0.1% were found to be effective in imparting reasonable degree of UV protection and self-cleaning property to the cotton fabric. The self-cleaning ability of the treated fabric against coffee stain was also studied and was found to be related to the process route and the deposition levels of TiO 2 . © 2018 The American Society of Photobiology.

Investigation of the influence of the proximity effect and randomness on a photolithographically fabricated photonic crystal nanobeam cavity

NASA Astrophysics Data System (ADS)

Tetsumoto, Tomohiro; Kumazaki, Hajime; Ishida, Rammaru; Tanabe, Takasumi

2018-01-01

Recent progress on the fabrication techniques used in silicon photonics foundries has enabled us to fabricate photonic crystal (PhC) nanocavities using a complementary metal-oxide-semiconductor (CMOS) compatible process. A high Q two-dimensional PhC nanocavity and a one-dimensional nanobeam PhC cavity with a Q exceeding 100 thousand have been fabricated using ArF excimer laser immersion lithography. These are important steps toward the fusion of silicon photonics devices and PhC devices. Although the fabrication must be reproducible for industrial applications, the properties of PhC nanocavities are sensitively affected by the proximity effect and randomness. In this study, we quantitatively investigated the influence of the proximity effect and randomness on a silicon nanobeam PhC cavity. First, we discussed the optical properties of cavities defined with one- and two-step exposure methods, which revealed the necessity of a multi-stage exposure process for our structure. Then, we investigated the impact of block structures placed next to the cavities. The presence of the blocks modified the resonant wavelength of the cavities by about 10 nm. The highest Q we obtained was over 100 thousand. We also discussed the influence of photomask misalignment, which is also a possible cause of disorders in the photolithographic fabrication process. This study will provide useful information for fabricating integrated photonic circuits with PhC nanocavities using a photolithographic process.

A sacrificial process for fabrication of biodegradable polymer membranes with submicron thickness.

PubMed

Beardslee, Luke A; Stolwijk, Judith; Khaladj, Dimitrius A; Trebak, Mohamed; Halman, Justin; Torrejon, Karen Y; Niamsiri, Nuttawee; Bergkvist, Magnus

2016-08-01

A new sacrificial molding process using a single mask has been developed to fabricate ultrathin 2-dimensional membranes from several biocompatible polymeric materials. The fabrication process is similar to a sacrificial microelectromechanical systems (MEMS) process flow, where a mold is created from a material that can be coated with a biodegradable polymer and subsequently etched away, leaving behind a very thin polymer membrane. In this work, two different sacrificial mold materials, silicon dioxide (SiO2 ) and Liftoff Resist (LOR) were used. Three different biodegradable materials; polycaprolactone (PCL), poly(lactic-co-glycolic acid) (PLGA), and polyglycidyl methacrylate (PGMA), were chosen as model polymers. We demonstrate that this process is capable of fabricating 200-500 nm thin, through-hole polymer membranes with various geometries, pore-sizes and spatial features approaching 2.5 µm using a mold fabricated via a single contact photolithography exposure. In addition, the membranes can be mounted to support rings made from either SU8 or PCL for easy handling after release. Cell culture compatibility of the fabricated membranes was evaluated with human dermal microvascular endothelial cells (HDMECs) seeded onto the ultrathin porous membranes, where the cells grew and formed confluent layers with well-established cell-cell contacts. Furthermore, human trabecular meshwork cells (HTMCs) cultured on these scaffolds showed similar proliferation as on flat PCL substrates, further validating its compatibility. All together, these results demonstrated the feasibility of our sacrificial fabrication process to produce biocompatible, ultra-thin membranes with defined microstructures (i.e., pores) with the potential to be used as substrates for tissue engineering applications. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1192-1201, 2016. © 2015 Wiley Periodicals, Inc.

Toward large-area roll-to-roll printed nanophotonic sensors

NASA Astrophysics Data System (ADS)

Karioja, Pentti; Hiltunen, Jussi; Aikio, Sanna M.; Alajoki, Teemu; Tuominen, Jarkko; Hiltunen, Marianne; Siitonen, Samuli; Kontturi, Ville; Böhlen, Karl; Hauser, Rene; Charlton, Martin; Boersma, Arjen; Lieberzeit, Peter; Felder, Thorsten; Eustace, David; Haskal, Eliav

2014-05-01

Polymers have become an important material group in fabricating discrete photonic components and integrated optical devices. This is due to their good properties: high optical transmittance, versatile processability at relative low temperatures and potential for low-cost production. Recently, nanoimprinting or nanoimprint lithography (NIL) has obtained a plenty of research interest. In NIL, a mould is pressed against a substrate coated with a moldable material. After deformation of the material, the mold is separated and a replica of the mold is formed. Compared with conventional lithographic methods, imprinting is simple to carry out, requires less-complicated equipment and can provide high-resolution with high throughput. Nanoimprint lithography has shown potential to become a method for low-cost and high-throughput fabrication of nanostructures. We show the development process of nano-structured, large-area multi-parameter sensors using Photonic Crystal (PC) and Surface Enhanced Raman Scattering (SERS) methodologies for environmental and pharmaceutical applications. We address these challenges by developing roll-to-roll (R2R) UV-nanoimprint fabrication methods. Our development steps are the following: Firstly, the proof of concept structures are fabricated by the use of wafer-level processes in Si-based materials. Secondly, the master molds of successful designs are fabricated, and they are used to transfer the nanophotonic structures into polymer materials using sheet-level UV-nanoimprinting. Thirdly, the sheet-level nanoimprinting processes are transferred to roll-to-roll fabrication. In order to enhance roll-to-roll manufacturing capabilities, silicone-based polymer material development was carried out. In the different development phases, Photonic Crystal and SERS sensor structures with increasing complexities were fabricated using polymer materials in order to enhance sheet-level and roll-to-roll manufacturing processes. In addition, chemical and molecular imprint (MIP) functionalization methods were applied in the sensor demonstrators. In this paper, the process flow in fabricating large-area nanophotonic structures by the use of sheet-level and roll-to-roll UV- nanoimprinting is reported.

Electromagnetic microforging apparatus for low-cost fabrication of molds for microlens arrays

NASA Astrophysics Data System (ADS)

Pribošek, Jaka; Diaci, Janez

2015-06-01

This study addresses the problem of low-cost microlens fabrication and outlines the development of a novel microforging apparatus for microlens mold fabrication. The apparatus consists of an electromagnetic impact tool which strikes a piston with a hardened steel ball into a workpiece. The impact creates a spherical indentation which serves as a lens cavity. The microforging apparatus is controlled by a microprocessor control unit communicating with a personal computer and enables on-the-fly variation of electromagnetic excitation to control the microforging process. We studied the effects of process parameters on the diameter of the fabricated lens cavities inspected by a custom automatic image processing algorithm. Different microforging regimes are analyzed and discussed. The surface quality of fabricated cavities has been inspected by confocal microscopy and the influence of fill factor on sphericity error has been studied. The proposed microforging method enables the fabrication of molds with 100% fill factor, surface roughness as low as Ra 0.15 µm and sphericity error lower than 0.5 µm. The fabricated microlens arrays exhibit nearly diffraction-limited performance, offering a wide range of possible applications. We believe this study provides access to microoptical technology for smaller optical and computer vision laboratories.

Using rapid infrared forming to control interfaces in titanium-matrix composites

NASA Technical Reports Server (NTRS)

Warrier, Sunil G.; Lin, Ray Y.

1993-01-01

Control of the fiber-matrix reaction during composite fabrication is commonly achieved by shortening the processing time, coating the reinforcement with relatively inert materials, or adding alloying elements to retard the reaction. To minimize the processing time, a rapid IR forming (RIF) technique for metal-matrix composite fabrication has been developed. Experiments have shown that the RIF technique is a quick, simple, and low-cost process to fabricate titanium-alloy matrix composites reinforced with either silicon carbide or carbon fibers. Due to short processing times (typically on the order of 1-2 minutes in an inert atmosphere for composites with up to eight-ply reinforcements), the interfacial reaction is limited and well controlled. Composites fabricated by this technique have mechanical properties that are comparable to (in several cases, superior to) those made with conventional diffusion-bonding techniques.

Fabrication of three-dimensional collagen scaffold using an inverse mould-leaching process.

PubMed

Ahn, SeungHyun; Lee, SuYeon; Cho, Youngseok; Chun, Wook; Kim, GeunHyung

2011-09-01

Natural biopolymers, such as collagen or chitosan, are considered ideal for biomedical scaffolds. However, low processability of the materials has hindered the fabrication of designed pore structures controlled by various solid freeform-fabrication methods. A new technique to fabricate a biomedical three-dimensional collagen scaffold, supplemented with a sacrificial poly(ethylene oxide) mould is proposed. The fabricated collagen scaffold shows a highly porous surface and a three-dimensional structure with high porosity as well as mechanically stable structure. To show its feasibility for biomedical applications, fibroblasts/keratinocytes were co-cultured on the scaffold, and the cell proliferation and cell migration of the scaffold was more favorable than that obtained with a spongy-type collagen scaffold.

Modified rod-in-tube for high-NA tellurite glass fiber fabrication: materials and technologies.

PubMed

Chen, Qiuling; Wang, Hui; Wang, Qingwei; Chen, Qiuping; Hao, Yinlei

2015-02-01

In this paper, we report the whole fabrication process for high-numerical aperture (NA) tellurite glass fibers from material preparation to preform fabrication, and eventually, fiber drawing. A tellurite-based high-NA (0.9) magneto-optical glass fiber was drawn successfully and characterized. First, matchable core and cladding glasses were fabricated and matched in terms of physical properties. Second, a uniform bubble-free preform was fabricated by means of a modified rod-in-tube technique. Finally, the fiber drawing process was studied and optimized. The high-NA fibers (∅(core), 40-50 μm and ∅(cladding), 120-130 μm) so obtained were characterized for their geometrical and optical properties.

In-process fault detection for textile fabric production: onloom imaging

NASA Astrophysics Data System (ADS)

Neumann, Florian; Holtermann, Timm; Schneider, Dorian; Kulczycki, Ashley; Gries, Thomas; Aach, Til

2011-05-01

Constant and traceable high fabric quality is of high importance both for technical and for high-quality conventional fabrics. Usually, quality inspection is carried out by trained personal, whose detection rate and maximum period of concentration are limited. Low resolution automated fabric inspection machines using texture analysis were developed. Since 2003, systems for the in-process inspection on weaving machines ("onloom") are commercially available. With these defects can be detected, but not measured quantitative precisely. Most systems are also prone to inevitable machine vibrations. Feedback loops for fault prevention are not established. Technology has evolved since 2003: Camera and computer prices dropped, resolutions were enhanced, recording speeds increased. These are the preconditions for real-time processing of high-resolution images. So far, these new technological achievements are not used in textile fabric production. For efficient use, a measurement system must be integrated into the weaving process; new algorithms for defect detection and measurement must be developed. The goal of the joint project is the development of a modern machine vision system for nondestructive onloom fabric inspection. The system consists of a vibration-resistant machine integration, a high-resolution machine vision system, and new, reliable, and robust algorithms with quality database for defect documentation. The system is meant to detect, measure, and classify at least 80 % of economically relevant defects. Concepts for feedback loops into the weaving process will be pointed out.

A strategy for design and fabrication of low cost microchannel for future reproductivity of bio/chemical lab-on-chip application

NASA Astrophysics Data System (ADS)

Humayun, Q.; Hashim, U.; Ruzaidi, C. M.; Noriman, N. Z.

2017-03-01

The fabrication and characterization of sensitive and selective fluids delivery system for the application of nano laboratory on a single chip is a challenging task till to date. This paper is one of the initial attempt to resolve this challenging task by using a simple, cost effective and reproductive technique for pattering a microchannel structures on SU-8 resist. The objective of the research is to design, fabricate and characterize polydimethylsiloxane (PDMS) microchannel. The proposed device mask was designed initially by using AutoCAD software and then the designed was transferred to transparency sheet and to commercial chrome mask for better photo masking process. The standard photolithography process coupled with wet chemical etching process was used for the fabrication of proposed microchannel. This is a low cost fabrication technique for the formation of microchannel structure at resist. The fabrication process start from microchannel formation and then the structure was transformed to PDMS substrate, the microchannel structure was cured from mold and then the cured mold was bonded with the glass substrate by plasma oxidation bonding process. The surface morphology was characterized by high power microscope (HPM) and the structure was characterized by Hawk 3 D surface nanoprofiler. The next part of the research will be focus onto device testing and validation by using real biological samples by the implementation of a simple manual injection technique.

Stereolithographic processing of ceramics: Photon diffusion in colloidal dispersion

NASA Astrophysics Data System (ADS)

Garg, Rajeev

The technique of ceramic stereolithography (CSL) has been developed for fabricating near net shape ceramic objects. In stereolithography, the three-dimensional computer design file of the object is sliced into thin layers. Each layer is physically fabricated by photocuring the surface of a liquid photo-polymerizable resin bath by raster scanning an ultra-violet laser across the surface of the resin. In CSL, the liquid resin is a high concentration colloidal dispersion in a solution of ultraviolet curable polymers. The ceramic green body fabricated by ceramic stereolithography technique is subjected to the post processing steps of drying, binder burnout and sintering to form a dense ceramic object. An aqueous alumina dispersion in photocuring polymers with particle volume fraction greater than 0.5 was formulated for CSL process. Low molecular weight solution polymers were found to be best suited for formulating ceramic resins due to their inherently low viscosity and favorable interactions with the ceramic dispersant. A hydroxyapatite ceramic resin was also developed for the use in the CSL technique. A model is developed to describe the photocuring process in concentrated ceramic dispersion. The curing profile in ceramic dispersion is governed by multiple scattering from the ceramic particles and absorption by the photocuring polymers. Diffusion theory of light transport is used to model the multiple scattering and absorption phenomena. It is found that diffusive transport adequately describes the phenomena of laser pulse propagation in highly concentrated colloidal dispersions. A model was developed to describe the absorption in highly concentrated ceramic dispersion. Various complex-shaped monolithic alumina and hydroxyapatite objects were fabricated by CSL and shown to possess uniform microstructure. The mechanical properties and sintering behavior of the parts fabricated by CSL are shown to be comparable to those fabricated by other ceramic processing technique. An application of CSL has been established for fabricating orthopedic implants. Orthopedic implants and biomedical devices of defined micro and macro architecture with controlled pore sizes and porosity were fabricated by CSL. The bone implants were also fabricated form in vivo scan of the bone. The structures were implanted in rats to understand the biocompatibility of CSL fabricated parts.

Finite Element Simulation of Compression Molding of Woven Fabric Carbon Fiber/Epoxy Composites: Part I Material Model Development

DOE PAGES

Li, Yang; Zhao, Qiangsheng; Mirdamadi, Mansour; ...

2016-01-06

Woven fabric carbon fiber/epoxy composites made through compression molding are one of the promising choices of material for the vehicle light-weighting strategy. Previous studies have shown that the processing conditions can have substantial influence on the performance of this type of the material. Therefore the optimization of the compression molding process is of great importance to the manufacturing practice. An efficient way to achieve the optimized design of this process would be through conducting finite element (FE) simulations of compression molding for woven fabric carbon fiber/epoxy composites. However, performing such simulation remains a challenging task for FE as multiple typesmore » of physics are involved during the compression molding process, including the epoxy resin curing and the complex mechanical behavior of woven fabric structure. In the present study, the FE simulation of the compression molding process of resin based woven fabric composites at continuum level is conducted, which is enabled by the implementation of an integrated material modeling methodology in LS-Dyna. Specifically, the chemo-thermo-mechanical problem of compression molding is solved through the coupling of three material models, i.e., one thermal model for temperature history in the resin, one mechanical model to update the curing-dependent properties of the resin and another mechanical model to simulate the behavior of the woven fabric composites. Preliminary simulations of the carbon fiber/epoxy woven fabric composites in LS-Dyna are presented as a demonstration, while validations and models with real part geometry are planned in the future work.« less

Innovative layer-by-layer processing for flame retardant behavior of cotton fabric

USDA-ARS?s Scientific Manuscript database

Flame retardant behavior has been prepared by the layer-by layer assemblies of kaolin/casein with inorganic chemicals on cotton fabrics. Three different kinds of cotton fabrics (print cloth, mercerized print cloth, and mercerized twill fabric) were prepared with solutions of mixture of BPEI, urea, ...

Al transmon qubits on silicon-on-insulator for quantum device integration

NASA Astrophysics Data System (ADS)

Keller, Andrew J.; Dieterle, Paul B.; Fang, Michael; Berger, Brett; Fink, Johannes M.; Painter, Oskar

2017-07-01

We present the fabrication and characterization of an aluminum transmon qubit on a silicon-on-insulator substrate. Key to the qubit fabrication is the use of an anhydrous hydrofluoric vapor process which selectively removes the lossy silicon oxide buried underneath the silicon device layer. For a 5.6 GHz qubit measured dispersively by a 7.1 GHz resonator, we find T1 = 3.5 μs and T2* = 2.2 μs. This process in principle permits the co-fabrication of silicon photonic and mechanical elements, providing a route towards chip-scale integration of electro-opto-mechanical transducers for quantum networking of superconducting microwave quantum circuits. The additional processing steps are compatible with established fabrication techniques for aluminum transmon qubits on silicon.

High Resolution Fabrication of Interconnection Lines Using Picosecond Laser and Controlled Deposition of Gold Nanoparticles

NASA Astrophysics Data System (ADS)

Shahmoon, Asaf; Strauß, Johnnes; Zafri, Hadar; Schmidt, Michael; Zalevsky, Zeev

In this paper we present the fabrication procedure as well as the preliminary experimental results of a novel method for construction of high resolution nanometric interconnection lines. The fabrication procedure relies on a self-assembly process of gold nanoparticles at specific predetermined nanostructures. The nanostructures for the self-assembly process are based on the focused ion beam (FIB) or scanning electron beam (SEM) technology. The assembled nanoparticles are being illuminated using a picosecond laser with a wavelength of 532 nm. Different pulse energies have been investigated. The paper aimed at developing a novel and reliable process for fabrication of interconnection lines encompass three different disciplines, self-assembly of nanometric particles, optics and microelectronic.

Method for double-sided processing of thin film transistors

DOEpatents

Yuan, Hao-Chih; Wang, Guogong; Eriksson, Mark A.; Evans, Paul G.; Lagally, Max G.; Ma, Zhenqiang

2008-04-08

This invention provides methods for fabricating thin film electronic devices with both front- and backside processing capabilities. Using these methods, high temperature processing steps may be carried out during both frontside and backside processing. The methods are well-suited for fabricating back-gate and double-gate field effect transistors, double-sided bipolar transistors and 3D integrated circuits.

Front and backside processed thin film electronic devices

DOEpatents

Yuan, Hao-Chih; Wang, Guogong; Eriksson, Mark A.; Evans, Paul G.; Lagally, Max G.; Ma, Zhenqiang

2010-10-12

This invention provides methods for fabricating thin film electronic devices with both front- and backside processing capabilities. Using these methods, high temperature processing steps may be carried out during both frontside and backside processing. The methods are well-suited for fabricating back-gate and double-gate field effect transistors, double-sided bipolar transistors and 3D integrated circuits.

A novel, two-step top seeded infiltration and growth process for the fabrication of single grain, bulk (RE)BCO superconductors

NASA Astrophysics Data System (ADS)

Namburi, Devendra K.; Shi, Yunhua; Palmer, Kysen G.; Dennis, Anthony R.; Durrell, John H.; Cardwell, David A.

2016-09-01

A fundamental requirement of the fabrication of high performing, (RE)-Ba-Cu-O bulk superconductors is achieving a single grain microstructure that exhibits good flux pinning properties. The top seeded melt growth (TSMG) process is a well-established technique for the fabrication of single grain (RE)BCO bulk samples and is now applied routinely by a number of research groups around the world. The introduction of a buffer layer to the TSMG process has been demonstrated recently to improve significantly the general reliability of the process. However, a number of growth-related defects, such as porosity and the formation of micro-cracks, remain inherent to the TSMG process, and are proving difficult to eliminate by varying the melt process parameters. The seeded infiltration and growth (SIG) process has been shown to yield single grain samples that exhibit significantly improved microstructures compared to the TSMG technique. Unfortunately, however, SIG leads to other processing challenges, such as the reliability of fabrication, optimisation of RE2BaCuO5 (RE-211) inclusions (size and content) in the sample microstructure, practical oxygenation of as processed samples and, hence, optimisation of the superconducting properties of the bulk single grain. In the present paper, we report the development of a near-net shaping technique based on a novel two-step, buffer-aided top seeded infiltration and growth (BA-TSIG) process, which has been demonstrated to improve greatly the reliability of the single grain growth process and has been used to fabricate successfully bulk, single grain (RE)BCO superconductors with improved microstructures and superconducting properties. A trapped field of ˜0.84 T and a zero field current density of 60 kA cm-2 have been measured at 77 K in a bulk, YBCO single grain sample of diameter 25 mm processed by this two-step BA-TSIG technique. To the best of our knowledge, this value of trapped field is the highest value ever reported for a sample fabricated by an infiltration and growth process. In this study we report the successful fabrication of 14 YBCO samples, with diameters of up to 32 mm, by this novel technique with a success rate of greater than 92%.

Integrated 3D printing and corona poling process of PVDF piezoelectric films for pressure sensor application

NASA Astrophysics Data System (ADS)

Kim, Hoejin; Torres, Fernando; Wu, Yanyu; Villagran, Dino; Lin, Yirong; Tseng, Tzu-Liang(Bill

2017-08-01

This paper presents a novel process to fabricate piezoelectric films from polyvinylidene fluoride (PVDF) polymer using integrated fused deposition modeling (FDM) 3D printing and corona poling technique. Corona poling is one of many effective poling processes that has received attention to activate PVDF as a piezoelectric responsive material. The corona poling process occurs when a PVDF polymer is exposed to a high electric field created and controlled through an electrically charged needle and a grid electrode under heating environment. FDM 3D printing has seen extensive progress in fabricating thermoplastic materials and structures, including PVDF. However, post processing techniques such as poling is needed to align the dipoles in order to gain piezoelectric properties. To further simplify the piezoelectric sensors and structures fabrication process, this paper proposes an integrated 3D printing process with corona poling to fabricate piezoelectric PVDF sensors without post poling process. This proposed process, named ‘Integrated 3D Printing and Corona poling process’ (IPC), uses the 3D printer’s nozzle and heating bed as anode and cathode, respectively, to create poling electric fields in a controlled heating environment. The nozzle travels along the programmed path with fixed distance between nozzle tip and sample’s top surface. Simultaneously, the electric field between the nozzle and bottom heating pad promotes the alignment of dipole moment of PVDF molecular chains. The crystalline phase transformation and output current generated by printed samples under different electric fields in this process were characterized by a Fourier transform infrared spectroscopy and through fatigue load frame. It is demonstrated that piezoelectric PVDF films with enhanced β-phase percentage can be fabricated using the IPC process. In addition, mechanical properties of printed PVDF was investigated by tensile testing. It is expected to expand the use of additive manufacturing to fabricate piezoelectric PVDF-based devices for applications such as sensing and energy harvesting.

Robust and durable superhydrophobic fabrics fabricated via simple Cu nanoparticles deposition route and its application in oil/water separation.

PubMed

Wang, Jintao; Wang, Hongfei

2017-06-15

The exploitation of separation materials with high selectivity for oil pollutants is of great importance due to severe environmental damage from oil spillages and industrial discharge of oils. A facile in situ growth process for creating superhydrophobic-superoleophilic fabrics for oil-water separation is developed. This proposed method is based mainly on the deposition Cu nanoparticles and subsequent hydrophobic modification. Compared with the hydrophilicity of original fabric, the water contact angle of the modified fabric rises to 154.5°, suggesting its superhydrophobicity. The as-prepared fabrics also exhibit wonderful oil-water selectivity, excellent recyclability, and high separation efficiency (>94.5%). Especially, via pumping the fabric rolled into a multilayered tube, various types of oils on water surface can be continuously separated in situ without any water uptake. Furthermore, the superhydrophobic fabrics show excellent superhydrophobic stability, and can resist different chemicals, such as salty, acidic, and alkaline solutions, oils, and hot water. After the abrasion of 400cycles, the broken fabric still possesses highly hydrophobicity with water contact angle of 145°. Therefore, due to simple fabrication steps, low cost, and scalable process, the as-prepared fabrics can be applied in the separation of oils and other organic solvents from water. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nanoparticle Selective Laser Processing for a Flexible Display Fabrication

NASA Astrophysics Data System (ADS)

Seung Hwan Ko,; Heng Pan,; Daeho Lee,; Costas P. Grigoropoulos,; Hee K. Park,

2010-05-01

To demonstrate a first step for a novel fabrication method of a flexible display, nanomaterial based laser processing schemes to demonstrate organic light emitting diode (OLED) pixel transfer and organic field effect transistor (OFET) fabrication on a polymer substrate without using any conventional vacuum or photolithography processes were developed. The unique properties of nanomaterials allow laser induced forward transfer of organic light emitting material at low laser energy while maintaining good fluorescence and also allow high resolution transistor electrode patterning at plastic compatible low temperature. These novel processes enable an environmentally friendly and cost effective process as well as a low temperature manufacturing sequence to realize inexpensive, large area, flexible electronics on polymer substrates.

Using Micro-Molding and Stamping to Fabricate Conductive Polydimethylsiloxane-Based Flexible High-Sensitivity Strain Gauges.

PubMed

Han, Chi-Jui; Chiang, Hsuan-Ping; Cheng, Yun-Chien

2018-02-18

In this study, polydimethylsiloxane (PDMS) and conductive carbon nanoparticles were combined to fabricate a conductive elastomer PDMS (CPDMS). A high sensitive and flexible CPDMS strain sensor is fabricated by using stamping-process based micro patterning. Compared with conventional sensors, flexible strain sensors are more suitable for medical applications but are usually fabricated by photolithography, which suffers from a large number of steps and difficult mass production. Hence, we fabricated flexible strain sensors using a stamping-process with fewer processes than photolithography. The piezoresistive coefficient and sensitivity of the flexible strain sensor were improved by sensor pattern design and thickness change. Micro-patterning is used to fabricate various CPDMS microstructure patterns. The effect of gauge pattern was evaluated with ANSYS simulations. The piezoresistance of the strain gauges was measured and the gauge factor determined. Experimental results show that the piezoresistive coefficient of CPDMS is approximately linear. Gauge factor measurement results show that the gauge factor of a 140.0 μm thick strain gauge with five grids is the highest.

A programmable nanoreplica molding for the fabrication of nanophotonic devices.

PubMed

Liu, Longju; Zhang, Jingxiang; Badshah, Mohsin Ali; Dong, Liang; Li, Jingjing; Kim, Seok-min; Lu, Meng

2016-03-01

The ability to fabricate periodic structures with sub-wavelength features has a great potential for impact on integrated optics, optical sensors, and photovoltaic devices. Here, we report a programmable nanoreplica molding process to fabricate a variety of sub-micrometer periodic patterns using a single mold. The process utilizes a stretchable mold to produce the desired periodic structure in a photopolymer on glass or plastic substrates. During the replica molding process, a uniaxial force is applied to the mold and results in changes of the periodic structure, which resides on the surface of the mold. Direction and magnitude of the force determine the array geometry, including the lattice constant and arrangement. By stretching the mold, 2D arrays with square, rectangular, and triangular lattice structures can be fabricated. As one example, we present a plasmonic crystal device with surface plasmon resonances determined by the force applied during molding. In addition, photonic crystal slabs with different array patterns are fabricated and characterized. This unique process offers the capability of generating various periodic nanostructures rapidly and inexpensively.

Fabrication of Well-Ordered, Anodic Aluminum Oxide Membrane Using Hybrid Anodization.

PubMed

Kim, Jungyoon; Ganorkar, Shraddha; Choi, Jinnil; Kim, Young-Hwan; Kim, Seong-II

2017-01-01

Anodic Aluminum Oxide (AAO) is one of the most favorable candidates for fabrication of nano-meshed membrane for various applications due to its controllable pore size and self-ordered structure. The mechanism of AAO membrane is a simple and has been studied by many research groups, however the actual fabrication of membrane has several difficulties owing to its sensitivity of ordering, long anodizing time and unclearness of the pore. In this work, we have demonstrated enhanced process of fabrication symmetric AAO membrane by using “hybrid anodizing” (Hyb-A) method which include mild anodization (MA) followed by hard anodization (HA). This Hyb-A process can give highly ordered membrane with more vivid pore than two-step anodizing process. HA was implemented on the Al plate which has been already textured by MA for more ordered structure and HA plays a key role for formation of more obvious pore in Hyb-A. Our experimental results indicate that Hyb-A with proper process sequence would be one of the fast and useful fabrication methods for the AAO membrane.

A programmable nanoreplica molding for the fabrication of nanophotonic devices

PubMed Central

Liu, Longju; Zhang, Jingxiang; Badshah, Mohsin Ali; Dong, Liang; Li, Jingjing; Kim, Seok-min; Lu, Meng

2016-01-01

The ability to fabricate periodic structures with sub-wavelength features has a great potential for impact on integrated optics, optical sensors, and photovoltaic devices. Here, we report a programmable nanoreplica molding process to fabricate a variety of sub-micrometer periodic patterns using a single mold. The process utilizes a stretchable mold to produce the desired periodic structure in a photopolymer on glass or plastic substrates. During the replica molding process, a uniaxial force is applied to the mold and results in changes of the periodic structure, which resides on the surface of the mold. Direction and magnitude of the force determine the array geometry, including the lattice constant and arrangement. By stretching the mold, 2D arrays with square, rectangular, and triangular lattice structures can be fabricated. As one example, we present a plasmonic crystal device with surface plasmon resonances determined by the force applied during molding. In addition, photonic crystal slabs with different array patterns are fabricated and characterized. This unique process offers the capability of generating various periodic nanostructures rapidly and inexpensively. PMID:26925828

Next Generation Non-Vacuum, Maskless, Low Temperature Nanoparticle Ink Laser Digital Direct Metal Patterning for a Large Area Flexible Electronics

PubMed Central

Yeo, Junyeob; Hong, Sukjoon; Lee, Daehoo; Hotz, Nico; Lee, Ming-Tsang; Grigoropoulos, Costas P.; Ko, Seung Hwan

2012-01-01

Flexible electronics opened a new class of future electronics. The foldable, light and durable nature of flexible electronics allows vast flexibility in applications such as display, energy devices and mobile electronics. Even though conventional electronics fabrication methods are well developed for rigid substrates, direct application or slight modification of conventional processes for flexible electronics fabrication cannot work. The future flexible electronics fabrication requires totally new low-temperature process development optimized for flexible substrate and it should be based on new material too. Here we present a simple approach to developing a flexible electronics fabrication without using conventional vacuum deposition and photolithography. We found that direct metal patterning based on laser-induced local melting of metal nanoparticle ink is a promising low-temperature alternative to vacuum deposition– and photolithography-based conventional metal patterning processes. The “digital” nature of the proposed direct metal patterning process removes the need for expensive photomask and allows easy design modification and short turnaround time. This new process can be extremely useful for current small-volume, large-variety manufacturing paradigms. Besides, simple, scalable, fast and low-temperature processes can lead to cost-effective fabrication methods on a large-area polymer substrate. The developed process was successfully applied to demonstrate high-quality Ag patterning (2.1 µΩ·cm) and high-performance flexible organic field effect transistor arrays. PMID:22900011

Next generation non-vacuum, maskless, low temperature nanoparticle ink laser digital direct metal patterning for a large area flexible electronics.

PubMed

Yeo, Junyeob; Hong, Sukjoon; Lee, Daehoo; Hotz, Nico; Lee, Ming-Tsang; Grigoropoulos, Costas P; Ko, Seung Hwan

2012-01-01

Flexible electronics opened a new class of future electronics. The foldable, light and durable nature of flexible electronics allows vast flexibility in applications such as display, energy devices and mobile electronics. Even though conventional electronics fabrication methods are well developed for rigid substrates, direct application or slight modification of conventional processes for flexible electronics fabrication cannot work. The future flexible electronics fabrication requires totally new low-temperature process development optimized for flexible substrate and it should be based on new material too. Here we present a simple approach to developing a flexible electronics fabrication without using conventional vacuum deposition and photolithography. We found that direct metal patterning based on laser-induced local melting of metal nanoparticle ink is a promising low-temperature alternative to vacuum deposition- and photolithography-based conventional metal patterning processes. The "digital" nature of the proposed direct metal patterning process removes the need for expensive photomask and allows easy design modification and short turnaround time. This new process can be extremely useful for current small-volume, large-variety manufacturing paradigms. Besides, simple, scalable, fast and low-temperature processes can lead to cost-effective fabrication methods on a large-area polymer substrate. The developed process was successfully applied to demonstrate high-quality Ag patterning (2.1 µΩ·cm) and high-performance flexible organic field effect transistor arrays.

The effects of processing techniques on magnesium-based composite

NASA Astrophysics Data System (ADS)

Rodzi, Siti Nur Hazwani Mohamad; Zuhailawati, Hussain

2016-12-01

The aim of this study is to investigate the effect of processing techniques on the densification, hardness and compressive strength of Mg alloy and Mg-based composite for biomaterial application. The control sample (pure Mg) and Mg-based composite (Mg-Zn/HAp) were fabricated through mechanical alloying process using high energy planetary mill, whilst another Mg-Zn/HAp composite was fabricated through double step processing (the matrix Mg-Zn alloy was fabricated by planetary mill, subsequently HAp was dispersed by roll mill). As-milled powder was then consolidated by cold press into 10 mm diameter pellet under 400 MPa compaction pressure before being sintered at 300 °C for 1 hour under the flow of argon. The densification of the sintered pellets were then determined by Archimedes principle. Mechanical properties of the sintered pellets were characterized by microhardness and compression test. The results show that the density of the pellets was significantly increased by addition of HAp, but the most optimum density was observed when the sample was fabricated through double step processing (1.8046 g/cm3). Slight increment in hardness and ultimate compressive strength were observed for Mg-Zn/HAp composite that was fabricated through double step processing (58.09 HV, 132.19 MPa), as compared to Mg-Zn/HAp produced through single step processing (47.18 HV, 122.49 MPa).

Improved Method of Manufacturing SiC Devices

NASA Technical Reports Server (NTRS)

Okojie, Robert S.

2005-01-01

The phrase, "common-layered architecture for semiconductor silicon carbide" ("CLASSiC") denotes a method of batch fabrication of microelectromechanical and semiconductor devices from bulk silicon carbide. CLASSiC is the latest in a series of related methods developed in recent years in continuing efforts to standardize SiC-fabrication processes. CLASSiC encompasses both institutional and technological innovations that can be exploited separately or in combination to make the manufacture of SiC devices more economical. Examples of such devices are piezoresistive pressure sensors, strain gauges, vibration sensors, and turbulence-intensity sensors for use in harsh environments (e.g., high-temperature, high-pressure, corrosive atmospheres). The institutional innovation is to manufacture devices for different customers (individuals, companies, and/or other entities) simultaneously in the same batch. This innovation is based on utilization of the capability for fabrication, on the same substrate, of multiple SiC devices having different functionalities (see figure). Multiple customers can purchase shares of the area on the same substrate, each customer s share being apportioned according to the customer s production-volume requirement. This makes it possible for multiple customers to share costs in a common foundry, so that the capital equipment cost per customer in the inherently low-volume SiC-product market can be reduced significantly. One of the technological innovations is a five-mask process that is based on an established set of process design rules. The rules provide for standardization of the fabrication process, yet are flexible enough to enable multiple customers to lay out masks for their portions of the SiC substrate to provide for simultaneous batch fabrication of their various devices. In a related prior method, denoted multi-user fabrication in silicon carbide (MUSiC), the fabrication process is based largely on surface micromachining of poly SiC. However, in MUSiC one cannot exploit the superior sensing, thermomechanical, and electrical properties of single-crystal 6H-SiC or 4H-SiC. As a complement to MUSiC, the CLASSiC five-mask process can be utilized to fabricate multiple devices in bulk single-crystal SiC of any polytype. The five-mask process makes fabrication less complex because it eliminates the need for large-area deposition and removal of sacrificial material. Other innovations in CLASSiC pertain to selective etching of indium tin oxide and aluminum in connection with multilayer metallization. One major characteristic of bulk micromachined microelectromechanical devices is the presence of three-dimensional (3D) structures. Any 3D recesses that already exist at a given step in a fabrication process usually make it difficult to apply a planar coat of photoresist for metallization and other subsequent process steps. To overcome this difficulty, the CLASSiC process includes a reversal of part of the conventional flow: Metallization is performed before the recesses are etched.

A low-cost, high-yield fabrication method for producing optimized biomimetic dry adhesives

NASA Astrophysics Data System (ADS)

Sameoto, D.; Menon, C.

2009-11-01

We present a low-cost, large-scale method of fabricating biomimetic dry adhesives. This process is useful because it uses all photosensitive polymers with minimum fabrication costs or complexity to produce molds for silicone-based dry adhesives. A thick-film lift-off process is used to define molds using AZ 9260 photoresist, with a slow acting, deep UV sensitive material, PMGI, used as both an adhesion promoter for the AZ 9260 photoresist and as an undercutting material to produce mushroom-shaped fibers. The benefits to this process are ease of fabrication, wide range of potential layer thicknesses, no special surface treatment requirements to demold silicone adhesives and easy stripping of the full mold if process failure does occur. Sylgard® 184 silicone is used to cast full sheets of biomimetic dry adhesives off 4" diameter wafers, and different fiber geometries are tested for normal adhesion properties. Additionally, failure modes of the adhesive during fabrication are noted and strategies for avoiding these failures are discussed. We use this fabrication method to produce different fiber geometries with varying cap diameters and test them for normal adhesion strengths. The results indicate that the cap diameters relative to post diameters for mushroom-shaped fibers dominate the adhesion properties.

Automatic measurement for dimensional changes of woven fabrics based on texture

NASA Astrophysics Data System (ADS)

Liu, Jihong; Jiang, Hongxia; Liu, X.; Chai, Zhilei

2014-01-01

Dimensional change or shrinkage is an important functional attribute of woven fabrics that affects their basic function and price in the market. This paper presents a machine vision system that evaluates the shrinkage of woven fabrics by analyzing the change of fabric construction. The proposed measurement method has three features. (i) There will be no stain of shrinkage markers on the fabric specimen compared to the existing measurement method. (ii) The system can be used on fabric with reduced area. (iii) The system can be installed and used as a laboratory or industrial application system. The method processed can process the image of the fabric and is divided into four steps: acquiring a relative image from the sample of the woven fabric, obtaining a gray image and then the segmentation of the warp and weft from the fabric based on fast Fourier transform and inverse fast Fourier transform, calculation of the distance of the warp or weft sets by gray projection method and character shrinkage of the woven fabric by the average distance, coefficient of variation of distance and so on. Experimental results on virtual and physical woven fabrics indicated that the method provided could obtain the shrinkage information of woven fabric in detail. The method was programmed by Matlab software, and a graphical user interface was built by Delphi. The program has potential for practical use in the textile industry.

Physics of direct-contact ultrasonic cloth drying process

DOE PAGES

Peng, Chang; Ravi, Saitej; Patel, Viral K.; ...

2017-02-27

Existing methods of drying fabrics involve energy-intensive thermal evaporation of moisture from clothes. Drying fabrics using high-frequency vibrations of piezoelectric transducers can substantially reduce drying time and energy consumption. In this method, vibrational energy generates instability on the liquid-air interface and mechanically ejects water from a wet fabric. For the first time, the physics of the ultrasonic fabric drying process in direct-contact mode is studied. The kinematic and thermal responses of water droplets and fabrics on piezoelectric crystal transducers and metal mesh–based transducers are studied. The results suggest that on piezoelectric crystal transducers, the response of a droplet subjected tomore » ultrasonic excitation is dictated by the relative magnitude of the surface tension and the ultrasonic excitation forces. The drying process for a fabric on the studied transducers consists of two regimes—vibrational and thermal. When the water content is high, the vibrational forces can eject bulk water rapidly. But the more strongly bound water within the smaller fabric pores evaporates by the thermal energy generated as a result of the viscous losses. Our study finds that a metal mesh–based transducer is more suitable for dewatering fabrics, as it facilitates the ejection of water from the fabric–transducer interface to the opposite side of the mesh. A demonstration unit developed consumes 10–20% of the water latent heat energy at water contents greater than 20%.« less

Physics of direct-contact ultrasonic cloth drying process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peng, Chang; Ravi, Saitej; Patel, Viral K.

Existing methods of drying fabrics involve energy-intensive thermal evaporation of moisture from clothes. Drying fabrics using high-frequency vibrations of piezoelectric transducers can substantially reduce drying time and energy consumption. In this method, vibrational energy generates instability on the liquid-air interface and mechanically ejects water from a wet fabric. For the first time, the physics of the ultrasonic fabric drying process in direct-contact mode is studied. The kinematic and thermal responses of water droplets and fabrics on piezoelectric crystal transducers and metal mesh–based transducers are studied. The results suggest that on piezoelectric crystal transducers, the response of a droplet subjected tomore » ultrasonic excitation is dictated by the relative magnitude of the surface tension and the ultrasonic excitation forces. The drying process for a fabric on the studied transducers consists of two regimes—vibrational and thermal. When the water content is high, the vibrational forces can eject bulk water rapidly. But the more strongly bound water within the smaller fabric pores evaporates by the thermal energy generated as a result of the viscous losses. Our study finds that a metal mesh–based transducer is more suitable for dewatering fabrics, as it facilitates the ejection of water from the fabric–transducer interface to the opposite side of the mesh. A demonstration unit developed consumes 10–20% of the water latent heat energy at water contents greater than 20%.« less

Fabrication of multilayered conductive polymer structures via selective visible light photopolymerization

NASA Astrophysics Data System (ADS)

Cullen, Andrew T.; Price, Aaron D.

2017-04-01

Electropolymerization of pyrrole is commonly employed to fabricate intrinsically conductive polymer films that exhibit desirable electromechanical properties. Due to their monolithic nature, electroactive polypyrrole films produced via this process are typically limited to simple linear or bending actuation modes, which has hindered their application in complex actuation tasks. This initiative aims to develop the specialized fabrication methods and polymer formulations required to realize three-dimensional conductive polymer structures capable of more elaborate actuation modes. Our group has previously reported the application of the digital light processing additive manufacturing process for the fabrication of three-dimensional conductive polymer structures using ultraviolet radiation. In this investigation, we further expand upon this initial work and present an improved polymer formulation designed for digital light processing additive manufacturing using visible light. This technology enables the design of novel electroactive polymer sensors and actuators with enhanced capabilities and brings us one step closer to realizing more advanced electroactive polymer enabled devices.

Using rapid infrared forming to control interfaces in titanium-matrix composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warrier, S.G.; Lin, R.Y.

1993-03-01

Control of the fiber-matrix reaction during composite fabrication is commonly achieved by shortening the processing time, coating the reinforcement with relatively inert materials, or adding alloying elements to retard the reaction. To minimize the processing time, a rapid IR forming (RIF) technique for metal-matrix composite fabrication has been developed. Experiments have shown that the RIF technique is a quick, simple, and low-cost process to fabricate titanium-alloy matrix composites reinforced with either silicon carbide or carbon fibers. Due to short processing times (typically on the order of 1-2 minutes in an inert atmosphere for composites with up to eight-ply reinforcements), themore » interfacial reaction is limited and well controlled. Composites fabricated by this technique have mechanical properties that are comparable to (in several cases, superior to) those made with conventional diffusion-bonding techniques. 21 refs.« less

Preparation of highly hydrophobic cotton fabrics by modification with bifunctional silsesquioxanes in the sol-gel process

NASA Astrophysics Data System (ADS)

Przybylak, Marcin; Maciejewski, Hieronim; Dutkiewicz, Agnieszka

2016-11-01

The surface modification of cotton fabrics was carried out using two types of bifunctional fluorinated silsesquioxanes with different ratios of functional groups. The modification was performed either by one- or two-step process. Two methods, the sol-gel and the dip coating method were used in different configurations. The heat treatment and the washing process were applied after modification. The wettability of cotton fabric was evaluated by measuring water contact angles (WCA). Changes in the surface morphology were examined by scanning electron microscopy (SEM, SEM-LFD) and atomic force microscopy (AFM). Moreover, the modified fabrics were subjected to analysis of elemental composition of the applied coatings using SEM-EDS techniques. Highly hydrophobic textiles were obtained in all cases studied and one of the modifications resulted in imparting superhydrophobic properties. Most of impregnated textiles remained hydrophobic even after multiple washing process which shows that the studied modification is durable.

Solution-Processable High-Purity Semiconducting SWCNTs for Large-Area Fabrication of High-Performance Thin-Film Transistors.

PubMed

Gu, Jianting; Han, Jie; Liu, Dan; Yu, Xiaoqin; Kang, Lixing; Qiu, Song; Jin, Hehua; Li, Hongbo; Li, Qingwen; Zhang, Jin

2016-09-01

For the large-area fabrication of thin-film transistors (TFTs), a new conjugated polymer poly[9-(1-octylonoyl)-9H-carbazole-2,7-diyl] is developed to harvest ultrahigh-purity semiconducting single-walled carbon nanotubes. Combined with spectral and nanodevice characterization, the purity is estimated up to 99.9%. High density and uniform network formed by dip-coating process is liable to fabricate high-performance TFTs on a wafer-scale and the as-fabricated TFTs exhibit a high degree of uniformity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabricating Copper Nanotubes by Electrodeposition

NASA Technical Reports Server (NTRS)

Yang, E. H.; Ramsey, Christopher; Bae, Youngsam; Choi, Daniel

2009-01-01

Copper tubes having diameters between about 100 and about 200 nm have been fabricated by electrodeposition of copper into the pores of alumina nanopore membranes. Copper nanotubes are under consideration as alternatives to copper nanorods and nanowires for applications involving thermal and/or electrical contacts, wherein the greater specific areas of nanotubes could afford lower effective thermal and/or electrical resistivities. Heretofore, copper nanorods and nanowires have been fabricated by a combination of electrodeposition and a conventional expensive lithographic process. The present electrodeposition-based process for fabricating copper nanotubes costs less and enables production of copper nanotubes at greater rate.

Experiments Related to the Fabrication of Carbon Fiber/AMB-21 Polyimide Composite Tubes Using the RTM Process

NASA Technical Reports Server (NTRS)

Exum, Daniel

1996-01-01

AMB-21 is a new polymer developed by Mr. Ray Vannucci, NASA, LeRC as a noncarcinogenic polyimide matrix which may be suitable for fabricating composite parts by the Resin Transfer Modeling (RTM) process. The polyimide for this project was prepared at the Center of Composite Materials Research at N.C. A&T State University because it is not currently an item of commerce. The RTM process is especially suitable for producing geometrically complex composite parts at a low cost. Because of the high melting point and very high viscosity at the time of processing, polyimides have not been extensively used in the RTM process. The process for preparing AMB-21 as well as the process for fabricating composite plates will be described. The basic fabrication process consists of injecting a solvent solution of AMP-21 into a carbon fiber preform, evaporating the solvent, imidizing the polyimide, and vacuum/compression modeling the impregnated preform. All the above molding steps are preformed in a specially designed RTM mold which will be described. The results of this process have been inconsistent. Where as some experiments have resulted in a reasonably sound panels, others have not. Further refinements of the process are required to establish a reliable process.

Fabrication of magnetic bubble memory overlay

NASA Technical Reports Server (NTRS)

1973-01-01

Self-contained magnetic bubble memory overlay is fabricated by process that employs epitaxial deposition to form multi-layered complex of magnetically active components on single chip. Overlay fabrication comprises three metal deposition steps followed by subtractive etch.

Deformational Features and Microstructure Evolution of Copper Fabricated by a Single Pass of the Elliptical Cross-Section Spiral Equal-Channel Extrusion (ECSEE) Process

NASA Astrophysics Data System (ADS)

Wang, Chengpeng; Li, Fuguo; Liu, Juncheng

2018-04-01

The objectives of this work are to study the deformational feature, textures, microstructures, and dislocation configurations of ultrafine-grained copper processed by the process of elliptical cross-section spiral equal-channel extrusion (ECSEE). The deformation patterns of simple shear and pure shear in the ECSEE process were evaluated with the analytical method of geometric strain. The influence of the main technical parameters of ECSEE die on the effective strain distribution on the surface of ECSEE-fabricated samples was examined by the finite element simulation. The high friction factor could improve the effective strain accumulation of material deformation. Moreover, the pure copper sample fabricated by ECSEE ion shows a strong rotated cube shear texture. The refining mechanism of the dislocation deformation is dominant in copper processed by a single pass of ECSEE. The inhomogeneity of the micro-hardness distribution on the longitudinal section of the ECSEE-fabricated sample is consistent with the strain and microstructure distribution features.

Development of the weld-braze joining process

NASA Technical Reports Server (NTRS)

Bales, T. T.; Royster, D. M.; Arnold, W. E., Jr.

1973-01-01

A joining process, designated weld-brazing, was developed which combines resistance spot welding and brazing. Resistance spot welding is used to position and aline the parts, as well as to establish a suitable faying-surface gap for brazing. Fabrication is then completed at elevated temperature by capillary flow of the braze alloy into the joint. The process was used successfully to fabricate Ti-6Al-4V alloy joints by using 3003 aluminum braze alloy and should be applicable to other metal-braze systems. Test results obtained on single-overlap and hat-stiffened panel specimens show that weld-brazed joints were superior in tensile shear, stress rupture, fatigue, and buckling compared with joints fabricated by conventional means. Another attractive feature of the process is that the brazed joint is hermetically sealed by the braze material, which may eliminate many of the sealing problems encountered with riveted or spot welded structures. The relative ease of fabrication associated with the weld-brazing process may make it cost effective over conventional joining techniques.

Project delay analysis of HRSG

NASA Astrophysics Data System (ADS)

Silvianita; Novega, A. S.; Rosyid, D. M.; Suntoyo

2017-08-01

Completion of HRSG (Heat Recovery Steam Generator) fabrication project sometimes is not sufficient with the targeted time written on the contract. The delay on fabrication process can cause some disadvantages for fabricator, including forfeit payment, delay on HRSG construction process up until HRSG trials delay. In this paper, the author is using semi quantitative on HRSG pressure part fabrication delay with configuration plant 1 GT (Gas Turbine) + 1 HRSG + 1 STG (Steam Turbine Generator) using bow-tie analysis method. Bow-tie analysis method is a combination from FTA (Fault tree analysis) and ETA (Event tree analysis) to develop the risk matrix of HRSG. The result from FTA analysis is use as a threat for preventive measure. The result from ETA analysis is use as impact from fabrication delay.

Investigation of radiation keeping property of barite coated cloth via image processing method

NASA Astrophysics Data System (ADS)

Kilinçarslan, Ş.; Akkurt, İ.; Molla, T.; Akarslan, F.

2012-09-01

Preservative clothes which are able to absorb radiation beam are needed not only for saving people working at radioactive environment but also for saving others from natural and man-made radiation sources we are exposed in daily life. Barite is a mineral which can be used for armour plating because of high atomic numbered element barium constituent of barite. In this study, armour plating property of barite was applied to fabrics. Barite coated fabric having characteristic of keeping radiation was obtained by penetrating barite on cloth via coating method. Radiation keeping property of fabrics obtained was determined via image processing. The results of experiments showed that barite coated fabrics have blocked radiation more than normal fabrics have done.

Fabrication of absorption gratings with X-ray lithography for X-ray phase contrast imaging

NASA Astrophysics Data System (ADS)

Wang, Bo; Wang, Yu-Ting; Yi, Fu-Ting; Zhang, Tian-Chong; Liu, Jing; Zhou, Yue

2018-05-01

Grating-based X-ray phase contrast imaging is promising especially in the medical area. Two or three gratings are involved in grating-based X-ray phase contrast imaging in which the absorption grating of high-aspect-ratio is the most important device and the fabrication process is a great challenge. The material with large atomic number Z is used to fabricate the absorption grating for excellent absorption of X-ray, and Au is usually used. The fabrication process, which involves X-ray lithography, development and gold electroplating, is described in this paper. The absorption gratings with 4 μm period and about 100 μm height are fabricated and the high-aspect-ratio is 50.

Development of lightweight graphite/polyimide sandwich panels, phases 3, 4 and 5

NASA Technical Reports Server (NTRS)

Merlette, J. B.

1972-01-01

Work performed in the last three phases of the program included: (1) face sheet processing; (2) honeycomb core manufacture; (3) face sheet-to-core bonding development; and (4) sandwich panel fabrication and testing. Resin cure studies were a major portion of this effort since processing problems traced to the polyimide matrix resin had to be resolved before quality core and face sheets could be fabricated. Honeycomb core fabrication and testing were conducted by Hexcel Corporation. A total of four graphite/polyimide resin composite cores were fabricated, tested, and reported. Two sandwich panels weighing .48 and .58 lb/sq ft, respectively were designed and fabricated which meet the support structure loads for the shuttle orbiter thermal protection system.

Comparison of denture base adaptation between CAD-CAM and conventional fabrication techniques.

PubMed

Goodacre, Brian J; Goodacre, Charles J; Baba, Nadim Z; Kattadiyil, Mathew T

2016-08-01

Currently no data comparing the denture base adaptation of CAD-CAM and conventional denture processing techniques have been reported. The purpose of this in vitro study was to compare the denture base adaptation of pack and press, pour, injection, and CAD-CAM techniques for fabricating dentures to determine which process produces the most accurate and reproducible adaptation. A definitive cast was duplicated to create 40 gypsum casts that were laser scanned before any fabrication procedures were initiated. A master denture was made using the CAD-CAM process and was then used to create a putty mold for the fabrication of 30 standardized wax festooned dentures, 10 for each of the conventional processing techniques (pack and press, pour, injection). Scan files from 10 casts were sent to Global Dental Science, LLC for fabrication of the CAD-CAM test specimens. After specimens for each of the 4 techniques had been fabricated, they were hydrated for 24 hours and the intaglio surface laser scanned. The scan file of each denture was superimposed on the scan file of the corresponding preprocessing cast using surface matching software. Measurements were made at 60 locations, providing evaluation of fit discrepancies at the following areas: apex of the denture border, 6 mm from the denture border, crest of the ridge, palate, and posterior palatal seal. The use of median and interquartile range was used to assess accuracy and reproducibility. The Levine and Kruskal-Wallis analysis of variance was used to evaluate differences between processing techniques at the 5 specified locations (α=.05). The ranking of results based on median and interquartile range determined that the accuracy and reproducibility of the CAD-CAM technique was more consistently localized around zero at 3 of the 5 locations. Therefore, the CAD-CAM technique showed the best combination of accuracy and reproducibility among the tested fabrication techniques. The pack and press technique was more accurate at 2 of the 5 locations; however, its interquartile range (reproducibility) was the greatest of the 4 tested processing techniques. The pour technique was the most reproducible at 2 of the 5 locations; however, its accuracy was the lowest of the tested techniques. The CAD-CAM fabrication process was the most accurate and reproducible denture fabrication technique when compared with pack and press, pour, and injection denture base processing techniques. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Indirect three-dimensional printing of synthetic polymer scaffold based on thermal molding process.

PubMed

Park, Jeong Hun; Jung, Jin Woo; Kang, Hyun-Wook; Cho, Dong-Woo

2014-06-01

One of the major issues in tissue engineering has been the development of three-dimensional (3D) scaffolds, which serve as a structural template for cell growth and extracellular matrix formation. In scaffold-based tissue engineering, 3D printing (3DP) technology has been successfully applied for the fabrication of complex 3D scaffolds by using both direct and indirect techniques. In principle, direct 3DP techniques rely on the straightforward utilization of the final scaffold materials during the actual scaffold fabrication process. In contrast, indirect 3DP techniques use a negative mold based on a scaffold design, to which the desired biomaterial is cast and then sacrificed to obtain the final scaffold. Such indirect 3DP techniques generally impose a solvent-based process for scaffold fabrication, resulting in a considerable increase in the fabrication time and poor mechanical properties. In addition, the internal architecture of the resulting scaffold is affected by the properties of the biomaterial solution. In this study, we propose an advanced indirect 3DP technique using projection-based micro-stereolithography and an injection molding system (IMS) in order to address these challenges. The scaffold was fabricated by a thermal molding process using IMS to overcome the limitation of the solvent-based molding process in indirect 3DP techniques. The results indicate that the thermal molding process using an IMS has achieved a substantial reduction in scaffold fabrication time and has also provided the scaffold with higher mechanical modulus and strength. In addition, cell adhesion and proliferation studies have indicated no significant difference in cell activity between the scaffolds prepared by solvent-based and thermal molding processes.

Optimized micromirror arrays for adaptive optics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michalicek, M. Adrian

This paper describes the design, layout, fabrication, and surface characterization of highly optimized surface micromachined micromirror devices. Design considerations and fabrication capabilities are presented. These devices are fabricated in the state-of-the-art, four-level, planarized, ultra-low-stress polysilicon process available at Sandia National Laboratories known as the Sandia Ultra-planar Multi-level MEMS Technology (SUMMiT). This enabling process permits the development of micromirror devices with near-ideal characteristics that have previously been unrealizable in standard three-layer polysilicon processes. The reduced 1 {mu}m minimum feature sizes and 0.1 {mu}m mask resolution make it possible to produce dense wiring patterns and irregularly shaped flexures. Likewise, mirror surfaces canmore » be uniquely distributed and segmented in advanced patterns and often irregular shapes in order to minimize wavefront error across the pupil. The ultra-low-stress polysilicon and planarized upper layer allow designers to make larger and more complex micromirrors of varying shape and surface area within an array while maintaining uniform performance of optical surfaces. Powerful layout functions of the AutoCAD editor simplify the design of advanced micromirror arrays and make it possible to optimize devices according to the capabilities of the fabrication process. Micromirrors fabricated in this process have demonstrated a surface variance across the array from only 2{endash}3 nm to a worst case of roughly 25 nm while boasting active surface areas of 98{percent} or better. Combining the process planarization with a {open_quotes}planarized-by-design{close_quotes} approach will produce micromirror array surfaces that are limited in flatness only by the surface deposition roughness of the structural material. Ultimately, the combination of advanced process and layout capabilities have permitted the fabrication of highly optimized micromirror arrays for adaptive optics. {copyright} {ital 1999 American Institute of Physics.}« less

Experimental studies on a novel roll-to-roll powder hot embossing for large-area fabrication of micropyramid arrays on polymers

NASA Astrophysics Data System (ADS)

Yi, Peiyun; Deng, Yujun; Shu, Yunyi; Peng, Linfa

2018-08-01

Roll-to-roll (R2R) hot embossing is regarded as a cost-effective replication technology to fabricate microstructures on polymer films. However, the characteristics of continuous and fast forming for the R2R hot embossing process limits material flow during the filling stage and results in significant springback during the demolding stage. To resolve this issue, this study proposed a novel R2R powder hot embossing process, which combines the merits of the continuous fabrication of R2R hot embossing and near-net-shape forming of powder sintering and also decreases the whole cycle of the fabrication from films to microstructures. First, the relation between the molten layer thickness and processing parameters was discussed and an analytical model was established to predict the feed of the polymeric powder during R2R powder hot embossing. Then, with the use of a micro-pyramid array mold, the impact of the process parameters including mold temperature, feeding speed and applied force on the geometrical dimension of the patterned microstructures was discussed. Last, based on the response surface analysis, a process window, in terms of the mold temperature of 132 °C –145 °C, feeding speed of 0.1–1.4 m min‑1 and applied force of 15–50 kgf was determined for the continuous fabrication of completely-filled micropyramid arrays with the R2R powder hot embossing process. This research demonstrated the feasibility and superiority of the proposed R2R powder hot embossing process in continuously fabricating micropatterned structures on polymeric films.

Magma transport in sheet intrusions of the Alnö carbonatite complex, central Sweden.

PubMed

Andersson, Magnus; Almqvist, Bjarne S G; Burchardt, Steffi; Troll, Valentin R; Malehmir, Alireza; Snowball, Ian; Kübler, Lutz

2016-06-10

Magma transport through the Earth's crust occurs dominantly via sheet intrusions, such as dykes and cone-sheets, and is fundamental to crustal evolution, volcanic eruptions and geochemical element cycling. However, reliable methods to reconstruct flow direction in solidified sheet intrusions have proved elusive. Anisotropy of magnetic susceptibility (AMS) in magmatic sheets is often interpreted as primary magma flow, but magnetic fabrics can be modified by post-emplacement processes, making interpretation of AMS data ambiguous. Here we present AMS data from cone-sheets in the Alnö carbonatite complex, central Sweden. We discuss six scenarios of syn- and post-emplacement processes that can modify AMS fabrics and offer a conceptual framework for systematic interpretation of magma movements in sheet intrusions. The AMS fabrics in the Alnö cone-sheets are dominantly oblate with magnetic foliations parallel to sheet orientations. These fabrics may result from primary lateral flow or from sheet closure at the terminal stage of magma transport. As the cone-sheets are discontinuous along their strike direction, sheet closure is the most probable process to explain the observed AMS fabrics. We argue that these fabrics may be common to cone-sheets and an integrated geology, petrology and AMS approach can be used to distinguish them from primary flow fabrics.

Magma transport in sheet intrusions of the Alnö carbonatite complex, central Sweden

PubMed Central

Andersson, Magnus; Almqvist, Bjarne S. G.; Burchardt, Steffi; Troll, Valentin R.; Malehmir, Alireza; Snowball, Ian; Kübler, Lutz

2016-01-01

Magma transport through the Earth’s crust occurs dominantly via sheet intrusions, such as dykes and cone-sheets, and is fundamental to crustal evolution, volcanic eruptions and geochemical element cycling. However, reliable methods to reconstruct flow direction in solidified sheet intrusions have proved elusive. Anisotropy of magnetic susceptibility (AMS) in magmatic sheets is often interpreted as primary magma flow, but magnetic fabrics can be modified by post-emplacement processes, making interpretation of AMS data ambiguous. Here we present AMS data from cone-sheets in the Alnö carbonatite complex, central Sweden. We discuss six scenarios of syn- and post-emplacement processes that can modify AMS fabrics and offer a conceptual framework for systematic interpretation of magma movements in sheet intrusions. The AMS fabrics in the Alnö cone-sheets are dominantly oblate with magnetic foliations parallel to sheet orientations. These fabrics may result from primary lateral flow or from sheet closure at the terminal stage of magma transport. As the cone-sheets are discontinuous along their strike direction, sheet closure is the most probable process to explain the observed AMS fabrics. We argue that these fabrics may be common to cone-sheets and an integrated geology, petrology and AMS approach can be used to distinguish them from primary flow fabrics. PMID:27282420

Inhibition of enamel demineralisation using "Nd-YAG and diode laser assisted fluoride therapy".

PubMed

Chand, B R; Kulkarni, S; Mishra, P

2016-02-01

This in vitro study was to evaluate the irradiation efficacy of the Diode laser and the Nd-YAG laser either un-assisted or assisted by acidulated phosphate fluoride (APF) treatment on enamel's acid resistance. Seventy-two enamel samples, obtained from 12 extracted human molars, were randomly assigned to 6 groups as follows: (1) Control (C); (2) Exposed to APF gel (F); (3) Diode laser (DL); (4) Irradiated with Diode laser through APF gel (DL/F); (5) Nd-YAG laser (NL) and (6) Irradiated with Nd-YAG laser through APF gel (NL/F). The specimens were individually demineralised in an acidified hydroxyethylcellulose system, and the acid resistance was evaluated by determining the calcium ion dissolution using atomic absorption spectrometry. The average concentration of the calcium ion determined in groups 1 to 6 was 901, 757, 736, 592, 497 and 416 parts per million micrograms/gram, respectively. The results showed that demineralisation in the NL/F group was significantly less than the other groups and the control group was significantly greater than the other groups (P < 0.001). The effect of Nd-YAG laser irradiation, used alone or in combination with APF, in decreasing the enamel demineralisation was greater than all the other groups.

Fabrication of tungsten wire reinforced nickel-base alloy composites

NASA Technical Reports Server (NTRS)

Brentnall, W. D.; Toth, I. J.

1974-01-01

Fabrication methods for tungsten fiber reinforced nickel-base superalloy composites were investigated. Three matrix alloys in pre-alloyed powder or rolled sheet form were evaluated in terms of fabricability into composite monotape and multi-ply forms. The utility of monotapes for fabricating more complex shapes was demonstrated. Preliminary 1093C (2000F) stress rupture tests indicated that efficient utilization of fiber strength was achieved in composites fabricated by diffusion bonding processes. The fabrication of thermal fatigue specimens is also described.

Bonded polyimide fuel cell package

DOEpatents

Morse, Jeffrey D.; Jankowski, Alan; Graff, Robert T.; Bettencourt, Kerry

2010-06-08

Described herein are processes for fabricating microfluidic fuel cell systems with embedded components in which micron-scale features are formed by bonding layers of DuPont Kapton.TM. polyimide laminate. A microfluidic fuel cell system fabricated using this process is also described.

Performance of resin transfer molded multiaxial warp knit composites

NASA Technical Reports Server (NTRS)

Dexter, H. Benson; Hasko, Gregory H.

1993-01-01

Composite materials that are subjected to complex loads have traditionally been fabricated with multidirectionally oriented prepreg tape materials. Some of the problems associated with this type of construction include low delamination resistance, poor out-of-plane strength, and labor intensive fabrication processes. Textile reinforced composites with through-the-thickness reinforcement have the potential to solve some of these problems. Recently, a relatively new class of noncrimp fabrics designated as multiaxial warp knits have been developed to minimize some of the high cost and damage tolerance concerns. Multiple stacks of warp knit fabrics can be knitted or stitched together to reduce layup labor cost. The through-the-thickness reinforcement can provide significant improvements in damage tolerance and out-of-plane strength. Multilayer knitted/stitched preforms, in conjunction with resin transfer molding (RTM), offer potential for significant cost savings in fabrication of primary aircraft structures. The objectives of this investigation were to conduct RTM processing studies and to characterize the mechanical behavior of composites reinforced with three multiaxial warp knit fabrics. The three fabrics investigated were produced by Hexcel and Milliken in the United States, and Saerbeck in Germany. Two resin systems, British Petroleum E9O5L and 3M PR 500, were characterized for RTM processing. The performance of Hexcel and Milliken quasi-isotropic knitted fabrics are compared to conventional prepreg tape laminates. The performance of the Saerbeck fabric is compared to uniweave wing skin layups being investigated by Douglas Aircraft Company in the NASA Advanced Composites Technology (ACT) program. Tests conducted include tension, open hole tension, compression, open hole compression, and compression after impact. The effects of fabric defects, such as misaligned fibers and gaps between tows, on material performance are also discussed. Estimated material and labor cost savings are projected for the Saerbeck fabric as compared to uniweave fabric currently being used by Douglas in the NASA ACT wing development program.

Processing Science of Epoxy Resin Composites

DTIC Science & Technology

1984-01-15

3 2.2 LAMINATE FABRICATION 30 2.2.1 Baseline Laminate Fabrication 30 2.2.2 Large Laminate Fabrication 36 2.3 DIFFUSIVITY AND SOLUBILITY...Thick Laminate 42 28 Baseline Cure Cycle With Specimen Advancement Levels 45 29 Composite Panel Fabrication 47 30 Composite Panel Fabrication 48 31...first change was the elimination of the different 1 resin formulations and concentration on the normal or baseline 5208/T300 prepreg as produced by

Bottom-up fabrication of paper-based microchips by blade coating of cellulose microfibers on a patterned surface.

PubMed

Gao, Bingbing; Liu, Hong; Gu, Zhongze

2014-12-23

We report a method for the bottom-up fabrication of paper-based capillary microchips by the blade coating of cellulose microfibers on a patterned surface. The fabrication process is similar to the paper-making process in which an aqueous suspension of cellulose microfibers is used as the starting material and is blade-coated onto a polypropylene substrate patterned using an inkjet printer. After water evaporation, the cellulose microfibers form a porous, hydrophilic, paperlike pattern that wicks aqueous solution by capillary action. This method enables simple, fast, inexpensive fabrication of paper-based capillary channels with both width and height down to about 10 μm. When this method is used, the capillary microfluidic chip for the colorimetric detection of glucose and total protein is fabricated, and the assay requires only 0.30 μL of sample, which is 240 times smaller than for paper devices fabricated using photolithography.

Rapid fabrication of surface-relief plastic diffusers by ultrasonic embossing

NASA Astrophysics Data System (ADS)

Liu, Shih-Jung; Huang, Yu-Chin; Yang, Sen-Yeu; Hsieh, Kuo-Huang

2010-07-01

This paper discusses an innovative and effective ultrasonic embossing process, which enables the rapid fabrication of surface-relief plastic diffusers. The metallic mold bearing the microstructures is fabricated using a tungsten carbide turning machine. A 1500-W ultrasonic vibrator with an output frequency of 20 kHz was used to replicate the microstructure onto 1-mm-thick PMMA plates in the experiments. During ultrasonic embossing, the ultrasonic energy is converted into heat through intermolecular friction at the master mold/plastic plate interface due to asperities to melt the thermoplastic at the interface and thereby to replicate the microstructure. Under the proper processing conditions, high-performance plastic diffusers have been successfully fabricated. The cycle time required to successfully fabricate a diffuser is less than 2 s. The experimental results suggest that ultrasonic embossing could provide an effective way of fabricating high-performance plastic diffusers with a high throughput.

Smart fabrics: integrating fiber optic sensors and information networks.

PubMed

El-Sherif, Mahmoud

2004-01-01

"Smart Fabrics" are defined as fabrics capable of monitoring their own "health", and sensing environmental conditions. They consist of special type of sensors, signal processing, and communication network embedded into textile substrate. Available conventional sensors and networking systems are not fully technologically mature for such applications. New classes of miniature sensors, signal processing and networking systems are urgently needed for such application. Also, the methodology for integration into textile structures has to be developed. In this paper, the development of smart fabrics with embedded fiber optic systems is presented for applications in health monitoring and diagnostics. Successful development of such smart fabrics with embedded sensors and networks is mainly dependent on the development of the proper miniature sensors technology, and on the integration of these sensors into textile structures. The developed smart fabrics will be discussed and samples of the results will be presented.

Fabrication of lightweight Si/SiC LIDAR mirrors

NASA Technical Reports Server (NTRS)

Goela, Jitendra S.; Taylor, Raymond L.

1991-01-01

A new, chemical vapor deposition (CVD) process was developed for fabricating lightweight, polycrystalline silicon/silicon-carbide (Si/SiC) mirrors. The process involves three CVD steps: (1) to produce the mirror faceplate; (2) to form the lightweight backstructure, which is deposited integral to the faceplate; and (3) to deposit a layer of optical-grade material, e.g., Si, onto the front surface of the faceplate. The mirror figure and finish are fabricated into the faceplate.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yang; Zhao, Qiangsheng; Mirdamadi, Mansour

Woven fabric carbon fiber/epoxy composites made through compression molding are one of the promising choices of material for the vehicle light-weighting strategy. Previous studies have shown that the processing conditions can have substantial influence on the performance of this type of the material. Therefore the optimization of the compression molding process is of great importance to the manufacturing practice. An efficient way to achieve the optimized design of this process would be through conducting finite element (FE) simulations of compression molding for woven fabric carbon fiber/epoxy composites. However, performing such simulation remains a challenging task for FE as multiple typesmore » of physics are involved during the compression molding process, including the epoxy resin curing and the complex mechanical behavior of woven fabric structure. In the present study, the FE simulation of the compression molding process of resin based woven fabric composites at continuum level is conducted, which is enabled by the implementation of an integrated material modeling methodology in LS-Dyna. Specifically, the chemo-thermo-mechanical problem of compression molding is solved through the coupling of three material models, i.e., one thermal model for temperature history in the resin, one mechanical model to update the curing-dependent properties of the resin and another mechanical model to simulate the behavior of the woven fabric composites. Preliminary simulations of the carbon fiber/epoxy woven fabric composites in LS-Dyna are presented as a demonstration, while validations and models with real part geometry are planned in the future work.« less

Heavily Boron-Doped Silicon Layer for the Fabrication of Nanoscale Thermoelectric Devices

PubMed Central

Liu, Yang; Deng, Lingxiao; Zhang, Mingliang; Zhang, Shuyuan; Ma, Jing; Song, Peishuai; Liu, Qing; Ji, An; Yang, Fuhua; Wang, Xiaodong

2018-01-01

Heavily boron-doped silicon layers and boron etch-stop techniques have been widely used in the fabrication of microelectromechanical systems (MEMS). This paper provides an introduction to the fabrication process of nanoscale silicon thermoelectric devices. Low-dimensional structures such as silicon nanowire (SiNW) have been considered as a promising alternative for thermoelectric applications in order to achieve a higher thermoelectric figure of merit (ZT) than bulk silicon. Here, heavily boron-doped silicon layers and boron etch-stop processes for the fabrication of suspended SiNWs will be discussed in detail, including boron diffusion, electron beam lithography, inductively coupled plasma (ICP) etching and tetramethylammonium hydroxide (TMAH) etch-stop processes. A 7 μm long nanowire structure with a height of 280 nm and a width of 55 nm was achieved, indicating that the proposed technique is useful for nanoscale fabrication. Furthermore, a SiNW thermoelectric device has also been demonstrated, and its performance shows an obvious reduction in thermal conductivity. PMID:29385759

Investigation of Springback Associated with Composite Material Component Fabrication (MSFC Center Director's Discretionary Fund Final Report, Project 94-09)

NASA Technical Reports Server (NTRS)

Benzie, M. A.

1998-01-01

The objective of this research project was to examine processing and design parameters in the fabrication of composite components to obtain a better understanding and attempt to minimize springback associated with composite materials. To accomplish this, both processing and design parameters were included in a Taguchi-designed experiment. Composite angled panels were fabricated, by hand layup techniques, and the fabricated panels were inspected for springback effects. This experiment yielded several significant results. The confirmation experiment validated the reproducibility of the factorial effects, error recognized, and experiment as reliable. The material used in the design of tooling needs to be a major consideration when fabricating composite components, as expected. The factors dealing with resin flow, however, raise several potentially serious material and design questions. These questions must be dealt with up front in order to minimize springback: viscosity of the resin, vacuum bagging of the part for cure, and the curing method selected. These factors directly affect design, material selection, and processing methods.

Friction Freeform Fabrication of Superalloy Inconel 718: Prospects and Problems

NASA Astrophysics Data System (ADS)

Dilip, J. J. S.; Janaki Ram, G. D.

2014-01-01

Friction Freeform Fabrication is a new solid-state additive manufacturing process. The present investigation reports a detailed study on the prospects of this process for additive part fabrication in superalloy Inconel 718. Using a rotary friction welding machine and employing alloy 718 consumable rods in solution treated condition, cylindrical-shaped multi-layer friction deposits (10 mm diameter) were successfully produced. In the as-deposited condition, the deposits showed very fine grain size with no grain boundary δ phase. The deposits responded well to direct aging and showed satisfactory room-temperature tensile properties. However, their stress rupture performance was unsatisfactory because of their layered microstructure with very fine grain size and no grain boundary δ phase. The problem was overcome by heat treating the deposits first at 1353 K (1080 °C) (for increasing the grain size) and then at 1223 K (950 °C) (for precipitating the δ phase). Overall, the current study shows that Friction Freeform Fabrication is a very useful process for additive part fabrication in alloy 718.

The response of fabric variations to simple shear and migration recrystallization

DOE PAGES

Kennedy, Joseph H.; Pettit, Erin C.

2015-06-01

The observable microstructures in ice are the result of many dynamic and competing processes. These processes are influenced by climate variables in the firn. Layers deposited in different climate regimes may show variations in fabric which can persist deep into the ice sheet; fabric may 'remember' these past climate regimes. In this paper, we model the evolution of fabric variations below the firn–ice transition and show that the addition of shear to compressive-stress regimes preserves the modeled fabric variations longer than compression-only regimes, because shear drives a positive feedback between crystal rotation and deformation. Even without shear, the modeled icemore » retains memory of the fabric variation for ~200 ka in typical polar ice-sheet conditions. Our model shows that temperature affects how long the fabric variation is preserved, but only affects the strain-integrated fabric evolution profile when comparing results straddling the thermal-activation-energy threshold (~–10°C). Even at high temperatures, migration recrystallization does not eliminate the modeled fabric's memory under most conditions. High levels of nearest-neighbor interactions will, however, eliminate the modeled fabric's memory more quickly than low levels of nearest-neighbor interactions. Finally, our model predicts that fabrics will retain memory of past climatic variations when subject to a wide variety of conditions found in polar ice sheets.« less

Lithographic fabrication of nanoapertures

DOEpatents

Fleming, James G.

2003-01-01

A new class of silicon-based lithographically defined nanoapertures and processes for their fabrication using conventional silicon microprocessing technology have been invented. The new ability to create and control such structures should significantly extend our ability to design and implement chemically selective devices and processes.

Fabrication of large area woodpile structure in polymer

NASA Astrophysics Data System (ADS)

Gupta, Jaya Prakash; Dutta, Neilanjan; Yao, Peng; Sharkawy, Ahmed S.; Prather, Dennis W.

2009-02-01

A fabrication process of three-dimensional Woodpile photonic crystals based on multilayer photolithography from commercially available photo resist SU8 have been demonstrated. A 6-layer, 2 mm × 2mm woodpile has been fabricated. Different factors that influence the spin thickness on multiple resist application have been studied. The fabrication method used removes, the problem of intermixing, and is more repeatable and robust than the multilayer fabrication techniques for three dimensional photonic crystal structures that have been previously reported. Each layer is developed before next layer photo resist spin, instead of developing the whole structure in the final step as used in multilayer process. The desired thickness for each layer is achieved by the calibration of spin speed and use of different photo resist compositions. Deep UV exposure confinement has been the defining parameter in this process. Layer uniformity for every layer is independent of the previous developed layers and depends on the photo resist planarizing capability, spin parameters and baking conditions. The intermixing problem, which results from the previous layers left uncrossed linked photo resist, is completely removed in this process as the previous layers are fully developed, avoiding any intermixing between the newly spun and previous layers. Also this process gives the freedom to redo every spin any number of times without affecting the previously made structure, which is not possible in other multilayer process where intermediate developing is not performed.

Fabrication of High-Resolution Gamma-Ray Metallic Magnetic Calorimeters with Ag:Er Sensor and Thick Electroplated Absorbers

NASA Astrophysics Data System (ADS)

Hummatov, Ruslan; Hall, John A.; Kim, Geon-Bo; Friedrich, Stephan; Cantor, Robin; Boyd, S. T. P.

2018-05-01

We are developing metallic magnetic calorimeters for high-resolution gamma-ray spectroscopy for non-destructive assay of nuclear materials. Absorbers for these higher-energy photons can require substantial thickness to achieve adequate stopping power. We developed a new absorber fabrication process using dry-film photoresists to electroform cantilevered, thick absorbers. Gamma detectors with these absorbers have an energy resolution of 38 eV FWHM at 60 keV. In this report, we summarize modifications to STARCryo's "Delta 1000" process for our devices and describe the new absorber fabrication process.

Computer Aided Design of Computer Generated Holograms for electron beam fabrication

NASA Technical Reports Server (NTRS)

Urquhart, Kristopher S.; Lee, Sing H.; Guest, Clark C.; Feldman, Michael R.; Farhoosh, Hamid

1989-01-01

Computer Aided Design (CAD) systems that have been developed for electrical and mechanical design tasks are also effective tools for the process of designing Computer Generated Holograms (CGHs), particularly when these holograms are to be fabricated using electron beam lithography. CAD workstations provide efficient and convenient means of computing, storing, displaying, and preparing for fabrication many of the features that are common to CGH designs. Experience gained in the process of designing CGHs with various types of encoding methods is presented. Suggestions are made so that future workstations may further accommodate the CGH design process.

Consolidation of graphite thermoplastic textile preforms for primary aircraft structure

NASA Technical Reports Server (NTRS)

Suarez, J.; Mahon, J.

1991-01-01

The use of innovative cost effective material forms and processes is being considered for fabrication of future primary aircraft structures. Processes that have been identified as meeting these goals are textile preforms that use resin transfer molding (RTM) and consolidation forming. The Novel Composites for Wing and Fuselage Applications (NCWFA) program has as its objective the integration of innovative design concepts with cost effective fabrication processes to develop damage-tolerant structures that can perform at a design ultimate strain level of 6000 micro-inch/inch. In this on-going effort, design trade studies were conducted to arrive at advanced wing designs that integrate new material forms with innovative structural concepts and cost effective fabrication methods. The focus has been on minimizing part count (mechanical fasteners, clips, number of stiffeners, etc.), by using cost effective textile reinforcement concepts that provide improved damage tolerance and out-of-plane load capability, low-cost resin transfer molding processing, and thermoplastic forming concepts. The fabrication of representative Y spars by consolidation methods will be described. The Y spars were fabricated using AS4 (6K)/PEEK 150g commingled angle interlock 0/90-degree woven preforms with +45-degree commingled plies stitched using high strength Toray carbon thread and processed by autoclave consolidation.

Fabrication of Copper-Rich Cu-Al Alloy Using the Wire-Arc Additive Manufacturing Process

NASA Astrophysics Data System (ADS)

Dong, Bosheng; Pan, Zengxi; Shen, Chen; Ma, Yan; Li, Huijun

2017-12-01

An innovative wire-arc additive manufacturing (WAAM) process is used to fabricate Cu-9 at. pct Al on pure copper plates in situ, through separate feeding of pure Cu and Al wires into a molten pool, which is generated by the gas tungsten arc welding (GTAW) process. After overcoming several processing problems, such as opening the deposition molten pool on the extremely high-thermal conductive copper plate and conducting the Al wire into the molten pool with low feed speed, the copper-rich Cu-Al alloy was successfully produced with constant predesigned Al content above the dilution-affected area. Also, in order to homogenize the as-fabricated material and improve the mechanical properties, two further homogenization heat treatments at 1073 K (800 °C) and 1173 K (900 °C) were applied. The material and mechanical properties of as-fabricated and heat-treated samples were compared and analyzed in detail. With increased annealing temperatures, the content of precipitate phases decreased and the samples showed gradual improvements in both strength and ductility with little variation in microstructures. The present research opened a gate for in-situ fabrication of Cu-Al alloy with target chemical composition and full density using the additive manufacturing process.

Fabrication of Superconducting Detectors for Studying the Universe

NASA Technical Reports Server (NTRS)

Brown, Ari-David

2012-01-01

Superconducting detectors offer unparalleled means of making astronomical/cosmological observations. Fabrication of these detectors is somewhat unconventional; however, a lot of novel condensed matter physics/materials scientific discoveries and semiconductor fabrication processes can be generated in making these devices.

Fabrication of cast particle-reinforced metals via pressure infiltration

NASA Technical Reports Server (NTRS)

Klier, E. M.; Mortensen, A.; Cornie, J. A.; Flemings, M. C.

1991-01-01

A new casting process for fabrication of particle-reinforced metals is presented whereby a composite of particulate reinforcing phase in metal is first produced by pressure infiltration. This composite is then diluted in additional molten metal to obtain the desired reinforcement volume fraction and metal composition. This process produces a pore-free as-cast particulate metal-matrix composite. This process is demonstrated for fabrication of magnesium-matrix composites containing SiC reinforcements of average diameter 30, 10 and 3 microns. It is compared with the compocasting process, which was investigated as well for similar SiC particles in Mg-10 wt pct Al, and resulted in unacceptable levels of porosity in the as-cast composite.

Fabrication of thorium bearing carbide fuels

DOEpatents

Gutierrez, Rueben L.; Herbst, Richard J.; Johnson, Karl W. R.

1981-01-01

Thorium-uranium carbide and thorium-plutonium carbide fuel pellets have been fabricated by the carbothermic reduction process. Temperatures of 1750.degree. C. and 2000.degree. C. were used during the reduction cycle. Sintering temperatures of 1800.degree. C. and 2000.degree. C. were used to prepare fuel pellet densities of 87% and >94% of theoretical, respectively. The process allows the fabrication of kilogram quantities of fuel with good reproducibility of chemicals and phase composition. Methods employing liquid techniques that form carbide microspheres or alloying-techniques which form alloys of thorium-uranium or thorium-plutonium suffer from limitation on the quantities processed of because of criticality concerns and lack of precise control of process conditions, respectively.

Solar cells utilizing pulsed-energy crystallized microcrystalline/polycrystalline silicon

DOEpatents

Kaschmitter, J.L.; Sigmon, T.W.

1995-10-10

A process for producing multi-terminal devices such as solar cells wherein a pulsed high energy source is used to melt and crystallize amorphous silicon deposited on a substrate which is intolerant to high processing temperatures, whereby the amorphous silicon is converted into a microcrystalline/polycrystalline phase. Dopant and hydrogenation can be added during the fabrication process which provides for fabrication of extremely planar, ultra shallow contacts which results in reduction of non-current collecting contact volume. The use of the pulsed energy beams results in the ability to fabricate high efficiency microcrystalline/polycrystalline solar cells on the so-called low-temperature, inexpensive plastic substrates which are intolerant to high processing temperatures.

Solar cells utilizing pulsed-energy crystallized microcrystalline/polycrystalline silicon

DOEpatents

Kaschmitter, James L.; Sigmon, Thomas W.

1995-01-01

A process for producing multi-terminal devices such as solar cells wherein a pulsed high energy source is used to melt and crystallize amorphous silicon deposited on a substrate which is intolerant to high processing temperatures, whereby to amorphous silicon is converted into a microcrystalline/polycrystalline phase. Dopant and hydrogenization can be added during the fabrication process which provides for fabrication of extremely planar, ultra shallow contacts which results in reduction of non-current collecting contact volume. The use of the pulsed energy beams results in the ability to fabricate high efficiency microcrystalline/polycrystalline solar cells on the so-called low-temperature, inexpensive plastic substrates which are intolerant to high processing temperatures.

Pad ultrasonic batch dyeing of causticized lyocell fabric with reactive dyes.

PubMed

Babar, Aijaz Ahmed; Peerzada, Mazhar Hussain; Jhatial, Abdul Khalique; Bughio, Noor-Ul-Ain

2017-01-01

Conventionally, cellulosic fabric dyed with reactive dyes requires significant amount of salt. However, the dyeing of a solvent spun regenerated cellulosic fiber is a critical process. This paper presents the dyeing results of lyocell fabrics dyed with conventional pad batch (CPB) and pad ultrasonic batch (PUB) processes. The dyeing of lyocell fabrics was carried out with two commercial dyes namely Drimarine Blue CL-BR and Ramazol Blue RGB. Dyeing parameters including concentration of sodium hydroxide, sodium carbonate and dwell time were compared for the two processes. The outcomes show that PUB dyed samples offered reasonably higher color yield and dye fixation than CPB dyed samples. A remarkable reduction of 12h in batching time, 18ml/l in NaOH and 05g/l in Na 2 CO 3 quantity was observed for PUB processed samples producing similar results compared to CPB process, making PUB a more economical, productive and an environment friendly process. Color fastness examination witnessed identical results for both PUB and CPB methods. No significant change in surface morphology of PUB processed samples was observed through scanning electron microscope (SEM) analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

Combined fabrication process for high-precision aspheric surface based on smoothing polishing and magnetorheological finishing

NASA Astrophysics Data System (ADS)

Nie, Xuqing; Li, Shengyi; Song, Ci; Hu, Hao

2014-08-01

Due to the different curvature everywhere, the aspheric surface is hard to achieve high-precision accuracy by the traditional polishing process. Controlling of the mid-spatial frequency errors (MSFR), in particular, is almost unapproachable. In this paper, the combined fabrication process based on the smoothing polishing (SP) and magnetorheological finishing (MRF) is proposed. The pressure distribution of the rigid polishing lap and semi-flexible polishing lap is calculated. The shape preserving capacity and smoothing effect are compared. The feasibility of smoothing aspheric surface with the semi-flexible polishing lap is verified, and the key technologies in the SP process are discussed. Then, A K4 parabolic surface with the diameter of 500mm is fabricated based on the combined fabrication process. A Φ150 mm semi-flexible lap is used in the SP process to control the MSFR, and the deterministic MRF process is applied to figure the surface error. The root mean square (RMS) error of the aspheric surface converges from 0.083λ (λ=632.8 nm) to 0.008λ. The power spectral density (PSD) result shows that the MSFR are well restrained while the surface error has a great convergence.

Fabrication of Microfiber Patterns with Ivy Shoot-Like Geometries Using Improved Electrospinning

PubMed Central

Jeong, Young Hun; Lee, Jongwan

2016-01-01

Fibers and fibrous structures are used extensively in various fields due to their many advantages. Microfibers, as well as nanofibers, are considered to be some of the most valuable forms of advanced materials. Accordingly, various methods for fabricating microfibers have been developed. Electrospinning is a useful fabrication method for continuous polymeric nano- and microfibers with attractive merits. However, this technique has limitations in its ability to control the geometry of fibrous structures. Herein, advanced electrospinning with direct-writing functionality was used to fabricate microfiber patterns with ivy shoot-like geometries after experimentally investigating the effects of the process conditions on the fiber formation. The surface properties of the fibers were also modified by introducing nanoscale pores through the use of higher levels of humidity during the fabrication process. PMID:28773390

Fabrication of Microfiber Patterns with Ivy Shoot-Like Geometries Using Improved Electrospinning.

PubMed

Jeong, Young Hun; Lee, Jongwan

2016-04-01

Fibers and fibrous structures are used extensively in various fields due to their many advantages. Microfibers, as well as nanofibers, are considered to be some of the most valuable forms of advanced materials. Accordingly, various methods for fabricating microfibers have been developed. Electrospinning is a useful fabrication method for continuous polymeric nano- and microfibers with attractive merits. However, this technique has limitations in its ability to control the geometry of fibrous structures. Herein, advanced electrospinning with direct-writing functionality was used to fabricate microfiber patterns with ivy shoot-like geometries after experimentally investigating the effects of the process conditions on the fiber formation. The surface properties of the fibers were also modified by introducing nanoscale pores through the use of higher levels of humidity during the fabrication process.

Optical device fabrication using femtosecond laser processing with glass-hologram

NASA Astrophysics Data System (ADS)

Suzuki, Jun'ichi; Arima, Yasunori; Tanaka, Shuhei

2011-03-01

Using femtosecond laser processing with glass-hologram, fabrication of 1cm-long straight waveguide and X-coupler is reported in this paper. We design and fabricate 4-level glass-hologram which generates 1cm-long straight line intensity. We fabricate 1cm-long waveguides inside fused silica at one shot exposure with the glass-hologram. We investigate the waveguide performance of near field pattern and propagation loss at wavelength of 1550nm. The near field pattern is almost circular shape. The propagation loss at 1550nm is estimated to be < 1.0 dB/cm. As an example of an optical device consisting of straight waveguides, we fabricate X-coupler or 2x2 coupler using straight line waveguides, and observe the output power ratio depending on crossing angle.

Investigation of radiation keeping property of barite coated cloth via image processing method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kilincarslan, S.; Akkurt, I.; Molla, T.

Preservative clothes which are able to absorb radiation beam are needed not only for saving people working at radioactive environment but also for saving others from natural and man-made radiation sources we are exposed in daily life. Barite is a mineral which can be used for armour plating because of high atomic numbered element barium constituent of barite. In this study, armour plating property of barite was applied to fabrics. Barite coated fabric having characteristic of keeping radiation was obtained by penetrating barite on cloth via coating method. Radiation keeping property of fabrics obtained was determined via image processing. Themore » results of experiments showed that barite coated fabrics have blocked radiation more than normal fabrics have done.« less

Analysis of roll-stamped light guide plate fabricated with laser-ablated stamper

NASA Astrophysics Data System (ADS)

Na, Hyunjun; Hong, Seokkwan; Kim, Jongsun; Hwang, Jeongho; Joo, Byungyun; Yoon, Kyunghwan; Kang, Jeongjin

2017-12-01

LGP (light guide plate) is one of the major components of LCD (liquid crystal display), and it makes surface illumination for LCD backlit. LGP is a transparent plastic plate usually produced by injection molding process. On the back of LGP there are micron size patterns for extraction of light. Recently a roll-stamping process has achieved the high mass productivity of thinner LGPs. In order to fabricate optical patterns on LGPs, a fabricating tool called as a stamper is used. Micro patterns on metallic stampers are made by several micro machining processes such as chemical etching, LIGA-reflow, and laser ablation. In this study, a roll-stamping process by using a laser ablated metallic stamper was dealt with in consideration of the compatibility with the roll-stamping process. LGP fabricating tests were performed using a roll-stamping process with four different roll pressures. Pattern shapes on the stamper fabricated by laser ablation and transcription ratios of the roll-stamping process were analyzed, and LGP luminance was evaluated. Based on the evaluation, optical simulation model for LGP was made and simulation accuracy was evaluated. Simulation results showed good agreements with optical performance of LGPs in the brightness and uniformity. It was also shown that the roll-stamped LGP has the possibility of better optical performance than the conventional injection molded LGP. It was also shown that the roll-stamped LGP with the laser ablated stamper is potential to have better optical performance than the conventional injection molded LGP.

Design fabrication and nondestructive testing of six experimental AGCarb/Intermold 3 cylinder assemblies

NASA Technical Reports Server (NTRS)

Thacher, E. F.

1972-01-01

Six subscale Intermold cylinder assemblies with a total of twelve different concepts for transition to AGCarb were fabricated. Three of the cylinder assemblies were made by helically winding the hoop fibers and three were of orthogonal configuration. The fabrication process is summarized and details of each manufacturing method are given. The objectives of the test program were to: (1) demonstrate the fabricability of the Intermold 3 subscale flanges, (2) produce an integral transition from Intermold 3 to AGCarb material, (3) define a workable manufacturing process, and (4) identify a best suited inspection method. The objectives were met and the results are described.

Design and fabrication of reflective spatial light modulator for high-dynamic-range wavefront control

NASA Astrophysics Data System (ADS)

Zhu, Hao; Bierden, Paul; Cornelissen, Steven; Bifano, Thomas; Kim, Jin-Hong

2004-10-01

This paper describes design and fabrication of a microelectromechanical metal spatial light modulator (SLM) integrated with complementary metal-oxide semiconductor (CMOS) electronics, for high-dynamic-range wavefront control. The metal SLM consists of a large array of piston-motion MEMS mirror segments (pixels) which can deflect up to 0.78 µm each. Both 32x32 and 150x150 arrays of the actuators (1024 and 22500 elements respectively) were fabricated onto the CMOS driver electronics and individual pixels were addressed. A new process has been developed to reduce the topography during the metal MEMS processing to fabricate mirror pixels with improved optical quality.

A Recipe for Soft Fluidic Elastomer Robots

PubMed Central

Marchese, Andrew D.; Katzschmann, Robert K.

2015-01-01

Abstract This work provides approaches to designing and fabricating soft fluidic elastomer robots. That is, three viable actuator morphologies composed entirely from soft silicone rubber are explored, and these morphologies are differentiated by their internal channel structure, namely, ribbed, cylindrical, and pleated. Additionally, three distinct casting-based fabrication processes are explored: lamination-based casting, retractable-pin-based casting, and lost-wax-based casting. Furthermore, two ways of fabricating a multiple DOF robot are explored: casting the complete robot as a whole and casting single degree of freedom (DOF) segments with subsequent concatenation. We experimentally validate each soft actuator morphology and fabrication process by creating multiple physical soft robot prototypes. PMID:27625913

A Recipe for Soft Fluidic Elastomer Robots.

PubMed

Marchese, Andrew D; Katzschmann, Robert K; Rus, Daniela

2015-03-01

This work provides approaches to designing and fabricating soft fluidic elastomer robots. That is, three viable actuator morphologies composed entirely from soft silicone rubber are explored, and these morphologies are differentiated by their internal channel structure, namely, ribbed, cylindrical, and pleated. Additionally, three distinct casting-based fabrication processes are explored: lamination-based casting, retractable-pin-based casting, and lost-wax-based casting. Furthermore, two ways of fabricating a multiple DOF robot are explored: casting the complete robot as a whole and casting single degree of freedom (DOF) segments with subsequent concatenation. We experimentally validate each soft actuator morphology and fabrication process by creating multiple physical soft robot prototypes.

Fabrication of a wide-field NIR integral field unit for SWIMS using ultra-precision cutting

NASA Astrophysics Data System (ADS)

Kitagawa, Yutaro; Yamagata, Yutaka; Morita, Shin-ya; Motohara, Kentaro; Ozaki, Shinobu; Takahashi, Hidenori; Konishi, Masahiro; Kato, Natsuko M.; Kobayakawa, Yutaka; Terao, Yasunori; Ohashi, Hirofumi

2016-07-01

We describe overview of fabrication methods and measurement results of test fabrications of optical surfaces for an integral field unit (IFU) for Simultaneous color Wide-field Infrared Multi-object Spectrograph, SWIMS, which is a first-generation instrument for the University of Tokyo Atacama Observatory 6.5-m telescope. SWIMS-IFU provides entire near-infrared spectrum from 0.9 to 2.5 μm simultaneously covering wider field of view of 17" × 13" compared with current near-infrared IFUs. We investigate an ultra-precision cutting technique to monolithically fabricate optical surfaces of IFU optics such as an image slicer. Using 4- or 5-axis ultra precision machine we compare the milling process and shaper cutting process to find the best way of fabrication of image slicers. The measurement results show that the surface roughness almost satisfies our requirement in both of two methods. Moreover, we also obtain ideal surface form in the shaper cutting process. This method will be adopted to other mirror arrays (i.e. pupil mirror and slit mirror, and such monolithic fabrications will also help us to considerably reduce alignment procedure of each optical elements.

Development of Impregnated Agglomerate Pelletization (IAP) process for fabrication of (Th,U)O 2 mixed oxide pellets

NASA Astrophysics Data System (ADS)

Khot, P. M.; Nehete, Y. G.; Fulzele, A. K.; Baghra, Chetan; Mishra, A. K.; Afzal, Mohd.; Panakkal, J. P.; Kamath, H. S.

2012-01-01

Impregnated Agglomerate Pelletization (IAP) technique has been developed at Advanced Fuel Fabrication Facility (AFFF), BARC, Tarapur, for manufacturing (Th, 233U)O 2 mixed oxide fuel pellets, which are remotely fabricated in hot cell or shielded glove box facilities to reduce man-rem problem associated with 232U daughter radionuclides. This technique is being investigated to fabricate the fuel for Indian Advanced Heavy Water Reactor (AHWR). In the IAP process, ThO 2 is converted to free flowing spheroids by powder extrusion route in an unshielded facility which are then coated with uranyl nitrate solution in a shielded facility. The dried coated agglomerate is finally compacted and then sintered in oxidizing/reducing atmosphere to obtain high density (Th,U)O 2 pellets. In this study, fabrication of (Th,U)O 2 mixed oxide pellets containing 3-5 wt.% UO 2 was carried out by IAP process. The pellets obtained were characterized using optical microscopy, XRD and alpha autoradiography. The results obtained were compared with the results for the pellets fabricated by other routes such as Coated Agglomerate Pelletization (CAP) and Powder Oxide Pelletization (POP) route.

Large three-dimensional photonic crystals based on monocrystalline liquid crystal blue phases.

PubMed

Chen, Chun-Wei; Hou, Chien-Tsung; Li, Cheng-Chang; Jau, Hung-Chang; Wang, Chun-Ta; Hong, Ching-Lang; Guo, Duan-Yi; Wang, Cheng-Yu; Chiang, Sheng-Ping; Bunning, Timothy J; Khoo, Iam-Choon; Lin, Tsung-Hsien

2017-09-28

Although there have been intense efforts to fabricate large three-dimensional photonic crystals in order to realize their full potential, the technologies developed so far are still beset with various material processing and cost issues. Conventional top-down fabrications are costly and time-consuming, whereas natural self-assembly and bottom-up fabrications often result in high defect density and limited dimensions. Here we report the fabrication of extraordinarily large monocrystalline photonic crystals by controlling the self-assembly processes which occur in unique phases of liquid crystals that exhibit three-dimensional photonic-crystalline properties called liquid-crystal blue phases. In particular, we have developed a gradient-temperature technique that enables three-dimensional photonic crystals to grow to lateral dimensions of ~1 cm (~30,000 of unit cells) and thickness of ~100 μm (~ 300 unit cells). These giant single crystals exhibit extraordinarily sharp photonic bandgaps with high reflectivity, long-range periodicity in all dimensions and well-defined lattice orientation.Conventional fabrication approaches for large-size three-dimensional photonic crystals are problematic. By properly controlling the self-assembly processes, the authors report the fabrication of monocrystalline blue phase liquid crystals that exhibit three-dimensional photonic-crystalline properties.

Fabrication of thorium bearing carbide fuels

DOEpatents

Gutierrez, R.L.; Herbst, R.J.; Johnson, K.W.R.

Thorium-uranium carbide and thorium-plutonium carbide fuel pellets have been fabricated by the carbothermic reduction process. Temperatures of 1750/sup 0/C and 2000/sup 0/C were used during the reduction cycle. Sintering temperatures of 1800/sup 0/C and 2000/sup 0/C were used to prepare fuel pellet densities of 87% and > 94% of theoretical, respectively. The process allows the fabrication of kilogram quantities of fuel with good reproductibility of chemical and phase composition.

Influence of wholesale lamb marketing options and merchandising styles on retail yield and fabrication time.

PubMed

Lorenzen, C L; Martin, A M; Griffin, D B; Dockerty, T R; Walter, J P; Johnson, H K; Savell, J W

1997-01-01

Lamb carcasses (n = 94) from five packing plants, selected to vary in weight class and fat thickness, were used to determine retail yield and labor requirements of wholesale lamb fabrication. Carcasses were allotted randomly according to weight class to be fabricated as whole carcasses (n = 20), three-piece boxes (n = 22), or subprimals (n = 52). Processing times (seconds) were recorded and wholesale and retail weights (kilograms) were obtained to calculate retail yield. Subprimals were fabricated into bone-in retail cuts or boneless or semi-boneless retail cuts. Retail yield for subprimal lamb legs decreased from 85.3 +/- .6% for bone-in to 68.0 +/- .7% for a completely boneless retail product. Correspondingly, processing times increased from 126.1 +/- 5.4 s to 542.0 +/- 19.2 s for bone-in and boneless legs, respectively. For all subprimals, retail yield percentage tended to decrease and total processing time increase as cuts were fabricated to boneless or semi-boneless end points compared with a bone-in end point. Percentage retail yield did not differ (P > .05) among whole carcass, three-piece box, and subprimal marketing methods. Total processing time was shorter for subprimals (P < .05) than for the other two marketing methods.

Rapid ILs-polishing Processes Toward Flexible Nanostructured Paper with Dually High Transparency and Haze.

PubMed

Ou, Yanghao; Chen, Jinbo; Lu, Pengbo; Cheng, Fan; Lin, Meiyan; Su, Lingfeng; Li, Jun; Liu, Detao

2017-07-31

Biodegradable highly nanostructured paper has received great interest in past years due to its excellent optical properties which facilitate its wide applications in green flexible electronics and devices. However, energy and/or time-consuming procedure during the process of fabricating most nanostructured transparent paper are presently the main obstacle to their scalable production. In this work, we demonstrated a novel nanostructured paper with dually high transparency (∼91%) and high haze (∼89%) that was directly fabricated from original paper with rapid ILs-polishing processes. The whole fabricating time only requires 10 min. Compared to the previously reported nanopaper made of the isolated cellulose nanofibers by pure mechanical and/or chemical approaches, this work presented herein is devoted to use green ILs to polish directly the micrometer-sized fibrous paper into the nanostructured paper. This new method brings a rapid fabrication of transparent nanostructured paper while also retaining dual intriguing properties both in optical transmittance and haze. This work is capable of fabricating next-generation flexible and highly transparent and haze paper by a high-speed roll-to-roll manufacturing process with a much lower cost.

Heater Validation for the NEXT-C Hollow Cathodes

NASA Technical Reports Server (NTRS)

Verhey, Timothy R.; Soulas, George C.; Mackey, Jonathan Ar.

2017-01-01

Swaged cathode heaters whose design was successfully demonstrated under a prior flight project are to be provided by the NASA Glenn Research Center for the NEXT-C ion thruster being fabricated by Aerojet Rocketdyne. Extensive requalification activities were performed to validate process controls that had to be re-established or revised because systemic changes prevented reuse of the past approaches. A development batch of heaters was successfully fabricated based on the new process controls. Acceptance and cyclic life testing of multiple discharge and neutralizer sized heaters extracted from the development batch was initiated in August, 2016, with the last heater completing testing in April, 2017. Cyclic life testing results substantially exceeded the NEXT-C thruster requirement as well as all past experience for GRC fabricated units. The heaters demonstrated ultimate cyclic life capability of 19050 to 33500 cycles. A qualification batch of heaters is now being fabricated using the finalized process controls. A set of six heaters will be acceptance and cyclic tested to verify conformance to the behavior observed with the development heaters. The heaters for flight use will be then be provided to the contractor. This paper summarizes the fabrication process control activities and the acceptance and life testing of the development heater units.

Bonded polyimide fuel cell package and method thereof

DOEpatents

Morse, Jeffrey D.; Jankowski, Alan; Graff, Robert T.; Bettencourt, Kerry

2005-11-01

Described herein are processes for fabricating microfluidic fuel cell systems with embedded components in which micron-scale features are formed by bonding layers of DuPont Kapton.TM. polyimide laminate. A microfluidic fuel cell system fabricated using this process is also described.

19 CFR 10.222 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-04-01

... together of all components (including thread, decorative embellishments, buttons, zippers, or similar...,” when used with reference to yarns, means that all of the production processes, starting with the... country, and, when used with reference to fabric(s), means that all of the production processes, starting...

19 CFR 10.222 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-04-01

... together of all components (including thread, decorative embellishments, buttons, zippers, or similar...,” when used with reference to yarns, means that all of the production processes, starting with the... country, and, when used with reference to fabric(s), means that all of the production processes, starting...

19 CFR 10.222 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-04-01

... together of all components (including thread, decorative embellishments, buttons, zippers, or similar...,” when used with reference to yarns, means that all of the production processes, starting with the... country, and, when used with reference to fabric(s), means that all of the production processes, starting...

Method of preparation of bonded polyimide fuel cell package

DOEpatents

Morse, Jeffrey D [Martinez, CA; Jankowski, Alan [Livermore, CA; Graff, Robert T [Modesto, CA; Bettencourt, Kerry [Dublin, CA

2011-04-26

Described herein are processes for fabricating microfluidic fuel cell systems with embedded components in which micron-scale features are formed by bonding layers of DuPont Kapton.TM. polyimide laminate. A microfluidic fuel cell system fabricated using this process is also described.

Scale-up of an ultrasound-enhanced bioscouring process

USDA-ARS?s Scientific Manuscript database

Using previously determined optimized reaction conditions, an ultrasound-enhanced bioscouring process was scaled to ten gallon capacity and a system of rollers was added which allowed for continuous fabric feed and equipment operation. UV-Vis photospectroscopic data from bioscoured fabric samples co...

Continuous Fiber Ceramic Composite (CFCC) Program: Gaseous Nitridation

DOE Office of Scientific and Technical Information (OSTI.GOV)

R. Suplinskas G. DiBona; W. Grant

2001-10-29

Textron has developed a mature process for the fabrication of continuous fiber ceramic composite (CFCC) tubes for application in the aluminum processing and casting industry. The major milestones in this project are System Composition; Matrix Formulation; Preform Fabrication; Nitridation; Material Characterization; Component Evaluation

The layered evolution of fabric and microstructure of snow at Point Barnola, Central East Antarctica

NASA Astrophysics Data System (ADS)

Calonne, Neige; Montagnat, Maurine; Matzl, Margret; Schneebeli, Martin

2017-02-01

Snow fabric, defined as the distribution of the c-axis orientations of the ice crystals in snow, is poorly known. So far, only one study exits that measured snow fabric based on a statistically representative technique. This recent study has revealed the impact of temperature gradient metamorphism on the evolution of fabric in natural snow, based on cold laboratory experiments. On polar ice sheets, snow properties are currently investigated regarding their strong variability in time and space, notably because of their potential influence on firn processes and consequently on ice core analysis. Here, we present measurements of fabric and microstructure of snow from Point Barnola, East Antarctica (close to Dome C). We analyzed a snow profile from 0 to 3 m depth, where temperature gradients occur. The main contributions of the paper are (1) a detailed characterization of snow in the upper meters of the ice sheet, especially by providing data on snow fabric, and (2) the study of a fundamental snow process, never observed up to now in a natural snowpack, namely the role of temperature gradient metamorphism on the evolution of the snow fabric. Snow samples were scanned by micro-tomography to measure continuous profiles of microstructural properties (density, specific surface area and pore thickness). Fabric analysis was performed using an automatic ice texture analyzer on 77 representative thin sections cut out from the samples. Different types of snow fabric could be identified and persist at depth. Snow fabric is significantly correlated with snow microstructure, pointing to the simultaneous influence of temperature gradient metamorphism on both properties. We propose a mechanism based on preferential grain growth to explain the fabric evolution under temperature gradients. Our work opens the question of how such a layered profile of fabric and microstructure evolves at depth and further influences the physical and mechanical properties of snow and firn. More generally, it opens the way to further studies on the influence of the snow fabric in snow processes related to anisotropic properties of ice such as grain growth, mechanical response, electromagnetic behavior.

Resin/graphite fiber composites

NASA Technical Reports Server (NTRS)

Cavano, P. J.

1974-01-01

Processing techniques were developed for the fabrication of both polyphenylquinoxaline and polyimide composites by the in situ polymerization of monomeric reactants directly on the graphite reinforcing fibers, rather than using previously prepared prepolymer varnishes. Void-free polyphenylquinoxaline composites were fabricated and evaluated for room and elevated flexure and shear properties. The technology of the polyimide system was advanced to the point where the material is ready for commercial exploitation. A reproducible processing cycle free of operator judgment factors was developed for fabrication of void-free composites exhibiting excellent mechanical properties and a long time isothermal life in the range of 288 C to 316 C. The effects of monomer reactant stoichiometry and process modification on resin flow were investigated. Demonstration of the utility and quality of this polyimide system was provided through the successful fabrication and evaluation of four complex high tip speed fan blades.

Fabricating micro-instruments in surface-micromachined polycrystalline silicon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Comtois, J.H.; Michalicek, M.A.; Barron, C.C.

1997-04-01

Smaller, lighter instruments can be fabricated as Micro-Electro-Mechanical Systems (MEMS), having micron scale moving parts packaged together with associated control and measurement electronics. Batch fabrication of these devices will make economical applications such as condition-based machine maintenance and remote sensing. The choice of instrumentation is limited only by the designer`s imagination. This paper presents one genre of MEMS fabrication, surface-micromachined polycrystalline silicon (polysilicon). Two currently available but slightly different polysilicon processes are presented. One is the ARPA-sponsored ``Multi-User MEMS ProcesS`` (MUMPS), available commercially through MCNC; the other is the Sandia National Laboratories ``Sandia Ultra-planar Multilevel MEMS Technology`` (SUMMiT). Example componentsmore » created in both processes will be presented, with an emphasis on actuators, actuator force testing instruments, and incorporating actuators into larger instruments.« less

Study of scratch drive actuator force characteristics

NASA Astrophysics Data System (ADS)

Li, Lijie; Brown, J. Gordon; Uttamchandani, Deepak

2002-11-01

Microactuators are one of the key components in MEMS technology, and various designs have been realized through different fabrication processes. One type of microactuator commonly used is the scratch drive actuator (SDA) that is frequently fabricated by surface micromachining processes. An experimental investigation has been conducted on the force characteristics of SDAs fabricated using the JDSU Microsystems MUMPs process. One-, two-, three- and four-plate SDAs connected to box-springs have been designed and fabricated for these experiments using MUMPs run 44. The spring constant for the box-springs has been calculated by FEM using ANSYS software. The product of the spring constant and spring extension is used to measure the forces produced by these SDAs. It is estimated that the forces produced exceed 250 μN from a one-plate SDA and 850 μN from a four-plate SDA.

VPS GRCop-84 Liner Development Efforts

NASA Technical Reports Server (NTRS)

Elam, Sandra K.; Holmes, Richard; McKechnie, Tim; Hickman, Robert; Pickens, Tim

2003-01-01

For the past several years, NASA's Marshall Space Flight Center (MSFC) has been working with Plasma Processes, Inc. (PPI) to fabricate combustion chamber liners using the Vacuum Plasma Spray (VPS) process. Multiple liners of a variety of shapes and sizes have been created. Each liner has been fabricated with GRCop-84 (a copper alloy with chromium and niobium) and a functional gradient coating (FGC) on the hot wall. While the VPS process offers versatility and a reduced fabrication schedule, the material system created with VPS allows the liners to operate at higher temperatures, with maximum blanch resistance and improved cycle life. A subscal unit (5K lbf thrust class) is being cycle tested in a LOX/Hydrogen thrust chamber assembly at MSFC. To date, over 75 hot-fire tests have been accumulated on this article. Tests include conditions normally detrimental to conventional materials, yet the VPS GRCop-84 liner has yet to show any signs of degradation. A larger chamber (15K lbf thrust class) has also been fabricated and is being prepared for hot-fire testing at MSFC near the end of 2003. Linear liners have been successfully created to further demonstrate the versatility of the process. Finally, scale up issues for the VPS process are being tackled with efforts to fabricate a full size, engine class liner. Specifically, a liner for the SSME's Main Combustion Chamber (MCC) has recently been attempted. The SSME size was chosen for convenience, since its design was readily available and its size was sufficient to tackle specific issues. Efforts to fabricate these large liners have already provided valuable lessons for using this process for engine programs. The material quality for these large units is being evaluated with destructive analysis and these results will be available by the end of 2003.

Strong Influence of Humidity on Low-Temperature Thin-Film Fabrication via Metal Aqua Complex for High Performance Oxide Semiconductor Thin-Film Transistors.

PubMed

Lim, Keon-Hee; Huh, Jae-Eun; Lee, Jinwon; Cho, Nam-Kwang; Park, Jun-Woo; Nam, Bu-Il; Lee, Eungkyu; Kim, Youn Sang

2017-01-11

Oxide semiconductors thin film transistors (OS TFTs) with good transparency and electrical performance have great potential for future display technology. In particular, solution-processed OS TFTs have been attracted much attention due to many advantages such as continuous, large scale, and low cost processability. Recently, OS TFTs fabricated with a metal aqua complex have been focused because they have low temperature processability for deposition on flexible substrate as well as high field-effect mobility for application of advanced display. However, despite some remarkable results, important factors to optimize their electrical performance with reproducibility and uniformity have not yet been achieved. Here, we newly introduce the strong effects of humidity to enhance the electrical performance of OS TFTs fabricated with the metal aqua complex. Through humidity control during the spin-coating process and annealing process, we successfully demonstrate solution-processed InO x /SiO 2 TFTs with a good electrical uniformity of ∼5% standard deviation, showing high average field-effect mobility of 2.76 cm 2 V -1 s -1 and 15.28 cm 2 V -1 s -1 fabricated at 200 and 250 °C, respectively. Also, on the basis of the systematic analyses, we demonstrate the mechanism for the change in electrical properties of InO x TFTs depending on the humidity control. Finally, on the basis of the mechanism, we extended the humidity control to the fabrication of the AlO x insulator. Subsequently, we successfully achieved humidity-controlled InO x /AlO x TFTs fabricated at 200 °C showing high average field-effect mobility of 9.5 cm 2 V -1 s -1 .

Lateral solid phase epitaxy of silicon and application to the fabrication of metal oxide semiconductor field-effect transistors

NASA Astrophysics Data System (ADS)

Greene, Brian Joseph

Thin film silicon on insulator fabrication is an increasingly important technology requirement for improving performance in future generation devices and circuits. One process for SOI fabrication that has recently been generating renewed interest is Lateral Solid Phase Epitaxy (LSPE) of silicon over oxide. This process involves annealing amorphous silicon that has been deposited on oxide patterned Si wafers. The (001) Si substrate forms the crystalline seed for epitaxial growth, permitting the generation of Si films that are both single crystal, and oriented to the substrate. This method is particularly attractive to fabrication that requires low temperature processing, because the Si films are deposited in the amorphous phase at temperatures near 525°C, and crystallized at temperatures near 570°C. It is also attractive for applications requiring three dimensional stacking of active silicon device layers, due to the relatively low temperatures involved. For sub-50 nm gate length MOSFET fabrication, an SOI thickness on the order of 10 nm will be required. One limitation of the LSPE process has been the need for thick films (0.5--2 mum) and/or heavy P doping (10 19--1020 cm-3) to increase the maximum achievable lateral growth distance, and therefore minimize the area on the substrate occupied by seed holes. This dissertation discusses the characterization and optimization of process conditions for large area LSPE silicon film growth, as well as efforts to adapt the traditional LSPE process to achieve ultra-thin SOI layers (Tsilicon ≤ 25 nm) while avoiding the use of heavy active doping layers. MOSFETs fabricated in these films that exhibit electron mobility comparable to the Universal Si MOS Mobility are described.

Process Development of Gallium Nitride Phosphide Core-Shell Nanowire Array Solar Cell

NASA Astrophysics Data System (ADS)

Chuang, Chen

Dilute Nitride GaNP is a promising materials for opto-electronic applications due to its band gap tunability. The efficiency of GaNxP1-x /GaNyP1-y core-shell nanowire solar cell (NWSC) is expected to reach as high as 44% by 1% N and 9% N in the core and shell, respectively. By developing such high efficiency NWSCs on silicon substrate, a further reduction of the cost of solar photovoltaic can be further reduced to 61$/MWh, which is competitive to levelized cost of electricity (LCOE) of fossil fuels. Therefore, a suitable NWSC structure and fabrication process need to be developed to achieve this promising NWSC. This thesis is devoted to the study on the development of fabrication process of GaNxP 1-x/GaNyP1-y core-shell Nanowire solar cell. The thesis is divided into two major parts. In the first parts, previously grown GaP/GaNyP1-y core-shell nanowire samples are used to develop the fabrication process of Gallium Nitride Phosphide nanowire solar cell. The design for nanowire arrays, passivation layer, polymeric filler spacer, transparent col- lecting layer and metal contact are discussed and fabricated. The property of these NWSCs are also characterized to point out the future development of Gal- lium Nitride Phosphide NWSC. In the second part, a nano-hole template made by nanosphere lithography is studied for selective area growth of nanowires to improve the structure of core-shell NWSC. The fabrication process of nano-hole templates and the results are presented. To have a consistent features of nano-hole tem- plate, the Taguchi Method is used to optimize the fabrication process of nano-hole templates.

New integrated silicon-PDMS process for compliant micro-mechanisms

NASA Astrophysics Data System (ADS)

Haouas, Wissem; Dahmouche, Redwan; Agnus, Joël; Le Fort-Piat, Nadine; Laurent, Guillaume J.

2017-12-01

Polydimethylsiloxane (PDMS) elastomers are used for many applications, such as microfluidics and micro-engineering. This paper presents a new process of integrating soft elastomers into a silicon structure without any assembly steps. The novelty of this process is the use of only one deep reactive ion etch (DRIE) instead of two or more as developed in previous works. Thus, this fabrication process allows the use of elastomers that are usually not compatible with some fabrication processes. Compliant flexures with different interference shapes have been designed, simulated, fabricated, and characterized for generic use and notably for micro-robot joints and compliant micro-systems. The experimental results show that the 400 μm  ×  400 μm cross-sectional area samples can be bended more than 60\\circ without delamination.

Performance improvement for solution-processed high-mobility ZnO thin-film transistors

NASA Astrophysics Data System (ADS)

Sha Li, Chen; Li, Yu Ning; Wu, Yi Liang; Ong, Beng S.; Loutfy, Rafik O.

2008-06-01

The fabrication technology of stable, non-toxic, transparent, high performance zinc oxide (ZnO) thin-film semiconductors via the solution process was investigated. Two methods, which were, respectively, annealing a spin-coated precursor solution and annealing a drop-coated precursor solution, were compared. The prepared ZnO thin-film semiconductor transistors have well-controlled, preferential crystal orientation and exhibit superior field-effect performance characteristics. But the ZnO thin-film transistor (TFT) fabricated by annealing a drop-coated precursor solution has a distinctly elevated linear mobility, which further approaches the saturated mobility, compared with that fabricated by annealing a spin-coated precursor solution. The performance of the solution-processed ZnO TFT was further improved when substituting the spin-coating process by the drop-coating process.

Fabrication of three-dimensional hybrid nanostructure-embedded ITO and its application as a transparent electrode for high-efficiency solution processable organic photovoltaic devices.

PubMed

Kim, Jeong Won; Jeon, Hwan-Jin; Lee, Chang-Lyoul; Ahn, Chi Won

2017-03-02

Well-aligned, high-resolution (10 nm), three-dimensional (3D) hybrid nanostructures consisting of patterned cylinders and Au islands were fabricated on ITO substrates using an ion bombardment process and a tilted deposition process. The fabricated 3D hybrid nanostructure-embedded ITO maintained its excellent electrical and optical properties after applying a surface-structuring process. The solution processable organic photovoltaic device (SP-OPV) employing a 3D hybrid nanostructure-embedded ITO as the anode displayed a 10% enhancement in the photovoltaic performance compared to the photovoltaic device prepared using a flat ITO electrode, due to the improved charge collection (extraction and transport) efficiency as well as light absorbance by the photo-active layer.

Angle-Ply Weaving

NASA Technical Reports Server (NTRS)

Farley, Gary L.

1990-01-01

Bias-direction or angle-ply weaving is proposed new process for weaving fibers along bias in conventional planar fabric or in complicated three-dimensional multilayer fabric preform of fiber-reinforced composite structure. Based upon movement of racks of needles and corresponding angle yarns across fabric as fabric being formed. Fibers woven along bias increases shear stiffness and shear strength of preform, increasing value of preform as structural member.

Development and Optimization of Silver Nanoparticle Formulation for Fabrication

DTIC Science & Technology

2015-08-14

Development and Optimization of Silver Nanoparticle Formulation for Fabrication Publication Type: DJournal/ Paper D Book Chapter ~ Tech Report D...leofPublicationorPresentation: Deve l opment and Optimization of Silver Nanoparticle Formulation for Fabrication 3. Author(s): (List authors starting...fabrication process of silver nanoparticl es could improve future silver containing products , which is i mpor tant to l owering toxicity and improving

Using atmospheric pressure plasma treatment for treating grey cotton fabric.

PubMed

Kan, Chi-Wai; Lam, Chui-Fung; Chan, Chee-Kooi; Ng, Sun-Pui

2014-02-15

Conventional wet treatment, desizing, scouring and bleaching, for grey cotton fabric involves the use of high water, chemical and energy consumption which may not be considered as a clean process. This study aims to investigate the efficiency of the atmospheric pressure plasma (APP) treatment on treating grey cotton fabric when compared with the conventional wet treatment. Grey cotton fabrics were treated with different combinations of plasma parameters with helium and oxygen gases and also through conventional desizing, scouring and bleaching processes in order to obtain comparable results. The results obtained from wicking and water drop tests showed that wettability of grey cotton fabrics was greatly improved after plasma treatment and yielded better results than conventional desizing and scouring. The weight reduction of plasma treated grey cotton fabrics revealed that plasma treatment can help remove sizing materials and impurities. Chemical and morphological changes in plasma treated samples were analysed by FTIR and SEM, respectively. Finally, dyeability of the plasma treated and conventional wet treated grey cotton fabrics was compared and the results showed that similar dyeing results were obtained. This can prove that plasma treatment would be another choice for treating grey cotton fabrics. Copyright © 2013 Elsevier Ltd. All rights reserved.

CAD/CAM machining Vs pre-sintering in-lab fabrication techniques of Y-TZP ceramic specimens: Effects on their mechanical fatigue behavior.

PubMed

Zucuni, C P; Guilardi, L F; Fraga, S; May, L G; Pereira, G K R; Valandro, L F

2017-07-01

This study evaluated the effects of different pre-sintering fabrication processing techniques of Y-TZP ceramic (CAD/CAM Vs. in-lab), considering surface characteristics and mechanical performance outcomes. Pre-sintered discs of Y-TZP ceramic (IPS e.max ZirCAD, Ivoclar Vivadent) were produced using different pre-sintering fabrication processing techniques: Machined- milling with a CAD/CAM system; Polished- fabrication using a cutting device followed by polishing (600 and 1200 SiC papers); Xfine- fabrication using a cutting machine followed by grinding with extra-fine diamond bur (grit size 30 μm); Fine- fabrication using a cutting machine followed by grinding with fine diamond bur (grit size 46 μm); SiC- fabrication using a cutting machine followed by grinding with 220 SiC paper. Afterwards, the discs were sintered and submitted to roughness (n=35), surface topography (n=2), phase transformation (n=2), biaxial flexural strength (n=20), and biaxial flexural fatigue strength (fatigue limit) (n=15) analyses. No monoclinic-phase content was observed in all processing techniques. It can be observed that obtaining a surface with similar characteristics to CAD/CAM milling is essential for the observation of similar mechanical performance. On this sense, grinding with fine diamond bur before sintering (Fine group) was the best mimic protocol in comparison to the CAD/CAM milling. Copyright © 2017 Elsevier Ltd. All rights reserved.

Strategy for Texture Management in Metals Additive Manufacturing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirka, Michael M.; Lee, Yousub; Greeley, Duncan A.

Additive manufacturing (AM) technologies have long been recognized for their ability to fabricate complex geometric components directly from models conceptualized through computers, allowing for complicated designs and assemblies to be fabricated at lower costs, with shorter time to market, and improved function. Lacking behind the design complexity aspect is the ability to fully exploit AM processes for control over texture within AM components. Currently, standard heat-fill strategies utilized in AM processes result in largely columnar grain structures. Here, we propose a point heat source fill for the electron beam melting (EBM) process through which the texture in AM materials canmore » be controlled. Using this point heat source strategy, the ability to form either columnar or equiaxed grain structures upon solidification through changes in the process parameters associated with the point heat source fill is demonstrated for the nickel-base superalloy, Inconel 718. Mechanically, the material is demonstrated to exhibit either anisotropic properties for the columnar-grained material fabricated through using the standard raster scan of the EBM process or isotropic properties for the equiaxed material fabricated using the point heat source fill.« less

Strategy for Texture Management in Metals Additive Manufacturing

DOE PAGES

Kirka, Michael M.; Lee, Yousub; Greeley, Duncan A.; ...

2017-01-31

Additive manufacturing (AM) technologies have long been recognized for their ability to fabricate complex geometric components directly from models conceptualized through computers, allowing for complicated designs and assemblies to be fabricated at lower costs, with shorter time to market, and improved function. Lacking behind the design complexity aspect is the ability to fully exploit AM processes for control over texture within AM components. Currently, standard heat-fill strategies utilized in AM processes result in largely columnar grain structures. Here, we propose a point heat source fill for the electron beam melting (EBM) process through which the texture in AM materials canmore » be controlled. Using this point heat source strategy, the ability to form either columnar or equiaxed grain structures upon solidification through changes in the process parameters associated with the point heat source fill is demonstrated for the nickel-base superalloy, Inconel 718. Mechanically, the material is demonstrated to exhibit either anisotropic properties for the columnar-grained material fabricated through using the standard raster scan of the EBM process or isotropic properties for the equiaxed material fabricated using the point heat source fill.« less

USHPRR FUEL FABRICATION PILLAR: FABRICATION STATUS, PROCESS OPTIMIZATIONS, AND FUTURE PLANS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wight, Jared M.; Joshi, Vineet V.; Lavender, Curt A.

The Fuel Fabrication (FF) Pillar, a project within the U.S. High Performance Research Reactor Conversion program of the National Nuclear Security Administration’s Office of Material Management and Minimization, is tasked with the scale-up and commercialization of high-density monolithic U-Mo fuel for the conversion of appropriate research reactors to use of low-enriched fuel. The FF Pillar has made significant steps to demonstrate and optimize the baseline co-rolling process using commercial-scale equipment at both the Y-12 National Security Complex (Y-12) and BWX Technologies (BWXT). These demonstrations include the fabrication of the next irradiation experiment, Mini-Plate 1 (MP-1), and casting optimizations at Y-12.more » The FF Pillar uses a detailed process flow diagram to identify potential gaps in processing knowledge or demonstration, which helps direct the strategic research agenda of the FF Pillar. This paper describes the significant progress made toward understanding the fuel characteristics, and models developed to make informed decisions, increase process yield, and decrease lifecycle waste and costs.« less

Inkjet-Printed Graphene/PEDOT:PSS Temperature Sensors on a Skin-Conformable Polyurethane Substrate.

PubMed

Vuorinen, Tiina; Niittynen, Juha; Kankkunen, Timo; Kraft, Thomas M; Mäntysalo, Matti

2016-10-18

Epidermal electronic systems (EESs) are skin-like electronic systems, which can be used to measure several physiological parameters from the skin. This paper presents materials and a simple, straightforward fabrication process for skin-conformable inkjet-printed temperature sensors. Epidermal temperature sensors are already presented in some studies, but they are mainly fabricated using traditional photolithography processes. These traditional fabrication routes have several processing steps and they create a substantial amount of material waste. Hence utilizing printing processes, the EES may become attractive for disposable systems by decreasing the manufacturing costs and reducing the wasted materials. In this study, the sensors are fabricated with inkjet-printed graphene/PEDOT:PSS ink and the printing is done on top of a skin-conformable polyurethane plaster (adhesive bandage). Sensor characterization was conducted both in inert and ambient atmosphere and the graphene/PEDOT:PSS temperature sensors (thermistors) were able reach higher than 0.06% per degree Celsius sensitivity in an optimal environment exhibiting negative temperature dependence.

Development of wet process with substitution reaction for the mass production of Li 2TiO 3 pebbles

NASA Astrophysics Data System (ADS)

Tsuchiya, Kunihiko; Kawamura, Hiroshi

2000-12-01

Recently, lithium titanate (Li 2TiO 3) has attracted the attention of many researchers from the point of good tritium recovery at low temperature, chemical stability, etc. As the shape of Li 2TiO 3, a small pebble was selected as the Japanese design for a fusion reactor blanket. On the other hand, as the fabrication method of Li 2TiO 3 pebbles, the wet process is the most advantageous from the viewpoint of mass production, etc. In this study, fabrication of small Li 2TiO 3 pebbles less than ∅0.5 mm was performed by the wet process with substitution reaction, and the characteristics of Li 2TiO 3 pebbles fabricated by this process were evaluated. From the results of the fabrication tests, excellent prospects were obtained concerning mass production of Li 2TiO 3 pebbles with the target density (80-85% T.D.) and target diameter (less than ∅0.5 mm).

Fabrication of high quality aspheric microlens array by dose-modulated lithography and surface thermal reflow

NASA Astrophysics Data System (ADS)

Huang, Shengzhou; Li, Mujun; Shen, Lianguan; Qiu, Jinfeng; Zhou, Youquan

2018-03-01

A novel fabrication method for high quality aspheric microlens array (MLA) was developed by combining the dose-modulated DMD-based lithography and surface thermal reflow process. In this method, the complex shape of aspheric microlens is pre-modeled via dose modulation in a digital micromirror device (DMD) based maskless projection lithography. And the dose modulation mainly depends on the distribution of exposure dose of photoresist. Then the pre-shaped aspheric microlens is polished by a following non-contact thermal reflow (NCTR) process. Different from the normal process, the reflow process here is investigated to improve the surface quality while keeping the pre-modeled shape unchanged, and thus will avoid the difficulties in generating the aspheric surface during reflow. Fabrication of a designed aspheric MLA with this method was demonstrated in experiments. Results showed that the obtained aspheric MLA was good in both shape accuracy and surface quality. The presented method may be a promising approach in rapidly fabricating high quality aspheric microlens with complex surface.

A hybrid life cycle inventory of nano-scale semiconductor manufacturing.

PubMed

Krishnan, Nikhil; Boyd, Sarah; Somani, Ajay; Raoux, Sebastien; Clark, Daniel; Dornfeld, David

2008-04-15

The manufacturing of modern semiconductor devices involves a complex set of nanoscale fabrication processes that are energy and resource intensive, and generate significant waste. It is important to understand and reduce the environmental impacts of semiconductor manufacturing because these devices are ubiquitous components in electronics. Furthermore, the fabrication processes used in the semiconductor industry are finding increasing application in other products, such as microelectromechanical systems (MEMS), flat panel displays, and photovoltaics. In this work we develop a library of typical gate-to-gate materials and energy requirements, as well as emissions associated with a complete set of fabrication process models used in manufacturing a modern microprocessor. In addition, we evaluate upstream energy requirements associated with chemicals and materials using both existing process life cycle assessment (LCA) databases and an economic input-output (EIO) model. The result is a comprehensive data set and methodology that may be used to estimate and improve the environmental performance of a broad range of electronics and other emerging applications that involve nano and micro fabrication.

Key Processes of Silicon-On-Glass MEMS Fabrication Technology for Gyroscope Application.

PubMed

Ma, Zhibo; Wang, Yinan; Shen, Qiang; Zhang, Han; Guo, Xuetao

2018-04-17

MEMS fabrication that is based on the silicon-on-glass (SOG) process requires many steps, including patterning, anodic bonding, deep reactive ion etching (DRIE), and chemical mechanical polishing (CMP). The effects of the process parameters of CMP and DRIE are investigated in this study. The process parameters of CMP, such as abrasive size, load pressure, and pH value of SF1 solution are examined to optimize the total thickness variation in the structure and the surface quality. The ratio of etching and passivation cycle time and the process pressure are also adjusted to achieve satisfactory performance during DRIE. The process is optimized to avoid neither the notching nor lag effects on the fabricated silicon structures. For demonstrating the capability of the modified CMP and DRIE processes, a z-axis micro gyroscope is fabricated that is based on the SOG process. Initial test results show that the average surface roughness of silicon is below 1.13 nm and the thickness of the silicon is measured to be 50 μm. All of the structures are well defined without the footing effect by the use of the modified DRIE process. The initial performance test results of the resonant frequency for the drive and sense modes are 4.048 and 4.076 kHz, respectively. The demands for this kind of SOG MEMS device can be fulfilled using the optimized process.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirka, Michael M.; Nandwana, Peeyush; Lee, Yousub

Additive manufacturing (AM) of metals is rapidly emerging as an established manufacturing process for metal components. Unlike traditional metals fabrication processes, metals fabricated via AM undergo localized thermal cycles during fabrication. As a result, AM presents the opportunity to control the liquid-solid phase transformation, i.e. material texture. But, thermal cycling presents challenges from the standpoint of solid-solid phase transformations. We will discuss the opportunities and challenges in metals AM in the context of texture control and associated solid-solid phase transformations in Ti-6Al-4V and Inconel 718.

Fabrication of polydimethylsiloxane (PDMS) - based multielectrode array for neural interface.

PubMed

Kim, Jun-Min; Oh, Da-Rong; Sanchez, Joaquin; Kim, Shang-Hyub; Seo, Jong-Mo

2013-01-01

Flexible multielectrode arrays (MEAs) are being developed with various materials, and polyimide has been widely used due to the conveniece of process. Polyimide is developed in the form of photoresist. And this enable precise and reproducible fabrication. PDMS is another good candidate for MEA base material, but it has poor surface energy and etching property. In this paper, we proposed a better fabrication process that could modify PDMS surface for a long time and open the site of electrode and pad efficiently without PDMS etching.

Optimised process for fabricating tapered long period gratings

NASA Astrophysics Data System (ADS)

Mullaney, K.; Staines, S. E.; James, S. W.; Tatam, R. P.

2017-04-01

The process of fabricating tapered long period gratings (TLPGs) using a CO2 laser is described. TLPGs with a period spacing of 378 μm, were fabricated by optimization of the taper waist diameter and careful control of the duty-cycle and its uniformity along the length of the grating. The 6-period TLPGs exhibited a pass-band insertion loss of 0.6 dB, resonance band extinction values of 3 dB and had a physical length of 2.27 mm.

Mechanically detected terahertz electron spin resonance using SOI-based thin piezoresistive microcantilevers

NASA Astrophysics Data System (ADS)

Ohmichi, Eiji; Miki, Toshihiro; Horie, Hidekazu; Okamoto, Tsubasa; Takahashi, Hideyuki; Higashi, Yoshinori; Itoh, Shoichi; Ohta, Hitoshi

2018-02-01

We developed piezoresistive microcantilevers for mechanically detected electron spin resonance (ESR) in the millimeter-wave region. In this article, fabrication process and device characterization of our self-sensing microcantilevers are presented. High-frequency ESR measurements of a microcrystal of paramagnetic sample is also demonstrated at multiple frequencies up to 160 GHz at liquid helium temperature. Our fabrication is based on relatively simplified processes with silicon-on-insulator (SOI) wafers and spin-on diffusion doping, thus enabling cost-effective and time-saving cantilever fabrication.

PMR polyimides: Processable high temperature composite matrix resins

NASA Technical Reports Server (NTRS)

Winters, W. E.; Serafini, T. T.

1975-01-01

Processing reproducibility and versatility were demonstrated for producing addition-cured polyimide/graphite fiber composites using an in situ polymerization of monomeric reactants directly on the fiber surface. The polymers so derived, designated PMR polyimides, can be fabricated into composite structures by laminating, random fiber molding or autoclave curing. Composites were determined to be thermally stable and retain useful properties after extended exposures at 550 F to 650 F. The material and fabrication capability were demonstrated by the fabrication and evaluation of prototype complex fan blades.

PMR polyimides - Processable high temperature composite matrix resins

NASA Technical Reports Server (NTRS)

Winters, W. E.; Serafini, T. T.

1975-01-01

Processing reproducibility and versatility were demonstrated for producing addition-cured polyimide/graphite fiber composites using a unique in situ polymerization of monomeric reactants directly on the fiber surface. The polymers so derived, designated PMR polyimides, can be fabricated into composite structures by laminating, random fiber molding or autoclave curing. Composites were determined to be thermally stable and retain useful properties after extended exposures at 550 to 650 F. The material and fabrication capability were demonstrated by the fabrication and evaluation of prototype complex fan blades.-

Compact Layers of Hybrid Halide Perovskites Fabricated via the Aerosol Deposition Process-Uncoupling Material Synthesis and Layer Formation.

PubMed

Panzer, Fabian; Hanft, Dominik; Gujar, Tanaji P; Kahle, Frank-Julian; Thelakkat, Mukundan; Köhler, Anna; Moos, Ralf

2016-04-08

We present the successful fabrication of CH₃NH₃PbI₃ perovskite layers by the aerosol deposition method (ADM). The layers show high structural purity and compactness, thus making them suitable for application in perovskite-based optoelectronic devices. By using the aerosol deposition method we are able to decouple material synthesis from layer processing. Our results therefore allow for enhanced and easy control over the fabrication of perovskite-based devices, further paving the way for their commercialization.

Novel Applications of Rapid Prototyping in Gamma-ray and X-ray Imaging

PubMed Central

Miller, Brian W.; Moore, Jared W.; Gehm, Michael E.; Furenlid, Lars R.; Barrett, Harrison H.

2010-01-01

Advances in 3D rapid-prototyping printers, 3D modeling software, and casting techniques allow for the fabrication of cost-effective, custom components in gamma-ray and x-ray imaging systems. Applications extend to new fabrication methods for custom collimators, pinholes, calibration and resolution phantoms, mounting and shielding components, and imaging apertures. Details of the fabrication process for these components are presented, specifically the 3D printing process, cold casting with a tungsten epoxy, and lost-wax casting in platinum. PMID:22984341

Metal matrix composite fabrication processes for high performance aerospace structures

NASA Astrophysics Data System (ADS)

Ponzi, C.

A survey is conducted of extant methods of metal matrix composite (MMC) production in order to serve as a basis for prospective MMC users' selection of a matrix/reinforcement combination, cost-effective primary fabrication methods, and secondary fabrication techniques for the achievement of desired performance levels. Attention is given to the illustrative cases of structural fittings, control-surface connecting rods, hypersonic aircraft air inlet ramps, helicopter swash plates, and turbine rotor disks. Methods for technical and cost analysis modeling useful in process optimization are noted.

Fabrication of lightweight ceramic mirrors by means of a chemical vapor deposition process

NASA Technical Reports Server (NTRS)

Goela, Jitendra S. (Inventor); Taylor, Raymond L. (Inventor)

1991-01-01

A process to fabricate lightweigth ceramic mirrors, and in particular, silicon/silicon carbide mirrors, involves three chemical vapor deposition steps: one to produce the mirror faceplate, the second to form the lightweight backstructure which is deposited integral to the faceplate, and the third and final step which results in the deposition of a layer of optical grade material, for example, silicon, onto the front surface of the faceplate. The mirror figure and finish are fabricated into this latter material.

Atmospheric Pressure Plasma-Electrospin Hybrid Process for Protective Applications

NASA Astrophysics Data System (ADS)

Vitchuli Gangadharan, Narendiran

2011-12-01

Chemical and biological (C-B) warfare agents like sarin, sulfur mustard, anthrax are usually dispersed into atmosphere in the form of micro aerosols. They are considered to be dangerous weapon of mass destruction next to nuclear weapons. The airtight protective clothing materials currently available are able to stop the diffusion of threat agents but not good enough to detoxify them, which endangers the wearers. Extensive research efforts are being made to prepare advanced protective clothing materials that not only prevent the diffusion of C-B agents, but also detoxify them into harmless products thus ensuring the safety and comfort of the wearer. Electrospun nanofiber mats are considered to have effective filtration characteristics to stop the diffusion of submicron level particulates without sacrificing air permeability characteristics and could be used in protective application as barrier material. In addition, functional nanofibers could be potentially developed to detoxify the C-B warfare threats into harmless products. In this research, electrospun nanofibers were deposited on fabric surface to improve barrier efficiency without sacrificing comfort-related properties of the fabrics. Multi-functional nanofibers were fabricated through an electrospinning-electrospraying hybrid process and their ability to detoxify simulants of C-B agents was evaluated. Nanofibers were also deposited onto plasma-pretreated woven fabric substrate through a newly developed plasma-electrospinning hybrid process, to improve the adhesive properties of nanofibers on the fabric surface. The nanofiber adhesion and durability properties were evaluated by peel test, flex and abrasion resistance tests. In this research work, following tasks have been carried out: i) Controlled deposition of nanofiber mat onto woven fabric substrate Electrospun Nylon 6 fiber mats were deposited onto woven 50/50 Nylon/Cotton fabric with the motive of making them into protective material against submicron-level aerosol chemical and biological threats. Polymer solution concentration, electrospinning voltage, and deposition areal density were varied to establish the relationship of processing-structure-filtration efficiency for electrospun fiber mats. A high barrier efficiency of greater than 99.5% was achieved on electrospun fiber mats without sacrificing air permeability and pressure drop. ii) Fabrication and Characterization of Multifunctional ZnO/Nylon 6 nanofibers ZnO/Nylon 6 nanofiber mats were prepared by an electrospinning-electrospraying hybrid process, The electrospinning of polymer solution and electrospraying of ZnO particles were carried out simultaneously such that the ZnO nanoparticles were dispersed on the surface of Nylon 6 nanofibers. The prepared ZnO/Nylon 6 nanofiber mats were tested for detoxifying characteristics against simulants of C-B agents. The results showed that ZnO/Nylon 6 functional nanofiber mats exhibited good detoxification action against paraoxon and have antibacterial efficiency over 99.99% against both the gram-negative E. coli and gram positive B. cereus bacteria. iii) Improving adhesion of electrospun nanofiber mat onto woven fabric by plasma pretreatment of substrate fabric and plasma-electrospinning hybrid process Electrospun nanofibers were deposited onto plasma-pretreated woven fabric to improve the adhesion. In addition, the plasma-electrospinning hybrid process was developed and used in which the nanofibers were subjected to in-situ plasma treatment during electrospinning. The effects of plasma treatement on substrate fabric and electrospun fibers were characterized by water contact angle test, XPS analyses. The improvement of nanofiber adhesive properties on fabric substrate was evaluated by peel test, flex resistance test and abrasion resistance test. The test results showed that the plasma treatment caused introduction of active chemical groups on substrate fabric and electrospun nanofibers. These active chemical assisted in possible cross-linking formation between nanofiber mat and substrate fabric, and this hypothesis was supported by improved adhesion strength, flex resistance and abrasion resistance of nanofiber mat.

Process for fabrication of large titanium diboride ceramic bodies

DOEpatents

Moorhead, Arthur J.; Bomar, E. S.; Becher, Paul F.

1989-01-01

A process for manufacturing large, fully dense, high purity TiB.sub.2 articles by pressing powders with a sintering aid at relatively low temperatures to reduce grain growth. The process requires stringent temperature and pressure applications in the hot-pressing step to ensure maximum removal of sintering aid and to avoid damage to the fabricated article or the die.

Development of a low-cost, modified resin transfer molding process using elastomeric tooling and automated preform fabrication

NASA Technical Reports Server (NTRS)

Doane, William J.; Hall, Ronald G.

1992-01-01

This paper describes the design and process development of low-cost structural parts made by a modified resin transfer molding process. Innovative application of elastomeric tooling to increase laminate fiber volume and automated forming of fiber preforms are discussed, as applied to fabrication of a representative section of a cruise missile fuselage.

Silicon solar cells by ion implantation and pulsed energy processing

NASA Technical Reports Server (NTRS)

Kirkpatrick, A. R.; Minnucci, J. A.; Shaughnessy, T. S.; Greenwald, A. C.

1976-01-01

A new method for fabrication of silicon solar cells is being developed around ion implantation in conjunction with pulsed electron beam techniques to replace conventional furnace processing. Solar cells can be fabricated totally in a vacuum environment at room temperature. Cells with 10% AM0 efficiency have been demonstrated. High efficiency cells and effective automated processing capabilities are anticipated.

Fabricating optical phantoms to simulate skin tissue properties and microvasculatures

NASA Astrophysics Data System (ADS)

Sheng, Shuwei; Wu, Qiang; Han, Yilin; Dong, Erbao; Xu, Ronald

2015-03-01

This paper introduces novel methods to fabricate optical phantoms that simulate the morphologic, optical, and microvascular characteristics of skin tissue. The multi-layer skin-simulating phantom was fabricated by a light-cured 3D printer that mixed and printed the colorless light-curable ink with the absorption and the scattering ingredients for the designated optical properties. The simulated microvascular network was fabricated by a soft lithography process to embed microchannels in polydimethylsiloxane (PDMS) phantoms. The phantoms also simulated vascular anomalies and hypoxia commonly observed in cancer. A dual-modal multispectral and laser speckle imaging system was used for oxygen and perfusion imaging of the tissue-simulating phantoms. The light-cured 3D printing technique and the soft lithography process may enable freeform fabrication of skin-simulating phantoms that embed microvessels for image and drug delivery applications.

Attachment of Poly(l-lactide) Nanoparticles to Plasma-Treated Non-Woven Polymer Fabrics Using Inkjet Printing.

PubMed

Ivanova, Tatiana V; Baier, Grit; Landfester, Katharina; Musin, Eduard; Al-Bataineh, Sameer A; Cameron, David C; Homola, Tomáš; Whittle, Jason D; Sillanpää, Mika

2015-09-01

Active dressings that based on fabric materials are an area of interest for the treatment of wounds. Poly(l-lactide) nanoparticles containing the antimicrobial agent octenidine can be controllably lysed by toxins released by pathogenic bacteria thus releasing antimicrobial material in response to the presence of the bacterial toxins and so counteracting the infection. We developed an integrated engineering solution that allows for the stable immobilisation of nanoparticles on non-woven fabrics. The process involves coating nanoparticles on non-woven polymer surfaces by using an inkjet printing process. In order to improve the adhesion and retention of the nanoparticles on the fabric, surface pretreatment of the non-woven fabric using plasma jet treatment can be applied to increase its surface energy. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication of polymer micro-lens array with pneumatically diaphragm-driven drop-on-demand inkjet technology.

PubMed

Xie, Dan; Zhang, Honghai; Shu, Xiayun; Xiao, Junfeng

2012-07-02

The paper reports an effective method to fabricate micro-lens arrays with the ultraviolet-curable polymer, using an original pneumatically diaphragm-driven drop-on-demand inkjet system. An array of plano convex micro-lenses can be formed on the glass substrate due to surface tension and hydrophobic effect. The micro-lens arrays have uniform focusing function, smooth and real planar surface. The fabrication process showed good repeatability as well, fifty micro-lenses randomly selected form 9 × 9 miro-lens array with an average diameter of 333.28μm showed 1.1% variations. Also, the focal length, the surface roughness and optical property of the fabricated micro-lenses are measured, analyzed and proved satisfactory. The technique shows great potential for fabricating polymer micro-lens arrays with high flexibility, simple technological process and low production cost.

Facile preparation of porous alumina through-hole masks for sputtering by two-layer anodization

NASA Astrophysics Data System (ADS)

Yanagishita, Takashi; Masuda, Hideki

2016-08-01

Highly ordered porous alumina through-hole masks were fabricated on a substrate by combining two-layer anodization with subsequent through-holing by selective etching. This process allowed the fabrication of porous alumina masks without an increase in pore size during the etching performed for through-holing. Additionally, the process contributed to improved operability in the setting of the masks on substrates because the second anodizing layer acts as a supporting layer for the handling of the mask. The fabrication of ordered Au nanodot arrays was demonstrated as an example application of the through-hole masks obtained by the present process.

Electrochemical formation of field emitters

DOEpatents

Bernhardt, Anthony F.

1999-01-01

Electrochemical formation of field emitters, particularly useful in the fabrication of flat panel displays. The fabrication involves field emitting points in a gated field emitter structure. Metal field emitters are formed by electroplating and the shape of the formed emitter is controlled by the potential imposed on the gate as well as on a separate counter electrode. This allows sharp emitters to be formed in a more inexpensive and manufacturable process than vacuum deposition processes used at present. The fabrication process involves etching of the gate metal and the dielectric layer down to the resistor layer, and then electroplating the etched area and forming an electroplated emitter point in the etched area.

Electro-osmotic transport in wet processing of textiles

DOEpatents

Cooper, John F.

1998-01-01

Electro-osmotic (or electrokinetic) transport is used to efficiently force a solution (or water) through the interior of the fibers or yarns of textile materials for wet processing of textiles. The textile material is passed between electrodes that apply an electric field across the fabric. Used alone or in parallel with conventional hydraulic washing (forced convection), electro-osmotic transport greatly reduces the amount of water used in wet processing. The amount of water required to achieve a fixed level of rinsing of tint can be reduced, for example, to 1-5 lbs water per pound of fabric from an industry benchmark of 20 lbs water/lb fabric.

Demonstration of submicron square-like silicon waveguide using optimized LOCOS process.

PubMed

Desiatov, Boris; Goykhman, Ilya; Levy, Uriel

2010-08-30

We demonstrate the design, fabrication and experimental characterization of a submicron-scale silicon waveguide that is fabricated by local oxidation of silicon. The use of local oxidation process allows defining the waveguide geometry and obtaining smooth sidewalls. The process can be tuned to precisely control the shape and the dimensions of the waveguide. The fabricated waveguides are measured using near field scanning optical microscope at 1550 nm wavelength. These measurements show mode width of 0.4 µm and effective refractive index of 2.54. Finally, we demonstrate the low loss characteristics of our waveguide by imaging the light scattering using an infrared camera.

Electro-osmotic transport in wet processing of textiles

DOEpatents

Cooper, J.F.

1998-09-22

Electro-osmotic (or electrokinetic) transport is used to efficiently force a solution (or water) through the interior of the fibers or yarns of textile materials for wet processing of textiles. The textile material is passed between electrodes that apply an electric field across the fabric. Used alone or in parallel with conventional hydraulic washing (forced convection), electro-osmotic transport greatly reduces the amount of water used in wet processing. The amount of water required to achieve a fixed level of rinsing of tint can be reduced, for example, to 1--5 lbs water per pound of fabric from an industry benchmark of 20 lbs water/lb fabric. 5 figs.

Regenerated silk materials for functionalized silk orthopedic devices by mimicking natural processing

PubMed Central

Li, Chunmei; Hotz, Blake; Ling, Shengjie; Guo, Jin; Haas, Dylan S.; Marelli, Benedetto; Omenetto, Fiorenzo; Lin, Samuel J.; Kaplan, David L.

2016-01-01

Silk fibers spun by silkworms and spiders exhibit exceptional mechanical properties with a unique combination of strength, extensibility and toughness. In contrast, the mechanical properties of regenerated silk materials can be tuned through control of the fabrication process. Here we introduce a biomimetic, all-aqueous process, to obtain bulk regenerated silk-based materials for the fabrication of functionalized orthopedic devices. The silk materials generated in the process replicate the nano-scale structure of natural silk fibers and possess excellent mechanical properties. The biomimetic materials demonstrated excellent machinability, providing a path towards the fabrication of a new family of resorbable orthopedic devices where organic solvents are avoided, thus allowing functionalization with bioactive molecules to promote bone remodeling and integration. PMID:27697669

Advanced composites: Fabrication processes for selected resin matrix materials

NASA Technical Reports Server (NTRS)

Welhart, E. K.

1976-01-01

This design note is based on present state of the art for epoxy and polyimide matrix composite fabrication technology. Boron/epoxy and polyimide and graphite/epoxy and polyimide structural parts can be successfully fabricated. Fabrication cycles for polyimide matrix composites have been shortened to near epoxy cycle times. Nondestructive testing has proven useful in detecting defects and anomalies in composite structure elements. Fabrication methods and tooling materials are discussed along with the advantages and disadvantages of different tooling materials. Types of honeycomb core, material costs and fabrication methods are shown in table form for comparison. Fabrication limits based on tooling size, pressure capabilities and various machining operations are also discussed.

Isolation and recovery of cellulose from waste nylon/cotton blended fabrics by 1-allyl-3-methylimidazolium chloride.

PubMed

Lv, Fangbing; Wang, Chaoxia; Zhu, Ping; Zhang, Chuanjie

2015-06-05

Development of a simple process for separating cellulose and nylon 6 from their blended fabrics is indispensable for recycling of waste mixed fabrics. An efficient procedure of dissolution of the fabrics in an ionic liquid 1-allyl-3-methylimidazolium chloride ([AMIM]Cl) and subsequent filtration separation has been demonstrated. Effects of treatment temperature, time and waste fabrics ratio on the recovery rates were investigated. SEM images showed that the cotton cellulose dissolved in [AMIM]Cl while the nylon 6 fibers remained. The FTIR spectrum of regenerated cellulose (RC) was similar with that of virgin cotton fibers, which verified that no other chemical reaction occurred besides breakage of hydrogen bonds during the processes of dissolution and separation. TGA curves indicated that the regenerated cellulose possessed a reduced thermal stability and was effectively removed from waste nylon/cotton blended fabrics (WNCFs). WNCFs were sufficiently reclaimed with high recovery rate of both regenerated cellulose films and nylon 6 fibers. Copyright © 2015 Elsevier Ltd. All rights reserved.

Multiple pass and multiple layer friction stir welding and material enhancement processes

DOEpatents

Feng, Zhili [Knoxville, TN; David, Stan A [Knoxville, TN; Frederick, David Alan [Harriman, TN

2010-07-27

Processes for friction stir welding, typically for comparatively thick plate materials using multiple passes and multiple layers of a friction stir welding tool. In some embodiments a first portion of a fabrication preform and a second portion of the fabrication preform are placed adjacent to each other to form a joint, and there may be a groove adjacent the joint. The joint is welded and then, where a groove exists, a filler may be disposed in the groove, and the seams between the filler and the first and second portions of the fabrication preform may be friction stir welded. In some embodiments two portions of a fabrication preform are abutted to form a joint, where the joint may, for example, be a lap joint, a bevel joint or a butt joint. In some embodiments a plurality of passes of a friction stir welding tool may be used, with some passes welding from one side of a fabrication preform and other passes welding from the other side of the fabrication preform.

Conformal coating of amorphous silicon and germanium by high pressure chemical vapor deposition for photovoltaic fabrics

NASA Astrophysics Data System (ADS)

Ji, Xiaoyu; Cheng, Hiu Yan; Grede, Alex J.; Molina, Alex; Talreja, Disha; Mohney, Suzanne E.; Giebink, Noel C.; Badding, John V.; Gopalan, Venkatraman

2018-04-01

Conformally coating textured, high surface area substrates with high quality semiconductors is challenging. Here, we show that a high pressure chemical vapor deposition process can be employed to conformally coat the individual fibers of several types of flexible fabrics (cotton, carbon, steel) with electronically or optoelectronically active materials. The high pressure (˜30 MPa) significantly increases the deposition rate at low temperatures. As a result, it becomes possible to deposit technologically important hydrogenated amorphous silicon (a-Si:H) from silane by a simple and very practical pyrolysis process without the use of plasma, photochemical, hot-wire, or other forms of activation. By confining gas phase reactions in microscale reactors, we show that the formation of undesired particles is inhibited within the microscale spaces between the individual wires in the fabric structures. Such a conformal coating approach enables the direct fabrication of hydrogenated amorphous silicon-based Schottky junction devices on a stainless steel fabric functioning as a solar fabric.

COINS: A composites information database system

NASA Technical Reports Server (NTRS)

Siddiqi, Shahid; Vosteen, Louis F.; Edlow, Ralph; Kwa, Teck-Seng

1992-01-01

An automated data abstraction form (ADAF) was developed to collect information on advanced fabrication processes and their related costs. The information will be collected for all components being fabricated as part of the ACT program and include in a COmposites INformation System (COINS) database. The aim of the COINS development effort is to provide future airframe preliminary design and fabrication teams with a tool through which production cost can become a deterministic variable in the design optimization process. The effort was initiated by the Structures Technology Program Office (STPO) of the NASA LaRC to implement the recommendations of a working group comprised of representatives from the commercial airframe companies. The principal working group recommendation was to re-institute collection of composite part fabrication data in a format similar to the DOD/NASA Structural Composites Fabrication Guide. The fabrication information collection form was automated with current user friendly computer technology. This work in progress paper describes the new automated form and features that make the form easy to use by an aircraft structural design-manufacturing team.

Rapid wasted-free microfluidic fabrication based on ink-jet approach for microfluidic sensing applications

NASA Astrophysics Data System (ADS)

Jarujareet, Ungkarn; Amarit, Rattasart; Sumriddetchkajorn, Sarun

2016-11-01

Realizing that current microfluidic chip fabrication techniques are time consuming and labor intensive as well as always have material leftover after chip fabrication, this research work proposes an innovative approach for rapid microfluidic chip production. The key idea relies on a combination of a widely-used inkjet printing method and a heat-based polymer curing technique with an electronic-mechanical control, thus eliminating the need of masking and molds compared to typical microfluidic fabrication processes. In addition, as the appropriate amount of polymer is utilized during printing, there is much less amount of material wasted. Our inkjet-based microfluidic printer can print out the desired microfluidic chip pattern directly onto a heated glass surface, where the printed polymer is suddenly cured. Our proof-of-concept demonstration for widely-used single-flow channel, Y-junction, and T-junction microfluidic chips shows that the whole microfluidic chip fabrication process requires only 3 steps with a fabrication time of 6 minutes.

Cost-effective large-scale fabrication of diffractive optical elements by using conventional semiconducting processes.

PubMed

Yoo, Seunghwan; Song, Ho Young; Lee, Junghoon; Jang, Cheol-Yong; Jeong, Hakgeun

2012-11-20

In this article, we introduce a simple fabrication method for SiO(2)-based thin diffractive optical elements (DOEs) that uses the conventional processes widely used in the semiconductor industry. Photolithography and an inductively coupled plasma etching technique are easy and cost-effective methods for fabricating subnanometer-scale and thin DOEs with a refractive index of 1.45, based on SiO(2). After fabricating DOEs, we confirmed the shape of the output light emitted from the laser diode light source and applied to a light-emitting diode (LED) module. The results represent a new approach to mass-produce DOEs and realize a high-brightness LED module.

Theoretical and experimental research in space photovoltaics

NASA Technical Reports Server (NTRS)

Faur, Mircea; Faur, Maria

1995-01-01

Theoretical and experimental research is outlined for indium phosphide solar cells, other solar cells for space applications, fabrication and performance measurements of shallow homojunction InP solar cells for space applications, improved processing steps and InP material characterization with applications to fabrication of high efficiency radiation resistant InP solar cells and other opto-electronic InP devices, InP solar cells fabricated by thermal diffusion, experiment-based predicted high efficiency solar cells fabricated by closed-ampoule thermal diffusion, radiation resistance of diffused junction InP solar cells, chemical and electrochemical characterization and processing of InP diffused structures and solar cells, and progress in p(+)n InP diffused solar cells.

Fabrication technology

NASA Astrophysics Data System (ADS)

1988-05-01

Many laboratory programs continue to need optical components of ever-increasing size and accuracy. Unfortunately, optical surfaces produced by the conventional sequence of grinding, lapping, and polishing can become prohibitively expensive. Research in the Fabrication Technology area focuses on methods of fabricating components with heretofore unrealized levels of precision. In FY87, researchers worked to determine the fundamental mechanical limits of material removal, experimented with unique material removal and deposition processes, developed servo systems for controlling the geometric position of ultraprecise machine tools, and advanced the ability to precisely measure contoured workpieces. Continued work in these areas will lead to more cost-effective processes to fabricate even higher quality optical components for advanced lasers and for visible, ultraviolet, and X-ray diagnostic systems.

Nanoimprint lithography for nanodevice fabrication

NASA Astrophysics Data System (ADS)

Barcelo, Steven; Li, Zhiyong

2016-09-01

Nanoimprint lithography (NIL) is a compelling technique for low cost nanoscale device fabrication. The precise and repeatable replication of nanoscale patterns from a single high resolution patterning step makes the NIL technique much more versatile than other expensive techniques such as e-beam or even helium ion beam lithography. Furthermore, the use of mechanical deformation during the NIL process enables grayscale lithography with only a single patterning step, not achievable with any other conventional lithography techniques. These strengths enable the fabrication of unique nanoscale devices by NIL for a variety of applications including optics, plasmonics and even biotechnology. Recent advances in throughput and yield in NIL processes demonstrate the potential of being adopted for mainstream semiconductor device fabrication as well.

Development of Self-Cleaning Denim Fabrics

NASA Astrophysics Data System (ADS)

Uğur, Ş. S.; Sarıışık, A. M.; Çavuşlar, E.; Ertek, M.

2017-10-01

Denim fabrics coated with TiO2 nanolayers for self-cleaning properties by using a continuous layer-by-layer method. Nanolayer coated denim fabrics washed with an enzyme process for aging affect. Fabrics were analyzed with SEM-EDX and XPS measurements. Self-cleaning properties of the nanolayer deposited denim fabrics were tested according to red wine stain against to Suntest visible light irradiation after 72 h. And also, some physical (air permeability, tensile strength) and color (color difference and rubbing fastness) properties were evaluated.

Low cost fabrication of ablative heat shields

NASA Technical Reports Server (NTRS)

Cecka, A. M.; Schofield, W. C.

1972-01-01

A material and process study was performed using subscale panels in an attempt to reduce the cost of fabricating ablative heat shield panels. Although no improvements were made in the material formulation, a significant improvement was obtained in the processing methods compared to those employed in the previous work. The principal feature of the new method is the press filling and curing of the ablation material in a single step with the bonding and curing of the face sheet. This method was chosen to replace the hand troweling and autoclave curing procedure used previously. Double-curvature panels of the same size as the flat panels were fabricated to investigate fabrication problems. It was determined that the same materials and processes used for flat panels can be used to produce the curved panels. A design with severe curvatures consisting of radii of 24 x 48 inches was employed for evaluation. Ten low-density and ten high-density panels were fabricated. With the exception of difficulties related to short run non-optimum tooling, excellent panel filling and density uniformity were obtained.

Fabrication of fine-grain tantalum diffusion barrier tube for Nb3Sn conductors

NASA Astrophysics Data System (ADS)

Hartwig, K. T.; Balachandran, S.; Mezyenski, R.; Seymour, N.; Robinson, J.; Barber, R. E.

2014-01-01

Diffusion barriers used in Nb3Sn wire are often fabricated by wrapping Ta sheet into a tube with an overlap seam. A common result of such practice is non-uniform deformation in the Ta sheet as it thins by wire drawing because of non-uniform grain size and texture in the original Ta sheet. Seamless Ta tube with a fine-grain and uniform microstructure would be much better for the diffusion barrier application, but such material is expensive and difficult to manufacture. This report presents results on a new fabrication strategy for Ta tube that shows promise for manufacture of less costly tube with an improved microstructure. The fabrication method begins with seam-welded tube but gives a fine-grain uniform microstructure with little difference between the longitudinal seam weld region and the parent metal after post-weld processing. Severe plastic deformation processing (SPD) applied by area reduction extrusion and tube equal channel angular extrusion (tECAE) are used to refine and homogenize the microstructure. Microstructure and mechanical property results are presented for Ta tubes fabricated by this new processing strategy.

Detailed study of scratch drive actuator characteristics using high-speed imaging

NASA Astrophysics Data System (ADS)

Li, Lijie; Brown, James G.; Uttamchandani, Deepak G.

2001-10-01

Microactuators are one of the key components in MEMS and Microsystems technology, and various designs have been realized through different fabrication processes. One type of microactuator commonly used is the scratch drive actuator (SDA) that is frequently fabricated by surface micromachining processes. An experimental investigation has been conducted on the characteristics of SDAs fabricated using the Cronos Microsystems MUMPs process. The motivation is to compare the response of SDAs located on the same die, and SDAs located on the different dies from the same fabrication batch. A high-speed imaging camera has been used to precisely determine important SDA characteristics such as step size, velocity, maximum velocity, and acceleration over long travel distance. These measurements are important from a repeatability point of view, and in order to fully exploit the potential of the SDA as a precise positioning mechanism. 2- and 3-stage SDAs have been designed and fabricated for these experiments. Typical step sizes varying from 7 nm at a driving voltage of 60 V to 23 nm at 290 V have been obtained.

Fast Printing and In-Situ Morphology Observation of Organic Photovoltaics using Slot-Die Coating

NASA Astrophysics Data System (ADS)

Liu, Feng; Ferdous, Sunzida; Wang, Cheng; Hexamer, Alexander; Russell, Thomas; Cheng Wang Collaboration; Thomas Russell Team

2014-03-01

The solvent-processibility of polymer semiconductors is a key advantage for the fabrication of large area, organic bulk-heterojunction (BHJ) photovoltaic devices. Most reported power conversion efficiencies (PCE) are based on small active areas, fabricated by spin-coating technique. In general, this does not reflect device fabrication in an industrial setting. To realize commercial viability, devices need to be fabricated in a roll-to-roll fashion. The evolution of the morphology associated with different processing parameters, like solvent choice, concentration and temperature, needs to be understood and controlled. We developed a mini slot-die coater, to fabricate BHJ devices using various low band gap polymers mixed with phenyl-C71-butyric acid methyl ester (PCBM). Solvent choice, processing additives, coating rate and coating temperatures were used to control the final morphology. Efficiencies comparable to lab-setting spin-coated devices are obtained. The evolution of the morphology was monitored by in situ scattering measurements, detecting the onset of the polymer chain packing in solution that led to the formation of a fibrillar network in the film.

Modified Powder-in-Tube Technique Based on the Consolidation Processing of Powder Materials for Fabricating Specialty Optical Fibers

PubMed Central

Auguste, Jean-Louis; Humbert, Georges; Leparmentier, Stéphanie; Kudinova, Maryna; Martin, Pierre-Olivier; Delaizir, Gaëlle; Schuster, Kay; Litzkendorf, Doris

2014-01-01

The objective of this paper is to demonstrate the interest of a consolidation process associated with the powder-in-tube technique in order to fabricate a long length of specialty optical fibers. This so-called Modified Powder-in-Tube (MPIT) process is very flexible and paves the way to multimaterial optical fiber fabrications with different core and cladding glassy materials. Another feature of this technique lies in the sintering of the preform under reducing or oxidizing atmosphere. The fabrication of such optical fibers implies different constraints that we have to deal with, namely chemical species diffusion or mechanical stress due to the mismatches between thermal expansion coefficients and working temperatures of the fiber materials. This paper focuses on preliminary results obtained with a lanthano-aluminosilicate glass used as the core material for the fabrication of all-glass fibers or specialty Photonic Crystal Fibers (PCFs). To complete the panel of original microstructures now available by the MPIT technique, we also present several optical fibers in which metallic particles or microwires are included into a silica-based matrix. PMID:28788176

Nano-imprint gold grating as refractive index sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumari, Sudha; Mohapatra, Saswat; Moirangthem, Rakesh S.

Large scale of fabrication of plasmonic nanostructures has been a challenging task due to time consuming process and requirement of expensive nanofabrication tools such as electron beam lithography system, focused ion beam system, and extreme UV photolithography system. Here, we present a cost-effective fabrication technique so called soft nanoimprinting to fabricate nanostructures on the larger sample area. In our fabrication process, a commercially available optical DVD disc was used as a template which was imprinted on a polymer glass substrate to prepare 1D polymer nano-grating. A homemade nanoimprinting setup was used in this fabrication process. Further, a label-free refractive indexmore » sensor was developed by utilizing the properties of surface plasmon resonance (SPR) of a gold coated 1D polymer nano-grating. Refractive index sensing was tested by exposing different solutions of glycerol-water mixture on the surface of gold nano-grating. The calculated bulk refractive index sensitivity was found to be 751nm/RIU. We believed that our proposed SPR sensor could be a promising candidate for developing low-cost refractive index sensor with high sensitivity on a large scale.« less

Electronic Devices Based on Oxide Thin Films Fabricated by Fiber-to-Film Process.

PubMed

Meng, You; Liu, Ao; Guo, Zidong; Liu, Guoxia; Shin, Byoungchul; Noh, Yong-Young; Fortunato, Elvira; Martins, Rodrigo; Shan, Fukai

2018-05-30

Technical development for thin-film fabrication is essential for emerging metal-oxide (MO) electronics. Although impressive progress has been achieved in fabricating MO thin films, the challenges still remain. Here, we report a versatile and general thermal-induced nanomelting technique for fabricating MO thin films from the fiber networks, briefly called fiber-to-film (FTF) process. The high quality of the FTF-processed MO thin films was confirmed by various investigations. The FTF process is generally applicable to numerous technologically relevant MO thin films, including semiconducting thin films (e.g., In 2 O 3 , InZnO, and InZrZnO), conducting thin films (e.g., InSnO), and insulating thin films (e.g., AlO x ). By optimizing the fabrication process, In 2 O 3 /AlO x thin-film transistors (TFTs) were successfully integrated by fully FTF processes. High-performance TFT was achieved with an average mobility of ∼25 cm 2 /(Vs), an on/off current ratio of ∼10 7 , a threshold voltage of ∼1 V, and a device yield of 100%. As a proof of concept, one-transistor-driven pixel circuit was constructed, which exhibited high controllability over the light-emitting diodes. Logic gates based on fully FTF-processed In 2 O 3 /AlO x TFTs were further realized, which exhibited good dynamic logic responses and voltage amplification by a factor of ∼4. The FTF technique presented here offers great potential in large-area and low-cost manufacturing for flexible oxide electronics.

Preform Characterization in VARTM Process Model Development

NASA Technical Reports Server (NTRS)

Grimsley, Brian W.; Cano, Roberto J.; Hubert, Pascal; Loos, Alfred C.; Kellen, Charles B.; Jensen, Brian J.

2004-01-01

Vacuum-Assisted Resin Transfer Molding (VARTM) is a Liquid Composite Molding (LCM) process where both resin injection and fiber compaction are achieved under pressures of 101.3 kPa or less. Originally developed over a decade ago for marine composite fabrication, VARTM is now considered a viable process for the fabrication of aerospace composites (1,2). In order to optimize and further improve the process, a finite element analysis (FEA) process model is being developed to include the coupled phenomenon of resin flow, preform compaction and resin cure. The model input parameters are obtained from resin and fiber-preform characterization tests. In this study, the compaction behavior and the Darcy permeability of a commercially available carbon fabric are characterized. The resulting empirical model equations are input to the 3- Dimensional Infiltration, version 5 (3DINFILv.5) process model to simulate infiltration of a composite panel.

Demonstration of the feasibility of automated silicon solar cell fabrication

NASA Technical Reports Server (NTRS)

Taylor, W. E.; Schwartz, F. M.

1975-01-01

A study effort was undertaken to determine the process, steps and design requirements of an automated silicon solar cell production facility. Identification of the key process steps was made and a laboratory model was conceptually designed to demonstrate the feasibility of automating the silicon solar cell fabrication process. A detailed laboratory model was designed to demonstrate those functions most critical to the question of solar cell fabrication process automating feasibility. The study and conceptual design have established the technical feasibility of automating the solar cell manufacturing process to produce low cost solar cells with improved performance. Estimates predict an automated process throughput of 21,973 kilograms of silicon a year on a three shift 49-week basis, producing 4,747,000 hexagonal cells (38mm/side), a total of 3,373 kilowatts at an estimated manufacturing cost of $0.866 per cell or $1.22 per watt.

Effect of the preform fabrication process on the properties of all-silica optical fibres

NASA Astrophysics Data System (ADS)

Grishchenko, A. B.

2017-12-01

In this paper, we present a detailed comparison of technical capabilities of processes for the fabrication of all-silica optical fibre preforms with the use of an atmospheric pressure radio frequency plasma (POVD process) and low-pressure microwave plasma (PCVD process) and analyse the origin of the difference in optical properties between fibres produced by these methods. It is shown that the higher temperature of the core material and the higher oxygen partial pressure in preform fabrication by the POVD process lead to an increase in optical losses in the visible and UV spectral regions in the silica fibres with low hydroxyl (OH) content and a decrease in the solarisation resistance of the fibres with high OH content, i.e. to a more rapid increase in background losses in response to UV irradiation. No such drawbacks are detected in the case of the growth of reflective layers by the PCVD process.

Development and demonstration of manufacturing processes for fabricating graphite/Larc-160 polyimide structural elements, part 4, paragraph C

NASA Technical Reports Server (NTRS)

1981-01-01

Progress in the development of processes for production of Celion/LARC-160 graphite-polyimide materials, quality control methods, and the fabrication of Space Shuttle composite structure components is reported. The formulation and processing limits for three batches of resin are presented. Process improvements for simplification of the imidizing and autoclave cure cycles are described. Imidized and autoclave cured test panels were prepared. Celion/LARC-160 cure process verification and the fabrication of honeycomb sandwich panel elements and skin/stringer panels are described. C-scans of laminates imidized at 163 C to 218 C for periods from 30 to 180 minutes, and of process verification laminates made from different batches of prepreg are presented. Failure modes and load/strain characteristics of sandwich elements and C-scans of stringer to skin bond joints are also given.

Capillary-Driven Microfluidic Chips for Miniaturized Immunoassays: Efficient Fabrication and Sealing of Chips Using a "Chip-Olate" Process.

PubMed

Temiz, Yuksel; Delamarche, Emmanuel

2017-01-01

The fabrication of silicon-based microfluidic chips is invaluable in supporting the development of many microfluidic concepts for research in the life sciences and in vitro diagnostic applications such as the realization of miniaturized immunoassays using capillary-driven chips. While being extremely abundant, the literature covering microfluidic chip fabrication and assay development might not have addressed properly the challenge of fabricating microfluidic chips on a wafer level or the need for dicing wafers to release chips that need then to be further processed, cleaned, rinsed, and dried one by one. Here, we describe the "chip-olate" process wherein microfluidic structures are formed on a silicon wafer, followed by partial dicing, cleaning, and drying steps. Then, integration of reagents (if any) can be done, followed by lamination of a sealing cover. Breaking by hand the partially diced wafer yields individual chips ready for use.

Stretchable V2O5/PEDOT supercapacitors: a modular fabrication process and charging with triboelectric nanogenerators.

PubMed

Qi, Ruijie; Nie, Jinhui; Liu, Mingyang; Xia, Mengyang; Lu, Xianmao

2018-04-26

Stretchable energy storage devices are of great importance for the viable applications of wearable/stretchable electronics. Studies on stretchable energy storage devices, especially supercapacitors (SCs), have shown encouraging progress. However, challenges still remain in the pursuit of high specific capacitances and facile fabrication methods. Herein, we report a modular materials fabrication and assembly process for stretchable SCs. With a V2O5/PEDOT composite as the active material, the resulting stretchable SCs exhibited high areal specific capacitances up to 240 mF cm-2 and good capacitance retention at a strain of 50%. To demonstrate the facile assembly process, a stretchable wristband was fabricated by simply assembling SC cells in series to deliver a voltage higher than 2 V. Charging the wristband with a triboelectric nanogenerator (TENG) to light an LED was further demonstrated, indicating the potential to integrate our SCs with environmental energy harvesters for self-powered stretchable devices.

A 4H Silicon Carbide Gate Buffer for Integrated Power Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ericson, N; Frank, S; Britton, C

2014-02-01

A gate buffer fabricated in a 2-mu m 4H silicon carbide (SiC) process is presented. The circuit is composed of an input buffer stage with a push-pull output stage, and is fabricated using enhancement mode N-channel FETs in a process optimized for SiC power switching devices. Simulation and measurement results of the fabricated gate buffer are presented and compared for operation at various voltage supply levels, with a capacitive load of 2 nF. Details of the design including layout specifics, simulation results, and directions for future improvement of this buffer are presented. In addition, plans for its incorporation into anmore » isolated high-side/low-side gate-driver architecture, fully integrated with power switching devices in a SiC process, are briefly discussed. This letter represents the first reported MOSFET-based gate buffer fabricated in 4H SiC.« less

Low-temperature deposition manufacturing: A novel and promising rapid prototyping technology for the fabrication of tissue-engineered scaffold.

PubMed

Liu, Wei; Wang, Daming; Huang, Jianghong; Wei, You; Xiong, Jianyi; Zhu, Weimin; Duan, Li; Chen, Jielin; Sun, Rong; Wang, Daping

2017-01-01

Developed in recent years, low-temperature deposition manufacturing (LDM) represents one of the most promising rapid prototyping technologies. It is not only based on rapid deposition manufacturing process but also combined with phase separation process. Besides the controlled macropore size, tissue-engineered scaffold fabricated by LDM has inter-connected micropores in the deposited lines. More importantly, it is a green manufacturing process that involves non-heating liquefying of materials. It has been employed to fabricate tissue-engineered scaffolds for bone, cartilage, blood vessel and nerve tissue regenerations. It is a promising technology in the fabrication of tissue-engineered scaffold similar to ideal scaffold and the design of complex organs. In the current paper, this novel LDM technology is introduced, and its control parameters, biomedical applications and challenges are included and discussed as well. Copyright © 2016 Elsevier B.V. All rights reserved.

Bio-inspired piezoelectric artificial hair cell sensor fabricated by powder injection molding

NASA Astrophysics Data System (ADS)

Han, Jun Sae; Oh, Keun Ha; Moon, Won Kyu; Kim, Kyungseop; Joh, Cheeyoung; Seo, Hee Seon; Bollina, Ravi; Park, Seong Jin

2015-12-01

A piezoelectric artificial hair cell sensor was fabricated by the powder injection molding process in order to make an acoustic vector hydrophone. The entire process of powder injection molding was developed and optimized for PMN-PZT ceramic powder. The artificial hair cell sensor, which consists of high aspect ratio hair cell and three rectangular mechanoreceptors, was precisely fabricated through the developed powder injection molding process. The density and the dielectric property of the fabricated sensor shows 98% of the theoretical density and 85% of reference dielectric property of PMN-PZT ceramic powder. With regard to homogeneity, three rectangular mechanoreceptors have the same dimensions, with 3 μm of tolerance with 8% of deviation of dielectric property. Packaged vector hydrophones measure the underwater acoustic signals from 500 to 800 Hz with -212 dB of sensitivity. Directivity of vector hydrophone was acquired at 600 Hz as analyzing phase differences of electric signals.

Applications of Micro/Nanoparticles in Microfluidic Sensors: A Review

PubMed Central

Jiang, Yusheng; Wang, Hui; Li, Shunbo; Wen, Weijia

2014-01-01

This paper reviews the applications of micro/nanoparticles in microfluidics device fabrication and analytical processing. In general, researchers have focused on two properties of particles—electric behavior and magnetic behavior. The applications of micro/nanoparticles could be summarized on the chip fabrication level and on the processing level. In the fabrication of microfluidic chips (chip fabrication level), particles are good additives in polydimethylsiloxane (PDMS) to prepare conductive or magnetic composites which have wide applications in sensors, valves and actuators. On the other hand, particles could be manipulated according to their electric and magnetic properties under external electric and magnetic fields when they are travelling in microchannels (processing level). Researchers have made a great progress in preparing modified PDMS and investigating the behaviors of particles in microchannels. This article attempts to present a discussion on the basis of particles applications in microfluidics. PMID:24755517

Improvements in purification of silver nanowires by decantation and fabrication of flexible transparent electrodes. Application to capacitive touch sensors.

PubMed

Mayousse, Céline; Celle, Caroline; Moreau, Eléonore; Mainguet, Jean-François; Carella, Alexandre; Simonato, Jean-Pierre

2013-05-31

Transparent flexible electrodes made of metallic nanowires, and in particular silver nanowires (AgNWs), appear as an extremely promising alternative to transparent conductive oxides for future optoelectronic devices. Though significant progresses have been made the last few years, there is still some room for improvement regarding the synthesis of high quality silver nanowire solutions and fabrication process of high performance electrodes. We show that the commonly used purification process can be greatly simplified through decantation. Using this process it is possible to fabricate flexible electrodes by spray coating with sheet resistance lower than 25 Ω sq⁻¹ at 90% transparency in the visible spectrum. These electrodes were used to fabricate an operative transparent flexible touch screen. To our knowledge this is the first reported AgNW based touch sensor relying on capacitive technology.

Toward practical all-solid-state lithium-ion batteries with high energy density and safety: Comparative study for electrodes fabricated by dry- and slurry-mixing processes

NASA Astrophysics Data System (ADS)

Nam, Young Jin; Oh, Dae Yang; Jung, Sung Hoo; Jung, Yoon Seok

2018-01-01

Owing to their potential for greater safety, higher energy density, and scalable fabrication, bulk-type all-solid-state lithium-ion batteries (ASLBs) employing deformable sulfide superionic conductors are considered highly promising for applications in battery electric vehicles. While fabrication of sheet-type electrodes is imperative from the practical point of view, reports on relevant research are scarce. This might be attributable to issues that complicate the slurry-based fabrication process and/or issues with ionic contacts and percolation. In this work, we systematically investigate the electrochemical performance of conventional dry-mixed electrodes and wet-slurry fabricated electrodes for ASLBs, by varying the different fractions of solid electrolytes and the mass loading. This information calls for a need to develop well-designed electrodes with better ionic contacts and to improve the ionic conductivity of solid electrolytes. As a scalable proof-of-concept to achieve better ionic contacts, a premixing process for active materials and solid electrolytes is demonstrated to significantly improve electrochemical performance. Pouch-type 80 × 60 mm2 all-solid-state LiNi0·6Co0·2Mn0·2O2/graphite full-cells fabricated by the slurry process show high cell-based energy density (184 W h kg-1 and 432 W h L-1). For the first time, their excellent safety is also demonstrated by simple tests (cutting with scissors and heating at 110 °C).

A low-cost fabrication method for sub-millimeter wave GaAs Schottky diode

NASA Astrophysics Data System (ADS)

Jenabi, Sarvenaz; Deslandes, Dominic; Boone, Francois; Charlebois, Serge A.

2017-10-01

In this paper, a submillimeter-wave Schottky diode is designed and simulated. Effect of Schottky layer thickness on cut-off frequency is studied. A novel microfabrication process is proposed and implemented. The presented microfabrication process avoids electron-beam (e-beam) lithography which reduces the cost. Also, this process provides more flexibility in selection of design parameters and allows significant reduction in the device parasitic capacitance. A key feature of the process is that the Schottky contact, the air-bridges, and the transmission lines, are fabricated in a single lift-off step. This process relies on a planarization method that is suitable for trenches of 1-10 μm deep and is tolerant to end-point variations. The fabricated diode is measured and results are compared with simulations. A very good agreement between simulation and measurement results are observed.

Fabrication Process for Large Size Mold and Alignment Method for Nanoimprint System

NASA Astrophysics Data System (ADS)

Ishibashi, Kentaro; Kokubo, Mitsunori; Goto, Hiroshi; Mizuno, Jun; Shoji, Shuichi

Nanoimprint technology is considered one of the mass production methods of the display for cellular phone or notebook computer, with Anti-Reflection Structures (ARS) pattern and so on. In this case, the large size mold with nanometer order pattern is very important. Then, we describe the fabrication process for large size mold, and the alignment method for UV nanoimprint system. We developed the original mold fabrication process using nanoimprint method and etching techniques. In 66 × 45 mm2 area, 200nm period seamless patterns were formed using this process. And, we constructed original alignment system that consists of the CCD-camera system, X-Y-θ table, method of moiré fringe, and image processing system, because the accuracy of pattern connection depends on the alignment method. This alignment system accuracy was within 20nm.

Interphase layer optimization for metal matrix composites with fabrication considerations

NASA Technical Reports Server (NTRS)

Morel, M.; Saravanos, D. A.; Chamis, C. C.

1991-01-01

A methodology is presented to reduce the final matrix microstresses for metal matrix composites by concurrently optimizing the interphase characteristics and fabrication process. Application cases include interphase tailoring with and without fabrication considerations for two material systems, graphite/copper and silicon carbide/titanium. Results indicate that concurrent interphase/fabrication optimization produces significant reductions in the matrix residual stresses and strong coupling between interphase and fabrication tailoring. The interphase coefficient of thermal expansion and the fabrication consolidation pressure are the most important design parameters and must be concurrently optimized to further reduce the microstresses to more desirable magnitudes.

A patterned ZnO nanorod array/gas sensor fabricated by mechanoelectrospinning-assisted selective growth.

PubMed

Wang, Xiaomei; Sun, Fazhe; Huang, Yongan; Duan, Yongqing; Yin, Zhouping

2015-02-21

Micropatterned ZnO nanorod arrays were fabricated by the mechanoelectrospinning-assisted direct-writing process and the hydrothermal growth process, and utilized as gas sensors that exhibited excellent Ohmic behavior and sensitivity response to oxidizing gas NO2 at low concentrations (1-100 ppm).

Energy Systems Fabrication Laboratory | Energy Systems Integration Facility

Science.gov Websites

Fabrication The fuel cell fabrication hub includes laboratory spaces with local exhaust and chemical fume hoods that support electrolysis and other chemical process research. Key Infrastructure Perchloric acid washdown hood, local exhaust, specialty gas manifolding, deionized water, chemical fume hoods, glassware

Development and fabrication of a solar cell junction processing system

NASA Technical Reports Server (NTRS)

Kiesling, R.

1981-01-01

The major component fabrication program was completed. Assembly and system testing of the pulsed electron beam annealing machine are described. The design program for the transport reached completion, and the detailed drawings were released for fabrication and procurement of the long lead time components.

Mechanical behavior of post-processed Inconel 718 manufactured through the electron beam melting process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirka, Michael M.; Medina, Frank; Dehoff, Ryan R.

Here, the electron beam melting (EBM) process was used to fabricate Inconel 718. The microstructure and tensile properties were characterized in both the as-fabricated and post-processed state transverse (T-orientation) and longitudinal (L-orientation) to the build direction. Post-processing involved both a hot isostatic pressing (HIP) and solution treatment and aging (STA) to homogenize the microstructure. In the as-fabricated state, EBM Inconel 718 exhibits a spatially dependent microstructure that is a function of build height. Spanning the last few layers is a cored dendritic structure comprised of the products (carbides and Laves phase) predicted under equilibrium solidification conditions. With increasing distance frommore » the build's top surface, the cored dendritic structure becomes increasingly homogeneous with complete dissolution of the secondary dendrite arms. Further, temporal phase kinetics are observed to lead to the dissolution of the strengthening γ"γ" and precipitation of networks of fine δ needles that span the grains. Microstructurally, post-processing resulted in dissolution of the δ networks and homogeneous precipitation of γ'"γ'" throughout the height of the build. In the as-fabricated state, the monotonic tensile behavior exhibits a height sensitivity within the T-orientation at both 20 and 650 °C. Along the L-orientation, the tensile behavior exhibits strength values comparable to the reference wrought material in the fully heat-treated state. After post-processing, the yield strength, ultimate strength, and elongation at failure for the EBM Inconel 718 were observed to have beneficially increased compared to the as-fabricated material. Further, as a result of post-processing the spatial variance of the ultimate yield strength and elongation at failure within the transverse direction decreased by 4 and 3× respectively.« less

Mechanical behavior of post-processed Inconel 718 manufactured through the electron beam melting process

DOE PAGES

Kirka, Michael M.; Medina, Frank; Dehoff, Ryan R.; ...

2016-10-21

Here, the electron beam melting (EBM) process was used to fabricate Inconel 718. The microstructure and tensile properties were characterized in both the as-fabricated and post-processed state transverse (T-orientation) and longitudinal (L-orientation) to the build direction. Post-processing involved both a hot isostatic pressing (HIP) and solution treatment and aging (STA) to homogenize the microstructure. In the as-fabricated state, EBM Inconel 718 exhibits a spatially dependent microstructure that is a function of build height. Spanning the last few layers is a cored dendritic structure comprised of the products (carbides and Laves phase) predicted under equilibrium solidification conditions. With increasing distance frommore » the build's top surface, the cored dendritic structure becomes increasingly homogeneous with complete dissolution of the secondary dendrite arms. Further, temporal phase kinetics are observed to lead to the dissolution of the strengthening γ"γ" and precipitation of networks of fine δ needles that span the grains. Microstructurally, post-processing resulted in dissolution of the δ networks and homogeneous precipitation of γ'"γ'" throughout the height of the build. In the as-fabricated state, the monotonic tensile behavior exhibits a height sensitivity within the T-orientation at both 20 and 650 °C. Along the L-orientation, the tensile behavior exhibits strength values comparable to the reference wrought material in the fully heat-treated state. After post-processing, the yield strength, ultimate strength, and elongation at failure for the EBM Inconel 718 were observed to have beneficially increased compared to the as-fabricated material. Further, as a result of post-processing the spatial variance of the ultimate yield strength and elongation at failure within the transverse direction decreased by 4 and 3× respectively.« less

A three-mask process for fabricating vacuum-sealed capacitive micromachined ultrasonic transducers using anodic bonding.

PubMed

Yamaner, F Yalçın; Zhang, Xiao; Oralkan, Ömer

2015-05-01

This paper introduces a simplified fabrication method for vacuum-sealed capacitive micromachined ultrasonic transducer (CMUT) arrays using anodic bonding. Anodic bonding provides the established advantages of wafer-bondingbased CMUT fabrication processes, including process simplicity, control over plate thickness and properties, high fill factor, and ability to implement large vibrating cells. In addition to these, compared with fusion bonding, anodic bonding can be performed at lower processing temperatures, i.e., 350°C as opposed to 1100°C; surface roughness requirement for anodic bonding is more than 10 times more relaxed, i.e., 5-nm rootmean- square (RMS) roughness as opposed to 0.5 nm for fusion bonding; anodic bonding can be performed on smaller contact area and hence improves the fill factor for CMUTs. Although anodic bonding has been previously used for CMUT fabrication, a CMUT with a vacuum cavity could not have been achieved, mainly because gas is trapped inside the cavities during anodic bonding. In the approach we present in this paper, the vacuum cavity is achieved by opening a channel in the plate structure to evacuate the trapped gas and subsequently sealing this channel by conformal silicon nitride deposition in the vacuum environment. The plate structure of the fabricated CMUT consists of the single-crystal silicon device layer of a silicon-on-insulator wafer and a thin silicon nitride insulation layer. The presented fabrication approach employs only three photolithographic steps and combines the advantages of anodic bonding with the advantages of a patterned metal bottom electrode on an insulating substrate, specifically low parasitic series resistance and low parasitic shunt capacitance. In this paper, the developed fabrication scheme is described in detail, including process recipes. The fabricated transducers are characterized using electrical input impedance measurements in air and hydrophone measurements in immersion. A representative design is used to demonstrate immersion operation in conventional, collapse-snapback, and collapse modes. In collapsemode operation, an output pressure of 1.67 MPa pp is shown at 7 MHz on the surface of the transducer for 60-Vpp, 3-cycle sinusoidal excitation at 30-V dc bias.

Heater Validation for the NEXT-C Hollow Cathodes

NASA Technical Reports Server (NTRS)

Verhey, Timothy R.; Soulas, George C.; Mackey, Jonathan A.

2018-01-01

Swaged cathode heaters whose design was successfully demonstrated under a prior flight project are to be provided by the NASA Glenn Research Center for the NEXT-C ion thruster being fabricated by Aerojet Rocketdyne. Extensive requalification activities were performed to validate process controls that had to be re-established or revised because systemic changes prevented reuse of the past approaches. A development batch of heaters was successfully fabricated based on the new process controls. Acceptance and cyclic life testing of multiple discharge and neutralizer sized heaters extracted from the development batch was initiated in August, 2016, with the last heater completing testing in April, 2017. Cyclic life testing results substantially exceeded the NEXT-C thruster requirement as well as all past experience for GRC-fabricated units. The heaters demonstrated ultimate cyclic life capability of 19050 to 33500 cycles. A qualification batch of heaters is now being fabricated using the finalized process controls. A set of six heaters will be acceptance and cyclic tested to verify conformance to the behavior observed with the development heaters. The heaters for flight use will be then be provided to the contractor from the remainder of the qualification batch. This paper summarizes the fabrication process control activities and the acceptance and life testing of the development heater units.

Fabrication of polyimide based microfluidic channels for biosensor devices

NASA Astrophysics Data System (ADS)

Zulfiqar, Azeem; Pfreundt, Andrea; Svendsen, Winnie Edith; Dimaki, Maria

2015-03-01

The ever-increasing complexity of the fabrication process of Point-of-care (POC) devices, due to high demand of functional versatility, compact size and ease-of-use, emphasizes the need of multifunctional materials that can be used to simplify this process. Polymers, currently in use for the fabrication of the often needed microfluidic channels, have limitations in terms of their physicochemical properties. Therefore, the use of a multipurpose biocompatible material with better resistance to the chemical, thermal and electrical environment, along with capability of forming closed channel microfluidics is inevitable. This paper demonstrates a novel technique of fabricating microfluidic devices using polyimide (PI) which fulfills the aforementioned properties criteria. A fabrication process to pattern microfluidic channels, using partially cured PI, has been developed by using a dry etching method. The etching parameters are optimized and compared to those used for fully cured PI. Moreover, the formation of closed microfluidic channel on wafer level by bonding two partially cured PI layers or a partially cured PI to glass with high bond strength has been demonstrated. The reproducibility in uniformity of PI is also compared to the most commonly used SU8 polymer, which is a near UV sensitive epoxy resin. The potential applications of PI processing are POC and biosensor devices integrated with microelectronics.

New Comprehensive System to Construct Speleothem Fabrics Time Series

NASA Astrophysics Data System (ADS)

Frisia, S.; Borsato, A.

2014-12-01

Speleothem fabrics record processes that influence the way geochemical proxy data are encoded in speleothems, yet, there has been little advance in the use of fabrics as a complement to palaeo-proxy datasets since the fabric classification proposed by us in 2010. The systematic use of fabrics documentation in speleothem science has been limited by the absence of a comprehensive, numerical system that would allow constructing fabric time series comparable with the widely used geochemical time series. Documentation of speleothem fabrics is fundamental for a robust interpretation of speleothem time series where stable isotopes and trace elements are used as proxy, because fabrics highlight depositional as well as post-depositional processes whose understanding complements reconstructions based on geochemistry. Here we propose a logic system allowing transformation of microscope observations into numbers tied to acronyms that specify each fabric type and subtype. The rationale for ascribing progressive numbers to fabrics is based on the most up-to-date growth models. In this conceptual framework, the progression reflects hydrological conditions, bio-mediation and diagenesis. The lowest numbers are given to calcite fabrics formed at relatively constant drip rates: the columnar types (compact and open). Higher numbers are ascribed to columnar fabrics characterized by presence of impurities that cause elongation or lattice distortion (Elongated, Fascicular Optic and Radiaxial calcites). The sequence progresses with the dendritic fabrics, followed by micrite (M), which has been observed in association with microbial films. Microsparite (Ms) and mosaic calcite (Mc) have the highest numbers, being considered as diagenetic. Acronyms and subfixes are intended to become universally acknowledged. Thus, fabrics can be plotted vs. age to yield time series, where numbers are replaced by the acronyms. This will result in a visual representation of climate- or environmental-related parameters underpinning speleothem crystal growth. The Fabric log thus becomes a useful tool providing robustness to the geochemical data or test the overall utility of the speleothem record.

Fabrication of superhydrophobic cotton fabrics using crosslinking polymerization method

NASA Astrophysics Data System (ADS)

Jiang, Bin; Chen, Zhenxing; Sun, Yongli; Yang, Huawei; Zhang, Hongjie; Dou, Haozhen; Zhang, Luhong

2018-05-01

With the aim of removing and recycling oil and organic solvent from water, a facile and low-cost crosslinking polymerization method was first applied on surface modification of cotton fabrics for water/oil separation. Micro-nano hierarchical rough structure was constructed by triethylenetetramine (TETA) and trimesoyl chloride (TMC) that formed a polymeric layer on the surface of the fabric and anchored Al2O3 nanoparticles firmly between the fabric surface and the polymer layer. Superhydrophobic property was further obtained through self-assembly grafting of hydrophobic groups on the rough surface. The as-prepared cotton fabric exhibited superoleophilicity in atmosphere and superhydrophobicity both in atmosphere and under oil with the water contact angle of 153° and 152° respectively. Water/oil separation test showed that the as-prepared cotton fabric can handle with various oil-water mixtures with a high separation efficiency over 99%. More importantly, the separation efficiency remained above 98% over 20 cycles of reusing without losing its superhydrophobicity which demonstrated excellent reusability in oil/water separation process. Moreover, the as-prepared cotton fabric possessed good contamination resistance ability and self-cleaning property. Simulation washing process test showed the superhydrophobic cotton fabric maintained high value of water contact angle above 150° after 100 times washing, indicating great stability and durability. In summary, this work provides a brand-new way to surface modification of cotton fabric and makes it a promising candidate material for oil/water separation.

Synthesis of nano silver on cellulosic denim fabric producing yellow colored garment with antibacterial properties.

PubMed

Maryan, Ali Sadeghian; Montazer, Majid; Harifi, Tina

2015-01-22

In this study, an aged-look denim fabric with antibacterial property was prepared in one single step process. For this purpose, the simultaneous antibacterial finishing and discoloration of denim fabric was carried out through reduction of indigo dye and silver nitrate by glucose in alkaline media using a conventional garment washing machine. The uniform distribution of silver nanoparticles on the fiber surface was confirmed by scanning electron microscope and energy dispersive X-ray spectroscopy. The treated fabrics were also characterized by X-ray diffraction (XRD) and Raman spectroscopy. Due to the color changes during the process, the color coordinates of the treated samples were also measured. Findings suggest the potential of the proposed method in producing old-look denim fabric with desirable yellow appearance and reasonable antibacterial activity against Staphylococcus aureus and Escherichia coli with low toxicity for human. Copyright © 2014 Elsevier Ltd. All rights reserved.

Crashworthiness Assessment of Auto-body Members Considering the Fabrication Histories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huh, Hoon; Song, Jung-Han; Kim, Kee-Poong

2005-08-05

This paper is concerned with crashworthiness of auto-body members considering the effect of fabrication. Most auto-body members are fabricated with sheet metal forming process and welding process that induce fabrication histories such as the plastic work hardening, non-uniform thickness distribution and residual stress. Crash simulation is carried out for auto-body members with LS-DYNA3D in order to identify the fabrication effect on the crashworthiness. The analysis calculated crash mode, the reaction force and the energy absorption for crashworthiness assessment with the forming effect. The result shows that the crash analysis with considering the forming history leads to a different result frommore » that without considering the forming effect. The analysis results demonstrate that the design of auto-body members should be carried out considering the forming history for accurate assessment of the crashworthiness.« less

Fabrication of micro/nano-structures by electrohydrodynamic jet technique

NASA Astrophysics Data System (ADS)

Wang, Dazhi; Zhao, Xiaojun; Lin, Yigao; Ren, Tongqun; Liang, Junsheng; Liu, Chong; Wang, Liding

2017-12-01

Electrohydrodynamic jet (E-Jet) is an approach to the fabrication of micro/nano-structures by the use of electrical forces. In this process, the liquid is subjected to electrical and mechanical forces to form a liquid jet, which is further disintegrated into droplets. The major advantage of the E-Jet technique is that the sizes of the jet formed can be at the nanoscale far smaller than the nozzle size, which can realize high printing resolution with less risk of nozzle blockage. The E-Jet technique, which mainly includes E-Jet deposition and E-Jet printing, has a wide range of applications in the fabrication of micro/nano-structures for micro/nano-electromechanical system devices. This technique is also considered a micro/nano-fabrication method with a great potential for commercial use. This study mainly reviews the E-Jet deposition/printing fundamentals, fabrication process, and applications.

2D all-solid state fabric supercapacitor fabricated via an all solution process for use in smart textiles

NASA Astrophysics Data System (ADS)

Jang, Yunseok; Jo, Jeongdai; Woo, Kyoohee; Lee, Seung-Hyun; Kwon, Sin; Kim, Kwang-Young; Kang, Dongwoo

2017-05-01

We propose a method to fabricate a supercapacitor for smart textiles using silver (Ag) nanoparticle (NP) ink, simple spray patterning systems, and intense pulsed light (IPL) sintering systems. The Ag NP current collectors provided as high conductivity as the metal current collectors. The spray patterning technique is useful for fabricating supercapacitors because it is simple, fast, and cheap. IPL systems reduced the sintering temperature of Ag NPs and prevented thermal damage to the textiles during the Ag NP sintering process. The two-dimensional (2D) all-solid state fabric supercapacitor with an interdigitated configuration, developed here, exhibited a specific capacitance of 25.7 F/g and an energy density of 1.5 Wh/kg at a power density of 64.3 W/kg. These results support the utility of our proposed method in the development of energy textiles.

Powder-Coated Towpreg: Avenues to Near Net Shape Fabrication of High Performance Composites

NASA Technical Reports Server (NTRS)

Johnston, N. J.; Cano, R. J.; Marchello, J. M.; Sandusky, D. A.

1995-01-01

Near net shape parts were fabricated from powder-coated preforms. Key issues including powder loss during weaving and tow/tow friction during braiding were addressed, respectively, by fusing the powder to the fiber prior to weaving and applying a water-based gel to the towpreg prior to braiding. A 4:1 debulking of a complex 3-D woven powder-coated preform was achieved in a single step utilizing expansion rubber molding. Also, a process was developed for using powder-coated towpreg to fabricate consolidated ribbon having good dimensional integrity and low voids. Such ribbon will be required for in situ fabrication of structural components via heated head advanced tow placement. To implement process control and ensure high quality ribbon, the ribbonizer heat transfer and pulling force were modeled from fundamental principles. Most of the new ribbons were fabricated from dry polyarylene ether and polymide powders.

Flexible, FEP-Teflon covered solar cell module development

NASA Technical Reports Server (NTRS)

Rauschenbach, H. S.; Cannady, M. D.

1976-01-01

Techniques and equipment were developed for the large scale, low-cost fabrication of lightweight, roll-up and fold-up, FEP-Teflon encapsulated solar cell modules. Modules were fabricated by interconnecting solderless single-crystal silicon solar cells and heat laminating them at approximately 300 C between layers of optically clear FEP and to a loadbearing Kapton substrate sheet. Modules were fabricated from both conventional and wraparound contact solar cells. A heat seal technique was developed for mechanically interconnecting modules into an array. The electrical interconnections for both roll-up and fold-up arrays were also developed. The use of parallel-gap resistance welding, ultrasonic bonding, and thermocompression bonding processes for attaching interconnects to solar cells were investigated. Parallel-gap welding was found to be best suited for interconnecting the solderless solar cells into modules. Details of the fabrication equipment, fabrication processes, module and interconnect designs, environmental test equipment, and test results are presented.

Selective Plasma Deposition of Fluorocarbon Films on SAMs

NASA Technical Reports Server (NTRS)

Crain, Mark M., III; Walsh, Kevin M.; Cohn, Robert W.

2006-01-01

A dry plasma process has been demonstrated to be useful for the selective modification of self-assembled monolayers (SAMs) of alkanethiolates. These SAMs are used, during the fabrication of semiconductor electronic devices, as etch masks on gold layers that are destined to be patterned and incorporated into the devices. The selective modification involves the formation of fluorocarbon films that render the SAMs more effective in protecting the masked areas of the gold against etching by a potassium iodide (KI) solution. This modification can be utilized, not only in the fabrication of single electronic devices but also in the fabrication of integrated circuits, microelectromechanical systems, and circuit boards. In the steps that precede the dry plasma process, a silicon mold in the desired pattern is fabricated by standard photolithographic techniques. A stamp is then made by casting polydimethylsiloxane (commonly known as silicone rubber) in the mold. The stamp is coated with an alkanethiol solution, then the stamp is pressed on the gold layer of a device to be fabricated in order to deposit the alkanethiol to form an alkanethiolate SAM in the desired pattern (see figure). Next, the workpiece is exposed to a radio-frequency plasma generated from a mixture of CF4 and H2 gases. After this plasma treatment, the SAM is found to be modified, while the exposed areas of gold remain unchanged. This dry plasma process offers the potential for forming masks superior to those formed in a prior wet etching process. Among the advantages over the wet etching process are greater selectivity, fewer pin holes in the masks, and less nonuniformity of the masks. The fluorocarbon films formed in this way may also be useful as intermediate layers for subsequent fabrication steps and as dielectric layers to be incorporated into finished products.

Anti-flammable properties of cotton fabrics using eco friendly inorganic materials by layering self-assisted processing

USDA-ARS?s Scientific Manuscript database

A flame retardant surface has been prepared by the layer-by layer assemblies of branched polyethylenimine (BPEI), kaolin, urea, diammonium phosphate (dibasic) on cotton fabrics. Four different kinds of cotton fabrics (print cloth, mercerized print cloth, mercerized twill, and fleece) were prepared ...

Fabrication of graphite/epoxy cases for orbit insertion motors

NASA Technical Reports Server (NTRS)

Schmidt, W. W.

1973-01-01

The fabrication procedures are described for filament-wound rocket motor cases, approximately 26.25 inches long by 25.50 inches diameter, utilizing graphite fibers. The process utilized prepreg tape which consists of Fortafil 4-R fibers in the E-759 epoxy resin matrix. This fabrication effect demonstrated an ability to fabricate high quality graphite/epoxy rocket motor cases in the 26.25 inch by 25.50 inch size range.

Doped Aluminum Gallium Arsenide (AlGaAs)/Gallium Arsenide (GaAs) Photoconductive Semiconductor Switch (PCSS) Fabrication

DTIC Science & Technology

2016-09-27

contact regions and epitaxial capping layer are fabricated to investigate the advantages of both approaches. Devices were fabricated with various... Contacts 7 2.5 Packaging 11 3. Conclusions 12 4. References 13 Appendix. Detailed Fabrication Process 15 List of Symbols, Abbreviations, and...regions in violet (overlaying previous patterns) .......7 Fig. 6 Mask 4: intrinsic device contact window regions in orange (overlaying previous

Physical and Thermal Comfort Properties of Viscose Fabrics made from Vortex and Ring Spun Yarns

NASA Astrophysics Data System (ADS)

Thilagavathi, G.; Muthukumar, N.; Kumar, V. Kiran; Sadasivam, Sanjay; Sidharth, P. Mithun; Nikhil Jain, G.

2017-06-01

Viscose fiber is frequently preferred for various types of inner and outer knitwear products for its comfort and visual characteristics. In this study, the physical and thermal comfort properties of viscose fabrics made from ring and vortex yarns have been studied to explore the impact of spinning process on fabric properties. 100% viscose fibers were spun into yarns by ring and vortex spinning and the developed yarns were converted to single jersey fabrics. The results indicated that fabrics made from vortex spun yarns had better pilling resistance over that of those from ring spun yarns. There was no significant difference between bursting strength values of vortex and ring spun yarn fabrics. Fabrics made from ring yarn had better dimensional stability compared to fabrics made from vortex yarn. The air permeability and water vapour permeability of vortex yarn fabrics were higher than ring spun yarn fabrics. The vortex yarn fabrics had better thermal comfort properties compared to ring yarn fabrics.

Regenerated silk materials for functionalized silk orthopedic devices by mimicking natural processing.

PubMed

Li, Chunmei; Hotz, Blake; Ling, Shengjie; Guo, Jin; Haas, Dylan S; Marelli, Benedetto; Omenetto, Fiorenzo; Lin, Samuel J; Kaplan, David L

2016-12-01

Silk fibers spun by silkworms and spiders exhibit exceptional mechanical properties with a unique combination of strength, extensibility and toughness. In contrast, the mechanical properties of regenerated silk materials can be tuned through control of the fabrication process. Here we introduce a biomimetic, all-aqueous process, to obtain bulk regenerated silk-based materials for the fabrication of functionalized orthopedic devices. The silk materials generated in the process replicate the nano-scale structure of natural silk fibers and possess excellent mechanical properties. The biomimetic materials demonstrate excellent machinability, providing a path towards the fabrication of a new family of resorbable orthopedic devices where organic solvents are avoided, thus allowing functionalization with bioactive molecules to promote bone remodeling and integration. Copyright © 2016 Elsevier Ltd. All rights reserved.

Advanced ACTPol Multichroic Polarimeter Array Fabrication Process for 150 mm Wafers

NASA Astrophysics Data System (ADS)

Duff, S. M.; Austermann, J.; Beall, J. A.; Becker, D.; Datta, R.; Gallardo, P. A.; Henderson, S. W.; Hilton, G. C.; Ho, S. P.; Hubmayr, J.; Koopman, B. J.; Li, D.; McMahon, J.; Nati, F.; Niemack, M. D.; Pappas, C. G.; Salatino, M.; Schmitt, B. L.; Simon, S. M.; Staggs, S. T.; Stevens, J. R.; Van Lanen, J.; Vavagiakis, E. M.; Ward, J. T.; Wollack, E. J.

2016-08-01

Advanced ACTPol (AdvACT) is a third-generation cosmic microwave background receiver to be deployed in 2016 on the Atacama Cosmology Telescope (ACT). Spanning five frequency bands from 25 to 280 GHz and having just over 5600 transition-edge sensor (TES) bolometers, this receiver will exhibit increased sensitivity and mapping speed compared to previously fielded ACT instruments. This paper presents the fabrication processes developed by NIST to scale to large arrays of feedhorn-coupled multichroic AlMn-based TES polarimeters on 150-mm diameter wafers. In addition to describing the streamlined fabrication process which enables high yields of densely packed detectors across larger wafers, we report the details of process improvements for sensor (AlMn) and insulator (SiN_x) materials and microwave structures, and the resulting performance improvements.

Weld-brazing - a new joining process. [combination resistance spot welding and brazing of titanium alloys

NASA Technical Reports Server (NTRS)

Bales, T. T.; Royster, D. M.; Arnold, W. E., Jr.

1972-01-01

A joining process designated weld brazing which combines resistance spot welding and brazing has been developed. Resistance spot welding is used to position and align the parts as well as to establish a suitable faying surface gap for brazing. Fabrication is then completed by capillary flow of the braze alloy into the joint. The process has been used successfully to fabricate Ti-6Al-4V titanium alloy joints using 3003 aluminum braze alloy. Test results obtained on single overlap and hat-stiffened structural specimens show that weld brazed joints are superior in tensile shear, stress rupture, fatigue, and buckling than joint fabricated by spotwelding or brazing. Another attractive feature of the process is that the brazed joints is hermetically sealed by the braze material.

Ecosystem protection by effluent bioremediation: silver nanoparticles impregnation in a textile fabrics process

NASA Astrophysics Data System (ADS)

Durán, Nelson; Marcato, Priscyla D.; Alves, Oswaldo L.; Da Silva, João P. S.; De Souza, Gabriel I. H.; Rodrigues, Flávio A.; Esposito, Elisa

2010-01-01

This work studied a bioremediation process of silver nanoparticles with the bacterium Chromobacterium violaceum. These nanoparticles were obtained from several washes of cotton fabrics impregnated with silver nanoparticles produced by the fungus Fusarium oxysporum. The optimized growth of C. violaceum for silver nanoparticles bioremediation was obtained. The effluents of wash process of the cotton fabric were efficiently treated with C. violaceum. This treatment was based on biosorption which was very efficient for the elimination of silver nanoparticles remaining in the wash water. The bacteria after biosorption were morphologically transformed, but the normal morphology after a new culture was completely restored. The process also allowed the recovery of silver material that was leached into the effluent for a reutilization avoiding any effect to the eco-environment.

Advanced ACTPol Multichroic Polarimeter Array Fabrication Process for 150 mm Wafers

NASA Technical Reports Server (NTRS)

Duff, S. M.; Austermann, J.; Beall, J. A.; Becker, D.; Datta, R.; Gallardo, P. A.; Henderson, S. W.; Hilton, G. C.; Ho, S. P.; Hubmayr, J.;

Space Construction Automated Fabrication Experiment Definition Study (SCAFEDS). Volume 1: Executive summary

NASA Technical Reports Server (NTRS)

1978-01-01

The techniques, processes, and equipment required for automatic fabrication and assembly of structural elements in space using the space shuttle as a launch vehicle and construction base were investigated. Additional construction/systems/operational techniques, processes, and equipment which can be developed/demonstrated in the same program to provide further risk reduction benefits to future large space systems were included. Results in the areas of structure/materials, fabrication systems (beam builder, assembly jig, and avionics/controls), mission integration, and programmatics are summarized. Conclusions and recommendations are given.

[An experimental research on the fabrication of the fused porcelain to CAD/CAM molar crown].

PubMed

Dai, Ning; Zhou, Yongyao; Liao, Wenhe; Yu, Qing; An, Tao; Jiao, Yiqun

2007-02-01

This paper introduced the fabrication process of the fused porcelain to molar crown with CAD/CAM technology. Firstly, preparation teeth data was retrieved by the 3D-optical measuring system. Then, we have reconstructed the inner surface designed the outer surface shape with the computer aided design software. Finally, the mini high-speed NC milling machine was used to produce the fused porcelain to CAD/CAM molar crown. The result has proved that the fabrication process is reliable and efficient. The dental restoration quality is steady and precise.

Solidification and solid-state transformation sciences in metals additive manufacturing

DOE PAGES

Kirka, Michael M.; Nandwana, Peeyush; Lee, Yousub; ...

2017-02-11

Additive manufacturing (AM) of metals is rapidly emerging as an established manufacturing process for metal components. Unlike traditional metals fabrication processes, metals fabricated via AM undergo localized thermal cycles during fabrication. As a result, AM presents the opportunity to control the liquid-solid phase transformation, i.e. material texture. But, thermal cycling presents challenges from the standpoint of solid-solid phase transformations. We will discuss the opportunities and challenges in metals AM in the context of texture control and associated solid-solid phase transformations in Ti-6Al-4V and Inconel 718.

Magnesium doping of boron nitride nanotubes

DOEpatents

Legg, Robert; Jordan, Kevin

2015-06-16

A method to fabricate boron nitride nanotubes incorporating magnesium diboride in their structure. In a first embodiment, magnesium wire is introduced into a reaction feed bundle during a BNNT fabrication process. In a second embodiment, magnesium in powder form is mixed into a nitrogen gas flow during the BNNT fabrication process. MgB.sub.2 yarn may be used for superconducting applications and, in that capacity, has considerably less susceptibility to stress and has considerably better thermal conductivity than these conventional materials when compared to both conventional low and high temperature superconducting materials.

In Situ Electrochemical Deposition of Microscopic Wires

NASA Technical Reports Server (NTRS)

Yun, Minhee; Myung, Nosang; Vasquez, Richard

2005-01-01

A method of fabrication of wires having micron and submicron dimensions is built around electrochemical deposition of the wires in their final positions between electrodes in integrated circuits or other devices in which the wires are to be used. Heretofore, nanowires have been fabricated by a variety of techniques characterized by low degrees of controllability and low throughput rates, and it has been necessary to align and electrically connect the wires in their final positions by use of sophisticated equipment in expensive and tedious post-growth assembly processes. The present method is more economical, offers higher yields, enables control of wire widths, and eliminates the need for post-growth assembly. The wires fabricated by this method could be used as simple electrical conductors or as transducers in sensors. Depending upon electrodeposition conditions and the compositions of the electroplating solutions in specific applications, the wires could be made of metals, alloys, metal oxides, semiconductors, or electrically conductive polymers. In this method, one uses fabrication processes that are standard in the semiconductor industry. These include cleaning, dry etching, low-pressure chemical vapor deposition, lithography, dielectric deposition, electron-beam lithography, and metallization processes as well as the electrochemical deposition process used to form the wires. In a typical case of fabrication of a circuit that includes electrodes between which microscopic wires are to be formed on a silicon substrate, the fabrication processes follow a standard sequence until just before the fabrication of the microscopic wires. Then, by use of a thermal SiO-deposition technique, the electrodes and the substrate surface areas in the gaps between them are covered with SiO. Next, the SiO is electron-beam patterned, then reactive-ion etched to form channels having specified widths (typically about 1 m or less) that define the widths of the wires to be formed. Drops of an electroplating solution are placed on the substrate in the regions containing the channels thus formed, then the wires are electrodeposited from the solution onto the exposed portions of the electrodes and into the channels. The electrodeposition is a room-temperature, atmospheric-pressure process. The figure shows an example of palladium wires that were electrodeposited into 1-mm-wide channels between gold electrodes.

cm-scale variations of crystal orientation fabric in cold Alpine ice core from Colle Gnifetti

NASA Astrophysics Data System (ADS)

Kerch, Johanna; Weikusat, Ilka; Eisen, Olaf; Wagenbach, Dietmar; Erhardt, Tobias

2015-04-01

Analysis of the microstructural parameters of ice has been an important part of ice core analyses so far mainly in polar cores in order to obtain information about physical processes (e.g. deformation, recrystallisation) on the micro- and macro-scale within an ice body. More recently the influence of impurities and climatic conditions during snow accumulation on these processes has come into focus. A deeper understanding of how palaeoclimate proxies interact with physical properties of the ice matrix bears relevance for palaeoclimatic interpretations, improved geophysical measurement techniques and the furthering of ice dynamical modeling. Variations in microstructural parameters e.g. crystal orientation fabric or grain size can be observed on a scale of hundreds and tens of metres but also on a centimetre scale. The underlying processes are not necessarily the same on all scales. Especially for the short-scale variations many questions remain unanswered. We present results from a study that aims to investigate following hypotheses: 1. Variations in grain size and fabric, i.e. strong changes of the orientation of ice crystals with respect to the vertical, occur on a centimetre scale and can be observed in all depths of an ice core. 2. Palaeoclimate proxies like dust and impurities have an impact on the microstructural processes and thus are inducing the observed short-scale variations in grain size and fabric. 3. The interaction of proxies with the ice matrix leads to depth intervals that show correlating behaviour as well as ranges with anticorrelation between microstructural parameters and palaeoclimatic proxies. The respective processes need to be identified. Fabric Analyser measurements were conducted on more than 80 samples (total of 8 m) from different depth ranges of a cold Alpine ice core (72 m length) drilled in 2013 at Colle Gnifetti, Switzerland/Italy. Results were obtained by automatic image processing, providing estimates for grain size distributions and crystal orientation fabric, and comparison with data from continuous flow analysis of chemical impurities. A microstructural characterisation of the analysed core is presented with emphasis on the observed variations in crystal orientation fabric. The relevance of these results for palaeoclimate reconstruction and geophysical applications in ice are discussed.

Electrochemical formation of field emitters

DOEpatents

Bernhardt, A.F.

1999-03-16

Electrochemical formation of field emitters, particularly useful in the fabrication of flat panel displays is disclosed. The fabrication involves field emitting points in a gated field emitter structure. Metal field emitters are formed by electroplating and the shape of the formed emitter is controlled by the potential imposed on the gate as well as on a separate counter electrode. This allows sharp emitters to be formed in a more inexpensive and manufacturable process than vacuum deposition processes used at present. The fabrication process involves etching of the gate metal and the dielectric layer down to the resistor layer, and then electroplating the etched area and forming an electroplated emitter point in the etched area. 12 figs.

Fabrication of diamond shells

DOEpatents

Hamza, Alex V.; Biener, Juergen; Wild, Christoph; Woerner, Eckhard

2016-11-01

A novel method for fabricating diamond shells is introduced. The fabrication of such shells is a multi-step process, which involves diamond chemical vapor deposition on predetermined mandrels followed by polishing, microfabrication of holes, and removal of the mandrel by an etch process. The resultant shells of the present invention can be configured with a surface roughness at the nanometer level (e.g., on the order of down to about 10 nm RMS) on a mm length scale, and exhibit excellent hardness/strength, and good transparency in the both the infra-red and visible. Specifically, a novel process is disclosed herein, which allows coating of spherical substrates with optical-quality diamond films or nanocrystalline diamond films.

Rapid prototype fabrication processes for high-performance thrust cells

NASA Technical Reports Server (NTRS)

Hunt, K.; Chwiedor, T.; Diab, J.; Williams, R.

1994-01-01

The Thrust Cell Technologies Program (Air Force Phillips Laboratory Contract No. F04611-92-C-0050) is currently being performed by Rocketdyne to demonstrate advanced materials and fabrication technologies which can be utilized to produce low-cost, high-performance thrust cells for launch and space transportation rocket engines. Under Phase 2 of the Thrust Cell Technologies Program (TCTP), rapid prototyping and investment casting techniques are being employed to fabricate a 12,000-lbf thrust class combustion chamber for delivery and hot-fire testing at Phillips Lab. The integrated process of investment casting directly from rapid prototype patterns dramatically reduces design-to-delivery cycle time, and greatly enhances design flexibility over conventionally processed cast or machined parts.

Fabrication of boron sputter targets

DOEpatents

Makowiecki, Daniel M.; McKernan, Mark A.

1995-01-01

A process for fabricating high density boron sputtering targets with sufficient mechanical strength to function reliably at typical magnetron sputtering power densities and at normal process parameters. The process involves the fabrication of a high density boron monolithe by hot isostatically compacting high purity (99.9%) boron powder, machining the boron monolithe into the final dimensions, and brazing the finished boron piece to a matching boron carbide (B.sub.4 C) piece, by placing aluminum foil there between and applying pressure and heat in a vacuum. An alternative is the application of aluminum metallization to the back of the boron monolithe by vacuum deposition. Also, a titanium based vacuum braze alloy can be used in place of the aluminum foil.

Trapped rubber processing for advanced composites

NASA Technical Reports Server (NTRS)

Marra, P. J.

1976-01-01

Trapped rubber processing is a molding technique for composites in which precast silicone rubber is placed within a closed cavity where it thermally expands against the composite's surface supported by the vessel walls. The method has been applied by the Douglas Aircraft Company, under contract to NASA-Langley, to the design and fabrication of 10 DC-10 graphite/epoxy upper aft rudder assemblies. A three-bay development tool form mold die has been designed and manufactured, and tooling parameters have been established. Fabrication procedures include graphite layup, assembly of details in the tool, and a cure cycle. The technique has made it possible for the cocured fabrication of complex primary box structures otherwise impracticable via standard composite material processes.

Green piezoelectric for autonomous smart textile

NASA Astrophysics Data System (ADS)

Lemaire, E.; Borsa, C. J.; Briand, D.

2015-12-01

In this work, the fabrication of Rochelle salt based piezoelectric textiles are shown. Structures composed of fibers and Rochelle salt are easily produced using green processes. Both manufacturing and the material itself are really efficient in terms of environmental impact, considering the fabrication processes and the material resources involved. Additionally Rochelle salt is biocompatible. In this green paradigm, active sensing or actuating textiles are developed. Thus processing method and piezoelectric properties have been studied: (1) pure crystals are used as acoustic actuator, (2) fabrication of the textile-based composite is detailed, (3) converse effective d33 is evaluated and compared to lead zirconate titanate ceramic. The utility of textile-based piezoelectric merits its use in a wide array of applications.

The Effect of Surfactant Content over Cu-Ni Coatings Electroplated by the sc-CO₂ Technique.

PubMed

Chuang, Ho-Chiao; Sánchez, Jorge; Cheng, Hsiang-Yun

2017-04-19

Co-plating of Cu-Ni coatings by supercritical CO₂ (sc-CO₂) and conventional electroplating processes was studied in this work. 1,4-butynediol was chosen as the surfactant and the effects of adjusting the surfactant content were described. Although the sc-CO₂ process displayed lower current efficiency, it effectively removed excess hydrogen that causes defects on the coating surface, refined grain size, reduced surface roughness, and increased electrochemical resistance. Surface roughness of coatings fabricated by the sc-CO₂ process was reduced by an average of 10%, and a maximum of 55%, compared to conventional process at different fabrication parameters. Cu-Ni coatings produced by the sc-CO₂ process displayed increased corrosion potential of ~0.05 V over Cu-Ni coatings produced by the conventional process, and 0.175 V over pure Cu coatings produced by the conventional process. For coatings ~10 µm thick, internal stress developed from the sc-CO₂ process were ~20 MPa lower than conventional process. Finally, the preferred crystal orientation of the fabricated coatings remained in the (111) direction regardless of the process used or surfactant content.

Plastic masters-rigid templates for soft lithography.

PubMed

Desai, Salil P; Freeman, Dennis M; Voldman, Joel

2009-06-07

We demonstrate a simple process for the fabrication of rigid plastic master molds for soft lithography directly from (poly)dimethysiloxane devices. Plastics masters (PMs) provide a cost-effective alternative to silicon-based masters and can be easily replicated without the need for cleanroom facilities. We have successfully demonstrated the use of plastics micromolding to generate both single and dual-layer plastic structures, and have characterized the fidelity of the molding process. Using the PM fabrication technique, world-to-chip connections can be integrated directly into the master enabling devices with robust, well-aligned fluidic ports directly after molding. PMs provide an easy technique for the fabrication of microfluidic devices and a simple route for the scaling-up of fabrication of robust masters for soft lithography.

Microstructure and inclusion of Ti-6Al-4V fabricated by selective laser melting

NASA Astrophysics Data System (ADS)

Huang, Qianli; Hu, Ningmin; Yang, Xing; Zhang, Ranran; Feng, Qingling

2016-12-01

Selective laser melting (SLM) was used in fabricating the dense part from pre-alloyed Ti-6Al-4V powder. The microstructural evolution and inclusion formation of as-fabricated part were characterized in depth. The microstructure was characterized by features of columnar prior β grains and acicular martensite α'. High density defects such as dislocations and twins can be produced in SLM process. Investigations on the inclusions find out that hard alpha inclusion, amorphous CaO and microcrystalline Al2O3 are three main inclusions formed in SLM. The inclusions formed at some specific sites on melt pool surface. The microstructural evolution and inclusion formation of as-fabricated material are closely related to the SLM process.

Relationships between Lead Halide Perovskite Thin-Film Fabrication, Morphology, and Performance in Solar Cells.

PubMed

Sharenko, Alexander; Toney, Michael F

2016-01-20

Solution-processed lead halide perovskite thin-film solar cells have achieved power conversion efficiencies comparable to those obtained with several commercial photovoltaic technologies in a remarkably short period of time. This rapid rise in device efficiency is largely the result of the development of fabrication protocols capable of producing continuous, smooth perovskite films with micrometer-sized grains. Further developments in film fabrication and morphological control are necessary, however, in order for perovskite solar cells to reliably and reproducibly approach their thermodynamic efficiency limit. This Perspective discusses the fabrication of lead halide perovskite thin films, while highlighting the processing-property-performance relationships that have emerged from the literature, and from this knowledge, suggests future research directions.

Fabrication of a Miniaturized ZnO Nanowire Accelerometer and Its Performance Tests

PubMed Central

Kim, Hyun Chan; Song, Sangho; Kim, Jaehwan

2016-01-01

This paper reports a miniaturized piezoelectric accelerometer suitable for a small haptic actuator array. The accelerometer is made with zinc oxide (ZnO) nanowire (NW) grown on a copper wafer by a hydrothermal process. The size of the accelerometer is 1.5 × 1.5 mm2, thus fitting the 1.8 × 1.8 mm2 haptic actuator array cell. The detailed fabrication process of the miniaturized accelerometer is illustrated. Performance evaluation of the fabricated accelerometer is conducted by comparing it with a commercial piezoelectric accelerometer. The output current of the fabricated accelerometer increases linearly with the acceleration. The miniaturized ZnO NW accelerometer is feasible for acceleration measurement of small and lightweight devices. PMID:27649184

Technology of combined chemical-mechanical fabrication of durable coatings

NASA Astrophysics Data System (ADS)

Smolentsev, V. P.; Ivanov, V. V.; Portnykh, A. I.

2018-03-01

The article presents the scientific fundamentals of methodology for calculating the modes and structuring the technological processes of combined chemical-mechanical fabrication of durable coatings. It is shown that they are based on classical patterns, describing the processes of simultaneous chemical and mechanical impact. The paper demonstrates the possibility of structuring a technological process, taking into account the systematic approach to impact management and strengthening the reciprocal positive influence of each impact upon the combined process. The combined processes have been planned for fabricating the model types of chemical-mechanical coatings of durable products in machine construction. The planning methodology is underpinned by a scientific hypothesis of a single source of impact management through energy potential of process components themselves, or by means of external energy supply through mechanical impact. The control of it is fairly thoroughly studied in the case of pulsed external strikes of hard pellets, similar to processes of vibroimpact hardening, thoroughly studied and mastered in many scientific schools of Russia.

Scalable Manufacturing of Plasmonic Nanodisk Dimers and Cusp Nanostructures using Salting-out Quenching Method and Colloidal Lithography

PubMed Central

Juluri, Bala Krishna; Chaturvedi, Neetu; Hao, Qingzhen; Lu, Mengqian; Velegol, Darrell; Jensen, Lasse; Huang, Tony Jun

2014-01-01

Localization of large electric fields in plasmonic nanostructures enables various processes such as single molecule detection, higher harmonic light generation, and control of molecular fluorescence and absorption. High-throughput, simple nanofabrication techniques are essential for implementing plasmonic nanostructures with large electric fields for practical applications. In this article we demonstrate a scalable, rapid, and inexpensive fabrication method based on the salting-out quenching technique and colloidal lithography for the fabrication of two types of nanostructures with large electric field: nanodisk dimers and cusp nanostructures. Our technique relies on fabricating polystyrene doublets from single beads by controlled aggregation and later using them as soft masks to fabricate metal nanodisk dimers and nanocusp structures. Both of these structures have a well-defined geometry for the localization of large electric fields comparable to structures fabricated by conventional nanofabrication techniques. We also show that various parameters in the fabrication process can be adjusted to tune the geometry of the final structures and control their plasmonic properties. With advantages in throughput, cost, and geometric tunability, our fabrication method can be valuable in many applications that require plasmonic nanostructures with large electric fields. PMID:21692473

High performance printed oxide field-effect transistors processed using photonic curing.

PubMed

Garlapati, Suresh Kumar; Marques, Gabriel Cadilha; Gebauer, Julia Susanne; Dehm, Simone; Bruns, Michael; Winterer, Markus; Tahoori, Mehdi Baradaran; Aghassi-Hagmann, Jasmin; Hahn, Horst; Dasgupta, Subho

2018-06-08

Oxide semiconductors are highly promising candidates for the most awaited, next-generation electronics, namely, printed electronics. As a fabrication route for the solution-processed/printed oxide semiconductors, photonic curing is becoming increasingly popular, as compared to the conventional thermal curing method; the former offers numerous advantages over the latter, such as low process temperatures and short exposure time and thereby, high throughput compatibility. Here, using dissimilar photonic curing concepts (UV-visible light and UV-laser), we demonstrate facile fabrication of high performance In 2 O 3 field-effect transistors (FETs). Beside the processing related issues (temperature, time etc.), the other known limitation of oxide electronics is the lack of high performance p-type semiconductors, which can be bypassed using unipolar logics from high mobility n-type semiconductors alone. Interestingly, here we have found that our chosen distinct photonic curing methods can offer a large variation in threshold voltage, when they are fabricated from the same precursor ink. Consequently, both depletion and enhancement-mode devices have been achieved which can be used as the pull-up and pull-down transistors in unipolar inverters. The present device fabrication recipe demonstrates fast processing of low operation voltage, high performance FETs with large threshold voltage tunability.

Fracture Toughness of Carbon Fiber Composites Containing Various Fiber Sizings and a Puncture Self-Healing Thermoplastic Matrix

NASA Technical Reports Server (NTRS)

Cano, Roberto J.; Grimsley, Brian W.; Ratcliffe, James G.; Gordon, Keith L.; Smith, Joseph G.; Siochi, Emilie J.

2015-01-01

Ongoing efforts at NASA Langley Research Center (LaRC) have resulted in the identification of several commercially available thermoplastic resin systems which self-heal after ballistic impact and through penetration. One of these resins, polybutylene graft copolymer (PBg), was selected as a matrix for processing with unsized carbon fibers to fabricate reinforced composites for further evaluation. During process development, data from thermo-physical analyses was utilized to determine a processing cycle to fabricate laminate panels, which were analyzed by photo microscopy and acid digestion. The process cycle was further optimized based on these results to fabricate panels for mechanical property characterization. The results of the processing development effort of this composite material, as well as the results of the mechanical property characterization, indicated that bonding between the fiber and PBg was not adequate. Therefore, three sizings were investigated in this work to assess their potential to improve fiber/matrix bonding compared to previously tested unsized IM7 fiber. Unidirectional prepreg was made at NASA LaRC from three sized carbon fibers and utilized to fabricate test coupons that were tested in double cantilever beam configurations to determine GIc fracture toughness.

Process development for high-resolution 3D-printing of bioresorbable vascular stents

NASA Astrophysics Data System (ADS)

Ware, Henry Oliver T.; Farsheed, Adam C.; van Lith, Robert; Baker, Evan; Ameer, Guillermo; Sun, Cheng

2017-02-01

The recent development of "continuous projection microstereolithography" also known as CLIP technology has successfully alleviated the main obstacles surrounding 3D printing technologies: production speed and part quality. Following the same working principle, we further developed the μCLIP process to address the needs for high-resolution 3D printing of biomedical devices with micron-scale precision. Compared to standard stereolithography (SLA) process, μCLIP fabrication can reduce fabrication time from several hours to as little as a few minutes. μCLIP can also produce better surface finish and more uniform mechanical properties than conventional SLA, as each individual "fabrication layer" continuously polymerizes into the subsequent layer. In this study, we report the process development in manufacturing high-resolution bioresorbable stents using our own μCLIP system. The bioresorbable photopolymerizable biomaterial (B-ink) used in this study is methacrylated poly(1, 12 dodecamethylene citrate) (mPDC). Through optimization of our μCLIP process and concentration of B-ink components, we have created a customizable bioresorbable stent with similar mechanical properties exhibited by nitinol stents. Upon optimization, fabricating a 2 cm tall vascular stent that comprises 4000 layers was accomplished in 26.5 minutes.

Direct ink writing of 3D conductive polyaniline structures and rheological modelling

NASA Astrophysics Data System (ADS)

Holness, F. Benjamin; Price, Aaron D.

2018-01-01

The intractable nature of conjugated polymers (CP) leads to practical limitations in the fabrication of CP-based transducers having complex three-dimensional geometries. Conventional CP device fabrication processes have focused primarily on thin-film deposition techniques; this study explores novel additive manufacturing processes specifically developed for CP with the ultimate goal of increasing the functionality of CP sensors and actuators. Herein we employ automated polymer paste extrusion processes for the direct ink writing of 3D conductive polyaniline (PANI) structures. Realization of these structures was enabled through a modified fused filament fabrication delta robot equipped with an integrated polymer paste extruder to fabricate high-resolution 3D conductive PANI structures. The required processability of PANI was achieved by means of a counterion-induced thermal doping method. The effect of thermal doping on the PANI-DBSA paste by means of a constitutive relationship to describe the paste flow as a function of the thermal doping time is explored. This relationship is incorporated within a flow model to predict the extruded track width as a function of various process parameters including: print speed, gauge pressure, nozzle diameter, and pre-extrusion thermal doping time.

Atomically Traceable Nanostructure Fabrication

PubMed Central

Ballard, Josh B.; Dick, Don D.; McDonnell, Stephen J.; Bischof, Maia; Fu, Joseph; Owen, James H. G.; Owen, William R.; Alexander, Justin D.; Jaeger, David L.; Namboodiri, Pradeep; Fuchs, Ehud; Chabal, Yves J.; Wallace, Robert M.; Reidy, Richard; Silver, Richard M.; Randall, John N.; Von Ehr, James

2015-01-01

Reducing the scale of etched nanostructures below the 10 nm range eventually will require an atomic scale understanding of the entire fabrication process being used in order to maintain exquisite control over both feature size and feature density. Here, we demonstrate a method for tracking atomically resolved and controlled structures from initial template definition through final nanostructure metrology, opening up a pathway for top-down atomic control over nanofabrication. Hydrogen depassivation lithography is the first step of the nanoscale fabrication process followed by selective atomic layer deposition of up to 2.8 nm of titania to make a nanoscale etch mask. Contrast with the background is shown, indicating different mechanisms for growth on the desired patterns and on the H passivated background. The patterns are then transferred into the bulk using reactive ion etching to form 20 nm tall nanostructures with linewidths down to ~6 nm. To illustrate the limitations of this process, arrays of holes and lines are fabricated. The various nanofabrication process steps are performed at disparate locations, so process integration is discussed. Related issues are discussed including using fiducial marks for finding nanostructures on a macroscopic sample and protecting the chemically reactive patterned Si(100)-H surface against degradation due to atmospheric exposure. PMID:26274555

Atomically Traceable Nanostructure Fabrication.

PubMed

Ballard, Josh B; Dick, Don D; McDonnell, Stephen J; Bischof, Maia; Fu, Joseph; Owen, James H G; Owen, William R; Alexander, Justin D; Jaeger, David L; Namboodiri, Pradeep; Fuchs, Ehud; Chabal, Yves J; Wallace, Robert M; Reidy, Richard; Silver, Richard M; Randall, John N; Von Ehr, James

2015-07-17

Reducing the scale of etched nanostructures below the 10 nm range eventually will require an atomic scale understanding of the entire fabrication process being used in order to maintain exquisite control over both feature size and feature density. Here, we demonstrate a method for tracking atomically resolved and controlled structures from initial template definition through final nanostructure metrology, opening up a pathway for top-down atomic control over nanofabrication. Hydrogen depassivation lithography is the first step of the nanoscale fabrication process followed by selective atomic layer deposition of up to 2.8 nm of titania to make a nanoscale etch mask. Contrast with the background is shown, indicating different mechanisms for growth on the desired patterns and on the H passivated background. The patterns are then transferred into the bulk using reactive ion etching to form 20 nm tall nanostructures with linewidths down to ~6 nm. To illustrate the limitations of this process, arrays of holes and lines are fabricated. The various nanofabrication process steps are performed at disparate locations, so process integration is discussed. Related issues are discussed including using fiducial marks for finding nanostructures on a macroscopic sample and protecting the chemically reactive patterned Si(100)-H surface against degradation due to atmospheric exposure.

Room-Temperature and Solution-Processable Cu-Doped Nickel Oxide Nanoparticles for Efficient Hole-Transport Layers of Flexible Large-Area Perovskite Solar Cells.

PubMed

He, Qiqi; Yao, Kai; Wang, Xiaofeng; Xia, Xuefeng; Leng, Shifeng; Li, Fan

2017-12-06

Flexible perovskite solar cells (PSCs) using plastic substrates have become one of the most attractive points in the field of thin-film solar cells. Low-temperature and solution-processable nanoparticles (NPs) enable the fabrication of semiconductor thin films in a simple and low-cost approach to function as charge-selective layers in flexible PSCs. Here, we synthesized phase-pure p-type Cu-doped NiO x NPs with good electrical properties, which can be processed to smooth, pinhole-free, and efficient hole transport layers (HTLs) with large-area uniformity over a wide range of film thickness using a room-temperature solution-processing technique. Such a high-quality inorganic HTL allows for the fabrication of flexible PSCs with an active area >1 cm 2 , which have a power conversion efficiency over 15.01% without hysteresis. Moreover, the Cu/NiO x NP-based flexible devices also demonstrate excellent air stability and mechanical stability compared to their counterpart fabricated on the pristine NiO x films. This work will contribute to the evolution of upscaling flexible PSCs with a simple fabrication process and high device performances.

Processing of high performance (LRE)-Ba Cu O large, single-grain bulk superconductors in air

NASA Astrophysics Data System (ADS)

Hari Babu, N.; Iida, K.; Shi, Y.; Cardwell, D. A.

2006-10-01

We report the fabrication of large (LRE)BCO single-grains with improved superconducting properties for LRE = Nd, Sm and Gd using a practical process via both conventional top seeded melt growth (TSMG) and seeded infiltration-growth (SIG). This process uses a new generic seed crystal that promotes heterogeneous grain nucleation in the required orientation and suppresses the formation of solid solution in a controlled manner within individual grains by the addition of excess BaO2 to the precursor powder. The spatial distribution of the superconducting properties of LRE bulk superconductors as a function of BaO2 addition for large (LRE)BCO grains fabricated in air by TSMG and SIG for LRE = Gd, Sm and Nd are compared. The optimum BaO2 content required to fabricate single-grain (LRE)BCO with high and homogeneous Tc is determined from these experiments for each LRE system. The irreversibility fields of (LRE)BCO bulk superconductors processed in air are as high as those processed in reduced PO2. Critical current densities in excess of 105 A/cm2 at 77 K and higher trapped fields have been achieved in optimized (LRE)BCO superconductors fabricated in air for the first time.

Effect of fabrication processes on mechanical properties of glass fiber reinforced polymer composites for 49 meter (160 foot) recreational yachts

NASA Astrophysics Data System (ADS)

Kim, Dave (dea-wook); Hennigan, Daniel John; Beavers, Kevin Daniel

2010-03-01

Polymer composite materialsoffer high strength and stiffness to weight ratio, corrosion resistance, and total life cost reductions that appeal to the marine industry. The advantages of composite construction have led to their incorporation in U.S. yacht hull structures over 46 meters (150 feet) in length. In order to construct even larger hull structures, higher quality composites with a lower cost production techniques need to be developed. In this study, the effect of composite hull fabrication processes on mechanical properties of glass fiber reinforced plastic(GFRP) composites is presented. Fabrication techniques used in this study are hand lay-up (HL), vacuum infusion (VI), and hybrid (HL+VI) processes. Mechanical property testing includes: tensile, compressive, and ignition loss sample analysis. Results demonstrate that the vacuum pressure implemented during composite fabrication has an effect on mechanical properties. The VI processed GFRP yields improved mechanical properties in tension/compression strengths and tensile modulus. The hybrid GFRP composites, however, failed in a sequential manor, due to dissimilar failure modes in the HL and VI processed sides. Fractography analysis was conducted to validate the mechanical property testing results

The effect of processing on the mechanical properties of self-reinforced composites

NASA Astrophysics Data System (ADS)

Hassani, Farzaneh; Martin, Peter J.; Falzon, Brian G.

2018-05-01

Hot-compaction is one of the most common manufacturing methods for creating recyclable all thermoplastic composites. The current work investigates the compaction of highly oriented self-reinforced fabrics with three processing methods to study the effect of pressure and temperature in the tensile mechanical properties of the consolidated laminates. Hot-press, calender roller and vacuum bag technique were adopted to consolidate bi-component polypropylene woven fabrics in a range of pressures and compaction temperatures. Hot-pressed samples exhibited the highest quality of compaction. The modulus of the hot-pressed samples increased with compaction temperature initially due to the improved interlayer bonding and decreased after a maximum at 150°C because of partial melting of the reinforcement phase. The calender roller technique exhibited to have smaller processing temperature window as the pressure is only applied for a short time and the fabrics start to shrink with increasing the processing temperature. The need for constraining the fabrics through the process is therefore found to be paramount. The Vacuum bag results showed this technique to be the least efficient method because of the low compaction pressure. Microscopic images and void content measurement of the consolidated samples further validate the results from tensile testing.

High performance printed oxide field-effect transistors processed using photonic curing

NASA Astrophysics Data System (ADS)

Garlapati, Suresh Kumar; Cadilha Marques, Gabriel; Gebauer, Julia Susanne; Dehm, Simone; Bruns, Michael; Winterer, Markus; Baradaran Tahoori, Mehdi; Aghassi-Hagmann, Jasmin; Hahn, Horst; Dasgupta, Subho

2018-06-01

Oxide semiconductors are highly promising candidates for the most awaited, next-generation electronics, namely, printed electronics. As a fabrication route for the solution-processed/printed oxide semiconductors, photonic curing is becoming increasingly popular, as compared to the conventional thermal curing method; the former offers numerous advantages over the latter, such as low process temperatures and short exposure time and thereby, high throughput compatibility. Here, using dissimilar photonic curing concepts (UV–visible light and UV-laser), we demonstrate facile fabrication of high performance In2O3 field-effect transistors (FETs). Beside the processing related issues (temperature, time etc.), the other known limitation of oxide electronics is the lack of high performance p-type semiconductors, which can be bypassed using unipolar logics from high mobility n-type semiconductors alone. Interestingly, here we have found that our chosen distinct photonic curing methods can offer a large variation in threshold voltage, when they are fabricated from the same precursor ink. Consequently, both depletion and enhancement-mode devices have been achieved which can be used as the pull-up and pull-down transistors in unipolar inverters. The present device fabrication recipe demonstrates fast processing of low operation voltage, high performance FETs with large threshold voltage tunability.

Process for manufacturing multilayer capacitors

DOEpatents

Lauf, Robert J.; Holcombe, Cressie E.; Dykes, Norman L.

1996-01-01

The invention is directed to a method of manufacture of multilayer electrical components, especially capacitors, and components made by such a method. High capacitance dielectric materials and low cost metallizations layered with such dielectrics may be fabricated as multilayer electrical components by sintering the metallizations and the dielectrics during the fabrication process by application of microwave radiation.

Electron Beam Freeform Fabrication Technology Development for Aerospace Applications

NASA Technical Reports Server (NTRS)

Taminger, Karen M.

2006-01-01

NASA Langley has developed a the EBF(sup 3)process and currently has two EBF(sup 3) systems in house. EBF(sup 3) process offers potential cost reduction and fabrication of complex unitized structures out of metals. EBF(sup 3) has been successfully demonstrated on Al, Al-Li, Ti, and Ni alloys to date.

Solar Energy: Materials, Materials Handling, and Fabrication Processes: Student Material. First Edition.

ERIC Educational Resources Information Center

Bolin, William Everet; Orsak, Charles G., Jr.

Designed for student use in "Materials, Materials Handling, and Fabrication Processes," one of 11 courses in a 2-year associate degree program in solar technology, this manual provides readings, exercises, worksheets, bibliographies, and illustrations for 13 course modules. The manual, which corresponds to an instructor guide for the…

Microsacle PolySilicon Hemispherical Shell Resonating Gyroscopes with Integrated Three-dimensional Curved Electrodes

NASA Astrophysics Data System (ADS)

Zhuang, Xuye; Chen, Binggen; Wang, Xinlong; Yu, Lei; Wang, Fan; Guo, Shuwen

2018-03-01

A novel approach for fabrication of polysilicon hemispherical resonator gyroscopes with integrated 3-D curved electrodes is developed and experimentally demonstrated. The 3-D polysilicon electrodes are integrated as a part of the hemispherical shell resonator’s fabrication process, and no extra assembly process are needed, ensuring the symmetry of the shell resonator. The fabrication process and materials used are compatible with the traditional semiconductor process, indicating the gyroscope has a high potential for mass production and commercial development. Without any trimming or tuning of the n=2 wineglass frequencies, a 28 kHz shell resonator demonstrates a 0.009% frequency mismatch between two degenerate wineglass modes, and a 13.6 kHz resonator shows a frequency split of 0.03%. The ring-down time of a fabricated resonator is 0.51 s, corresponding to a Q of 22000, at 0.01 Pa vacuum and room temperature. The prototype of the gyroscope is experimentally analyzed, and the scale factor of the gyro is 1.15 mV/°/s, the bias instability is 80 °/h.

Epoxy/Glass and Polyimide (LaRC(TradeMark) PETI-8)/Carbon Fiber Metal Laminates Made by the VARTM Process

NASA Technical Reports Server (NTRS)

Cano, Roberto J.; Loos, Alfred C.; Jensen, Brian J.; Britton, Sean M.; Tuncol, Goker; Long, Kai

2010-01-01

Recent work at NASA Langley Research Center (LaRC) has concentrated on developing new polyimide resin systems for advanced aerospace applications that can be processed without the use of an autoclave. Polyimide composites are very attractive for applications that require a high strength to weight ratio and thermal stability. Vacuum assisted resin transfer molding (VARTM) has shown the potential to reduce the manufacturing cost of composite structures. Fiber metal laminates (FML) made via this process with aluminum, glass fabric, and epoxy resins have been previously fabricated at LaRC. In this work, the VARTM process has been refined for epoxy/glass FMLs and extended to the fabrication of FM Ls with titanium/carbon fabric layers and a polyimide system developed at NASA, LARC(TradeMark) PETI-8. Resin flow pathways were introduced into the titanium foils to aid the infiltration of the polyimide resin. Injection temperatures in the range of 250-280 C were required to achieve the necessary VARTM viscosities (<10 Poise). Laminate quality and initial mechanical properties will be presented.

Poly-silicon TFT AM-OLED on thin flexible metal substrates

NASA Astrophysics Data System (ADS)

Afentakis, Themis; Hatalis, Miltiadis K.; Voutsas, Apostolos T.; Hartzell, John W.

2003-05-01

Thin metal foils present an excellent alternative to polymers for the fabrication of large area, flexible displays. Their main advantage spurs from their ability to withstand higher temperatures during processing; microelectronic fabrication at elevated temperatures offers the ability to utilize a variety of crystallization processes for the active layer of devices and thermally grown gate dielectrics. This can lead to high performance (high mobility, low threshold voltage) low cost and highly reliable thin film transistors. In some cases, the conductive substrate can also be used to provide power to the active devices, thus reducing layout complexity. This paper discusses the first successful attempt to design and fabricate a variety of active matrix organic light emitting diode displays on thin, flexible stainless steel foils. Different pixel architectures, such as two- and four-transistor implementations, and addressing modes, such as voltage- or current-driven schemese are examined. This work clearly demonstrates the advantages associated with the fabrication of OLED displays on thin metal foils, which - through roll-to-roll processing - can potentially result in revolutionizing today's display processing, leading to a new generation of low cost, high performance versatile display systems.

Analysis of current driving capability of pentacene TFTs for OLEDs

NASA Astrophysics Data System (ADS)

Ryu, Gi Seong; Byun, Hyun Sook; Xu, Yong Xian; Pyo, Kyung Soo; Choe, Ki Beom; Song, Chung Kun

2005-01-01

The flexible display and the application of Roll-To-Roll process is difficult because high temperature process of a-Si;H TFT and poly-Si TFT limited the use of plastic substrate. We proposed AMOLED using Pentacene TFT (OTFT) to fabricate flexible display. The first stage for OTFT application to OLED, we analyzed OTFT as driving device of OLED. The process performed on glass and plastic (PET) substrate that is coated ITO and PVP is used for gate insulator. The field effect mobility of the fabricated OTFT is 0.1~0.3cm2/V"sec and Ion/Ioff current ratio is 103~105. OLED is fabricated with two stories structure of TPD and Alq3, and we can observe the light at 5V by the naked eye. The wavelength of observed lights is 530nm ~550nm. We can confirm the driving of OLED due to OTFT using Test panel and observe OLED control by gate voltage of OTFT. Also, we verify designed structure and process, and make a demonstration fabricating 64 by 64 backplane based on Test panel.

Control of the interaction strength of photonic molecules by nanometer precise 3D fabrication.

PubMed

Rawlings, Colin D; Zientek, Michal; Spieser, Martin; Urbonas, Darius; Stöferle, Thilo; Mahrt, Rainer F; Lisunova, Yuliya; Brugger, Juergen; Duerig, Urs; Knoll, Armin W

2017-11-28

Applications for high resolution 3D profiles, so-called grayscale lithography, exist in diverse fields such as optics, nanofluidics and tribology. All of them require the fabrication of patterns with reliable absolute patterning depth independent of the substrate location and target materials. Here we present a complete patterning and pattern-transfer solution based on thermal scanning probe lithography (t-SPL) and dry etching. We demonstrate the fabrication of 3D profiles in silicon and silicon oxide with nanometer scale accuracy of absolute depth levels. An accuracy of less than 1nm standard deviation in t-SPL is achieved by providing an accurate physical model of the writing process to a model-based implementation of a closed-loop lithography process. For transfering the pattern to a target substrate we optimized the etch process and demonstrate linear amplification of grayscale patterns into silicon and silicon oxide with amplification ratios of ∼6 and ∼1, respectively. The performance of the entire process is demonstrated by manufacturing photonic molecules of desired interaction strength. Excellent agreement of fabricated and simulated structures has been achieved.

Mechanically flexible optically transparent silicon fabric with high thermal budget devices from bulk silicon (100)

NASA Astrophysics Data System (ADS)

Hussain, Muhammad M.; Rojas, Jhonathan P.; Torres Sevilla, Galo A.

2013-05-01

Today's information age is driven by silicon based electronics. For nearly four decades semiconductor industry has perfected the fabrication process of continuingly scaled transistor - heart of modern day electronics. In future, silicon industry will be more pervasive, whose application will range from ultra-mobile computation to bio-integrated medical electronics. Emergence of flexible electronics opens up interesting opportunities to expand the horizon of electronics industry. However, silicon - industry's darling material is rigid and brittle. Therefore, we report a generic batch fabrication process to convert nearly any silicon electronics into a flexible one without compromising its (i) performance; (ii) ultra-large-scale-integration complexity to integrate billions of transistors within small areas; (iii) state-of-the-art process compatibility, (iv) advanced materials used in modern semiconductor technology; (v) the most widely used and well-studied low-cost substrate mono-crystalline bulk silicon (100). In our process, we make trenches using anisotropic reactive ion etching (RIE) in the inactive areas (in between the devices) of a silicon substrate (after the devices have been fabricated following the regular CMOS process), followed by a dielectric based spacer formation to protect the sidewall of the trench and then performing an isotropic etch to create caves in silicon. When these caves meet with each other the top portion of the silicon with the devices is ready to be peeled off from the bottom silicon substrate. Release process does not need to use any external support. Released silicon fabric (25 μm thick) is mechanically flexible (5 mm bending radius) and the trenches make it semi-transparent (transparency of 7%).

Olivine fabrics and tectonic evolution of fore-arc mantles: A natural perspective from the Songshugou dunite and harzburgite in the Qinling orogenic belt, central China

NASA Astrophysics Data System (ADS)

Cao, Yi; Jung, Haemyeong; Song, Shuguang

2017-03-01

To advance our understanding of the deformation characteristics, rheological behaviors, and tectonic evolution of the fore-arc lithospheric mantle, we analyzed mineral fabrics for a large spinel-bearing ultramafic massif in the Songshugou area in the Qinling orogenic belt, central China. In the spinel-poor coarse-grained dunite, stronger A/D-type and weaker C-type-like fabrics were found, whereas the spinel-rich coarse-grained dunite displayed a comparatively stronger B-type-like fabric. These olivine fabrics are high-T fabrics influenced by the presence of melt, in which B and C-type-like fabrics are inferred to be produced by melt-assisted grain boundary sliding during synkinematic high-T melt-rock reactions. In contrast, the spinel-poor porphyroclastic and fine-grained dunites present weak AG and B-type-like fabrics, respectively. Their olivine fabrics (low-T fabrics) are inferred to transform from A/D-type fabric in their coarse-grained counterparts possibly through mylonitization process assisted by low-T fluid-rock reactions, during which strain was accommodated by the fluid-enhanced dislocation slip and/or fluid-assisted grain boundary sliding processes. Combined with the tectonic results of our previous work, the high-T olivine fabrics are probably related to a young and warm fore-arc mantle where intense partial melting and high-T boninitic melt-rock reactions prevalently occurred, whereas the low-T olivine fabrics likely reflect the evolving tectonic settings through the cooling fore-arc mantle to a continental lower crust in a collisional orogeny where low-T fluid-rock reactions were pervasively activated. These low-T olivine fabrics imply that though cold, the fore-arc lithospheric mantle may be locally weak (˜20-30 MPa), allowing ductile deformation to occur at a geologically significant strain rate.

Gas impermeable glaze for sealing a porous ceramic surface

DOEpatents

Reed, Scott T.; Stone, Ronald G.; Nenoff, Tina M.; Trudell, Daniel E.; Thoma, Steven G.

2004-04-06

A process for fabricating a gas impermeable seal on a porous ceramic surface using a thin, glass-based, pinhole free glaze. The process can be used to fabricate gas impermeable end seals on porous alumina tubes used as filter media. The porous alumina tubes can have an inorganic microporous thin film separation membrane on the inner surface, which can be used for high temperature gas separation processes.

Flexible ITO-free organic solar cells applying aqueous solution-processed V2O5 hole transport layer: An outdoor stability study

NASA Astrophysics Data System (ADS)

Lima, F. Anderson S.; Beliatis, Michail J.; Roth, Bérenger; Andersen, Thomas R.; Bortoti, Andressa; Reyna, Yegraf; Castro, Eryza; Vasconcelos, Igor F.; Gevorgyan, Suren A.; Krebs, Frederik C.; Lira-Cantu, Mónica

2016-02-01

Solution processable semiconductor oxides have opened a new paradigm for the enhancement of the lifetime of thin film solar cells. Their fabrication by low-cost and environmentally friendly solution-processable methods makes them ideal barrier (hole and electron) transport layers. In this work, we fabricate flexible ITO-free organic solar cells (OPV) by printing methods applying an aqueous solution-processed V2O5 as the hole transport layer (HTL) and compared them to devices applying PEDOT:PSS. The transparent conducting electrode was PET/Ag/PEDOT/ZnO, and the OPV configuration was PET/Ag/PEDOT/ZnO/P3HT:PC60BM/HTL/Ag. Outdoor stability analyses carried out for more than 900 h revealed higher stability for devices fabricated with the aqueous solution-processed V2O5.

Sandia Advanced MEMS Design Tools v. 3.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yarberry, Victor R.; Allen, James J.; Lantz, Jeffrey W.

This is a major revision to the Sandia Advanced MEMS Design Tools. It replaces all previous versions. New features in this version: Revised to support AutoCAD 2014 and 2015 This CD contains an integrated set of electronic files that: a) Describe the SUMMiT V fabrication process b) Provide enabling educational information (including pictures, videos, technical information) c) Facilitate the process of designing MEMS with the SUMMiT process (prototype file, Design Rule Checker, Standard Parts Library) d) Facilitate the process of having MEMS fabricated at Sandia National Laboratories e) Facilitate the process of having post-fabrication services performed. While there exists somemore » files on the CD that are used in conjunction with software package AutoCAD, these files are not intended for use independent of the CD. Note that the customer must purchase his/her own copy of AutoCAD to use with these files.« less

Analog tree-organized multiplexer

NASA Technical Reports Server (NTRS)

Crabbe, J. S.; Smith, D. M.; Turner, W. R.

1971-01-01

An analog tree-organized multiplexer (ATOM) which is intended for use in the telemetry system of an interplanetary spacecraft is designed. The ATOM will be fabricated by a monolithic, dielectric isolation process, and will contain silicon junction field effect transistors (JFET) as the active elements. The effect of the radiation environment on the performance of the ATOM is analyzed. The result indicates that the expected radiation environment will cause only minor changes in the preradiation characteristics of ATOM. The JFET in the ATOM is designed to meet the electrical requirements when fabricated by either the double poly-dielectric isolation process or the raised dielectric isolation process. The effect of the heat treatment required for the dielectric isolation process on the diffusion profile of the JFET is described. The layout of the ATOM circuit for fabrication by either the double poly or raised dielectric isolation process is also given.

Analysis of the temperature of the hot tool in the cut of woven fabric using infrared images

NASA Astrophysics Data System (ADS)

Borelli, Joao E.; Verderio, Leonardo A.; Gonzaga, Adilson; Ruffino, Rosalvo T.

2001-03-01

Textile manufacture occupies a prominence place in the national economy. By virtue of its importance researches have been made on the development of new materials, equipment and methods used in the production process. The cutting of textiles starts in the basic stage, to be followed within the process of the making of clothes and other articles. In the hot cutting of fabric, one of the variables of great importance in the control of the process is the contact temperature between the tool and the fabric. The work presents a technique for the measurement of the temperature based on the processing of infrared images. For this a system was developed composed of an infrared camera, a framegrabber PC board and software that analyzes the punctual temperature in the cut area enabling the operator to achieve the necessary control of the other variables involved in the process.

Limiting factors in the production of deep microstructures

NASA Astrophysics Data System (ADS)

Tolfree, David W. L.; O'Neill, William; Tunna, Leslie; Sutcliffe, Christopher

1999-10-01

Microsystems increasingly require precision deep microstructures that can be cost-effectively designed and manufactured. New products must be able to meet the demands of the rapidly growing markets for microfluidic, micro- optical and micromechanical devices in industrial sectors which include chemicals, pharmaceuticals, biosciences, medicine and food. The realization of such products, first requires an effective process to design and manufacture prototypes. Two process methods used for the fabrication of high aspect-ratio microstructures are based on X-ray beam lithography with electroforming processes and direct micromachining with a frequency multiplied Nd:YAG laser using nanosecond pulse widths. Factors which limit the efficiency and precision obtainable using such processes are important parameters when deciding on the best fabrication method to use. A basic microstructure with narrow channels suitable for a microfluidic mixer have been fabricated using both these techniques and comparisons made of the limitations and suitability of the processes in respect of fast prototyping and manufacture or working devices.

Effect of microwave argon plasma on the glycosidic and hydrogen bonding system of cotton cellulose.

PubMed

Prabhu, S; Vaideki, K; Anitha, S

2017-01-20

Cotton fabric was processed with microwave (Ar) plasma to alter its hydrophilicity. The process parameters namely microwave power, process gas pressure and processing time were optimized using Box-Behnken method available in the Design Expert software. It was observed that certain combinations of process parameters improved existing hydrophilicity while the other combinations decreased it. ATR-FTIR spectral analysis was used to identify the strain induced in inter chain, intra chain, and inter sheet hydrogen bond and glycosidic covalent bond due to plasma treatment. X-ray diffraction (XRD) studies was used to analyze the effect of plasma on unit cell parameters and degree of crystallinity. Fabric surface etching was identified using FESEM analysis. Thus, it can be concluded that the increase/decrease in the hydrophilicity of the plasma treated fabric was due to these structural and physical changes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Design and grayscale fabrication of beamfanners in a silicon substrate

NASA Astrophysics Data System (ADS)

Ellis, Arthur Cecil

2001-11-01

This dissertation addresses important first steps in the development of a grayscale fabrication process for multiple phase diffractive optical elements (DOS's) in silicon. Specifically, this process was developed through the design, fabrication, and testing of 1-2 and 1-4 beamfanner arrays for 5-micron illumination. The 1-2 beamfanner arrays serve as a test-of- concept and basic developmental step toward the construction of the 1-4 beamfanners. The beamfanners are 50 microns wide, and have features with dimensions of between 2 and 10 microns. The Iterative Annular Spectrum Approach (IASA) method, developed by Steve Mellin of UAH, and the Boundary Element Method (BEM) are the design and testing tools used to create the beamfanner profiles and predict their performance. Fabrication of the beamfanners required the techniques of grayscale photolithography and reactive ion etching (RIE). A 2-3micron feature size 1-4 silicon beamfanner array was fabricated, but the small features and contact photolithographic techniques available prevented its construction to specifications. A second and more successful attempt was made in which both 1-4 and 1-2 beamfanner arrays were fabricated with a 5-micron minimum feature size. Photolithography for the UAH array was contracted to MEMS-Optical of Huntsville, Alabama. A repeatability study was performed, using statistical techniques, of 14 photoresist arrays and the subsequent RIE process used to etch the arrays in silicon. The variance in selectivity between the 14 processes was far greater than the variance between the individual etched features within each process. Specifically, the ratio of the variance of the selectivities averaged over each of the 14 etch processes to the variance of individual feature selectivities within the processes yielded a significance level below 0.1% by F-test, indicating that good etch-to-etch process repeatability was not attained. One of the 14 arrays had feature etch-depths close enough to design specifications for optical testing, but 5- micron IR illumination of the 1-4 and 1-2 beamfanners yielded no convincing results of beam splitting in the detector plane 340 microns from the surface of the beamfanner array.

Cavitation controlled acoustic probe for fabric spot cleaning and moisture monitoring

DOEpatents

Sheen, Shuh-Haw; Chien, Hual-Te; Raptis, Apostolos C.

1997-01-01

A method and apparatus are provided for monitoring a fabric. An acoustic probe generates acoustic waves relative to the fabric. An acoustic sensor, such as an accelerometer is coupled to the acoustic probe for generating a signal representative of cavitation activity in the fabric. The generated cavitation activity representative signal is processed to indicate moisture content of the fabric. A feature of the invention is a feedback control signal is generated responsive to the generated cavitation activity representative signal. The feedback control signal can be used to control the energy level of the generated acoustic waves and to control the application of a cleaning solution to the fabric.

Preview of the NASA NNWG NDE Sample Preparation Handbook

NASA Technical Reports Server (NTRS)

2010-01-01

This viewgraph presents a step-by-step how-to fabrication documentation of every kind of sample that is fabricated for MSFC by UA Huntsville, including photos and illustrations. The tabulation of what kind of samples are being fabricated for what NDE method, detailed instructions/documentation of the inclusion/creation of defects, detailed specifications for materials, processes, and equipment, case histories and/or experiences with the different fabrication methods and defect inclusion techniques, discussion of pitfalls and difficulties associated with sample fabrication and defect inclusion techniques, and a discussion of why certain fabrication techniques are needed as related to the specific NDE methods are included in this presentation.

Analysis of knitted fabric reinforced flexible composites and applications in thermoforming

NASA Astrophysics Data System (ADS)

Bekisli, Burak

In this study, large deformation behavior of knitted fabric reinforced composites is investigated. In order to fully utilize the unique stretchability of knitted fabric reinforcements, elastomeric materials are used as the matrix material, resulting in "flexible composites" capable of reaching several hundred percent stretch before failing. These non-traditional composites are ideal candidates for many engineering applications where large deformation is desired, including energy/impact absorption and novel forming processes. A multi-level nonlinear finite element (FE) procedure is developed to analyze the deformation behavior of plain weft-knitted fabrics and the composites derived from these materials. The hierarchy of the model is composed of a 3D unit cell analysis (micro/meso-scale) and a 2D global analysis (macro scale). Using results from different numerical experiments performed in the micro/meso scale, a mechanical behavior database of knit fabric geometries is constructed, both for the uniaxial and biaxial stretch cases. Through an optimization procedure, these results are used to determine the mechanical properties of nonlinear truss elements needed for modeling in the macro scale. A hexagonal honeycomb structure, which closely resembles the knit fabric architecture, is formed using these nonlinear trusses. This truss structure is then used to efficiently model a large number of loops generally found in a fabric. Results from uniaxial experimental measurements are presented for knitted fabrics to validate the FE model. Appropriate hyperelastic material models are determined for the elastomeric matrix, using a curve fit to experimental data. Examples of raw fabric and composite deformation simulations in the global scale are presented in this study. Two types of composites are studied experimentally and numerically: (1) knitted fabric embedded in an elastomeric medium, and (2) the sandwich type composites with elastomeric skins and fabric core. The strain energy dissipation is found to be superior in the latter case, since yarns are not restricted by the elastomer. In addition, yarns used in this type of composite move to effectively align along the load direction, yielding a better utilization of the fibers' high axial stiffness. Fabrication methods, including novel techniques involving twin-sheet thermoforming, for both types of composites are discussed. Tensile test results for glassfiber reinforced, TPE/polyurea based specimens are also presented. Innovative concepts related to the thermoforming process are also investigated using the developed numerical model. It is shown that some of the most critical problems in this forming process, such as non-uniform thickness distribution in the final part and the sensitivity of part quality to minor thermal variations, can be beneficially addressed using carefully "tailored" knit fabrics. Common thermoformed part geometries, such as a 3D box corner and a long U-shaped channel, are studied in numerical simulations to illustrate the effects of knitted fabric reinforcements on the stabilization of the forming process.

Nano-fabricated size exclusion chromatograph

NASA Technical Reports Server (NTRS)

Svehla, D.; Feldman, S.; Feldman, J.; Grunthaner, F.; Shakkottai, P.; Castillo, L. del; White, V.

2002-01-01

This paper describes the development of a nano-fabricated size exclusion chromatograph (nSEC) based on the principle that molecules traveling through amicrocolumn containing nano-fabricated features will have characteristic elution times that directly correlate to molecular weight. Compared to conventional size exclusion chromatography, the nSEC offers greater control over the size exclusion process; mass fabrication; integration of the separation column with associated valves, pumps, and detectors; and dramatic reductions in instrument mass and power requirements.

Development of nanoimprint lithography templates for the contact hole layer application (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ichimura, Koji; Hikichi, Ryugo; Harada, Saburo; Kanno, Koichi; Kurihara, Masaaki; Hayashi, Naoya

2017-04-01

Nanoimprint lithography, NIL, is gathering much attention as one of the most potential candidates for the next generation lithography for semiconductor. This technology needs no pattern data modification for exposure, simpler exposure system, and single step patterning process without any coat/develop truck, and has potential of cost effective patterning rather than very complex optical lithography and/or EUV lithography. NIL working templates are made by the replication of the EB written high quality master templates. Fabrication of high resolution master templates is one of the most important issues. Since NIL is 1:1 pattern transfer process, master templates have 4 times higher resolution compared with photomasks. Another key is to maintain the quality of the master templates in replication process. NIL process is applied for the template replication and this imprint process determines most of the performance of the replicated templates. Expectations to the NIL are not only high resolution line and spaces but also the contact hole layer application. Conventional ArF-i lithography has a certain limit in size and pitch for contact hole fabrication. On the other hand, NIL has good pattern fidelity for contact hole fabrication at smaller sizes and pitches compared with conventional optical lithography. Regarding the tone of the templates for contact hole, there are the possibilities of both tone, the hole template and the pillar template, depending on the processes of the wafer side. We have succeeded to fabricate both types of templates at 2xnm in size. In this presentation, we will be discussing fabrication or our replica template for the contact hole layer application. Both tone of the template fabrication will be presented as well as the performance of the replica templates. We will also discuss the resolution improvement of the hole master templates by using various e-beam exposure technologies.

Electrospinning for nano- to mesoscale photonic structures

NASA Astrophysics Data System (ADS)

Skinner, Jack L.; Andriolo, Jessica M.; Murphy, John P.; Ross, Brandon M.

2017-08-01

The fabrication of photonic and electronic structures and devices has directed the manufacturing industry for the last 50 years. Currently, the majority of small-scale photonic devices are created by traditional microfabrication techniques that create features by processes such as lithography and electron or ion beam direct writing. Microfabrication techniques are often expensive and slow. In contrast, the use of electrospinning (ES) in the fabrication of micro- and nano-scale devices for the manipulation of photons and electrons provides a relatively simple and economic viable alternative. ES involves the delivery of a polymer solution to a capillary held at a high voltage relative to the fiber deposition surface. Electrostatic force developed between the collection plate and the polymer promotes fiber deposition onto the collection plate. Issues with ES fabrication exist primarily due to an instability region that exists between the capillary and collection plate and is characterized by chaotic motion of the depositing polymer fiber. Material limitations to ES also exist; not all polymers of interest are amenable to the ES process due to process dependencies on molecular weight and chain entanglement or incompatibility with other polymers and overall process compatibility. Passive and active electronic and photonic fibers fabricated through the ES have great potential for use in light generation and collection in optical and electronic structures/devices. ES produces fiber devices that can be combined with inorganic, metallic, biological, or organic materials for novel device design. Synergistic material selection and post-processing techniques are also utilized for broad-ranging applications of organic nanofibers that span from biological to electronic, photovoltaic, or photonic. As the ability to electrospin optically and/or electronically active materials in a controlled manner continues to improve, the complexity and diversity of devices fabricated from this process can be expected to grow rapidly and provide an alternative to traditional resource-intensive fabrication techniques.

A cochlear implant fabricated using a bulk silicon-surface micromachining process

NASA Astrophysics Data System (ADS)

Bell, Tracy Elizabeth

1999-11-01

This dissertation presents the design and fabrication of two generations of a silicon microelectrode array for use in a cochlear implant. A cochlear implant is a device that is inserted into the inner ear and uses electrical stimulation to provide sound sensations to the profoundly deaf. The first-generation silicon cochlear implant is a passive device fabricated using silicon microprobe technology developed at the University of Michigan. It contains twenty-two iridium oxide (IrO) stimulating sites that are 250 mum in diameter and spaced at 750 mum intervals. In-vivo recordings were made in guinea pig auditory cortex in response to electrical stimulation with this device, verifying its ability to electrically evoke an auditory response. Auditory thresholds as low as 78 muA were recorded. The second-generation implant is a thirty-two site, four-channel device with on-chip CMOS site-selection circuitry and integrated position sensing. It was fabricated using a novel bulk silicon surface micromachining process which was developed as a part of this dissertation work. While the use of semiconductor technology offers many advantages in fabricating cochlear implants over the methods currently used, it was felt that even further advantages could be gained by developing a new micromachining process which would allow circuitry to be distributed along the full length of the cochlear implant substrate. The new process uses electropolishing of an n+ bulk silicon sacrificial layer to undercut and release n- epitaxial silicon structures from the wafer. An extremely abrupt etch-stop between the n+ and n- silicon is obtained, with no electropolishing taking place in the n-type silicon that is doped lower than 1 x 1017 cm-3 in concentration. Lateral electropolishing rates of up to 50 mum/min were measured using this technique, allowing one millimeter-wide structures to be fully undercut in as little as 10 minutes. The new micromachining process was integrated with a standard p-well CMOS integrated circuit process to fabricate the second-generation active silicon cochlear implants.

A low-cost photovoltaic cell process based on thick film techniques

NASA Technical Reports Server (NTRS)

Mardesich, N.; Pepe, A.; Bunyan, S.; Edwards, B.; Olson, C.

1980-01-01

The low-cost, easily automated processing for solar cell fabrication being developed at Spectrolab for the DOE LSA program is described. These processes include plasma-etching, spray-on diffusion sources and antireflective coating, thick film metallization, aluminum back contacts, laser scribing and ultrasonic soldering. The process sequence has been shown to produce solar cells having 15% conversion efficiency at AM1 which meet the cell fabrication budget required for the DOE 1986 cost goal of $0.70 per peak watt in 1980.

Investigation of proposed process sequence for the array automated assembly task, phases 1 and 2

NASA Technical Reports Server (NTRS)

Mardesich, N.; Garcia, A.; Eskenas, K.

1980-01-01

Progress was made on the process sequence for module fabrication. A shift from bonding with a conformal coating to laminating with ethylene vinyl acetate and a glass superstrate is recommended for further module fabrication. The processes that were retained for the selected process sequence, spin-on diffusion, print and fire aluminum p+ back, clean, print and fire silver front contact and apply tin pad to aluminum back, were evaluated for their cost contribution.

Self-Reacting Friction Stir Welding for Aluminum Complex Curvature Applications

NASA Technical Reports Server (NTRS)

Brown, Randy J.; Martin, W.; Schneider, J.; Hartley, P. J.; Russell, Carolyn; Lawless, Kirby; Jones, Chip

2003-01-01

This viewgraph representation provides an overview of sucessful research conducted by Lockheed Martin and NASA to develop an advanced self-reacting friction stir technology for complex curvature aluminum alloys. The research included weld process development for 0.320 inch Al 2219, sucessful transfer from the 'lab' scale to the production scale tool and weld quality exceeding strenght goals. This process will enable development and implementation of large scale complex geometry hardware fabrication. Topics covered include: weld process development, weld process transfer, and intermediate hardware fabrication.

Contact-eutectic-lens fabrication technique

NASA Technical Reports Server (NTRS)

Allen, F. G.; Yue, A. S.; Yu, J. G.

1975-01-01

Method enables use of crystal or semiconductor materials with selective spectral-response characteristics (ultraviolet, visible, or infrared wavelengths) in fabrication of contact lenses, reading glasses, and photographic processing equipment.

16 CFR 1616.31 - Labeling, recordkeeping, retail display and guaranties.

Code of Federal Regulations, 2014 CFR

2014-01-01

... process of manufacture of each production unit of articles of children's sleepwear, or fabrics or related... content, and details of construction on all seams, fabrics, threads, stitches, and trims used in each... sufficient to repeat the prototype tests required by § 1616.4 of the Standard for all fabrics, seams, threads...

16 CFR § 1616.31 - Labeling, recordkeeping, retail display and guaranties.

Code of Federal Regulations, 2013 CFR

2013-01-01

... process of manufacture of each production unit of articles of children's sleepwear, or fabrics or related... content, and details of construction on all seams, fabrics, threads, stitches, and trims used in each... sufficient to repeat the prototype tests required by § 1616.4 of the Standard for all fabrics, seams, threads...

16 CFR 1616.31 - Labeling, recordkeeping, retail display and guaranties.

Code of Federal Regulations, 2011 CFR

2011-01-01

... process of manufacture of each production unit of articles of children's sleepwear, or fabrics or related... content, and details of construction on all seams, fabrics, threads, stitches, and trims used in each... sufficient to repeat the prototype tests required by § 1616.4 of the Standard for all fabrics, seams, threads...

16 CFR 1616.31 - Labeling, recordkeeping, retail display and guaranties.

Code of Federal Regulations, 2012 CFR

2012-01-01

... process of manufacture of each production unit of articles of children's sleepwear, or fabrics or related... content, and details of construction on all seams, fabrics, threads, stitches, and trims used in each... sufficient to repeat the prototype tests required by § 1616.4 of the Standard for all fabrics, seams, threads...

Thin silicon-solar cell fabrication

NASA Technical Reports Server (NTRS)

Lindmayer, J.

1979-01-01

Flexible silicon slices of uniform thicknesses are fabricated by etching in sodium hydroxide solution. Maintaining uniform thickness across slices during process(fabrication) is important for cell strength and resistance to damage in handling. Slices formed by procedure have reproducible surface with fine orange peel texture, and are far superior to slices prepared by other methods.

Fabrication of silicon-based shape memory alloy micro-actuators

NASA Technical Reports Server (NTRS)

Johnson, A. David; Busch, John D.; Ray, Curtis A.; Sloan, Charles L.

1992-01-01

Thin film shape memory alloy has been integrated with silicon in a new actuation mechanism for microelectromechanical systems. This paper compares nickel-titanium film with other actuators, describes recent results of chemical milling processes developed to fabricate shape memory alloy microactuators in silicon, and describes simple actuation mechanisms which have been fabricated and tested.

Fabrication and Characterization of SMA Hybrid Composites

NASA Technical Reports Server (NTRS)

Turner, Travis L.; Lach, Cynthia L.; Cano, Robert J.

2001-01-01

Results from an effort to fabrication shape memory alloy hybrid composite (SMAHC) test specimens and characterize the material system are presented in this study. The SMAHC specimens are conventional composite structures with an embedded SMA constituent. The fabrication and characterization work was undertaken to better understand the mechanics of the material system, address fabrication issues cited in the literature, and provide specimens for experimental validation of a recently developed thermomechanical model for SMAHC structures. Processes and hardware developed for fabrication of the SMAHC specimens are described. Fabrication of a SMA14C laminate with quasi-isotropic lamination and ribbon-type Nitinol actuators embedded in the 0' layers is presented. Beam specimens are machined from the laminate and are the focus of recent work, but the processes and hardware are readily extensible to more practical structures. Results of thermomechanical property testing on the composite matrix and Nitinol ribbon are presented. Test results from the Nitinol include stress-strain behavior, modulus versus temperature. and constrained recovery stress versus temperature and thermal cycle. Complex thermomechanical behaviors of the Nitinol and composite matrix are demonstrated, which have significant implications for modeling of SMAHC structures.

Contrast studies of the process optimization and characterization of shielding fabric by amorphous Ni-Fe-P and Ni-P alloy

NASA Astrophysics Data System (ADS)

Yao, Kai; Wu, Xueyan; An, Zhentao

2017-01-01

A flexible shielding fabric with dense uniform coating was prepared after electrical deposition of amorphous Ni-Fe-P and Ni-P alloy on copper-coated polyethylene terephthalate (PET) fabric. The effects of coating composition and the deposition rate were discussed by the current density, temperature and pH value. The morphology, composition, and structure of coating were analyzed by SEM, EDS, and XRD characterizations. The EMI shielding effectiveness and corrosion resistance were also tested. The results fabric possesses dense, smooth, and uniform coating, when the processing conditions are 60°C, pH=1.5, and current density =8.7A/dm2. The coating fabric consists of amorphous Ni-Fe-P alloy with 16.62% P (weight percent), which has excellent of corrosion resistance. By contrast the EMI shielding effectiveness of amorphous Ni-Fe-P was better than amorphous Ni-P. The EMI shielding effectiveness of this coated fabric achieves 69.20dB-80.30dB in a broad frequency range between 300 kHz˜1.5 GHz.

An integrated optical CO2 sensor. Phase 0: Design and fabrication of critical elements

NASA Technical Reports Server (NTRS)

Murphy, Michael C.; Kelly, Kevin W.; Li, B. Q.; Ma, EN; Wang, Wanjun; Vladimirsky, Yuli; Vladimirsky, Olga

1994-01-01

Significant progress has been made toward all of the goals for the first phase of the project short of actual fabrication of a light path. Two alternative approaches to fabricating gold mirrors using the basic LIGA process were developed, one using electroplated solid gold mirrors and the second using gold plated over a nickel base. A new method of fabrication, the transfer mask process, was developed and demonstrated. Analysis of the projected surface roughness and beam divergence effects was completed. With gold surface with low surface roughness scattering losses are expected to be insignificant. Beam divergence due to diffraction will require a modification of the original design, but should be eliminated by fabricating mirrors 1000 mu m in height by 1000 mu m in width and using a source with an initial beam radius greater than 300 mu m. This may eliminate any need for focusing optics. Since the modified design does not affect the mask layout, ordering of the mask and fabrication of the test structures can begin immediately at the start of Phase 1.

Experimental investigation of effects of stitching orientation on forming behaviors of 2D P-aramid multilayer woven preform

NASA Astrophysics Data System (ADS)

Abtew, Mulat Alubel; Boussu, François; Bruniaux, Pascal; Loghin, Carmen; Cristian, Irina; Chen, Yan; Wang, Lichuan

2018-05-01

In many textile applications stitching process is one of the widely used methods to join the multi-layer fabric plies not only due to its easy applicability and flexible production but also provide structural integrity throughout-the-thickness of materials. In this research, the influences of stitching pattern on various molding characteristics of multi-layer 2D para-aramid plain woven fabrics while deformation was investigated. The fabrics were made of high performance fiber with 930dtex yarn linear density and fabric areal density of 200gm/m2. First, different stitch pattern (orientation) was applied for joining the mentioned multi-layered fabrics keeping other stitching parameters such as stitch gap, stitch thread tension, stitch length, stitch type, stitch thread type etc. constant throughout the study. Then, a pneumatic based molding device with a low speed forming process specially designed for preforming of textile with a predefined hemispherical shape of punch. The result shows that stitching pattern is one of the parameter that influences the different molding behavior and should be consider while molding stitched multi-layer fabrics.

Texture and hydride orientation relationship of Zircaloy-4 fuel clad tube during its fabrication for pressurized heavy water reactors

NASA Astrophysics Data System (ADS)

Vaibhaw, Kumar; Rao, S. V. R.; Jha, S. K.; Saibaba, N.; Jayaraj, R. N.

2008-12-01

Zircaloy-4 material is used for cladding tube in pressurized heavy water reactors (PHWRs) of 220 MWe and 540 MWe capacity in India. These tubes are fabricated by using various combinations of thermo-mechanical processes to achieve desired mechanical and corrosion properties. Cladding tube develops crystallographic texture during its fabrication, which has significant influence on its in-reactor performance. Due to radiolytic decomposition of water Zircaloy-4 picks-up hydrogen. This hydrogen in excess of its maximum solubility in reactor operating condition (˜300 °C), precipitates as zirconium hydrides causing embrittlement of cladding tube. Hydride orientation in the radial direction of the tube limits the service life and lowers the fuel burn-up in reactor. The orientation of the hydride primarily depends on texture developed during fabrication. A correlation between hydride orientation ( F n) with the texture in the tube during its fabrication has been developed using a second order polynomial. The present work is aimed at quantification and correlation of texture evolved in Zircaloy-4 cladding tube using Kearn's f-parameter during its fabrication process.

Rapid and high throughput fabrication of high temperature stable structures through PDMS transfer printing

NASA Astrophysics Data System (ADS)

Hohenberger, Erik; Freitag, Nathan; Korampally, Venumadhav

2017-07-01

We report on a facile and low cost fabrication approach for structures—gratings and enclosed nanochannels, through simple solution processed chemistries in conjunction with nanotransfer printing techniques. The ink formulation primarily consisting of an organosilicate polymeric network with a small percentage of added 3-aminopropyl triethoxysilane crosslinker allows one to obtain robust structures that are not only stable towards high temperature processing steps as high as 550 °C but also exhibit exceptional stability against a host of organic solvent washes. No discernable structure distortion was observed compared to the as-printed structures (room temperature processed) when printed structures were subjected to temperatures as high as 550 °C. We further demonstrate the applicability of this technique towards the fabrication of more complex nanostructures such as enclosed channels through a double transfer method, leveraging the exceptional room temperature cross-linking ability of the printed structures and their subsequent resistance to dissolution in organic solvent washes. The exceptional temperature and physico-chemical stability of the nanotransfer printed structures makes this a useful fabrication tool that may be applied as is, or integrated with conventional lithographic techniques for the large area fabrication of functional nanostructures and devices.

Development of software for computing forming information using a component based approach

NASA Astrophysics Data System (ADS)

Ko, Kwang Hee; Park, Jiing Seo; Kim, Jung; Kim, Young Bum; Shin, Jong Gye

2009-12-01

In shipbuilding industry, the manufacturing technology> has advanced at an unprecedented pace for the last decade. As a result, many automatic systems for cutting, welding, etc. have been developed and employed in the manufacturing process and accordingly the productivity has been increased drastically. Despite such improvement in the manufacturing technology', however, development of an automatic system for fabricating a curved hull plate remains at the beginning stage since hardware and software for the automation of the curved hull fabrication process should be developed differently depending on the dimensions of plates, forming methods and manufacturing processes of each shipyard. To deal with this problem, it is necessary> to create a "plug-in ''framework, which can adopt various kinds of hardware and software to construct a full automatic fabrication system. In this paper, a frame-work for automatic fabrication of curved hull plates is proposed, which consists of four components and related software. In particular the software module for computing fabrication information is developed by using the ooCBD development methodology; which can interface with other hardware and software with minimum effort. Examples of the proposed framework applied to medium and large shipyards are presented.

Fabrication of silk fibroin film using centrifugal casting technique for corneal tissue engineering.

PubMed

Lee, Min Chae; Kim, Dong-Kyu; Lee, Ok Joo; Kim, Jung-Ho; Ju, Hyung Woo; Lee, Jung Min; Moon, Bo Mi; Park, Hyun Jung; Kim, Dong Wook; Kim, Su Hyeon; Park, Chan Hum

2016-04-01

Films prepared from silk fibroin have shown potential as biomaterials in tissue engineering applications for the eye. Here, we present a novel process for fabrication of silk fibroin films for corneal application. In this work, fabrication of silk fibroin films was simply achieved by centrifugal force. In contrast to the conventional dry casting method, we carried out the new process in a centrifuge with a rotating speed of 4000 rpm, where centrifugal force was imposed on an aluminum tube containing silk fibroin solution. In the present study, we also compared the surface roughness, mechanical properties, transparency, and cell proliferation between centrifugal and dry casting method. In terms of surface morphology, films fabricated by the centrifugal casting have less surface roughness than those by the dry casting. For elasticity and transparency, silk fibroin films obtained from the centrifugal casting had favorable results compared with those prepared by dry casting. Furthermore, primary human corneal keratocytes grew better in films prepared by the centrifugal casting. Therefore, our results suggest that this new fabrication process for silk fibroin films offers important potential benefits for corneal tissue regeneration. © 2015 Wiley Periodicals, Inc.

Polysaccharide Fabrication Platforms and Biocompatibility Assessment as Candidate Wound Dressing Materials

PubMed Central

Aduba, Donald C.; Yang, Hu

2017-01-01

Wound dressings are critical for wound care because they provide a physical barrier between the injury site and outside environment, preventing further damage or infection. Wound dressings also manage and even encourage the wound healing process for proper recovery. Polysaccharide biopolymers are slowly becoming popular as modern wound dressings materials because they are naturally derived, highly abundant, inexpensive, absorbent, non-toxic and non-immunogenic. Polysaccharide biopolymers have also been processed into biomimetic platforms that offer a bioactive component in wound dressings that aid the healing process. This review primarily focuses on the fabrication and biocompatibility assessment of polysaccharide materials. Specifically, fabrication platforms such as electrospun fibers and hydrogels, their fabrication considerations and popular polysaccharides such as chitosan, alginate, and hyaluronic acid among emerging options such as arabinoxylan are discussed. A survey of biocompatibility and bioactive molecule release studies, leveraging polysaccharide’s naturally derived properties, is highlighted in the text, while challenges and future directions for wound dressing development using emerging fabrication techniques such as 3D bioprinting are outlined in the conclusion. This paper aims to encourage further investigation and open up new, disruptive avenues for polysaccharides in wound dressing material development. PMID:28952482

Fabrication of an infrared Shack-Hartmann sensor by combining high-speed single-point diamond milling and precision compression molding processes.

PubMed

Zhang, Lin; Zhou, Wenchen; Naples, Neil J; Yi, Allen Y

2018-05-01

A novel fabrication method by combining high-speed single-point diamond milling and precision compression molding processes for fabrication of discontinuous freeform microlens arrays was proposed. Compared with slow tool servo diamond broaching, high-speed single-point diamond milling was selected for its flexibility in the fabrication of true 3D optical surfaces with discontinuous features. The advantage of single-point diamond milling is that the surface features can be constructed sequentially by spacing the axes of a virtual spindle at arbitrary positions based on the combination of rotational and translational motions of both the high-speed spindle and linear slides. By employing this method, each micro-lenslet was regarded as a microstructure cell by passing the axis of the virtual spindle through the vertex of each cell. An optimization arithmetic based on minimum-area fabrication was introduced to the machining process to further increase the machining efficiency. After the mold insert was machined, it was employed to replicate the microlens array onto chalcogenide glass. In the ensuing optical measurement, the self-built Shack-Hartmann wavefront sensor was proven to be accurate in detecting an infrared wavefront by both experiments and numerical simulation. The combined results showed that precision compression molding of chalcogenide glasses could be an economic and precision optical fabrication technology for high-volume production of infrared optics.

Fabrication of High Thermal Conductivity NARloy-Z-Diamond Composite Combustion Chamber Liner for Advanced Rocket Engines

NASA Technical Reports Server (NTRS)

Bhat, Biliyar N.; Greene, Sandra E.; Singh, Jogender

2016-01-01

NARloy-Z alloy (Cu-3 percent, Ag-0.5 percent, Zr) is a state of the art alloy currently used for fabricating rocket engine combustion chamber liners. Research conducted at NASA-MSFC and Penn State – Applied Research Laboratory has shown that thermal conductivity of NARloy-Z can be increased significantly by adding diamonds to form a composite (NARloy-Z-D). NARloy-Z-D is also lighter than NARloy-Z. These attributes make this advanced composite material an ideal candidate for fabricating combustion chamber liner for an advanced rocket engine. Increased thermal conductivity will directly translate into increased turbopump power and increased chamber pressure for improved thrust and specific impulse. This paper describes the process development for fabricating a subscale high thermal conductivity NARloy-Z-D combustion chamber liner using Field Assisted Sintering Technology (FAST). The FAST process uses a mixture of NARloy-Z and diamond powders which is sintered under pressure at elevated temperatures. Several challenges were encountered, i.e., segregation of diamonds, machining the super hard NARloy-Z-D composite, net shape fabrication and nondestructive examination. The paper describes how these challenges were addressed. Diamonds coated with copper (CuD) appear to give the best results. A near net shape subscale combustion chamber liner is being fabricated by diffusion bonding cylindrical rings of NARloy-Z-CuD using the FAST process.

A highly manufacturable 0.2 {mu}m AlGaAs/InGaAs PHEMT fabricated using the single-layer integrated-metal FET (SLIMFET) process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Havasy, C.K.; Quach, T.K.; Bozada, C.A.

1995-12-31

This work is the development of a single-layer integrated-metal field effect transistor (SLIMFET) process for a high performance 0.2 {mu}m AlGaAs/InGaAs pseudomorphic high electron mobility transistor (PHEMT). This process is compatible with MMIC fabrication and minimizes process variations, cycle time, and cost. This process uses non-alloyed ohmic contacts, a selective gate-recess etching process, and a single gate/source/drain metal deposition step to form both Schottky and ohmic contacts at the same time.

Development of SiC/SiC composites by PIP in combination with RS

NASA Astrophysics Data System (ADS)

Kotani, Masaki; Kohyama, Akira; Katoh, Yutai

2001-02-01

In order to improve the mechanical performances of SiC/SiC composite, process improvement and modification of polymer impregnation and pyrolysis (PIP) and reaction sintering (RS) process were investigated. The fibrous prepregs were prepared by a polymeric intra-bundle densification technique using Tyranno-SA™ fiber. For inter-bundle matrix, four kinds of process options utilizing polymer pyrolysis and reaction sintering were studied. The process conditions were systematically optimized through fabricating monoliths. Then, SiC/SiC composites were fabricated using optimized inter-bundle matrix slurries in each process for the first inspection of process requirements.

Peel-and-Stick: Mechanism Study for Efficient Fabrication of Flexible/Transparent Thin-film Electronics

NASA Astrophysics Data System (ADS)

Lee, Chi Hwan; Kim, Jae-Han; Zou, Chenyu; Cho, In Sun; Weisse, Jeffery M.; Nemeth, William; Wang, Qi; van Duin, Adri C. T.; Kim, Taek-Soo; Zheng, Xiaolin

2013-10-01

Peel-and-stick process, or water-assisted transfer printing (WTP), represents an emerging process for transferring fully fabricated thin-film electronic devices with high yield and fidelity from a SiO2/Si wafer to various non-Si based substrates, including papers, plastics and polymers. This study illustrates that the fundamental working principle of the peel-and-stick process is based on the water-assisted subcritical debonding, for which water reduces the critical adhesion energy of metal-SiO2 interface by 70 ~ 80%, leading to clean and high quality transfer of thin-film electronic devices. Water-assisted subcritical debonding is applicable for a range of metal-SiO2 interfaces, enabling the peel-and-stick process as a general and tunable method for fabricating flexible/transparent thin-film electronic devices.

Peel-and-stick: mechanism study for efficient fabrication of flexible/transparent thin-film electronics.

PubMed

Lee, Chi Hwan; Kim, Jae-Han; Zou, Chenyu; Cho, In Sun; Weisse, Jeffery M; Nemeth, William; Wang, Qi; van Duin, Adri C T; Kim, Taek-Soo; Zheng, Xiaolin

2013-10-10

Peel-and-stick process, or water-assisted transfer printing (WTP), represents an emerging process for transferring fully fabricated thin-film electronic devices with high yield and fidelity from a SiO2/Si wafer to various non-Si based substrates, including papers, plastics and polymers. This study illustrates that the fundamental working principle of the peel-and-stick process is based on the water-assisted subcritical debonding, for which water reduces the critical adhesion energy of metal-SiO2 interface by 70 ~ 80%, leading to clean and high quality transfer of thin-film electronic devices. Water-assisted subcritical debonding is applicable for a range of metal-SiO2 interfaces, enabling the peel-and-stick process as a general and tunable method for fabricating flexible/transparent thin-film electronic devices.

Infusion Processing of Phenylethynyl Terminated Imides by High Temperature RTM and VARTM

NASA Technical Reports Server (NTRS)

Ghose, Sayata; Lewis, Todd M.; Cano, Roberto J.; Watson, Kent A.; Isayev, Avraam I.

2011-01-01

Fabrication of composite structures using infusion processes such as resin transfer molding (RTM) and vacuum assisted resin transfer molding (VARTM) is generally more affordable than conventional autoclave techniques. Recent efforts have focused on adapting both technologies for the fabrication of high temperature (HT) resistant composites. Due to their low melt viscosity and long melt stability, certain phenylethynyl terminated imides (PETI) can be processed into composites using these high temperature out-of-autoclave processes. In the current study, two PETI resins, LARC(TradeMark) PETI-330 and LARC(TradeMark) PETI-8 have been used to make test specimens using both RTM and VARTM. For aerospace applications, a void fraction of less than 2% is desired. Traditionally, RTM has had the advantage over VARTM for generating composites with low void content. However, the process is limited in terms of size. Work at NASA LaRC has incorporated modifications to the thermal cycle used in laminate fabrication that have reduced the void content significantly (typically 1-3%) using the current HT-VARTM process. For composite fabrication by both RTM and VARTM, the resins were infused into three carbon fiber preforms (T650-35-3k 5HS, IM7-6k 5HS, and IM7-6k Uniweave) at 316 C and 260 C respectively and cured up to 371 C. The details of the RTM processing carried out at the University of Akron are discussed in this work along with a brief description of the HT-VARTM processing carried out at NASA-LaRC. Photomicrographs of the panels were taken and void contents were determined by acid digestion. Mechanical properties (short beam shear, SBS) of the panels fabricated by both infusion processes were determined at room temperature as well as at various elevated temperatures. The results of this work are presented herein.

Processing and Characterization of PETI Composites Fabricated by High Temperature VARTM

NASA Technical Reports Server (NTRS)

Ghose, Sayata; Cano, Roberto J.; Watson, Kent A.; Britton, Sean M.; Jensen, Brian J.; Connell, John W.; Smith, Joseph G.; Loos, Alfred C.; Heider, Dirk

2011-01-01

The use of composites as primary structures on aerospace vehicles has increased dramatically over the past decade. As these advanced structures increase in size and complexity, their production costs have grown significantly. A major contributor to these manufacturing costs is the requirement of elevated processing pressures, during the thermal cure, to create fully consolidated composites. For certain composite parts, high temperature vacuum assisted resin transfer molding (HT-VARTM) can offer reduced fabrication costs compared to conventional autoclave techniques. The process has been successfully used with phenylethynyl terminated imide (PETI) resins developed by NASA LaRC. In the current study, two PETI resins, LARC(TradeMark) PETI-330 and LARC(TradeMark) PETI-8 have been used to make test specimens using HT-VARTM. Based on previous work at NASA LaRC, larger panels with a quasi-isotropic lay-up were fabricated. The resultant composite specimens exhibited void contents <3% by volume depending on the type of carbon fabric preform used. Mechanical properties of the panels were determined at both room and elevated temperatures. These included open-hole compressive (OHC) and short beam shear (SBS) properties. Limited process modeling efforts were carried out including infusion times, composite panel size limitations and fabric permeability characterization. Work has also been carried out to develop new PETI based resins specifically geared towards HT-VARTM. The results of this work are presented herein.

Rapid fabrication of a micro-ball lens array by extrusion for optical fiber applications.

PubMed

Shen, S C; Huang, J C

2009-07-20

Batch-fabrication of a micro-ball lens array (MBA) could not only reduce micro assembly costs but also replace conventional ball lenses or costly GRINs (Gradient Refractive Index) without compromising performance. Compared with conventional half-spherical micro-lenses, the MBA is a spherical micro-lens that can focus light in all directions, thus providing the flexibility required for optical applications. Current MBAs are made of SU-8 photoresist by an extrusion process rather than the traditional thermal reflow process. The aim of this study was to develop a new process for MBA batch-fabrication, performed at ambient temperature, by spin-coating SU-8 onto a silicon-wafer surface, which serves as an extrusion plate, and extruding it through a nozzle to form an MBA. The nozzle consists of a nozzle orifice and nozzle cavity, the former being defined and made from SU-8 photoresist using ultra-violet (UV) lithography, which results in good mechanical properties. In this paper, the fabrication of 4 x 4 MBAs with diameters ranging from 60 to 550 um is described. Optical measurements indicated a diameter variance within 3% and a maximum coupling efficiency of approximately 62% when the single mode fiber (SMF) was placed at a distance of 10 um from the MBA. The results of this study proved that MBA fabrication by the extrusion process can enhance the coupling efficiency.

Influence of multiple-passes on microstructure and mechanical properties of Al-Mg/SiC surface composites fabricated via underwater friction stir processing

NASA Astrophysics Data System (ADS)

Srivastava, Manu; Rathee, Sandeep; Maheshwari, Sachin; Siddiquee, Arshad Noor

2018-06-01

Friction stir processing (FSP) is a relatively newly developed solid-state process involving surface modifications for fabricating metal matrix surface composites. Obtaining metal matrix nano-composites with uniform dispersion of reinforcement particles via FSP route is an intricate task to accomplish. In this work, AA5059/SiC nano surface composites (SCs) were developed. Effect of multiple FSP passes and SiC addition on microstructure and mechanical properties of fabricated SCs during underwater condition was investigated. Results reflected that the average microhardness value of base metal (BM) increases from 85 Hv to 159 Hv in stir zone of four pass underwater friction stir processed (FSPed) SC. Highest ultimate tensile strength (UTS) achieved during four pass FSPed sample was 377 MPa that is higher than UTS of BM (321 MPa) and four pass FSPed sample developed at ambient air FSP conditions (347 MPa). An appreciably narrower heat affected zone is obtained owing to fast cooling and reduced heat conduction during underwater FSP, amounting to higher UTS as compared to BM and SC at ambient conditions. Thus, it can be concluded that surrounding medium and number of FSP passes have significant impact on mechanical properties of fabricated SCs. Analysis of microstructures and distribution of SiC particles in fabricated SCs were studied by optical microscope and FESEM respectively and found in good corroboration with the mechanical properties.

Computer-Aided Process Model For Carbon/Phenolic Materials

NASA Technical Reports Server (NTRS)

Letson, Mischell A.; Bunker, Robert C.

1996-01-01

Computer program implements thermochemical model of processing of carbon-fiber/phenolic-matrix composite materials into molded parts of various sizes and shapes. Directed toward improving fabrication of rocket-engine-nozzle parts, also used to optimize fabrication of other structural components, and material-property parameters changed to apply to other materials. Reduces costs by reducing amount of laboratory trial and error needed to optimize curing processes and to predict properties of cured parts.

Screening of high temperature adhesives for large area bonding

NASA Technical Reports Server (NTRS)

Stenersen, A. A.; Wykes, D. H.

1980-01-01

High temperature-resistant adhesive systems were screened for processability, mechanical and physical properties, operational capability at 589 K (600 F), and the ability to produce large area bonds of high quality in fabricating Space Shuttle components. The adhesives consisted primarily of polyimide systems, including FM34B-18, NR-150B2 (DuPont), PMR-15, LARC-13, LARC-160, Thermid 600, and AI-1130L (AMOCA). The processing studies included preparation of polyimide resins, fabrication of film adhesives, development of lay-up and cure procedures, fabrication of honeycomb sandwich panels, and fabrication of mid-plane bonded panels in joints up to 30.5 cm (12 in.) wide. The screening program included tests for tack and drape properties, reticulation and filleting characteristics, ability to produce void-free or low porosity bonds in mid-plane bonded panels, out-time stability, lap shear strength, climbing drum peel strength, and glass transition temperature (Tg). This paper describes the processing methods developed and the test results.

Design Application Translates 2-D Graphics to 3-D Surfaces

NASA Technical Reports Server (NTRS)

2007-01-01

Fabric Images Inc., specializing in the printing and manufacturing of fabric tension architecture for the retail, museum, and exhibit/tradeshow communities, designed software to translate 2-D graphics for 3-D surfaces prior to print production. Fabric Images' fabric-flattening design process models a 3-D surface based on computer-aided design (CAD) specifications. The surface geometry of the model is used to form a 2-D template, similar to a flattening process developed by NASA's Glenn Research Center. This template or pattern is then applied in the development of a 2-D graphic layout. Benefits of this process include 11.5 percent time savings per project, less material wasted, and the ability to improve upon graphic techniques and offer new design services. Partners include Exhibitgroup/Giltspur (end-user client: TAC Air, a division of Truman Arnold Companies Inc.), Jack Morton Worldwide (end-user client: Nickelodeon), as well as 3D Exhibits Inc., and MG Design Associates Corp.

Femtosecond Laser Fabrication of Monolithically Integrated Microfluidic Sensors in Glass

PubMed Central

He, Fei; Liao, Yang; Lin, Jintian; Song, Jiangxin; Qiao, Lingling; Cheng, Ya; Sugioka, Koji

2014-01-01

Femtosecond lasers have revolutionized the processing of materials, since their ultrashort pulse width and extremely high peak intensity allows high-quality micro- and nanofabrication of three-dimensional (3D) structures. This unique capability opens up a new route for fabrication of microfluidic sensors for biochemical applications. The present paper presents a comprehensive review of recent advancements in femtosecond laser processing of glass for a variety of microfluidic sensor applications. These include 3D integration of micro-/nanofluidic, optofluidic, electrofluidic, surface-enhanced Raman-scattering devices, in addition to fabrication of devices for microfluidic bioassays and lab-on-fiber sensors. This paper describes the unique characteristics of femtosecond laser processing and the basic concepts involved in femtosecond laser direct writing. Advanced spatiotemporal beam shaping methods are also discussed. Typical examples of microfluidic sensors fabricated using femtosecond lasers are then highlighted, and their applications in chemical and biological sensing are described. Finally, a summary of the technology is given and the outlook for further developments in this field is considered. PMID:25330047

Design and fabrication of self-assembled thin films

NASA Astrophysics Data System (ADS)

Topasna, Daniela M.; Topasna, Gregory A.

2015-10-01

Students experience the entire process of designing, fabricating and testing thin films during their capstone course. The films are fabricated by the ionic-self assembled monolayer (ISAM) technique, which is suited to a short class and is relatively rapid, inexpensive and environmentally friendly. The materials used are polymers, nanoparticles, and small organic molecules that, in various combinations, can create films with nanometer thickness and with specific properties. These films have various potential applications such as pH optical sensors or antibacterial coatings. This type of project offers students an opportunity to go beyond the standard lecture and labs and to experience firsthand the design and fabrication processes. They learn new techniques and procedures, as well as familiarize themselves with new instruments and optical equipment. For example, students learn how to characterize the films by using UV-Vis-NIR spectrophotometry and in the process learn how the instruments operate. This work compliments a previous exercise that we introduced where students use MATHCAD to numerically model the transmission and reflection of light from thin films.

Investigation of mechanical properties for open cellular structure CoCrMo alloy fabricated by selective laser melting process

NASA Astrophysics Data System (ADS)

Azidin, A.; Taib, Z. A. M.; Harun, W. S. W.; Che Ghani, S. A.; Faisae, M. F.; Omar, M. A.; Ramli, H.

2015-12-01

Orthodontic implants have been a major focus through mechanical and biological performance in advance to fabricate shape of complex anatomical. Designing the part with a complex mechanism is one of the challenging process and addition to achieve the balance and desired mechanical performance brought to the right manufacture technique to fabricate. Metal additive manufacturing (MAM) is brought forward to the newest fabrication technology in this field. In this study, selective laser melting (SLM) process was utilized on a medical grade cobalt-chrome molybdenum (CoCrMo) alloy. The work has focused on mechanical properties of the CoCrMo open cellular structures samples with 60%, 70%, and 80% designed volume porosity that could potentially emulate the properties of human bone. It was observed that hardness values decreased as the soaking time increases except for bottom face. For compression test, 60% designed volume porosity demonstrated highest ultimate compressive strength compared to 70% and 80%.

Reliable fabrication of plasmonic nanostructures without an adhesion layer using dry lift-off

NASA Astrophysics Data System (ADS)

Chen, Yiqin; Li, Zhiqin; Xiang, Quan; Wang, Yasi; Zhang, Zhiqiang; Duan, Huigao

2015-10-01

Lift-off is the most commonly used pattern-transfer method to define lithographic plasmonic metal nanostructures. A typical lift-off process is realized by dissolving patterned resists in solutions, which has the limits of low yield when not using adhesion layers and incompatibility with the fabrication of some specific structures and devices. In this work, we report an alternative ‘dry’ lift-off process to obtain metallic nanostructures via mechanical stripping by using the advantage of poor adhesion between resists and noble metal films. We show that this dry stripping lift-off method is effective for both positive- and negative-tone resists to fabricate sparse and densely-packed plasmonic nanostructures, respectively. In particular, this method is achieved without using an adhesion layer, which enables the mitigation of plasmon damping to obtain larger field enhancement. Dark-field scattering, one-photon luminescence and surface-enhanced Raman scattering measurements were performed to demonstrate the improved quality factor of the plasmonic nanostructures fabricated by this dry lift-off process.

Solution processed flexible organic thin film back-gated transistors based on polyimide dielectric films

NASA Astrophysics Data System (ADS)

Park, Janghoon; Min, Yoonki; Lee, Dongjin

2018-04-01

An organic thin film back-gated transistor (OBGT) was fabricated and characterized. The gate electrode was printed on the back side of substrate, and the dielectric layer was omitted by substituting the dielectric layer with the polyimide (PI) film substrate. Roll-to-roll (R2R) gravure printing, doctor blading, and drop casting methods were used to fabricate the OBGT. The printed OBGT device shows better performance compared with an OTFT device based on dielectric layer of BaTiO3. Additionally, a calendering process enhanced the performance by a factor of 3 to 7 (mobility: 0.016 cm2/V.s, on/off ratio: 9.17×103). A bending test was conducted to confirm the flexibility and durability of the OBGT device. The results show the fabricated device endures 20000-cyclic motions. The realized OBGT device was successfully fabricated and working, which is meaningful for production engineering from the viewpoint of process development.

3D printed electromagnetic transmission and electronic structures fabricated on a single platform using advanced process integration techniques

NASA Astrophysics Data System (ADS)

Deffenbaugh, Paul Issac

3D printing has garnered immense attention from many fields including in-office rapid prototyping of mechanical parts, outer-space satellite replication, garage functional firearm manufacture, and NASA rocket engine component fabrication. 3D printing allows increased design flexibility in the fabrication of electronics, microwave circuits and wireless antennas and has reached a level of maturity which allows functional parts to be printed. Much more work is necessary in order to perfect the processes of 3D printed electronics especially in the area of automation. Chapter 1 shows several finished prototypes of 3D printed electronics as well as newly developed techniques in fabrication. Little is known about the RF and microwave properties and applications of the standard materials which have been developed for 3D printing. Measurement of a wide variety of materials over a broad spectrum of frequencies up to 10 GHz using a variety of well-established measurement methods is performed throughout chapter 2. Several types of high frequency RF transmission lines are fabricated and valuable model-matched data is gathered and provided in chapter 3 for future designers' use. Of particular note is a fully 3D printed stripline which was automatically fabricated in one process on one machine. Some core advantages of 3D printing RF/microwave components include rapid manufacturing of complex, dimensionally sensitive circuits (such as antennas and filters which are often iteratively tuned) and the ability to create new devices that cannot be made using standard fabrication techniques. Chapter 4 describes an exemplary fully 3D printed curved inverted-F antenna.

Process for manufacturing multilayer capacitors

DOEpatents

Lauf, R.J.; Holcombe, C.E.; Dykes, N.L.

1996-01-02

The invention is directed to a method of manufacture of multilayer electrical components, especially capacitors, and components made by such a method. High capacitance dielectric materials and low cost metallizations layered with such dielectrics may be fabricated as multilayer electrical components by sintering the metallizations and the dielectrics during the fabrication process by application of microwave radiation. 4 figs.

In-space fabrication of thin-film structures

NASA Technical Reports Server (NTRS)

Lippman, M. E.

1972-01-01

A conceptual study of physical vapor-deposition processes for in-space fabrication of thin-film structures is presented. Potential advantages of in-space fabrication are improved structural integrity and surface reflectivity of free-standing ultra-thin films and coatings. Free-standing thin-film structures can find use as photon propulsion devices (solar sails). Other applications of the concept involve free-standing shadow shields, or thermal control coatings of spacecraft surfaces. Use of expendables (such as booster and interstage structures) as source material for the physical vapor deposition process is considered. The practicability of producing thin, textured, aluminum films by physical vapor deposition and subsequent separation from a revolving substrate is demonstrated by laboratory experiments. Heating power requirement for the evaporation process is estimated for a specific mission.

Fabrication of nano-scale Cu bond pads with seal design in 3D integration applications.

PubMed

Chen, K N; Tsang, C K; Wu, W W; Lee, S H; Lu, J Q

2011-04-01

A method to fabricate nano-scale Cu bond pads for improving bonding quality in 3D integration applications is reported. The effect of Cu bonding quality on inter-level via structural reliability for 3D integration applications is investigated. We developed a Cu nano-scale-height bond pad structure and fabrication process for improved bonding quality by recessing oxides using a combination of SiO2 CMP process and dilute HF wet etching. In addition, in order to achieve improved wafer-level bonding, we introduced a seal design concept that prevents corrosion and provides extra mechanical support. Demonstrations of these concepts and processes provide the feasibility of reliable nano-scale 3D integration applications.

Fabrication of boron sputter targets

DOEpatents

Makowiecki, D.M.; McKernan, M.A.

1995-02-28

A process is disclosed for fabricating high density boron sputtering targets with sufficient mechanical strength to function reliably at typical magnetron sputtering power densities and at normal process parameters. The process involves the fabrication of a high density boron monolithe by hot isostatically compacting high purity (99.9%) boron powder, machining the boron monolithe into the final dimensions, and brazing the finished boron piece to a matching boron carbide (B{sub 4}C) piece, by placing aluminum foil there between and applying pressure and heat in a vacuum. An alternative is the application of aluminum metallization to the back of the boron monolithe by vacuum deposition. Also, a titanium based vacuum braze alloy can be used in place of the aluminum foil. 7 figs.

Technology Development for Nickel X-Ray Optics Enhancement

NASA Technical Reports Server (NTRS)

Bubarev, Mikhail; Ramsey, Brian; Engelhaupt, Darell

2008-01-01

We are developing grazing-incidence x-ray optics for high-energy astrophysics using the electroform-nickel replication process. In this process, mirror shells are fabricated by replication off super-polished cylindrical mandrels. The mirrors fabricated using this process have a demonstrated optical performance at the level of 11-12 arc seconds resolution (HPD) for 30 keV x rays. Future missions demand ever higher angular resolutions and this places stringent requirements on the quality of the mandrels, the precision of the metrology, and the mounting and alignment of the mirror shells in their housings. A progress report on recent technology developments in all these areas will be presented along with a discussion on possible post fabrication, in-situ improvement of the x-ray mirrors quality.

Direct writing of metal nanostructures: lithographic tools for nanoplasmonics research.

PubMed

Leggett, Graham J

2011-03-22

Continued progress in the fast-growing field of nanoplasmonics will require the development of new methods for the fabrication of metal nanostructures. Optical lithography provides a continually expanding tool box. Two-photon processes, as demonstrated by Shukla et al. (doi: 10.1021/nn103015g), enable the fabrication of gold nanostructures encapsulated in dielectric material in a simple, direct process and offer the prospect of three-dimensional fabrication. At higher resolution, scanning probe techniques enable nanoparticle particle placement by localized oxidation, and near-field sintering of nanoparticulate films enables direct writing of nanowires. Direct laser "printing" of single gold nanoparticles offers a remarkable capability for the controlled fabrication of model structures for fundamental studies, particle-by-particle. Optical methods continue to provide a powerful support for research into metamaterials.

Cost-effective MEMS piezoresistive cantilever-based sensor fabrication for gait movement analysis

NASA Astrophysics Data System (ADS)

Saadon, Salem; Anuar, A. F. M.; Wahab, Yufridin

2017-03-01

The conventional photolithography of crystalline silicon technique is limited to two-dimensional and structure scaling. It's also requiring a lot of time and chemical involves for the whole process. These problems can be overcome by using laser micromachining technique, that capable to produce three-dimensional structure and simultaneously avoiding the photo mask needs. In this paper, we reported on the RapidX-250 Excimer laser micromachining with 248 nm KrF to create in-time mask design and assisting in the fabrication process of piezo-resistive micro cantilever structures. Firstly, laser micromachining parameters have been investigated in order to fabricate the acceleration sensor to analyzing human gait movement. Preliminary result shows that the fabricated sensor able to define the movement difference of human motion regarding the electrical characteristic of piezo-resistor.

Chemical free device fabrication of two dimensional van der Waals materials based transistors by using one-off stamping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Young Tack, E-mail: 023273@kist.re.kr, E-mail: stunalren@gmail.com; Choi, Won Kook; Materials and Life Science Research Division, Korea Institute of Science and Technology

We report on a chemical free one-off imprinting method to fabricate two dimensional (2D) van der Waals (vdWs) materials based transistors. Such one-off imprinting technique is the simplest and effective way to prevent unintentional chemical reaction or damage of 2D vdWs active channel during device fabrication process. 2D MoS{sub 2} nanosheets based transistors with a hexagonal-boron-nitride (h-BN) passivation layer, prepared by one-off imprinting, show negligible variations of transfer characteristics after chemical vapor deposition process. In addition, this method enables the fabrication of all 2D MoS{sub 2} transistors consisting of h-BN gate insulator, and graphene source/drain and gate electrodes without anymore » chemical damage.« less

In Situ Fabrication Technologies: Meeting the Challenge for Exploration

NASA Technical Reports Server (NTRS)

Howard, Richard W.

2005-01-01

A viewgraph presentation on Lunar and Martian in situ fabrication technologies meeting the challenges for exploration is shown. The topics include: 1) Exploration Vision; 2) Vision Requirements Early in the Program; 3) Vision Requirements Today; 4) Why is ISFR Technology Needed? 5) ISFR and In Situ Resource Utilization (ISRU); 6) Fabrication Feedstock Considerations; 7) Planetary Resource Primer; 8) Average Chemical Element Abundances in Lunar Soil; 9) Chemical Elements in Aerospace Engineering Materials; 10) Schematic of Raw Regolith Processing into Constituent Components; 11) Iron, Aluminum, and Basalt Processing from Separated Elements and Compounds; 12) Space Power Systems; 13) Power Source Applicability; 14) Fabrication Systems Technologies; 15) Repair and Nondestructive Evaluation (NDE); and 16) Habitat Structures. A development overview of Lunar and Martian repair and nondestructive evaluation is also presented.

Effect of Orientation on Tensile Properties of Inconel 718 Block Fabricated with Electron Beam Freeform Fabrication (EBF3)

NASA Technical Reports Server (NTRS)

Bird, R. Keith; Atherton, Todd S.

2010-01-01

Electron beam freeform fabrication (EBF3) direct metal deposition processing was used to fabricate an Inconel 718 bulk block deposit. Room temperature tensile properties were measured as a function of orientation and location within the block build. This study is a follow-on activity to previous work on Inconel 718 EBF3 deposits that were too narrow to allow properties to be measured in more than one orientation

Fabrication and testing of fire resistant graphite composite panels

NASA Technical Reports Server (NTRS)

Roper, W. D.

1986-01-01

Eight different graphite composite panels were fabricated using four different resin matrices. The resin matrices included Hercules 71775, a blend of vinylpolystyrpyridine and bismaleimide, H795, a bismaleimide, Cycom 6162, a phenolic, and PSP 6022m, a polystyrylpyridine. Graphite panels were fabricated using fabric or unidirectional tape. Described are the processes for preparing these panels and some of their mechanical, thermal and flammability properties. Panel properties are compared with state-of-the-art epoxy fiberglass composite panels.

Single-step fabrication of electrodes with controlled nanostructured surface roughness using optically-induced electrodeposition

NASA Astrophysics Data System (ADS)

Liu, N.; Li, M.; Liu, L.; Yang, Y.; Mai, J.; Pu, H.; Sun, Y.; Li, W. J.

2018-02-01

The customized fabrication of microelectrodes from gold nanoparticles (AuNPs) has attracted much attention due to their numerous applications in chemistry and biomedical engineering, such as for surface-enhanced Raman spectroscopy (SERS) and as catalyst sites for electrochemistry. Herein, we present a novel optically-induced electrodeposition (OED) method for rapidly fabricating gold electrodes which are also surface-modified with nanoparticles in one single step. The electrodeposition mechanism, with respect to the applied AC voltage signal and the elapsed deposition time, on the resulting morphology and particle sizes was investigated. The results from SEM and AFM analysis demonstrated that 80-200 nm gold particles can be formed on the surface of the gold electrodes. Simultaneously, both the size of the nanoparticles and the roughness of the fabricated electrodes can be regulated by the deposition time. Compared to state-of-the-art methods for fabricating microelectrodes with AuNPs, such as nano-seed-mediated growth and conventional electrodeposition, this OED technique has several advantages including: (1) electrode fabrication and surface modification using nanoparticles are completed in a single step, eliminating the need for prefabricating micro electrodes; (2) the patterning of electrodes is defined using a digitally-customized, projected optical image rather than using fixed physical masks; and (3) both the fabrication and surface modification processes are rapid, and the entire fabrication process only requires less than 6 s.

Fabrication of three-dimensional millimeter-height structures using direct ultraviolet lithography on liquid-state photoresist for simple and fast manufacturing

NASA Astrophysics Data System (ADS)

Kim, Jungkwun; Yoon, Yong-Kyu

2015-07-01

A rapid three-dimensional (3-D) ultraviolet (UV) lithography process for the fabrication of millimeter-tall high aspect ratio complex structures is presented. The liquid-state negative-tone photosensitive polyurethane, LF55GN, has been directly photopatterned using multidirectionally projected UV light for 3-D micropattern formation. The proposed lithographic scheme enabled us to overcome the maximum height obtained with a photopatternable epoxy, SU8, which has been conventionally most commonly used for the fabrication of tall and high aspect ratio microstructures. Also, the fabrication process time has been significantly reduced by eliminating photoresist-baking steps. Computer-controlled multidirectional UV lithography has been employed to fabricate 3-D structures, where the UV-exposure substrate is dynamically tilt-rotating during UV exposure to create various 3-D ray traces in the polyurethane layer. LF55GN has been characterized to provide feasible fabrication conditions for the multidirectional UV lithography. Very tall structures including a 6-mm tall triangular slab and a 5-mm tall hexablaze have been successfully fabricated. A 4.5-mm tall air-lifted polymer-core bowtie monopole antenna, which is the tallest monopole structure fabricated by photolithography and subsequent metallization, has been successfully demonstrated. The antenna shows a resonant radiation frequency of 12.34 GHz, a return loss of 36 dB, and a 10 dB bandwidth of 7%.

3D Nanofabrication Using AFM-Based Ultrasonic Vibration Assisted Nanomachining

NASA Astrophysics Data System (ADS)

Deng, Jia

Nanolithography and nanofabrication processes have significant impact on the recent development of fundamental research areas such as physics, chemistry and biology, as well as the modern electronic devices that have reached nanoscale domain such as optoelectronic devices. Many advanced nanofabrication techniques have been developed and reported to satisfy different requirements in both research areas and applications such as electron-beam lithography. However, it is expensive to use and maintain the equipment. Atomic Force Microscope (AFM) based nanolithography processes provide an alternative approach to nanopatterning with significantly lower cost. Recently, three dimensional nanostructures have attracted a lot of attention, motivated by many applications in various fields including optics, plasmonics and nanoelectromechanical systems. AFM nanolithography processes are able to create not only two dimensional nanopatterns but also have the great potential to fabricate three dimensional nanostructures. The objectives of this research proposal are to investigate the capability of AFM-based three dimensional nanofabrication processes, to transfer the three dimensional nanostructures from resists to silicon surfaces and to use the three dimensional nanostructures on silicon in applications. Based on the understanding of literature, a novel AFM-based ultrasonic vibration assisted nanomachining system is utilized to develop three dimensional nanofabrication processes. In the system, high-frequency in plane circular xy-vibration was introduced to create a virtual tool, whose diameter is controlled by the amplitude of xy-vibration and is larger than that of a regular AFM tip. Therefore, the feature width of a single trench is tunable. Ultrasonic vibration of sample in z-direction was introduced to control the depth of single trenches, creating a high-rate 3D nanomachining process. Complicated 3D nanostructures on PMMA are fabricated under both the setpoint force and z-height control modes. Complex contours and both discrete and continuous height changes are able to be fabricated by the novel 3D nanofabrication processes. Results are imaged clearly after cleaning the debris covering on the 3D nanostructures after nanomachining process. The process is validated by fabricating various 3D nanostructures. The advantages and disadvantages are compared between these two control modes. Furthermore, the 3D nanostructures were further transferred from PMMA surfaces onto silicon surfaces using reactive ion etching (RIE) process. Recipes are developed based on the functionality of the etching gas in the transfer process. Tunable selectivity and controllable surface finishes are achieved by varying the flow rate of oxygen. The developed 3D nanofabrication process is used as a novel technique in two applications, master fabrication for soft lithography and SERS substrates fabrication. 3D nanostructures were reversely molded on PDMS and then duplicated on new PMMA substrates. 3D nanostructures are fabricated, which can be either directly used or transferred on silicon as SERS substrates after coating 80 nm gold layers. They greatly enhanced the intensity of Raman scattering with the enhancement factor of 3.11x103. These applications demonstrate the capability of the novel process of AFM-based 3D nanomachining.

Fabrication of Natural Uranium UO 2 Disks (Phase II): Texas A&M Work for Others Summary Document

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gerczak, Tyler J.; Baldwin, Charles A.; Schmidlin, Joshua E.

The steps to fabricate natural UO 2 disks for an irradiation campaign led by Texas A&M University are outlined. The process was initiated with stoichiometry adjustment of parent, U 3O 8 powder. The next stage of sample preparation involved exploratory pellet pressing and sintering to achieve the desired natural UO 2 pellet densities. Ideal densities were achieved through the use of a bimodal powder size blend. The steps involved with disk fabrication are also presented, describing the coring and thinning process executed to achieve final dimensionality.

Measuring the In-Process Figure, Final Prescription, and System Alignment of Large Optics and Segmented Mirrors Using Lidar Metrology

NASA Technical Reports Server (NTRS)

Ohl, Raymond; Slotwinski, Anthony; Eegholm, Bente; Saif, Babak

2011-01-01

The fabrication of large optics is traditionally a slow process, and fabrication capability is often limited by measurement capability. W hile techniques exist to measure mirror figure with nanometer precis ion, measurements of large-mirror prescription are typically limited to submillimeter accuracy. Using a lidar instrument enables one to measure the optical surface rough figure and prescription in virtuall y all phases of fabrication without moving the mirror from its polis hing setup. This technology improves the uncertainty of mirror presc ription measurement to the micron-regime.

Silicon on insulator self-aligned transistors

DOEpatents

McCarthy, Anthony M.

2003-11-18

A method for fabricating thin-film single-crystal silicon-on-insulator (SOI) self-aligned transistors. Standard processing of silicon substrates is used to fabricate the transistors. Physical spaces, between the source and gate, and the drain and gate, introduced by etching the polysilicon gate material, are used to provide connecting implants (bridges) which allow the transistor to perform normally. After completion of the silicon substrate processing, the silicon wafer is bonded to an insulator (glass) substrate, and the silicon substrate is removed leaving the transistors on the insulator (glass) substrate. Transistors fabricated by this method may be utilized, for example, in flat panel displays, etc.

Electron Beam Freeform Fabrication: A Fabrication Process that Revolutionizes Aircraft Structural Designs and Spacecraft Supportability

NASA Technical Reports Server (NTRS)

Taminger, Karen M.

2008-01-01

The technological inception and challenges, as well as current applications of the electron beam freeform fabrication (EBF3) process are outlined. The process was motivated by the need for a new metals technology that would be cost-effective, enable the production of new alloys and that would could be used for efficient, lightweight structures. EBF3 is a rapid metal fabrication, layer-additive process that uses no molds or tools and which yields properties equivalent to wrought. The benefits of EBF3 include it near-net shape which minimizes scrap and reduces part count; efficiency in design which allows for lighter weight and enhanced performance; and, its "green" manufacturing process which yields minimal waste products. EBF3 also has a high tensile strength, while a structural test comparison found that EBF3 panels performed 5% lower than machined panels. Technical challenges in the EBF3 process include a need for process control monitoring and an improvement in localized heat response. Currently, the EBF3 process can be used to add details onto forgings and to construct and form complex shapes. However, it has potential uses in a variety of industries including aerospace, automotive, sporting goods and medical implant devices. The novel structural design capabilities of EBF3 have the ability to yield curved stiffeners which may be optimized for performance, low weight, low noise and damage tolerance applications. EBF3 has also demonstrated its usefulness in 0-gravity environments for supportability in space applications.