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Washburn, Cody M.

Publications and source records attributed to Washburn, Cody M..

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Additive manufacturing print-heads for exotic material applications

Described herein is an additive manufacturing apparatus that is well-suited for constructing piezoelectric sensors. The additive manufacturing apparatus includes an extrusion nozzle formed of a conductive material such as aluminum. The extrusion nozzle has a channel by way of which printing material exits the extrusion nozzle, wherein a build plate is configured to receive the printing material responsive to the printing material exiting the extrusion nozzle. An arc suppressor formed of a semiconductor is coupled to the extrusion nozzle and is configured to dissipate excess charge that would otherwise exist on the extrusion nozzle when a relatively high bias voltage is applied to the extrusion nozzle. Thus, the arc suppressor mitigates arcing between the extrusion nozzle and the build plate. Arc suppressing gas is also optionally introduced into a printing region, thereby further mitigating arcing between the extrusion nozzle and the build plate.

Washburn, Cody M.↗
DOE OSTI2020

Fabrication of multilayered carbon MEMS devices

The various technologies presented herein relate to formation of carbon micromechanical systems (CMEMS), wherein the CMEMS comprise multiple layers of carbon structures and are formed using a plurality of photoresist precursors that are processed to form carbon. The various embodiments can be utilized in producing a plurality of CMEMS with full production level fabrication, e.g., 6 inch wafers can be processed. A pyrolyzed layer of carbon is lithographically defined after pyrolysis, wherein the post-pyrolysis etch process can produce carbon structures having repeatable and accurate device geometries, with straight sidewalls. A sacrificial layer can be applied to facilitate separation of a first carbon layer from a second carbon layer, wherein, upon pyrolysis to form the second carbon layer and lithography thereof, the sacrificial layer is removed to form a CMEMS comprising a first carbon layer (e.g., comprising bottom contacts) located beneath a second carbon layer (e.g., a mechanical layer).

36 MATERIALS SCIENCE↗
DOE OSTI2019

Depolymerization of Cross-Linked Polybutadiene Networks in Situ Using Latent Alkene Metathesis

We report a novel approach whereby cross-linked polybutadiene (PB) networks can be depolymerized in situ based on thermally activated alkene metathesis. A commercially available latent Ru catalyst, HeatMet, was compared to the common second-generation Hoveyda–Grubbs catalyst, HG2, in the metathetic depolymerization of PB. HeatMet was found to possess exceptional stability and negligible activity toward PB under ambient conditions, in solution and in bulk. This enabled cross-linked networks to be prepared containing homogeneously distributed Ru catalyst. The dynamic mechanical properties of networks containing HeatMet and cross-linked using alcohol–isocyanate or thiol–ene chemistry were evaluated during cross-linking and post-cross-linking under isothermal and nonisothermal heating. In both cases, above minimum catalyst loadings ranging from 0.004 to 0.024 mol %, the networks exhibited rapid degelation into a soluble oil upon heating to 100 °C. At these temperatures, extensive depolymerization of the PB segments through ring-closing metathesis of 1,4/1,2 diads by the activated HeatMet introduced network defects in significantly greater proportion than the original number of cross-links. The in situ depolymerization of cross-linked PB networks through latent catalysis, as described here, may enable facile disposal and recycling of PB encapsulants and adhesives, among other applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Graphene heat dissipating structure

Various technologies presented herein relate to forming one or more heat dissipating structures (e.g., heat spreaders and/or heat sinks) on a substrate, wherein the substrate forms part of an electronic component. The heat dissipating structures are formed from graphene, with advantage being taken of the high thermal conductivity of graphene. The graphene (e.g., in flake form) is attached to a diazonium molecule, and further, the diazonium molecule is utilized to attach the graphene to material forming the substrate. A surface of the substrate is treated to comprise oxide-containing regions and also oxide-free regions having underlying silicon exposed. The diazonium molecule attaches to the oxide-free regions, wherein the diazonium molecule bonds (e.g., covalently) to the exposed silicon. Attachment of the diazonium plus graphene molecule is optionally repeated to enable formation of a heat dissipating structure of a required height.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Graphene heat dissipating structure

Various technologies presented herein relate to forming one or more heat dissipating structures (e.g., heat spreaders and/or heat sinks) on a substrate, wherein the substrate forms part of an electronic component. The heat dissipating structures are formed from graphene, with advantage being taken of the high thermal conductivity of graphene. The graphene (e.g., in flake form) is attached to a diazonium molecule, and further, the diazonium molecule is utilized to attach the graphene to material forming the substrate. A surface of the substrate is treated to comprise oxide-containing regions and also oxide-free regions having underlying silicon exposed. The diazonium molecule attaches to the oxide-free regions, wherein the diazonium molecule bonds (e.g., covalently) to the exposed silicon. Attachment of the diazonium plus graphene molecule is optionally repeated to enable formation of a heat dissipating structure of a required height.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Lithographically defined microporous carbon-composite structures

A microporous carbon scaffold is produced by lithographically patterning a carbon-containing photoresist, followed by pyrolysis of the developed resist structure. Prior to exposure, the photoresist is loaded with a nanoparticulate material. After pyrolysis, the nanonparticulate material is dispersed in, and intimately mixed with, the carbonaceous material of the scaffold, thereby yielding a carbon composite structure.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Carbon Composite Microelectromechanical Systems (CMEMS)

Pyrolyzed carbon as a mechanical material is promising for applications in harsh environments. In this work, we characterized the material and developed novel processes for fabricating carbon composite micro-electromechanical systems (CMEMS) structures. A novel method of increasing Young's modulus and the conductivity of pyrolyzed AZ 4330 was demonstrated by loading the films with graphene oxide prior to pyrolysis. By incorporating 2 wt.% graphene stiffeners into the film, a 65% increase in Young's modulus and 11% increase in conductivity were achieved. By reactive ion etching pyrolyzed blanket AZ 50XT thick film photoresist, a high aspect ratio process was demonstrated with films >7.5um thick. Two novel multi-level, volume-scalable CMEMS processes were developed on 6" diameter wafers. Young's modulus of 23 GPa was extracted from nanoindentation measurements of pyrolyzed AZ 50XT films. The temperature-dependent resistance was characterized from room temperature to 500C and found to be nearly linear over this range. By fitting the results of self-heated bridges in an inert ambient, we calculated that the bridges survived to 1000C without failure. Transmission electron microscopy (TEM) results showed the film to be largely amorphous, containing some sub-micrometer sized graphite crystallites. This was consistent with our Raman analysis, which also showed the film to be largely sp 2 bonded. The calculated average density of pyrolyzed AZ 4330 films was 1.32 g/cm 2 . Thin level of disorder and the conductivity of thin film resistors were found to unchanged by 2Mrad gamma irradiation from a Co 60 source. Thin film pyrolyzed carbon resistors were hermetically sealed in a nitrogen ambient in 24-pin dual in-line packages (DIP's). The resistance was measured periodically and remained constant over 6 months' time.

36 MATERIALS SCIENCE↗