Rapid Electrical Heating of Aluminum-Boron Nano-Laminates

MRS Advances ◽  
2018 ◽  
Vol 3 (17) ◽  
pp. 905-910
Author(s):  
David M. Lunking ◽  
David P. Adams ◽  
Christopher J. Morris
Keyword(s):  
Elevated Temperatures ◽  
Electrical Heating ◽  
Heat Of Mixing ◽  
Heat Of Reaction ◽  
Electrically Conductive ◽  
Electrical Insulator ◽  
Reactive Material ◽  
Conductive Films ◽  
Vaporization Temperature ◽  
Insight Into

ABSTRACTRapid or explosive heating of electrically conductive films has several applications, and the use of reactive laminates to increase output energy is an intriguing concept. Past studies have shown electrically heated aluminum/nickel (Al/Ni) nano-laminate films to augment this energy by an amount approximately equivalent to the expected heat of mixing between the two elements, which for most intermetallics is a significant fraction of the total heat of reaction (86% for Al/Ni). In this study, we investigate the use of sputtered aluminum/boron (Al/B) laminates to determine whether a similar increase, as measured by the velocity of an ejected flyer layer, occurs. However, observed velocities in any samples containing boron were 38% to 45% lower than samples without boron, despite much higher heats of reaction reported in the literature for Al/B. We attributed this reduction to the vaporization temperature of boron being much higher than that of Al, and because Al electrical resistivity at elevated temperatures was still much lower than boron, boron heating was less efficient as vaporized Al expanded and drove the ejected flyer. These results and analysis give insight into other reactive material combinations in which one of the constituents is an electrical insulator.

Facing extremes: archaeal surface-layer (glyco)proteins

Microbiology ◽  
2003 ◽  
Vol 149 (12) ◽  
pp. 3347-3351 ◽  
Author(s):  
Jerry Eichler
Keyword(s):  
Surface Layer ◽  
Structural Integrity ◽  
Elevated Temperatures ◽  
Protein Biosynthesis ◽  
Extreme Environments ◽  
Archaeal Protein ◽  
The Face ◽  
Micro Organisms ◽  
Physical Challenges ◽  
Insight Into

Archaea are best known in their capacities as extremophiles, i.e. micro-organisms able to thrive in some of the most drastic environments on Earth. The protein-based surface layer that envelopes many archaeal strains must thus correctly assemble and maintain its structural integrity in the face of the physical challenges associated with, for instance, life in high salinity, at elevated temperatures or in acidic surroundings. Study of archaeal surface-layer (glyco)proteins has thus offered insight into the strategies employed by these proteins to survive direct contact with extreme environments, yet has also served to elucidate other aspects of archaeal protein biosynthesis, including glycosylation, lipid modification and protein export. In this mini-review, recent advances in the study of archaeal surface-layer (glyco)proteins are discussed.

Modifiable Silicones for Harsh Environments

2011 ◽  
Vol 2011 (1) ◽  
pp. 000090-000098 ◽  
Author(s):  
Michelle Velderrain ◽  
Matthew Lindberg
Keyword(s):  
Elevated Temperatures ◽  
Electronic Devices ◽  
Polymeric Materials ◽  
Harsh Environments ◽  
Electrically Conductive ◽  
Polymeric Systems ◽  
Low Modulus ◽  
Conductive Fillers ◽  
Processing Techniques

Silicones have been used for decades in aerospace and other harsh environments where temperature extremes are common. As the level of sophistication increases for electronic devices to serve these industries where failure is not an option, the material supplier has to also be able to meet these needs. Silicones are polymeric materials composed primarily of repeating silicon and oxygen bonds, known as siloxanes, which can be optimized for various chemical and physical properties by incorporating different organic groups onto the silicon atom. Employing advanced processing techniques to the siloxane system can also greatly reduce mobile siloxane molecules to reduce contamination that can cause electronic failures during assembly or operation. Siloxane based polymeric systems are also unique polymers compared to standard organic based materials in that they have a large free volume that imparts a low modulus which absorbs stresses during thermal cycling as well as not degrading at continuous operating temperatures up to 250 C. They are also slightly polar which allows the incorporation of fillers to impart a variety of unique properties. Filler technology is also a rapidly growing enterprise where fillers with various particle sizes and shapes can be added to silicones to impart key properties such as maintaining electric conductivity at elevated temperatures. This paper will explain fundamentals of silicone chemistry and processing related to getting the optimal performance in harsh environments. A case study comparing two different electrically conductive fillers and how they can influence the electrical conductivity at elevated temperatures will be presented.

Two-Station Embossing Process for Rapid Fabrication of Polymer Microstructures

2005 ◽  
Author(s):  
Donggang Yao ◽  
Allen Y. Yi ◽  
Lei Li ◽  
Pratapkumar Nagarajan
Keyword(s):  
Thermal Cycling ◽  
Elevated Temperatures ◽  
Polymeric Materials ◽  
Large Mass ◽  
Hot Embossing ◽  
Electrical Heating ◽  
Thermal Mass ◽  
Mold Surface ◽  
Cycle Times ◽  
Rapid Thermal Cycling

The hot embossing technique is becoming an increasingly important alternative to silicon-and glass-based microfabrication technologies. The advantage of hot embossing can be mainly attributed to the versatile properties and mass production capability of polymeric materials. However, because of the use of a large mass in thermal cycling, hot embossing is subject to substantially longer cycle times than those in traditional thermoplastic molding processes.1 The longer dwell time at elevated temperatures could further result in degradation of the embossing polymer, especially for thermally sensitive polymers. The problem exacerbates when thick polymer substrates are used. To address this problem, rapid thermal cycling of the tool is needed. One method for rapid thermal cycling is to employ a low-thermal-mass multilayer mold with electrical heating elements installed right beneath the mold surface.2 This method, however, is complex in nature and may be prone to problems caused by mismatching of thermal and mechanical properties between different layers.

Electrically conductive polymer/rGO nanocomposite films at ambient temperature via miniemulsion polymerization using GO as surfactant

Nanoscale ◽  
2019 ◽  
Vol 11 (14) ◽  
pp. 6566-6570 ◽  
Author(s):  
Yasemin Fadil ◽  
Vipul Agarwal ◽  
Florent Jasinski ◽  
Stuart C. Thickett ◽  
Hideto Minami ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Conductive Polymer ◽  
Miniemulsion Polymerization ◽  
Polymer Nanoparticles ◽  
Nanocomposite Films ◽  
Electrically Conductive ◽  
Conductive Films

A facile method to synthesize colloidally stable polymer nanoparticles decorated with GO sheets via miniemulsion polymerization, which enables the preparation of electrically conductive films using a simple dropcasting method.

Facile preparation of highly electrically conductive films of silver nanoparticles finely dispersed in polyisobutylene-b-poly(oxyethylene)-b-polyisobutylene triblock copolymers and graphene oxide hybrid surfactants

RSC Advances ◽  
2015 ◽  
Vol 5 (124) ◽  
pp. 102462-102468 ◽  
Author(s):  
Chih-Wei Chiu ◽  
Gang-Bo Ou
Keyword(s):  
Electrical Conductivity ◽  
Silver Nanoparticles ◽  
Graphene Oxide ◽  
Triblock Copolymers ◽  
Film Surface ◽  
High Electrical Conductivity ◽  
Electrically Conductive ◽  
Conductive Films ◽  
Heat Treated ◽  
Facile Preparation

The melted morphologies revealed that the AgNPs possessed mobility, and melted on the film surface, giving a high electrical conductivity of 5.2 × 10−2 Ω sq−1 when heat-treated at 350 °C.

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