SPECIFIC MATERIALS-INTERFACE
BARRIERS
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Materials interfacial barrier challenges are a primary, if not defining, bottleneck in just about every major area of cutting-edge technology, whether in advanced memory devices, advanced photonics, medical devices, hypersonics, high-efficiency fuel cells, high-efficiency electrolyzers, battery technology, GenIV Nuclear reactors, molten salt reactors, high-concentration solar power, supercritical CO2 turbines, and…the list goes on.
Since and the related phase/morphology development of such interfacial barrier challenges is almost implicit to the development of such next-generation devices, Helicon efforts (this includes our divisions, Helicon Research, Helicon Thin Film Systems under Helicon Corp) have been continuously involved in, specifically, high-temperature barrier multilayers since its principal worked in crystal growth and interfaces of thin-film lithium niobate in 1990-1993, after already having considerable experience in plasma activated, reactive vapor deposition.
HIGH-TEMPERATURE BARRIERS:
HIGH-TEMPERATURE BARRIERS:
PLEASE SEE HELICON CORP WORK IN RELATED AREAS VIA LINKS:
- Molten Salts
- Nuclear Detection
- High-temperature Solid-Oxide Electrolysis
IN THIS BARRIER CATEGORY we are typically discussing what are barrier technologies that prevent degradation of performance due to the solid-state diffusion processes, which become increasingly dominant in the sort of devices that withstand the refractory environment of a high temperature furnace. Helicon has decades of experience in each of designing, fabricating, and testing surface coatings for numerous extreme environments.
We develop and implement multi-layer and graded high-temperature thin film barrier designs typically so as to allow a technically-critical component to withstand high-temperature and corrosive environments that would, normally, only be associated with certain refractory ceramics, thus obtaining a unique combination of useful properties that must be tailored for the specific application..
Barrier films for high temperature applications are implemented as means for preventing diffusion processes that eventually lead to shorten device lifetime, unstable operation, or both. Helicon has a long history in high-temperature (500C to >1200C) thin film barrier technologies, utilized successfully in applications ranging from high-temperature-gradient interfaces, locally or rapidly heated crystal-growth interfaces, corrosion barriers in high-temperature catalyzers, electrolyzers, and high-temperature fuel cells. We have experienced know-how and capabilities in the thin film process, and development metrics, for of an array of complimentary refractory dielectrics, conductors, mixed conductors, semiconductors, and other high-temperature compounds that are utilized in non-equilibrium conditions, steep temperature gradients, high-cycling applications, and corrosive environments.
Our barrier and solid oxide technologies have been successfully implemented for use in a number of NASA martian and lunar mission applications, solar cell production reactors, as well as in providing successful benchmarks in the world's largest high-temperature fuel cell companies. Our capabilities and experience in this area utilize multiple refractory materials that involve learning curves, including dense compounds of Borides, Carbides, vacuum diffusion bonding and post-deposition process regimes.
CORROSION BARRIERS:
CORROSION BARRIERS:
"Corrosion barriers" herein represent materials barrier applications in unpredictably complex environments, wherein the chemical potential driving diffusion will historically be a dominant failure mechanism in devices/applications, even without the added challenges of repeatedly cycling the prospective device/structure into incandescent/refractory temperature regions, such as was addressed in the above “high-temperature” barrier category.
Whereas the example provided here is work performed in enhanced, protected silver that provides theoretical maximum spectral reflectivity while withstanding the aggressive outdoor environments of heliostats, parabolic reflectors, as well as the higher-irradiance of secondary optics in certain high-concentration solar concentrators (e.g, Cassegrain-type).
Thin-film organic-inorganic multilayers barriers by a proprietary hybrid modified "hot-wire" monomer curing method utilized in one of our multi-source vapor deposition systems at Helicon facilities.
RELIABILITY TESTING REGIMES
Corrosion can still be a defining issue in the relatively gentle environments of indoor/lab/medical devices (as addressed below, under “environmental barriers”) wherein the "environment" is more narrowly defined; however, many of the most challenging applications are found in the present category of technologies/applications wherein performance and corrosion processes are highly-coupled (as opposed to performance degradation through impurity contamination, grain-boundary migration, electronic quenching, mechanical stress-failure, etc., etc.) as is typically the case in the high-exposure, out-door applications presented in this section, wherein the environment and its chemistry are highly variable.
In these applications, the ultimate cost-benefit profile is highly dependent on achieving a many-year cycling-lifetime under continual outdoor exposure conditions. As usual, the various outdoor exposures that bring on this corrosion are highly complex and multi-variant. A host of Reliability Testing regimes are typically utilized so as to quickly develop an understanding of expected long-term performance (e.g., 10 years, or, etc.).
ENVIRONMENTAL BARRIERS:
ENVIRONMENTAL BARRIERS:
Applications in the area of electronic/medical device barriers are typically quite similar in requirements to the typically more-aggressive environments of the earlier-discussed corrosion barriers, whereas precise function and zero-tolerance to point failure is frequently more rigidly required.
For example, organic electronics and flexible electronic devices are typically not exposed to multiple years of out-door, direct-sun exposure as in the case of many applications in the preceding “corrosion barriers”. However, a combination of zero-tolerance to failure-points, increased flexure, and extremely-low diffusion/permeation rates will produce a different set of challenges.
• Medical devices
• Biological detection devices
• Organic light-emitting diodes
• Flexible electronics devices
• Flexible photonics devices
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