'Thin films & coatings' Roadmap - Nano Mahidol

Although this production process has reached mass-production levels, for most
applications it implies high purity for solvents and starting materials. In addition to
these limitations, this process wastes a large amount material (very expensive in the
case of materials used in display production). Because of that, some experts
consider that this process will mostly be used as a research tool.
2.3.1.7 Spray coating
There are two main methods: plasma spray coating and thermal spray coating. The
plasma spray coating (also known as plasma arc plating, plasma arc spraying,
plasma coating), powders are introduced in a cavity that contains the gas stream of a
plasma gun. After being melted, the powders are projected onto the surface being
coated. With regard to the Thermal spraying coating, it consists of heating a feed
stock material (powder or wire) and accelerating it to a high velocity by a gas stream.
Then the particles strike the substrate surface and the particles deform and freeze
onto the substrate. The collision speed is an essential element, which directly
influences the coating properties.
Main barriers to success and research paths
According to the experts, process reliability is the main bottleneck. The control of 3
variables (material, heat and speed) is essential to get a reliable and reproducible
coating matching the expected requirements
2.3.1.8 Self-assembly
Self-assembling consist of designing atoms and molecules such that chemical and
physical processes will, under the right conditions, cause the atoms and molecules to
self-organise in the desired place with the desired structure. Self-assembly of thin
films (usually monolayers) generally occurs on a substrate that facilitates molecular
alignment and growth.
Main barriers to success and research paths
As one of the few bottom-up techniques, according to the experts, it’s still in its
infancy and for many types of coating a lot of basic science has to be developed prior
to its transfer to industrial environments. There are also a huge variety of possible
materials that could be incorporated in self-assembled structures and much of this
space has yet to be explored. The idea of having multiple interacting layers adds
another dimension to explore.
Problems that seem to be common to many other production techniques
(fundamental understanding or lack of suitable equipment) have also a higher impact
on the development of this technique.
One of the technical barriers specifically highlighted by the experts is related to
reactivity of molecules that can polymerize quite easily due to humidity rate in the lab
and form aggregates onto the substrates (thus reducing thin films’ performance).
The fact that self-assembled layers have a substrate-specific chemical formulation
and substrate pattern, according to the experts makes their development application
specific and, therefore, expensive.
15 Roadmap report on
Thin films and coatings