The steel is prone
to the corrosive effects of water, salt and organisms. Now, researchers
have demonstrated
a way to make steel stronger, safer and more durable. Their new surface
coating is the
most durable anti-fouling and anti-corrosive material to date, capable of
repelling any kind
of liquid even after sustaining intense structural abuse. (Photo/Wikicommons)
HARVARD RESEARCHERS DESIGN MOST DURABLE ANTI-FOULING
MATERIAL TO DATE
(October 20, 2015) Steel
is ubiquitous in our daily lives. We cook in stainless steel skillets, ride
steel subway cars over steel rails to our offices in steel-framed building.
Steel screws hold together broken bones, steel braces straighten crooked teeth,
steel scalpels remove tumors. Most of the goods we consume are delivered by
ships and trucks mostly built of steel.
While various grades of steel have been developed over the
past 50 years, steel surfaces have remained largely unchanged — and unimproved.
The steel of today is as prone as ever to the corrosive effects of water and
salt and abrasive materials such as sand. Steel surgical tools can still carry
microorganisms that cause deadly infections.
Now, researchers at the Harvard John A. Paulson School of
Engineering and Applied Sciences (SEAS) have demonstrated a way to make steel
stronger, safer and more durable. Their new surface coating, made from rough
nanoporous tungsten oxide, is the most durable anti-fouling and anti-corrosive
material to date, capable of repelling any kind of liquid even after sustaining
intense structural abuse.
Accelerated
corrosion test, in which unmodified stainless steel (300 grade) (right sample)
and the lower part
of the TO-SLIPS sample with a 600-nm-thick porous TO film on steel
(left sample)were
exposed to very corrosive Glyceregia stainless steel etchant.
(a-h) Images show
corrosion evolution as a function of contact time.
The new material joins the portfolio of other non-stick,
anti-fouling materials developed in the lab of Joanna Aizenberg, the Amy Smith
Berylson Professor of Materials Science and core faculty member of the Wyss
Institute for Biologically Inspired Engineering at Harvard University.
Aizenberg’s team developed Slippery Liquid-Infused Porous Surfaces in 2011 and
since then has demonstrated a broad range of applications for the super-slick
coating, known as SLIPS. The new SLIPS-enhanced steel is described in Nature
Communications.
“Our slippery steel is orders of magnitude more durable than
any anti-fouling material that has been developed before,” said Aizenberg. “So far, these two concepts – mechanical
durability and anti-fouling – were at odds with each other. We need surfaces to
be textured and porous to impart fouling resistance but rough nanostructured
coatings are intrinsically weaker than their bulk analogs. This research shows
that careful surface engineering allows the design of a material capable of
performing multiple, even conflicting, functions, without performance
degradation.”