Results in Surfaces and Interfaces,
Journal Year:
2024,
Volume and Issue:
16, P. 100243 - 100243
Published: June 22, 2024
Chemical
conversion
coating
(CCC)
is
a
cost-effective
and
industrially
scalable
technique
to
tackle
the
issue
of
corrosion
Magnesium
its
alloys,
crucial
for
reducing
global
greenhouse
gas
emissions
by
road
transportation
sector.
Amongst
all
possible
CCCs,
phosphate
(PCC)
has
one
highest
industrial
application
potential.
This
article
demonstrates
limitations
in
traditional
understanding
Mg-PCC
mechanism,
primarily
dictated
increased
local
pH
near
Mg-substrate
leading
double
deprotonation
phosphoric
acid
(H3PO4
→
H2PO4-
+
H+;
HPO42-
H+).
The
further
reacts
Mg2+
subsequent
supersaturation
precipitate,
MgHPO4.3H2O
results
formation.
new
hypothesis
proposed
based
on
argument
that
second
reaction
energetically
unfavorable,
instead,
mostly
limited
first
resulting
H2PO4-.
forms
an
intermediate
complex
ion,
(Mg2+-H2PO4-)+.
Mg
substrate,
when
exposed
aqueous
environment,
releases
Mg2+,
negatively
charged
substrate.
(Mg2+-H2PO4-)+
ions
are
electrostatically
attracted
substrate
responsible
MHPT
(MgHPO4.3H2O)
coating.
supported
thermodynamic
calculations
through
density
functional
theory
(DFT)
experiments.
Magnesium
alloys
are
often
used
in
bone
repair
surgeries
due
to
their
biodegradability
and
excellent
elastic
modulus,
making
them
a
promising
alternative
traditional
nondegradable
implants
like
titanium
alloys.
However,
rapid
degradation
rate
limits
use
as
the
body.
To
enhance
corrosion
resistance
bioactivity
of
magnesium
alloys,
we
applied
an
ultrasonic
spray
coating
on
microarc
oxidized
(MAO)
AZ31
alloy,
using
mixture
silk
fibroin
(SF)
nanohydroxyapatite
(nHAp).
This
SF/nHAp
composite
embeds
directly
into
micropores
MAO-treated
surface
without
additional
physical
or
chemical
treatment,
forming
stable
interlocked
structure.
The
effects
different
parameters
adhesion
interface
characteristics
were
investigated,
leading
development
corrosion-resistant
highly
biocompatible
coating.
Further
biological
evaluations
conducted
through
subcutaneous
implantation,
assessing
vivo
samples
surrounding
tissue
response
from
multiple
perspectives.
A
novel
concept
tissue-reactive
coatings
was
proposed,
suggesting
that
materials,
early
stages
postimplantation,
enable
fibrous
tissues
closely
adhere
surface,
thereby
slowing
material
degradation.
As
result,
bioactive
MAO-SF/nHAp
significantly
enhances
reduces
hydrogen
evolution,
promotes
regeneration
tissues,
minimizes
postimplant
inflammation.
approach
offers
new
strategy
improve
biocompatibility
vivo,
overall
evaluation
biodegradable
should
focus
more
in-body
corrosion.
