DEVELOPMENT OF NANOPARTICLES WITH TUNABLE UV ABSORPTION CHARACTERISTICS

1
 Protective Space coatings for Ti, Al and Mg
alloys Nanoscale materials based on organically
modified ceramics
A. R. Phani and S. Santucci   CNR-INFM
CASTI Regional Laboratory at Department of
Physics - University of LAquila, via Vetoio,
67010 Coppito, LAquila, ITALY
Tel [phone] Fax
0039-0862-433033 e-mail
sandro.santucci_at_aquila.infn.it or
phani_ayala_at_yahoo.com
Motivation
Objectives

Mg and its Space
Applications

Innovative approach

• The main objective of this proposal is to
  protect space materials from corrosion such as Ti
  and Mg alloys with nanostructured-
• multifunctional coatings.
• In the proposed system, deposition of
  nanolayering of inorganic and organic
  nanocomposite materials embedded with
  nanoparticles
• (corrosion inhibitors) with additional
  functional groups on the surface will be
  developed.
• These nanocomposite materials will be prepared
  by simple, wet chemical processing system
  (sol-gel process) at relatively low
• temperatures (gt 150 C).
• The basic structure consists of inorganic
  network with organic cross-linking or network
  modifying structural units. A main advantage
• of this system is the combination of
  hardness (coming from the high amount of
  inorganic network structures) and flexibility
  (coming
• from the nature and amount of cross linking
  structures).
• This could be possible by covalently bonding the
  networks leading to stable functionalisation and
  incorporating the corrosion inhibitor
• nanoparticles with in these networks to have
  corrosion resistance properties.

• Aerospace Value of a pound
  in
• segnment
  weight saved (Euro)
• Commercial --------------------
  357
• Space -----------------------------
  35.4
• Automobile ---------------------
  1.78 3.2

• Radical Innovative Approach
• This type of system will be applied on
  different types of Titanium, Magnesium and
  Aluminium alloys applicable to aerospace
  applications.
• It has been recognised by the aerospace
  industries that the degradation of carbon-based
  materials (organic coatings) in low earth orbit
• (LEO) is due to the presence of ground state
  atomic oxygen, ultra-violet radiation and
  vehicles extreme velocity.
• The UV radiation that is present in low earth
  orbit is of adequate energy to cleave organic
  bonds, which can bring about chain scission and
• cross-linking reactions in organic
  polymeric materials. In addition to this, thermal
  cycling, particulate radiation, vacuum, and
• micrometeoroids and debris affect organic
  materials.
• In this respect, materials consisting of
  inorganic/organic (polymer) can offer protection
  from atomic oxygen as well as UV radiation and
  high-
• energy particles via the in situ
  fabrication of nanophase silicon / metal-oxo
  clusters.
• Siloxane polymers, which have rates of erosion
  one to two orders of magnitude slower than
  organic polymers in low earth orbit, have been
• chosen in the present investigation.
• In addition, to slower erosion rates, when
  exposed to atomic oxygen siloxane polymers form
  protective silicon oxide barrier.

Fig 1 Schematic diagram of the nanoscale hybrid
structure for multifunctional properties
for light-weight alloys applied for space
applications
Background

• Magnesium alloy has a light weight, high thermal
  conductivity, high dimensional stability,
  good electromagnetic shielding,
• high damping characteristics, good
  machineability and as well as recyclability
• These properties make it valuable in a number of
  applications including automobile, aerospace
  components, mobile phones,
• sporting goods, handheld tools, and
  household equipment
• The use of magnesium alloys can significantly
  decrease the weight of automobiles without
  sacrificing structural strength
• Unfortunately, magnesium alloys have a number of
  undesirable properties including poor corrosion
  and wear resistance, poor
• creep resistance, and high chemical
  reactivity that have hindered its widespread use
  in many applications

• The proposed mechanism explains where a space
  debris erode a part of coating which
• is self healed by consuming the atomic
  oxygen present in the space, there by forming a
• new protective layer which can withstand
  both atomic oxygen degradation, high energy
• UV radiation and atomic particles.
• Once the coating is exposed to atomic oxygen a
  protective layer of silicon oxide
• is formed and with the incorporation of
  silicon-metal-oxy-clusters the coating should
• protect against atomic oxygen erosion, high
  energy particles, and deep UV radiation.

Sol-gel Process

Sol-gel Nanotechnology
Applications

Project Goals
Scientific and Technological Objectives that
CASTI might pursue in this project To optimize
the developed pretreatment process for light
weight alloys prior to the deposition of the
nanostructured coatings for better adhesion
strength To deposit organic-inorganic hybrid
nanocomposites embedded with functional corrosion
inhibitor nanoparticles (CeO2, La2O3) To
deposit low friction, wear, scratch, abrasion
resistant inorganic-polymer hybrid nanostructured
coatings as top layer with additional
hydro-oleophobic properties to fulfill the
objective of the multifunctional coatings. To
characterize the deposit or thermally treated
coatings for their structural, mechanical,
tribological and corrosion (salt spray) and
humidity resistance (intermittent, prohesion, and
condensation humidity tests) measurements. To
optimize the developed nanocomposites embedded
with nanoparticles for scale up process upon
dealing with the industrial partners in the
respective countries in the field of automobile,
aeronautic, construction and microelectronic
industries. Services offered by CASTI in the
project CASTI will analyze the coated samples
as well as corrosion resistance tested (salt
spray test) samples by employing full length
scale characterization techniques available in
the laboratory.