Nanotechnology Alumina Nano particles

ALUMINA NANO PARTICLES
A presentation by:
SAMAR NOURELDIN
OMER MOHAMMED
MARAM FARAH

Alumina can called :
aloxide
aloxite,
 alundum
depending on particular forms or
applications.

Alumina nanoparticles applications
 alumina are Thermal insulator, High Temperature
Stability will allow it to use in many industrial and
institutional work.
 in ceramic industry.
 In polishing/abrasive applications.
 as an absorbent.
 in the refractories
 as catalysts.
 wear resistant coating.
 medium for chemical chromatography

Sol-Jel method.
emulsion combustion method (ECM).
Spray Pyrolysis method(hot wall aerosol
synthesis method ).
Hydrothermal method.
Co-Precipitation method.
Mechanical milling.
Vapour phase reaction and Combustion
method.
Methods of preparation

Here we will explain only the three
most important methods

• nanoscale alpha-alumina (α-Al2O3) powder is
smaller than (Nano-Al2O3) but it’s difficult to obtain
due to :
α-Al2O3 is in a stable phase after calcining at high
temperature.
α-Al2O3 particles tend to aggregate during
dehydration process in wet chemistry method.
Sol-gel method can solve these problems

 uses relatively low temperature.
 can create very fine powder.
the possibility to obtain high purity materials.
Sol-gel method
advantages

• There are different precursors used in the
synthesis of alumina by sol-gel method were of
different chemical nature such as:
inorganic – aluminium chloride (AlCl3) .
organic– aluminium triisopropylate (C3H7O)3Al.
Aluminum isopropoxide Al (OC3H7)3

The produced particles
characterized by, X-ray diffraction

The produced particles
characterized by SEM micrographs

the particle become finer
and less agglomerated until
48 hour stirring. The particle
started to agglomerate and
to be more dense in
structure at 60 h.

figure” a”
The size of particle
after 24 hours of
stirring in range of
270–320 nm and
had a lot of
agglomeration.

Figure” b”
the size of particles,
after 36 hours of
stirring, fell in the
range of 250–
300 nm, and had a
lot of agglomeration.

Figure”c”
the size of particles,
after 48 hours of
stirring, fell in the
range of 20-30 nm,
and had a good
quality of dispersion.

Figure (d)
after 60 hours of
stirring, the sizes of
particles were in
the range of 150–
200 nm and a lot of
agglomeration and
only little dispersion
were observed

Its main application
In metal-matrix composites for
nanoreinforcements

Method description
• it’s based on ultrasonic generation of
micrometric-sized aerosol droplets and their
decomposition at intermediate temperatures
(400-800ºC).
• it possible to control important particle
properties (size, morphology, chemical
composition, etc.) simply by controlling the
process parameters (residence time,
decomposition temperature).

Particle synthesis
 An aqueous precursor solution prepared by dissolving the corresponding
amount of aluminium nitrate nonahydrate (Al(NO3)3·9H2O.
 The initial solution was atomized using an ultrasonic vibrating frequency of
2.1·106 s-1.
 The aerosol transported into a reaction zone and decomposed at 700°C.
 Air used as a carrier gas .
 the powders were isothermally annealed in air at 800 - 1300 oC for 12 hours
(chamber furnace CHESA) to promote phase crystallization.
 The particles water collected at exhaust “.
 The predicted particle size, Dp, can be expressed as a function of the
droplet size, Do.

 The amorphous and polycrystalline character of the particles.
 Initially the particle morphology does not change significantly with
annealing.
 As the temperature of thermal treating increase , the η-Al2O3 phase
continues and the particles tends to form the peaks (alfa-Al2O3
phase) and loss there spherical shape .
 there is a contamination of SiO2 from the quartz tube.
 particles obtained by aerosol decomposition are spherical, smooth,
non-aggregated and relatively uniform in size(≤ 400 nm).
 confirm high compositional uniformity and the exclusive presence of
the constitutive elements (Al and O).
Particle characterization

Experimental X-ray diffraction patterns

SEM
micrograph of
“as-prepared”
Al2O3
particles,

TEM
analysis(secondary
particles)

this method was originally developed in
1997 in Japan.
It is compination of :
emulsion process + combustion
technology
The ECM is classified into liquid phase
syntheses but it also has the features of
gas phase syntheses.

produce high performance ceramic
powders
Its main application

An isolated small reaction field.
Short reaction period ” less than half a second”.
gives synthesize fine and chemically
homogeneous metal oxide powders.
It’s a continuous fabrication procedure which
contributes to lower production costs.
(ECM)method
advantages

Particle formation
mechanism(synthesis)
it is simmillary like the Hollow particles have been
synthesized by spray pyrolysis where the aqueous
droplets containing metal ions are rapidly heated at
their surface.
but here the surface of emulsion droplets is rapidly
heated by the combustion of the surrounding
kerosene film.
 The fast heating rate results in the unusually thin
shell structure .

collection of the ceramic powder produced
combustion of the atomized emulsion
preparation of an emulsion “ An aqueous solution
W/O type
Preparation procedures

Particle characterization
 The particles are spherical in shape.
 their diameters in the range 200–800 nm.
 The particles exhibited the unique characteristics of
hollow structure with extremely thin (10 nm) shell.
 The specific surface area is 56m2/g.
 In XRD profile of the hollow alumina powder The broad
peaks are identified with gamma phase alumina.

TEM image of the
typical alumina
powder
synthesized by
the
ECM(1mikro.m)

Nanotechnology Alumina Nano particles

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