In this research we studied the relationship between the optical conductivity Ϭop and
photon energy (hν), the absorbance coefficient (α), transmittance (T), the refractive index
(no), and the real part and imaginary part of dielectric constant (εr,
εi), the spinning velocity
of deposition device (v), for a specific wave length (600nm), for a pure thin film prepared
from an organic polymer material, Polystyrene (PS), by spin coating technique, on three
velocities ( 1000-2000-3000)RPM, in room temperature and 1atm.
It was shown that the PS film is a transmittive film with a transmittance values
reach ( 85 – 90 )% in the infrared region, and the optical conductivity Ϭop increased with
the photon energy, and for the velocity 1000RPM it took the highest value ( 1.67 X
1014 )1/sec, at the photon energy (hν =3.1 ev) and the wave length ( λ= 400nm ),
which means that the optical conductivity Ϭop is active in the visible region, and also it
decreases with the spinning velocity.
The values of energy gap for allowed direct transitions were (2.5ev), (2.4ev), (2.3ev)
for the films prepared on 1000RPM, 2000RPM, 3000RPM, and for the forbidden direct
transitions were (2.3ev), (2.2ev), (2.1ev) respectively .
The biggest value of Urbach energy Eu was (163mev) on the velocity 1000RPM and
the lowest value was (109mev) on the velocity 3000RPM.
In This research a surface hardening process by Ni coating and
subsequent diffusion heat treatments was studied at Al7075 alloy.
Nickel coatings with different thickness were obtained.
In this research we have prepared thin films from poly vinyl chloride (PVC) by spin
coating technique in three velocities (1000,2000,3000)RPM on glass substrate (Micro
scope cover glass), at room temperature. The absorbance A, and transmittance T f
or the
films were studied in the visible and ultra-violet region (UV-VIS). In addition,we have
calculated the absorbance coefficient α, skin depth δ, refractive index no, dielectric
constant ε (the real part and the imaginary part), also we have calculated the energy band
gap of allowed and forbidden direct transitions.
The films showed high transmittance (80-90)%, in the infrared region as a function
of the spinning velocity and took the maximum value 80% for the velocity 1000RPM, and
90% for the velocity 3000RPM, and the refractive index was decreased with the velocity
increase, we found it between3.67 and 4.56 for the velocities 3000RPM and 1000RPM
respectively. Whereas the skin depth δ decreased with the increasing of velocity, the
minimum value was 0.0000531cm for the velocity 3000RPM and the maximum value was
almost 0.00023cm for the velocity 1000RPM.
In this research, has been studied the spread of chromium atoms mechanism, and mechanical and chemical and properties of the diffusion chrome coating layer in low carbon steel, which is considered one of the surface treatment techniques. Where many p
ractical experiences were carried out in the powdery saturation milieu to form a diffusion coating layer containing atomic chromium who will spread inside the painted
surface, and has studied some mechanical and chemical properties after doing diffusion chrome coating.
The tests results showed that the tensile strength and micro hardness and chemical corrosion resistance improved after the diffusion chrome coating, also increased the depth of coating layer By increasing the retention time in the oven and temperature, where this relationship is reflected with curve of the second degree. Conversely ductility decreased.
Search results confirm the possibility of using diffusion chrome coating as a promising treatment in raising the efficiency of machinery elements that prone to oxidation or chemical corrosion in different temperatures.
This study deals with the friction and wear behavior of coating layers (fluoride and Graphite).The coatings are thermally sprayed on cast iron disks. Sliding is performed between cylindrical pins manufactured from organic brake linings and the coated
and uncoated disks. The coatings are characterized by measuring their hardness, porosity, and corrosion resistance. The corrosion resistance of the coating is tested by exposure to Nacl for 150 hours; the coating layer has had the best corrosion resistance. The friction and wear tests are conducted under contact pressures of (1.5 MPa to 7 MPa) and sliding speeds of 1 and 3 m/sec.
In this research project, the EPON 828 /Hardener 2512 epoxy resin coating
has been prepared at the ambient laboratory temperature with different epoxy/
hardener ratio.
There has been much interest in photonic and spectroscopic devices that are
useful for controlling transmission and reflection coefficients such as multilayer
thin films, photonic crystals, and various Bragg structures in the form of
molds or multilayer thin films.
Photonic crystals is a low-loss periodic medium with periodic changes of
refractive index, which is used to control the light.
Theoretically, Photonic crystals can be studied using Maxwell equations, but
it’s difficult to find a general analytical
solution for these equations, since we
are dealing with vectors. So we resort to the numerical solutions for Maxwell’s
equations to calculate the reflection and transmission coefficients and the
Photonic band gap.
Mixtures of ammonium acetate and ammonium tartrate in the presence of
benzyl alkyl dimethyl ammonium chloride (benzalkonium chloride) were used
for sealing sulphuric acid anodized aluminium.
Mixtures of ammonium acetate and ammonium tartrate exhib
ited
synergistic sealing effect, which offered excellent durable corrosion protection
to the surface coating formed by anodizing the aluminium alloy. Moreover the
synergistic effect of benzalkonium chloride with tartrate offered boehmite free
sealed surface coating.
Quality and durability of the sealed aluminium oxide films have been
assessed using standard control sealing quality tests and well-known
salt- spray (fog) test (ASTM B 117-97).
There are wide uses of tin oxide thin films, especially in the field of
transparent conductors, solar cells, gas sensors and piezoelectric materials.
Laser deposition is considered one of the most important techniques followed to
obtain these film
s. In this research, we develop a technique to obtain
homogeneous thin films of tin oxide depending on vaporization of pile targets of
this oxide by continuous CO2 laser in the atmosphere, with a fan which
guarantees obtaining homogenous films. Some of these films were annealed in
different conditions. The optical microscope images revealed the presence of
high degree of homogeneity, while the X-Ray study showed different
crystallization grain orientations which depend on the preparation conditions.
The preferred direction is (110). The optical absorption gives information
about the value of the effective band gal for the samples before and after
thermal annealing. We have found that some films have Eg = 3.2 ev. before
annealing, and after long annealing they have Eg=1.3ev. In addition, the hard
annealed thin films reveal anisotropy in the optical and electrical.
Characteristics, they have different absorption coefficients in two
perpendicular directions, also there is an electrical resistance anisotropy along
these two directions especially after hard annealing. The Eb was 0.73 ev before
annealing, it became 0.37 ev for one direction and 0.32 ev for the other
direction.
