Iraqi journal of mechanical and material engineering

Manual metal-arc welding was carried out for ductile cast iron under welding conditions
of (90) A DC current (DCEN) and 20 volts. Welding wire type E- Ni -Fe- CI in diameter of
3.2mm was used and travel speed of 7 inch /min and welded through two passes. The weld
joined are examined using X-ray radiography, broken down joint are excepted. Corrosion
specimens prepared from free defects joints having measurements of (15*15*3) mm
agreeing to ASTM G71-31. Then Optical microscopy was employed to detect the welded
joint microstructure and base metal. Micro hardness was implemented using Vickers test.
Corrosion examinations are conducted using electrochemical potential state chamber in
equipped (sea water 3.5% NaCl),Corrosion examination is achieved using potentiostatic
polarization dimensions in saltwater 3.5%NaCl at potential scan rate (+100-100 mv/sec) to
estimate corrosion parameters by extrapolating. The corrosion rate was calculated by Tafel
equation. The results of corrosion rate can be predicted using a mathematical model using
data achieved from practical method and compare these results with the theoretical one,
results show that corrosion rate for welded joint is more than the base metal because of the
change in metal microstructure during welding process.

The present work deals with the isothermal analysis of worn journal bearing lubricated with
Nano-lubricants. The bearing wear affect the oil film thickness and causes a decrease in load
carrying capacity of the journal bearing. On the other hand, many works show that the
addition of Nano- particles to the oil enhances its viscosity. The main goal of the present
work is to investigate the ability of the Nano-lubricant to correct the wear effect on the
performance of such bearings. The modified Reynolds equation was solved using finite
difference technique to obtain the pressure distribution in the clearance gap of the worn
journal bearing. Dufran\'s model was used to include the effect of wear on the thickness of
the oil film. The effect of adding three different types of Nano-particles namely, Dimond,
CuO and TiO2 to the base oil has been investigated. Bearing static characteristics in terms of
load capacity, friction force, end leakage and power loss for different eccentricity ratios
have been investigated. The mathematical model has been validated for the pressure results
obtained in the present work with that obtained by other workers and the results found to be
in a good agreement. The results obtained in the present work show that the load carrying
capacity enhances by about40%, 9% and 3% for the bearing with wear depth parameter of
0.4, eccentricity ratio of 0.7 lubricated with oil containing TiO2, CuO and Dimond Nanoparticles respectively in comparison with pure oil lubricated bearing

Post flow model was used in the present study as an insert model for the interactive
flow study innovative device namely called ePIV. The separation of the flow and its
subsequent reattachment to a solid surface occurs in many systems, and is of practical as
well as of theoretical interest. Three different values for the upstream velocity were selected
in the present work within the range (14, 24, and 32 mm\\s) and two set of figures were
observed for every value of upstream velocity. First set for velocity vector plots and shaded
color plot while the second is for picture frames captured for the purpose of ePIV system
software. It was found that ePIV system can be used in diverse educational settings because
of its effectiveness as an educational tool, high-tech appeal, compact size, low cost and
safety. Also, It was concluded that the sudden appearance for the post height result in a
vortex spot that lead to an adverse pressure gradient concentrate the majority of high bulk
velocity magnitude at the upper half of the post flow model height

This study presents an experimental investigation of metastable region take place for
refrigerant flow through adiabatic and non-adiabatic capillary tube of window type air
conditioner. Large numbers of experiments are carried out to explain the effect of length of
straight and helical capillary tube on metastable region under adiabatic and non-adiabatic
conditions. for the case of adiabatic capillary tube, three different length are selected
(70,100 and 150) cm and two helical capillary tube, the length of each tube is 100 cm with
two coil diameters (2 and 6) cm. For the non-adiabatic capillary tube, the straight capillary
tube suction line is 150 cm while the length of non-adiabatic helical capillary tube is 200 cm
with 8 cm coil diameter. The results show that the length is the most influence parameters
on beginning of metastable region. In addition the helical coil tube effect on the beginning
of metastable region. As well as for the adiabatic and non-adiabatic capillary tube it is
concluded that mass flow rate is the main parameters on beginning of metastable region.
Also effect of length and coiling on both pressure drop and mass flow rate are discussed.
The CFD commercial code, ANSYS CFX 16.1 based on finite volume method using Kturbulence model considering the homogeneous flow between phases applied to straight
capillary tube. The present numerical data has been validated with the present work
experimental data and with other researchers. A good agreement is obtained which can be
lead to use ANSYS CFX 16.1 in the design and optimization of capillary tube in airconditioner.

In this work, a combination between latent heat storage materials (LHSm) and sensible
heat storage materials (SHSm) as new storage heat material in flat plate solar air heater was
tested experimentally. PCM (paraffin wax) at a certain ratios (10%) and (20%) were used as
LHSm with a pure cement (base material) as SHSm. The experimental tests was done
indoor at irradiance of (1000W/m2
) with forced convection, the mass flow rate of air are
(0.5kg/min) and (1.13kg/min). The results indicated that the enhancing thermo-physical
properties of adding pure cement by a certain ratios of paraffin wax led to enhancement in
thermal energy stored. The percentage increasing in storage heat duration time was (29%)
for compound cement with (10%PCM), (38.4%) for compound cement with (20%PCM),
compared with pure cement at (0.5kg/min) air mass flow rate. And at (1.13kg/min) air mass
flow rate, it was (33.3%) for compound cement with (10%PCM) and (52.6%) for compound
cement with (20%PCM) compared with pure cement.

In this research, cement mortar specimens were prepared with sand to cement
(1:2.75) and (1, 2, and 3 wt%) of ceramic oxides (MgO, ZnO and Al2O3) at different particle
sizes (11.8, 38.8, 109.8 nm), respectively. At curing time (7days), the (structural, thermal
and physical) characteristics of the mortar specimens were investigated.
The dry density and porosity results show that the values of density increased by
(23.4, 15.6, and 9.5%), and the values of porosity decreased by (76.2, 63.8, and 56.2%) for
(MgO, ZnO, and Al2O3), respectively with respect to the reference mortar specimen. The
thermal conductivity results show that the values of thermal conductivity decreased by
(47.27, 40.66, and 51.16%) for (MgO, ZnO and Al2O3) respectively, with respect to the
reference mortar specimen . Results of characterizations tests (XRD and optical microscope)
showed that the reference mortar specimen has high roughness with large number of
Ca(OH)2 crystals, as well as the presence of pores, while after adding the nanopowders, it
showed a decrease or disappearance of Ca(OH)2 and produced homogeneous structure of
calcium silicate hydrate compound (C-S-H), in addition to a large decrease in the pores and
surface roughness. This explains the significant improvement in the properties of cement
mortar mixed with nanopowders, hence these mortars were very appropriate for covering
walls, buildings and other outdoor building applications.

The heat transfer coefficient and temperature distribution of two phase flow (water, air)
in rectangular ribbed vertical channel was investigated experimentally and numerically in
this work for different values of water and air superficial velocities (0.0421, 0.0842, 0.1158,
0.1474 and 0.1684 m/s) and (1.0964, 1.425, 1.644, 1.864 and 2.193 m/s), respectively, at
constant heat flux (120 W). The distribution of temperature along the channel was
photographed using thermal camera and compared with images for the corresponding
contours which found numerically. The experimental results of heat transfer coefficient
compared with computational fluid dynamics model simulated by Ansys fluent 15.0. A
good agreement has been found between the experimental and numerical data, where the
percentage deviation between the experimental and the numerical results is (1% - 6% ). The
results showed that, the local heat transfer coefficient increased by adding ribs, it also
increased as the velocity of the flow increased.

In turning operation, numerous parameters are utilized to analyze machinability. Parameters,
for instant, tool wear, tool life, cutting temperature, machining force components, power
consumption, surface roughness, and chip thickness ratio are frequently utilized. The goal of
this work is to model the effect of cutting parameters (cutting speed, depth of cut and feed
rate) on the machining force and chip thickness ratio during turning ductile aluminum 1350-
O. Four fuzzy logic models were built to model the relationship between cutting parameters
and the three force components of machining force and the chip thickness ration. The inputs
to all fuzzy logic models are cutting speed, depth of cut and feed rate. Whereas, the output
for first, second, third and fourth models are cutting force, passive force, feed force and chip
thickness ratio, respectively. All fuzzy models showed good match to the experimental data
and the computed correlation coefficients were larger than or equal 0.9998. Those models
were used to optimize the cutting process and give the optimum cutting parameters

One of ways to improve properties of materials without changing the product shape to
obtain the desired engineering applications is heating and cooling under effect of controlled
sequence of heat treatment. The main aim of this study was to investigate the effect of
heating and cooling on the surface roughness, microstructure and some selected properties
such as the hardness and impact strength of Medium Carbon Steel which treated at different
types of heat treatment processes. Heat treatment achieved in this work was respectively,
heating, quenching and tempering. The specimens were heated to 850°C and left for 45
minutes inside the furnace as a holding time at that temperature, then quenching process was
performed in four types of quenching media (still air, cold water (2°C), oil and polymer
solution), respectively. Thereafter, the samples were tempered at 200°C, 400°C, and 600°C
with one hour as a soaking time for each temperature, then were all cooled by still air. When
the heat treatment process was completed, the surface roughness, hardness, impact strength
and microstructure tests were performed. The results showed a change and clear
improvement of surface roughness, mechanical properties and microstructure after
quenching was achieved, as well as the change that took place due to the increasing
toughness and ductility by reducing of brittleness of samples

Through the last two to three dictate, composite materials had being applied enormously in
many industry fields. This is as fact that this type of materials possess; high strength to
weight ratio, high stiffness, and limit thermal conductivity. In this work Nano-Yttrium oxide
with (0%, 1%, 2%, 3% and 4%) weight fraction had been added, as reinforcement phase, to
acrylic resin (cold curing). Various physical and mechanical tests had done for determining
the development in the properties of the prepared composite samples like: hardness, tensile
strength, thermal conductivity, water absorption and density. The results show: decreasing
tensile strength with increasing Nano-Y2O3 weight fraction, maximum decline in tensile
strength was at (4) % Y2O3, about (16.2) % of Acrylic strength; increasing in hardness with
increasing Nano-Y2O3 weight fraction, maximum hardness was at (4) % Y2O3, about (107)
% of Acrylic hardness, no obviously density change with increasing Nano-Y2O3 weight
fraction, decreasing water adsorption with increasing Nano-Y2O3 weight fraction, maximum
decreasing in water absorption percentage was at (4) % of Y2O3, about (93) % of Acrylic
water absorption, decreasing thermal conductivity with increasing weight fractions of NanoY2O3, maximum decline in thermal conductivity was at (4)% of Y2O3 , about (90)% of
Acrylic thermal conductivity

In this paper, the effect of surface modification of short glass fiber on some properties of
high-density polyethylene composite was investigated. The chemical treatment of short glass
fiber (SGF) with solvent ethanol was achieved, and composites with weight fraction (0.5, 2.5,
4wt. %) were fabricated. Mechanical behavior tests include (tensile strength, impact, and
hardness tests) and structure test (FTIR) were used. Values of mechanical tests for treated
short glass fiber – reinforced High density polyethylene composites were much better than
the neat high density polyethylene. The tensile strength value of composite from (37 to 41
MPa), impact strength from (83 J/m² to 100 J/m²), and hardness from (64 to 86 N/m²). Result
of FTIR test showed physical reaction without the formation of new peaks.

Compression buckling experimental tests was carried out for long and intermediate
columns made of 6061-T4 AL- alloy. Two different soil corrosion time were adopted i.e.30
days and 60 days using 27 samples. The experimental analysis revealed that increasing the
corrosion time negatively affects the mechanical properties of metals such as the specimens
of 60 days corroded have 1.68% reduction in ultimate strength, also increasing the corrosion
time reduces the critical load such as the maximum reduction was 4.24% in critical buckling
load for 60 days corrosion time. Perry-Robertson theory was applied to the experimental
data and it was found that the above theory can satisfactory predicted the critical buckling
load (Pcr) with a factor of safety equal to 1.2. The ratio of corroded Pcr to dry Pcr was
always less than unity. This indication explains the effect of pitting corrosion on buckling
behavior of 6061-T4 AL- alloy.

The reinforcement of Aluminum alloys opens a wide range of industrial application for
these alloys in areas where reduction of weight has first priority, in General this operation
known as metal matrix composite (MMC). In this study the nanocomposite material were
fabricated using stirring time for 6 minutes at 450 rpm stirring speed .Al-7075 alloy was the
base metal and the reinforcement nanocomposite material was the Alumina Al2O3 of 10
nanometer in grain size , which is used as weight percentage (wt%) for 0.3,0.5,0.7 wt%
Al2O3. The results show that the best enhancement in fatigue life and strength were occurred
at 0.3 wt% of Al2O3.

The high temperature corrosion behavior of thermal barrier coating (TBC) system
consisting of IN-738 LC superalloy substrate, air plasma sprayed Ni24.5Cr6Al0.4Y (wt%)
bond coat and air plasma sprayed ZrO2-20 wt% ceria-3.6 wt% yttria (CYSZ) ceramic coat
were characterized. The upper surfaces of CYSZ covered with 30 mg/cm2
, mixed 45 wt%
Na2SO4-55 wt% V2O5 salt were exposed at different temperatures from 800 to 1000 oC and
interaction times from 1 up to 8 h. The upper surface plan view of the coatings were
identified for topography, roughness, chemical composition, phases and reaction products
using scanning electron microscopy, energy dispersive spectroscopy, talysurf, and X-ray
diffraction. XRD analyses of the plasma sprayed coatings after hot corrosion confirmed the
phase transformation of nontransformable tetragonal (t') into monoclinic phase, presence of
YVO4 and CeVO4 products. Analysis of the hot corrosion CYSZ coating confirmed the
formation of high volume fraction of YVO4, with low volume fractions of CeOV4 and CeO2.
The formation of these compounds were combined with formation of monoclinic phase (m)
from transformation of nontransformable tetragonal phase (t').