Al-Qadisiyah Journal for Engineering Sciences

The investigation on the thermogravimetric analysis of unsaturated polyester
matrix composites reinforced with untreated saccharum fibers and other treated by
alkaline solution of NaOH with four weight percent include 0.5, 1, 2 and 2.5% was involved
in this work. Generally the incorporation of saccharum fibers slightly change the thermal
stability of the unsaturated polyester matrix by the weight loss value and only for
reinforcement by unsaturated sacchrum fibers and that treated in 2.5% NaOH.

The present research, studies the effect of adding two different types of
reinforcing powders, which included: Bamboo (Ba) and Rice Husk (RH), that added with
different weight fractions (2, 4, 6 and 8 wt. %), and with the selected size particles of
(25µm and 75µm) on thermal behavior of heat Cure Poly (Methyl Methacrylate) such as
thermal conductivity and thermal diffusivity in addition to the differential scanning
calorimetry (DSC) analysis and these tests were accomplished at temperature of
laboratory. The poly Methyl Methacrylate properties which reinforced by (Bamboo and
Rice Husk) powders are mainly influenced by the interfacial adhesion strength between
the powders and the matrix, and in order to get better correlation between the natural
powder and PMMA matrix, so the powders were treated with alkali (sodium hydroxide
NaoH) solution prior to use as reinforcement materials. The results showed that the values
of the thermal conductivity and thermal diffusivity increased with increasing of the weight
fraction for both particle sizes (25 µm and 75 µm) of natural powders.

: In this paper the effect of surface roughness on the performance of counter flow
microchannel heat exchanger has been numerically investigated. The studied
Microchannel heat exchanger is a square shape and made of aluminum as substrate
material with different values of hydraulic diameters (20, 50, 110, 150 ) μm. The working
fluid used is water at constant properties. Roughness- viscosity model has been used to
study the roughness effect with 0.14 ratio of roughness to hydraulic diameter. The results
obtained indicate that pressure drop of (CFMCHX) increased with increasing surface
roughness and decrease hydraulic diameter also the results showed that there is a slight
increasing in thermal performance with increasing the surface roughness.

: In this research stir casting technique is used to produce (ZA-27)alloy
hybrid composites reinforced by nano particles (BN and Si3N4) with various weight
percentage.The wear test were used pin on disk for both (ZA-27) alloy
and all composites.The results indicate that the value of hardness increased
with increasing the additives of nano (BN and Si3N4) percentage for ZA-27
hybrid metal matrix composites. It was found that the nano particles play
an important role in improving the wear properties of alloys. Since nano particles
impede dislocations movement, causing enhancement in the mechanical properties.