Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Alumina

Experimental and Numerical Analysis of Bulletproof Armor Made from Polymer Composite Materials

Jawad Kadhim Oleiwi; Abass Khammas Hussein; Sura Hameed Ahmed

Engineering and Technology Journal, 2015, Volume 33, Issue 7, Pages 1583-1597

This work focuses on the preparation of polymer matrix composite specimens by (Hand Lay-Up) method to make bulletproof armor from the unsaturated polyester resin (UP) as a matrix reinforced by Kevlar fibers at different volume fractions with and without (3%) of Al2O3 powder. The tensile test was performed for these composite specimens which include: (modulus of elasticity, tensile strength and elongation percentage), in addition of ballistic test were studied.
The results of this work show that the values of tensile test increase with increasing the volume fraction of fibers. And the values of tensile test of a composite reinforced by kevlar fibers and addition (3%) of Al2O3 powder was less than those composite without addition of Al2O3 powder.
The numerical method based on FEM was used to analysis of the bullet proof armor ballistic test of the composite specimens by finding the values of stresses, strains and deformations.
The numerical results that obtained from the program (ANSYS 14.5) represent the maximum value of stress happened to the composite specimens when reinforced by eight layers of the kevlar, and vice versa to the deformations and strain also the numerical results shown a good agreement with results that were obtained experimentally.
Results of ballistic test of composite specimens show the volume fraction of fibers has an effect on the deformations of the front face and back face of these composite specimens. And the values of the ballistic test for the composite reinforced by kevlar at eight layers give the best values from other each of composite specimens.

Experimental Stability and Thermal Characteristics Enhancement Analysis of Water Based Boehmite Nano fluid

Atia; Mohammed Hussein J. Al; Sarah A. Abed

Engineering and Technology Journal, 2015, Volume 33, Issue 7, Pages 1193-1210

In this work attempt was made to formulate water based boehmite (AlOOH) nanofluid in one and two steps methods. Boehmite is the first born alumina phase as prepared by sol gel route using aluminum isopropoxide precursor, exhibit a combination of excellent consistency and dispersibility in water. Plain nanofluids containing boehmite at different concentrations were investigated for colloidal, suspensions and/or dispersions stability and thermal conductivity enhancement. X-ray diffraction analysis, laser diffraction particle size analysis, viscosity, thermal conductivity measurements, TG/DSC thermal analysis and sedimentation balance were used as characterization tools. The results show promising long-term fluid stability and thermal conductivity enhancement relative to starting based fluid following non-linear dependence on particles concentration. The maximum 2.7 times enhancement in thermal conductivity occurred at narrow boehmite concentration range as a result of achieving optimum nanoparticles aggregation level where neither the case of nanoparticles homogenous dispersion nor the case of fully aggregated clusters could retain these enhancements values. This far beyond behavior from Maxwell's model was explained on the basis of the known mechanisms of thermal conductivity enhancement of nanofluids.

Study some thermal properties for hybrid composite reinforced with particales

Ali Hassan R.Al-Azzawi; Balkees M. D.AL-Dabbagh; Sana Ali .j

Engineering and Technology Journal, 2015, Volume 33, Issue 7, Pages 1330-1336

In this work a hybrid composite materials were prepared containing matrix of polymer blend (Novolac 80% + Epoxy 20%) reinforced by different reinforcing materials (Alumina Powder (type α) + Silica Powder + Asbestos short fiber) with two values of volume fraction (30, 40) %.

The hybrid composite materials prepared are:
• H1 = Blend + Al2O3(α ) + AS (30) %
• H2 = Blend + SiO2 + AS (30) %
• H3 = Blend + Al2O3 (α ) + SiO2+ AS (30) %
• H4 = Blend + Al2O3(α ) + AS (40) %
• H5 = Blend + SiO2 + AS (40) %
• H6 = Blend + Al2O3(α ) + SiO2+ AS (40) %
All samples related to mechanical, thermal, electrical and physical tests were prepar by hand lay up process. The tests can be classifi into four groups: For the (H1) samples, there was high tendency to loose weight with high temperature and less as to the samples (H6).

Influence of Power Density and Exposure Time on Laser Drilling Hole

Saad Kariem Shather; Mohammed Sattar Jabbar

Engineering and Technology Journal, 2014, Volume 32, Issue 9, Pages 2313-2321

laser drilling play an important role in special applications with high accuracy dimensions, this paper was focused on two types of ceramics; aluminum oxide (Al2O3) and zinc oxide (ZnO) of 4 mm thick have been drilled by using continuous wave (CW) CO2 laser. the exposure times applied were (20, 40, 50) sec and the other laser parameters were kept constant and to avoid large distortion, A comparison between the two kinds of ceramic are carried out to determine the effect of laser parameters on them. It founds that ZnO holes are cleaner than Al2O3 holes. Experiments proved that Exposure time at 50 sec resulting in similar penetration depth of 1.5 mm for both materials. Also for exposure time 41 sec gives the same taper angle.

Developing the Alumina Hybrid Sol-Gel Coating for Steel Oxidation Protection at High Temperatures

Atia; Mohammed Hussein J. Al

Engineering and Technology Journal, 2014, Volume 32, Issue 4, Pages 744-758

The use of nano alumina thin film by hybrid sol-gel route to protect steel from high-temperature oxidation is limited due to the low thermal stability of this coat. In this work, study has been conducted to minimize this effect. The chemical compositions of solid gel (xerogel) obtained from normal alumina hybrid sol-gel were thermally varied, and then recombining with water to form the modified coating solutions at constant concentration of 0.25mol/l alumina. Laser diffraction technique has been used to measure the growth of clusters sizes in different modified solutions. X-ray diffraction analysis to characterize the alumina phase's changes as a function of temperatures. Also gravimetric weight change method to determine the oxidation rate of steel before and after coating. The results showed five changes in alumina phase during heating to 9500C, which are similar to that recorded for the natural ore of boehmite, and the partial removal of non stable by-products constituents associated with xerogel has considerable effect on the degree of particles aggregation and agglomeration in solutions. This worked to improve the thermal stability of the coating layer, and show considerable resistance to cracks formation. At 40-50% removal, the oxidation rate of HSLA steel specimens was enhanced by 88 % at 9500C compared to the steel before coating.

Comprehensive Electrochemical Evaluation of Protective Coatings Properties by Sol-Gel Route for Stainless Steel Corrosion

Atia; Mohammed Hussein J. Al

Engineering and Technology Journal, 2013, Volume 31, Issue 4, Pages 71-86

Sol gel nano ceramic coatings have been applied on stainless steel to develop their biological characteristics and increase resistance to corrosion and wear. In this work nine electrochemical parameters were calculated, adopted to set a comprehensive evaluation map for protective properties of the coatings obtained based on occurrence degree of cracks, porosity, general and localized corrosion by using d.c. Potentiostate utilized for measuring the polarization curve in 3.5% NaCl solution at 250C for a single alumina layer deposited on stainless steel specimens by the dipping technique from four solutions containing different alumina concentration 0.25, 0.26, 0.61 and 0.93 mole/liter prepared by dissolving aluminum isopropoxide in water, the coats were then heat treated to 6000C. The results showed the possibility of obtaining clear protective properties that facilitate the comparison between the types of thin coatings deposited on the surfaces of the stainless steel by sol gel method.