الفهرس 
Chapter One: IntroductionOnly 14 pages are availabe for public view
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Abstract
Polyurethane composites have received considerable research attention in the last decades owing to their remarkable improved tribological characteristics. The present work discusses the possibility of coating steel sheets by polyurethane reinforced by copper, steel and nickel chrome wires. The abrasion resistance of polyurethane coatings of steel sheets has been investigated. The tested polyurethane composite coatings are proposed to decrease erosion wear of buildings and defeat sand erosion during dusty storms. Experiments have been carried out using sand blast test rig. The tests were carried out at test specimens of steel sheets of 120 × 100 × 2 mm are coated by polyurethane and reinforced by metal wires of 0.4, 0.5 and 0.6 mm diameter. The test specimens are sand blasted at 90° and the wear is evaluated by the weight loss after test. Two types of wire directions are used; unidirectional continuous and grid. The distance between wires is 2, 4and 6 mm. we have 18 samples in each diameter, 9 in the vertical direction and 9 in the grid direction, and the distance between wire 2mm ,4mm and 6mm. and we have Polyurethane thickness. 0.2mm coating thickness, 0.5 mm coating thickness and 0.7mm coating thickness. The material of wires is copper, steel and Ni Cr. The tests were carried out using sand particles grain size 0:1000μm, distance between specimen and nozzle L = 80 mm. compressor output pressure = 8 bar. the test carried out during 3 min. Based on the experimental results, it was found that, wear of polyurethane coatings reinforced by copper wires decreases drastically down to minimum at 0.5 mm wire diameter then slightly increases with increasing wire diameter. The minimum value of wear is observed for coating of 0.7 mm coating thickness. The erosion caused plastic deformation of the copper wire. Grid reinforcement of copper displays lower wear than that observed for longitudinal wires. Wear of coatings reinforced by steel wires decreases drastically with increasing wire diameter. Resistance of the composites reinforced by steel wires is higher than that observed for copper wires. The minimum value of wear is observed when the substrate is coated by 0.5 mm coating thickness of polyurethane. The minimum value of wear of composites reinforced by stainless steel (Ni Cr) wires is observed for test specimens coated by 0.5 mm coating thickness of polyurethane. Gridded Ni Cr wires of 0.6 mm diameter shows the minimum wear. Evidence of wear of polyurethane coating reinforced by Ni Cr wires confirms the weak cohesion of wires in the coating matrix.
Erosion wear decreased with decreased distance between wires, wires strengthened the eroded area, as the coating thickness increased wear decreased, when decreased distance between wires increased bonding force and increased adhesion area, and consequently wear decreased. Generally, the steel wires strengthened the eroded area and increased bonding force and consequently polyurethane accumulation around the wires, therefore wear decreased and resistance of specimen increased to wear.