الفهرس 
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Abstract
Thermal spraying is designed to produce surface coatings of a wide range of materials . including metals, alloys, oxide, ceramics and cermets. Originally known as metal spraying, the process derives its name from the fact that the material being deposited is passed .through a heat source, and molten particles are projected to the prepared work surface to form an :adherent and cohesive coating. Thermal spraying is used extensively. in the manufacture of original equipment components: It finds a wide use both manufacturing and-maintenance applications. The thermal spraying technique .used in this study is the powder flame spraying. In this process, the spraying material. in a powder form is fed into and melted by oxyacetylene flame and propelled onto the substrate by the force of combustion gases. In . this work, different substrate types, spraying powder types, substrate preheat . Temperature and spraying time were studied. The surfaces were also polished using emery SiC papers with different grits to study the effect of the surface roughness on the coating characteristics. Coating the substrates in a multilayer technique was also investigated. The study of the effect of the variables mentioned above on the behavior of each element of the two used alloys powder (10185 - 10112) in the coating layer was made using SEM attached with EDAX unit. .The obtained results ware clarified with graphical charts. Also. the study of the effect of some studied variables on the microstructure of the coating layer had made, The cleaned and de greased low carbon steel samples were preheated to 200 °C,400 °c and 600°C. Un preheated and preheated samples were sprayed with Eutalloy 10185 powder. It was found that the substrate has to be preheated to at least 200°C to obtain. adhesive coating layer. It was noticed that the coating layer thickness decreases with increasing substrate preheat temperature. Increasing preheat temperature leads to an increase in nickel diffusion the coating layer. Investigating the coated layers detected.