Characterization of Sherardized Low Carbon Steel Used in Oil Pipelines Coated with Polymer Blends Layers


Oil pipelines of low carbon steel were coated by sherardizing process at 400oC for different treatment times (15, 30, 60, 120, 240) min and then the sherardizing samples coated by polymer blend unsaturation polyester resin with butadiene rubber (UP: BR) and unsaturation polyester resin with nitrile butadiene rubber (UP: NBR) with different percentage weight ratio of BR and NBR (0, 5, 10 and 15 %) in the blends. The thickness of sherardizing coated, hardness, surface roughness and adhesive strength were studied. The results of this research showed that the thickness of sherardizing coated and hardness values increase with increasing time treatment. The adhesive strength of sherardizing surface coated with polymer blends layer increases with increasing surface roughness of sherardizing coated with two mixed group of polymers blends [(UP:BR) and (UP:NBR)] samples, as well as the adhesive strength decreases with increasing percentages weight of BR or NBR in the blend. The higher values of adhesion force reach to (2.761KN) and (0.848KN) for polymer blends (95%UP: 5%NBR) and (95%UP:5%BR) respectively. Whereas coating sherardizing surface by unsaturated polyester only has the high value of the adhesion force (2.921 KN) at surface roughness (2.29µm). As well as the results show the sherardizing surface coated by mixed polymers blend (UP: NBR) having higher values of adhesion force compared with other samples coated by mixed (UP: BR) polymer blend.