Analisa Pengaruh Material Abrasif Pada Blasting Terhadap Kekuatan Lekat Cat dan Ketahanan Korosi di Lingkungan Air Laut

Abstract

Coating is a covering that is applied to the surface of an object, usually referred to as the substrate. Commonly, coating is used in the industry because it is more economical and easier to used. However, this technique is also has a lot of problems. Problems arise from these techniques due to poor surface preparation process that can reduce the adhesion of paint. A poor surface preparation process can be caused by various things including a mesh size of abrasive material, abrasive material selection, and human errors. This research was conducted to analyze the effect of abrasive material for blasting against the adhesive strength of the paint in ASTM A36 which was blasted with varying abrasive material i.e aluminum oxide, steel grit, and volcanic sand, and was coated with different paint types i.e epoxy paint and zinc rich paint. The results showed that the increasing of abrasive material hardness can increase the surface roughness. And increasing surface roughness will increase adhesion of paint to the substrate, which will improve the corrosion resistance of the material. The highest surface roughness value , 84.71 µm, and the highest adhesion value in specimens which coated with epoxy paint and zinc rich paint, consecutively 20.04 MPa and 21.46 MPa possessed by the specimens which use steel grit as an abrasive material for blasting. The results of salt spray testing with NaCl 5% for 72 hours, and 168 hours on the specimens shows that specimens which blasted with steel grit still has the highest adhesion values. The highest adhesion value after the salt spray test for 72 hours in specimens which coated with epoxy paint and zinc rich paint, consecutively 14.15 MPa and 15.05 Mpa. While the highest adhesion value after the test salt spray for 168 hours on the material in the coating with epoxy paint and zinc rich painted consecutively 11.91 MPa and 12.80 MPa.