Microstructural and Mechanical Properties Analysis of Phosphate Layers Deposited on Steel Rebars for Civil Constructions

Abstract

This paper carries out a study on the microstructural characteristics and mechanical properties of phosphate layers deposited on steel reinforcements for civil constructions. Analyses were performed on 4 sets of samples: 1 control sample (unphosphated) and 2–4 samples that were phosphated with three different solutions. The structural and chemical analysis, as well as the examination of the mechanical properties (surface roughness, microindentation, and scratch resistance) of the phosphate layers deposited on steel rebars for civil constructions, was carried out. The following conclusions were drawn from the experimental results: the coatings show flashes of crystals deposited on the metal surface; chemical homogenization of the phosphated layers is observed; the profiles present a higher roughness after deposition of the phosphated layers; the indentation Young modulus and hardness values recommend the phosphating procedure to improve the CS surface quality; the COF is three times larger for phosphated samples compared with the initial metallic one; and scratch traces are uninterrupted, except for one zone of sample that was phosphated with solution II, wherein the phosphated layer does not present lateral scratches or exfoliations.