The Preparation of the Chromized Coatings on AISI 1045 Carbon Steel Plate with the Electroplating Pretreatment of Ni or Ni/Cr-C Film

Abstract

Chromized coatings on AISI 1045 steel were prepared as bipolar plates for proton exchange membrane fuel cells (PEMFCs) by low-temperature pack chromization. Before pack chromization, two kinds of pretreatment processes including the Ni electroplating and the Ni electroplating, followed by Cr-C electroplating were used to activate the steel surface. The additional Cr-C electroplating promotes the chromization rate, resulting in a thicker chromized coating (1045-Ni-CrC-Cr(700-2)) with higher carbides and nitrides contents. The 1045-Ni-CrC-Cr(700-2) specimen shows the lowest corrosion current density, 8.37×10-8 Acm-2, and the smallest interfacial contact resistance, 14 mΩ-cm2, at 140 Ncm−2 among all tested steels. The 1045-Ni-CrC-Cr(700-2) specimen also had high surface energy. The contact angle of the 1045-Ni-CrC-Cr(700-2) with water was about 100°, which is beneficial for water management in a fuel cell. This study clearly indicates that the additional Cr-C electroplating pretreatment step can improve the properties of chromized 1045 steel tremendously, which possess the potential to be bipolar plates in the application of PEMFC.