Substrate Protection for Corrosion Prevention: Substrate Protection for Corrosion Prevention II
Program Organizers: Mary Lyn Lim, PPG Industries; Cortney Chalifoux, Exponent; Qixin Zhou, The University of Akron; Kylee Fazende, NSWC Carderock Division; Raul Rebak, GE Global Research; Tushar Borkar, Cleveland State University
Monday 2:00 PM
November 2, 2020
Room: Virtual Meeting Room 27
Location: MS&T Virtual
Session Chair: Mary Lyn Lim, PPG Industries; Qixin Zhou, University of Akron
2:00 PM
Corrosion Resistant Coatings on 6061 Aluminum: Jing Xu1; Rajeswaran Radhakrishnan1; Cory Crowley2; Timothy Hall1; Jennings Taylor1; Maria Inman1; Stephen Snyder1; 1Faraday Technology Inc; 2Fermi National Lab
Faraday will describe our recent work on the development of corrosion resistant coatings directly applied to aluminum (6061) after one-step electrochemical surface pretreatment process. Conventional aluminum coating application processes commonly require extensive surface pretreatment processes prior to deposition, owing to aluminum’s reactive nature and affinity for oxygen. In this study we will discuss a simple pretreatment process that enables direct deposition onto Al alloys and can dramatically reduce the cost and challenges associated with the surface preparation of Al. Furthermore, we will discuss the corrosion performance of the Ni, NiP, and ZnNi coatings applied directly to 6061 Al surfaces.
2:20 PM
Effect of Surface Coating and PTFE Tape Insulation on Galvanic Corrosion of AZ31B Bolt-joined with CFRP: Charles Warren1; Jiheon Jun1; Yong Chae Lim1; Zhili Feng1; 1Oak Ridge National Laboratory
Magnesium (Mg) alloys and carbon fiber reinforced polymer (CFRP) are of high interest for lightweight vehicles. Although bolting can achieve reliable joints for multi-materials auto-body structures, galvanic corrosion of Mg in contact with CFRP and steel bolt is a great concern. To mitigate galvanic corrosion, electrical isolation between Mg, CFRP and bolt was attempted. In this work, bolted specimens of AZ31B and CFRP were prepared with and without surface coating between AZ31B and CFRP. Polytetrafluoroethylene tape applied on the steel bolt as an insulation layer. Then, the bolted specimens were tested by 0.1M NaCl immersion and ASTM B117. Corrosion potential of the bolted samples with isolation in 0.1M NaCl was closer to Mg corrosion potential, suggesting weaker galvanic polarization. The corrosion depth measured on AZ31B in the joints was significantly smaller with isolation case. Lap shear tensile testing of the post-corrosion specimens with isolation showed less degradation of joint strength.
2:40 PM Cancelled
Improving the Corrosion Performance of Carbide-reinforced Martensitic Steels via Adding Trace Cu: Kenta Yamanaka1; Chen Zhang1; Manami Mori2; Huakang Bian1; Akihiko Chiba1; 1Tohoku University; 2National Institute of Technology, Sendai College
Carbide-reinforced martensitic steels have been used as tool materials in various industries because of their high hardness and excellent wear resistance. Nonetheless, such steels show severe degradation when used in a corrosive environment because Cr2O3 films do not often work as passive layers. Here, we demonstrate a significant improvement of the corrosion performance of a high-carbon-containing Fe-Cr-W-based alloy in a sulfuric acid solution by adding trace Cu. The Cu enrichment at the surface of the alloy as corrosion proceeds was found to inhibit further corrosion. The corrosion behavior is also sensitive to the Cr content of the alloy and depends on the annealing temperature prior to quenching. We developed a theoretical corrosion model for the current alloys by considering a micro corrosion cell, which considers a potential difference between the carbide precipitates and the surrounding matrix, and applied it for interpreting the experimental observations.