Advanced Coatings for Wear and Corrosion Protection: On-Demand Oral Presentations
Program Organizers: Evelina Vogli, Flame Spray Inc.; Virendra Singh, Schlumberger
Friday 8:00 AM
October 22, 2021
Room: On-Demand Room 9
Location: MS&T On Demand
Tribological Resistance and Anti-corrosive Properties of Cr-based Electrochemical Nano-composite Coatings Reinforced with Yttria Stabilised Zirconia and Carbon Nanotubes: Pragya Tripathi1; Prvan Katiyar1; Janakarajan Ramkumar1; Kantesh Balani1; 1Indian Institute of Technology
In the present work, chromium-based electrochemical coatings consisting of 3mol% yttria-stabilized zirconia nanoparticles (YSZ) and carbon nanotubes (CNT) as reinforcements were studied wear and corrosion performance. The results constitute maximum hardness of ~24 GPa, minimum scratch volume ~3.8×10-11 m3/Nm, coefficient of friction ~0.11, and highest corrosion resistance of ~3.9 KΩcm2 for Cr-YSZ-CNT. Enhanced corrosion and tribological resistance obtained through synergistic incorporation of YSZ and CNT are assigned to the presence of YSZ nanoparticles providing matrix strengthening, finer crystallite size ~15 nm, and inhibit CNT pull out. While, CNTs provide crack bridging, act as a solid lubricant, and pin the dislocations resulting in high dislocation density of the order ~ ×1015 m-2. Thus, the synergistic role of YSZ and CNT in hybrid coating (Cr-YSZ-CNT) makes it a suitable candidate coating material for protecting vital components exposed to wear conditions and corrosive media.
Electroplated Ni-MMC Coatings as a Base Coating to Improve High Temperature Corrosion Caused by Sodiumvanadates: Christoph Grimme1; Robin Kupec1; Xabier Montero1; Mathias Galetz1; 1Dechema-Forschungsinstitut
Today’s stationary turbines often run on low grade fuels to ensure economical operation. Due to high amounts of impurities in those fuels, such as vanadium and sulfur which form low melting, aggressive sodium-vanadates during combustion cause severe hot corrosion. Up to now, this type of corrosion is mitigated by adding inhibitors, soluble in the fuel. Their reaction products form thick slags on the turbine blades which have to be removed frequently, resulting in high amounts of downtimes. A novel coating solution is presented of inhibiting particles in a metallic NiAl or NiCrAl matrix. They react with the molten salt to high melting compounds to impede corrosion. A galvanic co-deposition process was developed for the coating application, which also offers an economical benefit over commonly used thermal spray coatings as well as the possibility to tailor the Ni-base MMC coating to the specific needs e.g. by combination with a CVD process.
Galvanic Corrosion of AZ31B Ultrasonically-welded with Bare and Zn-coated Steels: Jiheon Jun1; Jian Chen1; Yong Chae Lim1; Michael Brady1; Donovan Leonard1; Zhili Feng1; 1Oak Ridge National Laboratory
Magnesium alloys, which are of great interest for light-weight structural components, are highly susceptible to galvanic corrosion when joined with other metals. This work investigated galvanic corrosion of ultrasonic spot welded (USW) AZ31B and dual-phase steels with and without Zn coating in a lap joint configuration. The USW specimens were exposed in 0.1 M NaCl with specific tape-masking schemes to produce measurable corrosion depths on AZ31B in the near weld region. The corrosion depths of AZ31B were smaller when joined with Zn-coated steels than bare steel, indicating galvanic corrosion decreased by Zn coating on the steel. Corrosion potential measured during NaCl solution immersion was more noble in AZ31B welded with Zn-removed (bare) steel, implying greater galvanic polarization for AZ31B. This agreed with the larger corrosion depth of AZ31B joined with bare steel. Bonding strength change of post-corrosion specimens assessed by lap shear tensile testing will also be presented.