Renovation of Crystallizer Surface Using Electrodeposited Alloy Coating to Increase High-Temperature Abrasion Resistance

This paper deals with the evaluation of mechanical and tribological properties of Ni-Co galvanic coatings at elevated temperatures. The coatings were deposited on the copper surface, which in practice is the material of the crystallizer. Ni-Co coatings are manufactured to increase the abrasion resistance of the crystallizer surface at elevated operating temperatures. The microhardness (HV0.05) measurements of the coating at 400 °C were used to determine its mechanical properties. The Ball-on-Disc Test was used to determine the tribological properties of the coatings at 400 °C. The mechanical and tribological properties of Ni-Co coatings at elevated temperature were compared to the results of experiments performed at room temperature. When heated to 400 °C, HV0.05 decreased by 9.5 to 22% (depending on Co content in the coating) compared to the values that were measured at 23 °C. The change in the COF for the Ni-Co coating at 400 °C was from 0.680 to 0.750 depending on the Co amount compared to the values at 23 °C. The COF values at room temperature ranged from 0.373 to 0.451. The places with higher wt. % Co had better friction properties than the places with lower wt. % Co.

The Electrodeposition of Ni-Fe-Cr Alloy Coatings on Mild Steel Surfaces and Evaluation of Corrosion Resistance

The electrodeposition of Ni-Fe-Cr alloys was investigated in a trivalent chromium electrolyte on the surface of mild steel over a range of current density. Scanning Electron Microscopy (SEM), Tafel plot and Electrochemical Impedance Spectroscopy (EIS) measurements were used to compare plated alloy coatings and heat-treated electrodeposited alloy coatings. The heat-treated alloy coatings showed a relatively large impedance values and corrosion inhibiting efficiency. Moreover, the polarisation resistance, Rp, was obtained by EIS modeling using equivalent circuits.