Effect of Triazine Dithiols on the Polymer Plating of Magnesium Alloys

Abstract

2- Substituted (R)-1,3,5- triazine-4,6-dithiols (triazine dithiols ) with different alkyl chain lengths as substituents were prepared by the reaction of cyanuric chloride, dialkylamines and NaSH. Triazine dithiols were found to polymerize electrochemically on magnesium alloy (AZ91) plates. This method for coating metals is called polymer plating In the polymer plating of triazine dithiols on magnesium alloy plates, an aqueous 1M-NaOH solution was selected for the formation of polymer films and the suppression of side reactions. To select the optimal conditions for the formation of polymer films and the suppression of side reactions, plating factors such as the electrolyte, temperature, concentration, potential and current density were investigated. The films formed were composed of a polymer film, Mg(OH)2 and MgO, and the chemical structure of the films is discussed. The contact angle of the polymer films increased with the length of the alkyl chain and became constant for a chain length of six carbons. Polymer films with a 98° contact angle had a top surface completely covered all by CH3 - groups and not by - CH2- The alkyl chains were oriented in the vertical direction and were closely packed. Among the five polymer films studied real impedance (Rp) was the largest at about 27,000 Ω cm -2 - for the polymer film with a (C6H13)2N- subustituent The icorr of this polymer film was 5x 10 -7 A cm -2 2 The outstanding corrosion resistance of polymer film with a (C6H13)2N-subustituent is thought to result from the alkyl chains in the film that were highly oriented and closely packed.