Question

6) Pilling-Bedford ratio is the volume of corrosion product divided by the volume of reacted metal. In a corrosion experiment 10 mg of metal reacts and converts to corrosion product coating the metal sample. The corrosion product is not soluble in electrolyte and all of it remains on the surface of the sample. The weight gain of the sample is 2 mg. The metal and corrosion product densities are given as 5 and 8 g/cm, respectively. Compute the Pilling-Bedford ratio. Is the corrosion product protective? (3 pts)

Answer 1

Given, Mass of Reacted metal, me Weight gain of the sample = 2 mg Let Mass of the CosA0sion paoduct be me 2 - m Velume of Cosnsion põadut P:1lingBedfosd Ratio Vo lme of seted met) P-B Ratio = Me ea ec grven density ot metal, le = 5 9/cm2 . density of Cosgaosion paoduct, = 9/e /2 P-B Ratio =o.75 4 P-B Ratio Since, P-B Ratio < I The Cogsosion paoduť is Non paotective