STUDY OF THE CORROSIVE EFFECTS OF DIESEL AND BIODIESEL ON GRAY CAST IRON

Abstract

Gray  cast  iron  is  a  material  used  in  the  fuel  industry  by  its  low  cost,  high  mechanical  strength  and  its  manufacturing process.  It  has  poor  chemical  resistance  due  to  its  high  reactivity  and  susceptibility  to  corrosion.  The  use  of  biodiesel creates challenges of compatibility for this material, due to its oxidation and high hygroscopicity, which act as accelerators of  corrosive  processes.  Within  the  applications  this  material  has  to  offer,  there  are  conditions  of  high  temperature  and pressure that affect the interaction  with biodiesel and its process of corrosion. Gray cast iron samples  were subjected to contact  with  palm  biodiesel  using  the  technique  of  static  immersion  in  ambient  conditions  (18°C)  and  thermal  cycles (Cyclic oxidation since18 to 200°C) and the corrosive effects were quantified. The material was immersed for a period of 450 hours and its weight was periodically recorded until the end of the test. The surface of the material was also analyzed by optical microscopy, scanning electron microscopy and x-ray diffraction. The results indicated a greater rate of corrosion on the cast iron for biodiesel fuel compared to regular diesel. In addition, it was observed that the thermal cycles accelerate the corrosive processes up to 4 times with respect to the ambient temperature.