The corrosion of austenitic 304 stainless steel in biodiesel

Fuel distribution uses 304 stainless steel containers for the storage of biofuels, however there are few reports in the literature about the corrosive aspects this. steel in biodiesel. The objective of this research is to study the corrosive behavior of 304 austenitic stainless steel in the presence of biodiesel, unwashed and washed, with aqueous solutions of citric, oxalic, acetic and ascorbic acids 0,01 mol L(-1), and compare with results obtained for the copper (ASTM D130). The employedtechniques were: atomic absorption spectrometry (AAS) and optical microscopy (OM). The results of EA A showed a low rate of corrosion for the stainless steel, the alloys elements studied were Cr, Ni and Fe, the highest rate was observed for the chrome, 1.78 ppm / day in biodiesel with or without washing. The OM of the 304 steel, when compared with that of copper has a low corrosion rate in the 304 steel/biodiesel system. Not with standing, this demonstrates that not only the 304 steel, but also the copper corrodes in biodiesel

Organic additive-copper(II) complexes as plating precursors

Cu(II) ions previously coordinated with typical electroplating organic additives were investigated as an alternative source of metal for plating bath. The coordination complexes were isolated from reaction between CuSO(4) and organic additives as ligands (oxalate ion, ethylenediamine or imidazole). Deposits over 1010 steel were successfully obtained from electroplated baths using the complexes without any addition of free additives, at pH = 4.5 (H(2)SO(4)/Na(2)SO(4)). These deposits showed better morphologies than deposits obtained from CuSO(4) solution either in the absence or presence of oxalate ion as additive (40 mmol L(-1)), at pH = 4.5 (H(2)SO(4)/Na(2)SO(4))It is suggestive that the starting metal plating coordinated with additives influences the electrode position processes, providing deposits with corrosion potentials shifted over + 200 mV in 0.5 mol L(-1) NaCl (1 mV s(-1)). The resistance against corrosion is sensitive to the type of additive-complex used as precursor. The complex with ethylenediamine presented the best deposit results with the lowest pitting potential (-0.27 V vs 3.0 mol L(-1) CE). It was concluded that the addition of free additives to the electrodeposition baths is not necessary when working with previously coordinated additives. Thus, the complexes generated in ex-situ are good alternatives as plating precursors for electrodeposition bath. (C) 2009 Elsevier B.V. All rights reserved.