Showing 2 results for Oxalic Acid
Moayed M.h.,
Volume 2, Issue 3 (9-2005)
Abstract
In this research pitting Corrosion of a sensitized 316 stainless steel was investigated employing potentiodynamic, potentiostatic techniques. Sensitization process was carried out on as-received alloy by submitting the specimen in electric furnace set at 650°Cfor five hours and then the specimen was quenched 25°C water. Potentiodynamic polarization of as received and sensitized specimens in 1M H2SO4 solution at room temperature and 70°C clearly revealed that the sensitization process has caused a magnificent change on electrochemical behavior of the specimen by changing critical current density for passivation, passivation potential and passive current density. Optical microscopy examination of the specimen surface after oxalic acid electrochemical etching also showed the deterioration of grain boundary of sensitized specimen due to chromium carbide precipitation in compared to as-received one. Several anodic potentiodynamic polarization on rode shaped working electrodes prepared from as-received and sensitized specimen in 3.5% NaCl test solution proved an average ~220 mV drop in pitting potential due to sensitization. Anodic potentiostatic polarization at 400 and 200 mV above corrosion potential also demonstrate the deterioration of pitting resistance of alloy as a result of sensitization. Scanning electron microscopy examination of anodically polarized of sensitized specimen at 700mVprior and after oxalic acid etching revealed large stable pits with lacy cover and also openpits with deep crevice for etched specimens.
Sh. Damghanian, H. Omidvar, S. H. Tabaian, A. R. Azadmehr,
Volume 11, Issue 2 (6-2014)
Abstract
The conical nanostructure improves the applications of alumina membranes and provides three dimensional
nanometer scale systems to study the chemical and physical properties. In this study, the nano cone structure is
produced in porous anodic alumina (PAA) by two-step anodizing. This conical nanostructure will improve the
application of PAA membranes. This approach is novel generation of the so-called "gradually decreased voltage"
technique, in which the voltage- time curve is divided into three stages and the effect of each step is investigated for
different electrolytes. The effect of the decreasing voltage is examined in two types of electrolytes oxalic and
phosphoric acid with a constant decrease in voltage rate. The results of SEM, FE-SEM images show the slope of the
inner cone layer in the oxalic acid to be considerably larger compared with phosphoric acid.
