Abstract The present work is focused on the influence of zinc trivalent plating on laser shot peened AISI 304 stainless steel samples to improve the corrosion resistance of the steel surface. AISI 304 steel samples were heat treated by annealing and polished to perform Laser Shot Peening (LSP) process using Nd-YAG laser functioning at a pulse interval of 10ns with different energies of 200 mJ, 300 mJ and 400 mJ on each sample. The highest magnitude of compressive residual stresses is induced using the pulse density of 2500 pulses/cm2. The laser treated sample was characterized by surface hardness using Vickers micro hardness test and surface morphology using an optical microscope and SEM analysis. The surface hardness of the sample is increased by increasing laser energy. The prepared zinc trivalent is plated using electro deposition on the laser treated surface by maintaining current between 1.5 to 4 amps/Dm2, and temperature between 20 to 40 deg C. MAHR’s roughness tests were performed to find the surface roughness of the sample. The surface roughness has drastically increased on zinc- coated samples compared to samples without coating. The Vickers micro hardness test conducted on zinc trivalent plated sample revealed the increase in hardness value of 200 mJ by 24% compared with 200 mJ sample without coating. SEM and EDAX were carried out to know the changes occurred in the chemical composition of the samples before and after coating.

The particle size of asphaltene flocculates has been the subject of many recent studies because of its importance in the control of deposition in petroleum production and processing. We measured the size of asphaltene flocculates in toluene and toluene - n-heptane mixtures, using the light-scattering technique. The asphaltenes had been extracted from Brazilian oil from the Campos Basin, according to British Standards Method IP-143/82. The asphaltene concentration in solution ranged between 10-6 g/ml and 10-7 g/ml. Sizes was measured for a period of about 10000 minutes at a constant temperature of 20°C. We found that the average size of the particles remained constant with time and increase with an increase in amount of n-heptane. The correlation obtained for size with concentration will be useful in asphaltene precipitation models.

We develop four identities concerning parameter differentiation of fractional powers of operators appearing in the Tsallis ensembles of quantum statistical mechanics of nonextensive systems. In the appropriate limit these reduce to the corresponding differentiation identities of exponential operators of the Gibbs ensembles of extensive systems derived by Wilcox.