Girija Suresh

Investigation of the thermal conductivity of selected compounds of gadolinium and lanthanum

Abstract As a part of the development of rare earth based ceramic materials for nuclear applications, the thermal conductivity of gadolinium zirconate, lanthanum zirconate and gadolinium aluminate was investigated employing the laser flash technique and covering a temperature range from 650 to 1400 K. Based on the temperature dependence of the thermal resistivity, the heat transport behaviour of these materials was briefly examined.

Investigation of the thermal conductivity of selected compounds of lanthanum, samarium and europium

Abstract As part of the development of rare earth based ceramic materials for a variety of applications, the thermal conductivities of lanthanum aluminate, samarium zirconate and europium zirconate were investigated, employing the laser flash technique and covering a temperature range from 650–1400 K. Based on the variation of the thermal resistivity as a function of temperature, the heat transport behaviour of these materials was briefly examined.

Corrosion assessment of type 304L stainless steel in nitric acid

Abstract AISI type 304L stainless steel (SS) was assessed for its corrosion resistance in nitric acid solution. The effect of variation in nitric acid concentration (1 to 10N) and temperature (298 K, 313 K, 333 K, 348 K) on the corrosion resistance of 304L SS was investigated using potentiodynamic polarisation studies. The corrosion resistance of the alloy was also studied in 1N nitric acid containing different concentrations of chloride ion (1000, 5000, and 10 000 ppm) in order to understand the tendency to pitting corrosion. The results show that the corrosion resistance of the material deteriorated for acid concentrations greater than 4N. The temperature of the acid was found to have a profound effect on the corrosion resistance, with corrosion becoming more prominent at temperatures of 333 K and above. Chloride ions up to a concentration of 10 000 ppm were found to have no effect on the pitting resistance of the material studied.

Electrochemical Noise Analysis of Pitting Corrosion of Type 304L Stainless Steel

Electrochemical current and potential noise were simultaneously acquired from Type 304L stainless steel (UNS S30403) in 0.05 M ferric chloride (FeCl3) using a three-electrode configuration. Power spectral, statistical, and wavelet analyses have been used to know the uniqueness of the parameters proposed for the identification of various types of corrosion processes. Roll-off slopes derived from power spectral analysis and statistical parameters such as standard deviation, localization index, and kurtosis corroborated with pitting as the corrosion mechanism. Energy distribution plots (EDP) obtained from wavelet analysis of current noise was found to be useful to derive mechanistic information on the progress of corrosion. Discrete wavelet transform was used to decompose the signals into a D1, D2, D3…D8, S8 set of coefficients. The EDP showed that the contribution from the medium time scale crystal, D5, prevailed over the smaller time scale crystals and larger time scale crystals during the initial stages o...

ELECTROCHEMICAL NOISE TECHNIQUE FOR CORROSION ASSESSMENT - A REVIEW

This review details the electrochemical noise technique as applicable to corrosion assessment with emphasis on the fundamental principles, theoretical aspects, data analysis and applications. The use of this technique in understanding the mechanistic aspects of corrosion and corrosion monitoring has been discussed. The important applications of this technique in corrosion processes like uniform corrosion, localized corrosion (pitting, crevice corrosion and stress corrosion cracking), and evaluation of coatings are highligted. Miscellaneous applications are also explained.

Investigation of the Thermal Conductivity of Selected Rare Earth Aluminates

As a part of the thermophysical property studies on rare earth based oxide ceramics thermal conductivity of the aluminates of samarium and dysprosium was investigated employing laser flash technique and covering a temperature range from 673 to 1373 K. Heat transport behaviour was briefly examined by analysing the variation of thermal resistivity as a function of temperature.

Effect of Laser Surface Melting on the Microstructure and Pitting Corrosion Resistance of 304L SS Weldment

The manuscript presents the effect of laser surface melting (LSM) on the microstructural variations and pitting corrosion resistance of 304L SS weldment fabricated by gas tungsten arc welding of 304L SS plates using 308L SS filler wire. The weld region was examined by X-ray radiography for defect detection. LSM of 304L SS weldment was performed using Nd:YAG pulsed laser. Microstructural evaluation was carried out using optical and electron back scatter diffraction techniques. The microstructure of 304L SS base was found to be austenitic, while the weld region of 304L SS weldment contained delta ferrite distributed in austenite matrix. The microstructure of LSM 304L SS weldment was found to be homogeneous austenite matrix with sparsely distributed ferrite. Ferrite measurements showed a decrease in the percentage ferrite in the fusion zone of 304L SS weldment after LSM. A profound enhancement in the pitting corrosion resistance was observed after LSM, which could be attributed to the homogeneous microstructure and decrease in the ferrite content. Pit density was found to be higher in the heat-affected zone of the weldment. Very few pits were observed in the LSM 304L SS weldment compared to the as-weldment.