Advanced Materials and Processes Research Institute
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Effect of Cr(VI)-Fe (II) interaction on the corrosion resistances of iron at different Ph in dichromate solutions
No full textEffect of Cr(VI) - Fe(II) interaction on the corrosion resistance of iron in dichromate solutions has been studied under different experimental conditions. The presence of dissolved oxygen (DO) in the solution decreases Cr(VI) reduction by Fe(II) at pH 4 which became quite noticeable at pH 7. This probably influences corrosion of iron to certain extent. A positive shift of OCP and measurements of a higher charge transfer resistances of iron in dichromate solution of pH 2 and 3 suggest the formation of a protective film on iron. Energy Dispersive X-ray Analysis (EDXA) of iron immersed in Cr(VI) solution indicated a greater involvement of chromium in the formation of a protective film at iron surface. On the other hand, the EDXA analysis showed a decrease in chromium concentration in the reaction product film on the immersed iron surfaces in Cr(VI) solution at pH 4 and above. A shift of OCP in the negative direction and the occurrence of lower charge transfer resistance at the above pH as compared to pH 2 and 3 is attributed to a decrease in the protective properties of the film.\u
SiC particulate dispersed composites of an Al–Zn–Mg–Cu alloy:\ud Property comparison with parent alloy
No full textComposites have been formed by adding 15 wt.% of SiC dispersoids in the size range of 20–40 Am to Al–Zn–Mg–Cu alloy (corresponding to the 7075 series). The 7075 aluminium alloy and composites have been subjected to heat treatment in an attempt to optimize their properties. The present paper reports the improvement in the hardness, mechanical and sliding wear resistance properties attained as a result of heat treatment and forming composites. An attempt is made in the paper to understand the mechanism responsible for the improved behaviour of the 7075/SiC aluminium composite over the base alloy\ud
through microscopic/metallographic analysi
Rapid determination of sulfonamides in millk using micellar electrokinetic chromatography with fluorescence detection.
No full textA new method was developed for the determination of sulfonamides in milk by using micellar electrokinetic chromatography coupled with fluorescence detection. Separation of fluorescamine-derivatized sulfonamides was accomplished by using a buffer 13.32 mM disodium hydrogen phosphate, 6.67 mM potassium dihydrogen phosphate and 40 mM sodium dodecyl sulphate at pH 7.5 in addition to positive power supply at 21 kV at 25 °C. Detection was performed using UG-11 excitation filter and 495 nm emission filters. The proposed capillary electrophoresis method allows the separation of five sulfonamides within 7 min with a limit of detection of 1.59–7.68 nmol/L for all the sulfonamides considered for present study. A simple sample preparation method with fairly good recoveries 85–114% is also presented in current paper. Inter-day and intra-day validation of the separation method shows fairly good results. Robustness of the method has also been studied
Graphite–Epoxy Graded Material by Centrifugation
No full textA graded distribution of graphite particles in\ud
epoxy resin matrix was obtained using a centrifugation technique.\ud
By varying the centrifugation time the graded profile\ud
could be effectively controlled. Scanning electron microscopy\ud
and optical microscopy revealed the graded dispersion\ud
of graphite particles in the epoxy matrix, which is sensitive\ud
to centrifugation time. Electrical or wear properties can accurately\ud
estimate the property profile of graded material.\ud
The abrasive wear test also provided a quick estimation of\ud
the extent of gradient formed in the sample. The increased\ud
centrifugation time increased the compaction of graphite\ud
particles in the graphite-rich phase of graded material that\ud
could be correlated with the increased capacitance of the\ud
sample
Effectiveness of an Externally Added Solid Lubricant on the Sliding Wear Response of a Zinc–Aluminium Alloy, Its Composite and Cast Iron
No full textEffect of addition of talc on the sintering characteristics of fly ash based ceramic tiles
No full textThe sintering characteristics of fly ash–talc mixtures having 0–100% talc (w/w) in the presence of 10% (w/w) sodium hexa meta phosphate (SHMP) have been studied. In the fly ash rich mixtures, the presence of needle shaped mullite and rhombohedral aluminum phosphate phases is responsible for providing impact strength to sintered tile bodies. On gradual addition of talc, the decrease in the concentration of sillimanite and increase in the concentration of sodium magnesium phosphate crystals is responsible for the observed improvement in the impact strength of tiles. With increase in talc content, initially the % water absorption decreases to reach a minimum for a fly ash–talc mix containing 60% (w/w talc) where after it again starts increasing. The apparent density of the tile samples increases with increasing talc content in the raw mix due to densification as well as higher density of talc as compared to fly ash
Fast seperation and sensitive detection of carcinogenic aromatic amines by reversed phase liquid chromatography coupled with electrochemical detection.
No full textA micro-LC method was developed for the fast and sensitive analysis of aromatic amines by electrochemical detection. The chromatographic separation of nine carcinogenic aromatic amines was performed on an ABZ + PLUS column with detection limits up to pM L(-1) levels. Mobile phase comprised of methanol-acetate buffer of pH 5 (45:55, v/v) used at a flow rate of 0.2 ml min(-1). The detection was performed with a 6 mm glassy carbon electrode at an applied potential of 0.8 V versus Ag/AgCl. An intraday RSD for retention time and peak area were between 0.22% and 0.73% and 1.86% and 4.03%, respectively. The interdays RSD for retention time and peak area were between 0.47% and 1.35% and 2.04% and 4.42%, respectively. The applicability of the assay has been demonstrated by analyzing these aromatic amines in lake water and synthetic food colour additives. A comparison is given between electrochemical and UV detection
Effect of zinc concentration and experimental parameters on high stress abrasive wear behaviour of A1-Zn alloys: A factorial design approach.
No full textHigh stress abrasive wear behaviour of Al–Zn alloys containing high zinc concentration at varying applied load and abrasive size has been studied through two-level full factorial design approach. The upper level of zinc concentration, applied load and abrasive size is selected as 70 wt%, 7 N and 180 μm, respectively. The lower level of zinc concentration, applied load and abrasive size is taken as 30 wt%, 1 N and 60 μm, respectively. The linear regression equation, for the wear rate (Wr) as a function of these parameters (applied load, abrasive size and Zn-concentration) and their interaction, has been developed as:\ud
\ud
Wr=17.34+1.81C+12.23L+3.27A+1.27CL+3.36LA+1.68CA+1.14CLA\ud
Turn MathJax on\ud
\ud
where C, L and A are coded values of Zn-concentration, applied load and abrasive size, respectively, and the multiplication factor for the wear rate and the coefficients is 10−11 m3/m. The positive value of the coefficients associated with coded values of various parameters and their interactions in the above equation suggests that abrasive wear rate increases with zinc concentration, abrasive size and applied load. The validity of the developed equation has been checked with experimental values at randomly selected experimental parameters within the selected experimental domain. The results have been explained with selected worn surfaces and debris analysis
Erosion-Corrosion Behavior of SiC Particle-Reinforced A1-Si Alloy in NaOH Slurry.
No full textThe erosion-corrsosion behavior of SiC particle-reinforced Al-Si alloy has been studied in NaOH slurry simulating the mining atmosphere. The study was performed at two different sand concentrations, namely, 20 and 30 wt pct, and at a speed of 900 rpm. It is depicted that the wear rates decreased with increasing sand content, indicating that corrosion is the dominating mode of material removal. Further composite exhibited lower wear resistance than the laloys irrespective of the sand concentration. Scanning electron microscope (SEM) observations indicated the dissolution of dendrites of Al due to severe corrosion, leaving behind the network of Si. This ultimately results in the falling of Si particles from the matrix, leaving behind voids. This also results in the formation of voids around the SiC particles and leads to pullout of SiC particles from the matrix during the wear process
