Volume 36, Issue 5 (September 2008)
Analysis of Major, Minor Constituents and Various Phases in Carbon Brush by Classical Gravimetry, Titremetry, and by Instrumental Method
A new precise chemical method has been developed for the compositional analysis of carbon brush. The major chemical constituents of carbon brush are carbon (C), copper (Cu), lead (Pb), and tin (Sn), while the minor constituents are silica (SiO2), iron (Fe), and molybdenum (Mo). The analytical techniques employed for graphitic carbon, Pb, Sn, and SiO2 analysis were gravimetry (Loss in ignition, as PbSO4, as metastannic acid, and as SiO2, respectively) and titremetry for copper (Iodimetry). Trace impurities of Fe and Mo were determined by flame atomic absorption spectrometry (FAAS). On the same sample, gravimetric methods as above have been compared for Cu (as cuprous thiocyanate) by gravimetry and for Pb and Sn by normal titremetry (EDTA with xylenol orange as indicator). XRD confirmed the presence of graphitic carbon in carbon brush. The major constituents (w/w %) of carbon brush for Cu, C, Pb, Sn, and SiO2 were found to be 40.5±0.3, 39.5±0.25, 9.5±0.10, 10.2±0.13, and 0.45±0.07, respectively, and minor constituents Fe and Mo were found to be 4.2±0.21 and 1.6±0.2 mg kg−1, respectively. The titremetry Cu results obtained are comparable by gravimetry, which were 40.8±0.5. The gravimetric results obtained for Pb and Sn are comparable by titremetry and FAAS results of SiO2, which were 9.3±0.30, 10.1±0.2, and 0.25±0.09 (w/w %), respectively. The comparability of the above gravimetric and titremetry methods for various constituents are in good agreement with the methods presented in this paper for carbon brush and have been found to be reproducible within an uncertainty of 1.5 % RSD.