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100			_a20151020u y0pory50 ba
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200			_aAn investigation into the suitability of some etching reagents to restoringobliterated stamped numbers on cast iron engine blocks of cars _bRecurso eletrónico _fMohd Farizon Abdul Wahab, Nurul Izwani Mohamad Ghani, R. Kuppuswamy
311			_a(*). Resumo inserto na publicação. Ficheiro de 3,17 MB em formato PDF (11 p.).
330			_aMost of the automotive companies use cast iron for their engine blocks. Restoration of obliterated number on these iron surfaces by chemical etching is known to be quite difficult. Heating of the obliterated surface using oxyacetylene flame is an alternative recovery treatment suggested in literature and used in practice. However chemical etching has been established to be the most sensitive technique for detection of metal deformation present under stamped serial numbers. Hence, the current work investigated the suitability of some common etchants on cast iron surfaces with a view to determining the most suitable one for revealing the obliterated marks. The reagents tested were mostly copper containing Fry’s reagent and its modifications. Two cast iron engine blocks (3.29%C and 3.1%C) of two cars – a Proton Saga and a Toyota – were utilized for the experiments. The engine blocks were cut into several small plates and each plate was stamped with some numerical characters at 8 kN load using Instron Table Mounted Universal Testing Machine. The depth of stamping impression varied between 0.2 mm and 0.3 mm. The stamped number was completely ground off manually using a metal file. The grounded surface was then polished smooth using emery papers and etched with a few selected reagents mostly by swabbing. Experimental results showed that a modified Fry’s composition consisting of 45 g CuCl2, 100 mL HCl, and 180 mL H2O restored the number with better contrast at a reasonably shorter time. The above reagent is a slightly modified form of one of the Fry’s original compositions – 45 g CuCl2, 180 mL HCl, and 100 mL H2O. Quite importantly the proposed reagent restored the original stamped numbers of both Proton and Toyota cars and also a Mitsubishi car that hadbeen obliterated. The most widely used Fry’s composition (90 g CuCl2, 120 mL HCl and 100 mL H2O), although recovered the obliterated number, did not cause the desired contrast.
461			_dNovember 2012 _vVol. 223, n. 1-3 _tForensic Science International _x0379-0738 _pp. 53-63
606			_aVEÍCULO AUTOMÓVEL _9241256
606			_aMARCAÇÃO DE OBJECTOS _9343973
606			_aANÁLISE LABORATORIAL _9326721
606			_aESTUDO DE CASOS _9322367
606			_aQUÍMICA FORENSE _9343048
700			_aWAHAB _bMohd Farizon Abdul _9350454
701			_aGHANI _bNurul Izwani _9350455
701			_aKUPPUSWAMY _bR. _9344647