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100			_a20151020u y0pory50 ba
101			_aeng
200			_aRevealing obliterated engraved marks on high strength aluminium alloy (AA7010) surfaces by etching technique _bRecurso eletrónico _fYeu Uei Bong, R. Kuppuswamy
311			_a(*). Resumo inserto na publicação. Ficheiro de 654 KB em formato PDF (7 p.).
330			_aRestoration of obliterated engraved marks on high strength Al Zn–Mg–Cu alloy (AA7010) surfaces by etching technique was studied. The alloy surfaces weremechanically engraved with some identification marks using ‘‘Gravograph’’. The marks were then erased by removing the metal to different levels up to and below the depth of engraving. Five metallographic reagents were tested on the obliterated surfaces by etching. The following two methods (i) immersion in 10% aq. phosphoric acid and (ii) alternate swabbing of 60% HCl and 40% NaOH were found to be quite effective to reveal the obliterated marks. These two procedures were also able to show effectively the marks obliterated by over-engraving and centre punching. Of the two techniques immersion in phosphoric acid provided more contrast. Interestingly, alternate swabbing of 60% HCl and 40% NaOH presented itself to be the common reagent for restoration on pure aluminium as well as its alloy surfaces. This is evident from our own current experiments and those of earlier researchers [G. Peeler, S. Gutowski, H. Wrobel, G. Dower, The restoration of impressed characters on aluminium alloy motor cycle frames, J. Forensic Ident. 58 (1) (2008) 27–32; M. Izhar M. Baharum, R. Kuppuswamy, A.A. Rahman, Restoration of engraved marks on aluminium surfaces by etching technique, Forensic Sci. Int. 177 (2008) 221–227]. The findings have assumed importance as engines and chassis of cars and frames of firearms are currently made of high strength aluminium alloys and recovery on these surfaces by current methods is not satisfactory.
461			_dFebruary 2010 _vVol. 195, n. 1-3 _tForensic Science International _x0379-0738 _pp. 86-92
606			_aMARCAÇÃO DE OBJECTOS _9343973
606			_aQUÍMICA FORENSE _9343048
606			_aIDENTIFICAÇÃO DE OBJECTOS _9344131
700			_aBONG _bYeu Uei _9350458
701			_aKUPPUSWAMY _bR. _9344647