02412nam a2200205 4500 376012 376012 20151020u y0pory50 ba eng Revealing obliterated engraved marks on high strength aluminium alloy (AA7010) surfaces by etching technique Recurso eletrónico Yeu Uei Bong, R. Kuppuswamy (*). Resumo inserto na publicação. Ficheiro de 654 KB em formato PDF (7 p.). Restoration 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. February 2010 Vol. 195, n. 1-3 Forensic Science International 0379-0738 p. 86-92 MARCAÇÃO DE OBJECTOS QUÍMICA FORENSE IDENTIFICAÇÃO DE OBJECTOS BONG Yeu Uei KUPPUSWAMY R. 0 PJ_04_010000000000000__ARTIGOS_DIGITALIZADOS 2022-06-06 403793 PJ PJ PJ04.01 - Artigos digitalizados 2022-06-06 0 AP