金属物体高温熔融形态特征检验

Morphological Characteristics of Metal Object Formed with High Temperature and Their Forensic Applications

金属等固态物质在高温下可发生熔融。由于表面张力的作用,熔融物在冷却过程中会形成球形、近似球形的颗粒,或者在较大的金属物体的表面形成融化状痕迹。在法庭科学领域,由于爆炸、纵火、电击、枪击等类案件中一般都会出现局部或一定范围的高温现象,因而相关物证表面熔痕的检验以及现场提取的熔融状残留物检验,对案件的侦破具有十分重要的意义。另外,焊接、切割等金属加工产生的熔融状金属微粒,对于推断嫌疑人职业特征也可提供重要依据。目前我国法庭科学微量物证检验多以化学成分检验为主,对形态检验重视不够,有些甚至完全忽视了形态检验。本文对射击残留物、电流斑金属颗粒、焊渣、砂轮切割金属碎屑的检验方法进行了总结,对微观形态的形成机制和证据价值进行了分析,并针对我国当前此类物证检验中存在的问题,提出今后工作的建议。

Metal solid substances and the like will melt into liquid state at the temperature greater than their respective melting point.The surface tension can render the melting tiny materials to form spherical or quasi-sphere particles when they are cooling,and even resulting in molten marks/patterns left on the surface of bigger metal object.Usually,local or partial high temperature will occur in the event of explosion,arson,electric shock or gun shooting.Therefore,forensic examination of the metal objects formed from melting to cooling and/or the molten marks/patterns is of great signifi cance to investigate the involving cases.Additionally,the melting-to-cooling-generated metal particles may give clues for speculating the suspects’job,e.g.,welding or cutting.Presently,forensic physicochemical examination pays more attention to chemical composition analysis,yet less or completely regardless to morphological examination.In this paper,through summarizing the examination methods about GSR,metal particles on electric marks,dross from welding and/or abrasive disc,the analysis was carried out into the micro-morphological characteristics and their formation mechanism at high temperature that had made the herementioned particles being produced,with discussions of their respective evidential value targeted.At last,suggestions were put forward to address subsistent problems about examining the evidence of the kind.