Pesquisa de técnica de revelação de adulteração de numeração estampada com carga hidráulica em chassis de veículos

Abstract

Automotive vehicles are highly valuable assets, and for this reason, they are often targets of theft and robbery. To allow their traceability and location, they have a unique serial number engraved on their chassis, called the Vehicle Identification Number (VIN). In the "car cloning crime", this number is erased and a new number is engraved in place of the previous one. To identify the original serial number, forensic scientists use special chemical reagents, where the reagent is applied to the surface of the chassis. These reagents can identify the erased serial number, as they react more strongly with the steel region below the erased number marks. The FRY reagent is the most commonly applied for this procedure, but the results are usually unsatisfactory and need to be improved. In this work, two modifications to the FRY reagent were tested to improve its performance: replacing copper chloride with iron chloride and anhydrous barium chloride. To increase the safety of the police officer during forensic activity, this work also proposed the creation of a chemical FRY reagent in paste form. The FRY paste reagent will reduce the risk of accidents during transportation and use in situations where forensic procedures have to be performed in the field. 2 mm thick SAE 1010 steel sheets were engraved with the number 3 using a punch and a universal hydraulic testing machine. To simulate tampering, the sample was sanded until the marking was completely removed. The development test was performed with three reagents: FRY (copper chloride, hydrochloric acid and distilled water); FRY mod1 (iron chloride, hydrochloric acid and distilled water); FRY mod2 (anhydrous barium chloride, hydrochloric acid and distilled water). The FRY reagent made the number 3 visible again after 34 seconds of application. However, the tested variations, mod1 and mod2, failed to reveal the erased marking even after 15 minutes of application. The FRY paste was made using the FRY reagent and alumina particles. It was possible to create an efficient paste that revealed the erased marking in a time interval of 1 minute and 40 seconds. It was possible to identify that copper chloride played a fundamental role in identifying the hardening zone. The use of chemical paste reagents for field forensic activities shows promise, maintaining the efficiency of the reagent and reducing the dangerousness of the activity.