ANÁLISE NUMÉRICA DAS PROPRIEDADES TÉRMICAS NO PROCESSO DE REMOÇÃO DO METAL EM CALCÁRIO POR ABLAÇÃO TÉRMICA

Abstract

. The thermal ablation process is an advanced manufacturing technology that has drawn the attention of modern industry to its ability to perform microprocessing and nanomanufacturing. The fields of medicine, aerospace engineering, polymer manufacturing and welding are some of the main ones that utilize the method. Assuming that when solid parts are sufficiently heated, some materials can undergo a phase transition, changing from solid to gaseous state, this process being called "sublimation". If the material is heated quickly enough, in an environment with controlled boundary conditions, material is removed by sublimation, a process known as "thermal ablation". This phenomenon occurs when focusing a laser on a prototype, in a controlled environment. If the material reaches the sublimation temperature, ablation occurs on a scale proportional to the sublimation factor. In this way, a portion of the material transforms to the vapor state instantly, as a result of the rapid temperature variation, removing mass from the prototype system. This study presents a transient numerical analysis of the thermal behavior of materials during the ablation phenomenon through laser heating. The present work was done by replicating parts of a previously published experiment on the removal of an ore layer in a limestone monument by ablation. It also contains information about the software modeling of the described situation (with the basic programming of the process in the software COMSOL) and the effects/interaction of the laser pulse on the materials. The energy efficiency of the ablation process was calculated, comparing the use of a moderate and stable laser flux to a high peak energy laser pulse in terms of preserving the lower layers of the material. From the analysis of the temperature distribution obtained in the study of the problem of laser heating in thermal ablation and the parameters that influence the process, it was proved that shorter pulses with higher laser intensity have better energy efficiency compared to a long and stable flow.