Fabricação e caracterização de uma estrutura capilar por sinterização de pó de cobre para aplicação em tubos de calor

Abstract

In this work, the preparation of porous structures from copper metal powder by the sintering process was discussed and studied, in order to predict its applicability as a capillary structure in heat pipes. This structure is responsible for the capillary pumping of the working fluid inside the passive heat transfer devices. This experimental study comprised the analysis of the raw material, the process of obtaining the porous structure, the preparation of experimental benches and the results of their respective tests (permeability, porosity, critical radius and thermal conductivity). Copper powder was analyzed using Shimadzu ™ EDX-7000 Energy Dispersion X-Ray Fluorescence Spectrometry (ED-XRF), by Laser Diffraction Granulometry on a Cilas™ Granulometer and by Scanning Electron Microscopy in a VEGA3 Tescan™. The capillary structure was sintered in an Inti ™ FT-1200 horizontal tubular oven with a controlled atmosphere composed of 95% Argon and 5% Hydrogen. The porosity of the sintered structure was evaluated by the Archimedes Method, based on the MPIF Standard 42 (Denomination of density of Compactor Sintered Powder Metallic Products), and the Helium Pycnometry. An experimental bench was developed to survey the properties of permeability and critical radius, based on the MPIF Standard 39 (Determination of Properties of Sintered Bronze P / M Filter Powders), and an experimental bench for thermal conductivity evaluation, based on NBR 15220 Part 04 (Desempenho térmico de edificações - Parte 4: Medição da resistência térmica e da condutividade térmica pelo princípio da placa quente protegida). Thermal experimental tests of the sintered heat pipes showed that the capillary structure worked satisfactorily, making possible the use of sintered powder as a capillary structure for Heat Pipes.