Ref.: MmeEte34-002
Apresentador: Henrique Spohr
Autores (Instituição): Spohr, H.(Laboratório de Tubos de Calor); Caldas, L.d.(Laboratório de Tubos de Calor); Aguilar, V.C.(Laboratório de Tubos de Calor); Amaral, M.C.(Laboratório de Tubos de Calor); Martins, B.M.(Laboratório de Tubos de Calor); Krambeck, L.(Laboratório de Tubos de Calor); Xavier, F.A.(Universidade Federal de Santa Catarina); Mantelli, M.B.(Laboratório de Tubos de Calor);
Resumo:
Heat pipes are heat transfer devices used mainly as an effective way to transfer heat and achieve temperature homogenization. They use two-phase cycles of fluids as the principle of operation. These devices have several uses, from large offshore platforms to small electronic devices such as smartphones and tablets. Therefore, heat pipes can have many sizes, geometries and configurations depending on their application.
This work emphasizes on the manufacturing of flat loop heat pipes, widely applied on electronics and aerospace applications, which are commonly made of copper, a material that suits the solicitations involved and that can be readily diffusion bonded. In that sense, aluminum arises as an opportunity to reduce weight in flat loop heat pipes, presenting a density of 2.7 g/cm³ compared to the coppers 8,96 g/cm³. Aluminum also exhibits a higher corrosion resistance which can increase the heat pipes lifecycle.
Diffusion bonding is the main process used in the manufacturing of these devices. In this process, two or more contacting surfaces are welded in solid-state, applying an adequate combination of temperature, pressure and time, producing sound joints while avoiding undesirable flatness deformation. This study investigated the impact of process parameters as well as different interlayers on the diffusion bonding of AA 1100 applied for heat pipe manufacturing. The temperatures of 500 and 550ºC were evaluated, during 60 minutes. Copper was selected as the interlayer material, added in form of power, screen mesh and sheets of 0,1 and 0,3 mm thickness. The bond quality was qualitatively evaluated through microstructural characterization in optical microscope (OM) and scanning electron microscope (SEM), and quantitatively via shear strength. Additionally, composition analysis (EDS) was carried out to help understand the copper diffusion throughout the bond line and base material.