Laser Assisted Foaming of Aluminum

Abstract

Aluminum is one of the most commonly used metals in some industries. In the automobile industries, it has gained acceptance owing to its recyclability, good corrosion resistance, low weight, and the energy saving benefits. Recently aluminum foams [1±12] have evoked considerable interest as an alternative material owing to their wide range of applications ranging from microelectronics, through automobiles to aerospace industries. The manufacturing techniques and characterization methods for aluminum foams require further development to acheive effective and economical use of this material. Various methods, [1±4] including casting and powder metallurgy, have been used with conventional melting and molding to produce Al-foams. In this communication an alternative process using a laser as the heat source will be described. This has the inherent advantage of unidirectional and localized foaming. The process is also fast, owing to rapid solidification, and the stabilization of pore formation can be controlled by coaxial gas flow and the laser processing parameters. In this communication we demonstrate the feasibility of unidirectional and localized expansion of the aluminum foam using the Nd-YAG/CO 2 laser and powder metallurgy. Fundamental aspects of the interaction of the laser beam with the foamable precursor material were investigated. We also examined the influence of the processing conditions on the evolution of cell morphology, and results concerning the density gradient were interpreted. This combined approach allows us to study the physical aspects of laser assisted foaming with respect to its production and quality.The experiments were performed with a 5 kW continuous wave (CW) CO 2 laser featuring a beam-bending optic, which consists of a metallic reflector set at 45 to the beam axis, directing the beam to an off-axis parabolic mirror (Fig. 1A). As specified for this system, it produces a multimode Gaussian beam with a maximum beam diameter of 40 mm. However, because of the anisotropic characteristic of the laser medium, especially the unavoidable diffraction effects, the beam shape is quasi-elliptical. So this beam is focused further by a 254 mm focal length off-axis parabolic mirror onto the target surface. The working distance was varied to produce a defocused spot size of 2±10 mm. An argon gas jet, with a flow rate of 20±40 L/min and coaxial to the beam axis, was used to COMMUNICATIONS 702 ADVANCED ENGINEERING MATERIALS 2001, 3, No. 9 ± [*] Dr.

Locally Controllable Surface Foaming of Polymers Induced by Graphene via Near-Infrared Pulsed Laser

“…It is challenging for conventional foaming technology to realize the locally controllable foaming of materials. Fortunately, the local foaming of materials can be achieved by using the laser, which has recently attracted increasing scholarly attention in particular for constructing porous structures and preparing the submicron foam. − …”

“…To date, several researches about laser foaming (as a new family of laser processing) mainly focused on the field of metals and biomacromolecules. For example, Kathuria used the Nd-YAG/CO 2 laser as the heat source to assist the foaming of aluminum . Gaspard and co-workers successfully prepared the microfoaming structure of gelatin films through single-pulse laser irradiation .…”

“…For example, Kathuria used the Nd-YAG/CO 2 laser as the heat source to assist the foaming of aluminum. 19 Gaspard and co-workers successfully prepared the microfoaming structure of gelatin films through single-pulse laser irradiation. 14 Generally speaking, laser irradiation can evoke a rapidly photothermal effect or reaction and generate an instantaneous high temperature, thereby resulting in the ablation, carbonization, and gasification or pyrolysis of materials.…”