Influence of foaming agents on laser based manufacturing of closed-cell Ti foam

Abstract

Titanium offers a high specific strength, low density, and excellent corrosion resistance. It finds application in many fields like automotive, aerospace, drilling, and biomedical industries. To improve the adherence of bone cells on implants a rough surface can be of advantage. Such a surface is featured by a foamed stru cture. For achieving a foamed Ti structure, laser induced foami ng was used. In this case, Ti powder is pre mixed with foaming agents. The foaming agents are degraded by laser induced energy and produce gaseous products like carbon dioxide, while the Ti powder is molten by the laser. Due to the fast cooling rate carb on dioxide forms gaseous bubbles in the solidifying material. Mandatory for the foaming agents is that they are biocompatible. Previous studies using the foaming agents CaCO 3 , MgCO 3 , MgTiO 3 , and MgTiO 3 mixed to Ti powder resulted in a porosity of up to 0.3. By varying the content of the foaming agent por osity and pore diameter of the samples were adjusted. It is expected that an increased porosity could be achieved by mixing the foaming agents among each other. The influence of the specific foaming agents and their mixtures on the porosity is pres ented in this work. By mixing the foaming agents together and adding them to the powder, the porosity of the samples was increased compared to only adding one foaming agent to the powder.