11 - Laser sintering of silicon powder and carbon nanofibers

Abstract

In the previous chapters, we have seen that laser processing can be employed, as an alternative method not only for machining but also for surface property modification. In this chapter an example where laser is used for sintering of powder-based materials will be detailed. Laser sintering is the method by which powdered materials are bonded by laser heating to produce solid, three-dimensional parts. It is an effective method to fabricate thick films. It is often applied to powders for the rapid fabrication of complex-shaped tools, molds, and prototypes. The technology can be applied to a wide range of materials: engineering plastics, thermoplastic elastomers, metals, and ceramics. Care must be taken in the sintering of ceramics; however, as sintering without a binder element is difficult. Sintering of a pure ceramic powder produces parts that are very fragile and prone to breakage. An appropriate binder element needs to be present in the heated powder during the sintering process. An additional material needs not necessarily be added to the powder; for example, in the sintering of silicon carbide, partial decomposition of silicon carbide produces silicon, which oxidizes to form silicon dioxide and can act as a binder element.