Biomedical Engineering Reference
In-Depth Information
Figure 31.14.
Schematic layout of the SLS process.
46
powders and must be extracted from the powder bed after fabri-
cation (Fig. 31.14). Because the powders are subjected to low com-
pactionforcesduringtheirdepositiontoformnewlayers,fabricated
structures are usually porous.
SLS is an effective method for creating complex-shaped proto-
types and allows for the design of anatomically shaped scaffolds
with defined pore sizes, porosity, and topographies. In fact, SLS-
fabricated scaffolds possess the best mechanical properties among
all SFF technologies, and it is the preferred fabrication process for
producing complex porous ceramic matrices suitable for implanta-
tion in bone defects. Various materials, including polymers, ceram-
ics, metallic powder, and their composites, can be processed using
the SLS system. However, because the SLS technology involves high
processingtemperatures,thetechnologyislimitedtotheprocessing
ofthermallystablepolymers.
44
-
46
Further,theporescreatedinSLS-
fabricatedscaffoldsaredependentontheparticlesizeofthepowder
stock used; typical pore sizes encountered in SLS-fabricated struc-
tures are limited to smaller pore sizeranges (
<
50
μ
m).
Lee
et al
. first fabricated ceramic bone implants using SLS tech-
nology and CP powders of various Ca/P ratios in 1993.
47
The pow-
derswerecoatedwithanintermediatepolymerbinder,poly(methyl
methacrylate-co-n-butyl methacrylate) emulsion copolymer,
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