Page 9 - MSAM-2-3

Materials Science in Additive Manufacturing High-performance materials in AM

A B C

Figure 2. Typical vital defects in real-time curing binder jetting additive manufacturing. (A) Real-time cured layers during printing (inside powder bed).
(B and C) Real-time cured layers and green parts after an ultraviolet irradiation (outside powder bed) .
[10]

structure. The molten material is released through the
nozzle and the direction of deposition is changed in the
process by adjusting the relative movement of the platform
or nozzle [15,16] . Figure 3 presents the working principle of a
general laser powder DED (LP-DED) system .
[17]
DED technology is well suited for the preparation of
high-performance metallic materials and is also suitable
for the processing of some ceramic materials . Compared
[18]
to other AM technology, DED technology offers a number
of advantages, including faster build rates, the capability
to produce large parts, the ability to fabricate under non- Figure 3. Demonstration of the working principle of a general laser
[17]
horizontal conditions, the ability to print in weightless powder directed energy deposition system .
environments under certain conditions, and the ability
to deposit multiple materials simultaneously on some (L-DED) have emerged. With the aid of in situ rolling, the
models [18,19] . This makes DED technology a promising product has a unique initial microstructure, which results
technology for a wide range of applications. in relatively low uniform elongation and relatively high
ultimate tensile stress .
[23]
The DED technology can also be used for the repair
and addition of materials onto existing components. 2.3. Material extrusion
With DED technology, it is possible to achieve higher MEX technology is a very established AM technique.
precision, lower residual stresses and a more flexible repair It builds 3D parts by heating a linear composite or
[20]
process than with conventional welding repair methods . thermoplastic material to soften it, followed by depositing
Research into DED technology is becoming increasingly and curing it layer by layer . In particular, while printing
[24]
advanced due to its outstanding advantages, with recent biomaterials by means of MEX, the material is extruded
studies showing, for example, that the final performance of from the nozzle and then forms the structure . The
[25]
products can vary considerably under different scanning process is shown in Figure 4.
strategies . Nonetheless, there are disadvantages of using MEX technology is well suited for use in domestic or
[21]
DED technology. In most cases, the components formed by non-professional applications, and it also has applications
DED technology have a relatively low resolution and often in the medical field due to its high degree of customizable
require post-processing to complete the final product. The flexibility . At present, this technology has proven to
[26]
anisotropy of the product itself is significant and requires be very compatible with more than 20 thermoplastics,
dynamic adjustment of parameters to reduce the impact such as acrylonitrile butadiene styrene (ABS), polyamide
of this on the performance of the fabricated product [20,22] . 66 (PA66), and aliphatic polyamides (PA, also known as
In response to the above problems, researchers have nylon). New research has shown that MEX technology
also attempted to solve them in recent years by improving is also suitable for polymers such as PEEK or ceramic
and perfecting the hardware of DED devices. Novel devices materials, which will be described in more detail in
such as rolling-assisted laser directed energy deposition subsequent sections of this paper .
[24]

Volume 2 Issue 3 (2023) 3 https://doi.org/10.36922/msam.1587