Citation: Ur Rehman, A.; Saleem,
M.A.; Liu, T.; Zhang, K.; Pitir, F.;
Salamci, M.U. Influence of Silicon
Carbide on Direct Powder Bed
Selective Laser Process
(Sintering/Melting) of Alumina.
Materials 2022, 15, 637. https://
doi.org/10.3390/ma15020637
Academic Editors: Ludwig Cardon
and Clemens Holzer
Received: 1 November 2021
Accepted: 14 December 2021
Published: 15 January 2022
Publisher’s Note: MDPI stays neutral
with regard to jurisdictional claims in
published maps and institutional affil-
iations.
Copyright: © 2022 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
Article
Influence of Silicon Carbide on Direct Powder Bed Selective
Laser Process (Sintering/Melting) of Alumina
Asif Ur Rehman
1,2,3,
* , Muhammad Ahsan Saleem
4
, Tingting Liu
4,
*, Kai Zhang
4
, Fatih Pitir
1
and Metin Uymaz Salamci
2,3,5
1
ERMAKSAN, Bursa 16065, Turkey; Fatih.pitir@ermaksan.com.tr
2
Department of Mechanical Engineering, Gazi University, Ankara 06570, Turkey; msalamci@gazi.edu.tr
3
Additive Manufacturing Technologies Research and Application Center-EKTAM, Gazi University,
Ankara 06560, Turkey
4
School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China;
ahsansaleem@njust.edu.cn (M.A.S.); Zhangkai@njust.edu.cn (K.Z.)
5
Manufacturing Technologies Center of Excellence-URTEMM A.S., Ankara 06560, Turkey
* Correspondence: asyf.rehman@gmail.com (A.U.R.); Liutingting@njust.edu.cn (T.L.);
Tel.: +90-539-938-780-01 (A.U.R.); +86-138-130-848-95 (T.L.)
Abstract:
The powder bed selective laser process (sintering/melting) has revolutionised many
industries, including aerospace and biomedicine. However, PBSLP of ceramic remains a formidable
challenge. Here, we present a unique slurry-based approach for fabricating high-strength ceramic
components instead of traditional PBSLP. A special PBSLP platform capable of 1000
◦
C pre-heating
was designed for this purpose. In this paper, PBSLP of Al
2
O
3
was accomplished at different SiC
loads up to 20 wt%. Several specimens on different laser powers (120 W to 225 W) were printed.
When the SiC content was 10 wt% or more, the chemical interaction made it difficult to process.
Severe melt pool disturbances led to poor sintering and melting. The structural analysis revealed that
the micro-structure was significantly affected by the weight fraction of SiC. Interestingly, when the
content was less than 2 wt%, it showed significant improvement in the microstructure during PBSLP
and no effects of LPS or chemical interaction. Particularly, a crack pinning effect could be clearly seen
at 0.5 wt%.
Keywords:
additive manufacturing; 3D printing; selective laser sintering/melting (PBSLP);
ceramic
;
composites
1. Introduction
Additive manufacturing (AM) has revolutionised many industries, and more are
diving in, partially or completely, to accomplish design freedom with reduced time to
market [
1
–
9
]. LPBF is AM method for producing parts and freeform articles in such a
way that the manufacturing layer is fused selectively by a high-energy laser beam [
10
]
after powder deposition [
11
–
14
]. LPBF is able to achieve 100 percent density and excellent
mechanical properties [
15
–
20
] for alloys with melting of powder particles. It is of great
interest to accomplish direct LPBF for non-weldable materials including ceramics [
21
,
22
]
due to its utility in many applications. Indirect LPBF of ceramics is achievable using metal,
polymer or glass as binder to consolidate parts. These binders can also be removed by
debinding in the case of polymers [
23
]. However, due to the low densities and weak binding
strength, the horizon of application is very limited. Direct LPBF can give
100 percent
density
of ceramics; however, melting–solidification dynamics increase thermal stresses, which
make it impossible to obtain consistent ceramic parts. By controlling the laser melt pool
and reducing thermal stresses, ceramics parts production could be possible, but clear
information on melt pool physics as well as laser–material interaction is needed.
LPBF has the extraordinary cycling rate of heating and cooling which triggers nonequi-
librium conditions; new microstructures and material phases are usually formed during
Materials 2022, 15, 637. https://doi.org/10.3390/ma15020637 https://www.mdpi.com/journal/materials
