Powder Bed Selective Laser Processing of Alumina: Scanning Strategies Investigation

Abstract

Powder Bed Selective Laser Processing (PBSLP) is a promising technique for the additive manufacturing of alumina. For the method’s success, PBSLP process parameters such as laser power, scanning speed, hatching distance, and scanning strategies need to be investigated. This paper focuses on studying the scanning strategies’ effects on the PBSLP of alumina numerically and experimentally. Scanning strategies such as linear with different orientation, concentric, and islands were investigated. A numerical model was developed in which the PBSLP parameters, scanning strategy effects, and interpreting the experimental results could be observed. The numerical model proved its ability to reach the proper process parameters instead of using experimental trails which are time and cost consuming. For relative density, the island strategy succeeded to print alumina samples with a high relative density reaching 87.8%. However, there are round passages formed inside the samples that remain a barrier for the island strategy to be effectively used in PBSLP of alumina. Both linear and concentric strategies achieved a relative density of 75% and 67%, respectively. Considering the top surface roughness, samples printed with linear strategies gave low top surface roughness compared to the island and concentric strategies. Linear-45° is considered the effective strategy among the studied strategies as it achieved good relative density and low roughness at top and side surfaces. For PBSLP of alumina, new scanning strategies should be considered, and this study presents a new scanning strategy that is mainly based on space filling mathematical curves and should be studied in future work.

Additive manufacturing of Al2O3 ceramics with MgO/SiC contents by laser powder bed fusion process

“…This is believed to be a severe issue for printing ceramics and composites due to their low thermal shock resistance (Zhang et al, 2022). Researchers have studied numerous individual aspects that affect the LPBF method, such as pre-heating, the surrounding temperature, scan speed, hatch distance, beam power, intervals duration, scanning strategy (orthogonal, islands, zigzag pattern, and many others), the effects of the non-steady-state melt regimes in the scanning tracks, the role of pores on crack initiation, laser pre-heating of ceramic material, powder particle density, and so on (Yamakov et al, 2002;Wilkes et al, 2013;Schwentenwein and Homa, 2015;Wang et al, 2017;Liu et al, 2020;Waqar et al, 2021b;Gokcekaya et al, 2021;Abdelmoula et al, 2022;Sun et al, 2022;Wang et al, 2022). Directly manufacturing highly dense ceramics with LPBF might result in fractures and other manufacturing flaws (Yamakov et al, 2002;WIPO, 2018).…”

Multi-Layer Simulation of the Powder Bed Selective Laser Processing of Alumina for Residual Stress and Distortion Evaluation

“…The alumina samples were printed and used for the model validation. Based on our previous study [ 29 ], it was recommended to use a low scanning speed with alumina to minimize the laser beam inertia effect on the powder particles. Therefore, a scanning speed of 200 mm/s was considered.…”

“…Nowadays, the AM of ceramics is undergoing rapid developments, whether in terms of feedstock or the application of AM techniques. Many studies have been conducted on the AM of ceramic materials using various techniques such as binder jetting, extrusion, and PBSLP [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ]. Among the techniques used, PBSLP is regarded as the most suitable for ceramic materials because it can produce a dense structure with more accurate shape dimensions and without the need for initial powder or post-treatment operations to achieve the final shape [ 30 ].…”

“…According to the presented literature review, researchers have carried out numerous experimental trials and have spent considerable time determining the best process window for the PBSLP of studied ceramic materials. Furthermore, previous numerical studies on the PBSLP of ceramic materials have investigated either a single-track [ 27 , 28 , 29 , 42 , 43 , 44 , 45 ] or one-layer simulation [ 46 ]. Using numerical modeling to predict the process output is a powerful tool and should be considered in AM to obtain a general view about the effect of the process parameters [ 47 , 48 , 49 ].…”

“…Using numerical modeling to predict the process output is a powerful tool and should be considered in AM to obtain a general view about the effect of the process parameters [ 47 , 48 , 49 ]. Concerning the laser heat source, several previous studies [ 29 , 35 , 36 , 42 ] have focused on using either fiber or Nd-YAG lasers for the PBSLP of alumina, despite the fact that the CO 2 laser is considered to be the best choice based on its interaction with alumina.…”