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The consolidation process and morphology evolution in ceramics-based additive manufacturing (AM) are still not well-understood. As a way to better understand the ceramic selective laser sintering (SLS), a dynamic three-dimensional computational model was developed to forecast thermal behavior of hydroxyapatite (HA) bioceramic.

AM has revolutionized automotive, biomedical and aerospace industries, among many others. AM provides design and geometric freedom, rapid product customization and manufacturing flexibility through its layer-by-layer technique. However, a very limited number of materials are printable because of rapid melting and solidification hysteresis. Melting-solidification dynamics in powder bed fusion are usually correlated with welding, often ignoring the intrinsic properties of the laser irradiation; unsurprisingly, the printable materials are mostly the well-known weldable materials.

The consolidation mechanism of HA was identified during its processing in a ceramic SLS device, then the effect of the laser energy density was studied to see how it affects the processing window. Premature sintering and sintering regimes were revealed and elaborated in detail. The full consolidation beyond sintering was also revealed along with its interaction to baseplate.

These findings provide important insight into the consolidation mechanism of HA ceramics, which will be the cornerstone for extending the range of materials in laser powder bed fusion of ceramics.

Three-dimensional (3D) printing technology allows geometric complexity and customization with a significant reduction in the structural environmental impact. Nevertheless, it poses a serious threat to the environment when organic binders are used. Binder jet printing of alkali-activated geopolymer precursor can represent a successful and environmental-friendly alternative.

The present work reports about the successful 3D printing of metakaolin-based alkali-activated concrete, with dimensional integrity and valuable mechanical behavior.

The geometric behavior was studied as a function of alkali activator flow rate, and the minimum geometric deviation with complete saturation was recorded at 103 mg/s. The printed specimen is characterized by a modulus of rupture as high as 4.4 MPa at 135 mg/s.

The 3D printed geopolymer-based concrete can be potentially used in a wide range of structural applications from construction to thermal insulation elements.

The analysis of the 3D geopolymer-based concrete printing system and material conducted in this paper is original.

Recent advances in 3D printing construction elements have focused on ordinary Portland cement (OPC) concrete using polymeric binders; herein, this study aims to produce the same using pure water.

A binder jet printer prototype was used to fabricate specimens that are used to assess geometric and mechanical properties. Two distinct water-based binder formulations, compatible with OPC chemistry and piezoelectric jetting device, were used: pure water and water-polyvinyl alcohol (98:2 w/w) solution.

This study examines the effect of binder flow rate on dimensional accuracy. Furthermore, the changes in the mechanical properties over time with hydration have been investigated.

Results indicate that the increase in mechanical strength of Portland cement concrete with pure water was consistent; however, it was delayed by the water: PVA (98:2 w/w) solution. Post-curing by water vapor hardened the structure with the removal of layering native to 3DP and decreased infilling porosity by diffusion mechanism.

This paper has used pure water jetting for BJT of Portland cement-containing bodies.

For metal additive manufacturing, metallic powders are usually produced by vacuum induction gas atomization (VIGA) through the breakup of liquid metal into tiny droplets by gas jets. VIGA is considered a cost-effective technique to prepare feedstock. In VIGA, the quality and the morphology of the produced particles are mainly controlled by the gas pressure used during powder production, keeping the setup configuration constant.

In VIGA process for metallic additive manufacturing feedstock preparation, the quality and morphology of the powder particles are mainly controlled by the gas pressure used during powder production.

In this study, Inconel-625 feedstock was produced using a supersonic nozzle in a close-coupled gas atomization apparatus. Powder size distribution (PSD) was studied by varying the gas pressure.

The nonmonotonic but deterministic relationships were observed between gas pressure and PSD. It was found that the maximum 15–45 µm percentage PSD, equivalent to 84%, was achieved at 29 bar Argon gas pressure, which is suitable for the LPBF process. Following on, the produced powder particles were used to print tensile test specimens via LPBF along XY- and ZX-orientations by using laser power = 475 W, laser scanning speed = 800 mm/s, powder layer thickness = 50 µm and hatch distance = 100 µm. The yield and tensile strengths were 9.45% and 13% higher than the ZX direction, while the samples printed in ZX direction resulted in 26.79% more elongation compared to XY-orientation.

The purpose of this paper is to eliminate Part defects and enrich additive manufacturing of ceramics. Laser powder bed fusion (L-PBF) experiments were carried to investigate the effects of laser parameters and selective oxidation of Titanium (mixed with TiO₂) on the microstructure, surface quality and melting state of Titania. The causes of several L-PBF parts defects were thoroughly analyzed.

Laser power and scanning speed were varied within a specific range (50–125 W and 170–200 mm/s, respectively). Furthermore, varying loads of Ti (1%, 3%, 5% and 15%) were mixed with TiO₂, which was selectively oxidized with laser beam in the presence of oxygen environment.

Part defects such as cracks, pores and uneven grains growth were widely reduced in TiO₂ L-PBF specimens. Increasing the laser power and decreasing the scanning speed shown significant improvements in the surface morphology of TiO₂ ceramics. The amount of Ti material was fully melted and simultaneously changed into TiO₂ by the application of the laser beam. The selective oxidation of Ti material also improved the melting condition, microstructure and surface quality of the specimens.

TiO₂ ceramic specimens were produced through L-PBF process. Increasing the laser power and decreasing the scanning speed is an effective way to sufficiently melt the powders and reduce parts defects. Selective oxidation of Ti by a high power laser beam approach was used to improve the manufacturability of TiO₂ specimens.

This paper aims to reduce part defects and improve ceramic additive manufacturing (AM). Selective laser melting (SLM) experiments were carried out to explore the effect of laser power and scanning speed on the microstructure, melting behaviour and surface roughness of cuprous oxide (Cu₂O) ceramic.

The experiments were designed based on varying laser power and scanning speed. The laser power was changed between 50 W and 140 W, and the scanning speed was changed between 170 mm/s and 210 mm/s. Other parameters, such as scanning strategy, layer thickness and hatch spacing, remain constant.

Laser power and scan speed are the two important laser parameters of great significance in the SLM technique that directly affect the molten state of ceramic powders. The findings reveal that Cu₂O part defects are widely controlled by gradually increasing the laser power to 110 W and reducing the scanning speed to 170 mm/s. Furthermore, excessive laser power (>120 W) caused surface roughness, cavities and porous microstructure due to the extremely high energy input of the laser beam.

The SLM technique was used to produce Cu₂O ceramic specimens. SLM of oxide ceramic became feasible using a slurry-based approach. The causes of several part defects such as spattering effect, crack initiation and propagation, the formation of porous microstructure, surface roughness and asymmetrical grain growth during the SLM of cuprous oxide (Cu₂O) are thoroughly investigated.

This study aims to describe the effects of capillary forces or action, viscosity, gravity and inertia via the computational fluid dynamics (CFD) analysis. The study also includes distribution of the binder droplet over the powder bed after interacting from different heights.

Additive manufacturing (AM) has revolutionized many industries. Binder jetting (BJT) is a powder-based AM method that enables the production of complex components for a wide range of applications. The pre-densification interaction of binder and powder is vital among various parameters that can affect the BJT performance. In this study, BJT process is studied for the binder interaction with the powder bed of SS316L. The effect of the droplet-powder distance is thoroughly analysed. Two different droplet heights are considered, namely, h1 (zero) and h2 (9.89 mm).

The capillary and inertial effects are predominant, as the distance affects these parameters significantly. The binder spreading and penetration depth onto the powder bed is influenced directly by the distance of the binder droplet. The former increases with an increase in latter. The binder distribution over the powder bed, whether uniform or not, is studied by the stream traces. The penetration depth of the binder was also observed along the cross-section of the powder bed through the same.

In this work, the authors have developed a more accurate representative discrete element method of the powder bed and CFD analysis of binder droplet spreading and penetration inside the powder bed using Flow-3D. Moreover, the importance of the splashing due to the binder’s droplet height is observed. If splashing occurs, it will produce distortion in the powder, resulting in a void in the final part.

The study aims to examine the mediating role of psychological empowerment and job crafting between servant leadership and innovative work behavior.

The data were collected from 689 knowledge workers employed in Pakistan's service industry. The data collection was done through survey design. The data analysis was done through structural equation modeling using PLS-Smart.

Servant leadership was found to be related to psychological empowerment, job crafting and innovative work behavior of the employees. Job crafting was found to be mediating between servant leadership and innovative work behavior. Additionally, psychological empowerment and job crafting were found to be sequential mediators between servant leadership and innovative work behavior.

The study delineated the link mechanism between servant leadership and innovative work behavior.

The purpose of this study was to use bridge curvature method (BCM) to quantify stress, while multiscale modeling with adaptive coarsening predicted distortions based on experimentally validated models. Taguchi method and response surface method were used to optimize process parameters (energy density, hatch spacing, scanning speed and beam diameter).

Laser powder bed fusion (LPBF) offers significant design freedom but suffers from residual stresses due to rapid melting and solidification. This study presents a novel approach combining multiscale modeling and statistical optimization to minimize residual stress in SS316L.

Optimal parameters were identified through simulations and validated with experiments, achieving an 8% deviation. This approach significantly reduced printing costs compared to traditional trial-and-error methods. The analysis revealed a non-monotonic relationship between residual stress and energy density, with an initial increase followed by a decrease with increasing hatch spacing and scanning speed (both contributing to lower energy density). Additionally, beam diameter had a minimal impact compared to other energy density parameters.

This work offers a unique framework for optimizing LPBF processes by combining multiscale modeling with statistical techniques. The identified optimal parameters and insights into the individual and combined effects of energy density parameters provide valuable guidance for mitigating residual stress in SS316L, leading to improved part quality and performance.

The purpose of the study is to ascertain the mediating role of meaning between servant leadership and work engagement. The study also explores the relationship between servant leadership and work engagement.

The data were collected from 704 service sector employees working in Pakistan through survey design. The data analysis was done through structural equation modeling using PLS-Smart and hierarchical regression using SPSS.

The results revealed that servant leadership was related to meaning and work engagement. Moreover, meaning was found to be related to work engagement. Finally, meaning was found to mediate the relationship between servant leadership and work engagement.

The research has ascertained the previously unexplored mediating role of meaning between servant leadership and work engagement.