Purpose: This paper aims to provide a review on the process of additive manufacturing of ceramic materials, focusing on partial and full melting of ceramic powder by a high-energy laser beam without the use of binders.Design/methodology/approach: Selective laser sintering or melting (SLS/SLM) techniques are first introduced, followed by analysis of results from silica (SiO₂), zirconia (ZrO₂) and ceramic-reinforced metal matrix composites processed by direct laser sintering and melting.Findings: At the current state of technology, it is still a challenge to fabricate dense ceramic components directly using SLS/SLM. Critical challenges encountered during direct laser melting of ceramic will be discussed, including deposition of ceramic powder layer, interaction between laser and powder particles, dynamic melting and consolidation mechanism of the process and the presence of residual stresses in ceramics processed via SLS/SLM.Originality/value: Despite the challenges, SLS/SLM still has the potential in fabrication of ceramics. Additional research is needed to understand and establish the optimal interaction between the laser beam and ceramic powder bed for full density part fabrication. Looking into the future, other melting-based techniques for ceramic and composites are presented, along with their potential applications.

Purpose: Polymeric parts produced by 3D stereolithography (SL) process have poorer mechanical properties as compared to their counterparts fabricated via conventional methods, such as injection or compression molding. Adding nanofillers in the photopolymer resin for SL could help improve mechanical properties. This study aims to achieve enhancement in mechanical properties of parts fabricated by SL, for functional applications, by using well-dispersed nanofillers in the photopolymers, together with suitable post-processing. Design/methodology/approach: Carbon nanotubes (CNTs) have high strength and Young’s modulus, making them attractive nanofillers. However, dispersion of CNTs in photopolymer is a critical challenge, as they tend to agglomerate easily. Achieving good dispersion is crucial to improve the mechanical properties; thus, suitable dispersion mechanisms and processes are examined. Solvent exchange process was found to improve the dispersion of multiwalled carbon nanotubes in the photopolymer. The UV-absorbing nature of CNTs was also discovered to affect the curing properties. With suitable post processing, coupled with thermal curing, the mechanical properties of SL parts made from CNTs-filled resin improved significantly. Findings: With the addition of 0.25 wt.% CNTs into the photopolymer, tensile stress and elongation of the 3D printed parts increased by 70 and 46 per cent, respectively. With the significant improvement, the achieved tensile strength is comparable to parts manufactured by conventional methods. Practical implications: This allows functional parts to be manufactured using SL. Originality/value: In this paper, an improved procedure to incorporate CNTs into the photopolymer was developed. Furthermore, because of strong UV-absorption nature of CNTs, curing properties of photopolymer and SL parts with and without CNT fillers were studied. Optimized curing parameters were determined and additional post-processing step for thermal curing was discovered as an essential step in order to further enhance the mechanical properties of SL composite parts.

This work presents a microporous silver cathode membrane reinforced with infiltration of samarium-doped ceria (SDC). The ion-conducting SDC effectively confines the surface of a porous silver membrane to maintain microporous structure and prevents the electrode agglomeration. SDC precursor solution is fired together with silver membrane at 700 °C for 2 h and formed as a nanocrystalline SDC on the silver pore surface. The SDC-infiltrated microporous silver membrane shows superior resistance to agglomeration without noticeable change in microstructures even at 900 °C for 12 h, which makes it promising for the application of solid oxide fuel cells as a cathode support.

Agglomeration of the nanoporous silver cathode decreases the performance of low temperature solid oxide fuel cells (LT-SOFCs). This work presents an inkjet-printed nanocomposite cathode using silver (Ag) and samarium-doped ceria (SDC) nanoparticles for better thermal stability. The fuel cell using Ag-SDC nanocomposite cathode showed 10 times lower degradation of output current density as compared to the cell using bare Ag cathode at 450 °C after 25 hours operation. The performance of Ag-SDC nanocomposite cathode also showed significant enhancement over bare Ag cathode.