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.

troversially that some processes may be materials speci c. It seems that the taxonomy of manufacturing Solid freeforming is a genus of manufacturing processes is not well organised from the student's processes in which three-dimensional objects are assembled by point, line or planar addition of point of view and awaits completion. In the casting material. Confining surfaces, such as mould or die category, which embraces sand casting, die casting, walls, are absent. The shape is built by adding injection moulding, solvent casting, slip casting and rather than subtracting material. Solid freeforming microcasting methods such as LIGA (Lithogra ehas come to be computer controlled over the past Galvanoformung-Abformung), a change of state two decades in parallel with the expansion of the occurs against con ning surfaces that de ne the shape. data handling capacity of personal computers. It The range of state change methods includes phase can be used for rapid prototyping but also offers change, solvent evaporation, chemical reaction and mass production pathways in which individuation phase separation. In deformation methods, dies, rolls is possible. It is of particular interest for the and formers are used for compaction, drawing, creation, inter alia, of prosthetics that can be individually built from modified X-ray computed forging, rolling and spinning. Most of these processes tomographic data. Some routes offer the are now enhanced by computer control. Machining additional capability to control, from the computer, operations include carving, turning, milling, electronot just the shape but also the composition discharge machining, laser machining and etching, throughout a component. Thus, three-dimensional while joining methods such as welding, soldering, functional gradients in multiphase ordered brazing, adhesive bonding and the use of fasteners composites become possible. The concept of allow prefabricated components to be assembled to 'design' now embraces the integration of the achieve a higher level of complexity. spatial variation of composition, microstructure Some processes are missing from this list. The and hence of properties together with the shape creation of a coiled pot from clay can be dated to the parameters for multifunctional materials. This is a vast and expanding field in which the first 5th millennium BC.7 It does not t these categories textbooks are emerging. A review of this type must but is the historical antecedent of a solid freeforming necessarily be focused. The emphasis here process known as 'fused deposition modelling' (q.v.) therefore is placed on ceramic processing. This in which the computer controlled travel of an extruder review attempts to set out the taxonomy of solid nozzle builds a shape from linear extrudate.8 It is also freeforming in an historical context, disentangling not quite so easy to classify brickwork. Houses are the multiplicity of process names that have arisen not made by building a large block of masonry and over the past two decades. Special emphasis is machi...

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A single-step fabrication of ZnSb nanostructures using template-free electrochemical deposition was developed. Results have indicated that ZnSb nanoflakes, nanowires, or nanoparticles with controlled composition could be obtained by adjusting the precursor concentration, applied voltage, and substrate type. The ZnSb nanostructures deposited on Cu foils were directly used as Li-ion battery anodes without the addition of any binder. Electrochemical analyses revealed that the interconnected ZnSb nanoflakes depicted high discharge capacities and a stable performance, which were better than that of ZnSb nanowires and nanoparticles. With an initial discharge capacity of 735 mA h/g and an initial Columbic efficiency of 85%, the ZnSb nanoflakes maintained a discharge capacity of 500 mA h/g with a Coulombic efficiency of 98% after 70 cycles at a current density of 100 mA/g (0.18 C). The ZnSb nanowires and nanoparticles showed a capacity of 190 and 40 mA h/g, respectively, after 70 cycles at the same current density. The improved performance of the interconnected ZnSb nanoflakes is attributed to their open structure, with a large surface area and small crystal grains, to facilitate the diffusion of Li ions and to buffer the large volume swings during the lithium intercalation process.

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The long-term success of a biomaterial used during surgery may be compromised by infection. A possible effective solution is to make the biomaterial osteoconductive and antibacterial. A range of silver-substituted hydroxyapatite (AgHA) of up to 1.1 wt. % of Ag was synthesized. AgHA displayed a rod-like morphology of dimensions ~50 nm in length and ~15 nm in width. Phase-pure AgHA was demonstrated in the X-ray diffraction patterns and Fourier transform infrared spectroscopy spectra. Comparing with hydroxyaptite (HA), 0.5AgHA exhibited a 3-log reduction in the number of bacteria. Diffusion of the entrapped Ag(+) ions towards the crystal structure surface was revealed by an increase of 6 at. % Ag in the X-ray photoelectron spectroscopy results. Furthermore, less than 0.5 ppm of Ag(+) ions being released from 0.5AgHA into the deionized water medium was evidenced from the inductively coupled plasma mass spectrometry results. AgHA produced by co-precipitation gave rise to minimal release of Ag(+) ions. It was hypothesized that the diffused surface Ag(+) ions damaged the bacteria cell membrane and impede its replication. With the culturing time, significant increase in the number of human mesenchymal stem cells (p < 0.05) was demonstrated on 0.5AgHA.

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