Two-dimensional hexagonal photonic crystals of air columns in a wax substrate were fabricated by jet-based methods. By modifying the structure of the photonic crystals (PC), electromagnetic waves can be controlled, enabling the design of novel devices for waveguides, filters, and couplers. The jet-based processing is a solid freeforming method that can fabricate complex 2D or 3D photonic structures quickly and easily as compared to micro-machining and lithographic methods. The resolution of our 3D Systems ThermoJet® solider object printer is 300 × 400 × 600 dpi (XYZ) with the layer thickness of 0.042 mm. The wax used is a thermopolymer build material, similar to production investment casting wax material. The periodicity of the lattice of our 2D PC structures was designed to form bandstop filters in the 0.1–0.3 THz range. Transmission spectra of the structures were measured with a Bruker IFS 66v FT-IR interferometer. Photonic band gaps were observed at 0.17 THz and 0.23 THz along the Γ-M direction for both the TM and TE polarized incident beam for the PC structures with lattice constant of 0.787 mm and 0.586 mm, respectively. The location and width of the bandgaps agree with theoretical calculation based on a block-iterative frequency-domain method for Maxwell's equations in a planewave basis. To the best of our knowledge, this is the first time a jet-based process has been used successfully to fabricate PC structures at these high frequencies. However, the ThermoJet® printer as well as other current available solid freeforming technologies lack the resolution to PC structures operating in the terahertz regime. To extend this technology to terahertz applications, such as terahertz lasers, waveguides, and imaging system, a 10-fold increase in machine resolution is required to produce finer structures. Engineering materials with lower electromagnetic absorption and higher dielectric constants at terahertz frequencies are also critical to developing THz photonic bandgap technology.

Rapid Prototyping and Tooling are playing a more and more important role in the achievement of compressed time-to-market solutions, where prototype parts and tools are produced directly from the CAD model. In particular, Selective Laser Sintering (SLS) of metal powders with liquid phase is frequently applied for the production of inserts for injection moulding of plastic parts.

An experimental campaign has been planned to investigate the surface finish and mechanical performances of Direct Laser Sintering technique, with particular regard to the effect of the laser sintering strategy on the anisotropy of the final part. Tensile specimens of DirectMetal 20 and DirectSteel 20 materials have been produced, with different orientations in regard to laser path.

Rupture surfaces after the tensile tests were observed at the SEM, in order to understand failure mechanisms, whereas the observation of polished sections helped investigating joining phenomena between the particles. The proposed experimental methodology allowed correlating the macroscopic performances to the micro-mechanisms ruling the process, proving that no considerable differences can be noticed between samples produced in the X and Y direction within the plane of powder deposition.

The development of ink synthesis for YBa2Cu3O7−δ (YBCO) coated conductors is discussed in detail. These chemical solution deposition (CSD) processes are for drop-on-demand ink-jet coating and ink-jet printing allowing non-vacuum formation of multi-layer superconducting patterns on metal substrates (with and without the aid of buffer layers).

Printing and substrate parameters that alter solid-liquid interface properties were investigated, and the sol-inks synthesised were aqueous and non-aqueous based therefore allowing variable chemical properties depending on what was required from the deposition process. The formation and the stability of the sol-inks has been studied and discussed, with the various synthesis steps and additives yielding the properties required to produce coatings.

Characterisation of the inks was by Differential Thermal Analysis and Thermal Gravimetry whilst characterisation of the coatings and products was by X-Ray Diffraction and Scanning Electron Microscopy. AC susceptibility was used to assess the superconductivity of the printed samples.

The development and status of a novel electrospray system, capable of a variety of applications, including the fabrication of tissue engineered structures is described. The system requirements dictate the following key components: a micro-fabricated silicon electrospray emitter, a mass spectrometer capable of selecting molecules having a charge to mass ratio up to 32, 000 with a resolution of 10, 000, and an integrated ion optics system permitting depositing the selected molecules ‘softly’ onto a target with a spatial resolution of 0.1μm. One critical feature of the system is the overall efficiency of transferring biomolecules from a buffer solution, typically comprising water, acetonitrile and ammonium acetate, into an ion flux. Commercial ES/MS systems are generally designed with simplicity of operation as a design driver, together with the low probability of transmitting spray droplets directly into the quadrupole mass selection system. This has focused attention onto the detailed design and characterization of the electrospray emitter and the environment into which the spray is launched. This has highlighted the need to evaluate in detail, an electrospray operating into a low pressure environment and to improve our understanding of the interaction between voltage and flow rate in the transition from nano-electrospray mode, wherein no positive pressure is applied to the fluid and normal electrospray mode, close to minimum flow rate. Early results of this investigation are presented. There is evidence that at reduced ambient pressure there is a small reduction in spray current, however this is offset by improved transmission of the beam into the first quadrupole stage.

The direct manufacture of metal parts by rapid prototyping often involves building a porous skeleton from a metal powder. In this work, a method termed Homogeneous Steel Infiltration has been developed for infiltrating steel skeletons to make conventional tool steel alloys. The method uses a gated infiltration route that uses as the infiltrant a steel alloy with a lower melting point than the base powder. The infiltrant liquid may use carbon and/or silicon as a melting point depressant. Premature freeze-off of the steel infiltrant is avoided by operating at a temperature where some liquid is stable at chemical equilibrium. The compositions of the skeleton and infiltrant and the infiltration temperature are selected by using computational thermodynamics. Examples of successful infiltrations using D2 and A3 tool steels as target compositions are shown. The thermodynamic design method enables suitable parameters to make other tool steels, some stainless steels and manganese steels.

The interaction of an inkjet printed droplet with a substrate is of importance when determining the final size and shape of deposits. A simple model is proposed that relates droplet diameter, printed dot pitch and equilibrium contact angle to as-printed track width. Reasonable agreement was found between the model and final track width, with slight over-prediction accounted for by removal of the organic component of the ink during heat treatment. Immediately after droplet impact, the drop may spread to a considerably greater extent than predicted by equilibrium because of the kinetic energy of the droplet in flight. Simulations of droplet impact showed that the maximum droplet spread decreased linearly with equilibrium contact angle. Recoil of these droplets towards their equilibrium shape occurred above a threshold contact angle. This threshold was greater than expected, suggesting an energy barrier preventing recoil or the kinetics of recoil being too slow for recoil to occur within the timeframe of this study.

We present a concept for multi-material solid freeform fabrication of 2D and layered 3D heterogeneous components. This technique involves direct-write deposition of multiple, patterned powder materials followed by laser processing. The direct-write deposition system features miniature hopper-nozzles for depositing dry powdered materials by gravity or by high frequency vibration-assisted flow onto a movable substrate. A dual wavelength laser processing workstation was used to consolidate the deposited pattern to desired densities. The feasibility of this concept was proved by direct-writing and laser processing various powder material patterns.

The great development of Solid Freeform Fabrication (SFF) techniques from their introduction into the market, more than 20 years ago, has fueled their diffusion in the mechanical sector to the point that they are today an indispensable component of the process of designing, engineering and producing a mechanical parts.

At the same time, these techniques found application in different and even distant sectors, like biomedicine or architecture. This lead to the necessity of developing SFF processes suitable for materials different from those they were at the beginning thought for. Such techniques, taken from the original ones or entirely developed ex-novo, allowed for a surprising differentiation of the applications.

The fabrication of ceramic parts by SFF techniques is a relatively new field which is widening the role of such materials in sectors not traditionally covered.

The present paper reports a state of the art of the techniques that appear more effective for the production of ceramic goods, with representative or even functional properties.

Further, some results of 3D Printing experiments of alumina parts will be presented.

The use of electro-hydro-dynamic (EHD) forces to generate highly charged coaxial jets of immiscible fluids, with diameters in the micro and nano regime, has unravel itself as a very interesting choice for producing complex nanostructures from a vast variety of precursors, provided they can solidify, polymerize or gel, in times comparable or shorter than the living time of the coaxial nanojet. For time ratios larger than one, the result of the process are micro or nanocapsules, while for time ratios smaller than one coaxial nanofibers are produced. We show examples of both situations, with organic and inorganic precursors. On the other hand, realization of the process in a liquid bath opens the door to production of controlled micro and nanosized complex emulsions.

Solid freeform fabrication (SFF) processes such as three-dimensional printing (3DP) and selective laser sintering (SLS) produce porous bodies that must be densified for many applications. New homogenous infiltration techniques can produce dense, homogenous parts of selected standard alloys, but the increased infiltration temperature dramatically increases creep deflection under self-weight. This paper reports on a method that improves dimensional stability by reducing creep deflection rates at high temperature. This method is applicable to all metal skeletons that must be strengthened without increasing shrinkage. In this method, the skeletons are reinforced by the addition of nanometer-sized particles dispersed in a liquid. The liquid is applied to the structure either during 3DP printing or after forming (3DP, SLS, pressing). The liquid is then evaporated, depositing the metal in the skeleton. The metal nanoparticles are sintered to density below the sintering temperature of the micron-scale skeleton particles. This concept is demonstrated using a suspension of 8–10 nm iron particles infiltrated into lightly sintered porous steel skeletons. When heated with an unsupported overhang to a typical infiltration temperature, creep deflection was reduced 50–80% with 0.5–1 wt% added metal.

The performances achieved by Rapid Prototyping techniques are progressively leading towards Rapid Manufacturing, that is the capability to produce end products, directly from the CAD model. Even so, the diffusion of these techniques is hardly supported by scientific knowledge about the micro-mechanisms ruling the macroscopic performances of the part. In the present research, mechanical performances of new materials produced by Direct Laser Sintering technique have been studied: a Polyamide and an innovative Polyamide-Aluminium composite (Alumide). Specimens were produced with different orientations in regard to powder deposition plane and laser path, to investigate how the manufacturing anisotropy affects the part performances.