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Additive manufacturing of components with enhanced characteristics to combine the geometrical flexibility of layer-by-layer manufacturing and the remarkable thermomechanical and optical properties of advanced materials has become a focus for research in the last decades. In this investigation, in-house developed Al 2 O 3 slurries mixed with either MgO or MgAl 2 O 4 were digitally light processed and the resulting green parts underwent slow thermal debinding at low heating rates to produce dense and stable brown samples, which were subsequently subjected to different sintering regimes to obtain translucent samples. Air sintering trials were conducted at 1700 °C and the effect of different heating rates and holding times at the sintering temperature were investigated. In addition, vacuum sintering at 1600 °C was conducted for the best conditions to assess the effect of an oxygen-reduced atmosphere. Geometrical dimensions and density data were collected at the brown and fired stages to observe their evolution through the process with the help of high-magnification optical microscopy. Scanning electron microscope (SEM) images of the sintered samples were collected to observe and characterise the obtained microstructure. In addition, X-ray diffraction (XRD) was used to identify the crystal structure and assess the insurgence of secondary phases. Finally, total transmittance and in-line transmittance were measured to evaluate the translucency level achieved by the produced sintered samples. Translucent alumina samples exhibiting a maximum total transmittance of 90.4% and a maximum real in-line transmittance (RIT) of 16.9% in the visible and near-infrared regions were fabricated. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: The aim of this paper is to optimise process conditions in micro injection moulding (μ−IM) to minimise shrinkage whilst maximising part mass. Method: A Design of Experiment (DoE) approach was implemented for studying the effect of five processing parameters on shrinkage and part mass. A multiple quality criteria based analysis was used to optimise the process. Results: Significant factors were found for shrinkage and part mass. Conclusions: The multiple quality criteria could be optimized, and this optimization validated experimentally. [Copyright &y& Elsevier]

Abstract: The aim of this paper is to provide a method for measuring shrinkage in micro injection moulded (μ-IM) parts – no standardised approach being reported as yet in the literature. This study investigates the feasibility of implementing the international standards used to investigate shrinkage in conventional (macro) moulding at the micro-scale. Following a similar experimental procedure to the relevant standards, micro-moulded polyoxymethylene (POM) specimens were produced, and the influence of processing parameters on their shrinkage was analysed using the design of experiment (DoE) approach. The analysis results showed that the methodology was capable of detecting factors that had a statistically significant effect on shrinkage at the micro-scale, in both parallel to, and normal to, the flow directions for moulding, post-moulding and total shrinkage. [Copyright &y& Elsevier]

Abstract: Rapid developments in microsystem technologies demand ceramic microcomponents of increasing geometrical complexity. State-of-the-art microfabrication routes of ceramics are either limited in geometrical complexity and/or high volume capabilities. This paper presents a process route by which ceramic microcomponents with relatively complex three-dimensional architectures could be realised by a high-volume technique. The proposed strategy, in which yttria-stabilised zirconia was implemented, combines the capabilities of insert-micromoulding, powder micro-overmoulding, catalytic debinding and sintering. The produced architectures demonstrate the capability of the technique to combine the high performance of ceramic materials with the dimensional accuracy and mass manufacturability of powder micromoulding. [Copyright &y& Elsevier]