GLASS-COATED MICROWIRES FOR COMPOSITES

In this paper, solutions for two problems are proposed. One of the problems is associated with increasing the strength of objects, for instance, the strength of windows in industrial buildings and dwelling houses. The other problem is related to electromagnetic shielding. Both of these problems are related to the protection form terrorist acts, since terrorists make use of concentrated electromagnetic pulses to destroy computers or other electronic equipment. The proposed solutions are based upon the manufacturing of glass windows reinforced with cast glass-coated amorphous micro- and nanowires (CGCAMNWs) having a special composition and structure, which increases their tensile strength against mechanical destruction, on the one hand, and imparts them with shielding properties against electromagnetic radiation, on the other hand. The CGCAMNW materials are of interest from both theoretical and practical points of view.

On the flexural strength and stiffness of cast glass

Cast glass has great potential for diverse load-bearing, architectural applications; through casting, volumetric glass components can be made that take full advantage of glass’s stated compressive strength. However, the lack of engineering, production and quality control standards for cast glass and the intertwined ambiguities over its mechanical properties-particularly due to the variety in chemical compositions and the lack of understanding of the influence of flaws occurring in the glass bulk-act as an impediment to its wide-spread application. Addressing the above uncertainties, this work studies a total of 64 silicate-based glass specimens, prepared in 20 * 30 * 350 mm beam size, either by kiln-casting at relatively low forming temperatures (970–1120 $$^{\circ }$$ ∘ C), or by modification of industrially produced glass. For the kiln-casting of the specimens, pure and contaminated recycled cullet are used, either individually or in combination (composite glasses). The defects introduced in the glass specimens during the casting process are identified with digital microscopy and qualitative stress analysis using cross polarized light, and are categorized as stress-inducing, strength-reducing or harmless. The Impulse Excitation Technique is employed to measure the Young’s modulus and internal friction of the different glasses. Differential Scanning Calorimetry is used on a selection of glasses, to investigate changes in the glass transition range and fictive temperature of the kiln-cast glasses due to the slower cooling and prolonged annealing. The four-point bending experiments are shedding light upon the flexural strength and stiffness of the different glasses, while the fractographic analysis pinpoints the most critical defects per glass category. The experiments show the flexural strength of cast glass ranging between 30–73 MPa, according to the level of contamination and the chemical composition. The measured E moduli by both methods are in close agreement, ranging between 60–79 GPa. The comparison of the flexural strength with prior testing of cast glass involving shorter span fixtures showed a decreasing strength with increasing size for the contaminated specimens, but similar strengths for pure compositions. The results highlight the versatile role of defects in determining the glass strength and the complexity that arises in creating statistical prediction models and performing quality control.

Rejuvenation by enthalpy relaxation in metallic glasses

Usually structural relaxation would lead to embrittlement in metallic glasses (MGs). Here, we show that rejuvenation of relaxed MGs is achieved simply by a thermal exposure at a temperature higher than the annealing temperature (but below glass transition temperature). The effect is driven by enthalpy relaxation (an endothermic reaction upon heating relaxed MGs). This rejuvenation lifts the energy state of the relaxed glass towards that of the as-cast glass. Importantly, we demonstrate that the plasticity and fracture toughness of the rejuvenated samples exceed those of the as-cast state. An analysis of the structural changes shows that the rearrangement of cluster connectivity at the medium-range length scale is responsible for the rejuvenation. Our finding is significant for the tailoring of the mechanical properties of metallic glasses.

Investigating the flexural strength of recycled cast glass

Currently, tons of high quality commercial glass are down-cycled or landfilled due to contaminants that prevent close-loop recycling. Yet, this glass is potentially a valuable resource for casting robust and aesthetically unique building components. Exploring the potential of this idea, different types of non-recyclable silicate glasses are kiln-cast into $$30\times 30\times 240$$ 30 × 30 × 240 mm beams, at relatively low temperatures (820–1120$$\,^{\circ }\hbox {C}$$ ∘ C ). The defects occurring in the glass specimens due to cullet contamination and the high viscosity of the glass melt, are documented and correlated to the casting parameters. Then, the kiln-cast specimens and industrially manufactured reference beams are tested in four-point bending, obtaining a flexural strength range of 9–72 MPa. The results are analysed according to the role of the chemical composition, level of contamination and followed casting parameters, in determining the flexural strength, the Young’s modulus and the prevailing strength-limiting flaw. Chemical compositions of favourable performance are highlighted, so as critical flaws responsible for a dramatic decrease in strength, up to 75%. The defects situated in the glass bulk, however, are tolerated by the glass network and have minor impact on flexural strength and Young’s modulus. The prerequisites for good quality recycled cast glass building components are identified and an outline for future research is provided.

Graphic Swim: 2D and 3D Printing in Glass Casting

This document is a report on developing processes to encourage flow of the graphic image in kilnformed glass. It is also a description and reflection on a body of artworks in glass in which new visual qualities were exposed through a mishap and turned into an aesthetic choice. The research links 2D print approaches to 3D printing and their integration in cast glass. It updates the author’s practice-based PhD research, a study that utilizes glass printing, cutting and fusing processes to combine the printed image within the glass object. The outcomes of the study can be organized under two approaches that have been developed, one appropriate to practical workshop teaching, and the other for the conceptualization and fabrication of new personal artworks.