Effect of KNO3 Molten Bath Na Enrichment on the Mechanical Performances of Ion-exchanged Soda-Lime-Silicate Glass

Systematic doping of pure molten KNO3 bath by sodium nitride was used to analyze the effect of salt poisoning on the mechanical performances of chemically tempered soda-lime-silicate float glass. The ion-exchange process appears partially influenced by the presence of limited amount of Na in the potassium nitride bath. The interdiffusion coefficient and the penetration depth of K are invariant for NaNO3 content up to 5 wt%; conversely, the surface concentration of potassium scales with the purity of the bath, and this accounts for different compressive residual stress. Nevertheless, the overall reinforcement associated to the final strength does not show clear dependence on the used bath mainly because of the large scatter in the surface flaws sizes, as typically observed in glass

Electric Field-Assisted Ion Exchange of Borosilicate Glass Tubes

In this work, DC electric field-assisted ion exchange was carried out to enhance the sodium-potassium inter-diffusion and improve the mechanical performance of borosilicate glass. Electric fields with intensity varying between 100 V cm-1 and 3000 V cm-1 were applied in both direct and inverted polarizations. Four point bending test and the Vickers indentation method were used to characterize the mechanical properties. Energy dispersion x-ray spectroscopy was carried out to determine the potassium concentration within the surface layers of the samples

Novel method for the identification of the maximum solid loading suitable for optimal extrusion of ceramic pastes

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Spark plasma sintering of alumina/yttria-doped silicon carbide

AbstractSilicon carbide possesses exceptional mechanical and thermal properties, but its densification by conventional sintering is often very difficult. In the present work, silicon carbide was consolidated by spark plasma sintering in the presence of alumina and yttria. The results pointed out that the use of a single oxide does not enhance the sintering kinetics significantly, while the contemporaneous addition of both oxides has a beneficial effect on densification, with a relative density increase of about 10%. Interestingly, the oxide doping allows to double the room‐temperature flexural strength

Design of inorganic polymer mortar from ferricalsialic and calsialic slags for indoor humidity control

Amorphous silica and alumina of metakaolin are used to adjust the bulk composition of black (BSS) and white (WSS) steel slag to prepare alkali-activated (AAS) mortars consolidated at room temperature. The mix-design also includes also the addition of semi-crystalline matrix of river sand to the metakaolin/steel powders. The results showed that high strength of the steel slag/metakaolin mortars can be achieved with the geopolymerization process which was particularly affected by the metallic iron present into the steel slag. The corrosion of the Fe particles was found to be responsible for porosity in the range between 0.1 and 10 μm. This class of porosity dominated (~31 vol %) the pore network of B compared to W samples (~16 vol %). However, W series remained with the higher cumulative pore volume (0.18 mL/g) compared to B series, with 0.12 mL/g. The maximum flexural strength was 6.89 and 8.51 MPa for the W and B series, respectively. The fracture surface ESEM observations of AAS showed large grains covered with the matrix assuming the good adhesion bonds between the gel-like geopolymer structure mixed with alkali activated steel slag and the residual unreacted portion. The correlation between the metallic iron/Fe oxides content, the pore network development, the strength and microstructure suggested the steel slag's significant action into the strengthening mechanism of consolidated products. These products also showed an interesting adsorption/desorption behavior that suggested their use as coating material to maintain the stability of the indoor relative humidity

Effect of the Precipitating Agent on the Synthesis and Sintering Behavior of 20 mol %

Nanocrystalline 20 mol% samaria-doped ceria powders (Ce0.8Sm0.2O1.9) were synthesized by coprecipitation techniques using various precipitating agents in aqueous solution: ammonia, ammonium carbonate, tetramethylammonium hydroxide, and urea. The synthesized powders after calcination at 600°C possess a fluorite structure with nanometric size although they are characterized by a very different morphology and degree of agglomeration. Remarkable differences appear in the sintering behavior, especially because of the presence of hard agglomerates. The precipitating agent has therefore a crucial role in the coprecipitation process, which influences the morphology of the powders and in turn the sintering behavior. The obtained results clearly reveal that ammonium carbonate and urea are the best precipitating agents to obtain final dense products after sintering

A comprehensive study of custom-made ceramic separators for microbial fuel cells: Towards "living" bricks

Towards the commercialisation of microbial fuel cell (MFC) technology, well-performing, cost-effective, and sustainable separators are being developed. Ceramic is one of the promising materials for this purpose. In this study, ceramic separators made of three different clay types were tested to investigate the effect of ceramic material properties on their performance. The best-performing ceramic separators were white ceramic-based spotty membranes, which produced maximum power outputs of 717.7 ± 29.9 µW (white ceramic-based with brown spots, 71.8 W·m−3) and 715.3 ± 73.0 µW (white ceramic-based with red spots, 71.5 W·m−3). For single material ceramic types, red ceramic separator generated the highest power output of 670.5 ± 64. 8 µW (67.1 W·m−3). Porosity investigation revealed that white and red ceramics are more porous and have smaller pores compared to brown ceramic. Brown ceramic separators under performed initially but seem more favourable for long-term operation due to bigger pores and thus less tendency of membrane fouling. This study presents ways to enhance the function of ceramic separators in MFCs such as the novel spotty design as well as fine-tuning of porosity and pore size

Triggering the catalytic activity of SrTiO3-based ceramics by flash sintering

Confinement of charge carriers in nanoscopic systems has revealed to be an effective strategy to confer ceramic materials unconventional conductive properties by exploiting particle size effects and interfaces characteristics[1]. Strontium titanate (SrTiO3) is a piezoelectric oxide that requires to be doped by acceptor species (e.g. Fe substitution of Ti centers) in order to acquire fair chemical reactivity[2]. Please click Additional Files below to see the full abstract