There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

This study investigated the corrosion behavior of calcium zirconate crucibles during vacuum induction melting of Ti–6Al–4V. Due to its production method the fused calcium zirconate raw material contained a significant amount of cubic zirconia as a second phase. Thus, the raw material composition was adjusted by adding calcium hydroxide as a calcia precursor during the crucible production. Crucibles with four different compositions were tested in contact with Ti–6Al–4V melts. The corroded crucibles were investigated by SEM in combination with EDX and EBSD, whereas a dissolution of the zirconia phase by the alloy melt was observed. The calcium zirconate phase however remained unaffected. This result compared well with the determined zirconium and oxygen contamination of the melts, which decreased substantially with a higher calcium zirconate content of the crucibles. An overstoichiometric composition in terms of calcia, however, caused the evaporation of calcia and should therefore be avoided.

Investigating the corrosion resistance of calcium zirconate in contact with titanium alloy melts

The massive generation of electronic waste (e-waste) and the informal recycling of e-waste are serious concerns in China. As a hazardous waste stream, e-waste calls for sustainable management practices to avoid adverse effects on environment and health. However, consumers' awareness and active participation are needed to make e-waste management successful. Therefore, this study is an exploratory attempt to investigate young consumer awareness, knowledge, and participation in sustainable e-waste management practices. Meanwhile, the study reviews the current situation of e-waste recycling, its related legislative framework, and practices in China. The survey revealed that the respondents have keen environmental consciousness, while they have low awareness about e-waste-related rules and regulations, recycling programs, and the formal and informal recycling sector. The findings provide valuable insights for practitioners in order to promote environmental awareness and sustainable e-waste management practices among young consumers in China.

Assessing young consumers' awareness and participation in sustainable e-waste management practices: a survey study in Northwest China.

Performance improvement of MgO-CaO refractories by the addition of nano-sized Al2O3

This study investigates chemical, physical, mechanical, and thermomechanical properties of calcium zirconate (CaZrO3) refractories. The applied fused raw material contained some residual cubic zirconia, which impairs the corrosion resistance of CaZrO3 refractories. To adjust the stoichiometry, CaCO3 was added. Furthermore, stoichiometric amounts of CaCO3/monoclinic ZrO2 were added to promote an in situ pore formation without altering the phase composition. After firing cubic zirconia was only found in the coarse grained aggregates. CaCO3 additions increased the apparent porosity and reduced the thermal expansion coefficient due to the stoichiometric adjustment. Surprisingly, a higher porosity did not result in an improved thermal shock resistance, which can be attributed to a shift to larger pore sizes. This might cause a lower crack density, which is usually associated with a reduced thermal shock resistance. Future work will address the formation of smaller pores and the evaluation of the thermal shock resistance under practical conditions.

Influence of in situ phase formation on properties of calcium zirconate refractories

Studies to improve the hydration resistance of lime-based materials are reviewed. The methods described include densification of the lime aggregate by addition of sintering aids and surface treatment. Methods for assessing hydration resistance are also reviewed. Additions of ZrO2, TiO2 (including Ti chelating compounds) and rare earth oxides can improve the hydration resistance of CaO aggregate by, it is believed, enhancing solid state sintering without sacrificing refractoriness via formation of hydration resistant solid solutions. Fe2O3, Al2O3 (as well as Al chelating compounds and Al metal), CuO and V2O5, act as liquid forming aids. These additives improve the sintering of lime and subsequently the hydration-resistance via formation of liquids at high temperature which cool to produce hydration-resistant solids surrounding the lime polycrystals. However, the liquids formed may significantly reduce the refractoriness of lime materials, thus eroding their particular advantage. The same problem is...

Z. Li

Papers

Improving the hydration resistance of lime-based refractory materials