Vol 7 No 1 (2025)

• Spent Potlining from Aluminium Electrolysis-Are Cells with Vertical Inert Electrodes a Solution?

  Jón Hjaltalín Magnússon, Halvor Kvande

  Spent potlining (SPL) is a term used in the aluminium industry for the spent cathode lining materials of industrial electrolysis cells. SPL is the cathode and sidewall materials that are removed from a cell after being shut down. The treatment of spent potlining is an environmental problem that has been a challenge for a long time and it needs to be solved. Sodium ions are the main carrier of electrical current through the molten cryolite bath during electrolysis, and a small amount of sodium metal is formed as part of the cathode reaction. Sodium penetrates the porous horizontal carbon cathode blocks in the bottom of the cell and causes swelling of the carbon material. With the present cell design it is not possible to eliminate this sodium interaction, and the only way to avoid it is to use a different cell design. The present paper discusses whether the use of cells with vertical inert electrodes will give less sodium penetration in the carbon part of the cell.

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• Cauchy Pressure and Valence Electron Concentration Dominated Hardness of Multi-principal Element Carbides Ceramics

  Zhigang Ding

  Recent studies indicate that multi-principal element carbides (MPECs) ceramics can simultaneously possess high hardness and high toughness, which have potential applications in industrial fields. Nevertheless, microstructural origins of the excellent hardness and toughness combination remain unclear. In present study, the hardness of 38 derivatives based on (Ti-Zr-Hf-V-Nb-Ta)C MPECs were researched by density functional theory calculations. We found that that the non-linear equation combination by Cauchy pressure P_c and valence electron concentration (VEC) show high prediction accuracy (R² = 0.91) with DFT values. The multivariate regression surface of hardness reveals that high hardness is often associated with high VEC and low Cauchy pressure, which can be used to predict the hardness of MPECs.

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• Influence of the Addition of Niobium Pentoxide on the Structural Properties of Hydroxyapatite

  José Adauto da Cruz, Rogério Ribeiro Pezarini, Stephen Rathinaraj Benjamin, Rogério Ribeiro Pezarini, Paulo Maria de Oliveira Silva, Antonio Jefferson Mangueira Sales, Fernandes GraçaManuel Pedro

  The study focused on investigating the properties of composites made from natural hydroxyapatite (HAp, Ca₁₀(PO₄)₆(OH)₂) sourced from tilapia fish bones (Oreochromis niloticus) and niobium pentoxide (PNb, Nb₂O₅). The effects of PNb concentration and sintering temperature were examined. Composites were created using a constant pressure of 450 MPa following the formula (100-x)HAp + (x)PNb, with x varying in increments of 10%, and then sintered at temperatures ranging from 700 to 1300 °C. X-ray diffraction (XRD) analysis showed the formation of new phases based on the PNb concentration and temperature. Rietveld refinement confirmed a strong fit with experimental data, supporting the accuracy of the model parameters. Fourier Transform Infrared Spectroscopy with Photoacoustic Detection (FTIR-PAS) revealed the disappearance of the OH^- functional group at 3572 cm^-¹. Raman spectroscopy results were consistent with XRD findings. Scanning Electron Microscopy (SEM) showed complex microstructures influenced by composition, sintering temperature, and phase interactions, with liquid-phase sintering contributing to microstructural changes. Energy Dispersive X-ray Spectroscopy (EDS) provided semiquantitative analysis, detecting the primary elements Ca, P, and Nb, along with smaller amounts of Mg and Na. The Vickers Hardness (VH) measurements indicated that PNb concentration significantly affects the mechanical properties of the composite. The study suggests that HAp/PNb composites, influenced by temperature and PNb concentration, hold great potential for use in orthopedic and dental biomaterials.

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• Polymer Waterproof Materials and Their Application in Engineering Construction

  Zhan-Cui Wu, Zhen-Yu Mao, Qian Wang, Xiao-Rong Zhang

  This paper focuses on polymer waterproof materials, which are typically based on synthetic rubber or resin and are classified into sheet membranes and coatings. Their core properties include physical-mechanical strength and weather resistance, while performance can be further enhanced through modification technologies such as nanotechnology and material compounding. The study elaborates on their application in building roofs, underground spaces, transportation infrastructure, and projects under special environmental conditions. Innovative application approaches are also explored, including the establishment of standardized construction systems that integrate process specifications, quality inspection, and digital management; the development of multi-material collaborative waterproofing systems; and the adoption of intelligent monitoring technologies such as fiber-optic sensing, wireless humidity monitoring, and UAV inspection to enable real-time detection of waterproofing performance. These strategies provide comprehensive waterproofing solutions for engineering construction.

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• Impacts of Hydrogeological and Environmental Geological Disasters on the Ecological Environment and Restoration Measures

  Dan-Yi Cheng

  Hydrogeological and environmental geological disasters, encompassing various types such as landslides, debris flows, and ground collapses, result from the combined effects of natural factors and human engineering activities. This paper focuses on these disasters, beginning with an introduction to common types including landslides and debris flows, land subsidence and collapse, and reservoir-induced seismicity. It provides an in-depth analysis of the multifaceted impacts of these disasters on the ecological environment, covering hydrological systems, soil environment, biodiversity, and long-term changes in geological structures. In response to these impacts, a series of ecological restoration measures are proposed, including engineering restoration, bioremediation, combined physical-chemical remediation, reconstruction of wetland ecosystems, and optimization of monitoring and early warning systems. The aim is to provide theoretical support and practical references for mitigating the damage caused by hydrogeological and environmental geological disasters to the ecological environment and achieving sustainable ecological development.

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