The effects of sodium hexametaphosphate (SHMP) addition on the dispersion and hydration of calcium aluminate cement were investigated, and the relevant mechanisms discussed. The content of SHMP and the adsorption capacity of SHMP on the surface of cement particles were estimated using plasma adsorption spectroscopy and the residual concentration method. The rheological behavior of hydrate, ζ-potential value of cement particles, phase transformation and the microstructure of the samples were determined by coaxial cylinder rheometer, zeta probe, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicate that SHMP readily reacted with Ca²⁺, forming complexes [Ca₂(PO₃)₆]²⁻ ions which were subsequently adsorbed onto the surfaces of cement particles. When the content of SHMP was 0.05%, the adsorption ratio reached 99%. However, it decreased to 89% upon further increasing the addition of SHMP to 0.4%. The complexes [Ca₂(PO₃)₆]²⁻ adsorbed onto the surfaces of cement particles inhibited the concentration of Ca²⁺ and changed ζ-potential, resulting in enhanced electrostatic repulsive force between the cement particles and reduced viscosity of cement-water slurry. The experimental results indicate that the complexes [Ca₂(PO₃)₆]²⁻ covering the surfaces of cement particles led to a delayed hydration reaction, i.e., they extended the hydration time of the cement particles, and that the optimal addition of SHMP was found to be about 0.2%.

Mullite–corundum ceramics are pivotal in heat transfer pipelines and thermal energy storage systems due to their excellent mechanical properties, thermal stability, and chemical resistance. Establishing relationships and mechanisms through traditional experiments is time-consuming and labor-intensive. In this study, gradient boosting regression (GBR), random forest (RF), and artificial neural network (ANN) models were developed to predict essential properties such as apparent porosity, bulk density, water absorption, and flexural strength of mullite–corundum ceramics. The GBR model (R² 0.91–0.95) outperformed the RF and ANN models (R² 0.83–0.89 and 0.88–0.91, respectively) in accuracy. Feature importance and partial dependence analyses revealed that sintering temperature and K₂O (~0.25%) positively affected bulk density while negatively influencing apparent porosity and water absorption. Additionally, sintering temperature, additives, and Fe₂O₃ (optimal content ~5% and 1%, respectively) were positively related to flexural strength. This approach provided new insight into the relationships between feedstock compositions and sintering process parameters and ceramic properties, and it explored the possible mechanisms involved.

Ion doping can modify the cell structure, which is one of the effective methods to improve electrochemical performance. However, there is a lack of research on F- and Cl-doped LiNi_0.8Co_0.1Mn_0.1O₂. In this paper, the effects of F and Cl doping on the electrochemical properties and cell structure of LiNi_0.83Co_0.08Mn_0.08O₂ during the process of lithium removal were studied by a first-principles calculation based on density functional theory. The results show that F doping reduces the change in cell parameters and improves the stability of cell structure. On the contrary, Cl doping reduces the stability of the cell structure. F doping increased the delithiation potential from 3.64 V to 3.76 V, and the delithiation potential was relatively stable in the process of delithiation. Cl doping decreased the delithiation potential from 3.64 V to 3.26 V, and the voltage stability became worse. F doping can effectively reduce the occurrence of Li–Ni mixed arrangement phenomena. Meanwhile, Cl doping can inhibit the formation of oxygen vacancies, and the further degradation of the materials. F doping broadens the Li⁺ diffusion channel away from the doping site and improves the diffusion rate of Li⁺ in this layer. In the vicinity of F-doped sites, the electrostatic field in the process of Li⁺ diffusion is enhanced and the diffusion of Li⁺ is reduced. Cl doping increases the diffusion barrier of Li⁺ and slows down the diffusion rate of Li⁺.

A three-dimensional numerical model of the vacuum sintering furnace was established, combined with the custom program of temperature-voltage feedback regulation. Through simulationand experimental validation, the heating and holding stage as well as the thermal hysteresis phenomenon of the furnace were analyzed, a dimensionless quantity of hysteresis temperature difference was proposed and calculated, the distribution of the electric field and temperature uniformity of the furnace were discussed in detail, while the structural improvement approach was proposed based on simulation. The results show that: during the heating process, the maximum of thermal hysteresis temperature difference between the graphite cylinder and the heating tube is 0.4. The relative error between the simulation and measurement is within 4%, which verifies the accuracy of the model. By optimizing the structure of the heating tube and graphite base plate, the thermal hysteresis effect of the furnace can be effectively reduced, the surface load and the temperature difference between the surface of the heater can be significantly reduced, the temperature field and uniformity of the heating zone can be improved.

In this paper, the effect of a sodium tripolyphosphate (STPP) addition on the dispersion and hydration of pure calcium aluminate cement (PCAC) was investigated, and the corresponding mechanism of effect was studied. The effects of STPP on the dispersion, rheology, and hydration processes of PCAC and its adsorption capacity on the surface of cement particles were analysed by measuring the 𝜁-potential on the surface of cement particles, the changes in the concentrations of elemental P and Ca²⁺ ions in a solution at different STPP additions. The experimental results show that STPP easily complexes with Ca²⁺ ions to produce the complex [CaP₃O₁₀]³⁻ adsorbed on the surface of cement particles, which changes the potential on the surface of cement particles and increases the electrostatic repulsive force between cement particles, thus improving the dispersion and rheology of cement. At the same time, the contact area between cement particles and water is reduced, which hinders the hydration process and makes the time of hydration process longer. A comprehensive analysis shows that the best effect of STPP on pure calcium aluminate cements is achieved when the addition of STPP is 0.2%. This study can provide a reference for the addition of water-reducing agents in refractory castables as well as improving the quality of refractory materials.