A kind of multiscale β-sialon grain-reinforced Al₂O₃ matrix composite ceramic tool material, named ASN, was prepared and studied. For the ASN, β-sialon (molecular formula: Si₄Al₂O₂N₆) was synthesized in situ by a hot-pressing and solid-solution reaction process. A total of six samples were prepared at varying sintering temperatures and holding times under vacuum conditions. The solid solution reaction mechanism of β-sialon, the phase composition, mechanical properties, microstructure, and strengthening and toughening mechanisms of the composite ASN were investigated. As a result, within the experimental parameters, an optimal ASN tool material was obtained under a pressure of 32 MPa and at a temperature of 1550 °C for 20 min. The tested mechanical properties of the optimal sample were as follows: flexural strength 997 ± 59 MPa, fracture toughness 6.4 ± 0.3 MPa·m^1/2, Vickers hardness 18.2 ± 0.4 GPa, and relative density 98.1 ± 0.2%. According to crystal defect theory, the solid solution reaction mechanism of in-situ-synthesized β-sialon in an Al₂O₃ matrix involves a double mechanism of unequivalence (or hetero-valence) and interstitial filling. The multiscale β-sialon grains mainly consisted of four grains, which were elongated β-sialon grains with a diameter of 0.3–0.4 μm and an aspect ratio of 6–9, elongated β-sialon grains with a diameter of 70 nm and an aspect ratio of 10, β-sialon whiskers with a diameter of 0.2 μm and an aspect ratio of 12–15, and intragranular β-sialon whiskers with a diameter of 70 nm. The mechanical properties were improved due to strengthening and toughening mechanisms, such as mixed structure mode (intergranular and transgranular), elongated grain pullout, interface bonding, crack reflection, pinning, and bridging.

To address the poor thermal shock resistance and high brittleness of traditional ceramic tools, a novel Si₃N₄/Sc₂W₃O₁₂ (SNS) composite ceramic material was developed via in situ synthesis using WO₃ and Sc₂O₃ as precursors and consolidated by spark plasma sintering. Sc₂W₃O₁₂ with negative thermal expansion was introduced to compensate for matrix shrinkage and modulate interfacial stress. The effects of varying Sc₂W₃O₁₂ content on thermal expansion, residual stress, microstructure, and mechanical properties were systematically investigated. Among the compositions, SNS3 (12 wt.% Sc₂W₃O₁₂) exhibited the best overall performance: relative density of 98.8 ± 0.2%, flexural strength of 712.4 ± 30 MPa, fracture toughness of 7.5 ± 0.3 MPa·m^1/2, Vickers hardness of 16.3 ± 0.3 GPa, and an average thermal expansion coefficient of 2.81 × 10⁻⁶·K⁻¹. The formation of a spherical chain-like Sc-W-O phase at the grain boundaries created a “hard core–soft shell” interface that enhanced crack resistance and stress buffering. Cutting tests showed that the SNS3 tool reduced workpiece surface roughness by 32.91% and achieved a cutting distance of 9500 m. These results validate the potential of this novel multiphase ceramic system as a promising candidate for high-performance and thermally stable ceramic cutting tools.

With the deepening of the research on PPG (Photovoltaic Power Generation), the power generation technology is becoming more and more mature, and the power generation cost is getting lower and lower, so it is an inevitable trend to reduce it to a level competitive with the thermal power generation price. The result of voltage instability will lead to system collapse or large-scale power failure. Therefore, this paper launches the simulation research on voltage response model of new energy PPG system. GA(genetic algorithm) is adopted. By analyzing the advantages and disadvantages of GA, IGA(Improved GA) is used to make up for the shortcomings of GA, and IGA is applied to distribution network RPO(Reactive power optimization). To improve the universality of GA population, effectively prevent premature phenomenon in operation and greatly improve the convergence speed of the algorithm, this paper introduces the elite reverse learning mechanism into GA, which can obviously optimize the initial population and iterative process in GA. The simulation results show that after DG( distributed generation) is connected to the distribution network, the distribution network loss accounts for 73. 39% of the total power system loss. The average voltage unit value of the lines in the system is increased from 0.953 to 0.969. The improved GA is superior to the original GA in all aspects, and the feasibility and superiority of the improved GA in the application of RPO are verified.

This study addresses the unclear damage mechanisms of TiAlSiN-coated tools during high-speed milling of GH4169 by integrating milling experiments with finite element simulations, and establishes a thermo-mechanical coupled damage prediction model that accounts for the superposition effect of cyclic loads. Cutting experiments show that with increasing cutting speed, the rake face damage evolves from peeling and abrasive wear to comb-shaped thermal cracks, mechanical cracks, and large-area peeling, accompanied by a significant reduction in tool life. Simulations reveal that the superposition of residual thermal compressive stress during the idle-cutting phase with mechanical stress in the subsequent cutting cycle forms alternating loads, which is the fundamental cause of thermo-mechanical fatigue crack initiation. The XFEM-CEM coupled model indicates that at higher cutting speeds, the maximum principal stress increases, promoting easier coating crack initiation and greater interfacial debonding. The thermo-mechanical coupled damage prediction model, improved by incorporating a temperature-modified strength threshold and a thermal acceleration factor, yields predictions consistent with experimental results, providing a theoretical basis for process parameter optimization and tool life prediction.