Latest ArticlesThe thinning is a trend in the development of high-end electrical steel. Although its iron loss can be further reduced, the larger cold rolling reduction and the surface effect can influence the microstructure and texture of the final product, thereby affecting the magnetic properties. The two-stage cold rolling method can optimize the texture and increase the proportion of {100} and Goss textures. The influence of processing parameters on the microstructure, texture, and magnetic properties of a 0.10 mm thick ultra-thin non-oriented electrical steel is investigated by the two-stage cold rolling method, with a focus on the role of surface effects during prolonged holding. The results show that cube and Goss textures coexist in the final sheets produced by the two-stage cold rolling method. Furthermore, when the combined reduction from the two stages falls within the range of approximately 75% to 81%, the resulting texture and magnetic properties are superior to those of samples with reduction combinations of 90%/50% and 50%/90%. Within the temperature range of 840-920 ℃, the influence of time on grain growth is greater than that of temperature, and grain growth is affected by the surface effect in all cases. During isothermal annealing at 920 ℃, the 0.1 mm thick sample exhibits a more significant surface effect compared to the 0.27 mm thick sample, meaning grain growth is significantly hindered; the average grain size after the annealing for 60 min could not exceed the sheet thickness of 100 μm. In contrast, the average grain size of the 0.27 mm thick sheet grows to 175 μm.
The mechanical properties of polymer matrix composites often decrease due to hygrothermal environment. The hygrothermal aging tests and the compression tests are carried out before and after aging on the T700/BP9916 composites plate with open-hole, and the open-hole compression(OHC) strength is obtained. The residual stress distribution in the specimen after hygrothermal aging is simulated by ABAQUS software. Based on the hygrothermal expansion behavior and linear relationship between mechanical properties and the moisture absorption, OHC tests before and after hygrothermal aging are simulated. The results show that the moisture absorption of the T700/BP9916 composites have typical Fick diffusion behavior, and the maximum load of the OHC after hygrothermal aging decreases by approximately 5.2%. The internal stress caused by hygrothermal aging is very small and have no impact on the strength. The relative mass increment-time curve of moisture absorption obtained from the FEM simulation is in good agreement with the experimental. The relative error of maximum load of OHC test between the simulated and the experimental value is only 0.88% with non-hygrothermal aging, and the relative error is 6.21% during the hygrothermal environment. The increase in error is due to the fact that only the linear relationship between hygrothermal effect and the linear decline of material properties is considered in the simulation calculation.
8%(mass fraction)Y2O3 partially stabilized zirconia (8YSZ) is a currently commonly-used top-coat material for thermal barrier coatings (TBCs) applied to turbine blades in aero-engines. However, its volume change induced by high-temperature phase transitions above 1200 ℃ can easily lead to cracking and failure of TBCs. Sc2O3 is employed as an alternative stabilizer to fabricate 8%Sc2O3-92%ZrO₂(mole fraction) ceramics (8SSZ) via a solid-state synthesis method. The thermophysical properties of 8SSZ and conventional 8YSZ, including thermal expansion coefficient (CTE), thermal conductivity, and high-temperature phase/grain stability, are systematically compared. The results show that after heat treatment at 1400 ℃ in a muffle furnace, the CTE of 8SSZ measured by a dilatometer ranges from 8.91×10-6 K-1 to 10.7×10-6 K-1, which is comparable to that of 8YSZ. Thermal conductivity tests reveal that 8SSZ exhibits a thermal conductivity of 2.59 W/(m·K), approximately 20% lower than that of 8YSZ. X-ray diffraction (XRD) and scanning electron microscopy (SEM) results demonstrate that 8SSZ maintains phase stability without phase transitions after 500 h at 1400 ℃, outperforming 8YSZ in high-temperature phase stability. However, 8SSZ still exhibits the issue of excessive grain growth.