In this study, we developed a unique defect healing method for 3D printed ceramic compact via cold isostatic pressing (CIP) after debinding, and typical features of interlayer interface defects of 3D-printed zirconia compact were characterized and found to be reduced significantly. The characteristic sintering kinetics window and microstructure evolution of the healed sintered bodies were systematically investigated, which was found to be quite different from conventional shaping methods. The three sintering stages are probed by their feature microstructure details such as the mechanically flattening surface at the early sintering stage, the heterogeneous microstructure and high porosity in the interlayer interface region at the middle stage, and the slightly ripple-like structural features combined with the healed interlayer defects at the final stage. The evolution of the pore structure of the healed 3D printed bodies were traced and the mechanical properties such as the Young's modulus, hardness, and fracture toughness were measured to understand the significance of the heal effect. 相似文献
Thermosetting materials are widely used as encapsulation in the electrical packaging to protect the core electronic components from external force, moisture, dust, and other factors. However, the spreading and curing behaviors of such kind of fluid on a heated surface have been rarely explored. In this study, we experimentally and numerically investigated the spreading and curing behaviors of the silicone(OE6550 A/B, which is widely used in the light-emitting diode packaging) droplet with diameter of ~2.2 mm on a heated surface with temperature ranging from 25 ℃ to 250 ℃. For the experiments, we established a setup with high-speed camera and heating unit to capture the fast spreading process of the silicone droplet on the heated surface. For the numerical simulation, we built a viscosity model of the silicone by using the Kiuna's model and combined the viscosity model with the Volume of Fluid(VOF) model by the User Defined Function(UDF) method. The results show that the surface temperature significantly affected the spreading behaviors of the silicone droplet since it determines the temperature and viscosity distribution inside the droplet. For surface temperature varied from 25 ℃ to 250 ℃, the final contact radius changed from ~2.95 mm to ~1.78 mm and the total spreading time changed from ~511 s to ~0.15 s. By further analyzing the viscosity evolution of the droplet, we found that the decreasing of the total spreading time was caused by the decrease of the viscosity under high surface temperature at initial spreading stage, while the reduction of the final contact radius was caused by the curing of the precursor film. This study supplies a strategy to tuning the spreading and curing behavior of silicone by imposing high surface temperature, which is of great importance to the electronic packaging. 相似文献
It is of great significance to study the soil pore structure for soil reinforcement and ground treatment because it can be used to evaluate the solidification effect and explain the curing mechanism. The pore and compression characteristics of clay from Wuhan in China before and after solidification by ionic soil stabilizer (ISS) in different soil initial states were studied by the use of standard consolidation test, environmental scanning electron microscope analysis, specific surface area (SSA) test, and analysis by PCAS software. Results show that the influence sequence of soil initial states on the change of pore characteristics and ISS-solidification effectiveness was as follows: reducing initial water content + remolding soil > reducing initial water content > remolding soil > natural soil with high initial water content. Besides, loading can also increase the solidification effect. Compared to random and chaotic pore directions of natural clay, remolded solidified clay had a more certain direction after curing and compression. In addition, the total pore number and SSA decreased from 1190 to 756 by 36.47% and 109.690 m2/g to 87.837 m2/g by 19.92% respectively. Results indicate that ISS-clay solidification effect in practical engineering is closely related to the soil initial pre-curing state and can lead to the change of pore direction, decrease of pore number, reduction of pore size and porosity, and formation of larger aggregates.
This work intends to develop an online experimental system for screening of deoxynivalenol (DON) contamination in whole wheat meals by visible/near-infrared (Vis/NIR) spectroscopy and computer vision coupling technology. Spectral and image information of samples with various DON levels was collected at speed of 0.15 m s−1 on a conveyor belt. The two-type data were then integrated and subjected to chemometric analysis. Discriminant analysis showed that samples could be classified by setting 1000 μg kg−1 as the cut-off value. The best correct classified rate obtained in prediction was 93.55% based on fusion of spectral and image features, with reduced prediction uncertainty as compared to single feature. However, quantification of DON by quantitative analysis was not successful due to poor model performance. These results indicate that, although not accurate enough to provide conclusive result, this coupling technology could be adopted for rapid screening of DON contamination in cereals and feeds during processing. 相似文献
Waxy, normal and high-amylose maize starches were subjected to heat-moisture treatment (HMT) and then added to wheat flour (WF) in different ratios (1%, 5% and 10%). The properties of blends and their cooked noodles were studied to investigate the effects of HMT starches. The incorporation of HMT starch in WF led to an increase in swelling power, peak viscosity and breakdown and to a decrease in setback, thus inhibiting retrogradation, hence enhancing resultant noodle softness. Compared to the same addition ratio of native starch to WF, HMT starch led to higher tensile strength and extensibility in resultant noodles. WF with added HMT starch had higher resistant starch than with native starch. This study showed that addition of HMT maize starch has potential to bring nutritional benefits. However, it is necessary to select the proper blending ratio and amylose content of starch to add, in consideration of its effect on noodle quality. 相似文献