Metal injection molding (MIM) is a net-forming technology for manufacturing miniature metal parts, which can improve the manufacturing accuracy of complex-shaped parts. In this study, aluminum stearate was used to modify the 17-4PH stainless steel powder, the binder was composed of (PMMA) and (PEG) with the volume ratio of 7:3. The effects of aluminum stearate surfactant amount on the feedstock viscosity, water debinding rate and thermal debinding shape were studied. The results showed that the coating of aluminum stearate breaks the agglomeration between the powders and decreases the viscosity of the feedstock. When the addition of aluminum stearate was 0.6wt% of the powder mass, the melt index, density and flexural modulus of the feedstock were 81.5 g/10 min, 5.44 g/cm3, and 1643Mpa, respectively, and the thermal debinding shape retention was the best of all debinded parts. However, too much aluminum stearate makes the feedstocks thicker and the green part weaker.
This work aims to provide useful insights into the thermal debinding kinetics of gelcast ceramic parts, especially for debinding kinetics prediction involving heat preservation. Debinding experiments were conducted in a differential thermogravimetric analyzer at five heating rates (5, 8, 10, 15, and 20 °C/min) in the temperature range of 35–900 °C under an air atmosphere. The conversion (α) and pyrolysis rate (dα/dT) data were simulated using a modified independent parallel reaction (IPR) model and a multiple normally distributed activation energy model (M-DAEM). Their validity was assessed and compared by checking the agreement between the experimental results and the prediction capability. The results showed that both the modified IPR model and M-DAEM had high predictability for thermal debinding kinetics under linear heating conditions. The fitting quality parameters (Fit) were less than 1.406 and 1.01%, respectively. The activation energies (Ei, i = 1, 2, 3, 4, and 5) calculated by the M-DAEM ranged from 153.312 to 217.171 kJ/mol. The relationships between Ei of pseudo components 1 to 5 calculated by the modified IPR model were a function of the conversion rate. The Ei values were E1(α) = 116.750 + 11.153α – 26.772α2 + 4.362α3 kJ/mol, E2(α) = 139.595 – 66.162α + 75.702α2 – 38.041α3 kJ/mol, E3(α) = 190.854 + 135.755α – 214.801α2 + 116.093α3 kJ/mol, E4(α) = 64.068 + 280.086α – 380.270α2 + 264.724α3 kJ/mol, and E5(α) = 188.257 – 77.086α + 74.129α2 – 48.669α3 kJ/mol, respectively. However, it is noteworthy that the α and dα/dT curves predicted by the modified IPR model with a deviation of less than 8% were better than those predicted by the M-DAEM for the linear thermal debinding process with the holding stage. Accordingly, it is believed that the proposed modified IPR model is suitable for describing the thermal debinding kinetics involving the heat preservation of gelcast green parts.
3D printing is capable of fabricating glass components with complex shapes that are challenging for traditional processing techniques. Here, we describe a paradigm of 3D printing of centimeter-sized glass aspheric lenses by Digital Light Processing (DLP). The printed lenses were post-processed using spin coating technique to reduce the layered structures. Our process involved the use of a glass slurry composed of UV-curable resins and silica nanoparticles, with the printed part undergoing thermal debinding and sintering to achieve transparency. The glass slurry exhibited significantly higher viscosities near the solid-liquid interface, which can result in a resin tray failure when applying a layer thickness below 50 μm in the DLP process. The printed lens exhibited a smooth surface with RMS < 15 nm, a surface profile deviation <170 μm and an imaging resolution of 45.3lp/mm.
危险品化学品经营许可证（带存储）