The objective of this study is to show the feasibility of producing SiC-aluminum composites by binder jetting 3D printing of SiC preforms and spontaneous infiltration by aluminum. SiC preforms fabricated using binder jetting 3D printing were subjected to several post-processing steps (including curing, depowdering, debinding, and sintering). Sintering was done at 1700°C and infiltration of aluminum was done at 1000°C, with both in a controlled nitrogen environment under a pressure of 25 psi. The bulk density of the sintered SiC preforms was increased by 14% after infiltration. X-ray diffraction and energy-dispersive X-ray spectroscopy confirmed the presence of aluminum in the SiC matrix. This paper is the first to report fabricating SiC-aluminum composites by binder jetting and infiltrating, providing a new approach to producing these composites with potential applications in aerospace and automotive industries
In this preliminary study, the long-term effects of calcium chloride crosslinking concentration on viability of 16HBE14o- human bronchial epithelial cells embedded in alginate-extracellular matrix (ECM) or alginate–methylcellulose–ECM hydrogels have been investigated. There is currently a limited understanding regarding the effects of crosslinking solution concentration on lung epithelial cells embedded in hydrogel. Furthermore, the effects of calcium chloride concentration in crosslinking solutions on other cell types have not been reported regarding whether the addition of viscosity and stiffness tuning agents such as methylcellulose will alter the responses of cells to changes in calcium chloride concentration in crosslinking solutions. While there were no significant effects of calcium chloride concentration on cell viability in alginate–ECM hydrogels, there is a decrease in cell viability in alginate–methylcellulose–ECM hydrogels crosslinked with 300 mM calcium chloride crosslinking solution. These findings have implications in the maintenance of 16HBE14o- 3D cultures with respect to the gelation of alginate with high concentrations of ionic crosslinking solution.
Biomass–fungi composite materials primarily consist of biomass particles (sourced from agricultural residues) and a network of fungal hyphae that bind the biomass particles together. These materials have potential applications across diverse industries, such as packaging, furniture, and construction. 3D printing offers a new approach to manufacturing parts using biomass–fungi composite materials, as an alternative to traditional molding-based methods. However, there are challenges in producing parts with desired quality (for example, geometric accuracy after printing and height shrinkage several days after printing) by using 3D printing-based methods. This paper introduces an innovative approach to enhance part quality by incorporating ionic crosslinking into the 3D printing-based methods. While ionic crosslinking has been explored in hydrogel-based bioprinting, its application in biomass–fungi composite materials has not been reported. Using sodium alginate (SA) as the hydrogel and calcium chloride as the crosslinking agent, this paper investigates their effects on quality (geometric accuracy and height shrinkage) of 3D printed samples and physiochemical characteristics (rheological, chemical, and texture properties) of biomass–fungi composite materials. Results show that increasing SA concentration led to significant improvements in both geometric accuracy and height shrinkage of 3D printed samples. Moreover, crosslinking exposure significantly enhanced hardness of the biomass–fungi mixture samples prepared for texture profile analysis, while the inclusion of SA notably improved cohesiveness and springiness of the biomass–fungi mixture samples. Furthermore, Fourier transform infrared spectroscopy confirms the occurrence of ionic crosslinking within 3D printed samples. Results from this study can be used as a reference for developing new biomass–fungi mixtures for 3D printing in the future.
Silicon carbide (SiC) has found a variety of engineering applications due to its superior properties. However, it is still desirable to study cost-effective processes to machine silicon carbide. This paper presents the results of a designed experimental investigation into Rotary Ultrasonic Machining (RUM) of silicon carbide. A four-variable two-level full factorial design was employed to reveal main effects as well as interaction effects of four process variables (spindle speed, feedrate, ultrasonic power and grit size). The process outputs studied include cutting force, surface roughness and chipping size.
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