2.3.2. Extrudability Extrudability is one of the critical parameters for 3D printing, and shows whether the materials can be extruded as a continuous and homogenous filament through the nozzles without any disruption. The extrudability of LG mixtures was performed by means of a high-pressure syringe pump (Fusion 6000, Chemyx, Inc.) with a constant pump rate of 25 ml/min at room temperature (RT) and in a vacuum thermal chamber at 80 C. In addition, to quantify the early age properties of the mixtures such as workability, consistency, and flow behavior, rheological characterization is required [26]. Yield stress and viscosity of the material can be considered as flow properties inside any pipe or complex shaped channel [27]. Therefore, rotational rheological measurements of fresh LG0, LG3, and LG5 were carried out using an Anton Paar MCR302 rheometer (Austria) at 80 C. The mixtures were tested using a PP25/P2 (parallel plate) plateeplate measuring system (diameter: 25 mm; inset I-PP50/SS) After loading the pre-heated mixture into the 80 C rheometer plate, the sample was kept in the rheometer at 80 C for 60 s, to ensure that the samples have the same temperature history. The samples were measured from 104 to 100 s1 using a logarithmic ramp with 1 s per data point and 61 data points. Yield stress values were estimated utilizing the Bingham model: t ¼ t0 þ mpg_ , where t is the shear stress, t0 is the yield stress, mp is the plastic viscosity, and g_ is the shear rate [28]. The data were fitted in the low shear rate range (g_ <0:01 s1) where the curves are linear.
2.3.3. Buildability The buildability of fresh LG mixtures was examined by means of a high-pressure syringe pump (Fusion 6000, Chemyx, Inc.) with a constant pump rate of 25 ml/min.
Read the full article here: Investigation of severe lunar environmental conditions on the physical and mechanical properties of lunar regolith geopolymers
Date Published: January 29, 2021
Authors: Shima Pilehvar, Marlies Arnhof, Andreas Erichsen, Luca Valentini, AnnaeLena Kjøniksen
