Iron–Paraffin Composite Material for 3D Printing by Fused Deposition Modeling Method

Abstract

Fe-powder and paraffin-based or similar systems are widely used for low-temperature injection molding. The main attention of research efforts on such compositions is focused on the study of their rheology. At the same time, such materials can be adapted for 3D printing by layer-by-layer surfacing, requiring only necessary rods or filaments with a sufficient level of mechanical properties so as not to break during printing. Hence, this paper examines the influence of paraffin content on the compressive strength of samples made of carbonyl iron powder and paraffin in the ratio: 50/50, 60/40, 70/30, and 80/20 vol.%. Computer calculations of critical deformation, elasticity modulus, and compressive strength of such composites have been performed. According to the examination and calculation results, the modulus of elasticity varies from 1358 to 113 MPa with a higher paraffin content, the critical deformation ranges between 0.257 and 3.310, and the compressive strength is between 0.339 and 0.761 MPa. Iron powder was mixed with paraffin in a planetary mill for 3 min with a subsequent sieving of the mixture. Afterward, pressed cylindrical samples with a volume of ~1 cm3 and a height of ~10 mm were used to determine the density and compressive strength. It was found that the density of the samples after pressing is 1.3 times lower than the calculated by the additivity formula at a binder content of 20 vol.%. Only when the binder content increases to 50 vol.%, the actual density approaches the calculated values, that is, the relative porosity varies from 0.212 to 0. With an increase in paraffin content from 20 to 50 vol.% the strength of the samples increases along the concave curve from 3 to 11 MPa. The dependences of the calculated and experimentally obtained compressive strength are similar, indicating the adequacy of the established models. However, significant variation in values is due to the difference between the properties of paraffin under study and that used for testing. Samples of rods with 40 and 60 vol.% Fe was extruded and tested by 3D printing. The obtained experimental data can be used in the creation of other similar working materials for 3D printing in the layer-by-layer surfacing.