3DP, whose full name is three-dimensional inkjet printing, is widely used in sand casting to provide sand molds for casting processes, reduce labor costs, and improve product quality. Because the sand molds printed by 3DP have poor strength and mechanical properties, how to improve the performance of 3DP-printed sand molds without increasing their weight has become an urgent problem to be solved. In daily life, composite materials with fibrous substances added have better performance than single materials. Among them, basalt fiber has advantages such as environmental friendliness, low cost, and excellent performance. At present, basalt fiber is widely used in research on enhancing the properties of materials such as concrete and asphalt. It has a significant effect on improving the flexural strength, crack resistance, and frost resistance of concrete. It can also significantly enhance the mechanical properties, high- and low-temperature performance, and water sensitivity of asphalt mixtures.
Basalt fiber was added as a reinforcing phase to 3DP-printed sand molds, their mechanical properties were tested, and the influence laws of basalt fiber addition amount and length on sand mold performance were explored:
1.When the fiber addition amount was between 0% and 0.125%, the strength of the sand mold showed a trend of first increasing and then decreasing with increasing fiber addition amount; when the fiber length was 1–5 mm, the mechanical properties of the sand mold all showed a trend of first increasing and then decreasing.
2.The suitable addition process was as follows: when the fiber addition amount was 0.1%, the tensile strength was 1.963 MPa, which was 85% higher than that of the blank sample; the flexural strength was 5.319 MPa, which was 62% higher than that of the blank sample; when the length was 4 mm, the tensile strength was 2.215 MPa, which was 109% higher than that of the blank sample; the flexural strength was 5.664 MPa, which was 72% higher than that of the blank sample. At the same time, changes in addition amount and length had little effect on the residual strength, and this process met the application requirements.
3.From the microscopic morphology captured by SEM, the well-dispersed fibers played a good role in resisting fracture and enhanced the strength of the sand mold. Some fibers agglomerated, which affected the strength of the sand mold. It can be seen that the dispersion effect of basalt fibers by simple ultrasonic water mixing was not good, so subsequent modification treatment of the fibers can be considered to enhance the dispersion of fibers in water.