Characterization of tensile and hardness properties and microstructure of 3D printed bronze metal clay

Abstract

Bronze is a popular metal for many important uses. Currently, there are no economical 3D printers that can print Bronze powders. A recent product, Bronze Metal Clay (BMC) has arrived. Additionally, commercial metal 3D printers require laser or electron beam sources, which are expensive and not easily accessible. The objective of this research is to develop a new two-step processing technique to produce 3D printed metallic component. The processing step includes room temperature 3D printing followed by high-temperature sintering. Since no material data exists for this clay, the tensile strength and hardness properties of BMC are compared to wrought counterpart. In this research tests are completed to determine the mechanical properties of Cu89Sn11 Bronze Metal Clay. The author of this thesis compares the physical properties of the same material in two different formats: 3D printed clay and molded clay. Using measured stress-strain curves and derived mechanical properties, including Young's modulus, yield strength, and ultimate tensile strength, the two formats demonstrate inherit differences. The Ultimate tensile strength for molded BMC and 3D-printed specimens sintered at 960 C was 161.94 MPa and 157 MPa, respectively. A 3D printed specimen which was red at 843 C had 104.32 MPa tensile strength. Factory acquired C90700 specimen had an ultimate stress of 209.29 MPa. The Young's modulus for molded BMC and 3D-printed specimens sintered at 960 C was 36.41 GPa and 37.05 GPa, respectively. The 843 C 3D-printed specimen had a modulus of 22.12 GPa. C90700 had the highest modulus of 76.81 GPa. The Yield stress values for molded BMC and 3D-printed specimens sintered at 960 C was 77.81 MPa and 72.82 MPa, respectively. The 3D-printed specimen had 46.44 MPa. C90700 specimen had 115.21 MPa. Hand molded specimens had a Rockwell hardness HRB85, while printed samples had a mean of HRB69. Also, molded samples recorded a higher Young's Modulus of 43 GPa vs. 33 GPa for the printed specimens. Both samples were weaker than the wrought Cu88:8Sn11P0:2 which had a 72 GPa. Cu88:8Sn11P0:2 also was a harder material with an HRC45. The property di erence between 3D printed, molded, and wrought samples was explained by examining their micro structures. It shows that 3D printed sample had more pores than the molded one due to printing process. This study demonstrates the flexibility and feasibility of using 3D printing to produce metallic components, without laser or electron beam source.