Fabrication of three-layer graded magnesium foam by means powder metallurgy and spacer method with an application in bioimplants: macro morphology, microstructure and compressive properties evaluation

In this paper a three-layer graded magnesium foam with a potential application in bone implants is produced by means of powder metallurgy and spacer method. The gradation is based on the density variation between the layers. In order to so, three different combinations of magnesium powder and carbamide particles (used as the spacer) are considered in three layers and the graded structure is compacted under a pressure of 300 MPa and finally sintered at 400°C for 4 hours. SEM analysis and compression tests are conducted on the produced specimens to determine the microstructure and mechanical properties of the graded foam, respectively. The results show that increasing the percentage of the carbamide spacer can lead to producing open cell foam. This means that this kind of foam can be used for repairing bone tissue scaffolds. In addition, while the mechanical properties of bulk magnesium implants are far from that of a compacted human bone, the produced three-layer graded foam can resemble spongy bone structures properties excellently. Furthermore, similar mechanical properties to human spongy bone can be obtained by gradation of the foam rather than applying single layer foams. This means that potentially, the three-layer graded magnesium foam may be utilized in human bone implants.