Fabrication and Property of Degradable Magnesium-Calcium Alloy Composites with Hydroxyapatite

摘要

Magnesium-calcium alloy and magnesium-calcium alloy base composite are considered as a degradable implant material. Magnesium-calcium base composite, which is made of magnesium-calcium alloy chip and hydroxyapatite powder (HAP), is fabricated with powder metallurgy process that employ the mixing of chip and powder with ball milling and the consolidation of the mixture with hot press and extrusion. Calcium content of the magnesium-calcium alloys is changed from 0.5wt% to 2.0wt%. HAP content of the composites is chosen 8wt% and 16wt%. The magnesium-calcium alloys and the composites are examined mechanical property with tensile test at room temperature. Influence of the calcium content up to 2.0wt% on the mechanical property of the magnesium-calcium alloys and the composites is little. The UTS, proof stress and strain of the magnesium-2.0wt% calcium alloy are 316MPa, 50MPa and 0.11. While the UTS, proof stress and strain of the composite with 8wt% HAP contained 2.0% calcium is 303M Pa, 198MPa and 0.1. The mechanical property of the composite with 16wt% HAP is smaller due to many pores in the microstructure. The corrosion property of the magnesium-calcium alloys and the composites are examined in normal saline solution at 309K (36 degree Celsius). Influence of calcium content on the corrosion property of the magnesium-calcium alloy and the composites is a little. The corrosion rate of the magnesium-2.0wt% calcium alloy is O.OOlg/day. The corrosion rate of the composites with 8wt% HAP and 16t% HAP contained 2.0wt% calcium are 0.0015g/day and 0.0012g/days respectively. The corrosion rates of the composites are higher than the magnesium-calcium alloys. The corrosion rate of the composite with 8wt% HAP is higher than the composite with 16wt% HAP.