*Article* **Synthesis of Spinel-Hydroxyapatite Composite Utilizing Bovine Bone and Beverage Can**

**Agus Pramono 1,\*, Gerald Ensang Timuda 2,\*, Ganang Pramudya Ahmad Rifai <sup>1</sup> and Deni Shidqi Khaerudini 2,\***


**Abstract:** Spinel-based hydroxyapatite composite (SHC) has been synthesized utilizing bovine bones as the source of the hydroxyapatite (HAp) and beverage cans as the aluminum (Al) source. The bovine bones were defatted and calcined in the air atmosphere to transform them into hydroxyapatite. The beverage cans were cut and milled to obtain fine Al powder and then sieved to obtain three different particle mesh size fractions: +100#, −140# + 170#, and −170#, or Al particle size of >150, 90–150, and <90 μm, respectively. The SHC was synthesized using the self-propagating intermediate-temperature synthesis (SIS) method at 900 ◦C for 2 h with (HAp:Al:Mg) ratio of (87:10:3 wt.%) and various compaction pressure of 100, 171, and 200 MPa. It was found that the mechanical properties of the SHC are influenced by the Al particle size and the compaction pressure. Smaller particle size produces the tendency of increasing the hardness and reducing the porosity of the composite. Meanwhile, increasing compaction pressure produces a reduction of the SHC porosity. The increase in the hardness is also observed by increasing the compaction pressure except for the smallest Al particle size (<90 μm), where the hardness instead becomes smaller.

**Keywords:** hydroxyapatite composite; spinel; beverage cans; bovine bones
