Mechanical Properties and Bio-Compatibility of Ti-Nb-Zr-HA Biomaterial Fabricated by Rapid Sintering Using HEMM Powders

Abstract

Ti-6Al-4V ELI (Extra Low Interstitial) alloy has been widely used as an alternative to bone due to its excellent biocompatibility. However, it still has many problems, including a high elastic modulus and toxicity. Therefore, nontoxic biomaterials with a low elastic modulus should be developed. However, the fabrication of a uniform coating is challenging. Moreover, the coating layer on Ti and Ti alloy substrates can be peeled off after implantation. To overcome these problems, it is necessary to produce bulk Ti and Ti alloy with hydroxyapatite (HA) composites. In this study, Ti, Nb, and Zr powders, which are biocompatible elements, were milled in a mixing machine (24h) and by planetary mechanical ball milling (1h, 4h, and 6h), respectively. Ti-35%Nb-7%Zr and Ti-35%Nb-7%Zr-10%HA composites were fabricated by spark plasma sintering (SPS) at 1000 o C under 70MPa using mixed and milled powders. The effects of HA addition and milling time on the biocompatibility and physical and mechanical properties of the Ti-35%Nb-7%Zr-(10%HA) alloys have been investigated. Ti 2 O, CaO, CaTiO 3 , and Ti x P y phases were formed by chemical reaction during sintering. Vickers hardness of the sintered composites increases with increased milling time and by the addition of HA. The biocompatibilty of the HA added Ti-Nb-Zr alloys was improved, but the sintering ability was decreased.Key words biomaterial, hydroxyapatite, powder metallurgy, SPS, sintering. 서 론Ti

Microstructure and Mechanical Properties of Nano-Carbon Reinforced Titanium Matrix/Hydroxyapatite Biocomposites Prepared by Spark Plasma Sintering

“…Figure 3 and Table 2 show the microscopic morphology and composition of composite powders after ball milling. It can be found from Figure 3 that the particle size of milled powders is about 5 μm–30 μm compared with the average particle size (about 45 μm) of original powders, which is caused by the continuous cold welding-grinding process during ball milling [ 36 ]. However, research also revealed that refined particles will reunite when the ball milling time is too long [ 12 ].…”

Research Progress Regarding Interfacial Characteristics and the Strengthening Mechanisms of Titanium Alloy/Hydroxyapatite Composites

“…Compared with coating, there are similar complex chemical reactions in uncoated composite. Researchers revealed that some new phases, such as Ca 5 (PO 4 ) 3 (OH), CaTiO 3 , Ti x P y , β-Ti, Ti 2 O, CaO, Ca 4 O(PO 4 ) 2 , Ca 3 (PO 4 ) 2 (TCP), CaTi 4 (PO 4 ) 6 , etc., have appeared in Titanium alloys/HA composites prepared by powder metallurgy and other methods [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ]. The presence of calcium titanate produced by the reaction between Titanium and HA showed the existence of interfacial chemical reactions [ 27 ].…”

“…Particle shape was also changed from needle-like or disk-like to spherical. Thus, the hardness and corrosion resistance of composites increased with the improvement of milling time due to the grain refinement strengthening effect [ 24 ]. However, the refined particles continued to agglomerate, and the mechanical properties reduced if the ball milling time was too long [ 32 ].…”

“…It has been found that after adding HA, the hardness of Titanium alloy/HA composites increases, while the sintering capacity decreases [ 24 ]. This was because HA has higher hardness value and biological activity, but higher porosity in the reactions led to a decrease in sintering capacity [ 24 ].…”

“…However, there are some problems such as stress shielding phenomenon, complex reactions, and so on [ 1 , 4 , 5 , 6 ]. Research showed that there were some new phases such as Ca 5 (PO 4 ) 3 (OH), CaTiO 3 , Ti x P y , β-Ti, Ti 2 O, CaO, Ca 4 O(PO 4 ) 2 , Ca 3 (PO 4 ) 2 (TCP), and CaTi 4 (PO 4 ) 6 in Ti alloy/HA composites after high temperature sintering [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ]. It reveals that there are complex reactions between Ti and HA when sintered at a high temperature.…”