Mechanical Properties Of Bone Essay

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Figure 2.3: The structure of bone (Abedon, 2014)

2.1.2 Mechanical Properties

Bones is always considered as man-made engineering materials. Due to its synthesis there have more variation in properties than engineering materials. The factors can include as the location in body, mineral content, disease, age, gender and the amount of water that presence in the human body. The mechanical properties of bone tissues must be considered as very hard and lightweight material. Mechanical behavior of bone can be explained using composite method. Bone tissues are structural and supportive tissues of the body system. It is actually made up of the composite material which is the calcium phosphate in termed of hydroxyapatite that give bone their rigidity
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The calcium phosphate without the magnesium produces higher crystalline and crystal size in composition. While the increase in the magnesium content will make the XRD peaks become significantly broader. This is due to decreased in crystalline size with the increase in the lattice disorder (Hanifi and Fathi, 2010).

Table 2.2: Mechanical Properties of Calcium Phosphate (An Introduction to Tissues Biomaterials Interactions, 2002)

Young Modulus, E(GPa) Compressive Strength (MPa) Tensile Strength
(MPa)
Calcium Phosphate 40 (117) 510 (896) 69 (193)

The major drawbacks to the use of ceramics as implants are depend on the brittleness and poor tensile properties as shown in Table 2.2. The mechanical properties of calcium phosphates make improper used as load-bearing implants. The young modulus for calcium phosphate is 117GPa.While the compressive strength and tensile strength are 896GPa and 193GPa each respectively.
2.3.1 Types of Calcium Phosphate
There are many types of calcium phosphate that has been known. Some of the main types of calcium phosphate are shown in table 2.3.
Table 2.3: Types of Calcium Phosphate (Ben-Nissan et al., Encyclopedic Handbook Biomaterials and Bioengineering, 2004)

Calcium Phosphate Phase
Mineral
Empirical Formula
Ca/P
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According to Boanini, Gazzano and Bigi (2010), based on the research the dicalcium phosphate is produced by the reaction between the calcium chloride and phosphoric acid. Dicalcium phosphates are known as dibasic calcium phosphate or calcium monohydrogen phosphate. It is insoluble in water, but if contact with water, it converts to hydroxypatite. It is known as DCPD by the name brushite and crystallizes in a monoclinic. The DCPC phase is below pH 6.5 easily hydrolyzes to be more stable.
CaCI2 + H3PO4+2NaO CaHPO4+ 2NaCI + 2H2O

Apart from that, the Octacalcium phosphate is more soluble and it is triclinic structure. The pH octacalcium phosphate Ca8H2 (PO4)6.5H2O is more soluble. While, the tricalcium phosphates (TCP) have two different crystalline (Ca3(PO4 )2) known as ambient condition. The hydroxyapatite, HA (Ca10(PO4)6(OH)2) is stable, dense and most insoluble of the CaPs (Boanini et

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