LASER PROCESSING OF ORTHOPEDIC BIOMATERIALS - Advanced Biomaterials: Fundamentals, Processing, and Applications - page 298

(a)

Bone Cell Proliferation

7

Day 3
Day 6

6

5

4

3

2

1

0

TNZT Ti-6Al-4V

Samples

(b)

Bone Differentiation

20
18
16
14
12
10

Day 3
Day 6

8

6

4

2

0

TNZT Ti-6Al-4V

Samples

Figure 9.18. (a) Bone cell proliferation and (b) Bone cell differentiation results from the sec-
ond test. [Sonia Samuel, (M.S. Thesis, Dept of Mater. Sci. and Eng., University of North Texas,
2007)]

9.3.4 Laser Processed Titanium Boride Reinforced Ti-Nb-Zr-Ta
Metal-matrix Composites
9.3.4.1 Wear Resistance of Titanium Alloys and Titanium Matrix
Composites. As discussed previously, titanium alloys, including beta alloys, typi-
cally exhibit rather poor wear resistance, consequently limiting their application
in the femoral head. Frictional behavior of some selected orthopedic biomaterials
has been studied by Rack and Long [38,39]. The four titanium alloys they studied
were Ti - 35Nb - 8Zr - 5Ta with slightly different compositions (TNZT and TNZTO),
a metastable

- Ti alloy (21SRX) and Ti - 6Al - 4V ELI (Extra Low Interstitial). The
steady state dynamic coeffi cient of friction values in sliding contacts for the meta-
stable

β

-Ti alloys were always higher than that of the Ti-6Al-4V alloy under all
conditions of contact stresses tested. Post-wear testing the surfaces exhibited

β