MATERIALS FOR ORTHOPEDIC APPLICATIONS - Advanced Biomaterials: Fundamentals, Processing, and Applications - page 71

(a) (b)

Figure 3.10. SEM images of worn surfaces of Ca-FSZ ceramics (MW, 1585 °C) (a) and that
on Ca-PSZ ceramic (b) after testing against steel in SBF. The double pointed arrow indicates
fretting direction. Fretting conditions: 10 5 cycles, 10 Hz frequency, 10 N load and 80 μ m stroke

length. Counterbody: 6 mm diameter steel ball 59 .

In their recent work, González et al. 61 described the method of synthesizing
bio-silicon carbide (SiC) from plants and also proved the biocompatibility of this
new generation of biomaterials by in vitro and in vivo experiments. For their
work, they chose specifi c plant species as templates whose chemical composition
can be changed by some specifi c transformation method while maintaining the
original biostructure. By this method, it is possible to develop lightweight and
high-strength scaffolds for bone substitution. Their in vitro and in vivo experi-
ments demonstrated how the plant species became colonized by the hosting bone
tissue due to its unique interconnected hierarchic porosity.

3.5 POLYMERIC BIOMATERIALS

Polymers are useful in different engineering applications due to their light weight,
low COF ductility and easy formability/moldability. However, polymers lack high
E-modulus, hardness and strength compared to ceramics and metals. Few of the
polymers possess good biocompatible properties that could be exploited in de-
signing several biomaterials. The following overview reviews selected polymers
and their composites that were extensively used and investigated as hard tissue
biomaterials over the last few decades.
Major advantages of polymers are their attractive properties and availability
in a wide variety of composition, and forms (solid, fi bers, fabrics, fi lms and gels).
Polymeric materials can be broadly classifi ed as thermoplastics and thermosets.
For example, HDPE and PEEK are examples of thermoplastics, while SR, PDMS,
PMMA are examples of thermosets 62 . Despite their good biocompatibility, many
of the polymeric materials are mainly used for soft tissue replacement (such as
skin, blood vessel, cartilage, ligament replacement etc).