Biomedical Engineering Reference
In-Depth Information
The results obtained by Taher and Al Jabab (Table 5.12) indicates
that Jelstar and Pontallor-4 alloys acts as the cathode in the coupling
with Ti, which means that the Ti is anode and undergoes corrosion.
For other materials, the Ti acts as the cathode [50]. The galvanic
current measured between anode and cathode materials represents
the ability to corrosion of the anode contacting with the cathode.
The couples which generate the lowest current density value
(Table 5.12) states the best materials for the implant joint. From the
all investigated by them alloys, the Pontallor-4 (Au alloy) states an
excellent couple with the Ti implant, whereas Jelstar (Pd-Ag alloy)
shows acceptable corrosion behavior with Ti contact [50]. R800
and R2000 have acceptable galvanic corrosion with Ti contact. The
RCS and SSTi shows unstable corrosion behavior, whereas Amalgam
shows highest galvanic corrosion, when is coupled with Ti [50].
Table 5.12
The mean values of mixed potential, galvanic current density
and integrated current density during the last 6 h for all
Ti/alloy couples [50]
Current
integration
during the last
6 h (μA/cm
2
)
Galvanic
current
(μA/cm
2
)
Mixed potential
(mV/SCE)
Couple
Count
Ti/Jelstar
3
66.8
0.00
34.4
Ti/Pontallor-4 3
1.7
0.00
-86.2
Ti/R2000
3
-107.1
-0.02
-95.5
Ti/R800
3
-27.4
-0.01
-205.4
Ti/RCS
3
-31
-0.02
-350.3
Ti/Ter Ti
3
-21.1
-0.01
-170.5
Ti/SSTi
3
-184.6
-0.04
-873.5
Ti/amalgam 3
-109.9
-0.08
-1127
To improve corrosion resistance of the stainless steel, the
bioactive glass (CaO-SiO
2
-P
2
O
5
) coating was successfully applied
on the 316L substrate by sol-gel technique [5]. The size of the
used bioactive glass powder was less than 100 nm [5], and inally
deposited layer with 10-20 μm thickness is shown in Fig. 5.33. The
coating strictly adheres to the surface. The corrosion parameters of
the 316L steel, with and without coating are shown in Tables 5.13
and 5.14 in normal saline solution and Ringer's solution, respectively
[5]. Bioactive glass coating improve the corrosion resistance of the
