Improvement of the Corrosion Resistance of Aluminium Alloys Applying Diff erent Types of Silanes - Advanced Materials for Agriculture, Food and Environmental Safety - page 32

2.2.1 Classii cation of Silanes

In general there are two possible ways to classify silanes:

a. According to their structure: mono-silane (Figure 2.1)
(mono-silyl functional silanes) (see examples in Table 2.1)
and bis-silane (Figure 2.2) (bis-silyl functional silanes) (see
examples in Table 2.2). h e mono-silanes have the general
structure R 3 Si(CH 2 ) n R ' , where R represents a silicon ester, R '
is an organofunctional group such as chlorine, primary or
secondary amines, or vinyl, and the value of n is around 3.
Bis-silanes (dipodal silanes) (Figure 2.2) with the struc-
ture R 3 Si(CH 2 ) n Y(CH 2 ) n SiR 3 with Y- as a functional group,
or without a functional group R 3 Si(CH 2 ) m SiR 3 , generally
assure better corrosion protection for dif erent metals
and alloys such as Al, Zn, Cu, Mg and steel [20-22,29]

OR

R

Si

OR

OR

Figure 2.1 General chemical structure of mono-silane.

Table 2.1 Formula and chemical structure of typical monofunctional silanes.

Name of silane Formula Chemical structure

Vinyltriacetoxy
silane (VTAS)

CH 2 =CH(CH) 3 Si(COCOCH 3 ) 3

H 3 C

O

O

CH 3

H 2 C

Si O

O O

O

H 3 C

Vinyltriethoxy
silane (VS)

CH 2 =CHSi(OC 2 H 5 ) 3

CH 2

H 3 C O

Si

O

O

CH 3

H 3 C

γ-aminopropyl
triethoxysilane
(γ-APS)

(H 5 C 2 O) 3 Si-(CH 2 ) 3 -NH 2

H 3 C
H 3 C

O

NH 2

Si

O

O

CH 3