All the test specimens of LNSS were cut into an overall apparent size of 1 x 1 x 0.3 cm and embedded using epoxy resin with an electrical connection and exposed area of 1 [cm.sup.2].
A platinum electrode and a saturated calomel electrode (SCE) were used as auxiliary and reference electrodes, respectively, while the working electrode was composed of LNSS of 1 [cm.sup.2] exposed area.
The SEM image of poly(TBPMA-co-GMA) and poly(PBPMA-co-GMA) film developed on austenitic LNSS is presented in Figs.
The cathodic and anodic polarization curves of LNSS in 1 M [H.sub.2]S[O.sub.4] without and with coating of copolymers are shown in Figs.
The corrosion rate calculated for LNSS specimens coated with copolymers are also shown in Table 5.
8a the [C.sub.dl] represents the double layer capacitance, and [R.sub.1] represents a resistance of the coating which is a passive film in the case of coated austenitic LNSS. The second subsystem corresponds to the resistance ([R.sub.2]) and the capacitance to the charge transfer of the oxidation of the alloy.
In the case of uncoated LNSS in 1 M [H.sub.2]S[O.sub.4] environment, the equivalent circuit, such as that shown in Fig.
Figure 9 shows the impedance spectra of the uncoated and copolymer-coated LNSS specimens recorded at OCP in the frequency range of 100 kHz-1 Hz; the amplitude was 10 mV.
The [R.sub.ct] value calculated for uncoated LNSS was 61.2 [OMEGA] and [C.sub.dl] was 0.442 [mu]F [cm.sup.-2].
The possible mechanism involving the effectiveness of the copolymer on LNSS depends on the polymeric structure.