Table 9: Results of confirmation test.

Initial parameter levelOptimal parameter combination
PredictionExperimentation

LevelA2B2C2D2A3B3C3D3
Ecorr (mV versus SCE)−354.89−278.71
Icorr( 𝜇 A/cm2)0.90310.080
Grade0.6624020.8814170.916275

Improvement of grey relational grade = 0.253873