Stainless steel 304 and 316 are widely used in heat exchangers

and get the precipitation characteristic of CaCO3 is the first step to research anti-fouling technology. CaCO3 precipitated on stainless steel 304 and 316 coupons from 1.0mmol/l CaCO3 solution at 35℃. By weighing the coupon before and after experiment and using scanning electron microscope (SEM)

the amount of fouling and the morphology can be obtained. The results show that at the same conditions there are more fouling on stainless steel 304 than 316; high pH not only makes more new crystal nucleation but also promotes square aragonite and calcite

and recrystallization of square aragonite into calcite

the most thermodynamically steady crystal type; high pH makes both homogeneous and heterogeneous nucleation rate increasing

but the former increases more

which results in more fouling at low pH under high supersaturation degree; fouling first grows at the place with high surface energy and then extend to more place

and when the number increases and crystal grows to connect each other

fouling layer is formed.