The Research Of Preparation And Property On The Cavitation Resistant Elastic Polymer Coating

Cavitation corrosion is a universal destructive form of hydraulic construction and water conservancy machinery, has seriously hampered the development of hydraulic construction and water conservancy machinery. As a result, a new type of anti-cavitation materials and technology need to be developed urgently. On the outer surface of the flow components, coated with organic elastomer coating which is an effective surface engineering technology to improve the material’s anti-cavitation property. Through adjusting polyurethane elastomer’s hardness, tensile strength, elongation at break, and damping capacity, screening the materials and optimizing the ingredients, polyurethane elastomer with excellent properties can be obtained to be applied to the anti-cavitation protective coating.Based on analyzing the cavitation’s development, bursting theory and exploring the application of this elastomeric coating in the anti-cavitation field, 4 kinds of polyether polyols, 4kinds of isocyanate monomers, 10 kinds of chain extenders were chose to interact at among 65~ 95℃ for 0.5~3.5h. As a result, the polyurethane prepolymer with 7.5% isocyanate group was obtained at 85℃ for 2.5 hours with PTMG1000、the polyol with 3 functional groups and MDI as its materials. This kind of polyurethane prepolymer was used as the A ingredient of the anti-cavitation protective coating.Mixing the A ingredient and chain extender MMC(B ingredient) at different scales and lasting 20 minutes, after it solidifies, the tensile strength of the elastomer was 18.17 MPa, the elongation at break was 410%, and it can keep good elastic properties at indoor temperature to 150℃.The obtained coating has good flexibility, shock strength, salt spray resistance, saline resistance thermal aging property. It has strong adhesion to the metal substrates, which could reach to 10.62 MPa.The mechanical property of the coating keeps unchanged after being soaked in the heated seawater at 40℃ for 90 days. When the coating thickness was 1000μm, the coating of the polyurethane elastomer wasn’t destroyed by cavitation erosion for 120 hours. The mechanical property of the coating were improved after adding a very small amount of Cu2 O, however, the ability to prevent the sea animals was poor.