The most direct method to evaluate the corrosion resistance of the coating film is the physical experiment. Under the actual use conditions, observe the corrosion of the coating on the substrate to judge the corrosion resistance of the coating. This method truly reflects the corrosion resistance of the coating in the environment. state in the medium. However, this method is time-consuming and expensive. At present, more simulation accelerated testing methods are adopted in the laboratory, mainly including salt spray test, corrosive gas test, electrolytic accelerated corrosion test, damp heat test, etc., so as to obtain the tendency of metal corrosion in a short period of time. However, in view of Due to the complexity of corrosive media and environmental conditions, only relatively limited results can be obtained.
The neutral salt spray test is one of the commonly used artificial accelerated corrosion tests. The salt spray in the marine atmosphere is composed of dispersed tiny droplets and chlorides. Chloride ions are highly penetrating and corrosive. At present, my country adopts the national standard GB/T 1771-2007 "Paints and Varnishes-Determination of Neutral Salt Spray Resistance". Evenly settle on the surface of the test sample. The test conditions are: the test solution is a 5% NaCl solution by mass fraction, the Test Chamber temperature is 35±2°C, the pressure barrel temperature is 47±2°C, the pH value is 6.5-7.2, the spray volume is 1-2ml/80cm2/h, continuous spray . The angle between the test surface and the vertical direction is 20°±5°. The scratch test method is adopted. The scratches are perpendicular to each other: the length is 80mm, and the width is 0.5mm. distance.
