The amount of salt spray settlement and spray method in the salt spray test must be clarified. It is necessary to understand the equipment first! The salt spray test is an artificial accelerated corrosion test that simulates the effects of the ocean atmosphere on products. The salt spray corrosion test chamber is an environmental test equipment that artificially simulates this corrosion effect. It mainly assesses the ability of organic coatings, rust-proof greases, metal materials, components, and fully equipped equipment to adapt to the marine atmosphere. Among them, the salt spray settlement parameter of the salt spray test box and the spray method Dongguan OTS chose to explain to you.
First, salt spray test settlement of salt spray and spray mist settlement.
Salt fog settlement reflects salt fog characteristics and is an important parameter in the salt spray test. The past salt spray test method specified the size of the mist particles - between 1 and 5μm in diameter. However, due to the vast majority of experimental equipment, the diameter of the mist particles is within this range, and it is troublesome to measure the diameter of the mist particles. Therefore, many salt spray test methods do not stipulate the size of the mist particles, but instead govern the settlement of the fog. That is, a 10 cm diameter funnel (the area of the funnel is about 80 cm2) is inserted into a 50 ml graduated cylinder, fixed with a rubber stopper, and continuously sprayed for several hours (most of the provisions of the 16h collection liquid), the resulting collection The liquid is converted into settlement, and the unit is ml/80cm2·h. Most are specified as 1~2ml/80cm2·h. When the sedimentation amount is less than 0.5 ml/80 cm2·h, the salt film on the surface of the metal is thin, and oxygen will quickly pass through the water film to reach the cathode surface, so the corrosion rate suddenly increases. With the increase of settlement, there is a medium-thickness liquid film layer on the surface of the metal, and the corrosion rate increases slowly. When the settlement amount continues to increase and exceeds 2 ml/80 cm2·h, the salt film layer on the metal surface becomes thicker, the oxygen diffusion distance increases, and it is difficult to reach the cathode surface, so the corrosion rate is not significantly accelerated. Therefore, taking a moderate amount of settlement will make the corrosion rate more stable and the test results reproducible.
Second, the salt spray test salt spray settlement and spray method.
Salt spray test generally use continuous spray and intermittent spray . Intermittent spray can make the metal surface have periodic alternating wetting and drying, so that the liquid film on the metal surface is updated, so that oxygen is continuously replenished, which is favorable for accelerated corrosion, but also close to the actual work and storage conditions. Continuous spraying can keep the metal surface moist and have a sufficient salt film thickness. The continuous spray test conditions are relatively stable and easy to control. Therefore, many current salt spray test methods use continuous spray.