How to screen corrosion inhibitors from various cleaning agents for copper, aluminum and steel?
March 06, 2023
Corrosion Inhibitor is a chemical substance or a mixture of several chemical substances that can prevent or slow down corrosion when it exists in the environment (medium) in proper concentration and form. Generally speaking, corrosion inhibitor refers to those substances used to protect metal surfaces. Adding a small amount of such chemicals can significantly reduce the corrosion rate of metal materials in this medium.
Selection of corrosion inhibitor in various cleaning agents Cleaning agent for copper parts and copper alloys Benzotriazole, methylbenzotriazole, 2-mercaptobenzothiazole, and benzimidazole are all corrosion inhibitors for copper materials in cleaning agents for copper parts and copper alloys. Among them, benzotriazole and 2-mercaptobenzothiazole are the most common. It is generally believed that the nitrogen on BTA molecule and the sulfur on MBT molecule form a coordination bond with Cu (I) because they do not share electronic pairs. BTA has the largest adsorption on Cu below 20 ℃, and is most easily adsorbed on 90Cu-10Ni above 25 ℃. The increase of temperature is beneficial to the adsorption of MBT on 70Cu-30. In addition to the above common corrosion inhibitors, some amides, carboxylic acids, phosphate esters, etc. can also be used. The use of corrosion inhibitors should be selected according to different systems. A single corrosion inhibitor is always less effective than a composite corrosion inhibitor. Cleaning agents for active metals such as aluminum, magnesium and zinc and their alloys Active metals in aluminum, magnesium, zinc and other active metals and their alloy cleaning agents often use some gel adsorption substances for corrosion inhibition, such as sodium tripolyphosphate and sodium metasilicate, which are cheap and widely available. In addition, some phosphates and amphoteric imidazolines will be used. Due to the wide application of active metals in the market, corrosion inhibition is difficult. Many manufacturers have introduced a series of composite corrosion inhibitors for this situation. Iron and steel cleaning agent Among iron and steel cleaning agents, iron and steel corrosion inhibitors are commonly used in the market as inorganic corrosion inhibitors, such as nitrite, chromate, thiourea, urotropine, etc. They can also be used in the form of film coating, such as phosphating film, ceramic film, or other coatings. In order to increase the storage time of the base material, some fields use antirust oil for painting, or spray paint for drying, so as to prevent the rust of the base material and achieve the corrosion inhibition effect. In the formulation design of cleaning agent, we first need to determine the corrosion inhibition principle of the corrosion inhibitor according to the properties of the base material and the operating conditions, select the type of corrosion inhibitor according to the corrosion inhibition principle, and select the appropriate corrosion inhibitor according to the environment of the formulation system, then determine the experimental scheme and conduct the corrosion inhibition contrast test for the selected corrosion inhibitor, and screen the corrosion inhibitor with the best corrosion inhibition performance, Finally, the optimum amount of corrosion inhibitor was determined by orthogonal test.
