With the continuous development of industry, the use of steel is also increasing. However, during the production process or finished product storage process, steel sheets are prone to oxidation and rust when encountering humid air and rainy days, which affects the appearance quality of products. This has brought problems to the use of steel, and the annual loss of steel caused by corrosion is astonishing.
According to statistics, the annual loss of steel due to corrosion worldwide is equivalent to 30% of annual production. Not only that, the equipment will also be damaged due to corrosion, causing shutdown and production, resulting in a decrease in product quality and causing huge losses to social wealth. Rust is a major enemy of steel, so how to protect steel, prevent its rusting and deterioration, and increase its service life has become a common topic of concern. Metals are divided into non-ferrous metals and Ferrous, and Ferrous include iron, manganese and chromium. Iron is hard and ductile, has strong ferromagnetism, good plasticity and thermal conductivity, and is widely distributed on Earth. Various alloys based on iron, including cast iron, carbon steel, stainless steel, etc., are widely used.
Ferrous water-based antirust agent is a water-based antirust solution, which can effectively protect steel, iron and other materials from rust.
1. Ferrous water-based rust inhibitor
The water-based antirust agent for Ferrous generally consists of Corrosion Inhibitor, complexing agent, alkali, wetting agent, etc. The substance that plays a core role in the rust prevention process is corrosion inhibitor, and different corrosion inhibitors have different corrosion inhibition mechanisms. Different combinations of corrosion inhibitors result in significant differences in rust prevention performance. Common inorganic corrosion inhibitors include Sodium nitrite, Sodium molybdate, Sodium tungstate, boric acid, borax, phosphate, etc. They are all anodic oxidation inhibitors. There are more kinds of organic corrosion inhibitors, such as well-known carboxylic acid salts: monocarboxylic acid, dicarboxylic acid, ternary acid, etc. In addition, fatty acid amides, borate esters, petroleum sulfonates, alkyl succinic acid, cationic Quaternary ammonium cation salts, etc. This type of corrosion inhibitor contains elements with lone pair electrons such as nitrogen, phosphorus, sulfur, and oxygen, and can directly form a chemical adsorption layer on the metal surface. It belongs to the mixed type of corrosion inhibitor.
Common complexing agents include EDTA, phosphate, etc. The amount and type of complexing agent added have a significant impact on rust prevention performance. The chelating agent chelates with calcium and magnesium ions in water, while the corrosion inhibitor reacts with free sodium and potassium ions to form sodium or potassium salts. Monovalent sodium and potassium salts themselves foam, and their adsorption performance is not as good as that of divalent salts. The decrease in adsorption performance weakens the rust prevention performance. Only a few complexing agents can enhance rust resistance. Wetting agents play a role in reducing surface tension and improving the wetting performance of rust inhibitors. Most corrosion inhibitors themselves have certain surface activity, so it is generally not necessary to add additional wetting agents. 2. Instrumental chemistry method The analysis of Ferrous rust inhibitor plays an important role in the research and development of rust inhibitor.
Infrared spectroscopy IR
Infrared spectroscopy is widely used for qualitative analysis of small molecules and polymer compounds, which is a relatively simple and fast analysis method. Figure 1 is the infrared matching spectrum of an unknown substance. Through the matching spectrum, we can know that the unknown substance is Triethanolamine oleate soap, which belongs to monobasic Carboxylate.
Fig. 1 Infrared spectrum of Triethanolamine oleate soap
Nuclear magnetic resonance instrument NMR
Nuclear magnetic resonance can analyze and test corrosion inhibitors in rust inhibitors. Figure 2 shows the 1H-NMR spectrum of a corrosion inhibitor.
Figure 2 NMR spectrum of benzotriazole
Gas chromatography-mass spectrometry coupled with GC-MS
The gas chromatography-mass spectrometer can be used to analyze the volatile solvent in the antirust agent sample. Figure 3 is the GC-MS spectrum of chloroform extract of a water-based inhibitor, Figure 4 is the 14.88min outflow mass spectrum in the spectrum, and Figure 5 is the 14.88min outflow matching spectrum in the spectrum. Through the matching spectrum, it can be inferred that the water-based antirust agent sample contains Triethanolamine borate.
Figure 3 GC-MS spectrum of a mixture
Figure 4 Mass Spectrogram of 14.88min Effluent Substance in GC-MS Spectrogram
Figure 5 Matching map of 14.88min outflow substance in GC-MS map (Triethanolamine borate)
Liquid chromatography-mass spectrometry combined with LC-MS
Liquid chromatography-mass spectrometry is used to characterize polar compounds in rust inhibitors, including organic corrosion inhibitors, inorganic corrosion inhibitors, complexing agents, etc. Figure 6 is the MS spectrum of a water-based rust inhibitor. Through this MS spectrum, it can be seen that there is information about ternary polycarboxylic acids in the rust inhibitor.
Figure 6 ESI spectrum of a water-based rust inhibitor
Liquid phase ion chromatography IC
Liquid phase ion chromatography can analyze inorganic ions in water-based corrosion inhibitor. Figure 7 is the IC spectrum of a water-based corrosion inhibitor. It can be seen from the figure that Sodium nitrite is included in the rust inhibitor.
Figure 7 IC spectrum of a water-based rust inhibitor
With the increasing demand for rust prevention and environmental protection in industries such as machining, the rust prevention performance of water-based rust inhibitors has also been improved. The key component is the type and combination of corrosion inhibitors. There are many kinds of corrosion inhibitors. It is difficult to analyze accurately with a single instrument, but it is still necessary to conduct Conjoint analysis with multiple equipment to obtain an accurate analysis data.
Conjoint analysis with a variety of instruments can effectively carry out qualitative and quantitative analysis of metal antirust agents, and can also make targeted analysis and personalized design plans for the substances or functions concerned by customers, helping enterprises in product research and development, product production, product pre research and other work.
