Tungstate Steel Composite Corrosion Inhibitor

With the shortage of freshwater resources, the environment-friendly water-saving technology using seawater as circulating cooling water has a wide application demand in high water-consuming industries such as electric power and chemical industry. However, the salt content of seawater is high and its composition is complex, which is more corrosive than that of fresh water. Therefore, the biggest technical difficulty in using seawater as circulating cooling water is to solve the corrosion problem of seawater.

tungstate steel composite corrosion inhibitor image

The main methods to solve the problem of seawater corrosion are coating, cathodic protection and adding corrosion inhibitor. There are some defects in coating and cathodic protection, so adding corrosion inhibitor is the most effective way to solve the problem of seawater corrosion.

Tungstate is an environmentally friendly corrosion inhibitor with low toxicity. It can not only change the activation polarization of metals as a corrosion inhibitor for uniform corrosion of metals, but also inhibit pitting corrosion of metals. However, when tungstate is used alone, the corrosion inhibition rate is not high and the dosage is large, while the corrosion inhibition efficiency of tungstate-based composite inhibitors is relatively good. Therefore, it is of great value to study new tungstate composite corrosion inhibitors.

Tungstate steel composite corrosion inhibitor for natural seawater consists of the following components: calcium gluconate 20mg/L, zinc sulfate 40mg/L, sodium polyphosphate 40mg/L, sodium silicate 20mg/L, sodium tungstate 20mg/L (embodiment 1), 40mg/L (embodiment 2), 60mg/L (embodiment 3), 80mg/L (embodiment 4), 100mg/L (embodiment 5), respectively. The above components were mixed and stirred for 20 minutes, then dissolved in 1L seawater. Carbon steel was immersed in seawater with compound corrosion inhibitor at 25 ℃ for 15 days.

After immersion, the corrosion inhibition efficiency was calculated according to the national standard. When sodium molybdate was added at 80 mg/L, the corrosion inhibition effect was the best, and the corrosion inhibition efficiency reached 68.3%. It can be seen from this that the composite corrosion inhibitor of salted carbon steel has high corrosion inhibition efficiency, low cost and environmental friendliness. It has good corrosion inhibition effect at room temperature and high temperature, as well as in ordinary seawater and concentrated seawater twice or three times. It can not only form a protective coating on the surface of carbon steel, but also prevent further corrosion of carbon steel. It can also fill voids and repair defects in the oxide film, and inhibit pitting corrosion of metals.