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What is the working principle of electrolytic cleaning of packaging steel strips?
by：Hongmei
2021-03-15
What is the working principle of electrolytic cleaning of packaging steel strips?
When the steel strip connected to the negative or positive electrode passes through the electrolytic cell, the steel strip becomes the positive or negative electrode of the electrolytic cell. During the electrolysis process, fine hydrogen or oxygen will be generated on the surface of the steel strip. These fine bubbles have the effect of promoting the peeling of dirt from the surface of the steel strip to be cleaned. In electrolytic degreasing, alkaline aqueous solutions such as sodium hydroxide and sodium carbonate are used. The presence of these strong alkaline electrolyte ions increases the conductivity of water and promotes the removal of dirt. Because lye has a strong dispersing effect on lipid and oily dirt. However, the addition of alkaline substances such as sodium hydroxide has a weak ability to disperse mineral oil and other dirt, so sodium metasilicate and a small amount of surfactant should be added to the solution to facilitate the dispersion and removal of mineral oil dirt.
When the color-coated substrate is zinc or aluminum, weak alkali such as sodium silicate is often used as electrolyte due to poor alkali resistance. Sodium metasilicate can significantly improve the alkali corrosion resistance of non-ferrous metals. When aluminum is dewaxed by anode electrolysis (that is, the metal aluminum to be degreased is connected to the positive electrode of the electrolytic cell power supply. During the electrolysis process, the metal aluminum is used as the anode to deposit anhydrous silica gel coating on the aluminum surface of the anode gold region to protect aluminum Call corrosion. When the added surfactant has excessive foaming performance that hinders degreasing, use a low-foaming surfactant or a daily-feeding surfactant dosage.
The method of electrolytic degreasing is classified into cathode degreasing and anode degreasing according to the condition of the degreased substrate as an electrode. Connecting the degreased substrate to the negative electrode of the power supply is called cathode degreasing. In the electrolysis process, the hydrogen produced at the cathode is twice the oxygen produced at the anode, so the hydrogen produced at the cathode has a better effect on the removal of dirt on the surface of the substrate. However, if the treatment is excessive, powdery substances will be formed on the surface of the cleaning object, that is, the steel strip. At this time, a post-acid pickling treatment is required to remove these substances. In addition, when steel is degreasing the cathode electrode, the hydrogen that is also generated will be absorbed and cause embrittlement. This phenomenon is called hydrogen embrittlement. The occurrence of hydrogen embrittlement is most obvious in various high and low carbon steels and metallic zinc. Moreover, brittleness is directly proportional to the amount of hydrogen absorbed. Therefore, steel substrates usually do not use cathode electrolytic degreasing but anode degreasing.
When the steel strip connected to the negative or positive electrode passes through the electrolytic cell, the steel strip becomes the positive or negative electrode of the electrolytic cell. During the electrolysis process, fine hydrogen or oxygen will be generated on the surface of the steel strip. These fine bubbles have the effect of promoting the peeling of dirt from the surface of the steel strip to be cleaned. In electrolytic degreasing, alkaline aqueous solutions such as sodium hydroxide and sodium carbonate are used. The presence of these strong alkaline electrolyte ions increases the conductivity of water and promotes the removal of dirt. Because lye has a strong dispersing effect on lipid and oily dirt. However, the addition of alkaline substances such as sodium hydroxide has a weak ability to disperse mineral oil and other dirt, so sodium metasilicate and a small amount of surfactant should be added to the solution to facilitate the dispersion and removal of mineral oil dirt.
When the color-coated substrate is zinc or aluminum, weak alkali such as sodium silicate is often used as electrolyte due to poor alkali resistance. Sodium metasilicate can significantly improve the alkali corrosion resistance of non-ferrous metals. When aluminum is dewaxed by anode electrolysis (that is, the metal aluminum to be degreased is connected to the positive electrode of the electrolytic cell power supply. During the electrolysis process, the metal aluminum is used as the anode to deposit anhydrous silica gel coating on the aluminum surface of the anode gold region to protect aluminum Call corrosion. When the added surfactant has excessive foaming performance that hinders degreasing, use a low-foaming surfactant or a daily-feeding surfactant dosage.
The method of electrolytic degreasing is classified into cathode degreasing and anode degreasing according to the condition of the degreased substrate as an electrode. Connecting the degreased substrate to the negative electrode of the power supply is called cathode degreasing. In the electrolysis process, the hydrogen produced at the cathode is twice the oxygen produced at the anode, so the hydrogen produced at the cathode has a better effect on the removal of dirt on the surface of the substrate. However, if the treatment is excessive, powdery substances will be formed on the surface of the cleaning object, that is, the steel strip. At this time, a post-acid pickling treatment is required to remove these substances. In addition, when steel is degreasing the cathode electrode, the hydrogen that is also generated will be absorbed and cause embrittlement. This phenomenon is called hydrogen embrittlement. The occurrence of hydrogen embrittlement is most obvious in various high and low carbon steels and metallic zinc. Moreover, brittleness is directly proportional to the amount of hydrogen absorbed. Therefore, steel substrates usually do not use cathode electrolytic degreasing but anode degreasing.
