Treatment of test pieces before electroplating of electric heating tubes

Treatment of test pieces before electroplating of electric heating tubes

1. Machine oil and rust removal

Afterwards, using a grinder to smooth out the six surfaces can not only remove rust but also make the appearance of the specimen flat, which is not conducive to the comparison and appreciation of the specimen plating.

2. Chemical degreasing

Chemical oil removal refers to the saponification infection and appearance activity of Duba alkali solution, which emulsifies non saponifiable oils and removes various oil stains on the appearance of the test piece. The temperature range for chemical degreasing is generally between 60 and 80 ℃. The degreasing effect of the test piece is generally visual inspection, which means that the appearance of the test piece can be completely wetted by water, indicating the complete removal of oil stains. A general degreasing solution is formed by sodium hydroxide, sodium carbonate, sodium phosphate, water glass, emulsifiers, etc.

Sodium silicate can emulsify and meta-infect to aid in straightening and degreasing, but the specimen must be thoroughly cleaned after degreasing. Otherwise, after acid washing, the residual sodium silicate will react with acid to form insoluble silica gel, causing spots on the coating and affecting its clustering strength. Therefore, a surface active agent with uniform infection but no side infection to the plating solution is selected to replace sodium silicate. Appearance active agents should be alkali resistant, that is, those that can exist strongly in alkaline solutions. Non ionic and anionic types or their clusters can be selected. The appearance active agents applicable in alkaline solutions include detergents 650-, 6503-, 664-, and sodium dodecylbenzenesulfonate.

Assuming that the oil removal is incomplete once, it should be rinsed with water and then immersed in the oil removal solution. This should be repeated until the oil is completely removed. The standard for oil removal is that the appearance of the substrate reaches a complete wetting form, can form an average water film, and has no hanging beads.

3. Acid washing

Pickling solution formula: 1: One hydrochloric acid (volume ratio) Workmanship premise: temperature: room temperature; Time: 5-30 seconds

4. Activation

Activation is the process of enabling the entire machine to lose its fully activated appearance, and this type of acid corrosion is related to the different materials used in the entire machine. The activation of general steel parts can be stopped with 10% sulfuric acid or 1: 1 hydrochloric acid, and the activation standard is to stop activation when light and average bubbles appear on the surface of the test piece.

Activation solution formula: -0% sulfuric acid (volume ratio): ρ= 1、 84g/cm3 working condition: room temperature; Time: 0-20 seconds.