Q:How does electroplating time affect the quality of electrogalvanizing?
A:Too short time: insufficient coating thickness and poor protection performance.
Too long time: too thick coating is prone to cracking, increasing costs and may lead to the risk of "hydrogen embrittlement" (especially for high-strength steel parts).
Key points of control: Calculate the time according to the coating thickness requirements (such as environmentally friendly galvanizing is usually 3-8 μm, and military electroplating can reach 10-25 μm), and adjust it in combination with current density.
Q:How does the bath temperature affect the quality of electrogalvanizing?
A:Too low temperature: The conductivity of the plating solution decreases, the deposition speed is slow, and the coating is prone to stripes or graying. ◦ Too high temperature: The plating solution evaporates quickly, the decomposition of additives is accelerated, the coating is rough, and the crystals are coarse.
Control points: Most processes require constant temperature control (such as acid potassium chloride zinc plating requires 20-50℃, and alkaline zincate zinc plating requires 15-45℃).
Q:What impact will it have if the pre-treatment (degreasing, rust removal, activation) is not done cleanly?
A:Incomplete degreasing: Grease residue leads to poor adhesion of the coating, which is easy to blister and peel off.
Incomplete rust removal: Oxide scale or rust hinders zinc deposition, forming "nodules" or missed plating.
Insufficient activation: The passive film on the substrate surface is not removed, and the coating bonding is weak (for example, steel parts need to be activated with hydrochloric acid/sulfuric acid, and aluminum alloys need to be activated with hydrofluoric acid).
Q:What problems often occur in post-processing (passivation, sealing, drying)?
A:Passivation process: Chromate passivation (environmentally friendly alternative process such as chromium-free passivation) has a thin or uneven film, resulting in reduced corrosion resistance.
Improper pH value or temperature of the passivation solution, the film is easily dissolved or the color is abnormal.
Sealing treatment: Without sealing (such as organic coating or silane treatment), it is easy to rust in the salt spray test.
Drying temperature: Too high temperature causes cracking of the passivation film, and too low temperature causes residual moisture to cause white rust.
Q:What is the core logic of electrogalvanizing quality control?
A:1. Pretreatment is the basis: thoroughly remove oil and rust to ensure the surface activity of the substrate.
2. Plating solution management is the core: accurately control the composition, impurities and process parameters, and perform regular maintenance.
3. Equipment and operation are the guarantee: ensure good conductivity, uniform stirring, and standardize the use of hangers and anodes.
4. Post-treatment is the key: improve corrosion resistance through passivation and sealing to avoid secondary pollution.