Stainless steel has excellent chemical stability and good corrosion resistance. Therefore, it is widely used in the electronics industry, household kitchenware, decoration and small hardware stores. However, in special applications, in order to give the stainless steel surface some special physical and chemical properties, such as conductivity, wear resistance, beautiful appearance.
Author: Marisa
The electroplating process of stainless steel mainly consists of degreasing, impregnation, activation, pre-plating and electroplating. Among them, degreasing, impregnation, activation and pre-plating belong to the pre-treatment process. Since oil, oxide scale, hydroxide, dust and other dirt will adhere to the surface of the plated parts during manufacturing, processing, handling and storage, these substances will affect the bonding strength and protection of the coating. Therefore, before electroplating, these substances must be removed to expose the fresh substrate of the plated parts to obtain good subsequent electroplating coating performance. Therefore, pre-treatment plays a decisive role in the entire electroplating process. It is an indispensable process for surface treatment before electroplating and an important link to ensure the quality of the electroplating coating.
When the surface of the plated parts is seriously oily, organic solvents such as gasoline should be used for cleaning. When the oil pollution is less, chemical degreasing, electrochemical degreasing, etc. can be used.
(a) Chemical degreasing: sodium hydroxide 60-80g/L, sodium phosphate 20-40g/L, sodium carbonate 20-40g/L, sodium silicate 3-10g/L. Total alkalinity 65-100g/L, temperature 70-90℃, time until all oil is removed.
(b) Electrochemical degreasing: sodium hydroxide 30-50g/L, sodium phosphate 20-30g/L, sodium carbonate 20-30g/L, water glass 3-5g/L. Total alkalinity 40-60g/L, temperature 60-80℃, current density 3-10A/dm2, time: cathode 3-5min, anode 1-5min, electrode material steel plate or nickel-plated steel plate.
Large-sized stainless steel products, such as composite plates, large pressure vessels, etc., cannot be placed in the degreasing tank for degreasing. They can be wiped and degreased with a rag or mop dipped in a room temperature degreasing agent, washing powder, etc. aqueous solution. For parts with large batches, small size and light weight, it is better to use a drum for degreasing. Put these parts in the drum and add appropriate abrasives and degreasing agents for degreasing. The effect is good, the cost is low, and the operation is convenient, but it is not suitable for thin parts that are easy to deform.
The standard for clean degreasing is: after degreasing and washing, the water film does not crack for 30 seconds.
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