Electroplating is the process of electrical precipitating the metal to the substrate of an overlay with the chemical properties… Meet the desired requirements.
What is electroplating?
Electroplating is the process of electrical precipitating the metal to the substrate of an overlay with the chemical properties… Meet the desired requirements.
This process do in electroplating pool.
In it: the need for plating is tied to cathode, metal plating with the anode-positive of the power source in the dielectric solution.
The positive power will get the electrons e-during oxidation and release of the positive metal ions, under the electrostatic effect these positive ions will move to the negative, where they get back e-in oxidation deoxidation formation of the metal sticking to the surface of the object is plated.
The thickness of the coating is proportional to the current intensity of the source and the time of plating.
Metal surface machining before plating
Mechanical Machining
Mechanical machining is the process that makes the plated surface a uniform and high brightness, giving the coating a firm and beautiful grip. Mechanical machining can be carried out in many ways: grinding, polishing (is the process of grinding), suspension for small objects, combing, sand blasting or under-pressure waterjets the process of mechanical processing of surface metal products are deformed, reducing the adhesion of the coating later. So before the plating need to activate the surface in dilute acid then immediately galvanizing.
Degreasing
The metal surface after many stages of mechanical production, often grease, although very thin, well enough to make the surface becomes hydrophobic, contactless with detergent solution, galvanizing solution… Grease removal can be carried out in the following ways: remove in organic solvents such as Tricloethylene C2HCl3, C2Cl4 tetracloethylene, Carbontetrachloride CCl4… They are characterized by a good solubility of many types of fats, not corrosion metals, do not catch fire.
However, after evaporation of the solvent, on the surface of the metal remains a very thin layer of grease oil = > Not clean, be careful to bleach in alkaline solution. Bleach in hot alkaline solution NaOH has a few additional emulsifiers such as Na2SiO3, Na3PO4… With organic plants of animal origin will join the soap reaction with NaOH and be separated from the surface.
With mineral fatty oils, it will be separated under the emulsification effect of Na2SiO3. Bleach in alkaline solution by electrochemical method, under the action of electric current, oxygen and hydrogen exit have a bench effect under the particles of grease sticking to the surface. By this method the alkaline solution needs only more dilution than chemical eraser has been effectively achieved.
Ultrasonic grease removal is using ultrasonic waves with a large oscillation frequency that works on the metal surface, the strong vibration will help the grease to separate the layer easily.
Rust Remover
The surface metal is usually coated with a thick layer of oxide, called rust. Chemical Rust Remover for ferrous metals commonly use dilute H2SO4 or HCl or their mixture. When the eraser usually takes place simultaneously 2 process: dissolve oxide and metal background. Electrochemical pickling is the rust removal chemical at the same time with current involvement. May conduct cathode rust or anot pickling.
The anot removal of the surface layer will be very clean and slightly roughened so the coating will bind very well. Removal of cathode will give birth to a newborn, which is a partial reduction of oxide. Hydrogen was born as a oxide membrane mechanics and it would be flaking out. The cathode pickling is only applied to carbon steel plating, but with Ni-plated materials, Cr is not very efficient.
Electrochemical and chemical polishing
Electrochemical polishing for higher gloss machining. The coating on it attaches well, small crystals, fewer punctures and produces distinctive optical properties. When electrochemical bleaching often have bleach with anot placed in a special solution. Due to the dissolving speed of the larger convex part of the concave, the surface is leveled and smoothed.
The chemical balloon removal mechanism is also the same as electrochemical polishing. When chemical scrubs also appear thin film layer interferes or suppressions the effect of solution with metal at the recessed spot.
Gentle Cleansing
Mild cleansing also known as surface activation, to take away the very thin layer of oxide, which is not visible, is formed during machining just before the plating. When the removal is done, the crystal structure of the background is exposed, the attachment increases.
