Industrial casters hard chromium plating type 1, in the strict control of temperature and current density,
Relatively high decorative chromium plating)
Conditions, from chromium plating liquid of high hardness, wear resistance good hard chromium layer.
2, opal chromium by changing the working conditions of the chromium plating solution, the less porosity, has a high resistance to corrosion, and low hardness of ivory chrome plating.
Oxidation and passivation, anodic oxidation, usually refers to the aluminum or aluminum alloy products or parts, in a certain electrolyte and specific working conditions as anode, by the effect of direct current, make its surface to generate a corrosion resistant layer of oxidation film process.
2, phosphating of iron and steel parts in a solution containing the phosphate chemical processing, make its surface to generate a layer of insoluble in water of phosphate coating process.
3, the blue steel parts in certain oxidation medium for chemical processing, make its surface to generate a blue-black layer of protective oxide film processing.
4, chemical oxidation in no current under the action of outside, metal parts and the electrolyte solution, to make it to generate a layer of oxide film on the surface of processing.
5, electrochemical oxidation with the metal parts into the electrolyte solution must be as the anode, under the effect of direct current (dc), make its surface oxidation film of the electrochemical process.
6, chemical passivation in no current under the action of outside, metal parts and the electrolyte solution, make its produce a passivation layer on the surface of the membrane process.
7, electrochemical passivation by immersion in the electrolyte solution metal parts as the anode, under the effect of direct current (dc), make its surface layer of passivation film processing.
Castor electroplating, current density generally refers to the electrode (1
Such as castor electroplating parts)
Through the surface of the current value per unit area, usually with A/dm2 as A unit of measure.
2, usually refers to a direct current flows through the electrodes, the phenomenon of electrode potential deviation from the equilibrium potential.
Under the effect of electric current, the anode electrode potential is the direction of migration, known as anode polarization;
Cathode electrode potential towards the direction of the negative offset, called cathodic polarization.
3, hydrogen embrittlement parts in electrochemical oil removal, strong erosion, such as castor electroplating process, due to be restored after the infiltration of part of hydrogen in the state of atomic hydrogen formed in the substrate metal or coating stress, decrease the toughness of the matrix metal and plating and produce the phenomenon of brittle.
4, rough coating as the main salt concentration, such as pH, temperature and current density control improperly, and solid impurity is overmuch, caused by the rough coating crystallization and slight uneven phenomenon.
5, burnt because of main salt concentration, such as pH, temperature and current density control improper, cause coating a spongy deposition, crystalline bulky loose and black phenomenon.
6, pinhole caused by a lack of embellish agent in plating solution, pH value is abnormal and excessive organic impurities and the hydrogen evolution on the surface of the plating and other reasons, causes the coating has the size of the needle pore phenomenon.
7, pitting due to excessive heavy metal impurities in plating solution or organic impurities, wetting agent and pH value is abnormal, the coating appear tiny pits, pointed convex or larger pore phenomenon.
8, the flower as additives, especially the brightener disorders, too much organic impurities, between process cleaning bad as well as the improper control of temperature and current density and so on reasons, causes uneven coating color, small piece of grey and dark.
9, peeling due to poor treatment before plating, too many impurities in plating solution, the improper control of pH and current density, coating and the magnesium substrate caused by combining, summon up or falls off phenomenon.
Plating post-processing 1, cleaning cleaning is an important process of plating processing.
One is to put the parts on the attached fluid clean, to ensure the anti-corrosion of coating or decorative performance;
2 it is to avoid the parts on the attached fluid into the next working procedure and cause pollution, and even make each working procedure in the process of castor plating defects, may also make the coating because of infiltration of plating solution and produce the phenomenon such as rust, white.
2, drive hydrogen is to eliminate the harm of hydrogen embrittlement, and USES the heat treatment, will be out of parts in the process of hydrogen.
3, passivation 4, its processing (coating
Main processing object is silver plating)
The measures to prevent coating color, it is the coating corrosion medium isolation with the outside world, or using other methods to improve corrosion resistance of the coating.
Commonly used the following methods: (
Generate a layer of protective film on the coating (
Such as chemical passivation, electrolytic passivation, electrophoresis, etc. )
In the coating deposited on a layer of precious metals (
Such as gold plated, rhodium, palladium, etc. )
, or castor has some discoloration resistance of silver alloy plating (
Such as silver and gold alloy, etc. )
This approach to material price is expensive, the cost is high, only used for high stability high abrasion resistance parts.
On the coating film covering a layer of organic materials.
This method has a lot to improve discoloration resistance of the coating, if cooperate with the first (
Methods to use, its effect is better.
But it on the contact resistance of the metal and welding performance have adverse effect, suitable for parts of electrical performance requirements is not high.
Dip on the coating layer to prevent corrosion inhibitor coating color, such as silver color agent TX type.
Its performance is good, the method of metal welding performance and the influence of contact resistance is small.