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Dispersion capability TP and coverage capability CP

1.The ability of coated metal to deposit evenly on uneven surfaces of workpieces is called throwing power.In other words, the dispersibility refers to the ability of the solution to evenly distribute the thickness of the coated surface, also known as the uniform plating ability.
2, the ability to coat deep recesses of parts is called covering power, or deep plating ability, which is a concept used to illustrate the complete distribution of electroplating solutions on the surface of a workpiece.Microovering power refers to the ability of metal ions in the electroplating solution to electrodeposit in gaps or scratches under certain conditions
3.Generally speaking, good dispersion and good coverage are obtained.If the dispersing ability is poor, the covering ability will also be poor.However, if the coverage is good, the dispersion is not necessarily good.
4, Dispersion ability is only a concept used to describe how well the plating solution makes the coating thickness uniform on all parts of the workpiece surface, while deep plating ability is a concept used to describe how well the plating solution causes the coating to be plated on deep recesses of the workpiece, such as the inner wall of a tube, regardless of the factor of uniform coating thickness.This is the difference between dispersion and coverage.
5, whether the metal coating is evenly distributed on the workpiece and whether the coating is complete or not is an important factor to determine the quality of the coating.Thick, thin, uniform and complete coating with good protection performance;However, coatings with different uniformity, large thickness difference or discontinuous and poor integrity have poor protection performance.Therefore, improving the dispersion and coverage of plating solution is a key issue directly related to the quality of electroplating products.
6.The main factors that affect the dispersibility and coverage capacity are as follows:
(1) Geometric factors such as the geometry of the electroplating bath, the shape and size of the electrodes, the distance of the electrodes, and the way the electrodes are mounted in the slot;
(2) surface condition of base metal, mode of power on, size of hydrogen evolution overpotential, etc.;
(3) current efficiency on cathode;
(4) conductivity of plating solution;
(5) cathode polarization.
7.The following measures can be taken to improve the dispersibility and coverage of the plating solution:
(1) Hang the workpiece properly so that it is in the optimal current distribution state and avoid the gas trapped in the holes or depressions of the workpiece as much as possible;
(2) Improving the surface condition of matrix metals and increasing the overpotential of hydrogen on matrix metals by short-time impulse current;
(3) Improve the geometry of electrodes and electroplating slots as much as possible, and adjust the distance between electrodes reasonably;
(4) Add auxiliary poles to workpieces to improve current distribution;

The uniformity and integrity of the coating distribution on the cathode surface is an important factor to determine the quality of the coating.To some extent, it affects the protective performance of the coating.The uniformity and integrity of the metal coating distribution on the cathode are assessed by the dispersion and coverage capabilities commonly used in electroplating.
The dispersibility of electroplating solution (expressed as T.P) refers to the ability of a solution to distribute coatings on electrodes (usually cathodes) more evenly than the results obtained from the initial current distribution under specific conditions.It can be seen that the dispersivity is comparative, and the basis for comparison is the primary current distribution.The so-called primary current distribution only considers the distribution of cathode current at different geometric distances from the cathode surface to the anode.The higher the uniform distribution of the coating on the parts, the better the dispersion of the electroplating solution.The coating distribution on the macro-outline surface is discussed here.The concept of leveling ability can be used for the coating distribution on the micro-surface.The so-called smoothing ability (i.e.micro-dispersivity) refers to the ability of the plating solution to make the micro-outline of the coating smoother than that of the bottom layer when the coating is formed on the bottom layer (expressed by M.T.P).It expresses the uniformity of coating distribution on a surface where the roughness of the bottom layer is small, the depth of the cave is less than 0.5mm, and the distance between the peak and the valley is small.This property is very important for obtaining high quality glossy decorative coatings.
Coverage capacity of electroplating solution refers to the ability of electroplating solution to deposit metal coating in grooves or deep holes under specific conditions (expressed in C.P).It refers to the integrity of the distribution of the coating on the parts.The higher the coverage, the deeper the plating.Poor coverage prevents metal coating from being plated in the recesses of parts.
Distribution capacity and coverage capacity of plating solution have different meanings, so pay attention to the differences and do not confuse them.When expressing quantitatively the values of dispersibility and coverage, it is important to specify the measuring methods.The results of different methods cannot be compared.


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