The cuprous ionsin the plating solution are mainly affected by the strong reaction and strong reaction of anodic oxidation. Although the water content is very slim, only very few can harm the coating quality. Cuprous ions entering the tank will cause harm to the incidence of cathode coating:
1, the composition of coating raw edge is not smooth. In the process of electroplating process system, the vermicellite is deposited on the cathode coating by the method of electrophoresis. Under the condition of low current intensity and high temperature, the output power of cathode current flow will decrease, and the charge and discharge of hydroxide ion will reduce the acid value. The strong reaction direction of hydrolysis reaction will be carried out in the direction of beneficial vermicellae conversion, and the condition of raw edge will be aggravated.
2, cuprous ions together will form the coating is not bright, smooth ability is poor, the bath turbidity. This is because of the delicate dispersion of vermicelli on the cathode coating, forming the delicate ability of the accumulation layer is poor, dull. In low-flow areas, the damage is even worse. At this time, the effect of adding light agent is not large, adding hydrogen peroxide to remove vermicelli, completely drive hydrogen peroxide, fill light agent, regional brightness and flatness will be significantly improved. A strong reaction will consume part of the acid, should be appropriate to fill some hydrochloric acid.
The water content of phosphorus in anodizing is more than 0.3% in China, and the overseas discussion shows that the water content of phosphorus in anodizing nickel alloy reaches about 0.005%, which is composed of black film, but the film is too thin and the binding is not good. The water content of phosphorus is too high, the black film is too thick, the anode mud is too much, the anode oxidation solubility is poor, resulting in the reduction of the copper water content in the plating solution. The moisture content of phosphorus in anodic oxidation is 0.030-- 0.075%, and the best is 0.035? The production equipment and processing technology in China are out of date, and the mixing is not balanced, which cannot ensure the balanced distribution of the phosphorus water content. The phosphorus water content is usually increased to 0.1-0.3%. Overseas, titanium electrode or T2 anaerobic copper and phosphorus alloy copper as materials, with medium frequency induction furnace smelting, high purity of materials, phosphorus water content is easy to manipulate, the use of medium frequency magnetic induction, magnetic stirring effect is good, copper and phosphorus melting mixing symmetry, automatic operation, so made copper anodized phosphorus dispersion symmetry, symmetry melting, detailed crystals, thin crystals, High anodic oxidation application rate is beneficial to polishing and brightening of coating, reducing burring and non-smooth defects.
Harm of phosphorus moisture content to anodized phosphorus films
1. Water content of phosphorus is 0.030? 0.075% copper anodized, composed of black film thickness moderate, delicate structure, solid fusion, not easy to fall; Copper anodizing with excessive phosphorus water content before risk. Phosphorus dispersion is not symmetrical, melting makes anode mud too much, and then the environment pollution tank, but also block the anode oxidation bag hole, the composition of the tank working voltage rise. The working voltage of the tank will rise and the anodic oxide film will fall. In practice, electroplating process is used to disassemble and replace anodic oxidation simple diseased edges.
2. The anodized phosphorus dispersion of nickel alloy with 0.3% phosphorus water content is uneven, the gray black phosphorus film is too thick, and the solubility of copper is poor. Therefore, it is often necessary to fill the anodizing, not to make the ratio of the total area of the positive cathode 1:1, the practice of copper anodizing hanging more, the copper water content in the tank also has the development trend of reducing, but also can not adhere to the balance. Often add copper sulfate, from the plating process cost, is not cost-effective. Electroplating process would rather hang more residual nickel alloy anodizing, anode mud increase, the cost of practical activities will increase.
3, practice activities on the high phosphorus water content of copper anodizing into the black film is too thick, plus resistor, to maintain the original current flow, working voltage to rise. The increase of the working voltage of the tank is beneficial to the charge and discharge of hydroxide ion, and the incidence probability of needle eye increases. This situation has implications for the country ". AEO "system software is rare, because there are more surfactants on the surface, but for some imported light agent, the opportunity of the needle will be greatly increased, need to add other moist-cooling agent, and try to reduce the working voltage.
4. In practical activities, the phosphorus water content is high, the black film is too thick, the dispersion is not symmetrical, but also the formation of low current flow area is not bright, thin hemp sand.
Although the thickness of the black anodized film containing 0.3% copper phosphorus can reduce cuprous ions into the tank, but because of its loose structure, the dispersion is not symmetrical, the efficacy is greatly reduced. Other lithium battery electrolytes have strong effects of organic chemical reversibility:
Cu2++ Cu -→ 2Cu+
At room temperature, the equilibrium constant of this strong reaction is K= (Cu+) 2/ (Cu2+) =0.5X10-4
As the temperature goes up, so does the concentration of cuprous ions. Cuprous ions are stored in the tank in the form of cuprous hydrochloride and are oxidized by air during gas agitation. When the acid value decreased, cuprous oxide (vermicrite) was hydrolyzed by cuprous hydrochloric acid reaction, and the same powder remained in the cathode area of high current flow. In the low current flow zone, the output power of current flow decreases, the charge and discharge of hydroxide ions are more, the relative acid value decreases, and the hydrolysis reaction develops towards the direction of conversion to vermicelli.
More vermicelli lingering on the cathode surface will be composed of cathode coating is not bright, fine hemp sand. If there is no gas stirring, the more the current intensity is not big, this situation is very sick in the low current flow area.
The application of copper anodizing with less phosphorus water content, because the gray black phosphorus film is delicate, cuprous force can not be integrated into the tank, as long as the gas stirring, the control of hydrochloric acid concentration value need not be slightly lower, the current intensity is slightly higher, not only the amount of the area and hemp sand can be defeated.