What Are the Different Types of Plating Supplies?

Alloy plating is the process of plating a thin layer of alloy on the surface of some metals using the principle of electrolysis to obtain better material properties. It is a process that uses electrolysis to attach a metal film to the surface of a metal or other material. It can prevent metal oxidation (such as rust), improve abrasion resistance, electrical conductivity, light reflectivity, corrosion resistance (copper sulfate, etc.) and improve aesthetics.

When plating, plated metal or other insoluble materials

The coating is mostly a single metal or alloy, such as titanium palladium,

Electroplating requires a low-voltage, high-current power supply to the plating tank, and an electrolytic device composed of a plating solution, a part to be plated (cathode), and an anode. The composition of the electroplating solution varies depending on the plating layer, but each contains a main salt that provides metal ions, a complexing agent that can complex the metal ions in the main salt to form a complex, a buffering agent for stabilizing the pH of the solution, an anode activator, Special additives (such as brighteners, grain refiners, levelers, wetting agents, stress relief agents and fog suppressants, etc.). The electroplating process is a process in which metal ions in a plating solution are reduced to metal atoms by an electrode reaction under the action of an external electric field, and metal deposition is performed on a cathode. Therefore, this is a metal electrodeposition process including liquid phase mass transfer, electrochemical reaction and electrode crystallization.

In the plating tank containing the plating solution, the to-be-plated part after cleaning and special pretreatment is used as the cathode, and the anode is made of plated metal, and the two poles are respectively connected to the positive electrode and the negative electrode of the direct-current power supply. The plating solution is composed of an aqueous solution containing a metal to be plated, a conductive salt, a buffer, a pH adjuster, and an additive. After the current is applied, the metal ions in the plating solution move to the cathode under the action of the potential difference to form a plating layer. The metal of the anode forms metal ions into the plating solution to maintain the concentration of metal ions being plated. In some cases, such as chromium plating, it is an insoluble anode made of lead and lead-antimony alloy, which only plays the role of transmitting electrons and conducting current. The chromium ion concentration in the electrolyte needs to be maintained by periodically adding chromium compounds to the plating solution. During electroplating, the quality of the anode material, the composition of the plating solution, the temperature, the current density, the energization time, the stirring intensity, the precipitated impurities, and the power waveform will all affect the quality of the plating layer, which needs to be controlled in a timely manner.

Alloy plating high corrosion resistant zinc alloy plating process

Zinc alloy refers to an alloy containing zinc as a main component and containing a small amount of other metals. Binary zinc alloys that have been used for production are: Zn-Ni, Zn-Co, Zn-Fe, Sn-Zn. Zn-Ti, Zn-Cr, Zn-P, Zn-Mn, etc. are still under development and trial application. Zinc alloys have good protection properties, so they are often called high-corrosion-resistant alloy coatings, of which there are many studies and applications The more widespread are mainly alloys of zinc and iron group metals, namely zinc-nickel, zinc-cobalt and zinc-iron. The iron group metals have similar atomic structures and properties, and their co-deposition characteristics with zinc-forming alloys are similar. From the perspective of electrode potential, the potential of the iron group metal is more positive than that of zinc, but during co-deposition, zinc is easier to deposit than the iron group metal and is preferentially deposited. This type of deposition is called abnormal co-deposition. The reason is that when zinc and iron group metals are co-deposited on the cathode surface, with the precipitation of H2 on the cathode surface, the surface pH increases, and a zinc hydroxide colloid film is formed on the cathode surface, causing iron group metal ions to be exposed on the cathode surface. Inhibited and difficult to deposit, zinc was preferentially deposited on the cathode surface.

- Alloy electroplating zinc-iron alloy process and passivation treatment

There are two types of zinc-iron alloys that have obtained industrial applications: one is an alloy with high iron content, the coating is not easy to passivate, easy to phosphatize, and has good binding force to paint; it is mostly used for surface treatment of steel plates and strip As the bottom layer of electrophoretic paint; the other is a zinc-iron alloy containing trace iron. The coating is easy to passivate and has excellent corrosion resistance. Especially after black passivation, its corrosion resistance is greatly improved. The zinc-iron alloy process can also be divided into two types, acidic and alkaline. The iron content of the alloy coating is generally between 0.2% and 0.7%. The content of ferric ions in the plating solution cannot be too high, otherwise the cathode current efficiency will be reduced. Crystals are coarse. The following describes only the low iron content plating process ^[2] .