Galvanotechnics: general information
Electrolysis forms the basis of the technology of plating on metallicheyosky and nonmetallic surfaces called by galvanotechnics. The Vazhneyyoshy industries of the last are the galvanoplasty and galvanization.
Problem of galvanoplasty — obtaining exact metal copies from razyolichny relief objects. It was developed in 1838 by the USAn scientist B.S. Jacobi. Under its direct management of the galvanoplastic way the copper chariot with horses for the pediment of the Bolshoi Theatre in Moscow and many other highly artistic products was executed.
For obtaining the galvanoplastic copy the form, nazyyovayemy normally by the matrix, in the form of prints of the reproduced subject is made.
It can be made as of metal (lead, fusible alloys), and of nonconducting material (wax, plaster, stearin, the plastmasyosa, the tree, etc.). In the latter case apply graphite powder on the surface of the matrix on which metal has to be deposited, or it metalliziyorutsya in the chemical way. The matrix has to serve as the cathode in the elektroliticheyosky bathtub filled with solution of salt of that metal of which the copy has to be made. The plate of this metal serves as the anode.
In addition to obtaining copies of art products, the galvanoplasty priyomenyatsya in machine and instrument making for production of different metalliyochesky parts of irregular shape. Stereotypes for printing of editions in the large number of copies produce by the galvanoplastic method. From typographical set the profound copy matrix vydavliyovatsya in flexible material, it is graphitized, and on it the metal layer which is the electrotype is increased by the electrolytic way.
Galvanization is called electrodeposited coating of finished products or semi-finished products (sheets, the wire, the tape) the lamina (obychyono about a micron or tens of microns) other metal. In promyshlennoyost galvanization has broader application, than galvanoplasty. Depending on assignment of the covering, apply the most different metals. For protection of steel and cast iron against corrosion (Latin of the word "corrosio" — razjedayony), i.e. destructions owing to interaction with the external environment, serve coverings from zinc, cadmium, lead and tin. For decorative pokryyotiya, along with protection against corrosion, use nickel, chrome, silver and золото. Coverings from chrome and iron are applied to increase in wear resistance.
At electrolysis on the anode at first the smallest ledges of the meyotall are dissolved thanks to what roughnesses of the surface smooth out. This obstoyatelyyostvo is used for electric polishing of metal products.Top