Nickel anode is a nickel strip (sheet) made in the form of a rectangle or an oval. This type of product belongs to the sheet nickel rolled nickel, which is quite popular in the industry.
Characteristics
In industrial production to classify nickel anodes use division:
According to the type of cross-section. One can buy nickel anodes with rectangular (PR) and oval (OV) cross-sections; by length. A distinction is made between nickel anodes, cut to measure (MD), cut not to measure (ND) and multiples, cut to measure; By accuracy of fabrication. Products of normal (N) and increased (P) accuracy are classified.
For high-precision anodes with rectangular cross-sections, the main criterion for compliance with GOST is the thickness. There is a dependence of the thickness of nickel strip and the value of its limiting deviation. Namely:
- for a thickness of 4 to 8 mm deviation of 0.2 mm;
- for a thickness of 10 mm deviation of 0.3 mm;
- for thickness 12, the deviation of 0,4 mm.
The difference of nickel oval anodes is the presence of 10 or 12 mm holes at the ends of the product. Oval anodes are produced in lengths of 400 to 500 or 700 to 1200 mm.
It is possible to produce products with a non-dimensional length (ND) of less than 400 mm. This dimension must be present in every production batch.
Production of nickel anodes
Anodes with rectangular cross-sections are produced from nickel grades NP-1, NP-4, NPA-1, NPA-2, and NPAAN in accordance with GOST 492-2006. The most often used semi-finished anode nickel NPA-1 includes 99.7% of pure nickel and alloy NPA-2, where 99% of the metal.
The abbreviation NP stands for semi-finished nickel, H for non-passivated, and A for anode nickel.
Nickel anodes are standard nickel sheets (strips). The method of manufacturing nickel sheets is hot rolling on rolling mills. The thickness of the finished product determines the number of rolling cycles. The thinner the output sheet, the greater the number of times the raw material must be rolled. During the technological process, the billet is heated.
After a semi-finished material of a certain thickness is obtained, the following operations are performed:
- chemical treatment;
- Heat treatment (hardening for NPAN anodes);
- Mechanical processing (trimming edges, making holes, etc.).
- Indelible marking (grade, lot number);
- transportation.
Nickel anodes are transported without packing. Anodes should be stored in a dry room, and protected from chemicals and mechanical damage. Observing the storage and transportation conditions, nickel anodes’ properties remain unchanged.
The presence of impurities in the form of lead, antimony, bismuth and others affects the properties of nickel anodes, reducing the mechanical and technological parameters of the product. Therefore, reducing the number of impurities in the metal is a priority in the production of this type of rolled metal.
For example, the presence of sulfur impurities in the alloy leads to the formation of a sulfide film on the strip surface. The film melts at +645°C and increases the brittleness of the metal. This phenomenon, called “hot brittleness,” reduces the quality of the alloy.
