Home > News > Industry News > Black processing


Black processing

  • Author:Memory
  • Source:www.xy-global.com
  • Release on:2017-11-15
BlackIs a chemical surface treatment of a common means, the principle is to produce a layer of metal oxide film surface to isolate the air, to achieve the purpose of rust. Dark appearance can be used when the appearance of the request, the black surface treatment of steel parts, but also known as bluing.
Blackening commonly used methods are the traditional alkaline blackening and the emergence of late at room temperature blackening two. But at room temperature blackening technology for the effect of low carbon steel is not very good. Alkaline black subdivided, there is a black and black the difference between the two. The main components of black liquor is sodium hydroxide and sodium nitrite. Black when the required temperature tolerance, probably between 135-155 ℃ can get a good surface, but some of the required length of time only.
(1) Black safe without electricity, black with alkaline heat needs 100% electricity. (2) to improve ergonomics: a total of 1-2 hours. (3) Blacking low cost, simple equipment, easy to operate; strict control of blackout time. (4) process adaptability: Solve the problem of ductile iron can not be black.

A bearing ring bevel and flange blue hair rust treatment process. The bearing rings pass after heat treatmentDegreasingAnd then a mixed solution of sodium hydroxide, sodium nitrite, sodium nitrate, and water-color processing, the ratio of 2-3:1, the remaining water was added; add water to a suitable temperature at 135 ℃ -145 ℃; time 15-25 minutes; remove the ferrule rinse after passivation treatment, passivation treatment with potassium dichromate solution as a filling solution, the concentration of 12% -18%; at room temperature for 1-2 minutes; passivation After treatment and drying, put in 105 ℃ -120 ℃ oil or rust-proof oil for 1-3 minutes until the bubbles disappear completely and park for 10-15 minutes after the test. The oxide film produced by the process has the advantages of stable performance, long-term protection of the ferrule at room temperature, chamfering at the edge, and no rust at the ribbing edge, and obviously improves the appearance quality of the bearing.

A3 steelAlkaline black better.

In practice, what should be noticed is the quality of rust removal and degreasing before the workpiece is blacked out, and the passivation immersion oil after blackening. The quality of blackening is often due to these processes and changes.