Normal temperature blackening mechanism is no consensus currently, because the black membrane is thin, usually no more than 3μm, use X-ray diffract meter and scanning electron microscope to analysis, normal temperature blackening film composition is not as alkaline black membrane Fe3O4, but its film layer components are more complex, it is difficult to make accurate judgments. The main technical indicators are: blackening agent is blue liquid, it’s no mechanical impurities, odorless, non-flammable, non-explosive, and non-corrosive, transport safety, its PH value is 2-2.5, the density is 1.04, and water insoluble matter is less than 1%. Its performance indicators are as follows: reference standards promulgated by the Ministry of Ordnance WJ535-82 <steel parts alkaline chemical oxidation technology>. After the black, the test results: 1. Experiment with 3% copper sulfate drip, discolored time is less than 32 seconds under 15-20℃. 2. Immersed it in the 3% sodium hydroxide aqueous solution for 2 hours will meet the standards.

The use methods: Framing→Degreasing(5-10mins)→Water rinsing(1min)→Rinsing(0.5min)→Derusting(1-5mins)→Water rinsing(1min)→Rinsing(0.5min)→GT-FH802 normal temperature blackening(2-6mins)→Water rinsing(1min)→Stabilizing(0.5-1min)→Immersing GT-FX238 rust oil dehydration(3-5mins) or GT-FB806 waterborne sealers(1min)→Drying or drying under 80-90℃(10-20mins). Pretreatment process including degreasing and rust-activated two processes, this is the key to black successfully in normal temperature, the general requirement is that the process black steel pipe should be degreased and rust thoroughly, only then can we get good black membrane. The circuit is: Medium temperature oil removing→Water rinsing→Rinsing→Derusting activation in normal temperature, light rust machined parts can use hydrochloric acid(the rate of industrial hydrochloric acid and water is 1:1), acid pickling 1-5mins, oxide scale thicker parts, can be derusted in 180-250g/l heated sulfuric acid→Water rinsing→Rinsing→GT-FH802 normal temperature blackening(this process is suitable for little oil, no thick Oxide scale parts, the processing time of each process in place, stable quality and low cost.). After learning the steps to operate the black steel pipe, you can use it correctly!