Framing → HH102 high-efficiency degreasing agent to remove oil (5-10 minutes) → water rinse (1 minute) → rinse (0.5 minutes) → hydrochloric acid plus HQ301 normal temperature blackening pickling activation additive to remove rust (1-5 minutes) → HH902-IIA is rinsed with water (1 minute) → HH902-IIA is rinsed with water (0.5 minutes) → HH902-IIB steel turns black at room temperature (20 seconds-2 minutes) → rinsed with water (1 minute) → stable (0.5-1 minutes) → Soak in HH932 dehydrated anti-rust oil (3-5 minutes) / HH972 water-based sealer (1 minute) → dry at room temperature or dry (80-90°C for 10-20 minutes)
The pre-treatment process includes two processes
oil removal and rust removal activation. This is the key to the success or failure of normal temperature blackening. The general requirement is that the treated parts must be thoroughly deoiled and rusted to obtain a good blackening film.
The following process flows are recommended to choose from
Process 1: Medium temperature degreasing → water washing → water rinsing → normal temperature rust removal and activation (lightly rusted machined parts can be pickled with hydrochloric acid (ratio of industrial hydrochloric acid and water 1:1) for 1-5 minutes: parts with thick oxide scale, Rust can be removed in 180-250 g/L heated sulfuric acid.)→Water washing→Water rinsing→Blackening at room temperature (This process is suitable for parts with little oil stains and no thick oxide scale. The processing time of each process is in place and the quality is stable. low cost.)
Sandblasting→Washing→Blackening at room temperature
(This process is suitable for high-silicon steel, high-manganese steel, high-chromium steel and other parts with thick oxide scale, thick oil stains on the surface and difficult to be activated with acid. The sandblasting machine can be sealed or water-based sandblasting machine to protect the environment. , to achieve clean production. Sandblasting machine manufacturers have launched various models of products, and their performance has taken into account the requirements for clean production.)
Process 3: Ultrasonic degreasing → water washing → rust removal and activation → water washing → blackening at room temperature (applicable to parts with deep holes, blind holes and complex shapes.
Preparing the room temperature blackening treatment bath liquid: the finished product is a concentrated liquid, add 4 times of water (well water cannot be used) to dilute it into a working fluid. For parts made of loose materials such as cast iron, cast steel, powder metallurgy, etc., the working fluid should be added to 5 times of water. For other parts, the working fluid should be added 5 times. Add 4 times water to steel. The working fluid should be light but not thick. Adding less water is not good. Quickly immerse the cleaned parts with no oil or rust spots into the blackened working fluid. Lift the gap 2-3 times and take it out after 1-3 minutes. (The initial concentration of the solution is about 1 minute.) See black. It is enough that the film is evenly gray-black. After the blackened parts come out of the tank, stay in the air for 1 to 2 minutes before washing with water. This can make full use of the residual liquid on the surface and reduce the consumption of blackening agent. Rinse and rinse again with tap water.
Post-processing process
Choose one of three different treatment methods: (1) Dehydration and anti-rust oil sealing: Dip the parts that have turned black and washed and rinsed with water into dehydration and anti-rust oil for 3-5 minutes, and lift them up and down for 3 -After 5 times; (2) Hot soaking oil: soak in boiling water solution for 5 minutes, and then hot soaking in machine oil or various anti-rust oils can improve the corrosion resistance (the effect of soaking in dehydrated anti-rust oil is better) ( 3) Soak in sealer: High-end parts (such as photographic equipment, optical instruments) require high wear resistance and good gloss. They can be dehydrated in boiling water and then soaked in sealer. (Such as acrylic paint, polyurethane paint, etc.) Solution maintenance: When the efficiency of the blackening agent decreases, the blue-green color of the solution gradually fades, the pH value rises to about 2.8, and white precipitates are produced, indicating the aging of the blackening agent. At this time, you can filter and clarify, separate the precipitate, and then add the blackening agent stock solution (measure with pH 0.5-5 precision test paper) until the pH returns to the 2-2.5 range before continuing to use it. It is best to use double tanks, one tank for working and one tank for cleaning the sediment.
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