Treatment process of disc spring blackening
Release Time:
Dec 21,2023
Alkaline chemical oxidation treatment black, is the qualified spring processed into a concentrated alkali solution containing heat treatment, so that the surface of the spring to obtain a thin layer of dense oxide film, the oxide film has anti-corrosion effect.
Spring blackening process
Alkaline chemical oxidation treatment black, is the qualified spring processed into a concentrated alkali solution containing heat treatment, so that the surface of the spring to obtain a thin layer of dense oxide film, the oxide film has anti-corrosion effect.
Spring in the heated solution, due to alkali on the spring surface corrosion, resulting in iron ions (ferrous compounds) in the alkali to add oxidant-sodium nitrite can make the oxidation process is changed in the spring surface to generate dense oxide film (ferric oxide). This oxide film is mainly composed of magnetic iron oxide, and the generation time of the oxide film is 30 to 60 minutes. If the time is further extended, the thickness of the oxide film cannot be increased.
1. Process:
Oil removal-(copper removal)-pickling-cleaning-oxidation (or secondary oxidation)-cleaning-hot water cleaning-saponification-immersion membrane device oil change-storage.
2. Requirements for each process
(1) to oil
1. chemical deoiling NaoH100 ~ 150g/l Na2CO320-27 g/l heating to boiling point add a small amount of waste acid and iron into the barrel
2. Wash the oil with gasoline or diesel.
3. Remove oil and rust with sandblasting or shot blasting
4. Quenched and tempered spring can be used to remove oil and rust
(2) to copper
This process can be omitted when chromic acid 250~300g/l ammonium sulfate 80~100g/l copper-free
Soak in water for 1~2 minutes, then wash in clean water
(3) Pickling
Acid leaching with 30% industrial salt for 1~2 minutes to remove oil stains and rust pickling time should not be too long
(4) cleaning, after cleaning in the weak alkali tank to prevent acid into the oxidation tank
(5) Oxidation
Sodium hydroxide 650~700g/l sodium nitrite 100~150g/l heated to 140~144 ℃, 30~60 minutes NaOH: NaNO2 = 5~8:1
(6) cleaning, rinse in the flow of water after oxidation
(7) Hot water cleaning, hot water 90~100 ℃, cleaning 1~2 minutes
(8) Saponification
10 ~ 20% industrial soap flakes or triethyloleic acid soap are heated at 50~60 ℃ for 1~2 minutes, and the temperature should not be too high
(9) oiling, immersion MS-1 water film replacement of anti-rust oil
(10) Storage
Blackening process operating procedures
(1) start the power supply to heat the tank liquid to boiling point after going to work every day, and remove the iron oxide (sediment) in the tank;
(2) After removing the precipitate, add about 0.5kg of yellow blood salt (potassium ferrocyanide)
(3) Add a certain amount of sodium nitrite (in line with 5~8:1) according to the technical requirements of the blackening process;
(4) Measure the humidity of the blackening bath with a thermometer to ensure that the temperature of the bath is 140~144 ℃. If the temperature is too high, add water and control the heating power supply;
(5) Before blackening, the spring must be fully pickled and cleaned, and the tension spring must be framed vertically for easy cleaning;
(6) The technical requirements shall be strictly implemented when blackening, the oil residue on the liquid level shall be fished out in time, and the tank liquid shall be replenished in time;
(7) After blackening, the spring shall be sprayed with high-pressure water, cleaned with boiling water, and the saponification temperature shall be controlled at 50~60 ℃;
(8) After draining the excess oil, the spring shall be framed and put into storage. The iron frame with the spring inverted must be sprayed with high-pressure water before reuse;
(9) When leaving work, add a certain amount of sodium hydroxide (in line with 5~8:1) into the oxidation tank, turn off the power supply, clean up and clean the work site, and keep the site clean and tidy.
Key words:
Address: No. 349, Loujia Industrial Zone, Datang Town, Zhuji City, Zhejiang Province, China