1. Rust removal
The rust level and rust removal level of the steel surface are determined visually according to (IB8932--88, and the surface rust is divided into four levels: A, B, C, and D:
A: The collar surface is fully covered with scale and almost no rust;
B: The surface of the steel that has been corroded and partially oxidized has peeled off;
C: The degree of oxidation has fallen due to rust, or it can be scraped off, and there is a small amount of pitting on the surface of the collar
D: The oxidation degree has been comprehensively sharpened due to corrosion, and pitting corrosion has generally occurred on the surface of steel materials. For the surface of sand and batch derusting, it is divided into four grades: Sa1, Sa2, Sa2.5, and sa3, of which Sa2. Grade 5 is a very effective rust removal treatment, but there are slight stains; sa3 grade is a clean treatment with a uniform metallic color.
For manual and power tool rust removal, there are two grades: St2 and St3. St3 is a very effective rust removal treatment.
For pickling and derusting, please refer to JB/T6978-93 "Surface Preparation Before Deinstallation - Pickling".
2. Degreasing
The degreasing degree of steel surface shall be determined according to GB/T13312-91. In this method, drop 2 drops (0.1m1) of the standard G-type polar solution on the surface to be tested, immediately use the glass rod method to form a coverage area of 20mmx40mm, and stick the special A-type oil test paper on the solution film for 1min After observing the discoloration, if the color of the A-type oil test paper is uniform and continuous, it is qualified, otherwise it is unqualified.
3. Phosphating
The inspection of the phosphating film is carried out according to GB6807--86, and the cacao is soaked with 3% sodium chloride aqueous solution at 15~25°C, or dripped with sulfuric acid solution. It can also be assessed by salt spray test after painting. The formula of copper sulfate spot flooding solution is as follows: CuS04 5H2041g/L, Nacl35g/1 0.1tno1/L Hot 13m1/L.
4. Aluminum surface passivation
Rinse and no-rinse chromate passivation treatment of aluminum surface can be tested according to IS010546-1993 (E), in which no-rinse chromate is used for surface passivation treatment before painting, pre-dried at 65°C after treatment, and then The second step of drying is carried out at 100~110°C. The inspection items include: mass per unit area of the film layer, neutral salt spray test, and film adhesion. The weight of colorless film is 0.05~0.2g/I, the weight of yellow film is 0.2~1.3 g/L (colorless to iridescent), the film of 0.4 g/L can be colored, and the yellow film is used as the coating base. Chromates are light green (colorless to green) and are also used in pre-paint treatments.
