The factory's best-selling room temperature iron-based phosphating solution, steel surface treatment phosphating agent

KRB-L100 Iron-based phosphating solution 1.0 Scope of application This process is suitable for surface treatment of steel products before painting, so that a layer of water-insoluble colored phosphating film can be formed on the surface of the product to inhibit corrosion. And ensure good adhesion between the coating and the substrate. Treatment can be done by soaking or spraying at room temperature. 2.0 Materials and Reagents KRB-L100 Color Phosphating Agent 0.1N Sodium Hydroxide Standard Solution Bromophenol Blue, Phenolphthalein Index 3.0 Equipment Phosphating Tank: Lined with resin fiberglass anti-corrosion layer Washing with water → phosphating → (washing) drying or drying → spraying, etc. Phosphating: use KRB-L100 phosphating solution 5-10%, water 90%-95% to prepare color phosphating working solution. Soak the workpiece in it for 3-10 minutes. Drying: Dry, sun dry or blow dry, taking care to remove excess moisture from the workpiece. Inspection: The appearance of the phosphating film should be in various colors and have a certain luster, and there must be no rust, loose film layer, sticky residue, excessive hanging ash, etc. Clean the surface of the workpiece: The surface of the cleaned workpiece should be free of rust, dust particles, and adhesive residues, and then paint. The time interval between phosphating completion and painting shall not exceed 16 hours. Notes: A. Master the phosphating time and supplementary materials according to the color of the phosphating film. B. Control the free acidity of the phosphating solution to not less than 0.7 points. If the free acidity is insufficient, the phosphating agent should be supplemented. Every addition of KRB-L100 2kg/m3 can increase the free acidity by 0.1 points. During the working process, iron continuously enters the solution from the workpiece, so the iron content and total acidity in the phosphating solution gradually increase. At this time, the film-forming (coloring) speed of the workpiece will be slowed down, and if it is dried with liquid after phosphating, it will easily cause dust accumulation. When the iron content in the phosphating solution is greater than 1.5g/L, it is advisable to use water washing after phosphating, re-passivation, and drying. When the iron content is ≥3.0g/L, or the total acidity is ≥36 points, it is recommended to replace part or all of the phosphating solution. 5.0 Solution analysis and detection method 1. Chemical titration of total acidity a: Use a graduated pipette to draw 5.00ml of phosphating solution, pour it into a conical flask, add 50ml of water and 2 drops of phenolphthalein indicator, and titrate with 0.1N NaOH (sodium hydroxide ) The standard solution turns stable red as the end point, record the number of milliliters of the standard solution consumed in the titration A=2V (point) Free acidity b: use a graduated pipette to draw 10.00ml of phosphating solution, pour it into a conical flask, add 50ml of water and 4 drops of bromophenol blue indicator, titrate with 0.1N NaOH standard solution until the yellow color disappears (blue or green under fluorescent light; blue or purple under iodine tungsten lamp or sunlight) ), record the standard solution consumed in titration in milliliters Number, V. B=V (point) The free acidity of the working solution prepared with a concentration of 5% should be greater than 1.0 point, and the pH value should be less than or more than 3.5. 2. Cold plate test piece method After completely degreasing a small piece of cold plate (you can thoroughly scrub it with a rag in the degreasing tank), immerse it in the phosphating tank for 1 minute, take it out and let it stand, and observe the color of the test piece after natural drying: A 2. If the color of the test piece is darker, mainly dark purple and dark green, it means that the concentration of the phosphating tank is too high. B. If the color of the test piece is blue-purple, it means that the concentration of the phosphating tank is moderate. C. If the color of the test piece is light blue-white, it means that the concentration is insufficient, and a phosphating agent needs to be added.