Phosphating is a commonly used pretreatment technique, theoretically belonging to chemical conversion film treatment. It is mainly applied to the phosphating of steel surfaces and can also be used for non-ferrous metal parts (such as aluminum, zinc). The primary purpose of phosphating is to provide protection to the base metal, to some extent preventing corrosion; it also serves as a primer before painting to enhance the adhesion and corrosion resistance of the paint film; and it plays a role in reducing friction and lubrication during metal cold working processes. Does the product need rust-proof treatment after phosphating?
Reasons for anti-rust:
Phosphatizing steel involves forming a thin layer of phosphate (such as iron, calcium, zinc, etc.) on the steel surface. This layer's rust prevention capability is quite limited. Therefore, phosphatizing is usually performed as an intermediate process in the workpiece processing, acting as a temporary rust prevention measure between operations.
After phosphatizing steel workpieces, it is essential to promptly apply further rust prevention or coating. Although the phosphatized surface requires drying and will not rust immediately, if left in a humid environment, acidic fluid will gradually seep out, leading to rust formation on the workpieces.
In response to the aforementioned issues, the following improvements can be made to steelwork:
1. In every process involving the use of process fluid, we have added a water washing step to ensure the cleanliness of the steel workpieces before each operation.
2. The current pickling solution is not effective in achieving complete rust removal. We recommend using Yongyu Brand environmentally-friendly rust remover, which can replace hydrochloric acid, nitric acid, sulfuric acid, and other pickling solutions for rust removal. A water-based product with organic acid substances, it produces no acid mist during the treatment process.
3. After phosphatizing, an anti-rust process should be added. The iron and steel workpieces can be immersed in "Yongyu" brand water-based anti-rust agent for surface anti-rust treatment. After the surface dries and cools, painting can be applied, or anti-rust packaging can be performed.
4. It is essential to test the compatibility of products used for degreasing, rust removal, and cleaning, as incompatibility between them can lead to mutual interference during use, resulting in diminished effectiveness and potentially causing corrosion on the surface of steel workpieces.
5. Recommend using verified compatible degreasing and rust remover: "Yongyu" brand rust preventive agent (YY-MGX-9031) or (YY-JGX-9041).
This is an analysis of the issue of rust returning after phosphatizing steel workpieces, along with some constructive suggestions. The specific techniques and methods should be adjusted according to the actual operational process, usage conditions, and properties of the workpieces. For similar issues requiring resolution, please contact Nantong Yongyu Antirust Material Co., Ltd., Tel: 0513-88832880/88832805.
