For metal surface coated castings, the surface treatment methods we commonly use include mechanical polishing, chemical treatment, surface heat treatment, spraying surface, etc. The surface treatment is to clean, clean, deburr, remove oil stain, and scale the workpiece surface. The surface treatment of metal is also particularly important in the coating process, which is related to the quality and effect of spraying.
1、 The importance of pretreatment of metal coating
For metal anti-corrosion coatings, there are many factors that affect the coating performance, such as coating composition, coating form, substrate surface pretreatment, coating structure, coating method, coating quality monitoring and coating post-treatment.
Generally, the causes of coating failure can be divided into four categories:
(1) Improper selection of coating system accounts for 20%;
(2) Poor substrate surface treatment accounts for 40%;
(3) Insufficient or uneven coating thickness accounts for 20%;
(4) Unreasonable coating management and process account for 20%.
This shows the importance of metal surface treatment.
2、 Purpose of metal substrate pretreatment
(1) Enhance the bonding strength (adhesion) between the coating (paint film) and the metal surface of the object to be coated. The pretreatment methods include: mechanical roughening, chemical reaction film formation, chemical (physical) adsorption, preparation of transition layer and combination effect;
(2) Improve the protective (anti-corrosion) performance of the coating on the substrate, such as coating steel parts after galvanizing;
(3) Create good conditions for the smoothness (fullness) of the coating, improve the appearance and decoration of the coating, such as puttying.
關閉返回