| Steel reinforced polyethylene spiral corrugated pipe is widely used in urban underground construction,which is made of steel skeleton and coated with polyethylene on both sides.The adhesion between steel and polyethylene is of great significance to the improvement of its service life.The effect of surface treatment on the adhesion of steel matrix to grafted polyethylene was studied.After hot-dip Zn-Al alloy coating and passivation treatment,Al element in the alloy participates in chemical reaction to improve the adhesion between the coating and the grafted polyethylene.Compared with the adhesion between Zn layer and polyethylene,the adhesion of hot-dip Zn-Al was increased by 84.6 % without passivation treatment,and by 133.1 %after passivation treatment.The silane coupling agent in the passivator reacts on the surface of the coating to form chemical bond and improve the bonding property.After passivation,the adhesion of Zn,Zn-Al,Zn-Al-Mg with polyethylene were increased by 73.3 %,26.6 %,and 33.3 %,respectively,compared with those before passivation.Phosphating treatment increases roughness and the contact area between the matrix and the grafted polyethylene.On the other hand,the "hook-up" effect of crystalline phosphating film on polyethylene to improve the adhesion.The adhesion reached the highest adhesion of324.8 N at 5min of phosphating,which was 204.7 % higher than that of hot dip galvanizing.The residual compressive stress on the surface of the matrix was produced by shot blasting,and the compressive stress increased with the shot blasting time.The surface roughness is the main factor that affect the adhesion between the matrix and the grafted polyethylene.The highest adhesion reached 170.3 N at 8 min shot blasting,which was 59.8 %higher than that of hot dip galvanizing.The results show that passivated Zn-Al coating,phosphating treatment and shot blasting treatment can improve the service life of steel strip in steel strip reinforced polyethylene spiral corrugated pipe. |
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