| Phosphating technology is one of the most widely used surface treatment for steel nowadays. In coating projects, Zn-Phos is widely used because it prolongs the service life of the coating noticeably. But in the most phosphating technics, the higher phosphating temperature, sediment and waste oil caused economical loss, and the toxic fumes which the phosphating soluting send out is harm to human health. So developing room temperature energy-conservation, nonpoisonous and low pollution phosphating craft has already become the main research direction now.Under this background, In this disquisition Na2MoO4 has been chosen as the main accelerant of the phosphating solution through comparison of effect of different accelerant (KClO3, Na2MoO4 and SNBS); The phosphating solution includes the main film forming matter (H3PO4, ZnO), the main accelerant (Na2MoO4), the accessory accelerant (HNO3, Ni(NO3)2) and other additives (Emulsifier OP,Citric acid,NaF and Cu(NO3)2); And this disquisition educes the basic solution through orthogonal experiments. It is as follow: H3PO4: 30mL/L; ZnO: 15g/L; HNO3: 3.5mL/L; Emulsifier OP: 1mL/L; Na2MoO4: 3g/L; Ni(NO3)2: 4g/L; Citric acid: 1.0g/L; NaF: 1.0g/L; Cu(NO3)2: 0.05g/L.By analysing effect of single content (Na2MoO4, Ni(NO3)2, Citric acid, NaF and Cu(NO3)2) on corrosion resistance, effect of phosphating process and temperature, the best formula of the phosphating solution has been obtained. It is as follow: H3PO4: 30mL/L; ZnO: 15g/L; HNO3: 3.5mL/L; Emulsifier OP: 1mL/L; Na2MoO4: 3g/L; Ni(NO3)2: 4g/L; Citric acid: 1.5g/L; NaF: 1.0g/L; Cu(NO3)2: 0.05g/L; Temperature: 15～35℃; Time: 20min。In this disquisition the corrosion resistance of phosphate coatings and the weight of phosphate coatings has been studied. SEM, X-rays energy spectrum etc. physical detective means had been used to observe the microstructure and elements content. By means of the measurement of the polarization curve, the phosphate coatings performance has been studied. And the effect of ultrasonic phosphating has been studied in this disquisition. The result shows: The phosphate coatings is even and compact; The dropping test of CuSO4 is more than 130s; 3% of the NaC1 soaks for 3 hours there is no rusty spot appear; The coatings weight is 1.7～2.0g/m2; The microstructure is granule-shaped by means of SEM; The element of the phosphate coatings includes Fe, P, Zn and Mo etc. The life-span of this phosphate solution is calculated for 0.3m2/L tentatively; The sediment is 0.3g/L; testing of the adhesion of the coatings has been carried out. It offered the basis for popularization and application of the phosphating technology and supplied references for the room-temperature phosphate research.The effect of the single content of this phosphating solution on the phosphate coatings performance has been studied in this disquisition. |
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