Study On Preparation And Properties Of The Modified Basalt Powder And Its Coating Through Thermal Spraying

In this paper, the Zn-basalt compound powder which as feed for thermal spraying areprepared by Zn and raw basalt after modification polymerization granulation, and use it tomanufacture corrosion resistant coating on the surface of45#steel substrate. Optimumparameters of flame spraying of basalt coating is discussed; using infrared absorptionspectroscopy and X-ray diffraction to analyze the structure of powder and coatingrespectively, the morphology of the powder and coating are observed by scanning electronmicroscopy; the properties of thermal and fluid and particle size distribution of the powder arestudied; what is more, the properties of microscopic hardness, porosity, bonding strength andcorrosion resistance of coating are also studied.The results of research for powder show that be modified by add20%Na2O in basalt, thestructure of basalt after modified is changed crystalline structure into an amorphous structure, The structure of Zinc-basalt compound powder is made by basalt of amorphous structure andZinc of crystalline structure. The particle size of Zinc-basalt compound powder is mainlydistributed in49-75microns, as high as95%above; the distribution of particle size of basaltpowder is wide, the particle size is uniform and fine powder, powder under49micronsreached15%. Zinc-basalt compound powder, the shape of the particles has greatly improved,tend to more be spherical powder. Compared with raw basalt powder and amorphous basaltpowder, fill density and flow rate of Zinc-basalt compound powder are increased obviously.The results of research for coating show that the best process parameters of flamespraying for basalt coating is that preheat number10times, the powder flow20g/min,spraying speed30cm/s, oxygen pressure0.43MPa, acetylene pressure0.09MPa, sprayingdistance12cm, spraying number10times, the thickness of coating is290microns. Thestructure of basalt coating and Zinc-basalt composite coating are consistent with the structureof their powders. With the increase of adding amount of Zinc, the porosity of Zinc-basaltcomposite coating is more and more small, the bonding strength of Zinc-basalt compositecoating is more and more high, the microhardness of coating also will increase. Basalt coatinghave a good protection effect for the steel substrate，the Zinc in the Zinc-basalt compositecoating has the role of cathodic protection in the metal corrosion, the Zinc-basalt compositecoating could priority to participate in corrosion, and corrosion products of the Zinc can blockpore, block matrix corrosion to occur in the contact with the environment.