Research On Plasma Sprayed Basalt Coating And Its Performance

Plasma spray was used to spray many ceramic materials in order to obtain wear-resisting anti-corrosive coating, some mineral material such as slippery rock, sumire aoishi and so on can also be sprayed which form the special physical property amorphous material, but at present the research about basalt spray are still rare. In this study,basalt waste was used as main raw material.Two kinds of plasma spraying powder were prepared, and was used to obtain the coating on the surface of metal.The performances of the powder were evaluated by the indexes, such as particle morphology, particle size distribution. The composition ,appearance and structure of basalt coating were studied by optical microscopy(OM) scan electron microscope(SEM) and X-ray diffraction(XRD),in order to analyzes the coating structure formation process.The adhesive strength and corrosion resistance of coatings were tested,and the bonding and corrosion mechanism was studied. At last,a new idea of preparation of the inorganic non-metallic coatings on mental surface was explored.The research indicated that non-sintered basalt powder has many leng shape structures, the particle size distribute is quite wide, the fluidity is bad .The sintered power is more smoothly, the particle size distribution is quite centralized, and the fluidity has certain improvement, which can satisfies the plasma spray request. In the plasma spray process the sintered powder were melted quite full, easy to form the smooth coating surface appearance.The results show that non-sintering basalt powder has crystal structure,and its main minerals are pyroxene and plagioclase,its minor mineral is olivine.The organization and structure of the non-sintered basalt coating is mainly amorphous,containing a small amount of crystal minerals,such as magnetite,diopside,pyroxene,protoenstatite and so on.While the major structure of sintering powder is amorphous,containing a small amount of crystal structure minerals,such as ilmenite, anorthite,albite,olivine and so on.The structure of the sintered coating is mainly amorphous,it also contain a small amount of crystal minerals such as spinel,magnetite,corundum and so on .The basalt coating has typical layered and porous structure.It was found that there were less inadequate melting particles,internal pores and micro-cracks in coating made by the basalt powder which is produced by the method of sintering. The result of experiment shows that the coating and substrate were primarily combined by mechanical bonding ,and there are some holes and micro-cracks on interface of coating and metal surface.The adhesive strength of coating increased after sintering treatment of the basalt powder ,with a 5.83 MPa adhesive strength which increased by nearly 12.5%compared with the non- sintering basalt coating.The results of corrosion test show that the alkali corrosion resistance of basalt coating is superior to acid corrosion resistance,and the corrosion resistance of sinter-crushing treated coating was better than that of untreated coating .It can be concluded that natural basalt can be used to make thermal spray powders.With plasma spraying,a inorganic non-metallic coatings mainly having amorphous structure and great corrosion- resistance can be obtained.