Properties of coatings obtained by supersonic electric arc metallization with aerosol fluxing

Abstract

The method of electric arc metallization has both undeniable advantages and some disadvantages. For example, there is a burnout of alloying elements and a high content of oxides in the applied coating. Aerosol fluxing during metallization can solve this problem and neutralize the negative oxidative effect of interaction of the applied metal with air oxygen. This article discusses an effective method to improve physical and mechanical properties of an electrometallization coating using aerosol fluxing. The essence of this method is introduction of an aerosol together with compressed air into a torch of molten metal. This aerosol consists of an aqueous solution of the chemical inorganic materials. Such the aqueous solution is poured into a hydrodispergator, which is connected to the air channel of the metallizer. Aerosol fluxing makes it possible to deoxidize and ligate metal during electric arc metallization. As a result, the physical and mechanical properties of the metal increase. The paper considers the results of topographic studies of electrometallization coatings. Formed coatings have a structure with grain sizes from 200 to 2500 nm and also have pronounced and subtle grain boundaries. Aerosol fluxing with electric arc metallization forms a coating with finer-grained structure, which increases their strength. It is established that formed coatings have a finer-grained structure and increased strength when using aerosol fluxing during electric arc metallization. Metallographic studies showed that the thickness of the electrometallization coating varies from 2490 µm to 2586 µm. The use of aerosol fluxing during electric arc metallization does not significantly affect the coating thickness. The microhardness of electrometallization coatings was studied. This study showed that the use of aerosol flux consisting of Na2CO3 , Na3AlF6 , Na2B4O7 during metallization increases microhardness of electrometallization coatings by 1.6 – 1.9 times.

INVESTIGATION OF THE PROCESS OF ELECTRIC ARC METALIZATION OF COATINGS FROM STEEL 30KhGSA

“…The shape of the flattened metal particles allows us to conclude that at the moment of impact they were in a plastic state, in which they are easily deformed. In [15], the mechanism of coating formation during electric arc metallization was shown and it was found that large metal particles reach the surface mainly in the liquid state, while smaller ones in the plastic and even solid state. Liquid metal wets the surface and fills in irregularities, while colder (semi-liquid) metal particles are deformed upon impact and mixed with hotter ones, forming a single coating layer.…”

“…The resulting coatings are usually dense, uniform and have good adhesion to the substrate. They also have good resistance to wear, corrosion and high temperatures [3][4][5]. Coatings can be applied to improve the surface properties of a material for a variety of applications, including aerospace, automotive, and industrial applications [6][7][8].…”