The results of investigations of the hardness and wear resistance of the working sections of machines, hardened using cermet materials in the form of paste, are presented. The optimum composition of the paste which greatly increases the service life of the working sections of the machines is determined.In the cultivation and the service of machines, the working sections are subjected to rapid wear as a result of the effect of abrasive particles, the cutting surfaces are blunted, and the shape, profile and working dimensions are greatly changed. Consequently, the quality of field operations is disrupted, the performance of these operations is delayed, the idle time of equipment is extended, the consumption of fuel and lubrication materials is increased and the amount of finished products is decreased [1 -3]. Therefore, the development and application of technologies capable of increasing the wear resistance of the working sections of machines is an important task and the solution of this task is of considerable importance in many areas of production.At present, a promising hardening method, which greatly increases the hardness and wear resistance of the cutting edges of the working sections of the machines, is vibroarc hardening (VAH) with cermet materials [4 -6]. In VAH, a cermet material in the form of paste is deposited on the hardened surface of the working section and burning of the direct arc results in both thermal diffusion hardening of the surface with alloying elements, including the composition of the cermet material, and VAH of the cermet coatings. A distinguishing feature of VAH is the absence of any significant heat input into the component during hardening.The cermet material developed in this study consists of a steel matrix (surfacing powder) with inclusions of alumina Al 2 O 3 , silicon SiO 3 , boron carbide B 4 C, refined to the nanosized state, and also alloying elements: nitrogen, present in the ammonium nitrate NH 4 NO 3 , and aluminium [5 -7]. Aluminium is used for deoxidation of iron and also for the formation of the ceramic phase by transformation to the aluminium oxide Al 2 O 3 and, in subsequent melting, to corundum. Corundum occupies position 9 in the mineralogical table of hardness, which is very close to the hardness of diamond. The matrix is an impact resistant, sustaining and composite frame of the cermet material. Therefore, the matrix material is produced from steelsurfacing powders with high hardness and abrasive resistance, for example PG-10N-01, PR-N70Kh17S3R4 and PG-SR4. To ensure the high impact toughness of the hardened surfaces, the content of the matrix material in the composition of the cermet material should not be less than 50%.Preliminary investigation showed that each of the components of the cermet material has a strong effect on the efficiency of hardening of the working sections of the machines. Therefore, investigations were carried out to determine the effect of the components of the cermet material on the hardness and wear resistance of hardened surfaces in orde...
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.
The article presents the results of studies of the effect of flux components on the adhesive strength, porosity and oil absorption of coatings obtained by supersonic arc metallization (EM) using aerosol fluxing (AF) deposited on 45G2 steel with a speed v = 400-410 m / s. Due to the use of AF in EM, the adhesion strength of electrometallization coatings (EM coatings) increases. The highest value of adhesive strength is 66 MPa. Porosity due to the use of AF decreases by 1.5 - 1.6 times, in comparison with EM coatings without AF. At the same time, the oil absorption of EM coatings using AF decreases 1.6–1.7 times. It is advisable to use EM coatings with AF when restoring worn-out parts for various purpose equipment, as well as for eliminating defects at the production stage.
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