Increase of the pressure of air flow from 0.6 to 1.2 MPa provides the growth of its speed from 300 to 600 m/s. The increase of air flow speed reduces the flight time of drop from the arc to the substrate and them against the prepared surface at higher temperatures. Increase of the pressure of air provides reduction the size of drops and oxides between lamellas as well as improves the mechanical characteristics.

Development of new arc sprayed iron based coatings for protection against gas abrasive wear at room and elevated temperatures are of the great interest because of permanently increasing pressure to reduce production and repair costs of power production facilities. Two cored wires in steel cover with Fe-Cr-B-Al and Fe-Cr-N-Al filling are proposed as an alternative choice for self fluxing and cermet coatings that are considered nowadays for protection of screen tubes of boilers of power stations that are operated under the temperatures 500-600 °C. Oxidation behaviour of arc sprayed coatings is estimated by gravimetric measurements. Abrasive wear resistance at elevated temperatures after 1 hour is investigated by means of laboratory unit that alloys a rotation of coated specimens in heated quartz sand. It is shown that abrasion wear lost of carbon steel increases 1.5 times when test temperature increases from 20 °C to 550 °C. For all investigated coatings the 20-25% decrease of wear lost is observed at higher temperature. Arc sprayed coatings of both investigated systems improve significally the abrasive wear resistance of carbon steel. At room temperature the improvement by factor 1.3-2.2 times and at the temperature 550 °C by factor 2.7-4.6 is observed depending on chemical composition of coatings.

Different post treatment methods such as heat treatment, mechanical processing, sealing, etc. are known to be capable to improve microstructure and exploitation properties of thermal spray coatings. In this work a plasma electrolytic oxidation of aluminium coatings obtained by arc spraying on aluminium and carbon steel substrates is carried out. Microstructure and properties of oxidised layers formed on sprayed coating as well as on bulk material are investigated. Oxidation is performed in electrolyte containing KOH and liquid glass under different process parameters. It is shown that thick uniform oxidised layers can be formed on arc sprayed aluminium coatings as well as on solid material. Distribution of alloying elements and phase composition of obtained layers are investigated. A significant improvement of wear resistance of treated layers in two types of abrasive wear conditions is observed.

This paper presents the results of a study on arc-sprayed coatings made from powder-cored wire. The wires used consist of a ferrochromium core with additions of boron, aluminum, and carbon compacted in a steel sheath. The coatings are sprayed using a modified burner operated at 34 V and 140 A with an air jet pressure of 0.6 MPa. During spraying, specimens are rotated at a speed of 60 rpm. XRD analysis is used to examine the initial phase composition of the layers as well as friction-induced changes in the subsurface resulting from block-on-ring wear tests. Cross-sectional examination shows that the coatings have low porosity (∼10%) and small grain size (50 to 150 µm). Based on these findings, it is concluded that the wear resistance of wire arc sprayed coatings is largely determined by powder wire composition, initial coating structure, and the structural stability of the subsurface layer. Paper includes a German-language abstract.