The investigation iron-based cored wires for thermal arc spraying

Abstract

This paper presents new experimental created iron-based cored wires, for thermal arc spraying, doped with Mn-Cr-Mo-Ni-Mn-Cr-Mo, Mn-Cr system alloying elements, which exhibit exceptional tribological properties of coatings determining the good performance. The main task was to identify the main technological parameters of the spraying parameters and properties of the coatings. Experimental investigation methods were applied for evaluating the thermal arc spraying coatings obtained by the qualitative characteristics in the present research. Tribological properties of coatings were evaluated in accordance with ASTG 65 – 04, ASTMG 75 – 07 standards. Also coatings were evaluated according to sliding wear test. The corrosion properties of coatings were investigated by potentiometric dynamic corrosion tests. Thermal sprayed metallic coatings are extensively used in different branches of engineering to protect the surface of components from wear, corrosion or to restore thickness of details. Thermal spray techniques are grouped according to the type of energy use. One of them is electric arc spraying. In the electric arc spray process (also known as the wire arc process) two consumable wire electrodes connected to a high – current direct-current (dc) power source are fed into the gun and meet, establishing a arc between them that melts the tips of the wires. The molten metal is then atomized and propelled toward the substrate by a stream of air. The process is energy efficient because all input energy is used to melt the metal. The electric arc spraying is the low-cost process with high productivity regarding the preservation of the quality of sprayed layers. Spray rates are driven primarily by operating current and vary as a function of both melting point and conductivity. Electric arc spraying also can be carried out using inert gases or in a controlled – atmosphere chamber. Temperatures within the arc rise to 6500 ºC. High temperature at the wire ends can cause a burning loss of alloying elements in the spray materials. For elements such as silicon or manganese, loss can rise to 40 %, for other elements, e.g. carbon, even up to 50 %. Adapted alloyed bulk or filled wires are therefore necessary. Thermal sprayed metallic coatings are highly capable of improving the superficial wear resistance of industrial components. Wire filler materials, the specific processes and parameters predominantly influence the characteristics and hence the properties of the sprayed coatings. The filler material of wires can be vary various. Usually wires for thermal arc spraying has chromium content ranging from 1 to 5%. That choice was determined by the relatively small cost of wires and good mechanical properties of coatings.