Microstructure and mechanical properties of the Mo-NiCrBSi coating deposited by atmospheric plasma spraying

Abstract

Prah koji je korišćen u ovom istraživanju (Mo-NiCrBSi) je mešavina dva praha, praha Mo i praha 'samotekuće' legure NiCrBSi, u procentualnom odnosu 75/25%. Nanošenjem ove mešavine prahova dobijena je 'samotekuća' prevlaka na bazi molibdena. Prevlaka je naneta plazma sprej postupkom u atmosferskim uslovima. Kvalitet ovako dobijene prevlake zavisi od nekoliko parametara kao što su: veličina čestica praha koji se nanosi, temperatura nanošenja, vrsta gasova koji se koriste, količina unetog praha, ugao i tempo nanošenja (kontinualno ili sa prekidima), rastojanje plazma sprej pištolja od osnove, temperatura osnove, primenjeni pritisak tokom postupka itd. Sve ove parametre treba pažljivo izabrati kako bi se dobile prevlake sa najboljim karakteristikama, a u zavisnosti od željene primene. U ovom istraživanju su korišćene tri grupe Mo-NiCrBSi prevlaka dobijene sa tri različita rastojanja plazma sprej pištolja od osnove. Mikrostrukture i mehaničke karakteristike dobijenih prevlaka su analizirane da bi se došlo do optimalnih parametara nanošenja tj. do onih koji daju najbolje rezultate.

The powder used in this research (Mo-NiCrBSi) was a blend of powders composed of 75% Mo and 25% self-fluxing alloy NiCrBSi. With the deposition of this powder a molybdenum base self-fluxing coating is obtained. The process used for coating deposition was atmospheric plasma spraying (APS). The quality of the coatings deposited by APS depends on several parameters such as the sprayed particle size, the deposition temperature, the combustion gases, the feed speed, the angle and rate of deposition (continuous or intermittent), the spray distance, the temperature of the substrate, the pressure applied during the process, etc. All these parameters should be carefully selected in order to obtain the best coating properties for each application. In this research, three groups of the Mo-NiCrBSi coating specimens were produced with different spray distance parameter. Their microstructure and mechanical properties were analyzed in order to find the optimal spray parameters i.e the ones that give the best structural and mechanical characteristics of the coating.