Reactive flame spraying of TiC–Fe cermet coating using asphalt as a carbonaceous precursor

Abstract

In this paper, a kind of Ti–Fe–C compound powder for reactive flame spray (RFS), using ferrotitanium and asphalt as raw materials, was prepared. The main feature of the process was that asphalt, as a carbonaceous precursor, is used as the origin of carbon. The agglomerated Ti–Fe–C compound spraying powder was prepared by heating a mixture of ferrotitanium and asphalt to pyrolyze the asphalt. The carbon by the pyrolysis of the asphalt was a reactive constituent as well as a binder in the compound powders. TiC/Fe cermet coating was prepared by RFS of the compound powder. XRD and SEM were employed to analyze the phase composition and microstructure of the compound powder and coating. The hardness and wear resistance of the coatings were tested. The results show that: The Ti–Fe–C compound powder has a very tight structure, which can avoid the problem that reactive constituent particles are separated during spraying. The TiC–Fe cermet coating by RFS presents typical morphology of thermal spraying coating with two different laminated layers: one is the composite reinforcement layer in which the round fine TiC particles are dispersed within the α-Fe matrix, the other is the layer of TiC accumulation. The TiC/Fe cermet coating by RFS shows high hardness and wear resistance property: the surface hardness of the TiC/Fe cermet coating is 65 + 6(HR30N). In the same fretting conditions, the wear area of Ni60 coating is much more than that of the TiC/Fe cermet coating.