Abrasive wear behaviour of Ni(Cr)–TiB2 coatings deposited by HVOF spraying of SHS-derived cermet powders

Self-propagating high-temperature synthesis of ZrB2 or TiB2 reinforced Ni–Al composite powder

“…The hardness of the reinforced samples increases with the amount of ZrB 2 and reaches 812 ± 94 HV 0.2 for the 40 wt.% ZrB 2 sample, while the hardness of the 40 wt.% TiB 2 sample is about 967 ± 104 HV 0.2 . The above values are comparable with the hardness of IMCs produced via SHS in other studies [10,17,21]. The hardness of the samples confirms the suitability of these powders for hard coatings.…”

“…As observed by other authors on the SHS of TiB 2 in presence of Ni, the formation of the boride particles inside the metallic matrix occurs as the concentration of Zr or Ti and B exceeds the saturation limit either as an effect of the increased amount of atom dissolved or of the temperature lowering after the passage of the reaction front [17]. This ultimately leads to the formation of boride particles embedded in the NiAl matrix, as seen in Fig.…”

“…Milling and sieving can easily lead to a much better control of the particle size distribution. What is on the other hand important, in view of the possible thermal spray application of the IMC powder, is the mutual dispersion of the two phases [17][18][19]. Microstructural examination of the phase distribution inside the IMC powder was performed on samples which were cold pressed, sintered at 1500 • C for 6 h under argon atmosphere and then polished using standard metallographic techniques.…”

“…The above properties have been also exploited in the case of IMCs deposited as protective coatings for thermal or oxidation barrier applications [17][18][19]. Thermal spray techniques were proven to be particularly suitable for the deposition of NiAl based IMCs [20].…”

“…Together with low energy requirements and short reaction times, SHS was, in fact, shown to produce IMC powder with excellent bonding between the reinforcements and the matrix components, as a result of the in situ formation of these phases at high-temperature [23]. Thus, powders produced by SHS are attractive for thermal spray coatings [17][18][19]23]. …”