PVD TiN and CrN coated austempered ductile iron: analysis of the influence of processing parameters on the coating characteristics and the substrate microstructure

D.A. COLOMBO; M.D. ECHEVERRÍA; O.J. MONCADA; J.M. MASSONE

ISIJ INTERNATIONAL

IRON STEEL INST JAPAN KEIDANREN KAIKAN

Lugar: Tokio; Año: 2012 vol. 52 p. 121 - 126

0915-1559

This work studies the influence of the PVD processing parameters on the characteristics of TiN and CrNcoatings deposited on ADI substrates, austempered at 360°C, with different nodule counts and surfaceroughnesses. Coatings were applied by arc ion plating using an industrial reactor and different sets ofparameters, with BIAS voltages, arc currents, chamber pressures and substrate temperatures varying from?100 to ?250 V, 60 to 65 A, 0.7 to 2.8 Pa and 280 to 450°C, respectively. The effect of the different depositionsconditions on the substrates microstructure was also analyzed. The existing phases, preferred orientation,surface topography, film thickness, hardness and adhesion of each coating were determined.The retained austenite content and hardness of each substrate were computed before and after coatingdeposition.The results obtained indicate that the different deposition conditions and coating materials evaluated donot generate significant changes neither in the resulting topography nor in the coating adhesion, whichcan be related to indices between HF1 and HF2. Coating adhesion was not affected by different substrateroughnesses. The combined reduction of BIAS voltage, arc current and chamber pressure leads to adecrease of TiN growth rate and hardness, while high substrate temperatures promotes an increase in TiNand CrN growth rates. Substrate temperatures around 300°C with deposition times of up to 240 min donot promote noticeable changes on the ausferritic microstructure, while temperatures of 400°C and abovetranslate into a clear microstructural deterioration, even for short deposition times.