High-temperature wear behaviour of borided Inconel 718 HVOF coatings

Abstract

Abstract Increasing demands on component performance and efficiency require continuous development efforts in existing material systems and concepts. In addition to the specific material properties, economic aspects have to be taken into account. Thermochemical treatments of iron-and nickel-base alloys allow for a distinct improvement of hardness and wear resistance. The process of boriding enables the highest hardness values and the formation of thermally stable precipitates. Especially nickel-base alloys are suitable for high temperature applications. An economic application of these alloys can be achieved by applying coating technologies and limiting the material usage to the surface. High-velocity oxygen fuel thermal spraying of the nickel-base alloy Inconel 718 and subsequent powder-pack boriding is conducted. Furthermore, the influence of a solution annealing step prior to the boriding process is investigated with the motivation to achieve a homogenisation of the coating. A successful diffusion enrichment and the formation of a precipitation layer could be achieved. The investigation of the resulting properties revealed a distinct increase of hardness and an improvement of wear resistance tested under reciprocating conditions in a wide temperature range.