Journal of Nanomedicine & Nanotechnology

Effect of silica as flow enhancing additive on AM processability and build of gas atomized IN718 alloy powder

7^th International Conference on MATERIALS SCIENCE AND NANOTECHNOLOGY

December 05-06, 2022 | Dubai, UAE

Joseph Oluleke

Carpenter Additive, United Kingdom

Posters & Accepted Abstracts: J Nanomed Nanotechnol

Abstract:

Metal powder flowability is a key attribute necessary for efficient and optimum processability on most metal additive manufacturing (AM) machines. Quite often, some metal powders may be rejected simply because they do not flow through or meet the expected flow rate on “Hall” or “Carney” flowmeter, even though other important material characteristics, notably chemistry, morphology, particle size distribution (PSD) and apparent density, may have been met. Based on the concept of reduced interparticle friction and van der Waals forces, one method of enhancing metal powder flowability, and thereby reducing rejection rate, is the use of flow additives. In this work nonflowing gas atomised IN718 powders have been doped with nano-sized silica at varied concentration to enhance their flowability. This has led within a limit to a reduced Basic Flowability Energy (BFE) value, as measured on the Freeman FT4 Powder Rheometer, when compared to virgin un-dosed powders of equivalent chemistry, morphology, moisture content and PSD. It was however found that increasing the doping concentration beyond a certain limit much higher than 30 ppm gradually retards powder flowability. Despite the above-mentioned success of improved flowability, very little is known regarding the impact of using nano-sized silica on the processability and metallurgical performance of the resulting AM build parts. The intention of this work is to present the results of systematic studies on doped gas atomised IN718 powder and corresponding AM build coupons which subsequently have been characterised with extreme high-resolution SEM, TEM and XRF for quantification. Further assessment of the metallurgical performance of the AM builds test coupons have included tensile, fatigue, hardness testing and fractography. Within experimental error for the doping concentrations under consideration in the project, it was found that the silica addition poses no detrimental effect on the mechanical properties of the resulting AM build when tested at room and elevated temperature. It is therefore anticipated that the insight gained from these studies would encourage the use of flow additives, thereby reducing the number of flow related rejections and as a result maximising the potential use of atomised powders.