In this work, near-net-shape powder metallurgy hot isostatic pressing (NNS PM HIP) of Ni-base metal matrix composite (Ni-MMC) was developed to improve the hardness and wear properties of turbopumps mechanical seals. Silicon carbide (SiC) and titanium diboride (TiB2) fine powders were used as reinforcements with different ratios to improve the hardness and consequently the tribological properties of the developed Ni-MMC material. Powder characterisation was performed on the blended powders to check the homogeneity of the mixed powders. The hot isostatically pressed (HIPed) Ni-MMC microstructures were analysed using scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) techniques. The HIPed material showed a fully dense microstructure with a continuous network of ceramic reinforcement particles at the prior particle boundaries (PPBs). Furthermore, microhardness tests were performed on IN625, IN625-SiC and IN625-TiB2 to understand the impact of the reinforcement on the microhardness. It was demonstrated that the volume percentage of ceramic reinforcement in the IN625 matrix plays a crucial role in achieving higher hardness by increasing the fraction of hard phases appearing in the microstructure of the developed Ni-MMC material. The final part of the work focuses on the canister design and manufacture of a near-net-shape (NNS) mechanical gas seal using IN625 based MMC to demonstrate the feasibility of manufacturing mechanical seals through the NNS PM HIP technique. Overall, IN625 based MMCs resulted in a drastic improvement in tribological properties if compared to the base material. Furthermore, the employment of the PM HIP consolidation technique resulted in a fully dense and homogeneous microstructure, highlighting the potentials of PM HIP in the generation of novel composite materials.
Bibliographical noteFunding Information:
The authors warmly thank the European Space Agency (ESA) for supporting this activity in the frame of the General Studies Technology Programme (ESA GSTP ITT 8899) under contract 4000122901/18/NL/BJ. AS acknowledges the Centre of Doctoral Training in Innovative Metal Processing (IMPaCT), funded by the Engineering and Physical Sciences Research Council (EPSRC); grant EP/L016206/1. The work was enabled through the National Structural Integrity Research Centre (NSIRC).
- IN625-Metal Matrix Composites (MMCs)
- Mechanical properties
- Near-net-shape powder metallurgy hot isostatic pressing (NNS PM HIP)
- Tribological properties
ASJC Scopus subject areas
- Chemical Engineering(all)
- Mechanics of Materials