Public-Funded Projects
Our public-funded projects see our experts work in partnership with others from industry and academia, typically to solve a particular challenge. These projects will often revolve around a specific industry sector although the findings may also provide useful for a range of other industries too. Example projects that investigated PM HIP include…
- TWI Pioneers New Dissimilar Weld for European Space Agency
The combustion chamber is the hottest part of a rocket’s engine and the higher the temperature, the more efficiently it can perform. This means that there is a desire to increase the chamber’s operating temperature through the use of highly heat-resistant materials. C103, which is an alloy of niobium with hafnium, has been used with R512E di-silicide coating for chamber temperatures up to ~1350°C. However, ceramic material such as silicon nitride (Si3N4) is able to withstand heats of around 1500°C and higher, making it particularly suitable for rocket combustion chambers. However, ESA wanted to join this ceramic with C103 to avoid the challenge of manufacturing monolithic ceramic combustion chambers. Although this had never been achieved before, early tests at TWI demonstrated a solution to this challenge, successfully joining C103 alloy with silicon nitride for the first time in our history, using diffusion bonding and vacuum brazing processes with the aid of interlayers. The joining of these dissimilar materials was demonstrated in the form of rings that are representative of thruster combustion chamber joint geometry (Figures 2-3).
- GEO-COAT Project: PM HIP metal matrix composites (MMCs)
As part of the Geo-Coat (Development of Novel and Cost-Effective Corrosion Resistant Coatings for High Temperature Geothermal Applications) project, TWI undertook a microstructural characterisation of Inconel625 (IN625) and Ti-6Al-4V (Ti64) base metal matrix composites (MMCs) consolidated using uniaxial hot pressing (UHP) and hot isostatic pressing (HIP). MMC powders were mixed with different amounts of ceramic particles before being consolidated by UHP and HIP processes. The microstructures were then characterised using scanning electron microscopy (SEM) and X-ray diffraction (XRD) while the hardness and impact toughness were assessed using Vickers microhardness and Charpy impact testing, respectively, and the rate of erosion was obtained using erosion-corrosion test results. The main objective of this work was to further characterise the PM base MMCs to evaluate their microstructure, tribological, and mechanical properties (Figure 4).
- Powder Metallurgy for Astrospace Applications
TWI partnered with Airbus Defence and Space, Nammo Westcott Ltd, ESR Technology and the University of Birmingham for a project to investigate the use of powder metallurgy (PM) for astrospace applications. The 24-month project, ‘Powder Metallurgy Based Materials for High Wear Resistance, High Hardness and High Temperature,’ aimed to develop systems to provide more efficient equipment for use by the next generation of spacecraft during launch and through longer in-orbit missions. TWI, working alongside the University of Birmingham, developed and tested suitable PM-based materials for high wear resistance, high hardness and high temperature use. The use of powder metallurgy allowed for complex shapes to be produced without extensive machining and with a reduction in material wastage. The PM process also avoids the possibility of small imperfections from a machining process leading to failure of the final product, while the fine grain structure of PM-produced parts often leads to an enhancement of material strength when compared to conventional processes. Powder metallurgy should also provide cost-saving solutions with a shorter lead time as well as offering the opportunity to produce graded materials with a variety of properties, such as a softer core surrounded by a harder surface. The results of this research were later published in the peer-reviewed journal, ‘Advanced Powder Technology,’ with the title, 'Development of Ni-base metal matrix composites by powder metallurgy hot isostatic pressing for space applications’ (Figure 5).
- Near Net Shape Powder Metallurgy Hot Isostatic Pressing
The European funded H2020 SUPREME (Sustainable and flexible powder metallurgy processes optimisation by a holistic reduction of raw material resources and energy consumption) project investigated the use of advanced manufacturing processes to improve manufacturing process efficiency and reduce material wastage. This work drew upon TWI’s experience to produce an efficient manufacturing process for fabricating Y-shaped Inconel 625 (IN625) submarine pipe using NNS PM HIP manufacturing technique. This study focused on understanding the influence of IN625 powder atomisation route and powder characteristics on the microstructure and mechanical properties of HIP’d material fabricated using four different powders, including argon gas atomised (AGA), nitrogen gas atomised (NGA), plasma atomised (PA) and water atomised (WA) powders. All four powders were characterised, including chemical analysis, physical properties (apparent and tap density and flowability), powder morphology and particle size distribution (PSD) (Figure 6). The microstructure of four HIP’d powders is shown in Figure 7. The results of as-HIP’d tensile properties confirmed that PA powder possessed the best balance between strength and elongation, with superior properties if compared to the minimum specification of wrought IN625 (Figure 8). With PA chosen as the favoured powder for the application, we designed a capsule (Figure 9) and produced prototype pipes (Figure 10) that showed good geometrical accuracy with a reduced buy-to-fly ratio of 2:1, which is more than 3.5 times lower if compared to the conventional manufacturing process.
- TWI Specialists Assist with Fusion Energy Advancements
This UKAEA-funded project saw TWI work alongside Frazer-Nash Consultancy to develop pure tungsten and tungsten carbide shielding components for a manufacturing demonstrator in support of the design and construction of a prototype fusion energy plant in Nottinghamshire, UK. Hot isostatic pressing diffusion bonding (HIP DB) was chosen as a viable route to join the demonstrator segments, which led to HIP DB trials to down-select the correct interlayers for the materials to be joined as well as the joining process parameters. The project work then shifted its attention towards HIP canisters design and fabrication to manufacture large demonstrator parts that involved the joining of W and WC blocks with a stainless-steel cooling channel (Figure 11).
Dedicated Industrial Member Support and Other Projects
Many of the largest and best-known companies from across all industry sectors have called upon TWI’s PM HIP expertise for their own needs. Conducted for our Industrial Members independently and impartially, these projects are necessarily confidential in nature, so we are unable to offer exact details here.
However, to find out more about PM HIP at TWI, please visit our dedicated webpage, here: https://www.twi-global.com/what-we-do/services-and-support/powder-metallurgy-hot-isostatic-pressing