Exploiting graphene and nanodiamond to enhance wear resistance of carbide-based materials by Spark Plasma Sintering
Start date: 1 October 2019
The focus of this project is to explore a bottom-up strategy to design nanodiamond, graphene and tungsten carbide ceramic composite materials.
This project emerges from our work in the multidisciplinary Cardiff Materials Research Network collaborative teams. The student’s research will mainly take place at the new Materials Processing Laboratory in the School of Engineering at Cardiff University, using the new RIF-funded Spark Plasma Sintering system. The project will involve interaction with other PhD students and the Cardiff Diamond Foundry. The successful candidate will also interact with the EPSRC Centre for Doctoral Training in Diamond Science and Technology, Warwick University, UK.
Structural ceramics and their composites play an essential role in engineering (ie aircraft brakes, drilling machinery, cutting tools, bearings etc). There is a need to find sustainable manufacturing processes to avoid climate change and at the same time ensure the performance and longevity of materials. This is exceptionally challenging, but advanced composites engineering can play an important role. Exploring ways of combining the right materials using environmentally friendly processing and manufacturing technologies has proven to be the pathway to follow.
Tungsten carbide-cobalt (WC-Co) ceramic composite’s wear and corrosion resistance have been enhanced, typically by tuning Co content and incorporating high hardness phases such as ZrO2, B4C particles, and graphite or other free-carbon sources to compensate for W dissolution into the cobalt binder. Most recently nanodiamond particles have been used to improve both. In addition, novel rapid consolidation techniques such as Spark Plasma Sintering have played an important role in achieving full density and restricting grain growth. However, despite using advanced sintering which can maximise properties by retaining grain size, the previous processing steps have not been engineered enough to exploit the advantages of the second phase and typically simple mixing is the chosen route. Recently we have made bioinspired self-monitoring ceramics by using graphene networks (Rocha et al. Nature Comm, 2017). This strategy of using graphene networks to design layered ceramic composites with improved toughness and electrical conductivity can now be applied to build nanodiamond–graphene networks, which in turn could host a WC-Co matrix.
Project aims and methods
You will study graphene oxide suspension processing in order to build 3D graphene networks, which in turn will serve as scaffolds to host nanodiamond particles and ceramic-based materials. Wet chemistry processing, freeze casting and Spark Plasma Sintering will be married to achieve the goal. The challenge is to design, build up, and evaluate new composites with enhanced hardness and fracture toughness combined with excellent wear behaviour. Property-process-microstructure relationships will be used to drive a deeper understanding of behaviour and failure mechanisms in order to maximise performance.
In this project a vast variety of skills and techniques will be developed and used. The first stage of the project will deal with characterization and processing of materials and different techniques such as particle size distribution, zeta potential, XRD, SEM, TEM among others will be used. Skills in wet processing of graphene and ceramics together with their shaping by freeze casting will also be acquired and thus fundamental learning in rheology will be developed. Finally, the achievement of the novel composite will also demand training in mechanical testing, particularly in wear, and electrical characterization. We will collaborate with the Centre of Advanced Structural Ceramics at Imperial College London, Queen Mary University London and collaborations with a graphene supplier “GRAPHENEA” and with KENNAMETAL may also arise. Moreover, across college collaborations may be also possible due to the multidisciplinary character of the research proposed. For instance, Professor Oliver Williams will bring his experience in the synthesis and characterization of nanodiamond particles. His experience will help us to refine our processing and sintering methods.
The ground-breaking materials and methods for material fabrication that will be developed within the scope and throughout the duration of this project will definitely contribute to the continuation of the UK’s industrial competitiveness.
Professor Oliver Williams