Silicon doped boron carbide a lightweight impact resistant material

Lead Research Organisation: Imperial College London
Department Name: Materials


There is a need for impact resistance light weight materials for a number of applications including, 1) for the aerospace industry, particularly satellites where protection from high speed space debris is required 2) ballistic personal armour. In this case, high quality light weight armour is essential to protect soldiers and to allow them function efficiently. In both cases high velocity impacts occur and weight is crucial. Boron carbide has the potential to be an excellent material as it is very hard and very light; however it unexpectedly fragments under shock or high pressure loading. We have shown in preliminary work that by carefully adjusting the chemistry of the material with small additions of Silicon the mechanism of fragmentation under high pressure loading is suppressed, although it is unclear if this translates to improved impact performance.
Therefore in this work we aim to study in detail the mechanism by which boron carbide deforms and how this is altered by small additions of Silicon. This will involve deforming the materials within a high resolution electron microscope to understand which parts of the materials fail first and how. In parallel to these experiments, high velocity gas gun experiments on larger samples will help us understand how the deformation moves through the material, this is particularly important in impact resistant materials. Among other things this will require considerable improvements in our ceramic processing knowledge to produce the large amounts of the silicon stabilized boron carbide particularly for the gas gun experiments. However, if successful this knowledge will directly relevant to our industrial partners who will be able to quickly exploit it. The cutting edge analysis that will be required for this project will rely of devolvement of analytical techniques that can be applied in the future to a range of other materials. This includes high speed spectroscopic diagnostic tools which do not exist in the country at this time.

Planned Impact

Demonstrating that by doping boron carbide with Si it is possible to create a low density ceramic with a hugoniot elastic limit above 40 GPa would have a large impact on a number of fields. It would open a range of aerospace applications including whipple shields for satellites and other vehicles. It would also be directly applicable for ballistic armour, where particularly for personal armour weight is crucial. The state of the art body armour systems worn by western soldiers weights around 12 kg and is a combination of ceramic plates and polymer fibres where the ceramic is the main component. There is a huge driver to reduce this by 50% along with other pieces of equipment, to reduce injury (simply from the weight) and improve effectiveness. This is added to obvious benefits that armour that resist high velocity impacts reduces the chances of serious injury or death, in peace keeping or combat situations.

Furthermore, the majority of personal armour (annual market value ~£5M) used in the United Kingdom is manufactured in the USA, for both economic and strategic reasons it would be advantageous for that manufacturing to be based here. This project has the potential to affect a step change in armour performance which could then be exploited by our project partners Kennametal Sintec. This would give the UK a competitive advantage allowing Kennametal to increase their market share and would also result in production being moved onshore which is strategically beneficial for the country. As in the past lack of production by other countries at times of need has resulting in supply shortages in the UK.

Finally the improvements in testing equipment and test methodologies either for small scale experiments or impact experiments will be available to the rest of the community either academic or industrial. It could be foreseen that for example the insitu TEM capabilities could be useful the cutting tool industry where hard brittle materials coming to contact with work pieces over small contact areas, generating very high stresses, and complex deformation patterns.


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Description We have been able to show that silicon doping of boron carbide can suppress the high pressure phase transformation. This opening up the possibility of born carbide being used as a high performance light weight armour.
Following on from this we have been able to increase the production of material by a factor of 100.
Exploitation Route This materials is in the processing of being high velocity impact tested.
Sectors Aerospace, Defence and Marine

Description Development of the UK's first portable 2-stage gas gun system has resulted in new opportunities for commercialisation and application in new research directions. The performance of the system (capable of achieving 4.7 km/s impact velocity) helped foster a new research collaboration with First Light Fusion, resulting in sponsored PhD studentships, joint research council proposals, and sponsored experimental campaigns at the European Synchrotron in Grenoble. This research into cavity collapse dynamics has furthermore attracted attention at international conferences and will soon materialise in the form of multiple joint research articles. Looking to the future, the 2-stage platform, along with single-stage variants, is being set-up as a Small Research Facility to provide access to the wider high-rate and shock user communities.
First Year Of Impact 2017
Sector Aerospace, Defence and Marine,Energy
Impact Types Economic

Description 3 Year Research PhD-Silicon Carbide Ceramic Nanocomposites for Armour Firm price
Amount £189,383 (GBP)
Funding ID DSTLX1000133333 
Organisation Defence Science & Technology Laboratory (DSTL) 
Sector Public
Country United Kingdom
Start 10/2019 
End 10/2022
Description Consulting - First Light - 2014
Amount £3,000 (GBP)
Organisation First Light Fusion Ltd 
Sector Private
Country United Kingdom
Start 04/2014 
End 04/2014
Description First Light Sponsored Research Funding - Plasma Physics
Amount £1,000,000 (GBP)
Organisation First Light Fusion Ltd 
Sector Private
Country United Kingdom
Start 03/2016 
End 03/2021
Description Knowledge Transfer Secondment
Amount £58,097 (GBP)
Funding ID PSC250_PHPL 
Organisation Imperial College London 
Sector Academic/University
Country United Kingdom
Start 04/2016 
End 03/2017
Description MAST
Amount £187,000 (GBP)
Organisation Defence Science & Technology Laboratory (DSTL) 
Sector Public
Country United Kingdom
Start 03/2014 
End 09/2016
Description Microstructrually aware energetic materials modelling
Amount £614,838 (GBP)
Funding ID DSTLX-1000144542 
Organisation Defence Science & Technology Laboratory (DSTL) 
Sector Public
Country United Kingdom
Start 01/2020 
End 01/2023
Description Reactive materials
Amount £145,000 (GBP)
Organisation Defence Science & Technology Laboratory (DSTL) 
Sector Public
Country United Kingdom
Start 11/2019 
End 11/2020
Title 2-stage precision light gas-gun 
Description This is a small-bore 2-stage light gas-gun, designed by the Institute of Shock Physics. The output bore of the system is 10 mm, and is constructed to deliver 1g projectiles at 4 km/s. The system is roughly 4 meters in length, and is operated remotely through a LabVIEW interface. 
Type Of Material Improvements to research infrastructure 
Provided To Others? No  
Impact This 2-stage is one of only a few such systems in the UK, and is particularly distinguished by its small size and focus on precision impact. The system has attracted significant third party interest (AWE, First Light). 
Title Novel Diaphragm Fabrication 
Description This innovation relates to the development of a novel approach for fabricating high-pressure diaphragms, bursting at reliable pressures for the second stage of a two-stage gas gun. The conventional approach involves machining a thin sheet of plastic or metal with a groove of known depth using a drill, a time-consuming process. Our approach is to substitute the mechanical scoring with a high-power laser grooving method, which is more cost effective and produces equivalent reproducibility. 
Type Of Material Improvements to research infrastructure 
Year Produced 2016 
Provided To Others? Yes  
Impact This technique has led to an alternative method of producing diaphragms, which relieves reliance on external manufactures. 
Title Time resolved Raman spectrometer 
Description The Raman system developed in this project is a home-built set-up optimised for collection of low intensity, time-gated Stokes scattering light in back-reflected geometry. The system is tailored to meet the fast, low light conditions typical of Shock Physics experiments, allowing the characterisation of high-pressure, high-rate dynamic compression of condensed matter via the time evolution of Raman signatures for Raman-active materials. It features probe beam delivery to the sample by free space for the maximisation of probing density power, light collection performed ex-situ by a remote parabolic mirror for easy coupling to the target chamber at the loading platform, and an optimised interface to the range of high-sensitivity gated detectors available at the ISP. 
Type Of Material Improvements to research infrastructure 
Provided To Others? No  
Impact This system is the first spectroscopic tool developed for the Institute of Shock Physics at Imperial College and is expected to underpin future research proposals for the study of high-pressure phenomena such as dynamic phase transitions under shock compression. This strategy is expected in its turn to lead finally to the creation of a full spectroscopic suite at the ISP. 
Title Cavity collapse sequence 
Description Using the 2-stage gas gun developed in this project, we have been able to acquire high-speed X-ray radiographs revealing the impact-driven collapse of a cavity from low speed through to the hydrodynamic regime. Prior measurements have relied upon visible illumination sources, and as such suffer strong distortion effects due to refraction, or are entirely missed due to attenuation through the compressed target. The data from distortion-free, high-resolution X-ray imaging constitutes a unique experimental dataset which has attracted much interest from the modelling community, and is expected to improve constitutive understanding of materials at these extreme impact conditions. 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? No  
Impact This data is presently included in a journal submission, and will be made available to the wider scientific community through a DOI upon publication. The data has also led to new collaborations with researchers in the US, and the preparation of two additional joint-papers. 
Description Collaborative research with First Light Fusion 
Organisation First Light Fusion Ltd
Country United Kingdom 
Sector Private 
PI Contribution As part of this EPSRC project, our research team has designed and constructed a small-bore two-stage light gas gun capable of achieving impact velocities nearing those believed required to initiate fusion reactions in novel target geometries, of interest to First Light Fusion. Our team has provided knowledge of the theory and operation of two-stage gun systems, including novel diaphragm fabrication methods, through the principal post-doctoral researcher funding by this grant, Dr JP Duarte. Additionally, our team has helped secure access to the European Synchrotron Radiation Facility (ESRF) for pioneering dynamic X-ray radiography experiments utilising the newly constructed two-stage gas gun through a competitive bid process, leveraging the expertise of the Co-I, Dr Daniel Eakins. Dr Eakins has taken on primary supervision of two new PhD students, supported through a combination of First Light Fusion and the ESRF funding, the latter of which was awarded following a competitive bid by Dr Eakins (and worth ~£28k).
Collaborator Contribution In addition to the £1m contributed by First Light Fusion (and reported elsewhere) due to the complementarity of research and experimental capabilities presented by the two-stage gun developed under this project, FLF have provided £15,000 in additional equipment and experimental resources needed to underpin the upcoming joint ISP/FLF ESRF experiment (May 2017). FLF have also previously provided high-value cavity targets for earlier de-risking ESRF runs by Dr Eakins, for exploring the limits of material strength under dynamic compression, and thereby benchmark their hydrocodes. More recently FLF have loaned use of a Shimadzu X2 high-speed framing camera (estimated value £140k) for a second ESRF run by Dr Eakins, to explore novel imaging techniques which might be attractive for the upcoming joint experiment. In terms of supporting staff, FLF have acted as the external organisation towards a successful Knowledge Transfer Secondment secured last March. In addition, FLF have agreed to provide bridging funds to support Dr JP Duarte through the end of May, allowing Dr Duarte to lead the joint ESRF experiment in early May.
Impact -Successful proposal for ESRF beamtime to conduct cavity collapse experiments using the new two-stage gas gun
Start Year 2016
Title 2-stage Matlab simulation tool 
Description This tool simulates the velocity of a projectile in a 2-stage gas gun, allowing tuning of the pump and launch tube length, diameters, transition section, and fill gas pressures. 
Type Of Technology Software 
Year Produced 2014 
Impact This was the principal tool used to design the new 2-stage gun platform developed for this project. During commissioning the gun was shown to successfully achieve the targeted impact velocity of 4 km/s. 
Description Research Seminar at HEMI 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Dr. Daniel Eakins visited the Hopkins Extreme Materials Institute, delivering a seminar to an audience of postgraduate researchers and academics describing various research conducted in the ISP, including work on Hexagonal Materials and Boron Carbide. This talk resulted in a formal link between the ISP (Imperial College) and HEMI (Johns Hopkins University), where collaboration on Hexagonal Materials is one of the primary points of interaction.
Year(s) Of Engagement Activity 2015