Affordable Diffusion Bonding (ADB) of laminate sheet to produce micro-cellular structures relevant for ultra-lightweighting and high efficiency thermal and chemical devices for the aerospace, automotive, medical, chemical manufacturing sectors.
Submitting InstitutionUniversity of Wolverhampton
Unit of AssessmentAeronautical, Mechanical, Chemical and Manufacturing Engineering
Summary Impact TypeTechnological
Research Subject Area(s)
Engineering: Manufacturing Engineering, Materials Engineering
Summary of the impact
Diffusion bonding (DB) is well-known for producing structured materials
with fine scale features and is a critical technology for high efficiency
reactors, e.g. heat exchangers and fuel cells, but currently equipment is
slow and expensive (and there are size limitations to the `assemblies'
that can be built). The University has researched and developed, with
industry partners, a rapid affordable diffusion bonding (ADB) process
involving direct heating to provide appropriate temperature and stress
states and utilising flexible ultra-insulation (vacuum) for pressing
titanium (and now aluminium) sheets together. The process operates at low
stresses thus avoiding `channel' collapse. Investment is taking place in
the partner companies to exploit the technology. A breakthrough has been
achieved in the chemical machining of three dimensional structures for
laminar flow technology assemblies in aluminium and titanium, that can be
built by ADB.
The basis for ADB stemmed from initial needs to reduce the high cost of
machinery and the long hours required to achieve diffusion bonds. Our
research proved that it was possible to eliminate the large expensive
pressure vessels, necessary in the conventional DB process, and, by using
local heating; good bonds could be achieved in less than a minute . The
principal researchers associated with the case study are Professor
F.R.Hall (joined the University 1998, left 31/07/2013) and P.J.Spence
(joined the University 2002). Co-investigator is N Emekwuru (joined the
The research led to work on a lower capital equipment cost process and a
test rig demonstrator for the bonding process with Ajax Tocco Ltd
(Birmingham), UNIPART (Coventry), Rolls-Royce, BAe and UTC HS Marston
(Wolverhampton) (2007 to date) which shows its applicability to other
areas of manufacture, apart from aerospace components . The Department
of Trade and Industry (DTI) through the Advanced Technology Exploitation
Programme (ATEP) provided funding for the work . A patent for the
process is pending (detail is given in part 4 of this case study). The
University research input was the simulation analysis and test validation
of the thermo- mechanical parameters and their application to bonding
titanium. The University also devised the closed loop feedback control,
and the development of a high temperature vacuum insulation environment,
which (being very thin) enabled efficient coupling of the induction
heating equipment from outside the vacuum region (no contact heating is
required thus eliminating contamination issues).
Research through a KTP with Advanced Chemical Etching (ACE) Ltd. , has
led to the development and introduction of new etching chemistries for the
chemical machining of three dimensional structures for laminar flow
technology assemblies in aluminium and titanium used in the Aerospace,
Automotive and Oil industries for fuel cell and heat exchanger type
products. These complex plates are joined together using brazing or
diffusion bonds. The intricate plates once bonded form fine complex
channel arrays to carry both fluids and or gasses. The University, ACE and
Ajax Tocco are collaborating to match ADB to the precision laminates. This
will be particularly advantageous for larger structures (a limitation with
Linked to this is work on a MoD Shrivenham contract: Development of
Innovative Energy Absorbing Light Weight Armour (Confidential) with BAE
Systems. The University was responsible for the numerical simulation; new
laminate designs were evaluated using the University supercomputer of high
speed penetration by projectiles, up to 2 km/s speeds, from a gas gun.
. A range of cell structure designs were analysed, this included
stability of impact behaviours against off-axis perturbation and effects.
The work is concerned with development of new armour systems for
lightweight agile vehicles. Promising results were obtained with
multi-material laminate structures to defeat high speed projectiles. These
structures would be suitable for manufacture using the ADB technique to be
The research undertaken has involved extensive use of numerical modelling
and more recent simulations have shown that the knowledge gained in the
ADB research, i.e. utilising localised heating of the workpiece, can be
extended to superplastic forming (SPF), to offer a more cost- effective
approach to SPF especially when combined with ADB. The research offers a
unique approach in SPF by applying selective heating whilst keeping dies
at a lower temperature (contact friction is reduced) .
References to the research
1. Peter J. Spence, Frank R. Hall , Nwabueze Emekwuru, "Preliminary study
of improving the speed and cost of diffusion bonding of metal sheets",
Proceedings of the Institution of Mechanical Engineers, Part B: Journal of
Engineering Manufacture, Published online before print September 2, 2013,
doi: 10.1177/0954405413498584 (Output 1 for Spence)
2. Richard Hall, Julian Spence, Chris Kenward, Dave Scott, Dave Townsend,
Midlands Aerospace Alliance presentation, June 2008.
3. ATEP 1 Aerospace Technology Exploitation Programme) funded (internal
project number C5136), Oct 2006 to Apr 2008)"Affordable Diffusion
4. KTP Advanced Chemical Etching Ltd (no. 8230).
5. IN CONFIDENCE COMPETITION OF IDEAS "Innovative Lightweight Energy
Absorbing Armour" Contract No: RT/COM/5/006 Project Progress Report.
6. Michal Mis, Richard Hall, Julian Spence, Nwabueze Emekwuru, Kevin
Kibble, (2013), Numerical study of radiation and temperature phenomena for
improved super-plastic sheet metal forming, Materials Science Forum, Vol.
735, pp. 170-179. (Output 2 for Spence)
Details of the impact
Key step 1 was the ATEP I project: (laminate technology R&D).
Core income of £64k (ATEP1+2), with match funding from the partners (total
~£300k) by the "Midlands Aerospace Alliance" and involving UTC HS
Marstons, BAe, Rolls-Royce, AJAX Tocco and UEES: Development of the
affordable diffusion bonding process. This ATEP project demonstrated for
the first time localised induction heating can create a high speed
diffusion bond (for Ti-6Al-4V), within 30 seconds; traditional methods
take at least 8 hours) utilising an innovative new technique, involving
vacuum insulation . A patent is pending for detailing the technology
developed in the ATEP .
BURCAS (KTP): "Improving the brazing process at Burcas knives
division". The University supervised this KTP and collaborated with the
original ATEP (DB) partner AJAX Tocco in developing the brazing process,
defining and proposing machinery for improved and faster (and cheaper)
brazing of large (5 m) industrial knives as well as for improved heat
treatment of cutting edges, through localised induction heating
technology. This KTP extended the research knowledge of selected localised
heating necessary for the ADB process .
Key step 2 concerned the reputation gained by the University in ATEP 1
and led to further work in the development, design and manufacture of
materials based on laminated layered manufacture, i.e. the MoD funded
project "Competition of Ideas" in collaboration with BAe. This
project involved the design of cellular materials, by numerical
simulation, for impact energy absorption and based upon DB/SPF. This
included the development of different geometries and topologies for the
cellular structure and their behaviour under conditions of high speed
Key step 3 was a second ATEP 2 project TASC: Advanced Surface
Cooler technology development with HS Marston, Rolls-Royce, and ACE Ltd.
(Feb 2009 to Apr 2011) . In particular the collaboration with ACE Ltd
resulted in a KTP project (no. 8230). Advanced Chemical Etching (ACE)
Ltd (laminate technology work): To use advanced chemical etching
linked to the affordable diffusion bonding process to manufacture highly
intricate structures for various applications, aerospace, automotive, and
other high value manufacturing.
ACE Ltd (KTP): The aim of the project was to improve the existing
chemical etching process for aluminium and titanium components used in
aerospace applications. This derived from working with H S Marston (UTC)
on developing shim plates for compact heat exchanger units requiring micro
channels. The result of the project is new chemical etching processes
capable of consistent and repeatable high quality component product. The
new technology has proved to be 4 to 5 times quicker and capable of
extending the life of chemicals used tenfold from the existing process.
With significant confidence in the new processes, ACE has invested
extensively both in buildings and new machinery, supported by increased
sales and marketing activity, as well as increased investment in R&D.
The value of KTP to ACE has been in changing the mentality within the
company to use `Science' in their everyday business dealings 
The work undertaken has significantly enhanced the capability of ACE for
the processing of new technology components in titanium and aluminium
alloys which had previously been out of reach. Laminar Plate Technology is
in increasing demand for new generation developments of miniature heat
exchangers for cooling electronic devices to light-weight aero engine
fluid heat exchanger assemblies not available before. This development has
had a significant impact on the continuing success of ACE's business both
in the UK and internationally to give the company the confidence to
undertake a recent substantial expansion of the business .
Linked to this research and development has been the need to investigate
alternative methods of bonding leading to a further collaboration using
the selective DB technology, developed by Ajax Tocco and the University,
in identifying a significant practical application for the oil industry to
use these new chemical etching processes [6, 7]. .
Further investments have been obtained and work is on-going to complete
the development of the ADB process, with AJAX TOCCO, ACE and The
University (HEIF-Fellow, Senior Research Fellow, and Research Fellow-in
MidSim to support this R&D). Ajax TOCCO International Ltd are still
actively involved with developing the diffusion bonding process, in
collaboration with the University of Wolverhampton, and doing this with
equipment located at the Saltley site of Ajax TOCCO International Ltd.
Currently this includes the investigation of a titanium bond for a part to
be used in the oil and gas industry. In addition they are considering how
to do bonding on somewhat larger parts but in an aluminium alloy .
Sources to corroborate the impact
- ATEP I (Aerospace Technology Exploitation Programme) funded (internal
project number) C5136, Oct 2006 to Apr 2008)"Affordable Diffusion
Midlands Aerospace Alliance (who organised the ATEP )
- Filing of World patent for DB process http://patentscope.wipo.int/search/en/WO2011012906
full Status copied to
- Burcas KTP 7503, "To investigate the existing metal bonding manual
process, devise an automated replacement, and embed technologies to
improve productivity." July 2009 to October 2011. Final Report:
COMPETITION OF IDEAS "Innovative Lightweight Energy Absorbing Armour"
Contract No: RT/COM/5/006 Project Progress Report. Confidential.
- ATEP2 TASC: Advanced Surface Cooler technology development with HS
Marston, Rolls-Royce, and ACE Ltd. Funded by RDA, Midlands
- October 2012 Personal communication Alan Rollason Chairman ACE,
Telford, wants to invest further in laminate technology with the
University as partner.
- Letter of support providing details from Alan Rollason Chairman,
Advanced Chemical Etching, Unit 31-34 Hortonwood 33, Telford, TF1 7EX,
Tel: 01952416666, October 2013.
- Letter of support, providing details, Chris Kenward, Process
Engineering Manager, Ajax Tocco International Ltd, Saltley, Birmingham,
B8 1BGL, Tel. 0121 - 322 - 8028.
- Philip Hyland, Director of Operations, Ajax Tocco International Ltd,
Saltley, Birmingham, B8 1BGL, email correspondence to J Spence