Micro Materials Latest News

MML establish new US service centre

Mon, 10 Jan 2011 00:00:00 +0000

MML are very pleased to announce the establishment of our full time US service centre, which is based in Denver, Colorado.

The centre, set up in conjunction with our local representatives RGS Scientific, will act as a technical support hub for the ever-growing customer base in North America.

The service will be lead by Tim Jochum (pictured), who was specially selected by RGS and MML for the post due to his strong background in materials science and technical capability.

Tim is a graduate of Colorado School of Mines (MSc Materials Science) and Texas A&M University (BSc Chemistry).

Micro Materials Ltd renews distribution network in India

Wed, 08 Dec 2010 00:00:00 +0000

Micro Materials Ltd (Wrexham UK) have announced the renewal of their representation channels in India. MML have formed a partnership with Tesscorn Systems India Private Ltd (Tesscorn), a representative company who have been established in the Indian market since 1994, with offices in Bangalore, Delhi and Kolkata.

Commenting on this partnership, Denise Hoban, International Business Development Director of MML said 'Tesscorn have an excellent track record in the sale of high performance and cutting edge scientific research equipment. This new partnership between MML and Tesscorn will benefit our existing user base and will serve to promote the unique capabilities of the NanoTest system further within the Indian market. We were particularly impressed with Tesscorn's reputation for excellent customer support, and the rapport they have with their customer base.'

Ramesh Athihalli, Director of Tesscorn stated 'Working with MML allows us to offer the customer something different to what is currently available in the Indian market in the field of nanomechanical testing. Their NanoTest system has clear advantages for researchers, and the response so far from the nanomechanical community in India has been extremely positive. '

Ramesh Athihalli

Established in 1988 Micro Materials Ltd are manufacturers of the innovative NanoTest system, which offers unique nanomechanical test capability to materials researchers for the characterisation and optimisation of thin films, coatings and bulk materials. Techniques include nanoindentation, nano-scratch & wear, nano-impact & fatigue and nano-fretting.

Tesscorn Systems India Pvt Ltd is a leading distributor of integrated products, services and support to the research and development community in India, including Automotive, Defense, Aerospace, Military Forces and Universities. They are focusing their efforts on the nanotechnology industry with an intention to exceed customer expectations by providing the best in innovative, reliable solutions in products, systems and services.

Further information on Tesscorn can be found at www.tesscorn.com

European User Meeting 10 - Review

Tue, 09 Nov 2010 00:00:00 +0000

The Tenth MML European User Meeting took place on Oct 27th - 28th 2010 at Politecnico di Milano, Milan. The meeting was highly successful, with excellent speakers providing a useful insight into the relevance of nanomechanics in a whole host of diverse application areas. We thank all those to contributed and all the delegates for their attendance and finally we would like to thank Prof Pasquale Vena and his group at Politecnico di Milano for hosting us.

Fig 1: Politecnico di Milano - Dipartimento di Ingegneria Strutturale.

The meeting was opened by Paul Grasske, Managing Director of Micro Materials Ltd. The recent news of MML returning to private ownership was shared as this has brought new investment to the organisation. There was also a short introduction to the excellent benefits of the improved Platform 3 of the NanoTest system and a round up of all the new European NanoTest users.

This was followed by a short welcome talk by Professor Pasquale Vena, Politecnico di Milano who spoke about the diverse research lines at the Department of Structural Engineering (Dipartimento di Ingegneria Strutturale) and in particular the Laboratory of Biological Structure Mechanics (LaBs), established in 2000. The research topics include the area of Micromechanics of Biological Structures and Biomaterials that rely on several experimental facilities to match their research level, including MML's NanoTest.

The opening session of the meeting was chaired by Professor Pasquale Vena of Politecnico di Milano.

Fig 2: Simulated indentation comparing a model with Residual Stresses (bottom) to that without (top), Prof Bill Clyne.

Prof Bill Clyne of The Gordon Laboratory, University of Cambridge opened the session with a presentation on high strain rate impact indentation and the use of quasi-static indentation for residual stress measurements. He showed that pendulum based indentation, which the NanoTest employs, provides the flexibility to carry out nanoindentation in impact mode, with some challenges in the modelling.

Prof Clyne concluded that it should be possible to infer constitutive relations, including strain rate dependence, from impact indentation data, using displacement histories & residual indent shapes and although sensitivities are likely to be relatively low at the moment, good progress is being made.

Dr Alessandro Patelli of CIVEN, Venice, Italy presented the use of nanoindentation and microscratch in the optimisation and characterisation of coatings for industrial applications and gave an overview of the different coatings produced at CIVEN and their materials characterisation.

Dr Patelli discussed the many industrial needs for different substrates for specific applications, in particular the plastics, mechanics and production processes involved in optimising nanostructured hard coatings, barrier coatings and antiscratch coatings. After thermal annealing, nanoindentation showed an increase in hardness for all coatings and micro scratch showed a critical load decrease due to internal stresses. In micro scratch tests, high TiB2 content showed that fracture is typically fragile exhibiting buckling and spallation. With patented anti-scratch coatings, Dr Patelli showed how there is a positive correlation between scratch resistance and layer thickness and used the additional NanoTest output of friction results to support this. The effects of hot embossing on the change in mechanical properties of the coatings before the glass transition temperature were illustrated from results extracted from high temperature indentation tests. Overall, Dr Patelli concluded that the nanoindentation and micro scratch tests are fundamental tools for the development of such coatings.

Fig 3: Dr Vineet Bhakhri of Imperial College London.

Dr Vineet Bhakhri of Imperial College London presented the mechanical deformation behaviour of ceramic and metallic systems at elevated tempatures. He showed that by performing nanoindentation tests at several temperatures up to (500°C) 773K with a high temperature MML NanoTest indenter, average thermal drifts of 0.02 nm/sec at (200°C) 473K and 0.06 nm/sec at 773K were recorded.

In the metallic system where Gold was used, a Haasen plot activation analysis of the deformation process indicated that more mechanical work must be applied during the constant-loading rate stage of the nanoindentation test, due to the predominance of work hardening, compared to the constant-load stage where considerably more dislocation recovery occurs. Supporting TEM investigations confirmed that dislocation interactions were the deformation rate controlling obstacles at high temperature.

In the ceramic system, where Ti_0.44 Al_10.56N coating was used, both the Elastic modulus and Hardness remained constant over the tested range of temperatures from (27°C) 300K to (350°C) 623K. In this case it was found that lattice resistance glide is the deformation rate controlling mechanism. Dr Bhakhri concluded that the MML high temperature nanoindentation technique used was sufficiently precise in the investigation of the kinetics of plastic deformation in the ceramic and metallic systems.

The second session of the day was chaired by Prof Bill Clyne of the University of Cambridge.

Fig 4: Prof Edoardo Bemporad of Universita degli studi Roma Tre.

Prof Edoardo Bemporad of Universita degli studi Roma Tre opened the session with a talk on the preparation of milled micropilars in a 3.8μm CAE-PVD TiN coating on a WC-Co substrate, an an innovative combination of focused ion beam (FIB) machining and subsequent nanoindentation testing to study the effect of surface elastic residual stress on their nanomechanical behaviour.

Prof Bemporad mentioned that nanoindentation techniques can represent an alternative in the field of stress measurement at the micro-scale due to its relative speed, cost, automation and ease of coupling with FIB.

The average residual stress was calculated by two different sets of load-depth curves, the first one obtained at the centre of stress relieved pillars and the second one from the undisturbed (residually stressed) surface. In addition, nanoindentation on stress relieved pillars also enabled a more accurate evaluation of Young's modulus and the Hardness of the coating.

High load nanoindentation and application of energy methods for fracture toughness evaluation were used to study the effect of residual stress on crack propagation modes. It was found that compressive residual stress plays a relevant role in determining the fracture behaviour and failure modes of the coating. The microstructural observations by TEM analysis on the cross section of the indentation showed plastic deformation at the nano-scale occurs by formation of shear bands inside the columnar grains, independently of residual stress. Prof Bemporad concluded that the method shows good promise and future work involves the application of this method to metallic and amorphous materials and multiphase materials (for intergrannular stress evaluation).

Fig 5: Focused ion beam (FIB) micro pillars where used to create areas free of the residual stresses from the bulk material [M.Sebastiani, E.Bemporad, Philosophical Magazine 2010, 1-16].

Fig 6: Size effect on cracking in silicon micro pillars, top pillar diameter ~ 5um, bottom ~300nm

Dr Sandra Korte of University of Cambridge presented a talk which looked at microcompression testing at elevated temperatures and in particular the effect of size on cracking in ceramics and the results and considerations for conducting microcompression experiments on silicon micropillars at temperatures up to 500°C degrees.

With MML's NanoTest, uniaxial microcompression tests without confining pressure were used to avoid any affect on deformation mechanisms, and preferred for characterization of individual slip sytems since with nanoindentation, confinement of the surrounding material would mean all slip systems would be activated regardless of the critical resolved shear stress and phase transformation under pressure. The suspected transition in dislocation structure was studied through the preparation of TEM specimens.

Dr Korte also showed that testing at high temperatures is necessary due to thermal activation of dislocation motion against the resistance of the crystal lattice in bcc metals and ceramics. The results showed reliable stress-strain data at upto 500°C, 2μm diameter micro pillars that were plastic from 200°C without confining pressure (300 nm diameter at RT) and yield stresses that were in good agreement with literature, particularly at high stresses and again, this was supported by successful TEM characterisation.

Dr Nick Bierwisch of Saxonian Institute of Surface Mechanics (SIO) presented complimentary software developments which correct the time dependent displacement effects in nanoindentation analysis.

Dr Bierwisch stated the importance of such a correction between analysis and real-coating substrate systems especially at high temperatures due to the temperature dependency of mechanical properties, in particular Young's modulus, Yield strength and Hardness.

In the determination of physical parameters by nanoindentation, Dr Bierwisch showed how SIO have extended the standard Oliver & Pharr analysis method which gives only effective Young's modulus and Hardness to include coatings that may be inhomogenous due to layers and gradients and also for time dependent material behaviour due to creep and high temperature. Dr Bierwisch concluded by saying that these methods are simpler and provide new possibilites in the fields of surface testing and material optimisation.

Fig 7: Discussions during the coffee and poster breaks.

Prof Ben Beake of Micro Materials Ltd concluded the second session by speaking on nanoindentation creep on viscoelastic materials above and below the glass transition temperature.

Prof Beake showed that since accurate modelling of the viscoelastic properties of polymeric materials rely heavily on the quality of experimental data then important tests such as the constant load creep tests carried out on PMMA can help identify the influence of instrumental stability on the accuracy of modelling indentation creep.

The first indication of loss of modulus is from equating the unloading modulus with the storage modulus and tan delta from the strain rate sensitivity calibration chart since for a given indenter geometry there is an approximate correlation between the strain rate sensitivity parameter and tan delta. Tests on uniaxially drawn PET films at elevated temperatures show a peak in the loss modulus in the vicinity of the glass transition. Prof Beake also spoke on how the mechanical properties and creep behaviour of atactic-polypropylene were studied around its glass transition temperature using the sub-ambient temperature capability of the NanoTest. These tests showed an influence of the glass transition on the creep response and indirectly onto Hardness and Young's modulus from the unloading analysis.

Fig 8: Discussions during the coffee and poster breaks.

The third session of the day was chaired by Dr Marc Masen of the University of Twente.

Prof Mojtaba Ghadiri of the University of Leeds opened the session with a presentation on the fracture behaviour comparison of Aspirin under quasi-static indentation and single particle impact loading and the effect of cleavage planes, an investigation that has been carried out with the use of MML's NanoTest NTX3. Prof Ghadiri spoke about how under both quasi-static testing conditions, using nano-indentation and dynamic impact tests, Aspirin demonstrated a stong anisotropy in its fracture behaviour. During nano-indentation tests on the (100) and (001) faces, cracks propagate in the [010] direction on the (001) and (100) fracture planes, respectively. While the Hardness is found to be similar for both faces, slip occurs more readily on the (100) then (001) plane, suggesting the former to be the preferred slip plane. Furthermore, the fracture toughness of the (001) plane was distinctively lower than that of the (100) face, which indicated that the (001) is the preferred cleavage plane of the material. Observations of the damage morphology of the particles after dynamic impact testing showed that both chipping and fragmentation of Aspirin occur via cleavage planes, which is in good agreement with observed fracture mechanisms during nano-indentation. Prof Ghadiri concluded by saying that the presence of cleavage planes is a dominant factor in the fracture mechanism of Aspirin under quasi-static and impact loading conditions and therefore when nanoindentation is used as a predictive tool for breakage mechanisms under impact loading conditions, the fracture anisotropy of a material should be considered.

Dr Davide Carnelli of Politecnico di Milano detailed the work he has carried out on nanoindentation tests, using MML's NanoTest, on tissue engineered rabbit bone with ASCs (adipose-derived stem cells)that were used for regeneration of full thickness bone defects in proximal epiphysis of tibia of twelve New Zealand rabbits. The defects were implanted with graft material in two scaffold treatment groups: a empty hydroxyapatite disk and then in a hydroxyapatite disk seeded with ASCs and although both showed similar mineral properties after 8 weeks, the result of histological analyses showed that the osteogenic abilities of the scaffold-treated defects were greater than the scaffold free samples (those with untreated defects). Nanoindentation tests (maximum loads 1mN, 5mN and 50mN) were adopted to characterize the mechanical reponse of tissue engineered bone obtained through the two different treatments and out of the two scaffold treated groups, the cell-seeded scaffold construct (hydroxyapatite disk seeded with ASCs) showed significantly higher siffness and hardness at the shallower depths (200-500 nm) but lower at the higher depths (2000 nm) against the empty hydroxyapatite disk defect treatment. When both were compared to the native tissue, the latter was stiffer at all scales except against the cell-seeded tissue which was still stiffer at the shallower depth. Dr Carnelli mentioned that further investigations would include a relationship between maturity and mechanical properties since there is an indication that mechanical properties of tissue engineered bone in the early stages of the healing process are higher due to higher mineral content.

Fig 9: Nanoindentation tests on tissue engineered rabbit bone, as presented by Dr Davide Carnelli of Politecnico di Milano.

Dr James Dean of the University of Cambridge presented recent findings from sub-ambient temperature indentation. Dr Dean spoke about the operation of the cryostatic indentation stage that has been developed in the Gordon Laboratory, Cambridge, allowing indentation tests to be performed at temperatures as low as -170°C. To prevent condensation and hence a faster cooling system, the indentation tests were conducted inside a vacuum chamber (10-6 hPa). This allowed a study of the nanomechanical properties, from preliminary indentation tests, to be investigated over a range of temperatures but also at high strain rates, and it follows that below the glass transition temperature a much higher load (almost 4 times) was required to reach the same depth as tests carried out at room temperature. Dr Dean also spoke on the use of nanoindentation to measure residual stresses in surface layers, and residual stress generation, which showed matching experimental and curve fit models of creep strain at various loads but in particular at lower loads. The experiments also showed decreasing peak indentation loads and hardness with increasing in plane residual stress and stability against the imposed temperature drops where the experimental values of indentation loads and hardness were lower and then higher respectively in comparison to the predicted models.

The last session of the day was chaired by Prof Ben Beake of Micro Materials Ltd.

Dr Marc Masen of the University of Twente opened the last session with a talk on an investigation into two- and three-body abrasive wear whereby it was stated that a non-statistical approach is required when modelling abrasive wear. This is because many surface models in tribology are based on the assumption that surfaces are composed of a collection of small asperities e.g. the well known Greenwood and Williamson models which assume the asperities are equally sized and spherically shaped with a defined height distribution. Dr Masen presented work that initially focused on the behaviour of a single asperity in scratching contact (scratch test) with a counter surface which employed MML's Micro Test pendulum and the wear scars were measured using an interference microscope to quantify the volumetric wear as a function of indenter shape and normal load. Thus, knowing the behaviour of the unit-event, the total abrasive wear volume on the surface can be more closely achieved. It follows that such an approach is also possible for three-body abrasive wear i.e. when the scratching action is made by a particle that is not an asperity on one of the contact surfaces e.g. when driving through a sand storm. Dr Masen concluded by presenting experimental work into the abrasive properties of sand i.e. the study of the influence of a sand particle properties on abrasive wear. The approach included measuring the properties (hardness, size and geometry) of different sand samples and developing a model for scratching sand particles and then to perform dry sand rubber wheel tests.

Fig 10: SEM images of a pin on disk scratch technique, presented by Dr Marc Masen of the University of Twente

Dr Gerard Bell of of Micro Materials Ltd and the University of Birmingham and Dr Jian Chen also of the University of Birmingham were the last speakers of the day and presented the work they did together on the low temperature mechanical properties and nano-scratch study of a graded a-C:H(Ti)/TiCN/TiN/Ti tribological coating. The investigation included the first low temperature (25°C to -30°C) nanoindentation which took advantage of the stability of the NanoTest's recent upgrade to Platform 3, which provides additional stability when working at non-ambient temperatures and has faster calibration and a new soft-balancing system which eliminates the pendulum mass balance adjustments when changing between indenter types. It was found that room temperature scratch tests failed the coating, but at 0°C, a significant increase in Hardness/Young's modulus. Resistance to crack propagation increased consistently with decreasing temperatures down to -30°C. Dr Bell stated that the new sub-ambient capability is one that allows the ability to probe the tribological properties of surface engineered systems on the nano and micro scales. Furthermore, this advanced testing technique can be used in many applications including aerospace, automotive and polymer industries and in conjunction with other types of tests including nano-impact, scratch and wear, which MML's NanoTest is well suited for.

Fig 11: Low temperature (-30°C) scratch testing showing how surface damage changes due to drop in temperature. Presented by Dr Gerrard Bell and Dr Jian Chen of the University of Birmingham

If you would like any further information on any of the talks or would like to be informed of next year's European User Meeting, and for any general queries related to Micro Materials Ltd please contact tahsin@micromaterials.co.uk

Micro Materials returns to private ownership

Thu, 01 Jul 2010 00:00:00 +0100

Micro Materials Ltd (MML), established in 1988, has returned to private ownership following a buy-out by major shareholder David Harding. Mr Harding first became interested in MML via his substantial shareholding in Millbrook Scientific Instruments plc., who acquired MML in 2004.

The company has an impressive record of innovation in the field of nanomechanical instrumentation, which is set to continue under the stewardship and investment of Mr Harding. The new investment will further accelerate the product development programme.

Paul Grasske will continue as Managing Director of MML, working with the existing core management team.

European User Meeting 2011

Tue, 17 May 2011 00:00:00 +0100

Details of the 11th Annual European Nanomechanical User Meeting have now been released. Following a successful meeting in Milan in 2010, 2011 will see the meeting return to the UK for the first time in five years.

This year's meeting will be kindly hosted by Professors Bill Clyne and Bill Clegg of the Gordon Laboratory at the University of Cambridge. Full details can be seen here.

MML Reveal New Instrument

Wed, 01 Jun 2011 00:00:00 +0100

Micro Materials Ltd (MML) today announced the launch of their new instrument, the NanoTest Vantage.

The instrument offers an excellent range of capability for materials research, from nanoindentation to nano-impact & fatigue, allowing the researcher to gain a complete picture of their materials properties, under true service conditions.

Denise Hoban, International Business Director at MML, states ‘Our customers have always appreciated the flexibility of the NanoTest system, and the unique capability it offered. This new generation of instrument allows higher throughput and reduced training time, allowing our customers to focus on unique experiment design. The NanoTest Vantage remains the instrument of choice for the high level researcher, guaranteeing highly publishable, unique data. It’s time for people to take a fresh look at what the system has to offer’.

In the past 12 months MML have stepped up their worldwide presence and are seeing rapid growth in key territories. This new instrument launch will help to further grow market share, and raise awareness of the unique capability available.

Established in 1988, Micro Materials Ltd are manufacturers of the innovative NanoTest system, which offers unique nanomechanical test capability to materials researchers for the characterisation and optimisation of thin films, coatings and bulk materials. Techniques include nanoindentation, nano-scratch & wear, nano-impact & fatigue and nano-fretting.

Further information on the NanoTest Vantage can be found at www.micromaterials.co.uk

Programme for 11th European Nanomechanical User Group Meeting Released

Thu, 28 Jul 2011 00:00:00 +0100

The provisional programme for the upcoming nanomechanical user group meeting has now been released.

The programme features talks on the full range of nanomechanical tests, including indentation, nano-impact, nano-scratch and testing at high temperature. Invited speakers include:

Prof Konstantin Bouzakis, Aristotle University of Thessaloniki

Dr Luc Vandeperre, Imperial College London

Dr Nigel Jennett, NPL

Prof Dariusz Bielinski, Technical University of Lodz

Prof Sarah Hainsworth, University of Leicester.

For full details, including registration information, please click here.

MML are recruiting - International Sales Engineer

Tue, 02 Aug 2011 00:00:00 +0100

Vacancy for International Sales Engineer

Sept 2011 - This vacancy is now filled. Thank you to all applicants.

Micro Materials Ltd is a highly specialised and technologically advanced company specialising in the measurement of mechanical properties on the nanoscale. Due to record levels of interest in our instruments, we seek to appoint an energetic technical sales person, who will report to the International Business Development Director.

Responsibilities will include:

 Supporting an existing network of global distributors

 Delivering technical presentations

 Assisting with marketing campaigns and exhibitions

 Undertaking customer visits and instrument demonstrations

 Organising international events

This position will be based in Wrexham, North Wales, UK, and will include a considerable degree of international travel.

The successful candidate will possess an excellent first degree in Materials Science, Engineering or similar. A further degree or PhD would be an advantage. They will be self-motivated and comfortable working as part of a dynamic and highly effective team. Excellent inter-personal skills and standards of written and spoken English are an absolute must.

Candidates must have a valid permit to work in the UK if relevant.

Closing date for applications: 9th Sept 2011

To register your interest and get further information on this vacancy, please send your CV to info@micromaterials.co.uk

11th Annual European User Meeting - Full review here

Wed, 26 Oct 2011 00:00:00 +0100

Micro Materials Ltd held another successful european user meeting on Sept 27th 2011, at the University of Cambridge. We thank all speakers and attendees, and also our hosts Prof Bill Clyne and Prof Bill Clegg. The setting of the meeting, in Downing College’s neo-classical buildings and beautiful gardens, together with rare September sunshine, gave the meeting a very relaxed and reflective feel.

NanoTest users from all over Europe presented their recent work, covering topics including nano-impact, high temperature nanoindentation, creep at elevated temperatures, standardisation and much more. For a full review click here.

High temperature publications 2011

Mon, 02 Jan 2012 00:00:00 +0000

2011 proved that high temperature nanoindentation continues to be a huge growth area in materials science. The operation and function of the NanoTest instrument from Micro Materials Ltd (MML) at temperatures up to 750°C is now well established and recognised, meaning that the challenge to the nanomechanical community is no longer in the acquisition of reliable data, but in the interpretation of the resulting data produced. 2011 saw the publication of some seminal papers in the area of high temperature nanoindentation. This article will offer a summary of selected work from users of the MML NanoTest system, which was the only instrument to produce publications featuring data above 200°C. This article will précis work carried out at temperatures above 600°C only.

Click here to download the full article

Event List for 2012

Thu, 12 Jan 2012 00:00:00 +0000

See where you can meet members of the MML team in 2012 to learn more about the unique capability of the NanoTest Vantage by checking out our events page.

If you are interested in hosting a workshop or seminar on the subject of nanomechanical testing in your local area, please contact your local MML representative, who will be pleased to help you.

The picture on the right shows Micro Materials staff Mike Davies, Sales & Applications Engineer, Denise Hoban, International Business Development Director, and Tim Jochum, US Service and Sales Engineer, at MRS Fall, 2011.

MML are recruiting for a Production Engineer

Fri, 20 Jan 2012 00:00:00 +0000

Vacancy for Production Engineer

Feb 2011 - This vacancy is now filled. Thank you to all applicants.

Due to record levels of interest in our instruments, we seek to appoint an energetic production engineer, who will report to the Production Manager. This role offers the applicant the opportunity to work in the highest levels of scientific research on a global level.

Responsibilities will include:

- Assembling and testing of new instruments
- Installing and commissioning new instruments at customer’s sites worldwide
- Training of customers on the use of the instrument
- Service and applications support visits
- Contributing to the on-going instrument development

This position will be based in Wrexham, North Wales and will include a considerable degree of international travel, (up to 90 Days per year).

The successful candidate will possess a degree in an Engineering discipline or equivalent, and should be practical, flexible and self-motivated. Engineering experience would be desirable but not essential.

A desire to travel, and to experience and adapt to diverse working environments are essential.

Micro Materials value input from all employees having recently acquired investors in people award, and are an equal opportunities employer.

Closing date for applications: 29th Feb 2012

To register your interest and get further information on this vacancy, please send your CV to paul.aden@micromaterials.co.uk

Versatile micromechanics - vacuum, high and low temperature nanoindentation at Oxford University Materials

Thu, 29 Mar 2012 00:00:00 +0100

Download this article in pdf form

The field of nanomechanical testing has long evolved beyond the evaluation of materials under ambient laboratory conditions. Since 2000 researchers have been pushing to extend the possibilities of the technique, in an effort to make the measurements more realistic to the conditions the materials see in service. Testing at high and low temperatures, high strain rates, in liquids, under gas and under controlled humidity are all now possible.

Professor Steve Roberts (left) and Dr David Armstrong with their NanoTest vacuum system

Testing at high temperature brings many challenges, the main one being oxidation of the sample and the indenter, both of which must be heated to maintain stability during experiments. This also allows a very clearly defined test temperature. While gas purging has been used effectively to reduce oxidation to an acceptable level, the ‘holy grail’ of high temperature nanoindentation was always to be able to do it under vacuum.

Professor Steve Roberts and his group at Oxford Materials worked with Micro Materials Ltd (MML) to produce a dedicated nanoindentation instrument, which achieves vacuum levels of 10^‑06 Torr. The instrument platform itself has been designed to be fully vacuum compatible. The instrument has a useable load range of 10µN – 500mN, and can currently reach temperatures between +750°C and -30°C. There are plans to extend the temperature range down to -150°C.

The instrument also features a piezoelectric nanopositioning stage, which allows the indenter to be used in AFM mode, so that small test elements such as microcantilevers can be located, imaged and tested, to an accuracy of 3nm, over the full range of temperatures.

The instrument, which is to have a full commercial launch by Micro Materials Ltd in the coming months, has successfully completed its initial trials, and is now (March 2012) being used by Dr Dave Armstrong and Dr Ben Britton for their first experiments.

Excellent pioneering work was done in this field at The Gordon Laboratory at Cambridge University, again using a Micro Materials NanoTest instrument. The method used there was to place a standard instrument inside a custom built vacuum chamber, which produced some ground-breaking publications.

Professor Roberts and his research group work predominantly on developing Materials for Fusion & Fission Power and are part of the Materials Department at the University of Oxford, UK.

For further information about the instrument described in this article, please contact Denise Hoban, International Business Development Director at MML. denise@micromaterials.co.uk

+44 (0) 1978 261615

www.micromaterials.co.uk