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Category: Mechanical Testing

 

Adhesion Properties of Gold Coating on Quartz Crystal Substrate

 

Adhesion Properties of Gold Coating

on Quartz Crystal Substrate

Prepared by

DUANJIE LI, PhD

INTRODUCTION

The Quartz Crystal Microbalance (QCM) is an extremely sensitive mass sensor capable of making precise measurements of small mass in the nanogram range. QCM measures the mass change on the surface through detecting variations in resonance frequency of the quartz crystal with two electrodes affixed to each side of the plate. The capacity of measuring extreme small weight makes it a key component in a variety of research and industrial instruments to detect and monitor the variation of mass, adsorption, density, and corrosion, etc.

IMPORTANCE OF SCRATCH TEST FOR QCM

As an extremely accurate device, the QCM measures the mass change down to 0.1 nanogram. Any mass loss or delamination of the electrodes on the quartz plate will be detected by the quartz crystal and cause significant measurement errors. As a result, the intrinsic quality of the electrode coating and the interfacial integrity of the coating/substrate system play an essential role in performing accurate and repeatable mass measurement. The Micro scratch test is a widely used comparative measurement to evaluate the relative cohesion or adhesion properties of coatings based on comparison of the critical loads at which failures appear. It is a superior tool for reliable quality control of QCMs.

MEASUREMENT OBJECTIVE

In this application, the NANOVEA Mechanical Tester, in Micro Scratch Mode, is used to evaluate the cohesive & adhesive strength of the gold coating on the quartz substrate of a QCM sample. We would like to showcase the capacity of the NANOVEA Mechanical Tester in performing micro scratch tests on a delicate sample with high precision and repeatability.

NANOVEA

PB1000

TEST CONDITIONS
The NANOVEA PB1000 Mechanical Tester was used to perform the micro scratch tests on a QCM sample using the test parameters summarized below. Three scratches were performed to ensure reproducibility of the results.

LOAD TYPE: Progressive

INITIAL LOAD

0.01 N

FINAL LOAD

30 N

ATMOSPHERE: Air 24°C

SLIDING SPEED

2 mm/min

SLIDING DISTANCE

2 mm

RESULTS & DISCUSSION

The full micro scratch track on the QCM sample is shown in FIGURE 1. The failure behaviors at different critical loads are displayed in FIGURE 2, where critical load, LC1 is defined as the load at which the first sign of adhesive failure occurs in the scratch track, LC2 is the load after which repetitive adhesive failures take place, and LC3 is the load at which the coating is completely removed from the substrate. It can be observed that little chipping takes place at LC1 of 11.15 N, the first sign of coating failure. 

As the normal load continues to increase during the micro scratch test, repetitive adhesive failures occur after LC2 of 16.29 N. When LC3 of 19.09 N is reached, the coating completely delaminates from the quartz substrate. Such critical loads can be used to quantitatively compare the cohesive and adhesive strength of the coating and select the best candidate for targeted applications.

FIGURE 1: Full micro scratch track on the QCM sample.

FIGURE 2: Micro scratch track at different critical loads.

FIGURE 3 plots the evolution of friction coefficient and depth that may provide more insight in the progression of coating failures during the micro scratch test.

FIGURE 3: Evolution of COF and Depth during the micro scratch test.

CONCLUSION

In this study, we showcased that the NANOVEA Mechanical Tester performs reliable and accurate micro scratch tests on a QCM sample. By applying linearly increased loads in a controlled and closely monitored fashion, the scratch measurement allows users to identify the critical load at which typical cohesive and adhesive coating failure occurs. It provides a superior tool to quantitatively evaluate and compare the intrinsic quality of the coating and the interfacial integrity of the coating/substrate system for QCM.

The Nano, Micro or Macro modules of the NANOVEA Mechanical Tester all include ISO and ASTM compliant indentation, scratch and wear tester modes, providing the widest and most user friendly range of testing available in a single system. NANOVEA‘s unmatched range is an ideal solution for determining the full range of mechanical properties of thin or thick, soft or hard coatings, films and substrates, including hardness, Young’s modulus, fracture toughness, adhesion, wear resistance and many others.

In addition, an optional 3D non-contact profiler and AFM module are available for high resolution 3D imaging of indentation, scratch and wear track in addition to other surface measurements, such as roughness and warpage.

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The World’s Leading Micro Mechanical Tester

 

NOW THE WORLD'S LEADING

MICRO MECHANICAL TESTING

Prepared by

PIERRE LEROUX & DUANJIE LI, PhD

INTRODUCTION

Standard Vickers Micro Hardness Testers have usable load ranges from 10 to 2000 gram force (gf). Standard Vickers Macro Hardness Testers load from 1 to 50 Kgf. These instruments are not only very limited in range of loads but they are also inaccurate when dealing with rougher surfaces or low loads when indents become too small to be measured visually. These limitations are intrinsic to older technology and as a result, instrumented indentation is becoming the standard choice due to the higher accuracy and performance it brings.

With NANOVEA‘s world leading micro mechanical testing systems, Vickers hardness is automatically calculated from depth versus load data with the widest load range on a single module ever available (0.3 grams to 2 Kg or 6 grams to 40 Kg). Because it measures hardness from depth versus load curves, the NANOVEA Micro Module can measure any type of materials including very elastic ones. It also can provide not only Vickers hardness but also accurate elastic modulus and creep data in addition to other types of test such as scratch adhesion testing, wear, fatigue testing, yield strength and fracture toughness for a complete range of quality control data.

NOW THE WORLD'S LEADING MICRO MECHANICAL TESTING

In this applications note, it will be explained how the Micro Module has been designed to offer the world’s leading instrumented indentation and scratch testing. The Micro Module’s wide range testing capability is ideal for many applications. For example, the load range allows for accurate hardness and elastic modulus measurements of thin hard coatings and can then apply much higher loads to measure the adhesion of these same coatings.

MEASUREMENT OBJECTIVE

The capacity of the Micro Module is showcased with the NANOVEA CB500 Mechanical Tester by
performing both indentation and scratch tests with superior precision and reliability using a wide load range from 0.03 to 200 N.

NANOVEA

CB500

TEST CONDITIONS

A series (3×4, 12 indents in total) of Microindentations were performed on a standard steel sample using a Vickers indenter. The load and depth were measured and recorded for the complete indentation test cycle. The indentations were performed to different maximum loads ranging from 0.03 N to 200 N (0.0031 to 20.4 kgf) to showcase the capacity of the micro module in performing accurate indentation tests at different loads. It is worth noting that an optional load cell of 20 N is also available to provide 10 times higher resolution for tests in the lower load range from 0.3 gf up to 2 kgf.

Two scratch tests were performed using the Micro Module with linearly increased load from 0.01 N to 200 N and from 0.01 N to 0.5 N, respectively, using conico-spherical diamond stylus with tip radius of 500 μm and 20 μm.

Twenty Microindentation tests were carried out on the steel standard sample at 4 N showcasing the superior repeatability of the Micro Module’s results that contrast the performance of conventional Vickers hardness testers.

*microindenter on the steel sample

TEST PARAMETERS

of the Indentation Mapping

MAPPING: 3 BY 4 INDENTS

RESULTS AND DISCUSSION

The new Micro Module has a unique combination of Z-motor, high-force load cell and a high precision capacitive depth sensor. The unique utilization of independent depth and load sensors ensures high accuracy under all conditions.

Conventional Vickers hardness tests use diamond square-based pyramid indenter tips that create square shaped indents. By measuring the average length of the diagonal, d, the Vickers hardness can be calculated.

In comparison, the instrumented indentation technique used by NANOVEA‘s Micro Module directly measures the mechanical properties from indentation load & displacement measurements. No visual observation of the indent is required. This eliminates user or computer image processing errors in determining the d values of the indentation. The high accuracy capacitor depth sensor with a very low noise level of 0.3 nm can accurately measure the depth of indents that are difficult or impossible to be measured visually under a microscope with traditional Vickers hardness testers.

In addition, the cantilever technique used by competitors applies the normal load on a cantilever beam by a spring, and this load is in turn applied on the indenter. Such a design has a flaw in case a high load is applied – the cantilever beam cannot provide sufficient structural stiffness, leading to deformation of the cantilever beam and in turn misalignment of the indenter. In comparison, the Micro Module applies the normal load via the Z-motor acting on the load cell and then the indenter for direct load application. All the elements are vertically aligned for maximum stiffness, ensuring repeatable and accurate indentation and scratch measurements in the full load range.

Close-up view of the new Micro Module

INDENTATION FROM 0.03 TO 200 N

The image of the indentation map is displayed in FIGURE 1. The distance between the two adjacent indents above 10 N is 0.5 mm, while the one at lower loads is 0.25 mm. The high-precision position control of the sample stage allows users to select the target location for mechanical properties mapping. Thanks to the excellent stiffness of the micro module due to the vertical alignment of its components, the Vickers indenter keeps a perfect vertical orientation as it penetrates into the steel sample under a load of up to 200 N (400 N optional). This creates impressions of a symmetric square shape on the sample surface at different loads.

The individual indentations at different loads under the microscope are displayed alongside of the two scratches as shown in FIGURE 2, to showcase the capacity of the new micro module in performing both indentation and scratch tests in a wide load range with a high precision. As shown in the Normal Load vs. Scratch Length plots, the normal load increases linearly as the conico-spherical diamond stylus slides on the steel sample surface. It creates a smooth straight scratch track of progressively increased width and depth.

FIGURE 1: Indentation Map

Two scratch tests were performed using the Micro Module with linearly increased load from 0.01 N to 200 N and from 0.01 N to 0.5 N, respectively, using conico-spherical diamond stylus with tip radius of 500 μm and 20 μm.

Twenty Microindentation tests were carried out on the steel standard sample at 4 N showcasing the superior repeatability of the Micro Module’s results that contrast the performance of conventional Vickers hardness testers.

A: INDENTATION AND SCRATCH UNDER THE MICROSCOPE (360X)

B: INDENTATION AND SCRATCH UNDER THE MICROSCOPE (3000X)

FIGURE 2: Load vs Displacement plots at different maximum loads.

The load-displacement curves during the indentation at different maximum loads are shown in FIGURE 3. The hardness and elastic modulus are summarized and compared in FIGURE 4. The steel sample exhibits a constant elastic modulus throughout the test load ranging from 0.03 to 200 N (possible range 0.003 to 400 N), resulting in an average value of ~211 GPa. The hardness exhibits a relatively constant value of ~6.5 GPa measured under a maximum load above 100 N. As the load decreases to a range of 2 to 10 N, an average hardness of ~9 GPa is measured.

FIGURE 3: Load vs Displacement plots at different maximum loads.

FIGURE 4: Hardness and Young’s modulus of the steel sample measured by different maximum loads.

INDENTATION FROM 0.03 TO 200 N

Twenty Microindentation tests were performed at 4N maximum load. The load-displacement curves are displayed in FIGURE 5 and the resulting Vickers hardness and Young’s modulus are shown in FIGURE 6.

FIGURE 5: Load-displacement curves for microindentation tests at 4 N.

FIGURE 6: Vickers hardness and Young’s Modulus for 20 microindentations at 4 N.

The load-displacement curves demonstrate the superior repeatability of the new Micro Module. The steel standard possesses a Vickers hardness of 842±11 HV measured by the new Micro Module, compared to 817±18 HV as measured using the conventional Vickers hardness tester. The small standard deviation of the hardness measurement ensures reliable and reproducible characterization of mechanical properties in the R&D and quality control of materials in both the industrial sector and academia research.

In addition, a Young’s Modulus of 208±5 GPa is calculated from the load-displacement curve, which is not available for conventional Vickers hardness tester due to the missing depth measurement during the indentation. As load decrease and the size of the indent decreases, the NANOVEA Micro Module advantages in terms of repeatability compare to Vickers Hardness Testers increase until it is no longer possible to measure the indent through visual inspection.

The advantage of measuring depth to calculate hardness also becomes evident when dealing with rougher or when samples are more difficult to observe under standard microscopes provided on Vickers Hardness Testers.

CONCLUSION

In this study, we have shown how the new world leading NANOVEA Micro Module (200 N range) performs unmatched reproducible and precise indentation and scratch measurements under a wide load range from 0.03 to 200 N (3 gf to 20.4 kgf). An optional lower range Micro Module can provide testing from 0.003 to 20 N (0.3 gf to 2 kgf). The unique vertical alignment of the Z-motor, high-force load cell and depth sensor ensures maximum structural stiffness during measurements. The indentations measured at different loads all possess a symmetric square shape on the sample surface. A straight scratch track of progressively increased width and depth is created in the scratch test of a 200 N maximum load.

The new Micro Module can be configured on the PB1000 (150 x 200 mm) or the CB500 (100 x 50 mm) mechanical base with a z motorization (50 mm range). Combined with a powerful camera system (position accuracy of 0.2 microns) the systems provide the best automation and mapping capabilities on the market. NANOVEA also offers a unique patented function (EP No. 30761530) which allows verification and calibration of Vickers indenters by performing a single indent across the full range of loads. In contrast, standard Vickers Hardness Testers can only provide calibration at one load.

Additionally, the NANOVEA software enables a user to measure the Vickers hardness via the traditional method of measuring the indent diagonals if needed (for ASTM E92 & E384). As shown, in this document, depth versus load hardness testing (ASTM E2546 and ISO 14577) performed by a NANOVEA Micro Module is precise and reproducible compared to Traditional Hardness Testers. Especially for samples that cannot be observed/measured with a microscope.

In conclusion, the higher accuracy and repeatability of the Micro Module design with its broad range of loads and tests, high automation and mapping options renders the traditional Vickers hardness testers obsolete. But likewise with scratch and micro scratch testers still currently offered but designed with flaws in the 1980’s.

The continuous development and improvement of this technology makes NANOVEA a world leader in micro mechanical testing.

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Creep Deformation of Polymers using Nanoindentation

Creep Deformation of Polymers using Nanoindentation

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CREEP DEFORMATION

OF POLYMERS USING NANOINDENTATION

Prepared by

DUANJIE LI, PhD

INTRODUCTION

As viscoelastic materials, polymers often undergo a time-dependent deformation under a certain applied load, also known as creep. Creep becomes a critical factor when the polymeric parts are designed to be exposed to continuous stress, such as structural components, joins and fittings, and hydrostatic pressure vessels.

IMPORTANCE OF CREEP MEASUREMENT FOR POLYMERS

The inherent nature of viscoelasticity plays a vital role in the performance of polymers and directly influences their service reliability. The environmental conditions such as loading and temperature affect the creep behavior of the polymers. Creep failures often occur due to the lack of alertness of the time-dependent creep behavior of the polymer materials used under specific service conditions. As a result, it is important to develop a reliable and quantitative test of the viscoelastic mechanical behaviors of the polymers. The Nano module of the NANOVEA Mechanical Testers applies the load with a high-precision piezo and directly measures the evolution of force and displacement in situ. The combination of accuracy and repeatability makes it an ideal tool for creep measurement.

MEASUREMENT OBJECTIVE

In this application, we showcased that
the NANOVEA PB1000 Mechanical Tester
in Nanoindentation mode is an ideal tool
for studying viscoelastic mechanical properties
including hardness, Young’s modulus
and creep of polymeric materials.

NANOVEA

PB1000

TEST CONDITIONS

Eight different polymer samples were tested by nanoindentation technique using the NANOVEA PB1000 Mechanical Tester. As the load linearly increased from 0 to 40 mN, the depth progressively increased during the loading stage. The creep was then measured by the change of indentation depth at the maximum load of 40 mN for 30 s.

MAXIMUM LOAD 40 mN
LOADING RATE
80 mN/min
UNLOADING RATE 80 mN/min
CREEP TIME
30 s

INDENTER TYPE

Berkovich

Diamond

*setup of the nanoindentation test

RESULTS & DISCUSSION

The load vs displacement plot of the nanoindentation tests on different polymer samples is shown in FIGURE 1 and the creep curves are compared in FIGURE 2. The hardness and Young’s modulus are summarized in  FIGURE 3, and the creep depth is shown in FIGURE 4. As an examples in FIGURE 1, the AB, BC and CD portions of the load-displacement curve for the nanoindentation measurement represent the loading, creep and unloading processes, respectively.

Delrin and PVC exhibit the highest hardness of 0.23 and 0.22 GPa, respectively, while LDPE possesses the lowest hardness of 0.026 GPa among the tested polymers. In general, the harder polymers show lower creep rates. The softest LDPE has the highest creep depth of 798 nm, compared to ~120 nm for Delrin.

The creep properties of the polymers are critical when they are used in structural parts. By precisely measuring the hardness and creep of the polymers, a better understanding of the time-dependent reliability of the polymers can be obtained. The creep, change of the displacement at a given load, can also be measured at different elevated temperatures and humidity using the NANOVEA PB1000 Mechanical Tester, providing an ideal tool to quantitatively and reliably measure the viscoelastic mechanical behaviors of polymers
in the simulated realistic application environment.

FIGURE 1: The load vs displacement plots
of different polymers.

FIGURE 2: Creeping at a maximum load of 40 mN for 30 s.

FIGURE 3: Hardness and Young’s modulus of the polymers.

FIGURE 4: Creep depth of the polymers.

CONCLUSION

In this study, we showcased that the NANOVEA PB1000
Mechanical Tester measures the mechanical properties of different polymers, including hardness, Young’s modulus and creep. Such mechanical properties are essential in selecting the proper polymer material for intended applications. Derlin and PVC exhibit the highest hardness of 0.23 and 0.22 GPa, respectively, while LDPE possesses the lowest hardness of 0.026 GPa among the tested polymers. In general, the harder polymers exhibit lower creep rates. The softest LDPE shows the highest creep depth of 798 nm, compared to ~120 nm for Derlin.

The NANOVEA Mechanical Testers provide unmatched multi-function Nano and Micro modules on a single platform. Both the Nano and Micro modules include scratch tester, hardness tester and wear tester modes, providing the wildest and most user-friendly range of testing available on a single system.

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Multiphase Material using Nanoindentation NANOVEA

Metallurgy Study of Multiphase Material using Nanoindentation

Metallurgy Study of Multiphase Material using Nanoindentation

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METALLURGY STUDY
OF MULTIPHASE MATERIAL

USING NANOINDENTATION

Prepared by

DUANJIE LI, PhD & ALEXIS CELESTIN

INTRODUCTION

Metallurgy studies the physical and chemical behavior of metallic elements, as well as their intermetallic compounds and alloys. Metals that undergo working processes, such as casting, forging, rolling, extrusion and machining, experience changes in their phases, microstructure and texture. These changes result in varied physical properties including hardness, strength, toughness, ductility, and wear resistance of the material. Metallography is often applied to learn the formation mechanism of such specific phases, microstructure and texture.

MPORTANCE OF LOCAL MECHANICAL PROPERTIES FOR MATERIALS DESIGN

Advanced materials often have multiple phases in a special microstructure and texture to achieve desired mechanical properties for target applications in industrial practice. Nanoindentation is widely applied to measure the mechanical behaviors of materials at small scales i ii. However, it is challenging and time-consuming to precisely select specific locations for indentation in a very small area. A reliable and user-friendly procedure of nanoindentation testing is in demand to determine the mechanical properties of different phases of a material with high precision and timely measurements.

MEASUREMENT OBJECTIVE

In this application, we measure mechanical properties of a multiphase metallurgical sample using the Most Powerful Mechanical Tester: the NANOVEA PB1000.

Here, we showcase the capacity of the PB1000 in performing nanoindentation measurements on multiple phases (grains) of a large sample surface with high precision and user friendliness using our Advanced Position Controller.

NANOVEA

PB1000

TEST CONDITIONS

In this study, we use a metallurgical sample with multiple phases. The sample had been polished to a mirror-like surface finish before the indentation tests. Four phases have been identified in the sample, namely PHASE 1, PHASE 2, PHASE 3 and PHASE 4 as shown below.

The Advanced Stage Controller is an intuitive sample navigation tool which automatically adjusts the speed of sample movement under the optical microscope based on position of the mouse. The further the mouse is away from the center of field of view, the faster the stage moves toward the mouse’s direction. This provides a user-friendly method to navigate the entire sample surface and select the intended location for mechanical testing. The coordinates of the test locations are saved and numbered, along with their individual test setups, such as loads, loading/unloading rate, number of tests in a map, etc. Such a test procedure allows users to examine a large sample surface for specific areas of interest for indentation and perform all the indentation tests at different locations in one time, making it an ideal tool for mechanical testing of metallurgical samples with multiple phases.

In this study, we located the specific phases of the sample under the optical microscope integrated in the NANOVEA Mechanical Tester as numbered on FIGURE 1. The coordinates of the selected locations are saved, followed by automatic nanoindentation tests all at once under the test conditions summarized below

FIGURE 1: SELECTING NANOINDENTATION LOCATION ON THE SAMPLE SURFACE.
RESULTS: NANOINDENTATIONS ON DIFFERENT PHASES

The indentations at the different phases of the sample are displayed below. We demonstrate that the excellent position control of the sample stage in the NANOVEA Mechanical Tester allows users to precisely pinpoint the target location for mechanical properties testing.

The representative load-displacement curves of the indentations are shown in FIGURE 2, and the corresponding hardness and Young’s Modulus calculated using Oliver and Pharr Methodiii are summarized and
compared in
FIGURE 3.


The
PHASES 1, 2, 3 and 4 possess an average hardness of ~5.4, 19.6, 16.2 and 7.2 GPa, respectively. The
relatively small size for
PHASES 2 contributes to its higher standard deviation of the hardness and Young’s
Modulus values.

FIGURE 2: LOAD-DISPLACEMENT CURVES
OF THE NANOINDENTATIONS

FIGURE 3: HARDNESS & YOUNG’S MODULUS OF DIFFERENT PHASES

CONCLUSION

In this study, we showcased the NANOVEA Mechanical Tester performing nanoindentation measurements on multiple phases of a large metallurgical sample using the Advanced Stage Controller. The precise position control allows users to easily navigate a large sample surface and directly select the areas of interest for nanoindentation measurements.

The location coordinates of all the indentations are saved and then performed consecutively. Such a test procedure makes measurement of the local mechanical properties at small scales, e.g. the multi-phase metal sample in this study, substantially less time-consuming and more user friendly. The hard PHASES 2, 3 and 4 improve the mechanical properties of the sample, possessing an average hardness of ~19.6, 16.2 and 7.2 GPa, respectively, compared to ~5.4 GPa for PHASE 1.

The Nano, Micro or Macro modules of the instrument all include ISO and ASTM compliant indentation, scratch and wear tester modes, providing the widest and most user friendly range of testing available in a single system. NANOVEA‘s unmatched range is an ideal solution for determining the full range of mechanical properties of thin or thick, soft or hard coatings, films and substrates, including hardness, Young’s modulus, fracture toughness, adhesion, wear resistance and many others.

i Oliver, W. C.; Pharr, G. M., Journal of Materials Research., Volume 19, Issue 1, Jan 2004, pp.3-20
ii Schuh, C.A., Materials Today, Volume 9, Issue 5, May 2006, pp. 32–40
iii Oliver, W. C.; Pharr, G. M., Journal of Materials Research, Volume 7, Issue 6, June 1992, pp.1564-1583

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DMA Frequency Sweep on Polymer Using Nanoindentation

DMA Frequency Sweep on Polymer Using Nanonindentation

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DMA FREQUENCY SWEEP

ON POLYMER USING NANOINDENTATION

Prepared by

Duanjie Li, PhD

INTRODUCTION

IMPORTANCE OF DMA FREQUENCY SWEEP TEST

The changing frequency of the stress often leads to variations in the complex modulus, which is a critical mechanical property of polymers. For example, tires are subjected to cyclical high deformations when vehicles are running on the road. The frequency of the pressure and deformation changes as the car accelerates to higher speeds. Such a change can result in variation in the viscoelastic properties of the tire, which are important factors in the car performance. A reliable and repeatable test of the viscoelastic behavior of polymers at different frequencies is in need. The Nano module of the NANOVEA Mechanical Tester generates sinusoidal load by a high precision piezo actuator and directly measures the evolution of force and displacement using ultrasensitive load cell and capacitor. The combination of easy setup and high accuracy makes it an ideal tool for DMA frequency sweep.

Viscoelastic materials exhibit both viscous and elastic characteristics when undergoing deformation. Long molecular chains in polymer materials contribute to their unique viscoelastic properties, i.e. a combination of the characteristics of both elastic solids and Newtonian fluids. Stress, temperature, frequency and other factors all play roles in the viscoelastic properties. Dynamic Mechanical Analysis, also known as DMA, studies the viscoelastic behavior and complex modulus of the material by applying a sinusoidal stress and measuring the change of strain.

MEASUREMENT OBJECTIVE

In this application, we study viscoelastic properties of a polished tire sample at different DMA frequencies using the Most Powerful Mechanical Tester, NANOVEA PB1000, in Nanoindentation mode.

NANOVEA

PB1000

TEST CONDITIONS

FREQUENCIES (Hz):

0.1, 1.5, 10, 20

CREEP TIME AT EACH FREQ.

50 sec

OSCILLATION VOLTAGE

0.1 V

LOADING VOLTAGE

1 V

indenter type

Spherical

Diamond | 100 μm

RESULTS & DISCUSSION

The DMA frequency sweep at the maximum load allows a fast and simple measurement on the viscoelastic characteristics of the sample at different loading frequencies in one test. The phase shift and the amplitudes of the load and displacement waves at different frequencies can be used to calculate a variety of fundamental material viscoelastic properties, including Storage Modulus, Loss Modulus and Tan (δ) as summarized in the following graphs. 

Frequencies of 1, 5, 10 and 20 Hz in this study, correspond to speeds of about 7, 33, 67 and 134 km per hour. As the test frequency increases from 0.1 to 20 Hz, it can be observed that both Storage Modulus and Loss Modulus progressively increase. Tan (δ) decreases from ~0.27 to 0.18 as the frequency increases from 0.1 to 1 Hz, and then it gradually increases to ~0.55 when the frequency of 20 Hz is reached. DMA frequency sweep allows measuring the trends of Storage Modulus, Loss Modulus and Tan (δ), which provide information on the movement of the monomers and cross-linking as well as the glass transition of polymers. By raising the temperature using a heating plate during the frequency sweep, a more complete picture of the nature of the molecular motion under different test conditions can be obtained.

EVOLUTION OF LOAD & DEPTH

OF THE FULL DMA FREQUENCY SWEEP

LOAD & DEPTH vs TIME AT DIFFERENT FREQUENCIES

STORAGE MODULUS

AT DIFFERENT FREQUENCIES

LOSS MODULUS

AT DIFFERENT FREQUENCIES

TAN (δ)

AT DIFFERENT FREQUENCIES

CONCLUSION

In this study, we showcased the capacity of the NANOVEA Mechanical Tester in performing the DMA frequency sweep test on a tire sample. This test measures the viscoelastic properties of the tire at different frequencies of stress. The tire shows increased storage and loss modulus as the loading frequency increases from 0.1 to 20 Hz. It provides useful information on the viscoelastic behaviors of the tire running at different speeds, which is essential in improving the performance of tires for smoother and safer rides. The DMA frequency sweep test can be performed at various temperatures to mimic the realistic working environment of the tire under different weather.

In the Nano Module of the NANOVEA Mechanical Tester, the load application with the fast piezo is independent from the load measurement done by a separate high sensitivity strain gage. This gives a distinct advantage during DMA since the phase between depth and load is measured directly from the data collected from the sensor. The calculation of phase is direct and does not need mathematical modeling that adds inaccuracy to the resulting loss and storage modulus. This is not the case for a coil-based system.

In conclusion, DMA measures loss and storage modulus, complex modulus and Tan (δ) as a function of contact depth, time and frequency. Optional heating stage allows determination of materials phase transition temperature during DMA. The NANOVEA Mechanical Testers provide unmatched multi-function Nano and Micro modules on a single platform. Both the Nano and Micro modules include scratch tester, hardness tester and wear tester modes, providing the widest and most user friendly range of testing available on a single module.

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Microparticles: Compression Strength and Micro Indentation by Testing Salts

Microparticles: Compression Strength & Micro Indentation by Testing Salts

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MICROPARTICLES

COMPRESSION STRENGTH & MICRO INDENTATION
BY TESTING SALTS​

Author:
Jorge Ramirez

Revised by:
Jocelyn Esparza

INTRODUCTION

Compression strength has become vital to quality control measurement in developing and improving new and existing microparticles and micro features (pillars and spheres) seen today. Microparticles have various shapes, sizes and can be developed from ceramics, glass, polymers, and metals. Uses include drug delivery, food flavor enhancement, concrete formulations among many others. Controlling the mechanical properties of microparticles or microfeatures are critical for their success and requires the ability to quantitatively characterize their mechanical integrity  

IMPORTANCE OF DEPTH VERSUS LOAD COMPRESSION STRENGTH

Standard compressive measurement instruments are not capable of low loads and fail to provide adequate depth data for microparticles. By using Nano or Microindentation, the compression strength of nano or microparticles (soft or hard) can be accurately and precisely measured.  

MEASUREMENT OBJECTIVE

In this application note we measure  the compression strength of salt with the NANOVEA Mechanical Tester in micro indentation mode.

NANOVEA

CB500

TEST CONDITIONS

maximum force

30 N

loading rate

60 N/min

unloading rate

60 N/min

indenter type

Flat Punch

Steel | 1mm Diameter

Load vs depth curves

Results & Discussion

Height, failure force and strength for Particle 1 and Particle 2

Particle failure was determined to be the point where the initial slope of the force vs. depth curve began to noticeably decrease.This behavior shows the material has reached a yield point and is no longer able to resist the compressive forces being applied. Once the yield point is surpassed, the indentation depth begins to exponentially increase for the duration of the loading period. These behaviors can be seen in Load vs Depth Curves for both samples.

CONCLUSION

In conclusion, we have shown how the NANOVEA Mechanical Tester in micro indentation mode is a great tool for compression strength testing of microparticles. Although the particles tested are made of the same material, it is suspected that the different failure points measured in this study were likely due to pre-existent micro cracks in the particles and varying particle sizes. It should be noted that for brittle materials, acoustic emission sensors are available to measure the beginning of crack propagation during a test.


The
NANOVEA Mechanical Tester offers depth displacement resolutions down to the sub nanometer level,
making it a great tool for the study of very fragile micro particles or features as well. For soft and fragile
materials, loads down to 0.1mN are possible with our nano indentation module

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Ceramics: Nanoindentation Fast Mapping for Grain Detection

 
 
 

INTRODUCTION


Nanoindentation has become a widely applied technique for measuring mechanical behaviors of materials at small scalesi ii. The high-resolution load-displacement curves from a nanoindentation measurement can provide a variety of physicomechanical properties, including hardness, Young’s modulus, creeping, fracture toughness and many others.


Importance of Fast Mapping Indentation

One significant bottleneck for further popularization of the nanoindentation technique is time consumption. A mechanical property mapping by conventional nanoindentation procedure can easily take hours which hinders the application of the technique in mass production industries, such as semiconductor, aerospace, MEMS, consumer products such as ceramic tiles and many others.

Fast mapping can prove to be essential in the ceramic tile manufacturing industry, Hardness and Young’s modulus mappings across a single ceramic tile can present a distribution of data that indicates how homogeneous the surface is. Softer regions on a tile can be outlined in this mapping and show locations more prone to failure from physical impacts that happen on a day to day basis in someone’s residence. Mappings can be made on different types of tiles for comparative studies and on a batch of similar tiles to measure tile consistency in a quality control processes. The combination of measurements setups can be extensive as well as accurate and efficient with the fast mapping method.


MEASUREMENT OBJECTIVE


In this study, the Nanovea Mechanical Tester, in FastMap mode is used to map the mechanical property of a floor tile at high speeds. We showcase the capacity of the Nanovea Mechanical Tester in performing two fast nanoindentation mappings with high precision and reproducibility.


Test Conditions

The Nanovea Mechanical Tester was used to perform a series of nanoindentations with the FastMap Mode on a floor tile using a Berkovich indenter. The test parameters are summarized below for the two indent matrices created.


Table 1:  Test parameter summary.
 
The tested sample.


 

RESULTS & DISCUSSION 



Figure 1:  2D and 3D view of 625-indent hardness mapping.



Figure 2:  Micrograph of 625-indent matrix showcasing grain.


A 625-indent matrix was conducted on a 0.20mm2 area with a large visible grain present. This grain (Figure 2) had an average hardness lower than the overall surface of the tile. The Nanovea Mechanical Software allows the user to see the hardness distribution map in 2D and 3D mode which are depicted in Figure 1. Using the high-precision position control of the sample stage, the software allows users to target areas such as these for in depth mechanical properties mapping.



Figure 3:  2D and 3D view of 1600-indent hardness mapping.




Figure 4:  Micrograph of 1600-indent matrix.


A 1600-indent matrix was also created on the same tile to measure the homogeneity of the surface. Here again the user has the ability to see the hardness distribution in 3D or 2D mode (Figure 3) as well as the microscope image of the indented surface. Based on the hardness distribution presented, it can be concluded that the material is porous due to the even scattering of high and low hardness data points.

Compared to conventional nanoindentation procedures, FastMap mode in this study is substantially less time-consuming and more cost-effective. It enables speedy quantitative mapping of mechanical properties including Hardness and Young’s Modulus and provides a solution for grain detection and material consistency which is critical for quality control of a variety of materials in mass production.




CONCLUSION


In this study, we showcased the capacity of the Nanovea Mechanical Tester in performing speedy and precise nanoindentation mapping using FastMap mode. The mechanical property maps on the ceramic tile utilize the position control (with 0.2µm accuracy) of the stages and force module sensitivity to detect surface grains and measure homogeneity of a surface at high speed.

The test parameters used in this study were determined based on the size of the matrix and sample material. A variety of test parameters can be chosen to optimize the total indentation cycle time to 3 seconds per indent (or 30 seconds for every 10 indentations).

The Nano and Micro modules of the Nanovea Mechanical Tester all include ISO and ASTM compliant indentation, scratch and wear tester modes, providing the widest and most user-friendly range of testing available in a single system. Nanovea's unmatched range is an ideal solution for determining the full range of mechanical properties of thin or thick, soft or hard coatings, films and substrates, including hardness, Young’s Modulus, fracture toughness, adhesion, wear resistance and many others.

In addition, optional 3D non-contact profiler and AFM Module are available for high resolution 3D imaging of indentation, scratch and wear track in addition to other surface measurements such as roughness.

 

Author: Duanjie Li, PhD
Revised by Pierre Leroux & Jocelyn Esparza

Improve Mining Procedures With Microindendation

Improve Mining Procedures With Microindendation

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MICROINDENTATION RESEARCH AND QUALITY CONTROL

Rock mechanics is the study of the mechanical behavior of rock masses and is applied in mining, drilling, reservoir production, and civil construction industries. Advanced instrumentation with precise measurement of mechanical properties allows for part and procedure improvement within these industries. Successful quality control procedures are ensured by understanding rock mechanics at the micro scale.

Microindentation is a crucial tool used for rock mechanics related studies. These techniques advance excavation techniques by providing further understanding of rock mass properties. Microindentation is used to improve drill heads which improve mining procedures. Microindentation has been used to study chalk and powder formation from minerals. Microindentation studies can include hardness, Young’s modulus, creep, stress-strain, fracture toughness, and compression with a single instrument.
 
 

MEASUREMENT OBJECTIVE

In this application the Nanovea mechanical tester measures the Vickers hardness (Hv), Young’s modulus, and fracture toughness of a mineral rock sample. The rock is made up of biotite, feldspar and quartz which form the standard granite composite. Each is tested separately.

 

RESULTS AND DISCUSSION

This section includes a summary table that compares the main numerical results for the different samples, followed by the full result listings, including each indentation performed, accompanied by micrographs of the indentation, when available. These full results present the measured values of Hardness and Young’s modulus as the penetration depth (Δd) with their averages and standard deviations. It should be considered that large variation in the results can occur in the case that the surface roughness is in the same size range as the indentation.


Summary table of main numerical results for Hardness and Fracture Toughness

 

CONCLUSION

The Nanovea mechanical tester demonstrates reproducibility and precise indentation results on the hard surface of mineral rock. Hardness and Young’s modulus of each material forming the granite was measured directly from depth versus load curves. The rough surface meant testing at higher loads that may have caused micro cracking. Micro cracking would explain some of the variations seen in measurements. Cracks were not perceivable through standard microscopy observation because of a rough sample surface. Therefore, it is not possible to calculate traditional fracture toughness numbers that requires cracks length measurements. Instead, we used the system to detect initiation of cracks through the dislocations in the depth versus load curves while increasing loads.

Fracture threshold loads were reported at loads where failures occurred. Unlike traditional fracture toughness tests that simply measure crack length, a load is obtained at which threshold fracture starts. Additionally, the controlled and closely monitored environment allows the measurement of hardness to use as a quantitative value for comparing a variety of samples.

Biological Tissue Hardness Evaluation using Nanoindentation

Importance of Nanoindentation for Biomaterials

Traditional mechanical tests (hardness, adhesion, compression, puncture, yield strength, etc.) require greater precision and reliability in today’s quality control environments with a wide range of advanced materials from tissues to brittle materials. Traditional mechanical instrumentation fails to provide the sensitive load control and resolution required for advanced materials. The challenges associated with biomaterials require developing mechanical tests capable of accurate load control on extremely soft materials. These materials require very low sub mN testing loads with large depth range to ensure proper property measurement. In addition, many different mechanical test types can be performed on a single system allowing for greater functionality. This provides a range of important measurements on biomaterials including hardness, elastic modulus, loss and storage modulus, and creep in addition to scratch resistance and yield strength failure points.


Measurement Objective

In this application Nanovea’s mechanical tester in nanoindentation mode is used to study the hardness and elastic modulus of 3 separate areas of a biomaterial substitute on fat, light meat, and dark meat regions of prosciutto.

Nanoindentation is based on instrumented indentation standards ASTM E2546 and ISO 14577. It uses established methods where an indenter tip of known geometry is driven into a specific site of the test material with a controlled increasing normal load. When reaching a pre-set maximum depth, normal load is reduced until complete relaxation occurs. Load is applied by a piezo actuator and measured in a controlled loop with a high sensitivity load cell. During experiments the indenter position relative to the sample surface is monitored with a high precision capacitive sensor. The resulting load and displacement curves provide data specific to the mechanical nature of the tested material. Established models calculate quantitative hardness and modulus values with the measured data. Nanoindentation is suited to low load and penetration depth measurements at nanometer scales.


Results and Discussion

These tables below present measured values of hardness and Young’s modulus with averages and standard deviations. High surface roughness may cause large variations in the results due to small indentation size.



The fat area had about half the hardness of the meat areas. Meat treatment caused the darker meat area to be harder than the light meat area. Elastic modulus and hardness are in direct relation to mouth feel chewiness of the fat and meat areas. The fat and light meat area have creep continuing at a higher rate than the dark meat after 60 seconds.



Detailed Results – Fat




Detailed Results – Light Meat




Detailed Results – Dark Meat





Conclusion



In this application, Nanovea’s mechanical tester in nanoindentation mode reliably determined mechanical properties of the fat and meat areas while overcoming high sample surface roughness. This demonstrated the wide and unmatched capability of Nanovea’s mechanical tester. The system simultaneously provides precise mechanical property measurements on extremely hard materials and soft biological tissues. The load cell in closed loop control with the piezo table ensures precise measurement of hard or soft gel materials from 1 to 5kPa. Using the same system, it is possible to test biomaterials at higher loads up to 400N. Multi-cycle loading can be used for fatigue testing and yield strength information in each zone can be obtained using a flat cylindrical diamond tip. In addition, with Dynamic Mechanical Analysis (DMA), the viscoelastic properties loss and storage moduli can be evaluated with high accuracy using the closed loop load control. Tests at various temperatures and under liquids are also available on the same system. Nanovea’s mechanical tester continues to be the superior tool for biological and soft polymer/gel applications.

Wear and Scratch Evaluation of Surface Treated Copper Wire

Wear and Scratch Evaluation of Surface Treated Copper Wire

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Importance of Wear and Scratch Evaluation of Copper Wire

Copper has a long history of use in electric wiring since the invention of the electromagnet and telegraph. Copper wires are applied in a wide range of electronic equipment such as panels, meters, computers, business machines, and appliances thanks to its corrosion resistance, solderability, and performance at elevated temperatures up to 150°C. Approximately half of all mined copper is used for manufacturing electrical wire and cable conductors.

Copper wire surface quality is critical to application service performance and lifetime. Micro defects in wires may lead to excessive wear, crack initiation and propagation, decreased conductivity, and inadequate solderability. Proper surface treatment of copper wires removes surface defects generated during wire drawing improving corrosion, scratch, and wear resistance. Many aerospace applications with copper wires require controlled behavior to prevent unexpected equipment failure. Quantifiable and reliable measurements are needed to properly evaluate the wear and scratch resistance of the copper wire surface.


Measurement Objective

In this application we simulate a controlled wear process of different copper wire surface treatments. Scratch testing measures the load required to cause failure on the treated surface layer. This study showcases the Nanovea Tribometer and Mechanical Tester as ideal tools for evaluation and quality control of electric wires.


Test Procedure and Procedures

Coefficient of friction (COF) and wear resistance of two different surface treatments on copper wires (Wire A and Wire B) were evaluated by the Nanovea tribometer using a linear reciprocating wear module. An Al₂O₃ ball (6 mm diameter) is the counter material used in this application. The wear track was examined using Nanovea’s 3D non-contact profilometer. Test parameters are summarized in Table 1.

A smooth Al₂O₃ ball as a counter material was used as an example in this study. Any solid material with different shape and surface finish can be applied using a custom fixture to simulate the actual application situation.



Nanovea’s mechanical tester equipped with a Rockwell C diamond stylus (100 μm radius) performed progressive load scratch tests on the coated wires using micro scratch mode. Scratch test parameters and tip geometry are shown in Table 2.




Results and Discussion

Wear of copper wire: Figure 2 shows COF evolution of the copper wires during wear tests. Wire A shows a stable COF of ~0.4 throughout the wear test while wire B exhibits a COF of ~0.35 in the first 100 revolutions and progressively increases to ~0.4.



Figure 3 compares wear tracks of the copper wires after tests. Nanovea’s 3D non-contact profilometer offered superior analysis of the detailed morphology of wear tracks. It allows direct and accurate determination of the wear track volume by providing a fundamental understanding of the wear mechanism. Wire B’s surface has signi¬ficant wear track damage after a 600-revolution wear test. The profilometer 3D view shows the surface treated layer of Wire B removed completely which substantially accelerated the wear process. This left a flattened wear track on Wire B where copper substrate is exposed. This may result in significantly shortened lifespan of electrical equipment where Wire B is used. In comparison, Wire A exhibits relatively mild wear shown by a shallow wear track on the surface. The surface treated layer on Wire A did not remove like the layer on Wire B under the same conditions.







Scratch resistance of the copper wire surface: Figure 4 shows the scratch tracks on the wires after testing. The protective layer of Wire A exhibits very good scratch resistance. It delaminates at a load of ~12.6 N. In comparison, the protective layer of Wire B failed at a load of ~1.0 N. Such a significant difference in scratch resistance for these wires contributes to their wear performance, where Wire A possesses substantially enhanced wear resistance. The evolution of normal force, COF, and depth during the scratch tests shown in Fig. 5 provides more insight on coating failure during tests.






Conclusion



In this controlled study we showcased the Nanovea’s tribometer conducting quantitative evaluation of wear resistance for surface treated copper wires and Nanovea’s mechanical tester providing reliable assessment of copper wire scratch resistance. Wire surface treatment plays a critical role in the tribo-mechanical properties during their lifetime. Proper surface treatment on Wire A significantly enhanced wear and scratch resistance, critical in the performance and lifespan of electrical wires in rough environments. Nanovea’s tribometer offers precise and repeatable wear and friction testing using ISO and ASTM compliant rotative and linear modes, with optional high temperature wear, lubrication, and tribo-corrosion modules available in one pre-integrated system. Nanovea’s unmatched range is an ideal solution for determining the full range of tribological properties of thin or thick, soft or hard coatings, films, and substrates.

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