Pr flfi ˘ˇ ˝ - Zwick Roell Materials Testing Systems · · 2018-04-17The nano- and micro-scale of the ... • 3-axis stepper motor control as PCI-E plug ... segments can be programed

Product InformationZHN - Universal Nanomechanical Testing System

PI 9

01 2

.011

7

Range of application

The Universal Nanomechanical Tester ZHN is designed for the determination of hardness and elastic modu-lus of materials and coating systems. The nano- and micro-scale of the EN ISO 14577 are covered according to the standard (Instrumented indentation test for the determination of hardness and other materials para-meters for Metallic materials and layers). In addition the nanomechanical tester can also perform cyclical and indenteation tests superimposed with an oscillation. The nanomechanical tester is used as a: • Nanoindenter• Hardness tester• Micro scratch tester• Profilometer• Fatigue tester• Micro wear tester• Tribometer

Advantages/features

• Modern and intuitive software• Rigid frame structure with the axis of the indenter

exactly in the axis of movement (no tilting moment)• Extreme modularity because of:

- Exchangeable measurement heads for Fmax 2 N and 0.2 N

- Unique tandem-microscope (developed for the Aerospace) with 2 cameras, upgradeable up to 4 different magnifications

- Unique analysis routines that use sophisticated physical models and new contact mechanical findings

- Various sample holders, even with isolated head for measuring the contact resistance „indenter - specimen“

• Large working area with resolution of X-Y-Z table: - X-direction: 100 mm - Y-direction: 200 mm - Z-direction: 70 mm

• New design of housing for thermic and accoustic isolation

Housing for thermic and accoustic isolationZHN Nanoindenter (front view)

1


Concept

Modular design consisting of• 2-column load frame with central spindle drive,

precision guidance and granite base• Central motorized spindle drive and programmable

motorized XY stage• 3-axis stepper motor control as PCI-E plug• Tandem microscope with 2 cameras and LED

illumination (LED green)• Control electronics for machine and measuring head• Interchangeable measurement heads up to 2 N• Control and evaluation software InspektorX• SW modules for autofocus• SW module for the generation of a focused image

from a series of images

The diversity and flexibility of the test concept

The Universal Nano Mechanical Tester ZHN is the further development of the proven Nanoindenter tech-nology of ASMEC. It combines for the first time measu-ring heads for normal direction (nanoindenter principle) and lateral direction (scratch tester principle), that work completely independently and both with resolutions in the nanometer range. Thus, normal and a new type of lateral force-displacement curves can be measured at the same sample position and more material parame-ters can be obtained than before (see applications). Our lateral head is the first in the world to allow the mea-surement of lateral stiffness and wholly elastic lateral deformations of the sample.

The 2-column load frame with central spindle drive and a precision guide guarantees a stiffer frame structure. In addition, the axis of the indenter is exactly in the axis of movement (no tilting moment possible), and Abbe measurement errors are excluded. The stiffness of the machine is with more than 105 N/m so high that it no longer needs to be corrected, which significantly simpli-fies the calibration of the area function.

In contrast to most nanoindenters available on the mar-ket, both of the measuring heads work in compression mode as well as in tension mode, so that micro tensile tests are possible.

Features of the measurement head

The instrument can work under load control as well as displacement control in “open loop mode“ (only the ma-ximum force or displacement is controlled) or “closed loop mode” (every point of a curve is controled). The maximum data rate is 1000 points per second, so that very fast measurements are possible.

Sophisticated software is used for comfortable control of the instrument and swift programming of the measu-rement positions and a multitude of applications. One example is a unique module for the determination of stress-strain curves for metals from indentations with spheres. The measurement positions can be placed and configured simply by point-and-click.

Normal Force Unit (NFU)

• Easy mobility in normal direction and high stiffness in lateral direction by a double leaf spring system

• Robust construction• No “dead stop“ for the inductive sensors during

overload and therefore no damage possible• The shaft can carry substantial weights without

leaving the measuring range. This allows the use of any type of customer-specific measuring tips

Principle of the Normal Force Unit (NFU)

2


Optics

• A 50x objective where the optical path is led to two cameras through a beam splitter and a system of lenses

• Within the optical image it is possible to - define the measuring positions - measure the distances and circumferences - track and display the defined measuring positions per mouse click - control the illumination and other optical parameters - show scales and date/time information

• Omitting an objective revolver guarantees higher positioning accuracy and rapid magnification switches

• High quality images can be made also from surfaces with poor reflection like glass

• Autofocus function for the detection of the correct height for a sharp image

• Programmable automatic image generation at the measuring positions before and after measurement

• Focus series option for the generation of a focused image from a series of images

Fig. 3 and 4: Two very stiff sample holders for 5 smaller samples (Ø 24 mm) or one large sample (Ø 50 mm)

Fig. 5: A large variety of adapters for different measuring tips or test specimens is available

Accessories

Lateral Force Unit (LFU)

• Sample holder with the samples in the middle of vertically mounted pairs of leaf springs

• Easy mobility in lateral direction without vertical displacement of the sample and with sufficient stiffness in normal direction

• Force generation is decoupled from force measurement

• Application and measurement of lateral forces are possible without lateral movement of the sample

Fig. 1: Principle of the Lateral Force Unit (LFU)

Fig. 2: Second measurement head (LFU) with sample holder for 5 specimen

3


User interface

Control of the precision stagesThe device is designed for fully automatic measurement series with more than 1000 possible measuring posi-tions. The control software InspectorX gives a complete overview of the actual positions of the three precision stages and allows easy control with step sizes below 1 μm. When the sample is positioned under the micro-scope, an image of the sample surface is shown in the same window instead of the stage positions.

Definition of the measuring positionsAny number of positions can be programmed optionally in lines, columns, grids or in irregular arrangement. Unique features are the possibility to define different measuring procedures for every position and to auto-matically generate pictures with two different magni-fications before and after the measurement using the autofocus function. Comprehensive sample information can be assigned to every position and will be stored in data files.

Definition of the measuring procedure A large number of predefined applications that may be selected by a simple mouse click is available. Proce-dures (test cycles) with any number of load-unload segments can be programed and modified in a very flexible manner. Force or displacement, measuring time and data rate of a segment can be defined in “open loop mode” while in “closed loop mode” the number of data points and the dwell time per point may be set in addition.

Evaluation of measurement dataLoad-displacement curves or other data can be gra-phically presented, compared, averaged or exported in different formats (ASCII, EXCEL, BMP, WMF, etc.). Com-prehensive and flexible correction routines are available for data evaluation. Parameters for the analysis and the presentation of results can be stored in configuration files and exchanged among others.

The correction of data (zero point correction, thermal drift correction) as well as averaging of measuring curves with equal load and cycle can be carried out ma-nually or automatically, so that the results are eventually presented to the user in a table. Almost any number of data files can be read and analyzed simultaneously. Averaged and corrected curves can be stored automa-tically in seperate files.

4


Even more important than the signal-to-noise ratio for small depths of indentation is the accuracy of the correction functions for the tip shape as well as for the zero point (position of the surface) and thermal drift. The instrument software offers especially sophisticated correction routines and algorithms, whose quality was proven, for instance, by comparative measurements of the Physikalisch-Technische Bundesanstalt or du-ring inter-laboratory comparisons within two European projects.

Example (3) shows the determination of the area func-tion for a spherical indenter of 7.74 μm radius that was obtained with the help of two reference materials. The area is described by a fit function with up to 8 parame-ters.

Figure (4): Example for the zero point correction with an extrapolation method. Data from the time before con-tact (approach) can also be used for the correction.Fig. 1: Noise of the force signal at maximum force over 400 s

Fig. 2: Comparison of five load-displacement curves in fused silica

Fig. 3: Area function database for a spherical indenter

Fig. 4: Zero point correction with an extrapolation method

Precise measurements

The resolution values for force or displacement often given are only theoretical values, which are obtained from the bit number of the AD converter and the mea-surement range. However, they are not suitable for a comparison of different devices. Substantially more im-portant is the noise of the signals, which is also depen-dent on the environmental conditions. The ZHN shows an extremely high signal-to-noise ratio of six orders of magnitude (106), which allows measurements in four orders of magnitude (104) of the force.

In the shown example (1) the force was kept constant at the maximum force value of the instrument of 2000 mN over a period of 400 s. The average is 2000.001 mN and the standard deviation 2 μN. Example (2) compares six purely elastic measurements in fused silica with a rounded Berkovich tip at a maximum force of 0.5 mN and a data rate of 16 points per second. The difference in the depth of penetration of all curves is only about 1.5 nm, although different sample positions were used for the measurements.

5


Applications

Measurement of hardness and Young’s modulus according to ISO 14577The measurements are usually carried out with a Ber-kovich-Indenter under force control. Very fast measure-ments are possible, for instance with 6 s loading time, 5 s hold period and 3 s unloading time.

Fig. 2: Schema of the QCSM method

Fig. 3: 260 nm oxide coatings on sapphire and glass substrates, maximum force 18 mN. First point at (20 nm; 0.24 mN). The example clearly shows that the substrate influence can not be neglected for thin coatings. Only after extrapolation to zero indentation depth (right figure) you get the same modulus result for the same coating on different substrates.

Depth-dependent results with CSM/QCSM (Quasi Continuous Stiffness Measurement) The QCSM method is a new module developed by ASMEC, that allows measuring the contact stiffness of the sample not only with the help of an unload curve for one depth only, but for many points during the indenta-tion procedure. Thus hardness and indentation modulus can be determined depth-dependent at one and the same position of the sample. In addition, the sensitivity of the measurements will be raised in the small force range, so that stiffness values may be readily determi-ned even for very small forces and depths. With the QCSM module, loading is stopped for a short period of time (1 – 4 s) and the voltage for the piezoelectric ele-ment is overlaid with a sinusoidal oscillation. In contrast to other methods, the amplitude for force or displace-ment is not directly given. Amplitude and phase of the oscillations are determined with a lock-in filter.

Fig. 1: Test sequence with a Berkovich-Indenter

Measurable parameters:• Indentation hardness HIT (convertible to HV)• Martens hardness HM or HMs• Indentation modulus EIT (Young’s modulus)• Creep CIT or relaxation RIT

• Relation between elastic reverse deformation work and total mechanical work ηIT

More than 60 parameters can be defined.

Vickers hardnessThe Vickers hardness can be calculated using the indentation hardness. A comprehensive comparison between conventional Vickers hardness and indentation hardness for 20 different materials, carried out by the Federal Institute of Materials Research and Testing, has shown that the mean difference between HIT and HV is below 10% when the InspectorX algorithms are used, compared to 25 – 30% with other software packages.

[T. Chudoba, M. Griepentrog, International Journal ofMaterials Research 96 (2005) 11 1242 – 1246]

6


Fig. 1: Example: Stress-strain curve calculation with Neural Networks

Determination of height profilesScans of the surface can be carried out using the La-teral Force Unit (LFU) in X direction with nm resolution or only the XY-stages with μm resolution. Roughness parameters such as Ra, Rq or Rt can be determined.

Fig. 2: Scan perpendicularly to a scratch test, contact force 100 μN

Measurement of stress-strain curvesIn collaboration with the research center Karlsruhe a new method has been developed, that allows the deter-mination of the complete stress-strain curves of metals from indentations with a spherical indenter. It is based on the use of neural network for parameter identification and takes into account also kinematical hardening.

Micro scratch testsThe tests are typically carried out with spherical tips with a radius between 5 – 10 μm. Thereby the stress maximum (and the main damage) is mostly located in the layer and not in the substrate. Multiple scans of the surface are possible. The short scratch length of typi-cally 50 μm reduces the tip wear and the influence of surface roughness on the result.

Further applications

• Determination of the yield point from measurements with a spherical indenter

• Purely elastic measurements with a spherical indenter for the determination of Young’s modules of coatings, also of very thin hard layers beneath 50 nm

• Micro tensile tests• Fatigue measurements with small cycle numbers

General applications (examples)

• Coating development from soft (polymer) to hard (diamond like carbon)

• Determination of critical stresses for plastic deformation or crack formation

• Test of hard coatings for tools and as wear resisting layer

• Protective coatings on glasses• Varnish and Sol-Gel coatings• Automatic measurement of hardness distributions

across the section of a component• Nano coatings for sensors or MEMS/NEMS• Biological materials• Matrix effects in alloys• Ceramic materials and composites• Ion implanted surfaces• Failure analysis in microelectronics

Fig. 3: Scratch of a layer on Silicon, Fmax 500 mN

Micro wear testsOscillatory wear tests with amplitudes of up to 140 μm can be carried out.

7


All data at ambient temperature. All rights reserved.

Item number 1011428Dimensions (W x H x D) 640 x 790 x 390 mmWeight approx. 105 kgPower supply 230 V NFU Measurement head (Normal Force Unit)Item number 1016415 1016416 Maximum normal force (1 ± 2 N ± 0.2 NDigital force resolution ≤ 0.02 μN ≤ 0.002 μNNoise level force measurement ≤ 2 μN (2 (1σ at 8 Hz) ≤ 0.2 μN (1σ at 8 Hz)Maximum normal displacement (1 ± 200 μm Digital displacement resolution ≤ 0.002 nmNoise level displacement measurement ≤ 0.3 nm (1σ at 8 Hz) ≤ 0.2 nm (1σ at closed loop mode)LFU Measurement head (Lateral Force Unit)Item number 1021148Maximum normal force (1 ± 2 NDigital force resolution ≤ 0.02 μNNoise level force measurement ≤ 6 μNMaximum lateral displacement (1 ± 75 μm Digital displacement resolution ≤ 0.002 nmNoise level displacement measurement ≤ 0.5 nmDynamic Module (3

Max. oscillation frequency 300 HzMax. frequency for stiffness analysis 70 HzData acquisition rate 40 kHzMax. force amplitude of the oscillation > 100 mNOpticsTandem-microscope with two video cameras 1280 x 1024 Pixel; USB 3.0 connectionObjective lens 50 x (4 5 x (5

Working distance 0.38 mm / 10.8 mm (6 10.8 mmIllumination green LED, max. power 1 WOptical magnification on 23“ (camera 1 / camera 2) 1000 x / 3350 x 100 x / 335 xField of view (camera 1 / camera 2) 324 x 259 μm / 96 x 77 μm 3.2 x 2.6 mm / 0.97 x 0.77 mmPixel resolution (low/large) (camera 1 / camera 2) 254 nm / 76 nm 2540 nm / 760 nmSystem of X-Y-Z tableX-stage travel range 100 mm resolution 50 nmY-stage travel range 200 mm resolution 50 nmZ-stage travel range 70 mm resolution 10 nmMaximum sample size (X x Y x Z) 80 x 80 x 60 mmMaximal length of a scratch test 25 mm (7

(1 push and pull(2 106 signal-to-noise ratio(3 only together with QCSM software module(4 included in the scope of supply(5 5x objective lens with manual slider, item number: 1011431(6 Long distance objective lens, item number: 1016479(7 dependent on the evenness of the sample surface

Technical Data

8

Documents

Pr flfi ˘ˇ ˝ - Zwick Roell Materials Testing Systems · · 2018-04-17The nano- and micro-scale of the ... • 3-axis stepper motor control as PCI-E plug ... segments can be programed