ZHN – Universal Nanomechanical Testing System

A new dimension

The ZHN universal nanomechanical tester is used for comprehensive, mechanical characterization of thin layers or small surface areas with the necessary force and travel resolution. This includes measuring indentation hardness, indentation modulus, and Martens hardness to ISO 14577 (instrumented indentation testing).
ZHN nanoindenter

Key Advantages and Features

  • Modern software, with clearly structured design
  • Stiff frame design with indenter axis exactly in the movement axis (no tilting moment)
  • High degree of modularity provided by:
    • interchangeable measuring heads in normal (2 N / 0.2 N) and lateral directions, allowing realistic modeling of loading conditions
    • unique tandem optics (developed for space travel) with 2 cameras; can be expanded for up to 4 different magnifications
    • software structure features function / application modules for hardness and Young's modulus tests, scratch test, cyclic indentation test and indentation test with superimposed oscillation
  • Various specimen holders available, including holders with insulated specimen carriers for tip – specimen contact resistance measurement
  • Ample room in all directions, with precise step size and high resolution:
    • X-direction: 100 mm
    • Y-direction: 200 mm
    • Z-direction: 70 mm
  • New enclosure design with improved thermal and acoustic insulation

ZHN Applications

Hardness and Young's modulus to DIN EN ISO 14577

Hardness sequence with a Berkovich indenter

Hardness sequence with a Berkovich indenter

Measurement is typically performed with a Berkovich indenter with force control/ Fast measurements are possible, for example with 6-s load, 5-s hold time, and 3-s load removal.

  • Measurable values:
  • Indentation hardness HIT (revaluate in HV)
  • Martens hardness HM or HMs
  • Indentation modulus EIT (elasticity modulus)
  • Indentation creep CIT or relaxation RIT
  • Ratio of elastic deformation component to indentation energy nIT

A total of more than 60 values can be determined.

Vickers hardness

Vickers hardness comparison

Overview of relative deviation of Vickers hardness

Vickers hardness can be calculated from the indention hardness. A comprehensive study conducted by the Federal Institute for Materials Research and Testing (BAM) compared 20 materials using the conventional Vickers hardness method and the Vickers hardness method with values calculated with InspectorX algorithms and reevaluated using HIT. It showed a mean difference of < 10% vs. 25-30% with other software packages.

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

Depth-dependent measurements with QCSM module

QCSM - Quasi Continuous Stiffness Measurement

Schematic diagram of QCSM method sequence

The "Quasi-continuous Stiffness Measurement Method" is a module developed by ASMEC to enable sample contact stiffness to be determined using the unloading curve for many points during the indentation process rather than just for a depth. This allows depth-dependent determination of hardness and Young's modulus at one and the same sample location. In addition, measurement sensitivity at low forces is increased, enabling stiffness values to be determined for very low forces and indentation depths. With the QCSM module the load increase is paused for a short time (1-4 seconds) and a sinusoidal vibration is superimposed on the Piezo voltage. In contrast to other methods, the amplitude for force or displacement is not specified directly. Amplitude and vibration phase are determined using a lock-in filter.

Determination of stress-strain curve with neural networks

Neural network analysis with ZHN

Together with the Karlsruhe Research Center, a method has been developed that allows the entire stress-strain curve of metals to be determined from indentions made by spherical indenters. It is based on the use of neural networks to identify parameters and it also takes into consideration kinematic hardening.

Determination of strength values

Height profile measurement with ZHN

Scan perpendicular to a scratch test with a contact force of 100 µN

Surface scans can be performed with the lateral force unit (LFU) in the X direction with nm-resolution and also without LFU with the XY tables with μm resolution. Roughness values such as Ra, Rq or Rt are determined.

Micro wear tests

Micro wear tests with nanoindenter ZHN

Wear tests with a diamond sphere (radius of 55 μm) on a DLC coating Left row 1000 mN, right row 1500 mN load Amplitude 50 μm, measurement time 1800 s

Oscillating wear tests with amplitudes up to 140 μm can be performed.

Scratch and micro-scratch tests

Micro scratch test on silicon, Fmax 500 mN

Scratch test on a coating on silicon, Fmax 500 mN

The tests are typically performed with spherical tips with a radius between 5 and 10 μm. Stress maximum is most often in the coating and not in the substrate. Multiple scans of the surface is possible. The wear on the tip and impact of surface roughness is reduced by the small scratch length.

More applications with the ZHN

  • Determination of yield point from tests using a ball indenter (with ELASTICA additional software)
  • Purely elastic measurements with ball indenter to determine Young's modulus, including for very thin, hard films less than 50 nm thick
  • Micro tensile tests
  • Fatigue tests with low number of cycles
ZHN nanoindenter with LFU in use

A Testing Concept Offering Versatility and Flexibility

The ZHN universal nanomechanical tester is derived from ASMEC's proven nanoindenter technology. In this first-time development, two measuring heads are combined in the normal (nanodindenter principle) and lateral (scratch tester principle) directions, operating completely independently of each other with nanometer resolution. Lateral force-displacement curves can now be measured for the first time, allowing more material parameters to be obtained than was previously possible (see Typical Applications). This includes measurement of the lateral stiffness and purely elastic lateral deformation of the specimen.

The 2-column load frame features single central lead-screw drive and precision guidance, ensuring stiffer frame design, while the indenter axis is located exactly in the movement axis. No tilting moment occurs and Abbe errors are eliminated. Device stiffness is more than 106 N/m, eliminating the need for correction and greatly simplifying calibration of the area function.

In contrast to instruments by other manufacturers, both measuring heads operate in both tensile and compression directions, enabling indentation tests with a superimposed oscillation as well as cyclic fatigue tests.

Two patents cover the design of the ZHN‘s measuring heads:

NFU principle

Normal Force Unit (NFU)

Normal Force Unit (NFU)

  • Movement in the normal direction and high stiffness in the lateral direction thanks to the double leaf-spring system
  • Robust construction
  • No inductive sensor stop in the event of an overload and thus no damage
  • The shaft can bear heavier weights without leaving the measurement range Any kind of customer-specific probes can be easily used

LFU principle

Normal Force Unit (NFU)

Lateral force unit (LFU) image

  • Specimen grips with the specimen in the middle of perpendicularly positioned leaf springs
  • Can move easily in the lateral direction without a vertical change to the specimen position if sufficient stiffness in the normal direction exists
  • Force generation decoupled from the force measurement
  • Application and measurement of lateral forces without lateral movement possible
Details about ZHN nanoindenter optics

Modular Optics

You can increase the number of possible measurement methods and combine the ZHN with our different optic systems, such as an integrated AFM.

Optics – advantages and features

  • Determination of yield point from tests using a ball indenter (with ELASTICA additional software)
  • Purely elastic measurements with ball indenter to determine Young's modulus, including for very thin, hard films less than 50 nm thick
  • Micro tensile tests
  • Fatigue tests with low number of cycles

Various optic options

White light interferometer integrated in ZHN

White light interferometer integrated in ZHN

Optic options

As standard, the tandem microscope and 50x lens is included in the ZHN scope of supply A 50x lens with extended working distance is available as an option. Furthermore, there is a 5x lens or white light interferometer, which requires a manual slider.

Description

Item number

Long-distance lens 50x for tandem microscope for ZHN

  • Large working distance of 10.6 mm (otherwise 0.38 mm)
  • Additional charge, replaces the standard lens 50x

1016479

Lens 5x as second lens for tandem measuring microscope

  • Includes lens slider (manual) for changing between lenses
    With two different magnifications

1011431

SmartWLI white light interferometer

  • Optical profilometer as module for the ZHN with use of original ZHN optics
    With 2 cameras

Components:

  • Mirau lens 50x
  • Piezoelectric lens adjuster 400 μm (390 μm usable) for adjusting the height
  • SmartWLI software (without stitching module)
  • MountainsMap Imaging Topography software for 2.5D presentations and analysis
  • Includes lens slider (manual) for changing between lenses

1023953

Atomic force microscope (AFM)

Connecting an AFM to the ZHN

Nanoindentation and atomic force microscopy (AFM) can be combined in a single system to enable comprehensive, (semi) automated analysis. As a first step the atomic force microscope measures the surface roughness; this helps to define the minimum indentation depth. The specimen is then positioned under the nanoindenter to allow a mechanical analysis to be performed at the same location. In the final step this location can be moved back below the AFM to allow characterization and understanding of stress-induced properties such as material “pile-up” and “sink-in” or cracks around the indent. These effects may then influence the values obtained for hardness and Young's modulus.

Description

Item number

NaniteAFM C1000 atomic force microscope for standard measuring modes: static force (contact), dynamic force, force modulation, spreading resistance, phase contrast, magnetic force, electrostatic force

including:

  • Nanosurf C1000 control electronics (24/32-bit), including scripting interface for external control of system (COM Interface)
  • NaniteAFM measuring head (110 µm x 110µm x 20µm), with high-resolution cameras, top and side view
  • NaniteAFM measuring-head support - precision mount, for installation in Zwick/Roell nanoindenter
  • NaniteAFM Sample Stage 204 – additional system mount, including passive vibration insulation
  • NaniteAFM tool set
  • AFM specimen set for large measurement ranges
  • AFM measuring tips for static measuring modes (10 pieces)
  • AFM measuring tips for dynamic measuring modes (10 pieces)

1025985

Technical Overview

Below can be found technical data for the basic instrument with different lenses plus details of the measuring heads, for example digital resolution of force measurement.

Basic instrument with 50x lens

Description

Value

Item No.

1011428

Dimensions (H x W x D)

790 x 640 x 390

mm

Weight

approx. 105

kg

Voltage

230

V

Optics

Tandem microscope with two video cameras

1280 x 1024 pixels, USB 3.0 connection

Lens

50 x[1]

Working distance

0.38/10.6 [2]

mm

Lighting

Green LED, max. rating 1 W

Optical magnification to 23" (Camera 1/Camera 2)

1000 x/3350 x

Field of view (Camera 1/Camera 2)

324 x 259 μm/96 x 77 μm

Pixel resolution small/large (Camera 1/Camera 2)

254 nm/76 nm

Stage system

X-stage travel

200 mm, step size 50 nm

Y-stage travel

100 mm, step size 50 nm

Z-stage travel

70 mm, step size 10 nm

Maximum specimen size (X x Y x Z)

80 x 80 x 60

mm

Maximum length of a scratch test

25[3]

mm

  1. Included in the standard scope of supply
  1. Long-distance lens, see Optics Versions
  1. depending on smoothness of specimen surface

Basic instrument with 5x lens

Description

Value

Item No.

1011428

Dimensions (H x W x D)

790 x 640 x 390

mm

Weight

approx. 105

kg

Voltage

230

V

Optics

Tandem microscope with two video cameras

1280 x 1024 pixels, USB 3.0 connection

Lens

5 x[1]

Working distance

10.6

mm

Illumination

Green LED, max. rating 1 W

Optical magnification to 23" (Camera 1/Camera 2)

100 x/335 x

Field of view (Camera 1/Camera 2)

3.2 x 2.6 mm / 0.97 x 0.7 mm

Pixel resolution small/large (Camera 1/Camera 2)

2540 nm/760 nm

Stage system

X-stage travel

200 mm, step size 50 nm

Y-stage travel

100 mm, step size 50 nm

Z-stage travel

70 mm, step size 10 nm

Maximum specimen size (X x Y x Z)

80 x 80 x 60

mm

Maximum length of a scratch test

25[2]

mm

  1. 5x lens with manual displacement, see Optics Versions
  1. depending on smoothness of specimen surface

Technical data for normal measuring head

NFU (Normal Force Unit) measuring head

Item No.

1016415

1016416

Test load, max. (Fmax), normal[1]

Approx. 2

Approx. 0.2

N

Digital resolution, force measurement

≤0.02

≤0.002

μN

Background noise, force measurement

≤2[2]

≤0.2[2]

μN

Displacement, max.

approx. 200[1]

μm

Digital resolution, displacement measurement

≤0.002

≤0.002

nm

Background noise, displacement measurement (1 σ at 8 Hz)

≤0.3

≤0.3

nm

Background noise, displacement measurement (1 σ at closed loop module)

≤0.2

≤0.2

nm

Dynamic module [3]

Oscillation frequency, max.

300

300

Hz

Max. frequency for stiffness evaluation

70

25

Hz

Data acquisition rate

40

40

kHz

Max. force amplitude of oscillation

> 100

> 100

mN

  1. Compression and tensile
  1. Signal-to-noise ratio 106
  1. only in conjunction with the QCSM software module

Technical data for lateral measuring head

Lateral Measuring Head (LFU)

Description

Value

Item No.

1021148

Test load, max. (Fmax), lateral[1]

approx. 2

N

Digital resolution, force measurement

≤ 0.02

μN

Background noise, force measurement

≤ 6

μN

Travel, max.[1]

approx. 75

μm

Digital resolution, displacement measurement

≤ 0.002

nm

Background noise, displacement measurement

≤ 0.5

nm

  1. compression and tensile

Typical Applications

  • Coating development from soft (polymer) to hard (diamond-type coatings)
  • Determination of critical stresses for cracking or plastic deformation
  • Hard material coatings for tools and as scratch protection
  • Protective coatings on glass
  • Paints and sol-gel coatings
  • Automated measurement of hardness traverses on transverse cross-section
  • Nano coatings for sensors and MEMS/NEMS
  • Biological materials
  • Matrix effects in alloys (mapping)
  • Ceramic materials and composites
  • Ion-implanted surfaces
  • Damage analysis in microelectronics
  • Determination of surface load-bearing capacity (ELASTICA)

For Hot Specimens up to 400°C

The specimen heater can be installed in the ZHN instead of the standard specimen grip. It uses passive cooling and does not require any water supply. This enables the measuring of lateral forces and scratch testing without lateral force contribution
Hardness sequence with a Berkovich indenter

Hardness sequence with a Berkovich indenter

Measurement is typically performed with a Berkovich indenter with force control/ Fast measurements are possible, for example with 6-s load, 5-s hold time, and 3-s load removal.

  • Measurable values:
  • Indentation hardness HIT (revaluate in HV)
  • Martens hardness HM or HMs
  • Indentation modulus EIT (elasticity modulus)
  • Indentation creep CIT or relaxation RIT
  • Ratio of elastic deformation component to indentation energy nIT

A total of more than 60 values can be determined.

  • Determination of yield point from tests using a ball indenter (with ELASTICA additional software)
  • Purely elastic measurements with ball indenter to determine Young's modulus, including for very thin, hard films less than 50 nm thick
  • Micro tensile tests
  • Fatigue tests with low number of cycles

Characterization of coatings in the nano range

As coatings become thinner, the difficulty in determining their physical properties increases. The limits of previously tried and tested surface engineering techniques are encountered and results become unreliable. Available from Zwick is an efficient solution to this problem in the form of a tester developed specifically for characterizing mechanical surface properties in the micro and nano ranges.
LFU_01
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