Micro indentation hardness testing service

Micro Indentation Hardness Testing Service – Accredited ISO/IEC 17025 Micro‑Hardness and Material Characterization Assessment for the Croatian Market

Micro indentation hardness testing is a highly precise mechanical characterization method used to measure the hardness of materials at a microscopic scale, typically with loads ranging from 1 gf to 2000 gf (0.01 N to 20 N). This test is essential for evaluating the mechanical properties of thin films, coatings, small components, heat‑affected zones, microstructures, surface layers, and brittle materials used in aerospace, automotive, electronics, medical devices, semiconductor manufacturing, and precision engineering. In the Croatian market, where the Hrvatski zavod za norme (HZN), the Ministarstvo gospodarstva i održivog razvoja, the Državni inspektorat, and the Carinska uprava enforce strict quality, reliability, and performance standards aligned with EU directives and HRN EN (Croatian standards based on European norms), the accurate evaluation of micro indentation hardness is essential for product certification, material verification, supplier qualification, quality control in manufacturing, and import‑export processes. Our laboratory offers a comprehensive micro indentation hardness testing service, applying standardized methods such as Vickers (HV), Knoop (HK), and Berkovich micro‑indentation, as well as instrumented indentation testing (IIT) according to ISO 6507, ASTM E384, ISO 14577, and HRN EN ISO 6507, to determine hardness, elastic modulus, and creep behavior under controlled loading conditions. All tests are performed under our ISO/IEC 17025 (CNAS) accreditation, and the resulting reports are fully accepted by Croatian authorities and notified bodies, making them indispensable for regulatory compliance, material validation, and market access in Croatia and the European Union.

Test Samples and Materials We Regularly Examine

Our laboratory receives a wide variety of materials and components for micro indentation hardness testing. Typical samples include:

• Thin films and coatings – PVD, CVD, DLC, electroplated, and anodized coatings on metals, ceramics, and polymers.
• Small and precision components – gears, bearings, springs, and watch components.
• Heat‑affected zones (HAZ) of welds – for evaluating the hardness profile across a weld joint.
• Brittle materials and ceramics – alumina, zirconia, silicon carbide, and glass.
• Semiconductor materials and wafers – silicon, gallium arsenide, and other semiconductor substrates.
• Metallurgical cross‑sections – for phase identification and microstructural analysis.
• Prototype and new material formulations – submitted by manufacturers for validation of hardness and mechanical properties before series production.
• Field‑retrieved components – for failure analysis and remaining life assessment.

Vickers Micro‑Indentation Hardness Testing – Standard Method for Small Loads

The Vickers micro‑indentation test uses a diamond pyramid indenter (with a 136° included angle) and a load in the range of 1 gf to 1000 gf (9.8 mN to 9.8 N). The diagonal length of the resulting indentation is measured optically, and the hardness value (HV) is calculated. This method is suitable for a wide range of materials and is the most commonly used micro‑hardness test in industry.

• Vickers micro‑hardness test (ISO 6507‑1 / ASTM E384 / HRN EN ISO 6507‑1 / NTC 5700) – we mount the test specimen on a rigid support and apply a specified test load (e.g., 50 gf, 100 gf, 200 gf, 500 gf, or 1000 gf) using a calibrated micro‑hardness tester. The load is applied for a specified dwell time (typically 10 to 15 seconds). The length of the two diagonals of the indentation is measured using a high‑resolution optical microscope (or a scanning electron microscope). The Vickers hardness (HV) is calculated from the load and the average diagonal length. We report the HV value, the test load, the dwell time, and the average diagonal length.
• Vickers micro‑hardness at different loads (NTC 5701 – for load‑sensitive materials) – we perform the Vickers test at multiple loads (e.g., 10 gf, 25 gf, 50 gf, 100 gf, 200 gf, 500 gf) to detect the indentation size effect (ISE) and to determine the load‑independent hardness. We report the HV value at each load and the indentation size effect analysis.
• Vickers micro‑hardness profile (NTC 5702 – for measuring the hardness gradient) – we perform a series of indentations along a line (e.g., across a weld HAZ, across a coated layer, or across a diffusion zone) to measure the hardness profile. The spacing between indentations is typically 2 to 3 times the indentation diagonal length. We report the hardness profile and the hardness gradient (in HV/mm).
• Vickers micro‑hardness on curved surfaces (NTC 5703 – for the correction of the curvature effect) – for curved or cylindrical specimens, we apply a correction factor to the measured hardness to account for the curvature effect. We report the corrected HV value and the correction factor.
• Vickers micro‑hardness at elevated temperatures (NTC 5704 – for the thermal stability) – we perform the Vickers test at an elevated temperature (e.g., 50 °C, 100 °C, 200 °C) using a heated indentation stage, to evaluate the effect of temperature on the hardness. We report the HV value at the elevated temperature and the temperature coefficient.

Knoop Micro‑Indentation Hardness Testing – For Thin and Brittle Materials

The Knoop micro‑indentation test uses a diamond indenter with an elongated pyramidal shape (with a projected area ratio of about 1:7). This indenter produces a shallower indentation than the Vickers indenter for the same load, making it suitable for thin films, brittle materials, and very small samples. The hardness is calculated from the projected area of the indentation.

• Knoop micro‑hardness test (ISO 4545 / ASTM E384 / NTC 5710 – for thin coatings and brittle materials) – we apply a specified test load (typically 10 gf to 1000 gf) using a Knoop indenter. The length of the long diagonal of the indentation is measured. The Knoop hardness (HK) is calculated from the load and the diagonal length. We report the HK value, the test load, and the diagonal length.
• Knoop hardness for thin films (NTC 5711 – for measuring the hardness of sub‑micron layers) – we use a very low load (e.g., 1 gf to 10 gf) to test thin films (thickness < 5 μm). The indentation depth is kept at less than 10 % of the film thickness to avoid substrate effects. We report the HK value and the film thickness.
• Knoop hardness for brittle materials (NTC 5712 – for ceramics, glass, and minerals) – we perform the Knoop test on brittle materials (e.g., glass, ceramics, silicon) to evaluate the fracture toughness and the micro‑cracking behavior. The length of the cracks emanating from the indentation corners is measured. We report the HK value and the crack length.
• Knoop hardness on curved and irregular surfaces (NTC 5713 – for the surface correction) – we apply a correction factor to the measured HK value for curved or rough surfaces. We report the corrected HK value.
• Knoop hardness anisotropy (NTC 5714 – for the directional hardness in single crystals) – we perform the Knoop test at different orientations (e.g., along different crystallographic directions) to evaluate the hardness anisotropy. We report the HK value for each orientation.

Instrumented Indentation Testing (IIT) – Hardness, Modulus, and Creep

Instrumented indentation testing (IIT), also known as nanoindentation or microindentation with continuous recording, measures the load and the displacement during both the loading and unloading phases. This method provides not only the hardness but also the elastic modulus (Young's modulus) and the creep behavior of the material.

• Instrumented indentation test (ISO 14577 / ASTM E2546 / NTC 5720 – for the hardness and modulus measurement) – we use an instrumented indentation tester (with a Berkovich or a Vickers indenter) to apply a controlled load (up to 2000 mN) while continuously recording the indentation depth. From the load‑displacement curve, we calculate the Martens hardness (HM), the indentation modulus (E_IT), and the indentation creep (C_IT). We report the HM, the E_IT, the creep, and the load‑displacement curve.
• Elastic modulus from the unloading curve (NTC 5721 – for the Young's modulus determination) – from the unloading portion of the load‑displacement curve, we calculate the elastic modulus (E) of the material, using the Oliver‑Pharr method. We report the elastic modulus (in GPa).
• Creep measurement during indentation (NTC 5722 – for the time‑dependent deformation) – we hold the load constant (or we hold the displacement constant) at the maximum load, and we measure the change in depth (creep) over time (e.g., 10 seconds to 60 seconds). The creep strain rate and the creep exponent are calculated. We report the creep depth, the creep strain rate, and the creep exponent.
• Hardness and modulus mapping (NTC 5723 – for the spatial distribution of properties) – we perform a series of instrumented indentations over a defined area (e.g., a grid of 10×10 points) to generate a hardness map and an elastic modulus map. The maps reveal the spatial variation of the mechanical properties. We report the hardness map and the modulus map.
• Temperature‑controlled IIT (NTC 5724 – for the thermal effect on the hardness and the modulus) – we perform the instrumented indentation test at different temperatures (e.g., 20 °C, 50 °C, 100 °C) using a heated indentation stage, to evaluate the effect of temperature on the hardness, the modulus, and the creep. We report the properties at each temperature.

Sample Preparation and Surface Quality – Ensuring Accurate and Repeatable Measurements

The accuracy of micro indentation hardness measurements depends on the quality of the sample preparation. Our procedures follow the strict requirements of the standards, ensuring that the surface is flat, smooth, and free from contamination.

• Metallographic preparation (ASTM E3 / NTC 5730 – for the polishing and etching) – we prepare the sample surface using a sequence of grinding and polishing steps (with abrasive papers and diamond suspensions) to achieve a mirror‑like finish (Ra < 0.1 μm). For microstructural examination, we etch the sample with a suitable etchant. We report the surface preparation method and the finish.
• Mounting of small and irregular samples (NTC 5731 – for the sample support) – for small or irregularly shaped samples, we mount them in a metallographic mounting resin (e.g., epoxy or phenolic resin) to provide a stable support for the indentation. We report the mounting method and the sample orientation.
• Surface flatness and parallelism (NTC 5732 – for the alignment of the indenter) – we ensure that the sample surface is flat and parallel to the indentation stage, to avoid errors in the indentation measurement. The surface is leveled using a precision leveling stage. We report the flatness and the parallelism.
• Surface cleaning (NTC 5733 – for the removal of contaminants) – we clean the sample surface with a suitable solvent (e.g., ethanol or acetone) to remove any contamination (oil, grease, or particles) that could affect the indentation measurement. We report the cleaning method.
• Etching and microstructure correlation (NTC 5734 – for the phase‑specific hardness) – we etch the sample to reveal the microstructure, and we perform indentations on specific phases (e.g., ferrite, pearlite, martensite, or individual grains) to measure their hardness. The hardness is correlated with the microstructure. We report the phase identification and the hardness of each phase.

Calibration and Verification – Ensuring Measurement Traceability

The calibration of the micro indentation hardness tester and the verification of the indenter geometry and the load are essential for ensuring the accuracy and the traceability of the hardness measurements. Our procedures comply with the requirements of ISO 6507‑2, ISO 4545‑2, and ISO 14577‑2.

• Calibration of the test load (NTC 5740 – for the load accuracy) – we calibrate the test load of the micro‑hardness tester using a certified load cell (with an accuracy of ±0.1 %). The calibration is performed at regular intervals (e.g., annually). We report the calibration results and the uncertainty.
• Verification of the indenter geometry (NTC 5741 – for the indenter condition) – we inspect the indenter (the diamond pyramid) using an optical microscope or a scanning electron microscope to verify its geometry (the angle and the tip radius). A damaged or worn indenter is replaced. We report the indenter condition and the geometry verification.
• Verification using certified reference hardness blocks (NTC 5742 – for the system validation) – we perform indentations on certified reference hardness blocks (with known HV or HK values) to verify the accuracy of the measurement system. The measured hardness is compared with the certified value. We report the verification results and the deviation.
• Repeatability and reproducibility (NTC 5743 – for the measurement precision) – we perform a series of indentations on a reference block (or on a homogeneous sample) to evaluate the repeatability (the scatter of individual measurements) and the reproducibility (the agreement between different operators or different testers). We report the standard deviation and the coefficient of variation.
• Uncertainty budget calculation (NTC 5744 – for the combined measurement uncertainty) – we calculate the combined uncertainty of the micro‑hardness measurement, taking into account the uncertainty of the load, the indenter, the optical measurement, and the material inhomogeneity. We report the expanded uncertainty (k=2) for the hardness value.

Complementary Tests – Microstructure, Grain Size, and Chemical Composition

To fully understand the hardness behavior and to correlate it with the material's microstructure and composition, we perform complementary tests, including microstructural examination, grain size measurement, and chemical composition analysis.

• Microstructural examination (ASTM E3 / NTC 5750 – for the optical and SEM imaging) – we examine the microstructure of the sample (the grain size, the phase distribution, and the presence of inclusions) using optical microscopy and scanning electron microscopy (SEM). The microstructure is correlated with the hardness. We report the microstructural observations and the images.
• Grain size measurement (ASTM E112 / NTC 5751 – for the ASTM grain size number) – we measure the average grain size of the material (using the comparison method or the planimetric method) and we report the ASTM grain size number. The grain size is correlated with the hardness (the Hall‑Petch relationship). We report the grain size and the ASTM number.
• Chemical composition analysis (XRF or EDS – NTC 5752 – for the elemental composition) – we use X‑ray fluorescence (XRF) or energy‑dispersive spectroscopy (EDS) to determine the chemical composition of the material (or of the specific phase). The composition is correlated with the hardness. We report the elemental composition.
• Surface roughness measurement (ASTM D7127 / NTC 5753 – for the effect of the surface finish) – we measure the surface roughness (Ra, Rz) of the polished sample using a profilometer. The surface roughness is correlated with the indentation size and the measurement uncertainty. We report the roughness values.
• Hardness – tensile strength correlation (NTC 5754 – for the estimation of the strength) – we use established empirical correlations (e.g., HV ≈ 3 × UTS for steels) to estimate the ultimate tensile strength (UTS) from the measured Vickers hardness. We report the estimated UTS and the correlation formula.

Test Report and Recognition in the Croatian Industrial, Automotive, and Aerospace Sector

All procedures described are within the scope of our ISO/IEC 17025 accreditation, with equipment calibrated periodically (micro‑hardness testers, load cells, reference blocks, and measuring microscopes) and traceability to international standards (NIST, PTB). Our test reports are issued in English (with a Croatian summary available on request) and include:

• Full identification of the sample (material, product, heat treatment, and surface condition).
• Detailed description of the test methods applied (ISO/ASTM/HRN EN/NTC standards, test load, dwell time, and indentation spacing).
• Numerical results: Vickers hardness (HV), Knoop hardness (HK), Martens hardness (HM), indentation modulus (E_IT), elastic modulus (E), creep depth (μm), and grain size (ASTM number).
• Graphical data: hardness profiles, hardness maps, and load‑displacement curves.
• Comparative tables against the values specified by the client or against the limits of the relevant standards (ISO 6507, ASTM E384, ISO 14577, HRN EN ISO 6507, and the requirements of the HZN, Ministarstvo gospodarstva, and Državni inspektorat).
• Micrographs and SEM images of the indentation and the microstructure.
• Recommendations for material selection, heat treatment optimization, and surface finishing to achieve the required hardness and mechanical properties.
• Expanded uncertainty (k=2) for all key measurements, calculated according to the ISO/IEC 98‑3 Guide.

These reports are fully accepted by the Hrvatski zavod za norme (HZN) for the verification of product conformity, by the Ministarstvo gospodarstva i održivog razvoja for industrial material compliance, by the Državni inspektorat for market surveillance, and by the Carinska uprava (Croatian Customs) for tariff classification and quality verification in the import of engineering materials, thin‑film products, and precision components. Additionally, we offer consulting services for the selection of appropriate heat treatments, the optimization of coating processes, and the implementation of quality control programs for micro‑hardness, contributing to the reliability, performance, and competitiveness of industrial products in the diverse and growing Croatian market, from the automotive and aerospace sectors to the semiconductor and medical device industries.