The NETZSCH LFA 457 MicroFlash -125 … 1100°C A. Lindemann, J. Blumm, NETZSCH-Gerätebau GmbH Wittelsbacherstr. 42 95100 Selb/Germany G. Jacquier NETZSCH-Gerätebau GmbH L’Orée d’Ecully – Allée A Chemin de la Forestière 69130 Ecully/France

NETZSCH LFA 457 MicroFlash - Measurement Principle - Introduced by Parker et al. 1961 The front surface of a plane-parallel sample is heated by a short light or laser pulse. The temperature rise on the rear surface is measured versus time using an IR detector.

NETZSCH LFA 457 MicroFlash - Instrument Design - Newest development Table-top unit Temperature range: -125 to 1100 °C (with two furnaces) Integrated sample changer

NETZSCH LFA 457 MicroFlash - Instrument Design - heating element radiation shield mirror sample t.c. sample carrier aperture detector dewar furnace hoist laser Vertical system Robot system for up to three samples (up to 12.7 mm in diameter) Special sample carrier for large samples (up to 25.4 mm in diameter) Vacuumtight (1 Pa)

NETZSCH LFA 457 MicroFlash - Sample Changer -

NETZSCH LFA 457 MicroFlash - Measurement Possibilities - Thermal Diffusivity a (absolute) Specific Heat cp (ratio method) Thermal Conductivity  calculation according to:

NETZSCH LFA 457 MicroFlash - Possible Sample Geometries -

NETZSCH LFA 457 MicroFlash - Ideal Sample Thicknesses -

NETZSCH LFA 457 MicroFlash - Analysis Routines (simple) -

Standard Application – Cu and Al

The New NETZSCH LFA Proteus Software – Specific Heat Measurement    For decades the acccuracy of specific heat measurements using the laser flash technique and therefore a direct determination of the thermal conductivity is an ongoing discussion. Nowadays, a comparative technique is generally employed, Comparing the detector signal height of a calibration standard with known specific heat with that one of the unknown sample:  

The New NETZSCH LFA Proteus Software – Specific Heat Measurement Current points of improvement: The heat loss corrected detector signal heights are employed for the calculations. The differences in the laser power between the sample and calibration run are considered in the analysis (LFA 457/LFA 427).  

The New NETZSCH LFA Proteus Software – Specific Heat Measurement +- 5 %

Standard Application – POCO AXM 5Q 5 % - Sample changer 1 heating 2 different samples

Standard Application – Stainless Steel 0.40 0.45 0.50 0.55 0.60 0.65 Specific Heat / (J/(g*K) 100 200 300 400 500 600 700 800 Temperature / °C 2 3 4 5 6 Thermal Diffusivity / mm²/s Thermal Diffusivity Specific Heat DSC 404 Test SRM 1461 - Stainless Steel

Standard Application – Stainless Steel

The New NETZSCH LFA Proteus Software – Specific Heat Measurement Critical points: The emissivities of sample and reference surfaces must be the same (generally a coating is required). The surface structure of sample and standard must be the same. The dimensions of standard and sample should be close to each other. The thermophysical properties of sample and standard should be close to each other.  

Application – Carbon-Containing Refractories The thermal diffusivity/thermal conductivity of refractory materials is generally measured using the hot-wire method. Due to contact reactions between hot wire and sample, this method is critical for Carbon- or SiC-containing refractories. The non-contact laser flash method allows more reliable fast measurements on such samples without major cost for consumables.                                                                                                  

Application – Carbon-Containing Refractories Large Sample

Application – Sintering of a Powder Metal In the production of powder metals the thermophysical properties prior to, during and after the sintering process are important parameters for optimization of the production process as well as quality control for final products.

Application – Sintering of a Powder Metal Sintering step

Application – Filled Rubber                                                   Wide Aquachannels® to reduce hydroplaning                                                                                                              Increased Tread Depth for more landings Kevlar® belts for added tread stability Wingstay® formulation to reduce cracking Goodyear Aircraft tire Photo: Bridgestone press release June 11th, 2004

Application – Filled Rubber

Application – Filled Rubber

NETZSCH LFA 457 MicroFlash - Specifications -   Desktop design Temperature ranges Furnace 1: 25 to 1100 °C Furnace 2: -125 to 500 °C (LN2 cooling) Exchangeable by user (motorized lift) Step-iso temperature programs Samples Handling: automatic sample changer Sample sizes: 12.7 mm diameter (ASC) 25.4 mm diam. max (single sample mode) Sample carriers: easily user interchangeable

NETZSCH LFA 457 MicroFlash - Specifications (cont.) -   Atmospheres Vacuum 10-2 mbar (1 Pa) Gas flow predefined, switching via software Laser up to 15 Joule / pulse Pulse energy variable (software controlled) Pulse width 330 µs Detectors Exchangeable MCT LN2 cooled, refilling intervall 8 or 24 h Exchangeable InSb LN2 cooled, refilling intervall 8 or 24 h

  Thermophysical Properties of a Carbon Composite AIRBUS Round Robin Test

EXPERIMENTAL PARAMETERS   Sample holder: 12.7 mm (round) Furnace: -125..500°C Detector: MCT (Mercury Cadmium Telluride) Measurement:5 shots at each temperature Reference for Cp: Pyroceram Correction: Cowan + Pulse x y z

Thermophysical properties of the Composite (z-direction)

Thermophysical properties of the Composite (y-direction)

Thermophysical properties of the Composite (x-direction)

Sample Direction Temp /°C Thermal Diffusivity /mm²/s Specific Heat /J/(g K) Thermal Conductivity /W/(m K) Z -50 0.538 0.526 0.443 25 0.465 0.990 0.720 90 0.416 1.205 0.785 Y 0.762 0.628 0.640 0.992 0.571 1.077 X 4.160 3.426 3.872 6.002 3.636 6.861

CONCLUSIONS T  a , Cp  l Highest conductivity  fiber direction Standard deviation  less than 2%

Thank you!