Heat flow for thermal conductivity testing measuring instrument LFA 707 StratoFlash® Classic

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Product overview

• Laser-flash analyzer for precise determination of thermal diffusivity and, combined with density/specific heat data, thermal conductivity and specific heat capacity.
• Designed for applications in metals, glass and ceramics industries as well as R&D and quality control.

Main features

• Wide temperature range: room temperature to 1600 °C for high-temperature measurements.
• Fully automatic sample changer (ASC) available in 3- or 5-sample variants to increase throughput and measurement comparability.
• Precise pulsed laser system (Nd:Glass) at 1054 nm, software-controlled pulse width and adjustable pulse energy for adaptation to various sample types.
• Support for many sample holders and geometries: round and square specimens, specialized holders for liquids, pastes, powders, fibers, resins, laminates and in-plane analyses.
• Measurements under inert gas or high vacuum (turbo pump enables < 2 x 10^-5 mbar).
• Integrated modern software environment (Proteus / NETZSCH Assistant): separate measurement and analysis software, SQL-based data management, advanced models and correction procedures, export and visualization tools.

Method / Measurement principle
The laser-flash method is a fast, absolute, non-destructive and contactless technique to determine thermal diffusivity. A short energy pulse on the front face of a plane-parallel sample produces a temperature rise on the rear face measured by an IR detector. Thermal properties are calculated from the time-dependent temperature response.

Key formula
λ(T) = α(T) ⋅ c_p(T) ⋅ ρ(T) (λ = thermal conductivity; α = thermal diffusivity; c_p = specific heat capacity; ρ = density)

Laser system (selected specifications)

• Pulsed Nd:Glass laser, wavelength 1054 nm.
• Software-controlled pulse width and energy; typical pulse widths from <0.05 ms to 1.5 ms (stepless/stepwise adjustable).
• Adjustable pulse energy: approx. 0.25 J to 25 J per pulse.
• Patented pulse mapping / finite pulse correction (patent reference available).

Samples and sample holders

• Round samples: diameters 6 mm, 8 mm, 10 mm, 12.7 mm, 20 mm, 25.4 mm; thickness range typically 0.1 mm to 6 mm.
• Square samples: e.g. 10 × 10 mm, 20 × 20 mm; thickness 0.1 mm to 6 mm.
• Special holders for polymer melts/low-viscosity liquids (including water), resins during curing, pastes, powders, fibers, laminates, in-plane analyses and samples under mechanical load.
• Non-destructive testing: samples can often be reused for further analyses.

Detector and atmosphere

• Standard detector: InSb (suitable RT to 1600 °C), optional LN2 auto-fill system with 35 L dewar.
• Measurement atmospheres: inert gas or high vacuum (typ. < 2 x 10^-5 mbar with turbomolecular pump) to minimize heat loss and oxidation.

Software / Data processing

• 64-bit architecture with SQL database; measurement and analysis software separated to allow analysis independent of the instrument.
• NETZSCH Assistant for overview and management of connected instruments and software components.
• Integrated calculation models including enhanced Cape–Lehman variant and dedicated models for multilayer, anisotropic or partially transparent samples.
• Baseline correction, pulse correction, goodness-of-fit evaluation, smoothing, multi-shot averaging and extensive export options (e.g. CSV).

Applications

• Materials research and development (metals, ceramics, glass, polymers, composites).
• Quality control in industrial processes.
• High-temperature measurements (e.g. refractory materials, high-temperature alloys).
• Analysis of thin films, multilayer laminates and anisotropic materials (in-plane analyses possible).

Key advantages

• High measurement precision combined with fast throughput via automatic sample changer.
• Flexible adaptation to diverse sample types and test tasks through a modular holder system.
• Advanced algorithms and corrections for accurate results under challenging measurement conditions.

Technical characteristics / specifications

• Temperature range: room temperature to 1600 °C.
• Heating rates: approx. 0.01 K/min to 50 K/min (depending on program).
• Automatic sample changer: versions for 3 positions (samples ≤ 25.4 mm) and 5 positions (samples ≤ 12.7 mm).
• Thermal diffusivity measurement range: approx. 0.01 mm²/s to 2000 mm²/s.
• Thermal conductivity range: approx. 0.1 W/(m·K) to 4000 W/(m·K).
• Laser system: pulsed Nd:Glass, 1054 nm; pulse-width control (<0.05 ms to 1.5 ms in steps of 0.01 ms typical); pulse energy ~0.25–25 J/pulse; patented pulse correction.
• Accuracy*: thermal diffusivity ±2.5 %; specific heat capacity ±5 % (validation against reference materials).
• Repeatability**: thermal diffusivity ±1 %; specific heat capacity ±3 % (same operator/instrument).
• Measurement atmosphere: inert gas or vacuum (turbomolecular pump, typ. <2 x 10⁻⁵ mbar).
• Detector: InSb (suitable RT to 1600 °C), optional LN2 auto-fill system (35 L dewar).
• Software: modern 64-bit software with SQL database, separate measurement and analysis software, advanced models and corrections, NETZSCH Assistant.
• Sample geometries: round (6 mm … 25.4 mm), square (e.g. 10×10 mm, 20×20 mm), thickness 0.1 mm … 6 mm (additional holders on request).
• Special holders: for polymer melts/low-viscosity liquids, resins during curing, pastes, powders, fibers, laminates, in-plane analyses and samples under mechanical pressure.
• Note: * Deviation versus literature values (validation with reference materials). ** Repeatability deviation with same operator and instrument.