Analyzing & Testing Thermal Diffusivity – Thermal Conductivity Method, Technique, Applications LFA 447 Leading Thermal Analysis LFA 447 NanoFlash® What is the heating/cooling load of a diffusivity and thermal conductivity only some advantages of this non- building as a function of the weather must be known. Engineers must select contact test method. NETZSCH offers a conditions and how can I improve it? from a variety of test methods to variety of flash systems to cover a broad How can I improve the heat transfer characterize the diverse array of range of applications and out of an electronic component? materials and configurations they temperatures from -125°C up to What are the optimum materials and employ in their designs. For ceramics, 2800°C. The NETZSCH NanoFlash® how do I design a heat exchanger metals, composites, and multi-layer system is designed as a cost-effective, system to achieve a required efficiency? systems, the flash technique is an ideal easy-to-operate, highly accurate In order to answer questions like these, choice. Easy sample preparation, fast instrument for testing between room material properties such as thermal testing times, and high accuracy are temperature and 300°C. s s e Clay , Silicon Carbide ous Insulations ds, Oils ds, Fiber Insulations, opor ene, PU Foam ete, Glass, Fir , Copper ous Ceramics, Refractorie , Micr ood, Polymers, Coal ater acuum Insulation on, Steel, Silicon V Air Polystyr Fiber Boar Building Boar W W Concr Por AlumonosilicatesSilicon Nitride Alumina, Carbon Bricks Ir Aluminum, GraphiteSilver Diamond Heat Flow Meter (-20°C to 100°C) Guarded Hot Plate (-160°C to 250°C) Hot Wire (RT to 1500°C) Laser Flash (-125°C to 2800°C) 0.001 0.010 0.100 1.00 10 100 1000 Thermal Conductivity at RT (W/(m.K)) For the measurement of low conductivity Differential scanning calorimeters materials such as insulations, NETZSCH (DSC 404 F1/F3 Pegasus®) for the offers a broad selection of Heat Flow measurement of specific heat, and Meters and Guarded Hot Plate dilatometers (DIL 402 C series) for the Instruments. For the analysis of analysis of density and length changes refractory materials, a hot wire system up to high temperatures, are also (TCT 426) is available. available. 2 Flash Apparatus LFA 447 NanoFlash® Advanced Data Analysis Standardized Test Method The NETZSCH LFA 447 NanoFlash® is The evaluation of the measured data The NanoFlash® works according to based on the well-known flash method. can be done using the well known half- national and international standards In this method, the front side of a time method: such as ASTM E1461, DIN EN 821, plane-parallel sample is heated by a 2 DIN 30905 and ISO 22007-4:2008. a = 0.1388 · –d– short light pulse. The resulting t temperature rise on the rear surface is ½ measured using an infrared detector. d = sample thickness MTX-Version By analysis of the resulting temperature- versus-time curve, the thermal diffusivity The NanoFlash® system additionally A special version with a matrix system can be determined. allows the consideration of radial and (MTX) allows scanning of surfaces facial heat losses and finite pulse effects (50 mm x 50 mm) for analysis of the The LFA 447 NanoFlash® is a powerful using advanced mathematical thermal diffusivity over the area. This research tool for making accurate, rapid regression routines. enables the detection of structural thermal diffusivity tests on small specimens. Using the multiproperty measurement inhomogeneities or defects under the It can complete tests on dozens of samples capabilities of the NanoFlash®, both surface. at room temperature in a single morning thermal diffusivity and specific heat can or make measurements at temperatures be determined simultaneously – on the up to 300°C automatically. same specimen – thus yielding thermal conductivity if the density is known: Fast Test Times λ(T) = a(T) · cp(T) · ρ(T) The speed and repeatability of thermal diffusivity measurements have made this technique the method of choice among researchers worldwide, replacing traditional steady-state methods that are difficult, costly, and much slower. By measuring thermal diffusivity (a) of a material, its thermal conductivity (λ) can be determined if specific heat (cp) and density (ρ) are known. 3 System Setup – Software Detector Electronics IR Detector Sample Changer Heater System Electronics Optical Filter Reflector Flash Lamp Lamp Power Supply In the LFA 447 NanoFlash®, a state-of- Sample Placement The Furnace the-art technology is integrated in a compact measuring system. The flash The samples are placed in an automatic The system is equipped with a furnace lamps, sample, and detector are vertically sample changer which can test up to for temperature-dependent arranged. Therefore the use of mirrors four samples in one test. The samples measurements up to 300°C. The is not necessary. Short signal pathways are thereby brought into a special furnace is directly integrated into the and a good signal-to-noise ratio are sample carrier which can be adjusted sample changer of the system, thereby warranted. according to the user’s wishes. There whereby a small thermal mass and are standard carriers for testing of thereby fast heating and cooling times round samples with e.g., 10 mm, are secured. The Flash Lamp 12.7 mm or 25.4 mm diameter. Sample receptacles for the testing of square A high-performance Xenon flash lamp samples (e.g. 8 mm x 8 mm or The Detector is applied to produce the heat pulse on 12.7 mm x 12.7 mm) also exist (special the front of the sample. The lamp is sample holder sizes on request). The measurement of the temperature placed in a parabolic mirror, whereby a The measurement of the sample increase on the rear of the sample large part of the radiation given off is temperature is done with a temperature is carried out with a liquid-nitrogen- focused on the sample. The assembly of sensor which is integrated into the cooled InSb (Indium-Antimonide) the mirror and the position of the lamp system’s sample holder plate. Special infrared detector. The non-contact are conceived such that a homogenous sample holders are available for the measurement of the temperature illumination of the entire sample surface measurement of liquids and pastes with increase guarantees an easy sample is warranted. The energy released from unmatched accuracy and test speed. change and a short response time for the flash lamp can be adjusted using the signal acquisition system. Both the the software (voltage and pulse length). detector and amplifier components are The pulse width is adjustable between designed for measurements with data 0.06 ms and 0.3 ms. acquisition rates of 500 kHz. 4 Software The LFA 447 NanoFlash® run under Evaluation Tasks Evaluation Models Proteus® software on a Windows® operating system. It combines easy n Presentation of an individual More than 20 different models handling and complex evaluation response curve, the entire result as representing state-of-the-art technolo- routines, thus offering a solution to well as test parameters and gy are available to the user. These have almost every application challenge. measured values in one presentation been developed in cooperation with lea- n Free input or import of density and ding experts from science and industry: specific heat values for determination Software Features of thermal conductivity Accurate (patented) finite pulse n Simultaneous presentation of thermal correction n Multitasking: simultaneous diffusivity and conductivity data in Standard adiabatic analysis measurement and evaluation one plot Standard heat loss corrections in n Full network compatibility n Storage and restoration at any point accordance with Cowan, Clark and n Easy printout and export of of the analysis Taylor measuring curves and data (ASCII) n Presentation and new evaluation of Cowan-Fit: non-linear regression n Selectable screen design by data from previous measurements based on Cowan’s publication (incl. means of docking windows finite pulse correction) n Multi-moduling: operation of Improved Cape-Lehmann model: several different instruments with non-linear regression taking one computer radial and facial heat losses into n Integrated data base consideration Correction of radiation effects: radiation effects are taken into Measuring Tasks account for accurate analysis of tests on oxides, ceramics or glass n Full control of the sample changer (simultaneously with heat loss and n Easy and user-friendly input of test finite pulse corrections) parameters 2- or 3-layer systems: analysis of n Free selection of temperature multi-layer systems applying non- programs (heating, coding) linear regression, taking the heat n Automatic optimization of the loss into consideration (with optional system parameters (measuring time, finite pulse correction) amplification, etc.) Determination of the contact n Automatic evaluation of the resistance in a layered structure measurement after each shot with Model wizard: evaluation of a selected evaluation model response curve with several models simultaneously; determination of the optimum model using statistical criteria Determination of specific heat by means of a comparative method Calculation of thermal conductivity 5 LFA 447 NanoFlash® for a Wide Variety of Applications Performance – Stainless Steel and Pyroceram 9606 The thermal diffusivities of two well- known standard materials (NIST SRM 1461 Stainless Steel and Pyroceram 9606) were measured versus temperature with the LFA 447 NanoFlash®: The figure shows the measurement results as compared to literature values (Touloukian et al., 1970, Henderson et al., 1998) up to 200°C. It can clearly be seen that the deviations between the literature values and the measurement results are less than 3% (error bars). This demonstrates the high accuracy of this flash unit in the field of metals and ceramics. Accuracy – NIST SRM 8421 Electrolytic Iron A certified NIST thermal conductivity reference material (SRM 8421) was measured between room temperature and 100°C.