Easy and cost effective measurements
Information of the thermo physical properties of materials and heat transfer optimization of final products is becoming more and more vital for industrial applications. Over the past few decades, the flash method has developed into the most commonly used technique for the measurement of the thermal diffusivity and thermal conductivity of various kinds of solids, powders and liquids.
Principle of the LFA 500:
The sample is either positioned on a sample robot, which is surrounded by a furnace (LFA 500-LT/500/1000) or within one out of five microheaters located on a moveable linear stage (LFA 500/1250). For the measurement, the furnace is held at a predetermined temperature and a programmable energy pulse irradiates the back side of the sample, resulting in a homogeneous temperature rise at the sample surface.
The resulting temperature rise of the surface of the sample is measured by a very sensitive high speed IR detector . Both, thermal diffusiviy and specific heat can be determined from the temperature vs. time data. If the density (r) is identified, the thermal conductivity can be calculated:
In a nutshell
High temperature configuration
The Light Flash Series LFA 500 is available with different furnace options (-100 up to 500°C, RT up to 500/1000°C or 1250°C, 1450°C with boost), ensuring the right temperature range for your application.
Each Linseis LFA 500 model is equipped with a sample robot for maximum sample throughput. LFA 500 – 500/1000 with up to 18 samples, LFA 500/1250 with up to 5 samples.
COMBINED “DOUZA” MODEL
Worlds only combined solution for combined heat loss and finite pulse corrections for the flash method.
One fits all model. No more uncertainty of selecting the appropriate model.
DOUZA – Combined model for Translucent Samples
Accounts for the distinctive problems relating to translucent samples and ensures perfect measurement results.
High Speed IR or Micro-heater furnace
Fast measurements cycling due to very fast heating and cooling rates.
Perfect temperature control with low mass furnace, no measurement error due to temperature fluctuation at sample.
Linseis LFA 500/1250°C (1450°C with boost)
|Model||LFA 500 (LT/500/1000/1250)*|
|Temperature range:||RT up to 1250°c|
|Heating rate:||0.01 up to 300°C/min|
|Pulse source:||Light Flash Lamp, user exchangeable|
|Pulse energy:||up to 15J/Pulse (variable pulse energy: software controlled)|
|Measuring range alpha:||0.01 up to 2000 mm²/s|
|Measuring range lambda:||0.1 to 4000 W/(m∙K)|
|Repeatability cp:||±3% (for most materials)|
|Repeatability alpha:||±1.9% (for most materials)|
|Accuracy cp:||±5% (for most materials)|
|Accuracy alpha:||±2.4% (for most materials)|
|Pulse length:||Software adjustable|
|– (Unsichtbar, siehe EXTRA CLASS NAME unten) –||– (Unsichtbar, siehe EXTRA CLASS NAME unten) –|
|Samples:||Solids, Liquids, Powders, Pastes, Thin films and more|
|Sample dimensions:||∅ 3, 6, 8, 10, 12.7 or 25.4 mm
square samples 6×6, 10×10 or 20×20 mm
|Sensor type:||InSb, LN2 cooled|
|Sample Thickness:||from thin films up to 6 mm in height|
|Nr. of samples:||Sample robot for up to 18 samples
up to 5 samples (LFA 500/1250)
|Sample holder:||Graphite, SiC, Al2O3, Metal (others on request)
|Atmospheres:||inert, oxidizing, reducing, vacuum|
|Data acquisition:||2 MHz|
*Specs depend on configurations
Various sample carriers for ideal measurements
Sample carrier for LFA 500 – LT/500/1000:
- 18 round or square for samples 3 mm or 6 mm
- 6 samples round or square for 3 mm, 6 mm, 10 mm or 12.7 mm
- 3 samples round for 25.4 mm or square 20 mm
Sample carrier for LFA 500/1250:
- 5 samples, ø up to 12.7 mm, up to 10×10 mm
- others on request
- Sample holder square samples, 3×3 mm / 10×10 mm / 20×20 mm
- Sample holder round samples 3 mm / 6 mm / 10 mm / 12.7 mm / 25.4 mm
- Liquid Container, Sample holder for lamellas, In plane / Cross plane, Sample holder round, Sample holder for liquids and pastes, Torque pressure container
All thermo analytical devices of LINSEIS are PC controlled, the individual software modules exclusively run under Microsoft® Windows® operating systems. The complete software consists of 3 modules: temperature control, data acquisition and data evaluation. The Linseis 32 – bit software encounters all essential features for measurement preparation, execution and evaluation, just like with other thermo analytical experiments.
- Precise pulse length correction, pulse mapping
- Heat-loss corrections
- Analysis of 2- or 3-layers systems
- Wizard for selection of the perfect evaluation model
- Specific heat determination
- Contact resistance determination in multi-layer systems
- Multi-method analysis: DIL, STA, LSR and LZT
- Automatic or manual input of related measurement data (density, specific heat)
- Model wizard for selection of the appropriate model
- Finite pulse correction
- Heat loss correction
- Multilayer model
- Determination of contact resistance
- Cp (Specific Heat) determination by comparative method
- Easy and user-friendly data input for temperature segments, gases etc.
- Controllable sample robot
- Software automatically displays corrected measurements after the energy pulse
- Fully automated measurement procedure for multi sample measurements
PTFE is a versatile material and used in many different industries/applications such as chemical processing and petrochemical sectors: used for vessel linings, seals, spacers, gaskets, well-drilling parts and washers, since PTFE is chemically inert and resistant to corrosion. Laboratory applications: Tubing, piping, containers and vessels due to resistance to chemicals and the absence of contaminants attaching to the surface of PTFE products. Electrical industry: used as an insulator in the form of spacers, tubing and the like Virgin PTFE had been approved by the FDA for use in the pharmaceutical, beverage, food and cosmetics industries in the form of conveyor components, slides, guide rails, along with other parts used in ovens and other heated systems. Semiconductor sector: used as an insulator in the production of discrete components such as capacitors and in the chip manufacturing process.
BCR 724, a standard glass ceramic has been measured using LFA 500. Therefore, a small disc of 1 mm thickness and 25 mm diameter was cut out of a plate of bulk material and coated with graphite for the measurement.
The LFA 500 gives the thermal diffusivity as a direct function of temperature. The Cp data was obtained in a comparative way by measuring a known ceramic standard under the same conditions in a second sample position of the same sample holder. Using this, the thermal conductivity was calculated out of the product of density, specific heat and thermal diffusivity. The result shows a slightly decreasing thermal diffusivity and conductivity while the Cp value increases over temperature.
A graphite sample has been investigated using the LFA 500. Thermal diffusivity has been determined directly at several temperature between RT and 1100°C. Specific heat capacity has been determined using a known graphite standard in a second sample position as a reference in the same measurement. The product out of diffusivity, specific heat and density gives the corresponding thermal conductivity. The result shows a linear decreasing thermal conductivity which is typical and a thermal diffusivity that is showing a plateau above 500°C. The Cp is slightly increasing over temperature.
Pyroceram, a glass ceramic trademark of Corning used as a standard material in various applications, has been measured using the LFA 500 to show the reproducibility of thermal diffusivity values. In total 18 measurements were performed with 18 samples that were cut out of one bulk block. Each sample was measured separately and the result shows a spread in the result that is in a range of +/- 1 % in a temperature range up to 600°C.