Providing confidence in components at all temperatures
We enable organisations to understand with confidence the thermal performance of their materials and improve their process modelling. Understanding the thermal properties and performance of all materials and structures subject to harsh environments is essential to having confidence in their design, lifetime and function, across a wide range of industries. NPL has a unique range of instruments to support Industry to understand the thermophysical properties of their materials to support this understanding and provide reliable data to their process models
We provide thermal performance measurements to help ensure the reliability of consumer products and electronics, meet regulatory requirements and improve productivity of advanced manufacturing processes through better optimisation of the manufacturing process and design of components. . Our expertise can also help to create durable and lightweight structures for aerospace or automotive industries; conserve energy and reduce waste in nuclear power generation and other energy industries and improve quality of life through support to the healthcare sector.
Thermal conductivity, heat flow and thermal diffusivity
We are one of the world-leading National Measurement Institutes in thermal conductivity measurements, and have developed a range of UK national standard facilities for direct thermal conductivity measurements covering temperatures from -170 °C to 800 °C and thermal conductivities from 0.01 W/(m*K) to 240 W/(m*K). We have also developed a range of thermal conductivity reference materials and transfer standards conforming to the ISO 17034, to provide traceability for industry worldwide. All our thermal conductivity measurement services using direct methods are UKAS accredited. Direct measurement of thermal conductivity uses steady state methods and is limited to 500 °C for high conductivity materials and to 800 °C for insulation, but we can derive the thermal conductivity at higher temperatures (to over 1500 °C) using values of thermal diffusivity, specific heat capacity and density. This provides a relatively fast and cost-effective way of obtaining data over a wider temperature range.
Our thermal diffusivity measurements have been validated against European Certified Reference Material and NMIJ Certified Reference Material. In addition, the Laser Flash (LFA) thermal diffusivity measurements at NPL have been compared with measurements in other National Measurement Institutes (NMIs) in an International Bureau of Weights and Measures (BIPM) Consultative Committee on Thermometry (CCT) Supplementary Comparison, CCT-S3.
Thermal expansion is measured by contact dilatometry and our instruments can cover the range 150 °C to 1450 °C, including measurement of some liquids in a specially designed cell. Phase changes, annealing and hysteresis can be assessed.
Density is measured by the Archimedes method at room temperature and a value for open, or surface porosity can also be determined. By using this and thermal expansion data the density can be calculated over a wide temperature range.
Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetry (TGA) techniques can provide data for specific heat capacity, mechanical properties and mass change information, over low and high temperature ranges. We can advise on the best methods available for an application. Our current research is improving the reliability and temperature ranges of these measurements when using different methods.
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