Accurate Measurement of Transformation Energetics and Specific Heat by DSC in the High-temperature Region

A new differential scanning calorimeter NETZSCH model DSC 404 C Pegasus was developed for the measurement of specific heat and transformation energetics. The system allows tests between -120 and 1650°C with high accuracy. Presented in this work are the design of the DSC and measurements on various kinds of materials such as ceramics and metals, demonstrating the capability of the new system at low temperatures as well as in the high-temperature region. This revised version was published online in July 2006 with corrections to the Cover Date.     

Novel instrument for high temperature thermogravimetric measurements in high water vapour contents

Summary A novel instrument for high temperature thermogravimetric measurements in atmospheres containing high water vapour contents was developed in a collaboration between Netzsch and Risø National Laboratory. The development of the instrument was initiated to facilitate the investigation of high temperature corrosion of steels in humidified atmospheres. The instrument consists of a standard thermal analyser unit, including a new water vapour furnace, balance and sample carrier. The design of the instrument is discussed and thermogravimetric measurements on a Fe₇₈Cr₂₂ steel are presented.     

A novel direct coupling of simultaneous thermal analysis (STA) and Fourier transform-infrared (FT-IR) spectroscopy

Evolved gas analysis (EGA) from thermal analyzers such as thermogravimetry (TG) or simultaneous thermal analysis (STA) which refers to simultaneous TG–DSC is well established since it greatly enhances the value of TG or TG–DSC results. The sensitive and selective FT-IR technique is in particular useful for the analysis of organic molecules but also for infrared active permanent gases evolved during most decomposition processes. The coupling interface between thermal analyzers and FT-IR spectrometers usually consists of heated adapters and a flexible, heated transfer line. In this work, a novel direct coupling of an STA instrument and an FT-IR spectrometer without a transfer line is presented. A very small FT-IR spectrometer is directly mounted on top of the STA furnace leading to a compact and fully integrated STA–FT-IR coupling system. The possibilities and the value of simultaneous STA–FT-IR measurements are demonstrated for organic, biomass, and ceramic samples in the temperature range between room temperature and about 1,500 °C. Various samples from the field of inorganics and organics—especially polymers—were furthermore measured showing the advantages of the direct STA–FT-IR coupling compared to state-of-the-art STA–FT-IR coupling using a heated transfer line: we found that the time delay caused by the volume of the transfer line itself is rather negligible whereas a significantly better correlation between gas detection and TG results was observed in case of some highly condensable decomposition gases. Aspects of quantification of evolved gases are furthermore discussed as well as the known nonlinearity of FT-IR detection at higher gas concentrations.     

Thermophysical property determination of high temperature alloys by thermal analysis

Differential scanning calorimetric measurements to determine solidus and liquidus temperatures and latent heat of fusion of two high temperature materials, PWA1484 and an experimental gamma titanium aluminide alloy, are presented. The solidus and liquidus temperatures of PWA1484 are 1340 and 1404°C. The solidus and liquidus temperatures of the titanium aluminide alloy are 1453 and 1522°C. Solidus and liquidus temperatures determined from actual heating and cooling curves, which were measured using imbedded thermocouples and analyzed by a pseudo-differential thermal analysis technique are found to be in good agreement with the differential scanning calorimetric measurements. This revised version was published online in July 2006 with corrections to the Cover Date.