To improve the efficiency of gas turbines, the turbine inlet temperature needs to be increased. The highest temperature in the gas turbine cycle takes place at the exit of the combustion chamber and it is limited by the maximum temperature turbine blades, vanes and discs can withstand. A combination of advanced cooling designs and Thermal Barrier Coatings (TBCs) are used to achieve material surface temperatures of up to 1200°C. However, further temperature increases and materials that can withstand the harsh temperatures are required for next-generation engines. Research is underway to develop next-generation CMCs with 1480 °C temperature capability, but accurate data regarding the thermal load on the components must be well understood to ensure the component life and performance. However, temperature data is very difficult to accurately and reliably measure because the turbine rotates at high speed, the temperature rises very quickly with engine startup and the blades operate under harsh environments. At the operating temperature range of CMCs, typically platinum thermocouples are used, however, this material is incompatible with silicon carbide CMCs. Other temperature techniques such as infrared cameras and pyrometry need optical access and the results are affected by changes in emissivity that can take place during operation. Offline techniques, in which the peak temperature information is stored and read-out later, overcome the need for optical access during operation. However, the presently available techniques, such as thermal paint and thermal crystals cannot measure above ∼1400°C. Therefore, a new measurement technique is required to acquire temperature data at extreme temperatures. To meet this challenge, Sensor Coating Systems (SCS) is focused on the development of Thermal History Coatings (THC) that measure temperature profiles in the 900–1600 °C range. THC are oxide ceramics deposited via air plasma spraying process. This innovative temperature profiling technique uses optically active ions in a ceramic host material that start to phosphoresce when excited by light. After being exposed to high temperatures the host material irreversibly changes at the atomic level affecting the phosphorescence properties which are then related to temperature through calibration. This two-part paper describes the THC technology and demonstrates its capabilities for high-temperature applications. In this second part, the THC is implemented on rig components for a demonstration on two separate case studies for the first time. In one test, the THC was implemented on a burner rig assembly on metallic alloys instrumented with thermocouples, provided by Pratt & Whitney Canada. In another test, the THC was applied to environmental barrier coatings developed by NASA, as part of a ceramic-matrix-composite system and heat-treated up to 1500°C. The results indicate the THC could provide a unique capability for measuring high temperatures on current metallic alloys as well as next-generation materials.

Pure Fe and FeMnSi thin films were sputtered on macroporous polypropylene (PP) membranes with the aim to obtain biocompatible, biodegradable and, eventually, magnetically-steerable platforms. Room-temperature ferromagnetic response was observed in both Fe- and FeMnSi-coated membranes. Good cell viability was observed in both cases by means of cytotoxicity studies, though the FeMnSi-coated membranes showed higher biodegradability than the Fe-coated ones. Various strategies to functionalize the porous platforms with transferrin-Alexa Fluor 488 (Tf-AF488) molecules were tested to determine an optimal balance between the functionalization yield and the cargo release. The distribution of Tf-AF488 within the FeMnSi-coated PP membranes, as well as its release and uptake by cells, was studied by confocal laser scanning microscopy. A homogeneous distribution of the drug within the membrane skeleton and its sustained release was achieved after three consecutive impregnations followed by the addition of a layer made of gelatin and maltodextrin, which prevented exceedingly fast release. The here-prepared organic-inorganic macroporous membranes could find applications as fixed or magnetically-steerable drug delivery platforms.

Firing temperatures in gas turbines have seen a steady increase over the years to allow for higher engine efficiencies and a decrease in hazardous emission levels. Conversely, these harsh conditions severely challenge the component lifetime, requiring a trade-off during the design process. Thus, it is crucial to understand temperature distribution across the majority of a component surface (>80%) to verify the design and component durability. While a range of temperature measurement techniques are available, these are primarily focused on lower temperatures, exhibit low durability (thermal paints), require line of sight (pyrometers), are destructive (thermal crystals) and only provide point measurements (thermocouples, thermal crystals). To overcome this challenge, Sensor Coating Systems (SCS) have developed Thermal History Coatings (THCs) to measure temperature profiles in the 900–1600°C range. This new temperature profiling capability records the past maximum exposure temperature in such a way that it can be determined once the component has already cooled down. THCs are comprised of oxide ceramics deposited via Atmospheric Plasma Spraying (APS) to create a robust coating. APS deposition employs several variable parameters; spray settings such as gun power, gas flow or scan rate can affect the particle exposure and thus, the microstructure of the coating and its temperature sensing performance. This two-part paper covers the THCs principles and demonstrates their capabilities for high-temperature applications. This first part shows, for the first time, the influence of APS parameters on luminescent measurements due to changes in the material microstructure. Extensive calibration data was used to develop a new model to relate the APS spray parameters to the luminescent properties in the as-deposited condition and consequent performance as a temperature sensor. The powder composition and the power and gas flow used during deposition were found to be the most influential parameters. The model identified the optimum spray parameters and was used to demonstrate THCs can achieve measurements in excess of 1600°C.

Micrometer-thick cobalt-indium (Co-In) films consisting of self-assembled layers parallel to the cathode plane, and with a periodicity of 175 ± 25 nm, have been fabricated by electrodeposition at a constant current density. These films, which exhibit spatio-temporal patterns on the surface, grow following a layer-by-layer mode. Films cross-sections were characterized by electron microscopies and electron energy loss spectroscopy. Results indicate the spontaneous formation of nanolayers that span the whole deposit thickness. A columnar structure was revealed inside each individual nanolayer which, in turn, was composed of well-distinguished In-and Co-rich regions.Due to the dissimilar magnetic character of these regions, a periodic magnetic nanopatterning was observed in the cross-sectioned films, as shown by magnetic force microscopy studies.