Maximum Test Temperature Research Articles

High-Temperature Measurement Technology for Microwave Surface Resistance of Metal Materials

The resonant cavity method is a commonly used method for high-temperature testing of the complex permittivity of dielectric materials. When a resonant cavity is used for high-temperature testing, the microwave surface resistance of the cavity metal material will deteriorate due to factors such as oxidation reaction and thermal fatigue, resulting in a decrease in testing accuracy and repeatability. Therefore, when designing a high-temperature resonant cavity, the temperature response characteristics of the microwave surface resistance of the cavity metal material should be obtained in advance. In this paper, a high-temperature measurement method of microwave surface resistance of metal materials based on a separate cylindrical resonator is proposed, a mathematical model of microwave surface resistance inversion based on the resonator quality factor is established, and a high-temperature measurement system of microwave surface resistance is integrated. The reliability of the proposed method and system is verified through simulation and experiment. The measurement frequency covers 7-18 GHz, and the maximum test temperature reaches 500°C. Systematic error of microwave surface resistance measurement at room temperature is less than 3%.

Fiber Optic Temperature Sensor System Using Air-Filled Fabry-Pérot Cavity with Variable Pressure.

We report a high-resolution fiber optic temperature sensor system based on an air-filled Fabry-Pérot (FP) cavity, whose spectral fringes shift due to a precise pressure variation in the cavity. The absolute temperature can be deduced from the spectral shift and the pressure variation. For fabrication, a fused-silica tube is spliced with a single-mode fiber at one end and a side-hole fiber at the other to form the FP cavity. The pressure in the cavity can be changed by passing air through the side-hole fiber, causing the spectral shift. We analyzed the effect of sensor wavelength resolution and pressure fluctuation on the temperature measurement resolution. A computer-controlled pressure system and sensor interrogation system were developed with miniaturized instruments for the system operation. Experimental results show that the sensor had a high wavelength resolution (<0.2 pm) with minimal pressure fluctuation (~0.015 kPa), resulting in high-resolution (±0.32 ℃) temperature measurement. It shows good stability from the thermal cycle testing with the maximum testing temperature reaching 800 ℃.

Additive Manufacturing: Corrosion Proofing by Infusion of Interstitial Solute—Exemplified for Alloy 22

The corrosion resistance of Cr-containing alloy parts made by additive manufacturing can be significantly improved by a post-treatment of gas-phase-based infusion of concentrated interstitial solute (carbon and nitrogen). We demonstrate this universal approach for the example of low-temperature nitrocarburization by solid-reagent pyrolysis applied to Alloy 22 (UNS N06022) parts made by laser powderbed fusion. We show that the post-treatment improves the crevice-corrosion resistance of these parts, as well as the corrosion resistance of corresponding parts made from wrought Alloy 22 to surpass the maximum crevice corrosion test temperature specified in ASTM G48-D, whereas non-treated samples typically fail well below. Similarly, cyclic potentiodynamic polarization testing (ASTM G61-86) demonstrates that the post-treatment makes the additively manufactured alloy and the wrought alloy more corrosion-resistant than the non-treated wrought alloy.

Produced water desalination using high temperature membranes

Produced water is the largest source of wastewater in the oil and gas industry. One of the approaches to manage excess produced water is to increase its reuse opportunities using desalination technologies such as reverse osmosis. This article presents an experimental study using high temperature reverse osmosis membranes to treat produced water in a relatively high temperature range. Synthetic water was prepared using the produced water formula containing 10,600 mg/L of Total Dissolved Solids (TDS) and 83 mg/L of boron. Different pH and temperature conditions were evaluated to simulate the field operation conditions. The selected membrane module demonstrated high boron rejection at the test condition of pH 11 in the temperature range of 25 °C–60 °C. More than 98% of boron rejection was achieved at the maximum testing temperature of 60 °C. The membrane software was calibrated with the lab test data. Further lab studies using field produced water at 55 °C showed consistent results for boron and TDS rejections. Calibrated membrane software was used to perform system-level design at various recovery rates; the projected water quality and pressures had good alignment with the lab test results. The consistent membrane performance in this study provides an opportunity to undertake future field study using the RO membranes to treat high temperature produced water.

Influence of thermomechanical fatigue loading conditions on the nanostructure of secondary hardening steels

Abstract Dual hardening steels reach their well-balanced mechanical properties in terms of strength and toughness through the combination of secondary hardening carbide and intermetallic particle precipitation. This characteristic profile makes them well suited for hot-work applications. In this study, out-of-phase thermomechanical fatigue tests, recreating operating conditions present during hot-work applications, were performed on a dual hardening steel and a 5% Cr martensitic hot-work tool steel. Via high resolution analysis utilizing atom probe tomography and transmission electron microscopy, the behaviour of the different precipitate populations under combined thermal and mechanical loading conditions were compared. Coarsening of the different precipitates and partial dissolution of the intermetallic compounds was observed. It could be shown that with rising maximum fatigue test temperature, the dual hardening steel reaches an increased lifetime caused by its higher tempering resistance.

Experimental research on the permeability of fractured-subsequently-filled granite under high temperature-high pressure and the application to HDR geothermal mining

To reveal the physical characteristics of fractured-subsequently-filled granite and to guide hot dry rock (HDR) mining, this paper studied the permeability at 500 °C and 1000 m hydrostatic pressure of the parent rock (type Ⅰ granite), hydrothermal fluid backfill (type Ⅱ granite), cementation interface between the backfill and the parent rock laterally positioned through the specimen (type III granite), and cementation interface between the backfill and the parent rock longitudinally positioned through the specimen (type IV granite). The results show that the threshold temperature of the permeability changes for the four types of granite (i.e., types I, II, III, and IV) are 300 °C, 200 °C, 300 °C and 250 °C, respectively. From the threshold temperature to the maximum test temperature, the permeability of type I, II, III and IV granite increases exponentially by 1, 2, 2 and 3 orders of magnitude, reaching 10−6 D, 10−4 D, 10−5 D and 10−4 D, respectively. Micro-observation results of the micro-structures show that thermal cracking of the heterogeneous rock mass is the main reason for the increase in permeability of type I and III granite; the low strength and deteriorated mechanical properties caused by dissolution are the main reasons for the permeability of type II granite to significantly exceed that of type I and III granite; the extreme heterogeneity and the deteriorated mechanical properties of the backfill together indicate that type IV granite has the best permeability. During reservoir construction by hydraulic fracturing in fractured-subsequently-filled granite, the flow of the fracturing water along the direction perpendicular to the cementation interface is limited. However, when the reservoir temperature exceeds 250 °C, the backfill strengthened by the cementation near the cementation interface restores the weak-plane structure characteristics; when the reservoir temperature exceeds 400 °C, the thermal cracking fractures near the cementation interface interconnect with each other along the cementation interface to form a permeability channel. Therefore, the fracturing water in the backfill can easily flow along the cementation interface. Eventually, reservoir construction in fractured-subsequently-filled granite can greatly reduce engineering costs, increase reservoir water-rock heat exchange areas and improve heat exchange efficiency, which provides a new technical and theoretical approach for deep HDR geothermal exploitation.

Comparative Study on Plastic Materials as a New Source of Energy

The pyrolysis can be an attractive way to reduce the plastic waste and, in the same time, to obtain alternative conventional fuels. In this respect, four polymers (low-density polyethylene, high-density polyethylene, propylene and polystyrene) were used in the pyrolysis process. The experiments were carried out by using an in-house plant, which allowed a maximum test temperature of 450 �C. The product oil and the derived gas from the pyrolysis process were evaluated using different techniques, such as elemental analysis (EA), calorimetry, gas chromatography (GC), gas chromatography coupled with mass spectrometry (GC-MS). Furthermore, for a comparative study two catalysts, zeolite and lignite, were also used for the pyrolysis process, in order to observe their influences on the final products. The higher heating value obtained for the oil was in the 40.17-45.35 MJ/kg range, acceptable for the use of these oil as an alternative fuel for diesel engine. Also, the sulphur content from the obtained oil does not cause environment problems, being lower than the allowed limits (10 mg/L). In addition, the pyrolysis derived gas was rich in hydrocarbons, conducting to a high calorific value, in the 73.42 - 121.18 MJ/kg range.

Design and Implementation of Distributed Ultra-High Temperature Sensing System With a Single Crystal Fiber

Modern high-temperature processes, such as fossil energy production, nuclear reactors, and chemical reactors lack robust, distributed sensing systems to map temperatures in these high-value harsh-environment systems. Regular silica-fiber-based distributed temperature sensing systems usually only operate at temperatures below about 800 °C. In this paper, we present the design, implementation, and testing of a distributed ultra-high temperature sensing system using Raman scattering intensity, which operates from room temperature to above 1400 °C. Consideration is given to the impacts of thermal radiation, fluorescence, and the multimode nature of unclad single-crystal fiber to optimize the system. Results from picosecond and sub-nanosecond lasers were compared. Measurements were taken with a ∼2 m sapphire optical fiber, which represents the longest commercially available length. A spatial resolution of 12.4 cm and position standard deviation of 0.28 mm were achieved up to the maximum testing temperature of 1400 °C, which is a new record for distributed temperature sensing systems.

Microstructural evolution and functional fatigue of a Ti–25Ta high-temperature shape memory alloy

Abstract

Ductile behavior of fine-grained, carbon-bonded materials at elevated temperatures

Carbon-bonded materials are widely used in refractory applications because of their unique chemical, physical, and mechanical properties at high temperatures. The mechanisms of their high-temperature deformation are, however, unclear. The present study reveals new results from mechanical testing of both fine-grained, carbon-bonded alumina and graphite (ISEM 8) observed at temperatures of up to 1500 °C in an inert atmosphere. The results were achieved by means of microstructural investigations by scanning electron microscopy. For Al2O3-C, a pronounced maximum strength vs. testing temperature occurred at 1300–1400 °C, with a change from brittle to ductile behavior. In contrast, graphite showed an increase in strength until 1500 °C and no evidence of ductile deformation. A model based on the differences in the coefficients of thermal expansion of the components is presented to explain this phenomenon. In addition, Raman spectroscopy revealed the formation of graphitic structures due to testing at 1500 °C.

Thermal conductivity of refractory glass fibres

In the present study, the current international standards and corresponding apparatus for measuring the thermal conductivity of refractory glass fibre products have been reviewed. Refractory glass fibres are normally produced in the form of low-density needled mats. A major issue with thermal conductivity measurements of these materials is lack of reproducibility in the test results due to transformation of the test material during the test. Also needled mats are inherently inhomogeneous, and this poses additional problems. To be able to compare the various methods of thermal conductivity measurement, a refractory reference material was designed which is capable of withstanding maximum test temperatures (1673 K) with minimum transformation. The thermal conductivity of this reference material was then measured using various methods according to the different standards surveyed. In order to compare different materials, samples have been acquired from major refractory glass fibre manufacturers and the results have been compared against the newly introduced reference material. Materials manufactured by melt spinning, melt blowing and sol–gel have been studied, and results compared with literature values.

Development of a CuNiCrAl Bond Coat for Thermal Barrier Coatings in Rocket Combustion Chambers

The lifetime of rocket combustion chambers can be increased by applying thermal barrier coatings. The standard coating systems usually used in gas turbines or aero engines will fail at the bond coat/substrate interface due to the chemical difference as well as the different thermal expansion between the copper liner and the applied NiCrAlY bond coat. A new bond coat alloy for rocket engine applications was designed previously with a chemical composition and coefficient of thermal expansion more similar to the copper substrate. Since a comparable material has not been applied by thermal spraying before, coating tests have to be carried out. In this work, the new Ni-30%Cu-6%Al-5%Cr bond coat alloy is applied via high velocity oxygen fuel spraying. In a first step, the influence of different coating parameters on, e.g., porosity, amount of unmolten particles, and coating roughness is investigated and a suitable parameter set for further studies is chosen. In a second step, copper substrates are coated with the chosen parameters to test the feasibility of the process. The high-temperature behavior and adhesion is tested with laser cycling experiments. The new coatings showed good adhesion even at temperatures beyond the maximum test temperatures of the NiCrAlY bond coat in previous studies.

Vacuum-arc chromium-based coatings for protection of zirconium alloys from the high-temperature oxidation in air

Multilayer Cr–Zr/Cr/Cr–N coatings for protection of zirconium alloys from the high-temperature oxidation in air have been obtained by the vacuum-arc evaporation technique with application of filters for plasma cleaning from macroparticles. The effect of the coatings on the corrosion resistance of zirconium alloys at test temperatures between 660 and 1100 °C for 3600 s has been investigated. The thickness, structure, phase composition, mechanical properties of the coatings and oxide layers before and after oxidation tests were examined by scanning electron microscopy, X-ray diffraction analysis and nanoindentation technique.It is shown that the hard multilayer coating effectively protects zirconium from the oxidation in air for 1 h at test temperatures. As a result of the oxidation in the coating the CrO and Cr2O3 oxides are formed which reduce the oxygen penetration through the coating. At maximum test temperature of 1100 °C the oxide layer thickness in the coating is about 5 μm. The tube shape remains unchanged independent of alloy type. It has been found that uncoated zirconium oxidizes rapidly throughout the temperature range under study. At 1100 °C a porous monoclinic ZrO2 oxide layer of ≥120 μm is formed that leads to the deformation of the samples, cracking and spalling of the oxide layer.

Temperature response of a high power lithium-ion battery subjected to high current discharge

Commercial LiFePO4 batteries were tested with several discharge currents (15, 20, 25, 30 and 35 A). Five k-type thermocouples were placed at the surface of each battery to evaluate the temperature distribution and electrochemical behaviour. The experiment showed that the maximum surface temperature reached 76·5°C when the current was 35 A, and the time of the maximum test temperature over 50°C was 84·42% of the total time. Supported by ANSYS software based on the implicit finite difference, the chemical reaction around the electrode, especially in anode, was more active than other places, which appeared to be higher temperature. To design a successful battery thermal management system, it is needful to study the battery temperature distribution and electrochemical behaviour. Statistical studies indicate that the maximum deviation between experimental and simulated values of the temperature distribution is ±10%.

J0310101 オーステナイト系鋳鋼の熱疲労き裂進展と温度条件

Effect of maximum test temperature on crack propagation behavior of an Austenitic cast steel during Thermo-Mechanical Fatigue (TMF) tests was explored under the In-Phase(IP) and Out-of-Phase(OP) conditions. The behavior was comprared with that of isothermal low cycle fatigue. The experimental results clearly showed that additional mechanism(s) mechanism to pure fatigue begun to work, when the maximum temperature get higher enough. It was also shown that not only the mechanical factors but the microstuructural features;e.g., microsegragation around dendritic boundaries, played an important role in the crack progation process.

Influence of long isothermal aging on the limiting mechanical and relaxation properties of glass-filled PA-6

The results of long-term isothermal tests of samples of glass-filled PA-6 at 60–150°C are presented. It has been shown that an irreversible change in its strength properties occurs at T ≥ 150°C. A detailed study of the mechanical relaxation characteristics has revealed that the mechanism of the relaxation process in the polyamide changes at 140°C. Thus, the maximum environmental testing temperature for products made from glass-filled PA-6 should not exceed 140°C.

Tribological Properties of Arc-Evaporated NbAlN Hard Coatings

Nb1−xAlxN hard coatings were synthesised by cathodic arc-evaporation with different Al contents to study its influence on the tribological properties. Ball-on-disc tests at temperatures up to 700 °C were performed and the recorded coefficient of friction was generally in the range from 0.8 to 1.0. Subsequent analysis of the coating wear track and the counterpart wear scar by optical profilometry and Raman spectroscopy revealed details on the wear behaviour of the tested coatings. The best wear performance for the Nb-rich coatings was in the temperature range of 300–500 °C, whereas at the maximum testing temperature the higher oxidation resistance with increasing Al content was beneficial in terms of wear resistance.

Structure and tribological properties of AlCrTiN coatings at elevated temperature

In this study, we analyzed the high temperature tribological behavior of AlCrTiN coatings deposited on WC substrates by low cathodic arc technique. The coatings chemical composition, Al 31at.%, Cr 16at.%, Ti 7at.% and N 46at.%, and the bonding state were evaluated by X-ray photoelectron spectroscopy. The mechanical properties of the coatings were studied by scratch-test and nanohardness depth sensing indentation. The morphology of the coatings surface, ball scars, wear tracks and wear debris as well as the oxidized samples was examined by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The structure was analyzed using X-ray diffraction (XRD). Wear testing was carried out using a high temperature tribometer (pin-on-disc) with alumina balls as counterparts. The evaluation of the friction coefficient with the number of cycles (sliding distance) was assessed at different temperatures and the wear rates of the coatings and balls were determined; the maximum testing temperature was 800°C. The coating showed an excellent thermal stability and wear resistance. The friction reached a maximum at 500°C and then decreased, whereas the wear rate was negligible up to 600°C and increased significantly at higher temperatures.

Serrated Flow and Enhanced Ductility in Coarse-Grained Al-Mg Alloys

Conventionally, superplasticity requires the presence of a fine-grained microstructure to enable grain-boundary sliding to take place during deformation. However, coarse-grained materials have also been shown to exhibit higher than normal amounts of ductility, provided they possess a high-enough strain rate sensitivity. In this work, coarse-grained Al-3 pct Mg, Al-5 pct Mg, and AA 5056 alloys were tested for enhanced ductility. The dependence of flow stress on temperature was found to display some unusual characteristics; these were interpreted as resulting from the occurrence of dynamic strain aging (DSA). In these materials, a local peak in elongation coincided with the presence of an unusual peak in rate sensitivity. This region of higher than normal rate sensitivity was coupled with the usual region of negative rate sensitivity found in DSA-prone materials, such as the Al-Mg alloys. A maximum ductility of 170 pct was recorded at 723 K (450 °C) and a strain rate of 5 × 10−2 seconds−1 was found in the vicinity of the rate sensitivity peak. This was found to increase to nearly 300 pct when the gage length was shortened. These peaks in elongation occurred below the maximum test temperatures.

Evaluation of the Variability of |E*| with Field Procured Hot Mix Asphalt Concrete Mixtures

ABSTRACT The dynamic complex modulus test is quickly coming into the mainstream of practice for research purposes and implementation by owner/agencies. Past research projects have developed estimated limits of accuracy for laboratory mixed/laboratory compacted specimens, however there is little information for field mixed/laboratory compacted specimens. The dynamic complex modulus test was conducted on each of 17 field mixed/laboratory compacted mixtures with various volumetric properties and three replicate specimens to evaluate test variability. Included were factors believed to affect the results and variability of the dynamic modulus test. Statistical analysis was performed to determine the significance of the factors. The results of the analysis showed that three main factors were significant contributors to the variability of the dynamic complex modulus test results (nominal maximum aggregate size, test temperature, and binder grade). Six factors were checked and validated to be the main contributors in the dynamic modulus values (air voids, asphalt content, frequency, temperature, use of recycled asphalt pavement, and binder grade).