scholarly journals Mobility of Radiogenic Helium in Amphibole

Minerals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 27
Author(s):  
Igor Tolstikhin ◽  
Sergei Tarakanov ◽  
Vitalii Kolobov ◽  
Maria Gannibal
Keyword(s):  
Thermal Expansion ◽  
Size Distribution ◽  
Heating Rate ◽  
Diffusion Flux ◽  
Domain Size ◽  
Sharp Peak ◽  
Crystalline Lattice ◽  
Slow Heating ◽  
Fast Heating ◽  
Tensile Stresses

Recently experiments on He extraction from an amphibole by the incremental heating unexpectedly revealed that the He release pattern depends on the heating rate. During slow heating (~4 K·min−1) of the amphibole grains, one smooth peak of the He flux from the mineral was observed; in contrast, during fast heating (~40 K·min−1) an additional sharp peak appeared at a temperature about 750 °C. In order to explain these observations, we developed a model of He diffusion from the amphibole, which allowed the calculated He fluxes from the mineral to be reconciled with those observed. From the modelling we derived: (i) the helium diffusion domain size distribution, and evolution of the distribution in the course of incremental heating; (ii) occurrence of the tensile stresses, operating under enhanced temperatures above 700 °C. The stresses are different in sites with the different local thermal expansion of the crystalline lattice and they increase the He diffusion flux. The model can be applied to other minerals (materials).

scholarly journals Pore Size Distribution and Microstructure of Oil Palm Shell Heat Treated at 300 C Followed by Slow or Fast Heating Treatment

2020 ◽  
Vol 9 (1) ◽  
pp. 15-25
Author(s):  
Joko Sulistyo ◽  
Toshimitsu Hata ◽  
Yuji Imamura ◽  
Purnomo Darmaji ◽  
Sri Nugroho Marsoem
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Oil Palm ◽  
Slow Heating ◽  
Fast Heating ◽  
Palm Shell ◽  
Oil Palm Shell ◽  
Heat Treated ◽  
Heating Treatment

Pore size distribution and microstructure development of oil palm shell heat treated at 300ºC and treated at 300ºC and recarbonization at 600ºC followed by slow- or fast heating treatment up to 700ºC were investigated by small angle X-ray scattering (SAXS), N2 gas adsorption and Raman spectroscopy. On oil palm shell heat-treated at 300ºC, slow heating treatment gave the widening micropore along with the ordering microstructure; but fast heating treatment produced charcoal with a narrow diameter of micropore with wider pore size distribution and the disordering microstructure. On oil palm shell heat treated at 300ºC and recarbonization at 600ºC, slow heating treatment contributed on the opening new micropore with ordering microstructure, but some parts of micropore showing inaccessible for N2 gas. Meanwhile, fast heating treatment with the heating rate from 75 to 250ºC/min increased BET surface area with similar pore size distribution and the disordering microstructure.

scholarly journals Explosive Spalling Behavior of Single-Sided Heated Concrete According to Compressive Strength and Heating Rate

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6023
Author(s):  
Euichul Hwang ◽  
Gyuyong Kim ◽  
Gyeongcheol Choe ◽  
Minho Yoon ◽  
Minjae Son ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Vapor Pressure ◽  
Heating Rate ◽  
Heated Surface ◽  
Concrete Surface ◽  
Slow Heating ◽  
Explosive Spalling ◽  
Fast Heating ◽  
Moisture Migration ◽  
Heated Concrete

In this study, the effects of heating rate and compressive strength on the spalling behavior of single-sided heated ring-restrained concrete with compressive strengths of 60 and 100 MPa were investigated. The vapor pressure and restrained stress inside the concrete were evaluated under fast- and slow-heating conditions. Regardless of the heating rate, the concrete vapor pressure and restrained stress increased as the temperature increased, and it was confirmed that spalling occurred in the 100-MPa concrete. Specifically, it was found that moisture migration and restrained stress inside the concrete varied depending on the heating rate. Under fast heating, moisture clogging and restrained stress occurred across the concrete surface, causing continuous surface spalling for the 100-MPa concrete. Under slow heating, moisture clogging occurred, and restrained stress continuously increased in the deep area of the concrete cross-section owing to the small internal temperature difference, resulting in explosive spalling for the 100-MPa concrete with a dense internal structure. Additionally, while the tensile strength of concrete is reduced by heating, stress in the heated surface direction is generated by restrained stress. The combination of stress in the heated concrete surface and the internal vapor pressure generates spalling. The experimental results confirm that heating rate has a significant influence on moisture migration and restrained stress occurrence inside concrete, which are important factors that determine the type of spalling.

scholarly journals On the thermal consolidation of Boom clay

2000 ◽  
Vol 37 (2) ◽  
pp. 343-354 ◽  
Author(s):  
Pierre Delage ◽  
Nabil Sultan ◽  
Yu Jun Cui
Keyword(s):  
Thermal Expansion ◽  
Waste Disposal ◽  
Volume Change ◽  
Free Water ◽  
Radioactive Waste Disposal ◽  
Slow Heating ◽  
Intrinsic Permeability ◽  
Fast Heating ◽  
Boom Clay ◽  
Thermal Consolidation

When a mass of saturated clay is heated, as in the case of host soils surrounding nuclear waste disposal at great depth, the thermal expansion of the constituents generates excess pore pressures. The mass of clay is submitted to gradients of pore pressure and temperature, hydraulic and thermal flows, and changes in its mechanical properties. In this work, some of these aspects were experimentally studied in the case of Boom clay to help predict the response of the soil, in relation to investigations in the Belgian underground laboratory at Mol. Results of slow-heating tests with careful volume change measurements showed that a reasonable prediction of the thermal expansion of the clay-water system was obtained by using the thermal properties of free water. Despite the density of Boom clay, no significant effect of water adsorption was observed. The thermal consolidation of Boom clay was studied through fast-heating tests. A simple analysis shows that the hydraulic and thermal transfers are uncoupled. Experimental results from fast-heating tests showed that the consolidation coefficient does not change significantly with increased temperature, due to the opposite effect of increasing permeability and decreasing porosity. The changes of permeability with temperature were investigated by running constant head measurements at various temperatures. An indirect analysis, based on estimation of the coefficient of volume change mv, showed that the indirect method of estimating the permeability from consolidation tests should be considered carefully. Intrinsic permeability values were derived by considering the change of the viscosity of free water with temperature. A unique relationship between the intrinsic permeability and the porosity was observed, with no dependence on temperature, confirming that the flow involved in the permeability test only concerns free water.Key words: clays, thermal consolidation, adsorbed water, permeability, temperature effects, radioactive waste disposal.

Physical and Mechanical Properties of Fired Clay Bricks Incorporated with Cigarette Butts: Comparison between Slow and Fast Heating Rates

2013 ◽  
Vol 421 ◽  
pp. 201-204
Author(s):  
Aeslina binti Abdul Kadir ◽  
Abbas Mohajerani
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Heating Rate ◽  
Initial Rate ◽  
Physical And Mechanical Properties ◽  
Slow Heating ◽  
Firing Process ◽  
Heating Rates ◽  
Fast Heating ◽  
Rate Of Absorption

In general, firing process in brick manufacturing could affect the properties, colours and appearance of the brick. The main purpose of this study was to evaluate the effect of different heating rates on physical and mechanical properties during the firing of standard bricks and bricks incorporated with cigarette butt (CB). In this investigation, two different heating rates were used: slow heating rate (2oC min-1) and fast heating rate (5oC min-1). Samples were fired in solid forms from room temperature to 1050oC. All bricks were tested for their physical and mechanical properties including compressive strength, initial rate of absorption and density. Higher heating rates decrease compressive strength value but slightly increase the initial rate of absorption and density properties respectively. In conclusion, higher heating rates are able to produce adequate physical and mechanical properties especially for CB Brick.

scholarly journals Peach and Nectarine Quality Following Treatment with High-temperature Forced Air Combined with Controlled Atmosphere

HortScience ◽  
2005 ◽  
Vol 40 (5) ◽  
pp. 1425-1430 ◽  
Author(s):  
David Obenland ◽  
Paul Neipp ◽  
Bruce Mackey ◽  
Lisa Neven
Keyword(s):  
Heating Rate ◽  
Fruit Quality ◽  
Prunus Persica ◽  
Total Duration ◽  
Storage Period ◽  
Soluble Solids ◽  
Slow Heating ◽  
Controlled Atmosphere ◽  
Heating Rates ◽  
Fast Heating

Yellow- and white-fleshed peach [Prunus persica (L.) Batsch] and nectarine [Prunus persica (L.) Batsch var. nectarina (Ait) Maxim.] cultivars of mid- and late-season maturity classes were subjected to combined controlled atmosphere–temperature treatment system (CATTS) using heating rates of either 12 °C/hour (slow rate) or 24 °C/hour (fast rate) with a final chamber temperature of 46 °C, while maintaining a controlled atmosphere (CA) of 1 kPa oxygen and 15 kPa carbon dioxide. Fruit seed surface temperatures generally reached 45 °C within 160 minutes and 135 minutes for the slow and fast heating rate, respectively. The total duration of the slow heating rate treatment was 3 hours, while 2.5 h was required for the fast heating rate treatment. Following treatment the fruit were stored at 1 °C for either 1, 2, or 3 weeks followed by a ripening period of 2 to 4 d at 23 °C and subsequent evaluation of fruit quality. Fruit quality was similar for both heating rate treatments. Compared with the untreated controls, CATTS fruit displayed higher amounts of surface injury, although increased injury was only an important factor to marketability in cultivars that had high amounts of surface injury before treatment. The percentage of free juice in the flesh was slightly less in CATTS fruit early in storage but was often greater in treated fruit toward the end of the storage period. Slower rates of softening during fruit ripening were apparent in CATTS fruit. Soluble solids, acidity, weight loss and color all were either not affected or changed to a very small degree as a result of CATTS. Members of a trained sensory panel preferred the taste of untreated fruit over fruit that had been CATTS but the ratings of treated and nontreated fruit were generally similar and it is unclear whether an average consumer could detect the difference. Although further work needs to be done regarding the influence of CATTS on taste, it otherwise appears that CATTS does not adversely affect the marketability of good quality fruit and therefore shows promise as a nonchemical quarantine treatment for peaches and nectarines.

scholarly journals Microstructure, Grain Growth and Hardness of Nanostructured Ferritic ODS Steel Powder during Annealing

2021 ◽  
Author(s):  
Krzysztof Nowik ◽  
Zbigniew Oksiuta
Keyword(s):  
Dislocation Density ◽  
Size Distribution ◽  
Hot Isostatic Pressing ◽  
Domain Size ◽  
Oxide Dispersion Strengthened ◽  
Alloy Formation ◽  
Nanocrystalline State ◽  
Ferritic Alloy ◽  
Ods Steel ◽  
Double Phase

AbstractNanocrystalline oxide-dispersion strengthened ferritic alloy formation and its annealing behavior were examined through modern X-ray diffraction pattern analysis and supplemented by microhardness and microscopic measurements. The basic microstructure features, with particular emphasis on evolution of domain size distribution and defect content during mechanical and thermal treatment, were quantified via the whole powder pattern modeling approach. The microstructure of the powdered alloy, formed during mechanical alloying, evolved toward nanocrystalline state consisting of narrow dispersion of very fine crystallites with substantial dislocation density, which exhibited relatively high stability against elevated temperature. It was shown that crystallite size is seriously sustained by the grain-boundary strain, therefore coarsening of grains begins only after the density of dislocations drops below certain level. Obtaining correct results for the annealing-related data at specific temperature range required the incorporation of the “double-phase” model, indicating possible bimodal domain size distribution. The dislocation density and grain size were found not to be remarkably affected after consolidation by hot isostatic pressing.

Microstructural development of ZnO using a rate-controlled sintering dilatometer

1996 ◽  
Vol 11 (3) ◽  
pp. 671-679 ◽  
Author(s):  
Gaurav Agarwal ◽  
Robert F. Speyer ◽  
Wesley S. Hackenberger
Keyword(s):  
Thermal Expansion ◽  
Heating Rate ◽  
Grain Growth ◽  
Microstructural Development ◽  
Constant Heating Rate ◽  
Temperature Determination ◽  
Grain Sizes ◽  
Rate Controlled ◽  
Temperature Controlled ◽  
Constant Heating

Rate-controlled sintering (RCS) of isostatically pressed particulate compacts of ZnO showed lower average grain sizes and intragranular pore densities than constant heating rate temperature controlled sintering. Valid comparisons of this form could only be made after corrections to hardware and software which reduced specimen creep under dilatometer pushrod load, nonuniform pushrod expansion, reproducible specimen temperature determination, thermal expansion during sintering, and instantaneous termination of sintering at the specified end of RCS. The improved microstructures from RCS were attributed to maximized efficiency of densification, optimizing the time and temperatures permitted for grain growth.

Study on the residual performance of RC beams exposed to processed temperatures and fire

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sachin Vijaya Kumar ◽  
N. Suresh
Keyword(s):  
Failure Modes ◽  
Elevated Temperatures ◽  
Slow Heating ◽  
Maximum Temperature ◽  
Rc Beams ◽  
Heating Rates ◽  
Fast Heating ◽  
Content Type ◽  
Temperature Increment ◽  
Residual Performance

PurposeThe Reinforced Concrete(RC) elements are known to perform well during exposure to elevated temperatures. Hence, RC elements are widely used to resist the extreme heat developing from accidental fires and other industrial processes. In both of the scenarios, the RC element is exposed to elevated temperatures. However, the primary differences between the fire and processed temperatures are the rate of temperature increase, mode of exposure and exposure durations. In order to determine the effect of two heating modalities, RC beams were exposed to processed temperatures with slow heating rates and fire with fast heating rates.Design/methodology/approachIn the present study, RC beam specimens were exposed to 200 °C, to 800 °C temperature at 200 °C intervals for 2 h' duration by adopting two heating modes; Fire and processed temperatures. An electrical furnace with low-temperature increment and a fire furnace with standard time-temperature increment is adapted to expose the RC elements to elevated temperatures.FindingsIt is observed from test results that, the reduction in load-carrying capacity, first crack load, and thermal crack widths of RC beams exposed to 200 °C, and 600 °C temperature at fire is significantly high from the RC beams exposed to the processed temperature having the same maximum temperature. As the exposure temperature increases to 800 °C, the performance of RC beams at all heating modes becomes approximately equal.Originality/valueIn this work, residual performance, and failure modes of RC beams exposed to elevated temperatures were achieved through two different heating modes are presented.

Sign in / Sign up

Export Citation Format

Share Document