scholarly journals Creep Rupture and Permeability Evolution in High Temperature Heat-Treated Sandstone Containing Pre-Existing Twin Flaws

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6362
Author(s):  
Sheng-Qi Yang ◽  
Jin-Zhou Tang ◽  
Derek Elsworth
Keyword(s):  
Creep Strain ◽  
Stress Level ◽  
Stress Ratio ◽  
Deviatoric Stress ◽  
Threshold Temperature ◽  
Critical Threshold ◽  
Plastic Strains ◽  
Permeability Evolution ◽  
Heat Treated ◽  
Pre Treatment

Utilizing underground coal gasification cavities for carbon capture and sequestration provides a potentially economic and sustainable solution to a vexing environmental and energy problem. The thermal influence on creep properties and long-term permeability evolution around the underground gasification chamber is a key issue in UCG-CCS operation in containing fugitive emissions. We complete multi-step loading and unloading creep tests with permeability measurement at confining stresses of 30 MPa on pre-cracked sandstone specimens thermally heat-treated to 250, 500, 750 and 1000 °C. Observations indicate a critical threshold temperature of 500 °C required to initiate thermally-induced cracks with subsequent strength reduction occurring at 750 °C. Comparison of histories of creep, visco-elastic and visco-plastic strains highlight the existence of a strain jump at a certain deviatoric stress level—where the intervening rock bridge between the twin starter-cracks is eliminated. As the deviatoric stress level increases, the visco-plastic strains make up an important composition of total creep strain, especially for specimens pre-treated at higher temperatures, and the development of the visco-plastic strain leads to the time-dependent failure of the rock. The thermal pre-treatment produces thermal cracks with their closure resulting in increased instantaneous elastic strains and instantaneous plastic strains. With increasing stress ratio, the steady-state creep rates increase slowly before the failure stress ratio but rise suddenly over the final stress ratio to failure. However, the pre-treatment temperature has no clear and apparent influence on steady creep strain rates. Rock specimens subject to higher pre-treatment temperatures exhibit higher permeabilities. The pre-existing cracks close under compression with a coplanar shear crack propagating from the starter-cracks and ultimately linking these formerly separate cracks. In addition, it is clear that the specimens pre-treated at higher temperatures accommodate greater damage.

scholarly journals Reduction in the content of antinutritional substances in pea seeds (Pisum sativum L.) by different treatments

2011 ◽  
Vol 50 (No. 11) ◽  
pp. 519-527 ◽  
Author(s):  
R. Dvořák ◽  
A. Pechová ◽  
L. Pavlata ◽  
J. Filípek ◽  
J. Dostálová ◽  
...  
Keyword(s):  
Pisum Sativum ◽  
Seed Treatment ◽  
Production Traits ◽  
Pisum Sativum L ◽  
Heat Treated ◽  
Pea Seeds ◽  
Reactor Temperature ◽  
Pre Treatment ◽  
Pea Seed ◽  
Representative Samples

The goal of the trial was to reduce the content of antinutritional substances in pea (Pisum sativum L.) seeds in order to enhance its use in livestock nutrition. A variety of field pea (Pisum sativum L.) with a high content of antinutritional substances and favourable production traits (Gotik) was chosen. Native and heat-treated pea seeds were used to collect representative samples (n = 6) for analytical purposes. The technology (V-0 technology, Czech patent No. 285745) was further modified by adjusting the reactor temperature, the duration of exposure to that temperature, and the duration of ageing of the material treated in this way (V-I and V-II technologies). The methodology of treatment is based on exposing pea seeds to vapour, organic acids and selected oxides.The monitored parameters included antinutritional substances. As far as the antinutritional substances were concerned, the content of trypsin inhibitors in native pea seeds (P) was around 15.4 ± 0.5 TIU. After treatment with technologies V-0, V-I, and V-II its activity dropped by 83.8, 80.5 and 83.8%, respectively. The pre-treatment titre of lectins (P) was 717 ± 376. It dropped by 70.3, 35.7 and 73.2% after treatment with technologies V-0, V-I and V-II, respectively. The content of tannins measured by the amount of gallic acid in native pea seeds was 49.1 ± 2.7 mg per kg. It dropped by 41.4, 32.0 and 46.2% after the application of the above-mentioned technologies. The content of indigestible oligosaccharides causing flatulence was less affected by the treatments. The pre-treatment content of raffinose was 9.5 ± 0.5 g/kg. The drop associated with the treatment was 9.5, 6.3 and 10.5%, respectively. The pre-treatment content of stachyose was 21.4 ± 0.8 g/kg and after treatment with technologies V-0 and V-II it dropped by 7.0% and by 16.4%, respectively. The application of technology V-I did not result in a drop in the content of stachyose. The content of verbascose in native pea seeds was 16.1 g/kgand the treatment with technologies V-0; V-I and V-II resulted in a drop by 7.5, 5.6 and 20.5%, respectively. As for the detected phenolic acids, with the exception of caffeic acid, not a drop, but an increase in their content was recorded. Isoflavone oestrogens such as daidzein and genistein also recorded a small increase in their content. The results of the trial lead us to conclude that the above-described methods of pea seed treatment, especially the V-II variant, proved to be useful and can be recommended for practical use.  

On the Interrupted Creep Test Under Low Stress Levels for the Power Law Parameter Extraction

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Bin Yang ◽  
Fu-Zhen Xuan ◽  
Wen-Chun Jiang
Keyword(s):  
Creep Strain ◽  
Stress Level ◽  
Creep Test ◽  
Creep Deformation ◽  
Parameter Extraction ◽  
Tertiary Creep ◽  
Secondary Creep ◽  
Creep Stage ◽  
Strain Data

Abstract Low stress interrupted creep test, as an interim compromise, can provide essential data for creep deformation design. However, there are no clear guidelines on the characterization of the terminating time for interrupted low-stress creep test. To obtain a suitable terminating time in terms of economy and effectiveness, long-term creep strain data of 9%Cr steels are collected from literatures and their creep deformation characterization is analyzed. First, the variations of normalized time and strain of each creep stage with the stress level are discussed. Then, the effect of the terminating time on final fitted results of Norton–Bailey equation is estimated. Third, the relationship between demarcation points at different creep stages and minimum/steady-state creep rate is analyzed. The results indicate that when the creep rupture life is considered as an important factor for creep design, the tertiary creep stage is of greatest significance due to the largest life fraction and creep strain fraction at low stress level. However, the primary and secondary creep stages are of great significance for design due to their larger contribution to 1% limited creep strain. And the long-term secondary creep data could be extrapolated by combining the primary creep strain data obtained from interrupted creep tests with the time to onset of tertiary creep derived from a similar Monkman–Grant relationship.

Characterization of Zirconia for Ceramic Dental Implant Coated with Carbonate Apatite

2019 ◽  
Vol 829 ◽  
pp. 138-144
Author(s):  
Fauziah Erfin ◽  
Rasmi Rikmasari ◽  
Lisda Damayanti ◽  
Andrie Harmaji ◽  
Arief Cahyanto
Keyword(s):  
Dental Implant ◽  
Hydraulic Press ◽  
Carbonate Apatite ◽  
Pellet Size ◽  
Heat Treated ◽  
Temperature Variable ◽  
High Production ◽  
Pre Treatment ◽  
High Production Cost

Zirconia-based dental implant in Indonesia is rarely used, especially due to low demand. High production cost makes the price of each zirconia dental implant piece become expensive. The fabrication process of the dental implant using 3 mol% Yttria-stabilized Zirconia (3YSZ) as a starting powder, or being synthesized using ZrCl3 and YCl4 precursor were costly and complicated. The aim of this study is to investigate morphology and phase analysis in the ceramic dental implant which coated with carbonate apatite (CO3Ap). The industrial 3YSZ powder was compacted using a manual hydraulic press and sintered at 1500°C approximately to 11 mm pellet size. Specimens were pre-treated using 9% hydrofluoric acid (HF) before coated by CO3Ap, while others without treatment as a control. Then, the specimens were dipped into CO3Ap suspension and heat treated with temperature variable of 300°C or 500°C. The fabrication of specimen using manual hydraulic press creates monoclinic phase more than expected, while SEM discovered that the particle size of the specimen was 130-500nm. In conclusion, the effective method to coat the ceramic dental implant with CO3Ap was using 9% HF as a pre-treatment and calcinate in 300°C as confirmed in XRD and EDS.

Enhanced Formability of Age-Hardenable Aluminium Alloys by Incremental Forming of Solution-Treated Blanks

2013 ◽  
Vol 549 ◽  
pp. 164-171 ◽  
Author(s):  
Amirahmad Mohammadi ◽  
Hans Vanhove ◽  
Albert van Bael ◽  
Joost R. Duflou
Keyword(s):  
Precipitation Hardening ◽  
Incremental Forming ◽  
Natural Aging ◽  
Solution Treated ◽  
Treatment Conditions ◽  
Heat Treated ◽  
Initial Hardness ◽  
Aa 2024 ◽  
Cold Worked ◽  
Pre Treatment

The influence of thermal pre-treatment on the formability of a precipitation-hardening aluminium alloy AA-2024 has been studied for three different heat treatment conditions: annealed (O-temper), solution treated and quenched (W-temper) and solution heat treated, quenched and then cold worked (T-temper).The maximum draw angle has been determined and the geometrical accuracy of specific SPIF formed parts has been compared. It is found that the maximum forming angles of the blank formed in O-temper and W-temper conditions show a respective 41% and 32% increase to those of the T-temper condition (initial blank).The hardness of the material reduces significantly after annealing, while SPIF parts formed from W-temper blanks regain their initial hardness after natural aging.

Promotion effect of NP fire retardant pre-treatment on heat-treated poplar wood. Part 1: color generation, dimensional stability, and fire retardancy

Holzforschung ◽  
2017 ◽  
Vol 71 (3) ◽  
pp. 207-215 ◽  
Author(s):  
Demiao Chu ◽  
Jun Mu ◽  
Li Zhang ◽  
Yushuang Li
Keyword(s):  
Dimensional Stability ◽  
Treatment Time ◽  
Fire Hazard ◽  
Fire Retardant ◽  
Surface Color ◽  
Heat Treated ◽  
Combustion Properties ◽  
Long Time ◽  
Pre Treatment ◽  
Wood Part

Abstract Heat treatment (HT) enhances various properties of wood (W), but it takes a relatively long time and WHT is a source of fire hazard. To improve the properties of WHT, Populus beijingensis W. Y. Hsu wood was impregnated with nitrogen-phosphorus (NP) fire retardant (10% aqueous solution) and the effects of the combined NP treatment and HT were observed. Control groups included native wood and samples from WHT200°C, 120 min and WHT220°C, 120 min. The surface color, dimensional stability, and combustion properties of the treated samples were examined. NP pre-treatment intensified the effectivity of HT150°C, where the treatment time decreased by 75%. The decomposition and catalytic dehydration of NP treatment enhanced the dimensional stability and darkened the wood surface. After HT, the NP fire retardant was transformed from dispersive particles into a uniform layer on the inner surfaces of wood. The heat release rate (HRR) decreased by 60.3% and the residual mass (RM) increased by 61.1% in WNP, HT compared to normal WHT200°C poplar.

scholarly journals Pre-treatment of wastes containing keratin in industrial conditions

2008 ◽  
pp. 59-64
Author(s):  
Lili Mézes ◽  
Tibor Bíró ◽  
János Petis ◽  
János Tamás
Keyword(s):  
Retention Time ◽  
Biogas Production ◽  
Degradation Process ◽  
Element Ratio ◽  
Industrial Experiments ◽  
Aeration System ◽  
Heat Treated ◽  
Pre Treatment

The aim of the research was a development of a featherdegradation technology in industrial circumstances. During the experiments we determined the parameters of the critical environmental and technological limitation factors. Because of the high keratin-content the degradation (and composting) of the feather is difficult. With the developed technology huge mass of feather can be used fast and easily in biogas production and in the adjustment of the optimal element ratio of biomass. The industrial experiments were implemented in a 6m3 heatable double-walledtank with stirring-shovels and aeration-system. The degradation process was followed with extinction measurements.According to the experiments that were done the best results were given at the case which was heat-treated at 70°C, was injected with 1% bacteria concentration, and where 1:3 feather:water ratio was set if we consider the effectiveness of degradation and the hydraulical retention time.

scholarly journals EFFECT OF THE HEAT TREATMENT OF Hovenia dulcis Thunb. WOOD ON THE PRODUCTION OF EGP PANELS WITH DIFFERENT ADHESIVES

FLORESTA ◽  
2020 ◽  
Vol 50 (4) ◽  
pp. 1761
Author(s):  
Raquel Marchesan ◽  
Edison Toledo Corrêa dos Santos ◽  
Rosilani Trianoski ◽  
Morgana Cristina França ◽  
Pedro Licio Loiola ◽  
...  
Keyword(s):  
Shear Strength ◽  
Urea Formaldehyde ◽  
External Environment ◽  
Treated Wood ◽  
Polymer Emulsion ◽  
Resorcinol Formaldehyde ◽  
Minimum Standards ◽  
Heat Treated ◽  
Pre Treatment ◽  
Hovenia Dulcis

The objective of this work was to analyze the shear strength of edge-glued panels (EGP) made from the H. dulcis Thunb. wood thermally modified by the VAP HolzSysteme® process. Initially, the Hovenia dulcis samples were heat-annealed by the VAP HolzSysteme® process, and then bonded with Resorcinol-formaldehyde (RF), Melamine-urea-formaldehyde (MUF), Isocyanate Polymer Emulsion (EPI) and Polyvinylacetate (PVAc) and submited to pre-treatments for dry, humid and external environment and without pre-treatment to evaluate the shear strength, 5th percentile and failure in the wood. It was observed a decrease in the shear strength of the thermorrectified H. dulcis wood for all adhesives. All adhesives obtained results superior to the minimum required by the standard EN13354 (2009) for the wood without pre-treatment as for the wood without thermoregulation as well as for the heat treated wood, and may be used for non-structural purposes. However, for the external environment (three cycles) only the MUF adhesive obtained value that meets the minimum standards of the standard, in this way, it is suggested to glue the EGP of H. dulcis without thermortification and with thermorrectification using the MUF adhesive, which has achieved better performance offering greater resistance in dry, wet and external environments.

scholarly journals Creep Behavior of Saturated Clay in Triaxial Test and a Hyperbolic Model

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Bin Xiao ◽  
Minyun Hu ◽  
Peijiao Zhou ◽  
Yuke Lu ◽  
Yong Zhang
Keyword(s):  
Stress Level ◽  
Deviatoric Stress ◽  
Creep Model ◽  
Hyperbolic Model ◽  
Model Parameters ◽  
Total Stress ◽  
Intact Sample ◽  
Creep Analysis ◽  
Creep Characteristics ◽  
Creep Curves

As one of the basic mechanical properties of soil, the creep property of a given type soil is related to stress path, and stress level. In this paper, triaxial shear creep tests under different deviatoric stress levels were performed on both intact sample and the reconstituted sample of clay taken from Hangzhou, China. Based on the Boltzmann linear superposition principle, the creep curves of the clay sample under different levels of deviatoric stress were obtained, and the creep characteristics of the intact sample and the reconstituted sample were compared in both total stress creep analysis and effective stress creep analysis. Furthermore, the creep curves were fitted using a hyperbolic creep model. The results show that (1) under the same stress level, the creep of intact sample evolves more than that of reconstituted sample; (2) the hyperbolic creep model is suited to describe the creep characteristics of intact and reconstituted clay, and the model parameters A s and B s can be linearly correlated to the stress level D r ; (3) for the application of the hyperbolic model, the total stress analysis works better, and the model parameters A s and B s can be determined by a linear relationship with Dr.

scholarly journals Properties and behavior of light hydrophobic concrete

2021 ◽  
Vol 17 (3) ◽  
pp. 299-307
Author(s):  
Makhmud Kharun ◽  
Armin Ehsani ◽  
Shahin Nasimi ◽  
Tesfaldet H. Gebre
Keyword(s):  
Lightweight Concrete ◽  
Three Dimensional ◽  
Polymeric Materials ◽  
Surface Hydrophobicity ◽  
Coupling Agents ◽  
Acrylic Polymer ◽  
Heat Treated ◽  
Pre Treatment ◽  
The Right ◽  
And Behavior

In concrete mixing plan, we usually encounter a combination of aggregates including sand, the amount of cement, which is actually the criterion of concrete grade, and the volume of water consumed. Changes in the quality and quantity of these components actually create the usual types of concrete. But the attitude that formed the basis of this research is based on the change in the nature of the components of the concrete mixing design. Removal of water and cement from the mixing plan and replacement of polymeric materials as well as the use of mixed LECA aggregates instead of aggregates is the basis of this research. In this paper, by examining and selecting LECA grain style and pre-treatment (hydrophobicity and coupling), in a constant ratio of resin, concrete samples were selected from three dimensional categories. After making the samples, flexural strength test was performed on them and the results were analyzed. Various compounds and processes have so far been proposed in the lightweight concrete mixing scheme. The distinctive point of this study is the use of lightweight expanded clay concrete with heat-treated acrylic polymer (crosslinking constituents) and related coupling agents. It is also important to select and apply the right amount of hydrophobic nanoparticles for hydrophilic surface hydrophobicity. Hydrophobicity was possible due to the non-polar nature of the acrylic polymer and the use of hydrophobic nanomaterials.

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