scholarly journals The Coupled Effect of Temperature and Carbonation on the Corrosion of Rebars in the Simulated Concrete Pore Solutions

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Jiezhen Hu ◽  
Xuequn Cheng ◽  
Xiaogang Li ◽  
Peichang Deng ◽  
Gui Wang
Keyword(s):  
High Temperature ◽  
Electrochemical Impedance ◽  
Ph Value ◽  
Concrete Structures ◽  
Open Circuit ◽  
Effect Of Temperature ◽  
Coupled Effect ◽  
Latitude Region ◽  
Higher Temperature ◽  
Lower Temperature

The reinforced concrete structures have to survive high temperature and carbonation at low latitude region. The research on the effect of temperature and the effect of carbonation are vital to the corrosion of the rebars in concrete structures. The coupled effect of temperature and carbonation on the corrosion of rebars was researched by using the open circuit potential (OCP), the electrochemical impedance spectroscopy (EIS), and the potentiodynamic polarization (PP) measurement in the simulated concrete pore solutions (SPSs). The high temperature environment is conducive to the formation of passivated surface of rebars in SPSs, but the dissolution velocity of passivated surface is higher. The rebars have the greater capacity of passivity at lower temperature. The corrosion rate of rebars at higher temperature is smaller in moderate pH value (10.6) SPSs. The rebars suffer from serious corrosion in the pH = 9.6 SPSs at 318 K temperature.

Experimental Study of Propagation Stage of Pitting Corrosion of 20Cr13 Steel

2008 ◽  
Vol 38 ◽  
pp. 238-247
Author(s):  
A.D. Davydov ◽  
V.S. Shaldaev
Keyword(s):  
Pitting Corrosion ◽  
Open Circuit Potential ◽  
Corrosion Potential ◽  
Ph Value ◽  
Open Circuit ◽  
Effect Of Temperature ◽  
Pitting Potential ◽  
Free Corrosion Potential ◽  
External Power Source ◽  
Corrosion Of Steel

The initiation and development of pitting corrosion of steel 20Cr13 in the NaCl solutions with various concentrations, temperatures, and pH values are studied under the potentiostatic conditions and at the free-corrosion potential. The pitting and repassivation potentials are determined using the method of cycling voltammetry. In spite of the fact that thus determined pitting potential is more positive than the corrosion potential (the open-circuit potential Eo.c.), the long-term experiments, which were performed at the free-corrosion potential, showed that pitting corrosion takes place without imposing a potential using an external power source. It is concluded that the probability of pitting corrosion of steel should be determined by comparing the corrosion potential (the open-circuit potential) with the repassivation potential Erp. Steel 20Cr13 is prone to the pitting corrosion, because Erp is more negative than Eo.c.. In the potentiostatic experiments, the variation of the depth and diameter of pits and their number with the time and the effect of temperature and electrode rotation on the pit propagation are studied. The results, which were obtained at the free-corrosion potential, are much less reproducible. In this case, in contrast to the potentiostatic conditions, the pit depth increased only slightly and the pit width increased to a larger extent. The effect of concentration, pH value, and temperature of NaCl solutions on the pit propagation is considered. It is concluded that the data on the development of pitting corrosion under the potentiostatic conditions can be hardly extended to the conditions of free corrosion potential.

Effects of high temperature on the growth and composition of sugarcane internodes

2006 ◽  
Vol 57 (10) ◽  
pp. 1087 ◽  
Author(s):  
G. D. Bonnett ◽  
M. L. Hewitt ◽  
D. Glassop
Keyword(s):  
High Temperature ◽  
Soluble Sugars ◽  
Dry Mass ◽  
Temperature Treatment ◽  
Sucrose Content ◽  
Insoluble Fibre ◽  
Higher Temperature ◽  
Lower Temperature ◽  
Leaf Appearance ◽  
Possible Cause

Sugarcane grown in the Ord River district of Western Australia has lower sucrose content than expected from earlier trials and experience in other irrigated districts. High temperatures have been hypothesised as a possible cause. The effects of high temperature (above 32°C) on growth and carbon partitioning were investigated. A temperature regime of (25–38°C) was compared with (23–33°C). In one experiment, 7-month-old plants of cvv. Q117 and Q158 were subjected to the treatments for 2 months. In another experiment, the plants were allowed to regrow (ratoon) for 6 months. In both experiments, the higher temperature resulted in more, shorter internodes and higher moisture content. Most internodes from plants in the higher temperature treatment had lower sucrose content than internodes from the lower temperature. On a dry mass basis the internodes from the plants in the higher temperature had proportionately more fibre and hexoses but lower sucrose. Combined with an increased number of nodes in a stem of similar or shorter length this would result in higher stalk fibre and lower sucrose content. The data provided evidence that sugarcane partitions less carbon to stored sucrose when grown under high compared with low temperatures. The two cultivars partitioned carbon between soluble (sugars) and insoluble (fibre) fractions to different degrees. These experiments also indicate that the current models describing leaf appearance and perhaps sugarcane growth at temperatures above 32°C, in general, need revision.

Study of mechanical properties and subsurface damage of quartz glass at high temperature based on MD simulation

2019 ◽  
Vol 04 (02) ◽  
pp. 1950003 ◽  
Author(s):  
Xiaoguang Guo ◽  
Chong Chen ◽  
Renke Kang ◽  
Zhuji Jin
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
High Temperature ◽  
Quartz Glass ◽  
Subsurface Damage ◽  
Simulation Based ◽  
Glass Model ◽  
Crystal Model ◽  
Higher Temperature ◽  
Lower Temperature

The mechanical properties (hardness, elastic modulus) and subsurface damage of quartz glass at high temperature are studied by nanoindentation simulation based on molecular dynamics (MD). By heating the quartz crystal model to 3000[Formula: see text]K and annealing to 300[Formula: see text]K twice, the quartz glass model is prepared. According to the nanoindentation simulation results, the hardness of quartz glass decreases by 53.6% and the elastic modulus increases by 10.9% at 1500[Formula: see text]K compared to those at 300[Formula: see text]K. When the temperature rises from 300[Formula: see text]K to 1500[Formula: see text]K, the critical grinding depth of quartz glass increases from nanoscale to micron-scale. The investigation of subsurface damage shows that the damaged layer thickness decreases slightly with the increase of temperature. The damaged layer extends downward under the indenter at lower temperature and extends along the indenter at higher temperature.

Crystallisation of amorphous Mg-Fe silicates produced from microwave-dried sol-gels

2019 ◽  
Vol 15 (S350) ◽  
pp. 408-409
Author(s):  
Stephen P. Thompson ◽  
Anna Herlihy ◽  
Claire A. Murray ◽  
Annabelle R. Baker ◽  
Sarah J. Day
Keyword(s):  
High Temperature ◽  
Powder Diffraction ◽  
Protoplanetary Disks ◽  
Activation Energies ◽  
X Ray ◽  
Higher Temperature ◽  
Lower Temperature

AbstractAmorphous Mg-Fe silicates are produced from microwave-dried sol-gels and their thermal crystallisation is studied via in situ synchrotron X-ray powder diffraction. Mg-pyroxene crystallised to forsterite, enstatite and cristobalite. The inclusion of 10% Fe formed only forsterite at much higher temperature, while pure Mg-olivine crystallised at a lower temperature than Mg-pyroxene. Cristobalite is observed as a high-temperature crystallite in the pure-Mg compositions. Crystallisation activation energies are derived and discussed in relation to protoplanetary disks.

scholarly journals Effect of high temperature stress on the performance of twelve sweet pepper genotypes

1970 ◽  
Vol 35 (3) ◽  
pp. 525-534 ◽  
Author(s):  
SR Saha ◽  
MM Hossain ◽  
MM Rahman ◽  
CG Kuo ◽  
S Abdullah
Keyword(s):  
High Temperature ◽  
Temperature Stress ◽  
Reproductive Behaviour ◽  
Sweet Pepper ◽  
High Temperature Stress ◽  
Fruit Weight ◽  
Temperature Regimes ◽  
Higher Temperature ◽  
Heat Tolerant ◽  
Lower Temperature

A study on heat tolerance in sweet pepper was conducted at the Asian Vegetable Research and Development Centre (AVRDC), Taiwan from December 1999 to May 2000. Experiments were carried out to investigate the influence of 29/23°C and 24/18°C stress on 12 sweet pepper genotypes on growth, development, reproductive behaviour and yield potentialities and to verify the results of the phytotron study. Performance of 12 sweet pepper genotypes was evaluated under two different temperature regimes of 24/18° C and 29/23° C in the phytotron. Plant height was found higher at 29/23° C compared to 24/18° C. High temperature reduced percent fruit set as well as size of fruits. Individual fruit weight was higher (7.44-125.00 g) when grown at 24/18°C and lower (5.35-103.80 g) at 29/23°C. Out of 12 genotypes, SP00l, SP002, SP004, and SP012 performed poor in respect of per plant yield at higher temperature compared to the lower temperature. So, these four genotypes were considered to be heat sensitive than the others. Leaf proline content of the sensitive genotypes decreased under the high temperature conditions and the heat tolerant lines produced higher amount of proline indicating the role of proline in expressing the heat tolerant capability of sweet pepper genotypes concerned. Keywords: High temperature stress; performance; sweet pepper. DOI: 10.3329/bjar.v35i3.6459Bangladesh J. Agril. Res. 35(3) : 525-534

Effects of filtration temperature, humic acid level and alum dose on cryptosporidium sized particle breakthrough

2006 ◽  
Vol 54 (11-12) ◽  
pp. 353-361
Author(s):  
G.R. Xu ◽  
C.S.B. Fitzpatrick ◽  
L.Y. Deng
Keyword(s):  
High Temperature ◽  
Humic Acid ◽  
Acid Level ◽  
Low Dose ◽  
Optimal Dose ◽  
Influence Of Temperature ◽  
Ζ Potential ◽  
Before And After ◽  
Higher Temperature ◽  
Lower Temperature

Recent Cryptosporidium outbreaks have highlighted concerns about filter efficiency and especially particle breakthrough. Understanding the causes of breakthrough is essential, as the parasite cannot be destroyed by conventional disinfection with chlorine. Particle breakthrough depends on many factors. This research aims to investigate the influence of temperature, humic acid (HA) level and chemical dosing on particle breakthrough in filtration. A series of temperatures were set at 5 °C, 15 °C and 25 °C; humic acid level was 5 mg L−1. Each was combined with a series of Al doses. A laser particle counter was used to assess the particle breakthrough online. Turbidity, ζ potential, and UV254 absorption were measured before and after filtration. The results showed that particle breakthrough was influenced significantly by temperature, humic acid and dosing. Particle breakthrough occurred earlier at lower temperature, while at higher temperature it was reduced at the same coagulant dose. With coagulants, even at low dose, particle breakthrough was significantly reduced. With HA 5 mg L−1, particle breakthrough was earlier and the amount was much larger than without HA even at high temperature. There was an optimal dose in filtration and it was well correlated with ζ potential.

326. The effect of temperature of pre-heating, of clarification and of bacteriological quality of the raw milk on the keeping properties of whole-milk powder dried by the Kestner Spray Process

1945 ◽  
Vol 14 (1-2) ◽  
pp. 116-159 ◽  
Author(s):  
A. T. K. Mattick ◽  
Edith R. Hiscox ◽  
E. L. Crossley ◽  
C. H. Lea ◽  
J. D. Findlay ◽  
...  
Keyword(s):  
Heating Temperature ◽  
Milk Powder ◽  
Raw Milk ◽  
Effect Of Temperature ◽  
Milk Supply ◽  
Spray Process ◽  
Bacteriological Quality ◽  
Higher Temperature ◽  
Lower Temperature

(1) Increasing the pre-heating temperature of the milk from 165 to 190° F. before spray-drying greatly improved the resistance of the powder to the development of tallowy ‘off’-flavours on storage. From the results of accelerated tests at 47 and 37° C. a storage life (in air) of the order of 2 years could safely be predicted for the powders from milk pre-heated at the higher temperature. Confirmation has now been obtained by storage of the powders for 2½ years at 15° C. and at room temperature.(2) Improvement in the bacteriological quality of the milk supply, and more careful control during its passage through the plant, produced some improvement in the keeping properties of powders prepared from milk pre-heated at the lower temperature, but had relatively little effect on the keeping properties of the powder when the higher preheating temperature was used.(3) The shapes of the deterioration curves for the various powders showed that the effect of the higher pre-heating temperature and of improvement in the milk supply was to extend the induction period which precedes rapid deterioration. The protective effect of both factors was greater when measured at the ‘slightly tallowy’ or ‘fairly good’ stage than when comparison was made at a more advanced stage of decomposition.

scholarly journals Back-reacted saponite in Jurassic mudstones and limestones intruded by a Tertiary sill, Isle of Skye

Clay Minerals ◽  
2005 ◽  
Vol 40 (3) ◽  
pp. 263-282 ◽  
Author(s):  
S. J. Kemp ◽  
C. A. Rochelle ◽  
R. J. Merriman
Keyword(s):  
High Temperature ◽  
Thermal Effects ◽  
Mineral Assemblage ◽  
Fracture System ◽  
Detailed Understanding ◽  
Higher Temperature ◽  
Lower Temperature ◽  
Host Rocks ◽  
Grossular Garnet ◽  
Isle Of Skye

AbstractThe Lòn Ostatoin stream section, Trotternish Peninsula, Isle of Skye, exposes a sequence of Middle Jurassic mudstones and limestones which have been locally metasomatized by a transgressive sill of Tertiary age. Limestones in the sequence, including some previously reported as bentonite, have been altered to an unusual assemblage of grossular garnet and saponite clay. The mudstones also contain large proportions of saponite together with pyroxene and zeolites. Saponite also occurs within the basalt intrusion. Grossular and pyroxene represent artifacts of relatively high-temperature assemblages that formed during an early phase of alteration. As the intrusion and adjacent altered country rocks cooled, lower-temperature fluids flowed through a late set of contraction (micro)fractures. Back-reacted saponite, analcime and clinoptilolite were formed, possibly as alteration products of the unstable higher-temperature minerals. The lower-temperature mineral assemblage eventually sealed the late fracture system.This paper highlights an important concept for the study of analogue sites used to investigate thermal effects on engineered liners or barrier host rocks for the landfill and radioactive-waste industries. This is that the original thermally altered mineral assemblage may be overprinted by later, lower-temperature back-reactions. A detailed understanding of both processes is necessary in order to construct a sensible model for the thermal and mineralogical evolution of the site.

scholarly journals Corrosion Behavior of Some Timonb Alloys in Ringer Solution

2020 ◽  
Vol 71 (7) ◽  
pp. 187-196
Author(s):  
Maria Magdalena Pricopi ◽  
Romeu Chelariu ◽  
Nicolae Apostolescu ◽  
Doina-Margareta Gordin ◽  
Daniel Sutiman ◽  
...  
Keyword(s):  
Corrosion Behavior ◽  
Immersion Time ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Ph Value ◽  
Electrochemical Techniques ◽  
Ringer Solution ◽  
Open Circuit ◽  
Chemical Compositions ◽  
Solution Ph

The aim of this study was to investigate the influence of different process parameters as chemical composition, the pH value and immersion time on the corrosion of the some TiMoNb alloys, using different electrochemical techniques such as: cyclic voltammetry, open circuit potential (OCP) measurement, polarization curves and electrochemical impedance spectroscopy (EIS). The alloys were analyzed in the natural pH of the Ringer solution, but also with an acidic modification of the solution (ph = 4) and a basic modification (ph = 8). The more acidic values of pH, the more evident are differences between corrosion behavior of titanium-based alloys depending on their chemical compositions and immersion times.

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