Corrosion Tests In Water Research Articles

Corrosion and stress corrosion behavior of CuCrZr alloy in high temperature pure water environment relevant to Japan's DEMO divertor

CuCrZr alloy is one of leading candidate of the cooling system of the Japan's DEMO divertor. Proposals of operating conditions resembles in-service light water reactors hence underlines the importance of water chemistry. The latter significantly affects corrosion behavior. To understand CuCrZr alloy's corrosion behavior, several 500-hr static water corrosion tests with various water conductivity and water chemistries (including dissolved oxygen 100ppb respectively dissolved hydrogen 1600 ppb) at 230 °C pure water were conducted. Additional creviced bent beam (CBB) tests in degassed water and in water with dissolved hydrogen 1600 ppb at 230 °C up to 1000 h were also conducted to investigate stress corrosion behavior. Results showed that the weight loss of coupons tested in oxygen dissolved water was tenfold than that of in degassed water; and the loss in degassed water is twenty times higher than that of in hydrogen dissolved water. Presence of pure copper precipitates on coupons tested in hydrogen dissolved water suggests the occurrence of hydrogen reduction. In degassed water, the weight loss at high water conductivity (0.3 μS/cm) was close to that of low water conductivity (≦0.1 μS/cm), suggesting that the effect brought by water conductivity was smaller than the effect brought by different water chemistries. All CBB test coupons show no cracks. Relatively deeper metal dissolution induced etching at grain boundaries were observed comparing with those coupons from static water corrosion tests. Combined factors of tensile stress and metal dissolution lead to a speculation that stress corrosion cracking might happen under other aggressive environments or testing methods.

Water-Immersion Stability of Self-Compacting Potassium Magnesium Phosphate Cement Paste

For the repair of narrow cracks in concrete, the potassium magnesium phosphate cement (MKPC)-based material paste should have high fluidity and self-compacting ability, making it convenient for pouring and compacting. A self-compacting MKPC paste that meets the index requirements recommended by the European Federation of National Associations Representing for Concrete (EFNAFC) was prepared by increasing the water-cement ratio and adding water glass and fly ash (FA). Specimens of self-compacting MKPC paste were subjected to long-term water corrosion tests, which found that those high-fluidity MKPC paste specimens (reference sample M0) that were produced with only an increased water-cement ratio lost 15-30% of their strength. The residual ratio of folding to compression was 84.6%, and the volume expansion rate was 7.78 × 10-4 after immersion in water for 560 days. The strength residual rate of MKPC slurry (M1) modified by sodium silicate and fly ash is over 90% after 560 days of immersion in water, and the residual rate of flexural-compressive ratio is 101.3%, which meets the requirements of hydraulic cement-based materials. The volume expansion rate of M1 is 5.19 × 10-4, which is 67% of the reference sample M0 with the same water immersion age.

Corrosion tests in water of fuel elements irradiated in the world’s first NPP reactor

Spent nuclear fuel (SNF) storage in reactor spent fuel pools (SFP) is one of the crucial stages of SNF management technology: it requires special measures to ensure nuclear and radiation safety. During long-term storage in water-filled SFPs, leak-tight canisters in which SFAs are usually placed can become unsealed, which will result in the development of corrosion processes in the fuel element (FE) claddings. We studied fragments of spent fuel elements of the AM reactor of the World’s First NPP during their long exposure in the aqueous medium. The aim of the study was to obtain experimental data on the corrosion changes in the FE claddings and fuel composition during storage as well as on the release of radioactive fission products from them. For the study, a laboratory facility for exposing fuel elements in the water was developed and experimental fragments of fuel elements were made. The study was carried out in the hot chamber of the SSC RF-IPPE. The change in the activity of the water was estimated by the γ-dose rate from the selected water sample. The diameter measurements and metallographic studies were carried out in various sections of FE fragments. Corrosion tests were carried out on fragments of spent fuel elements of the AM reactor of the World’s First NPP that were stored for a long time (more than 50 years – FEs with U-Mo fuel and ~ 20 years – FEs with UO2 fuel) using standard technology – first in SFP canisters filled with water and then in dry canisters in the air. Placing the fuel elements in the water did not lead to through damage to the FE claddings and a significant change in the size (diameter) of the outer cladding. Metallographic studies of the FE fragments after the corrosion tests showed the presence of intergranular and local frontal corrosion on the surface of the claddings, the depth of which exceeded the depth of the cladding corrosion defects before testing. The rate of radionuclide release from the fuel composition was estimated by the γ-dose rate of water samples taken from the glasses with FE fragments. Throughout the test period, the dose rate of water samples from the glasses with defect-free FEs remained constant. The dose rate from water samples taken from the glasses with the FE fragments with an artificial defect grew during storage.

Коррозионные испытания в водной среде твэлов, облученных в реакторе первой в мире АЭС

Коррозионные испытания в водной среде твэлов, облученных в реакторе первой в мире АЭС

The corrosion behaviour of alloy 690 tube in simulated PWR secondary water with the effect of solid diffusing hydrogen

High-temperature water corrosion tests were performed to investigate the corrosion behaviors of Alloy 690 TT in simulated PWR secondary water with gaseous hydrogen permeation condition. Double-layer oxide films formed on hydrogen-free and hydrogen-permeating specimens. The thickness of a Cr-rich inner oxide film on the hydrogen-free specimens has no obvious difference from the hydrogen-permeating ones. For hydrogen-free specimens, the outer oxide films were Fe and Ni enriched spinel-type oxide particles. For hydrogen-permeating specimens, outer oxide films were sheet-like or needle-like Cr-rich chromia-type oxides. In summary, the solid diffusing hydrogen affected the morphology and composition of outer oxides.

Discussion on the relationship between iron content and corrosion rate in production fluid of oil wells

To provide an economical and practical technique for the application of on-line corrosion monitoring technology in oil production system, in this paper, the iron content was measured by a water quality multi-parameter tester and corrosion rate was determined by the weight loss method. Then, the quantitative relationship between the iron ion and corrosion rate could be found. On this foundation, in order to correctly describe the corrosion in the wellbore of oil wells, according to SY/T0026-1999 water corrosion test method standards, a mathematical relational expression between iron ion content and corrosion rate in oil wells production fluid was established. In order to verify the reliability of relational expression, the iron content in the produced fluid of 17 wells corrosion conditions before and after adding medicine were measured on the spot. Then, the relational expression entered the field application. The results show that there was the positive correlation between the iron ion and corrosion rate. The error of the calculated corrosion rate of 17 wells in the field was less than 26% compared with the measured corrosion rate. The mathematical relational expression had good effect in J45-62 well. It could reflect the corrosion trend of well bore. Thus, through the internet+ technology, the on-line monitoring system for remote corrosion could be established, and corrosion trend of wellbore pipelines could be predicted with the help of nerve net algorithm.

High-Temperature Corrosion Testing of Uranium Silicide Surrogates

The corrosion resistance of cerium silicide, a surrogate of uranium silicide, is investigated to gain insight into the reaction of uranium silicide with water. As-received and proton-irradiated Ce3Si2, CeSi2, and CeSi1.x monolithic pellets are subjected to corrosion tests in water at 300°C and 9 MPa for up to 48 h. Results show that an oxide layer composed of Ce4.67 (SiO4)3O forms on the surface of all samples, and it grows thicker with extended exposure times. Irradiated samples corrode to a greater extent than their unirradiated counterparts, which is mainly a result of the existing post-irradiation cerium oxide and the presence of ion-induced defects. Most of the Ce3Si2 samples crack (as-received) or fracture (ion-irradiated) during testing, which is due to the brittleness of the samples and oxide erosion/spallation that occur during testing.

Deuterium diffusion in LiOH–water-corroded oxide layer of zirconium alloys

In order to clarify the hydrogen diffusion mechanism in the oxide layer of zirconium alloys, in situ hydrogen isotope diffusion in the oxide layer has been examined. The zirconium alloys used were Zircaloy-2, GNF-Ziron (Zircaloy-2 type alloy with high iron content) and VB (zirconium-based alloy with high iron and chromium contents). They were corroded in 1 or 0.1M LiOH-containing water at 563K, producing oxide layers of 1.1–2.1μm in thickness. The diffusion experiments were carried out in the temperature range from 488 to 633K by using a combined technique of deuterium plasma exposure and nuclear reaction analysis for D (3He,p)4He reaction. From the transient deuterium profiles in the oxide layers, it was concluded the LiOH–water-corroded oxides had a single-layer structure, which was in contrast to the double-layer structure previously observed in steam-corroded oxide layers. The diffusion coefficients in the 1M LiOH–water-corroded oxides evaluated from the deuterium profiles were smaller in the order of Zircaloy-2>GNF-Ziron>VB at 573K. For the 0.1M LiOH–water-corroded oxide of GNF-Ziron, the diffusivity was lower than that of the 1M LiOH–water-corroded oxide by a factor of 1/4. The present diffusion coefficients of the 1M LiOH–water-corroded oxides of GNF-Ziron and VB were approximately 7 times larger than the previous data of the corresponding steam-corroded oxides. The deuterium diffusion properties in the oxides of the three alloys obtained in the in situ experiment were roughly consistent with their hydrogen absorption performances in the LiOH–water-corrosion tests, as well as in the previous steam corrosion tests.

General corrosion properties of modified PNC1520 austenitic stainless steel in supercritical water as a fuel cladding candidate material for supercritical water reactor

The Super-Critical Water-cooled Reactor (SCWR) has been designed and investigated because of its high thermal efficiency and plant simplification. There are some advantages including the use of a single phase coolant with high enthalpy but there are numerous potential problems, particularly with materials. As the operating temperature of supercritical water reactor will be between 280°C and 620°C with a pressure of 25MPa, the selection of materials is difficult and important. Austenitic stainless steels were selected for possible use in supercritical water systems because of their corrosion resistance and radiation resistance. The PNC1520 austenitic stainless steel developed by Japan Atomic Energy Agency (JAEA) as a nuclear fuel cladding material for a Na-cooled fast breeder reactor. The corrosion data of PNC1520 in supercritical water (SCW) is required but does not exist. The purpose of the present study is to research the corrosion properties for PNC1520 austenitic stainless steel in supercritical water. The supercritical water corrosion test was performed for the standard PNC1520 (1520S) and the Ti-additional type of PNC1520 (1520Ti) by using a supercritical water autoclave. Corrosion tests on the austenitic 1520S and 1520Ti steels in supercritical water were performed at 400, 500 and 600°C with exposures up to 1000h. The amount of weight gain, weight loss and weight of scale were evaluated after the corrosion test in supercritical water for both austenitic steels. After 1000h corrosion test performed, the weight gains of both austenitic stainless steels were less than 2 g/m2 at 400°C and 500°C . But both weight gain and weight loss of 1520Ti were larger than those of 1520S at 600°C . By increasing the temperature to 600°C, the surface of 1520Ti was covered with magnetite formed in supercritical water and dissolution of the steel alloying elements has been observed. In view of corrosion, 1520S may have larger possibility than 1520Ti to adopt a supercritical water reactor core fuel cladding.

The protective properties of ultra-thin diamond like carbon films for high density magnetic storage devices

With the increase of magnetic storage density, the thickness of the protective diamond like carbon (DLC) film on the surfaces of head and disk is required as thin as possible. In this paper, the structure, mechanical properties and corrosion and oxidation resistance of ultra-thin DLC films are investigated. The ultra-thin DLC films were deposited by using filtered cathodic vacuum arc (FCVA) technique. The exact thickness of the ultra-thin DLC film was determined by high resolution transmission electron microscope (HRTEM). Raman analysis indicates that the ultra-thin DLC film presents ta-C structure with high sp 3 fraction. In the wear test, a diamond tip was used to simulate a single-asperity contact with the film surface and the wear marks were produced on the film surface. The wear depths decrease with film thickness increasing. If the film thickness was 1.4 nm or above, the wear depth was much lower than that of Si substrate. This indicates that the ultra-thin DLC film with thickness of 1.4 nm shows excellent wear resistance. Corrosion tests in water and oxidation tests in air were carried out to investigate the diffusion barrier effect of the ultra-thin DLC films. The results show that the DLC film with thickness of 1.4 nm provides adequate coverage on the substrate and has good corrosion and oxidation resistance.

The Effect of Hydrogen on the Transition Behavior of the Corrosion Rate of Zirconium Alloys

Abstract Three zirconium alloys (Zry-4, Zry-2, and NDA) were corrosion tested at 633 K in pure water and in mixed gas of Ar and oxygen. In both environments, their corrosion rate showed cyclic changes. The time and the weight gain at the transition point changed with their corrosion resistance. In the pure water corrosion test, one test cycle was 600 h, and the cumulative total test duration was as much as 7200 h. After each test cycle, the weight changes and the hydrogen contents were analyzed. The hydrogen pick-up ratio was calculated for each test cycle based on the weight change and the increase of the hydrogen content. The calculated hydrogen pick-up ratios were not constant. They showed periodic changes. In the pre-transition region, the corrosion rate showed a gradual decrease; however, the calculated hydrogen pick-up rate gradually increased. After the transition, in contrast to the increase in the corrosion rate, the calculated hydrogen pick-up rate decreased. The changes of the corrosion rate and the calculated hydrogen pick-up rate for the test interval exhibited an inverse relationship. Transmission electron microscopy (TEM), scanning TEM, energy dispersive x-ray (EDX) spectroscopy, and electron diffraction (ED) pattern analysis of the oxide/metal interface showed the existence of an interface layer that consists of distorted ZrO2 and a sub-oxide. Before the transition, the interface layer was clearly observed. On the other hand, the interface layer disappeared after the transition. The cyclic changes in the corrosion rate were closely related to the interface barrier layer at the oxide/metal interface. The interface layer suppresses the corrosion rate, and the degradation of its barrier property increases the corrosion rate. By comparing the morphology of the oxide/metal interface between the water corrosion samples and the mixed gas oxidation samples, it can be seen that the generated hydrogen in the oxide may have two opposite effects. One is to stabilize the interface layer and to suppress the transport of the oxygen ion, and the other is to degrade the interface layer at the transition and accelerate the generation of the uniform oxide. The effect of the chemical composition on the properties of the oxide-metal interface and the mechanism of the corrosion transition will be discussed.

Corrosion resistance of Zn–Al co-cementation coatings on carbon steels

Zn–Al co-cementation coatings on carbon steels have been obtained by pack cementation method. The coatings possess a two-layered structure. The outer layer is composed mainly of Fe 2Al 5 and FeAl intermetallics with a small amount of Zn and the inner layer consists of Zn, Fe and a small amount of Al. The corrosion resistance of the Zn–Al co-cementation coatings was studied with rotary corrosion test in water and NaCl and H 2S containing solutions. High-temperature oxidation and sulphidation were carried out in air and H 2S containing atmosphere at 500 °C. The experimental results were compared with the coatings produced by Zn sherardizing and aluminizing, showing that the Zn–Al co-cementation coatings have much better corrosion resistance in both aqueous solutions and high-temperature environments.

Zirconium oxide film formation on zircaloy by water corrosion

The objective of this work is to study the morphological, micro-chemical and micro-mechanical characteristics of the thick zirconium oxide layer formed on a zircaloy-4 clad after a standard water corrosion test (ASTM G2-67). The oxidized samples were analyzed by Raman and Auger spectroscopy, SEM–EDS, XRD and the mechanical properties of the oxide film were evaluated using the Vickers microindentation method. The results reveal the formation of a textured oxide layer constituted of m-ZrO2 crystals oriented primarily in the direction perpendicular to the (002) crystallographic plane. In addition, a not previously reported thin zirconium carbide film on the top surface of the oxide layer was detected by SEM–EDS, XRD and Auger spectroscopy.

Reaction sintered glass: a durable matrix for spinel-forming nuclear waste compositions

Glass formation by reaction sintering under isostatic pressure is an innovative process to vitrify refractory-rich high-level radioactive waste. We used a typical defense waste composition, containing spinel-forming components such as ∼4 wt% of Cr 2O 3, ∼23 wt% Al 2O 3, ∼13 wt% Fe 2O 3, and ∼9 wt% UO 2, with CeO 2 simulating UO 2. Reaction sintered silicate glasses with waste loading up to 45 wt% were prepared within three hours, by hot pressing at 800°C. The glass former was amorphous silica. Simulated waste was added as calcined oxides. The reaction sintered glass samples were characterized using scanning and analytical electron microscopy. The results show that extensive reaction sintering took place and a continuous glass phase formed. Waste components such as Na 2O, CaO, MnO 2, and Fe 2O 3, dissolved completely in the continuous glass phase. Cr 2O 3, Al 2O 3, and CeO 2 were only partially dissolved due to incomplete dissolution (Al 2O 3) or super-saturation and reprecipitation (Cr 2O 3 and CeO 2). The precipitation mechanism is related to a time dependent alkali content in the developing glass phase. Short-term corrosion tests in water showed that the glasses are chemically more durable than melted nuclear waste glasses. Based on hydration energies calculations, the long-term chemical durability of our reaction sintered glasses is expected to be comparable to that of rhyolitic and tektite glasses.

Glass as a Waste Form for the Immobilization of Plutonium

AbstractSeveral alternatives for disposal of surplus plutonium are being considered. One method is incorporating Pu into glass and in this paper we discuss the development and corrosion behavior of an alkali-tin-silicate glass and update results in testing Pu doped Defense Waste Processing Facility (DWPF) reference glasses. The alkali-tin-silicate glass was engineered to accommodate a high Pu loading and to be durable under conditions likely to accelerate glass reaction. The glass dissolves about 7 wt% Pu together with the neutron absorber Gd, and under test conditions expected to accelerate the glass reaction with water, is resistant to corrosion. The Pu and the Gd are released from the glass at nearly the same rate in static corrosion tests in water, and are not segregated into surface alteration phases when the glass is reacted in water vapor. Similar results for the behavior of Pu and Gd are found for the DWPF reference glasses, although the long-term rate of reaction for the reference glasses is more rapid than for the alkalitin-silicate glass.

Surface interactions of fluorozirconate glass with low energy implanted Ar, N and O ions

Abstract A fluorozirconate glass was implanted with 15keV Ar, N and O ions. The implanted samples were characterized with optical spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy and water corrosion tests. The surface of Ar-ion implanted glass was depleted in fluorine and enriched with metallic zirconium precipitate. It was electrically conductive and susceptible to water corrosion. The N-ion implantation induced metallic zirconium and zirconium nitride formation as well as F depletion. The N-ion implanted surface was also conductive but strong against water corrosion. The oxyfluoride surface layer formed by O-ion implantation showed little influence on optical and electrical properties of the glass, and was highly durable against water corrosion. The significant dependence of the surface properties on implanted species is discussed with consideration of both physical andchemical features of incident ions.

Effect of pollutants on corrosion of copper alloys in sea water: Part 1: Ammonia and chlorine

AbstractThe results of sea water corrosion tests on five copper alloy heat exchanger materials are presented. The tests were undertaken to determine whether ammonia, commonly present as a pollutant in sea water, would adversely affect their corrosion behaviour. All five alloys proved more susceptible to crevice attack in the presence of ammonia when heat transfer conditions were additionally present. Crevice attack was suppressed by the addition of iron to the sea water. A second series of experiments, to examine the effect of the simultaneous presence of chlorine and ammonia in the sea water, showed that, while crevice attack was suppressed by the chlorine addition, two of the alloys became markedly more susceptible to impingement attack under these conditions. A discussion of service failures examined at BNF is presented, illustrating how the presence of ammonia can lead to failures and how such failures can be avoided.

Effect of pollutants on corrosion of copper alloys in sea water: Part 2: Sulphide and chlorine

AbstractThe results of sea water corrosion tests on five copper alloy heat exchanger materials are presented. The tests were undertaken to determine whether ammonia, commonly present as a pollutant in sea water, would adversely affect their corrosion behaviour. All five alloys proved more susceptible to crevice attack in the presence of ammonia when heat transfer conditions were additionally present. Crevice attack was suppressed by the addition of iron to the sea water. A second series of experiments, to examine the effect of the simultaneous presence of chlorine and ammonia in the sea water, showed that, while crevice attack was suppressed by the chlorine addition, two of the alloys became markedly more susceptible to impingement attack under these conditions. A discussion of service failures examined at BNF is presented, illustrating how the presence of ammonia can lead to failures and how such failures can be avoided.

Glass Formation in the Pseudobinary Metallic Selenide Systems MmSen‐Ge1.5As0.5Se3

The glass‐forming regions were investigated for pseudobinary systems of the composition XMmSen‐(1–X)Ge1.5As0.5Se3 (MmSen=PbSe, CdSe, BaSe, ZnSe, or La2Se3). Systems containing PbSe, CdSe, and BaSe contain substantial regions of glass formation, and differential scanning calorimetry, electron microscopy, and water corrosion tests were used to characterize these glasses. The glasses were generally phase‐separated, and the available data suggest that for PbSe melts the region of liquid‐liquid immiscibility spans almost the entire pseudobinary composition range. A few studies of glass formation were conducted for CdSe‐MmSen‐Ge1.5As0.5Se3 pseudoternary and MmSen‐GeSe2 binary melts.

Effect of barrier layer thickness on aqueous corrosion of aluminum

Barrier layer thickness of aluminum, which had been subjected to corrosion tests in water containing a few ppm of various reagents, was determined by the polarization method proposed by M. S. Hunter and P. Fowle.The thickness of barrier layer formed in the air decreased with increasing time of immersion in pure water up to 100hrs. The same behavior was also observed on aluminum tested in water containing any one of NaNO3, NaCl, NaOH, and HCl. While, in water containing any one of NaF, Na2SO4, Na2SiO3, H2SO4, and H3PO4, the thickness of the layer formed in the air once decreased at the initial stage of immersion, and then, began to increase.These results were compared with the corrosion rate of aluminum tested in the solutions mentioned above.It was concluded that there was inverse correlation between the corrosion rate of aluminum and the barrier layer thickness after the tests in the various testing solutions for 100hrs. Further studies shall be made in future to reveal the reason of specific effects of anion in testing solutions on the barrier layer thickness of aluminum which was immersed in the solutions.