•Unilateral sample preparation and control of oxygen did not reduce scatter.•Oxide deposition was observed in some facilities while others reported oxide loss.•Interlaboratory statistics indicate ...between-laboratory differences were significant.•Temperature distributions within autoclaves proposed as one cause of scatter.
Supercritical water-cooled reactor candidate materials are typically corrosion-resistant alloys whose mass changes in supercritical water fluctuate around zero. A previous interlaboratory corrosion experiment exercise revealed large scatter in mass change results between laboratories. Here, we reduced systemic differences between laboratories by unilateral preparation of coupons and unilateral chemical cleaning. Type 310S stainless steel and Alloy 800HT test coupons were exposed for 1000 h to 550 °C, 25 MPa, deaerated water. Average mass loss for 310S and 800HT was 38 ± 26 and 51 ± 31 mg/dm2, respectively. Differences in mass transfer, galvanic and local corrosion, and average coupon temperature may explain the poor reproducibility.
•Electrochemical impedance of stainless steel was measured in supercritical water.•High frequency impedance depends on water electric conductivity and permittivity.•Corrosion parameters can be ...obtained from low frequency impedance data.•Local increase in corrosion rate around the critical temperature was confirmed.•Electrochemical data agreed well with weight difference data from literature.
The traditional method of corrosion studies of structural materials exposed to water at high pressures and temperatures is ex-situ weight gain/loss estimation and analyses of the oxide scales. In this work, in-situ electrochemical impedance spectroscopy (EIS) is applied to study behaviour of 316 L stainless steel exposed to sub-critical and super-critical water (SCW) with the aim to investigate the effect of temperature, in particular close to the critical point of water. As the second objective, the effect of exposure time during the long-term exposure at 500 °C was investigated. Impedance data were analyzed and discussed, based on changes in the physical and chemical properties of water. Instantaneous corrosion rate data, estimated from impedance data, were converted in weight differences and compared with the literature data available for 316 L steel corrosion in SCW. The good agreement obtained supports applicability of in-situ EIS for corrosion studies in super-critical range.
The paper deals with the burnt lime utilization as a source of calcium ions participated during hydration process of ultra-high performance cementitious composites. These type of ultra-high ...performance cementitious composites are based on the high content of silica fume that together with calcium ions form the binder phase. In the case of ordinary Portland cement, the hydration during induction period supposed to be too slow for dissolution of required amount of calcium ions necessary for the pozzolanic reaction of presented silica fume. The low addition of the lime should be a sufficient calcium source that allow the starting of the pozzolanic reaction before the acceleration period occurs. The calcium ions content from the beginning of the reaction was controlled by an addition of soft-burnt and dead-burnt lime. Its influence was studied in terms of hydration process by isothermal calorimetry. Based on the experimental data, the hydration reaction mechanism was proposed.
This paper deals with possibilities of application brick-grind-dust which is a secondary product from manufacturing of grinded bricks. This product is usually partially returned to brick ...manufacturing or buried on a land field site. The basic idea of using this material in systems based on cement comes from their mineral composition, origin and particle size. These materials are potentially pozzolan active, which is interesting for use in hydraulic binders. Also red colour of brick dust can be interesting for visual application. First physical and chemical properties of brick-grind-dust was studied, then binders based on the material and Portland cement were prepared. Mechanical properties of prepared binders were studied over time. Hydration of the selected binders was analysed with isothermal calorimetry.
Corrosion exposure of MA956 and PM2000 in 650°C SCW was performed.Oxide layer thickness of exposed MA 956 specimens ranged from 2μm to 4.5μm.8μm thick oxide layer was observed for PM 2000 ...specimens.Sites of nodular corrosion was observed along the surfaces of the ⿿ground⿿ specimens.
This paper summarizes the results of supercritical water corrosion studies of two ferritic oxide dispersion strengthen (ODS) steels MA956 and PM2000 at the temperature of the upper limit of potential peak cladding temperature under normal operation, according to the conceptual design being developed in the EU. As the high temperature and pressure above the thermodynamic critical point of water result in higher oxidation rate for conventional austenitic alloys than observed in sub-critical light water reactor (LWR) conditions, ensuring adequate corrosion resistance is critical for thin-wall components like fuel cladding. This study concentrated on the investigation of two effects, surface finish and orientation of the cuts. Two different surface treated coupons were prepared in order to study the effect of cold work in sample surface on corrosion resistance. Samples were exposed in supercritical water at 650°C and 25MPa, for up to 1800h. The corrosion rate was evaluated by measuring the weight change of the samples and by cross-section examinations. The microstructure of the oxide layers was analyzed using a scanning electron microscope (SEM) in conjunction with energy dispersive spectroscopy (EDS) and X-ray diffraction analysis (XRD). Weight gain results of both ODS steels proved a good resistance to general corrosion. Nevertheless the cross-sectional SEM study showed signs of nodular corrosion, observed mostly on the ground specimens after long exposure times.
This work deals with the reactivity of XRD amorphous delaminated and dehydroxylated talc phase (meta-talc), in alkali medium. Talc ore Luzenac H70 was treated in a stirred ball mill (attritor) for ...30; 60 and 90 min with subsequent thermal treatment at 700°C; 750°C and 800°C. Reactivity of mechanochemically and thermally treated talc ore in NaOH solution was studied using isothermal calorimetry. An influence of material crystallinity and amount of water coordinated in material structure after milling on its reactivity in alkali medium was studied.
A repeated soil survey (1995 and 2006) on 66 ICP Forests pair plots in the Czech Republic revealed a significant relationship between modeled nitrogen deposition and nitrogen concentration in the ...soil. Nitrogen deposition was modeled for the years 1995, 2004 and 2006. We found a more significant relationship between deposition data in 2004 and soil data in 2006 than between deposition and soil data from the same year 2006. Concentration of total nitrogen in forest soil increased from 1995 to 2006. Forest soil showed effects of increased nitrogen input from the humus layer to around 20 cm depth of mineral soil. The occurrence and cover of nitrophilous species in the herb layer increased from 1995 to 2006 in 25% of the analyzed plots, which corresponds to the nitrogen increase in forest soil. The results suggest that nitrogen deposition still represents a threat for Czech forest ecosystems.
The introduced case report explains the atypical periprocedural myocardial infarction following the surgical myocardial revascularization. 60-year-old man has undergone the coronary bypass surgery ...with arterial graft of left mammary artery (LIMA) to left anterior descending artery (LAD) and venous graft to posterior interventricular branch of right coronary artery. Early in the post-surgery period a perioperative myocardial infarction (PMI) developed, with laboratory correlation of cardio-specific enzymes elevation and ECG changes in terms of ischaemia in the diaphragmatic region. Echocardiography showed akinesia of the apex, apical septal and apical inferior segments accompanied by the decrease in ejection fraction (EF) of the left ventricle. Selective coronarography was performed showed the proper functionality of arterial as well as venous graft, however, examination also showed severe stenosis of the left subclavian artery (LSA) with limitation of flow through LIMA. Percutaneous angioplasty of the LSA and implantation of the stent was performed in the emergency regime with optimal results. In severe stenosis of the LSA, the progression of the so-called coronary-subclavial steal syndrome is developed, with retrograde flow into LIMA resulting in ischaemia of the supplied part of the myocardium. Nevertheless, steal phenomenon with reverse flow in LIMA is not an absolute requisite for development of the myocardial ischaemia. In some cases stenosis of the LSA manifests in similar fashion as the proximal stenosis of LIMA, which was the case of with the patient shown here.
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