Autoclave Tests Research Articles

The soundness of steel slag with different free CaO and MgO contents

In this study, five types of steel slags with different free CaO (f-CaO) and MgO contents were used as mineral admixtures to prepare concretes with W/B ratios of 0.5 and 0.35. The concretes were cured for 4years. Compressive strength and permeability to chloride ion were tested to reveal the influence of f-CaO and MgO on concrete soundness over 4years. An accelerated autoclave test was also adopted to investigate the influence of MgO on concrete soundness after 4years. The results show that the primary component that leads to the bad soundness of steel slag is f-CaO. Ca(OH)2 primarily with a bulk structure is produced by the hydration of f-CaO, which is different from the Ca(OH)2 produced by cement hydration. Steel slag with a 4.96% content of CaO presents bad soundness and leads to the soundness-induced failure of concretes at both high and low water-to-binder (W/B) ratios. When the content of f-CaO is within 2.09%, the steel slag presents satisfactory soundness. The results of the autoclave test show that when the content of MgO is within 7.68%, steel slag has no negative influences on the compressive strength of concrete.

Corrosion Analysis of Fuel Cell Metallic Materials at Elevated Temperature

Corrosion of fuel cell metallic materials cannot be prevented, but there are ways to mitigate it. Environment in the fuel cells can be extremely corrosive and materials for fuel cells construction can deteriorate very fast if appropriate design is not employed [1]. In this work, different metallic materials for fuel cell construction will be tested under various conditions. Especially, an autoclave test will be designed to established corrosion monitoring of these materials at high temperature. Moreover, we will construct an autoclave corrosion cell to monitor corrosion electrochemically by various electrochemical techniques. After the corrosion tests a surface analytical techniques will be employed to reveal the composition of the corroded material (if corrosion will occur) by employing atomic force microscopy, x-ray photoelectron spectroscopy, Auger electron spectroscopy, and secondary ion mass spectrometry. [1] Renato A. Antunes, Mara Cristina L. Oliveira, Gerhard Ett, Volkmar Ett, Corrosion of metal bipolar plates for PEM fuel cells: A review, International Journal of Hydrogen Energy, 35 (2010) 3632–3647. [2] Jixin Chen, Jingwei Hu, James R. Waldecker, Comprehensive Model for Carbon Corrosion during Fuel Cell Start-Up, Journal of The Electrochemical Society, 162 (2015) F878-F889.

Modification of Basic Oxygen Furnace Slag for Cement Manufacturing

The use of steelmaking slag without chemical modification presents a deleterious effect on cement mechanical properties, due to the expansion caused by the presence of free CaO and MgO in the slag. This work deals with the modification of one basic oxygen furnace (BOF) slag with the objective of making it an appropriate additive in blended cement formulations. Two different modified slags were produced in a pilot-scale metallurgical reactor by mixing additives into 300 kg of remelted BOF slag. The liquid slags were cooled under two conditions: naturally (inside the reactor) and in contact with stainless steel balls. Quantitative X-ray diffraction and energy-dispersive spectroscopy, as well as qualitative scanning electron microscopy and Raman spectroscopy analyses of slag samples, revealed the relationship among cooling conditions and crystalline phases. The modified slags had CaO/SiO2 between 1.8 and 2.0, which is lower than the 3.8 for steelmaking slag. This reduced basicity resulted in the presence of dicalcium silicates (C2S) in higher amounts than in the steelmaking slag. β-Ca2SiO4, α′-Ca2SiO4, bredigite, and RO (FeO–MgO–MnO–CaO solid solution) were detected as major crystalline phases by X-ray diffraction and Raman spectroscopy. Cement samples were produced by mixing 25 wt% of modified steelmaking slag with 75 wt% of ordinary Portland cement, resulting in expansion lower than 0.1% in the autoclave tests and compressive strength higher than 40 MPa after 28 days. Cement samples produced by adding modified slags presented expansions 5 times lower than that determined for cement samples produced by adding steelmaking slag without any modification. The process indicates potential to be applied as a steelmaking slag treatment.

The influence of MgO-type expansive agent incorporated in self-healing system of Engineered cementitious Composites

Engineered Cementitious Composites (ECCs) are found to be better replacements for traditional concretes due to their higher damage tolerance under loading, as well as the ability to induce multiple-cracking with a smaller width and potential crack healing capability. This paper presents the development and performance of an effective self-healing concrete system made of ECC and MgO-type expansive agent (MEA) (made of lightly burnt MgO powder). New measures were implemented in examining the performance of ECC-MgO self-healing system based on accelerated autoclave test to simulate the experimental results relevant to the field conditions. Test results suggested the best calcination system to be 900°C with 2h of holding time using 45µm particle size based on higher hydration activity of MEA in a powder state. Low calcium Class-F fly ash was found to be the best supplementary cementing materials (SCMs) to produce ECC-MgO system based on lower expansion effect of MgO. The high volume of fly ash (HVFA) was used to achieve very low expansion within the crack walls just to heal hairline micro-cracks in ECC-MgO self-healing system without jeopardizing the durability. Similar behavior was shown by the MgO in powder state in terms of loss of CO2 content and remaining hydration activity as well as after utilizing it in the ECC-MgO system in water and autoclave linear expansion tests coupled with scanning electron microscope (SEM) and thermogravimetric analyses (TGA). The higher flexural strength recovery of pre-cracked ECC-MgO prismatic specimens cured under accelerated autoclaved conditions compared to their pre-cracked ECC (without MgO) counterparts confirmed the self-healing capability and potential of the proposed ECC-MgO system.

EELS and electron diffraction studies on possible bonaccordite crystals in pressurized water reactor fuel CRUD and in oxide films of alloy 600 material

Abstract Experimental verification of boron species in fuel CRUD (Chalk River Unidentified Deposit) would provide essential and important information about the root cause of CRUD-induced power shifts (CIPS). To date, only bonaccordite and elemental boron were reported to exist in fuel CRUD in CIPS-troubled pressurized water reactor (PWR) cores and lithium tetraborate to exist in simulated PWR fuel CRUD from some autoclave tests. We have reevaluated previous analysis of similar threadlike crystals along with examining some similar threadlike crystals from CRUD samples collected from a PWR cycle that had no indications of CIPS. These threadlike crystals have a typical [Ni]/[Fe] atomic ratio of ∼2 and similar crystal morphology as the one (bonaccordite) reported previously. In addition to electron diffraction study, we have applied electron energy loss spectroscopy to determine boron content in such a crystal and found a good agreement with that of bonaccordite. Surprisingly, such crystals seem to appear also on corroded surfaces of Alloy 600 that was exposed to simulated PWR primary water with a dissolved hydrogen level of 5 mL H 2 /kg H 2 O, but absent when exposed under 75 mL H 2 /kg H 2 O condition. It remains to be verified as to what extent and in which chemical environment this phase would be formed in PWR primary systems.

Effect of Water Content, Temperature and NaCl on CO2 Corrosion of Carbon Steel (A106B) in Iraqi Crude Oil

An investigation was carried out to determine the corrosion rate of carbon steel (A 106 Grade B) as flow line in crude oil production with CO2 content employing three Iraqi crude oil (Kirkuk crude oil, Halfaya crude oil, and Rumalia crude oil) with identical produced water (brine) [1%NaCl, 2%NaCl, and 3%NaCl]. Experiments were performed in an autoclave test apparatus, crude oil-produced water mixtures, water cuts were (0, 10, 20, 30, 40, and 100%), and temperature (20, 40, 60°C). For all experiments, CO2 partial pressure was maintained at 4bar and rotational speed 500 rpm. The corrosion rates were determined by the weight loss method. The results revealed that the corrosion rate of carbon steel increased by increasing water cut and temperature, but decreased with increasing salt concentration for all types of crude oil. Rumaila crude oil exhibited the highest corrosion rate and Kirkuk crude oil exhibits the lowest corrosion rate while Halfaya crude oil exhibits a moderate corrosion rate.

Moisture absorption by molding compounds under extreme conditions: Impact on accelerated reliability tests

The Highly Accelerated Stress Test (HAST) [130°C/85%RH or 110°C/85%RH with applied bias voltage] or Autoclave test [121°C/100%RH] are well-accepted tests during qualification and reliability testing of automotive microelectronics. These tests are often preferred since results can be obtained relatively fast due to the high acceleration. On the other hand, there is a risk of accelerating non-relevant failure modes e.g. due to changes in material behavior under test conditions, which will not occur during application. However, predicting what happens under test conditions is not straightforward since one needs to understand material behavior under such extreme conditions. Especially the amount of water absorption, which is highly relevant for test result interpretation, is challenging to obtain at temperatures above 100°C, since here we deal with pressurized conditions.In this paper a novel, and straightforward, method is proposed to determine the moisture absorption under pressurized conditions. To verify the method, data obtained under pressurized conditions is compared to behavior under standard conditions. Under autoclave conditions it is shown that the moisture uptake at higher temperatures is much higher than predicted by extrapolation. The reported data can also be used to predict more reliably the moisture saturation level, and rate of moisture saturation during HAST.

Stability of Chromia (Cr2O3)-Based Scales Formed During Corrosion of Austenitic Fe-Cr-Ni Alloys in Flowing Oxygenated Supercritical Water

The comparative corrosion resistance of two high-chromium austenitic Fe-Cr-Ni alloys, namely Type 310S stainless steel (UNS S31008) and Alloy 33 (UNS R20033), was examined after exposure in supercritical water (25 MPa and 550°C), using a flow-loop autoclave testing facility operated at a flow rate of 200 mL/min. Electron microscopy techniques were used to determine links between the composition and structure of the Cr2O3-based oxide scale formed on both alloys and the difference in corrosion resistance observed. The weight change kinetics was distinctly different: progressively positive (weight gain) for Type 310S stainless steel and progressively negative (weight loss) for Alloy 33. The descaled weight loss was lower for Alloy 33, indicating improved corrosion resistance. This improved corrosion resistance was attributed to the improved stability of the Cr2O3-based scale that formed on Alloy 33 despite the negative weight change kinetics. The suitability of these alloys as candidate fuel cladding for the...

ПОРІВНЯЛЬНА ОЦІНКА ДІЇ ДЕЗІНФІКУЮЧИХ ЗАСОБІВ З МИЮЧИМ ЕФЕКТОМ ПРИ ЗНЕЗАРАЖЕННІ E. СOLI ТА S. АUREUS

A comparative analysis of the use detergents disinfectants with different active ingredients: heotsyd (polihexametylenhuanidin hydrochloride, benzalkonium chloride) virosan (alkildymetylbenzylamoniya chloride, glutaraldehyde) neohlor (sodium hypochlorite) orhasept (benzalkonium chloride, lactic acid) and determination of their minimum effective concentration and exposure required for removal of E. coli and S. aureus on test sites: stainless steel, tile, concrete, brick was were conducted. At sterilized in an autoclave test objects applied to 1 cm3 culture E. coli and S. aureus at a concentration of 2 billion. mikr.til per cm3. Contaminated test objects dried and placed into cuvettes horizontally and vertically and spray disinfectants applied explored solutions, while noting their exposure concentration and amount spent. Objects whish were exposure by the same scheme, but with using sterile water were used as control. After a certain period of time by sterile cotton swab from experimental and control test objects were taken probes. Then 1 cm3 initial suspension of each of these tubes were placed in the appropriate environment for 24 hours. at thermostat at 37 °C. By the changes in defined media presence or absence of these microorganisms were determined.Stated that disinfectants orhasept and virosan in 0.1% concentration and heotsyd neohlor in 0.5% concentration completely disinfected from E. coli and S. aureus on surfaces of the test objects for 10 min, confirms their detergent disinfectant effect. Effective concentrations of disinfectants regarding test organisms consistent with regulations for their use.

A Comparative Catalyst Evaluation for the Selective Oxidative Esterification of Furfural

Catalysts based on gold or other metals on different supports were studied in the selective oxidative esterification of furfural with methanol to methyl 2-furoate. Methyl 2-furoate can be used in specialty fragrances, a high added-value application. Catalyst evaluation and selection were performed using the Avantium quick catalyst screening (QCS) platform using industrially relevant conditions. The best performances were exclusively obtained with gold based catalyst supported on ceria or titania, though these catalysts showed rather poor behavior in tests with a different furfural to methanol ratio. Selected gold catalysts were studied subsequently in a conventional lab-scale autoclave under reaction conditions closer to those commonly applied in literature and effects of support type and preparation were included. For each of the two testing conditions a different catalyst was identified as the most optimal, which is explained by the strong chemisorption of furfural on the Au surface. Au/ZrO2 catalysts, identified as optimal in QCS tests, show also high performances (about 99 % yield) in autoclave tests, although a different preparation was employed.

Uniform corrosion of FeCrAl alloys in LWR coolant environments

The corrosion behavior of commercial and model FeCrAl alloys and type 310 stainless steel was examined by autoclave tests and compared to Zircaloy-4, the reference cladding materials in light water reactors. The corrosion studies were carried out in three distinct water chemistry environments found in pressurized and boiling water reactor primary coolant loop conditions for up to one year. The structure and morphology of the oxides formed on the surface of these alloys was consistent with thermodynamic predictions. Spinel-type oxides were found to be present after hydrogen water chemistry exposures, while the oxygenated water tests resulted in the formation of very thin and protective hematite-type oxides. Unlike the alloys exposed to oxygenated water tests, the alloys tested in hydrogen water chemistry conditions experienced mass loss as a function of time. This mass loss was the result of net sum of mass gain due to parabolic oxidation and mass loss due to dissolution that also exhibits parabolic kinetics. The maximum thickness loss after one year of LWR water corrosion in the absence of irradiation was ∼2 μm, which is inconsequential for a ∼300–500 μm thick cladding.

The corrosion resistance of Zr-0.7Sn-1Nb-0.2Fe-xCu-xGe alloys in 360 °C lithiated water

The corrosion behavior of Zr-0.7Sn-1Nb-0.2Fe-xGe-xCu alloys (x=0, 0.05, 0.1, 0.2, wt%) and the microstructures of the oxide film formed on the specimens were investigated in lithiated water at 360°C by autoclave tests. Results show that the corrosion resistance of the Zr-0.7Sn-1Nb-0.2Fe alloy is remarkably improved with 0.05% Cu and 0.05% Ge addition, since a small amount of Cu and Ge can dissolve in α-Zr matrix and Cu- or Ge-containing Zr(Nb,Fe)2 second phase particles(SPPs) can delay the microstructural evolution of oxide film. But the coarse tet-Zr2Cu and tet-Zr3Ge SPPs, which will be formed by the further increase of Cu and Ge content, are disadvantageous to the corrosion resistance of the alloys.

Effect of Thermal Pretreatment on the Corrosion of Stainless Steel in Flowing Supercritical Water

The effect of high-temperature microstructure degradation (thermal ageing) on the corrosion resistance of austenitic stainless steels in supercritical water (SCW) was evaluated in this study. Mill-annealed (MA) and thermally treated (TT) samples of Type 316L and Type 310S stainless steel were exposed in 25 MPa SCW at 550°C with 8 ppm dissolved oxygen in a flowing autoclave testing loop. The thermal treatments applied to Type 316L (815°C for 1000 hr + water quench) and Type 310S (800°C for 1000 hr + air cool) were successful in precipitating the expected intermetallic phases in each alloy, both within the grains and on the grain boundaries. It was found that a prolonged time at relatively high temperature was sufficient to suppress significant compositional variation across the various intermetallic phase boundaries. This paper presents the results of the gravimetric analysis and oxide scale characterization using scanning electron microscopy (SEM) coupled with X-ray energy-dispersive spectroscopy (EDS). The role played by the fine precipitate structure on formation of the oxide scale, and thus corrosion resistance, is discussed. The combined role of dissolved oxygen and flow (revealed by examining the differences between Type 316L samples exposed in a static autoclave and in the flowing autoclave loop) is also addressed. It was concluded that formation of intermetallic phase precipitates during high-temperature exposure is not likely to have a major effect on the apparent corrosion resistance because of the discontinuous nature of the precipitation.

Performance of iron–chromium–aluminum alloy surface coatings on Zircaloy 2 under high-temperature steam and normal BWR operating conditions

Iron-chromium-aluminum (FeCrAl) coatings deposited on Zircaloy 2 (Zy2) and yttria-stabilized zirconia (YSZ) by magnetron sputtering have been tested with respect to oxidation weight gain in high-temperature steam. In addition, autoclave testing of FeCrAl-coated Zy2 coupons under pressure-temperature-dissolved oxygen coolant conditions representative of a boiling water reactor (BWR) environment has been performed. Four different FeCrAl compositions have been tested in 700 °C steam; compositions that promote alumina formation inhibited oxidation of the underlying Zy2. Parabolic growth kinetics of alumina on FeCrAl-coated Zy2 is quantified via elemental depth profiling. Autoclave testing under normal BWR operating conditions (288 °C, 9.5 MPa with normal water chemistry) up to 20 days demonstrates observable weight gain over uncoated Zy2 simultaneously exposed to the same environment. However, no FeCrAl film degradation was observed. The 900 °C eutectic in binary Fe–Zr is addressed with the FeCrAl-YSZ system.

Ceramic coating for corrosion (c3) resistance of nuclear fuel cladding

In an attempt to develop a nuclear fuel cladding that is more tolerant to loss-of-coolant-accidents (LOCA), ceramic coatings were deposited onto a ZIRLO™11ZIRLO is a trademark of Westinghouse Electric Co. substrate by cathodic arc physical vapor deposition (CA-PVD). The coatings consisted of either Ti1–xAlxN or TiN ceramic monolithic layers with a titanium bond coating layer as the interlayer between the ceramic coating and the ZIRLO™ substrate to improve coating adhesion. Several coating deposition trials were performed investigating the effects of bond coating thickness (200–800nm), ceramic coating thickness (4, 8 and 12μm), substrate surface roughness prior to deposition, and select coating deposition processing parameters, such as nitrogen partial pressure and substrate bias, in order to optimize the coating durability in a corrosion environment. Corrosion tests were performed in static pure water at 360°C and saturation pressure (18.7MPa) for 3days. The optimized nitride-based ceramic coatings survived the autoclave test exposure showing very low weight gain of 1–5mg/dm2 compared to the uncoated ZIRLO™ samples which showed an average weight gain of 14.4mg/dm2. Post-corrosion exposure analytical characterization showed that aluminum depletion occurred in the TiAlN coated samples during the autoclave corrosion test, which led to the formation of the boehmite phase that degraded the corrosion durability of some of the TiAlN samples. However, by eliminating the aluminum content and depositing TiN, the boehmite phase was prevented from forming. Best results in TiAlN coated samples were obtained with 600nm Ti bond coating thickness, 12µm coating thickness and 0.25µm substrate surface roughness (E14). Results are discussed in terms of the capability of TiN and Ti1–xAlxN coatings to improve the high temperature corrosion resistance and oxidation resistance of zirconium alloy cladding.

Solder Ball Robustness Comparison between SAC 387 and Polymer Solder Balls under AC and TC Reliability Test

Environment and the health concerns due to the hazardous effects of lead resulted in significant activities to find a replacement for lead-contained solders for electronics industrial. Majority of the semiconductor industrial are now replacing lead solders with Tin-Silver-Copper (SAC 387) solder balls. However, dropped balls in SAC 387 for Ball Grid Array (BGA) products due to poor solder joint strength caused by high thermal stress are a major concern in the semiconductor industries. Polymer core inside the solder ball (polymer core/Cu/Sn) is thus integrated to improve the solder ball joint strength. The function of polymer core inside the solder ball is to absorb and released the stress better as compared to the SAC 387 solder ball. Since the diffusion rate of Cu is faster than the diffusion rate of Sn, hence, this could caused the Kirkendall voids tends to form in between the Cu and Sn IMC layer. This would affect the solder ball joint strength and causing drop balls issue. By implement with an extra of Ni layer to the polymer core solder ball (core/Cu/Ni/Sn), could reduce the diffusion from Cu to Sn, thus to overcome the Kirkendall voids and to further improve the solder ball joint strength. This research work studies the performance of the solder ball shear strength of the two types of solder balls applied to MAPBGA device. In this research, both SAC 387 and polymer solder balls were went through under AC (Autoclave) and TC (Temperature Cycle) reliability test up to 144 hours and 1000 cycles, respectively. Solder ball shear strength test was conducted via Dage 4000 series bond tester. From the research work results of the two types of solder balls, the ball shear strength were decreased with an increased of aging and cycles. Overall, it can be concluded that the polymer core solder ball with an additional of Ni layer showed better performance than the polymer core without Ni layer and SAC 387 solder balls, after subjected to the AC and TC reliability test.

Sterile reprocessing of surgical instruments in low- and middle-income countries: A multicenter pilot study

Surgical site infections increase the morbidity, mortality, and costs associated with surgical care. An estimated 96.2 million surgical procedures are performed in low- and middle-income countries (LMICs) each year. This pilot study assessed the steam sterilization aspect of the surgical instrument reprocessing practice in LMIC hospitals. Surgeons representing 26 hospitals in 9 different LMICs were consented to test the single most frequently used autoclave in their respective surgical departments. Participants conducted 10 chemical integrator tests and recorded the total cycle time, exposure temperature, and pressure on each test. Data were analyzed with descriptive statistics and reviewed by medical reprocessing experts. Nine of the 26 (35%) study sites representing 7 countries returned their autoclave data and test strips (n=90). Of the sites, 78% obtained acceptable readings on all 10 tests. When the data were compared against the recommended parameters for sterility, the results were less favorable. All 90 tests had at least 1 variable not within the target exposure time, temperature, or pressure. This pilot study presents concerns in regard to the effectiveness of steam autoclaves used in LMIC hospitals and the subsequent risks this presents to surgical patients. We acknowledge the resource limitations in many LMIC hospitals. However, the international medical community must ensure that basic sterile practice guidelines are adhered to despite these constraints.

Structure and Fracture of Zirconium Alloys After Oxidation Under Various Conditions

The microstructure and mechanical properties of oxide films on specimens of cladding tubes from zirconium alloys with different chemical compositions are studied after autoclave tests and high-temperature oxidation simulating loss of coolant accidents. Quantitative investigation of the structure is performed and fracture surfaces of oxidized specimens are analyzed. The main factors responsible for the embrittlement of the alloys are determined.

Hydrothermal corrosion of SiC in LWR coolant environments in the absence of irradiation

Assessment of the thermodynamics of SiC corrosion under light water reactor coolant environments suggests that silica formation is always expected in the range of applicable pH and potential. Autoclave testing of SiC-based materials in the absence of ionizing radiation was performed. The kinetics data from these tests, when compared with kinetics of silica dissolution in water and post-exposure characterization of SiC samples, suggest that oxidation of SiC to form silica is the rate-limiting step for recession of SiC in high temperature water. Oxygen activity in water was determined to play an important role in SiC recession kinetics. A simplified model of a power loop shows the effect of silica dissolution from the hot region (resembling fuel) and deposition in the cold regions.

Synthesis of stearic acid modified ground calcium carbonate (SA-GCC) hybrid material and properties of SA-GCC/epoxy composites coating

Ground calcium carbonate (GCC) was modified by stearic acid (SA), and SA-GCC hybrid materials were obtained. The modified GCC (SA-GCC) were characterized by infrared spectroscopy (FTIR), thermal gravimetric (TGA), particle size analysis and hydrophobicity. The results showed that SA was chemically bound onto the surface of GCC. GCC (60 wt %) modified with 1 wt % of SA was filled into epoxy matrix to prepare composite coating by high-pressure spraying method and thermal curing process. The properties of SA-GCC/epoxy composites coating, such as adhesion, corrosion protection, were investigated by electrochemical impedance spectroscopy (EIS), autoclave testing and others instruments. The results demonstrated that SA-GCC/epoxy composites coating possess improved adhesion, corrosion resistance and thermal stability. High temperature and pressure testing indicated that the performance of such coating increased greatly.