Blister Area Research Articles

The Vibration Dynamic Model for Blister Detection in Medium-Density Fiberboard

Ultrasonic detection is currently used in the industry of medium-density fiberboard to detect blister defects. Due to the small detection area of a single sensor, multiple sensors need to be used, which results in high costs. Starting from elastic thin plate vibration theory, this paper builds a vibration dynamic model to detect blisters. The size and depth of the blister area can be established by determining the natural frequency of the thin plate vibration in the blister area. In this model, if the elastic modulus and density are known, the natural frequency of the thin plate vibration at the blister place is directly proportional to the blister depth and inversely proportional to the square of the blister radius. The size and depth of the blister can be determined by measuring the first third-order natural frequency of this area of research. A total of 25 specimens with blister sizes and depths were simulated, and the natural frequencies of the specimens were measured. Subsequently, the detection model was verified by comparing its experimental data with theoretical values. The theoretical value was highly consistent with the measured data. The measured values of the first, second, and third-order natural frequencies were slightly smaller than the theoretical calculated values, with average relative deviations of −1.6%, −1.34%, and −1.03%, respectively. As the order progressed, the deviation exhibited a downward trend, and the third-order natural frequency displayed the smallest deviation and highest accuracy. The proposed vibration dynamic model can detect larger blister areas by measuring the natural frequency, which can overcome the shortcomings of small ultrasonic detection areas in current actual industries. Thus, the practical online blister detection device is expected to be further developed.

Microstructure and mechanical properties of hydride blisters formed on Zircaloy-4 claddings

To assess the microstructural and mechanical characteristics of hydride blisters formed on Zircaloy-4 tubes, we employ the electron backscatter diffraction (EBSD) analyses and micro-cantilever failure tests directly on the hydride blister (HB) area. In the HB area, more than 70% of the blister area is characterized to be δ-hydride, and the HB area does not favor the orientation relation ((101¯1)α//(001)δ, [12¯10]α//[1¯10]δ) that is otherwise well-matched in the Zr matrix area. The geometrically necessary dislocation density is observed in the entire blister area, indicating a large amount of strain throughout the blister area. Also, the deformation strain is concentrated in both the hydride and α-Zr phases of HB areas; however, the hydride underwent intensive deformation in the Zr matrix. The average fracture toughness of the hydride blister area obtained through the micro-cantilever test is 1.81 MPam, indicating a brittle fracture that may threaten the integrity of spent nuclear fuel claddings.

Effect of different blister positions on void fraction distribution under subcooled boiling conditions in narrow rectangular channel

Cladding blistering of plate fuel element is one of the common accidents in the operation of research reactor. At present, there was little research on coolant flow boiling under blister conditions. However, the void fraction distribution of coolant under boiling condition was closely related to CHF. To study the effect of a blister on the void fraction under subcooled boiling, a numerical method was used to simulate the blister phenomenon in the narrow rectangular channel. The Euler two fluid model was adopted in this study and the modified RPI model was used to simulate flow boiling. The calculation results showed that a blister on the heating surface could lead to a significant change in the void fraction distribution near the blister area. The distribution trend of the void fraction in the rear of the blister was different under different axial blister position conditions. In general, the closer the axial position of the blister was to the outlet of the channel and the closer the lateral position was to the narrow edge of the narrow rectangular channel, and the larger the peak value of the local void fraction was. The local maximum of the void fraction could rise to over 0.8, and heat transfer deterioration may occur in the blister area.

The effect of pre-damage distribution on deuterium-induced blistering and retention in Tungsten

Heavy ions have been widely used to simulate the effect of neutron irradiation-induced crystal defects on the plasma-wall interaction in the future fusion device. In this work, energetic argon ions were utilized to damage tungsten with the different pre-damage distributions. The pre-damage distribution is controlled by tuning ion energy and fluence. After exposure to deuterium plasma, the pre-damaged tungsten targets were analyzed to explore the impact of pre-damage distribution on deuterium-induced surface blistering and retention. Surface observation results reveal that increasing pre-damage depth and peak dpa significantly reduce the surface blister's area density, especially in diameters below ten micrometers. Meanwhile, thermal desorption spectra indicate that the given change in the pre-damage distribution barely change the type of irradiation-induced defects. The role of pre-damage increases in deuterium trapping and aggregation is discussed based on the experimental results.

Corrosion Acceleration Test on Weathering Steel and Paint-coated Steel for Bridge Structural Members

A new accelerated corrosion test authorized as ISO16539 Method B in 2013 has shown a good correlation with corrosion behavior in an actual corrosive atmospheric environment. This study aims to extend the application of this method to steel bridge members. The corrosion acceleration tests by the ISO 16539 Method B to weathering steel without anti-corrosive coating and paint-coated steel were conducted through 6 months of the test periods. A series of fundamental studies were conducted to clarify the characteristics of this test in the durability evaluation of the steel used for bridge structural members by comparing the results of the atmospheric exposure test. The accelerated test of 168 days produced the thickness reduction by 10 to 14 times larger than the exposure test of 365 days to the weathering steel. The blister area of the paint-coating as a measure of the paint degradation by the accelerated test was 11 to 14 times larger than the exposure test of 365 days to paint-coated steel. These results showed the effectiveness of the accelerated test by ISO16539 Method B to evaluate the degradation characteristics of the weathering steel and the paint-coated steel.

Phytophotodermatitis: A Case Report

A rare phototoxic dermatological reaction seen in Indian Sub-continent, known as Phytophotodermatitis, occurs with exposure to ultraviolet light after contact with certain plant chemicals. Phytophotodermatitis named from the terms ‘phyto’ means plant, ‘photo’ means light, and ‘dermatitis’ means skin inflammation. The signs and symptoms of Phytophotodermatitis typically initiated 24 hours after comes in contact with skin, and the peak is reached between 48 to 72 hours. The indications may be from mild or severe. The signs are redness, tenderness, burning sensation, pain, inflammation, itching, blistering, thickened layer of skin after blisters rupture. The area of blisters is usually asymmetrical in shape. These are seen in the areas of the skin, that were exposed to the chemical. For example, the drip form of blister seen in the skin if it is exposed to fruit juice. If the skin were brushed against a plant, it would show streaks like pattern. Though the early symptoms subside, within 7-14 days, signs of blackening of the skin may show hyperpigmentation. This stage of Phytophotodermatitis is known as post-inflammatory pigmentation and might last for many months. In some cases, the affected person will have a very mild inflammatory reaction, if they are exposed to sunlight, while some may not even know that they experienced a reaction. The hyperpigmentation is the initial sign to know that they have got Phytophotodermatitis. Initial symptoms get aggravated because of wet skin, sweat and heat. Darkening of skin-colour is observed in the persons while they are exposed to sunlight. In this case, we are reporting about a patient having this condition and the cause for the occurrence.

Effect of Surface Roughness on Hydrogen-Induced Blister Behavior in Pure Iron

The effect of surface roughness on hydrogen-induced blister behavior in pure iron was explored using optical microscopy and microcomputerized tomography. Hydrogen was introduced into the samples by electrochemical precharging methods with various hydrogen charging times. It is found that grinded surface exhibits higher roughness and compressive residual stress compared to those of polished surface. With increasing hydrogen charging time, hydrogen-induced blister height, blister width and blister area fraction increase, regardless of the grinded surface and polished surface. Further, hydrogen blister height and width of grinded surface are comparative to polished surface under the same hydrogen charging time. However, the blister area fraction and the number of blister on polished surface are considerably higher than the grinded surface, indicating that polished surface is more susceptible to the formation of blisters than that of grinded surface, both of surface and interior of the samples. This is dominantly rationalized in terms of the suppression effect of hydrogen invasion in grinded surfaces due to their higher residual compressive stress and higher dislocation density.

Comparison of the crack-growth rates for full-encirclement and patch composite repairs

In the United States, full-encirclement bonded composite repairs have been an allowable repair method for pressure vessels since 1991. These repairs are used to reinforce damaged pressure vessels by wrapping composite completely around the vessel wall. Installing a full-encirclement repair becomes expensive and cumbersome for larger diameter vessels. And so, a patch size repair becomes preferred for use on bigger vessels. This composite patch bonds over the desired area on the damaged wall instead of completely wrapping the circumference of the vessel. In this paper, we investigate the crack propagation behavior of two repair types used to repair through-wall defects on a pressure vessel. An optical method has been adopted which monitors the crack propagation by observing the out-of-plane deflection of the blister area. It was found that the two repair types have similar crack propagation behavior during fatigue testing.

Cleaning of thick films using liquid jets

Cleaning of process plants is important to ensure product purity and safety. Cleaning is however expensive with respect to energy, waste and time. It is important to be able to minimise losses from cleaning, by maximising product recovery and reducing waste. Viscous food and personal care products can form thick layers on process surfaces. Cleaning of a surface by a water jet has been studied here. Two modes of cleaning are identified experimentally; for thin films, cleaning is by formation of a crater that expands with time, whilst for thick films a ‘blister’ forms in which water spreads underneath the deposit. The blister eventually cleans, but over a much longer timescale than for the thinner film. The cleaned area after 10 seconds is comparable in size to the blister area after less than half a second of cleaning. This behaviour has implications for the cleaning of real systems.

The study of irradiation damage induced by proton in metallic glass Ni62Ta38 and metal W

The protons with an energy of 250 keV were used to irradiate metallic glass Ni62Ta38 and metal W, the changes in structure and surface morphology of both the materials were compared, and their performances against the irradiation were evaluated, in order to provide the reference for the possibility of application of metallic glass Ni62Ta38 in irradiation environment. The results showed that after the proton irradiation, metallic glass Ni62Ta38 still maintained its good amorphousness without obvious irradiation damage on its surface. Meanwhile, stress was generated in metal W, and its crystalline size, micro-strain and dislocation line density varied undulately with the increase of fluence. When the irradiation fluence was 1.0 × 1018 ions/cm2, large area of blisters were formed on the surface of metal W. The surface roughness of metal W increased with the fluence. Compared with metal W, the proton irradiation resistance of metallic glass Ni62Ta38 was better.

Effect of weld line direction and paint orientation on corrosion and paint deterioration characteristics of welded part of steel

ABSTRACTOne thousand two hundred cycles of accelerated exposure experiment with combined salt water spray simulating atmospheric corrosion was performed for investigating the effect of weld line direction and paint orientation on the corrosion and paint deterioration characteristics of welded part of the steel. The corrosion depth of the weld toe of transverse weld line became 1.35 times as large as that of the base metal part because of the remained salt water on the weld toe. The coating thickness at the weld toe became thin by vertically painting on the transverse weld line. When the scribe line was installed at the thin painted weld toe under the transverse weld line, the paint blister area became 15% larger than that of the base metal part. The paint coating thickness at the weld toe in different weld line directions and paint orientations should be confirmed and ensured from the viewpoints of manufacturing and maintaining steel structures.

Deformation characteristic and mechanism of blisters in cement concrete bridge deck pavement

The waterproofing membrane applied on cement concrete bridge deck usually experiences small uplift blisters, which leads to serious corrosive problems when water infiltrates into the bridge deck through the blister area. It is very important to reveal the formation and propagation of the blister for decreasing the damage of bridge deck pavement. In this paper, the environmental simulation blister test is proposed originally, and MatchID-3D (MTI-3D) structural deformation analysis system is adopted to measure the blister deformations. The deformation characteristic and mechanism of the blister are investigated. The test results show that the stages of blister deformation can be determined according to the deflection rate. The deflection deformation of the blister is a rapid process happening mainly in the third stage, while the debonding deformation is a relatively stable and long-term process. The test temperature, initial debonding aperture, and water have great influences on the failure time, meanwhile the former two factors also affect the total debonding length seriously. An improved blister test method is developed in this paper to accurately study the blister deformation under different environmental conditions, which helps to determine effective measures to eliminate the blister in bridge deck pavement.

Deterioration Behaviors of Overlapping Layers between Al-5Mg Alloy Thermal Spray Coating and Heavy-Duty Paint Coating

The objective of this study is to clarify the deterioration behaviors of overlapping layers between Al-5Mg alloy thermal spray coating and heavy-duty paint coating. Combined cyclic corrosion tests were carried out on common carbon steel plates with overlapping layers. To evaluate the effective area of the sacrificial anode reaction caused by the thermal spray coating, machined straight-line defects with widths of 0.2, 6 and 12 mm were introduced in the overlapping layer. The experimental results indicated that the layers began to deteriorate from the lower part of the thermal spray coating along the defects. The deterioration of the thermal spray coating was accelerated by the sealing treatment. The blister area and height at the overlapping layer were significantly different depending on the sealing treatment.

Influences of carbon and silicon on blister formation in scale surface during high temperature oxidation of carbon steels

The in-situ blistering phenomena of the scale ‘surface’ was investigated on three carbon steels with respect to carbon and silicon concentrations, such as 0.05 wt%C, 0.2 wt%C, and 0.2 wt%C-0.2 wt%Si. The oxidation and blistering kinetics and blister area fraction during high temperature oxidation were analyzed. The average thickness of the surface scale by oxidation during isothermal holding from 800 to 1200 °C in dry air was observed to decrease when the amount of carbon increased and/or when Si was inserted additionally. Thus, the blistering behavior depended primarily on a change in oxidation temperature (T ox ) as well as amounts of carbon and silicon in the matrix. It is also revealed that such blister formation would be triggered by growth of internal stress and active generations of CO and/or CO2 gases at the interface between the scale and matrix since carbon would result in an increase in the blister formation by generating CO and/or CO2 gas. In addition, silicon might play an important role in preventing the blister formation at T ox below 900 °C by reducing the thickness of the surface scale whilst silicon might enhance the blister formation by means of the appreciable micro-void formation in the scale layer at T ox higher 900 °C.

Study of irradiation damage induced by He2+ ion irradiation in Ni62Ta38 metallic glass and W metal

Metallic glasses are considered to possess good resistant against irradiation due to their inherent structural long-range disorder and a lack of grain boundaries. The He2+ with an energy of 300keV was used to irradiate Ni62Ta38 binary metallic glass to investigate its resistance against the irradiation, and the irradiated behaviour of the metallic glass was compared with that of W metal. The irradiation fluence range over 2.0×1017ions/cm2–1.6×1018ions/cm2. The TEM results show that nanocrystals of μ-NiTa phase and Ni2Ta phase appeared in Ni62Ta38 metallic glass under the irradiation fluence of 1.6×1018ions/cm2. The SEM results show that the surfaces of Ni62Ta38 metallic glasses maintained flat and smooth, whereas a large area of blisters with peeling formed on the surface of W metal at the irradiation fluence of 1.0×1018ions/cm2. It indicates that the critical irradiation fluence of surface breakage of the Ni62Ta38 metallic glass is higher than that of W metal. After the irradiation, stress was generated in the surface layer of W metal, leading to the increase of the hardness of W metal.

Sudden edematous exudative erythema in a waterfall pattern

A 48-year-old man presented to the emergency department because of a sudden, widespread, painful skin rash that started 18 hours after a bath. With no remarkable personal medical history, he was referred to the Department of Dermatology for a suspected thermal burn. The patient stated that he had taken a shower with an infusion of fig leaves followed by sun exposure, which was intended to be a purifying treatment. The physical examination revealed erythematous and edematous lesions with some areas of blistering and exudation located exclusively in sun-exposed areas. The lesions had a “waterfall” pattern on the back (Fig 1) and a linear pattern on the lower extremities (Fig 2, Fig 3). Treatment was initiated with oral corticosteroids, topical agents, and warm moist zinc sulfate compresses, achieving complete resolution after 2 weeks. 1.Based on the patient's history and the photographs, what is the most likely diagnosis? A.Irritant contact dermatitis B.Allergic contact dermatitis C.Phytophotodermatitis D.Solar urticaria E.Thermal burn 2.What is the cause of this presentation? A.Inflammatory response of the skin to irritant exposure B.Skin reaction to allergen exposure from the infusion C.Plant-derived phototoxic furocoumarins followed by sunlight exposure D.Ultraviolet radiation or visible light E.Burn resulting from contact with a hot boiled infusion Fig 2 View Large Image Figure Viewer Download Hi-res image Fig 3 View Large Image Figure Viewer Download Hi-res image

セルオートマトンによる塗膜下腐食シミュレーション手法に関する研究（第1報：スクライブ塗装鋼板の解析）

An underfilm corrosion simulation method for epoxy coated steel panels in ship’s water ballast tanks (WBT) has been developed. The incubation and extension of coating failure are simulated by using 2-dimensional cellular automaton method, and the steel diminution is simulated by modifying the corrosion model proposed by Kawamura et al. (2015). Analysis parameters are determined by using the results of onboard exposure and cyclic corrosion tests performed by Shiotani et al. (2014). The change in corroded surface shape of epoxy coated and scribed steel panels made of conventional steel and corrosion resistant steel (CRS) exposed in an ore carrier’s WBT for 4.8 years is simulated. The simulated coating deterioration (blister) area and the corroded surface profile agree well with those measured. This demonstrates the effectiveness of the developed simulation method and the determined parameters. The differences in analysis parameters between conventional steel and CRS suggest that CRS can reduce the harmful effect of the active corrosion region on the remaining coating life at the blister’s frontline and the corrosion under the blister.

Desmoglein 3 Inhibits Keratinocyte Migration by Suppressing p38MAPK Activity

The desmosomal transmembrane adhesion molecule desmoglein 3 (Dsg3) is required for strong keratinocyte cohesion. Recently, we have shown that Dsg3 loss of function, either by siRNA silencing or by peptides interfering with Dsg3 binding, increases the activity of p38MAPK. In this study, we aim to investigate the physiological role of Dsg3‐dependent p38MAPK suppression. Dsg3‐deficient mice display repetitive skin erosions most of which rapidly heal spontaneously. In lysates from wound biopsies but also from perilesional areas, p38MAPK activation was detectable compared to control animals. Similarly, in skin biopsies of pemphigus patients which suffer from impaired cell cohesion due to autoantibodies targeting Dsg3, p38MAPK activity was increased in areas of epidermal blistering. This led us to speculate that Dsg3 regulates wound repair in a p38MAPK‐dependent manner. Indeed, silencing of Dsg3 resulted in increased p38MAPK activity which was paralleled by enhanced migration speed. In line with this, scratch wounded keratinocyte monolayers exhibited p38MAPK activation in cells lining the wound edge. Importantly, migration was efficiently blocked by inhibition of p38MAPK both in control and Dsg3 knockdown keratinocytes. These data indicate that Dsg3 via p38MAPK inhibition prevents a switch from an adhesive to a migratory keratinocyte phenotype. Upon wounding, impaired Dsg3 adhesion may thus favor wound closure by facilitating p38MAPK‐dependent migration.

Pressure-assisted fabrication of organic light emitting diodes with MoO3 hole-injection layer materials

In this study, pressures of ∼5 to ∼8 MPa were applied to organic light emitting diodes containing either evaporated molybdenum trioxide (MoO3) or spin-coated poly(3,4-ethylene dioxythiophene) doped with poly(styrene sulphonate) (PEDOT:PSS) hole-injection layers (HILs). The threshold voltages for both devices were reduced by about half, after the application of pressure. Furthermore, in an effort to understand the effects of pressure treatment, finite element simulations were used to study the evolution of surface contact between the HIL and emissive layer (EML) under pressure. The blister area due to interfacial impurities was also calculated. This was shown to reduce by about half, when the applied pressures were between ∼5 and 8 MPa. The finite element simulations used Young's modulus measurements of MoO3 that were measured using the nanoindentation technique. They also incorporated measurements of the adhesion energy between the HIL and EML (measured by force microscopy during atomic force microscopy). Within a fracture mechanics framework, the implications of the results are then discussed for the pressure-assisted fabrication of robust organic electronic devices.

Adhesion and Puncture Strength of Polyurethane Coating Used to Mitigate Tin Whisker Growth

Reliability of conformal coatings used to mitigate tin whisker growth depends on their ability to contain tin whiskers. Two key material properties required to assess the reliability of a polyurethane coating are documented experimentally: adhesion strength and puncture strength. A modified blister test using a predefined blister area is employed to assess the adhesion strength and a puncture test is employed to evaluate the puncture strength of the coating. After measuring the properties at time zero, the coatings are subjected to accelerated testing conditions (high temperature/humidity storage and temperature cycling) and the degradations of the coating properties are documented.