Mechanoluminescent Visualization of Crack Propagation for Joint Evaluation

In this study, methods for the mechanoluminescent (ML) visualization of crack propagation and mechanical behavior to evaluate adhesive joints are ...

National Institute of Advanced Industrial Science and Technology (AIST)

A selective carbon monoxide (CO) sensor was developed by the use of both of CuCrFeO and CoCrFeO as the sensing electrode (SE) for yttria-stabilized zirconia (YSZ)-based potentiometric sensor. The sensing-characteristic examinations of the YSZ-based sensors using each of spinel oxides as the single-SE sensor showed that CuCrFeO-SE had the ability to detect CO, hydrocarbons and NO gases, while CoCrFeO-SE was sensitive to hydrocarbons and NO gases. Thus, when both SEs were paired as a combined-SEs sensor, the resulting sensor could generate a selective response to CO at 450 °C under humid conditions. The sensor was also capable of detecting CO in the concentration range of 20-700 ppm. Its sensing mechanism that was examined via polarization-curve measurements was confirmed to be based on mixed-potential model. The CO response generated by the combined-SEs sensor was unaffected by the change of water vapor concentration in the range of 1.3-11.5 vol% HO. Additionally, the sensing performance was stable during 13 days tested.

YSZ-based sensor using Cr-Fe-based spinel-oxide electrodes for selective detection of CO.

The goal of this study was to investigate the chemical alteration of a dental alloy surface by alumina air-abrasion and its effect on bonding to resin cement. Alumina air-abrasion was carried out on an Ag-Pd-Cu-Au alloy. The surface morphology and chemical state of the abraded alloy were characterized. The effect of the air-abrasion on the shear bond strength between the alloy and a methyl methacrylate/tri-n-butyl borane (MMA/TBB) resin cement with some primers was evaluated. The surface characterization revealed that the alumina air-abrasion mechanically roughened and chemically altered the surface. The chemical alterations had two effects: (1) abraded alumina particles remained on the alloy surface and (2) copper ions were oxidized in the alloy surface. As the result, the shear bond strength test indicated that 10-methacryloyloxydecyl dihydrogen phosphate (MDP) contained primer worked with the abraded alloy surface, whereas it did not work with the non-abraded alloy surface.

Chemical alteration of Ag-Pd-Cu-Au alloy surface by alumina air-abrasion and its effect on bonding to resin cement.

The aim of this paper is to study changes in the Ag-Pd-Cu-Au alloy surfaces by alumina air-abrasion process and effect of those changes on the adhesive bonding characteristic. Surface roughness, surface composition and chemical state of the alumina air-abraded alloys were analyzed by a confocal laser scanning microscope, an energy dispersive X-ray spectroscopy and an X-ray photoelectron spectroscopy. The results showed that the alumina air-abrasion changed the alloy surface by mechanical roughening, alumina remain and copper oxidation. Effect of the changes in the alloy surface on the adhesive bonding characteristic was examined by using a methyl methacrylate/tri-n-butylborane derivative (MMA/TBB) resin cement with the 10-methacryloyloxydecyl dihydrogen phosphate (MDP) contained primer. The shear bond strength test results indicated that the surface oxidation by the abrasion is the main contributor that improved the adhesive bonding rather than other effects such as mechanical roughening or alumina remain.

Adhesive bonding of alumina air-abraded Ag-Pd-Cu-Au alloy with 10-methacryloyloxydecyl dihydrogen phosphate.

This study aims to develop a corona discharge process for a surface treating a glass-ceramic, feldspar porcelain, to improve its bonding to a resin cement with a silane-coupling agent. Corona discharge, a type of plasma process, was performed using a custom-made device on a porcelain surface at temperatures ranging from 25 to 300 °C, for specific treatment times in air. The porcelain was then subjected to a post-heat-treatment at 600 °C to condition the surface state. The resulting surface was primed with a silane-coupling-agent followed by cementing using a resin cement to measure the shear bond strength (SBS). To investigate the effect of surface modifications by the corona discharge treatment, the porcelain was characterized by surface roughness, contact angle, and an X-ray photoelectron spectroscopy analyses. The SBS for the corona-discharge-treated porcelain increased with an increase in treatment-temperature and -time, and reached the maximum value at 200 °C and 5 min. The post-heat-treatment improved the bond durability after thermocycling. The SBS for the corona-discharge-treated porcelain was then compared to that of a conventional hydrofluoric-acid-treated one, which showed that the SBSs were comparable. The results of the surface characterizations indicated that the corona discharge treatment generated silanol groups on the porcelain surface giving hydrophilic properties without roughening the surface. It was found that the corona discharge treatment generates silanol groups on the porcelain surface, resulting in an increased SBS. This study is the first to demonstrate that corona discharge treatment is effective for improving bond strength through the modification of the surface of glass-ceramics.

Surface modification of feldspar porcelain by corona discharge and its effect on bonding to resin cement with silane coupling agent.

Hydrofluoric acid has been used to remove salivary contamination in dental glass-ceramics before bonding treatment. However, alternative methods are required because hydrofluoric acid is harmful. This study examined the cleaning effects of phosphoric acid and sodium hydroxide on glass-ceramics for bonding pre-treatment.

Effect of phosphoric acid and sodium hydroxide on cleaning and bonding of saliva-contaminated feldspar porcelain.

Non-destructive testing of carbon-fiber-reinforced plastic (CFRP) laminates with bidirectional fiber bundles (twill-weave) using a mechanoluminescence (ML) technique was proposed. The dynamic strain distributions and fracture phenomena of the CFRP laminates in the tensile testing were evaluated by the fabricated ML sensor consisting of SrAlO:Eu (SAOE) powder and epoxy resin. The ML images for the ML sensor attached to the CFRP laminates with bidirectional fiber bundles gave a net-like ML intensity distribution similar to the original twill weave pattern. Specifically, it was found that the ML intensity on the longitudinal fiber bundle, which is the same as the tensile direction, is higher than that on the transverse fiber bundle. This indicates that the ML sensor can visualize the load share between fiber bundles in different directions of the CFRP laminate with high spatial resolution. Meanwhile, the ML sensor could also visualize the ultrafast discontinuous fracture process of the CFRP laminates and its stress distribution. The amount of SAOE powder in the ML sensor affects the tracking performance of the crack propagation. A higher SAOE amount leads to a fracture of the ML sensor itself, and a lower SAOE amount leads to poor ML characteristics.

Yuki Fujio

Sensing System Research Center (SSRC)

National Institute of Advanced Industrial Science and Technology (AIST)

Mechanoluminescent Visualization of Crack Propagation for Joint Evaluation

Yuki Fujio

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Sensing System Research Center (SSRC)

National Institute of Advanced Industrial Science and Technology (AIST)

Mechanoluminescent Visualization of Crack Propagation for Joint Evaluation

Sensing System Research Center (SSRC)