Barrier Coat Research Articles

Corrosion of Potential First Stage Blade Materials in Simulated Supercritical CO2

ABSTRACT Global power consumption is predicted to double by 2050, notably driven by the transportation and energy sectors necessitating limitations of emissions. Due to its compact turbomachinery, better thermal efficiency, and simpler layout, supercritical-CO2 cycles have received attention, with numerous variations proposed (either indirect-fired/closed cycles or direct-fired-open cycles). One technical challenge is degradation pathway quantification of turbine materials in sCO2 as selection is crucial to successfully and economically operate new plants. This requires degradation assessment in representative environments simulating the Allam cycle. Laboratory tests were conducted on a first stage turbine blade alloy, CM247, with either an environmentally resistant coating or bond coat/thermal barrier coat at one atmosphere and 800°C, with potential exposure including (O2, H2O, N2, SO2) for up to 1000 h. Weight change and metallographic measurements tracked scale development. Scanning electron microscopy/energy dispersive X-ray spectroscopy studied scales and internal precipitates. Locations of contaminant element in the CO2-rich environment were investigated.

Methylene Blue Penetration of Resin Infiltration and Resin Sealant in Artificial White-Spot Lesions.

This study determined the potency of resin infiltrations and resin sealant in impeding microleakage on artificial white-spot lesions (AWL) by methylene blue penetration. Eighty AWL specimens were randomly separated into two groups for water storage for 24 hours (groups 1-4) and 20,000 cycles of thermocycling (TC) (groups 5-8). Each group was then separated into four subgroups (n = 10) based on the AWL surface treatments: (1) no Tx, (2) treated with resin infiltration (ICON, DMG, Hamburg, Germany), (3) treated with resin infiltration (Surface pre-reacted glass-ionomer (S-PRG) barrier coat, SHOFU, Kyoto, Japan), (4) treated with resin sealant (Clinpro sealant, 3M ESPE, Minnesota, United States). Nail varnish was covered to all samples, with the exception of a 4 × 4 mm2 patch on the buccal measurement region, which was subsequently submerged in a 2% methylene blue solution and cut into buccolingual sections. Stereomicroscope measurements were used to calculate methylene blue penetration scores. The Kruskal-Wallis test and the Bonferroni post-hoc correction were performed to evaluate the data. Application of resin infiltrants and resin sealant reduced microleakage in AWL by methylene penetration both before and after thermal cycling. In addition, group 6 (ICON + TC) and group 7 (S-PRG + TC) had a significantly different value from group 8 (sealant + TC). Both the resin infiltration approach and the resin sealant seem to help seal AWL and might perhaps offer long-term defense against microleakage in AWL caused by methylene blue penetration. The greatest sealing and defense for microleakage in AWL were demonstrated by the resin infiltrations.

Silver Diamine Fluoride versus Bioactive Giomer Light-Curing Varnish: An In Vitro Study on Caries Arrest

Objective To compare the capacity of silver diamine fluoride (30%) and the bioactive giomer light-curing varnish for arresting ICDAS score 5 non-retentive caries lesions. Material and Methods An in vitro analytical study was conducted using 36 healthy primary teeth, in which a cavity was created, divided into 3 groups: control (distilled and deionized water), giomer-based light-curing varnish – Barrier Coat, and Silver Diamine Fluoride 30% – Cariestop (SDF). The samples were analyzed for mineral loss as measured by surface microhardness (SMH).The Knoop microhardness test was performed using the HVS-1000 microhardness tester. The data were compared by two-way analysis of variance – treatment and time (before and after treatment) followed by Tukey’s post-test. The significance level adopted in all analyzes was 5%. Results The specimens treated with giomer showed higher SMH compared to the untreated group but were similar to those of the SDF group. The SDF group, on the other hand, showed no statistically significant difference from the control group (p=0.010). Conclusion The giomer varnish had a remineralizing effect on artificial dentinal caries.

Protective Effects of GIC and S-PRG Filler Restoratives on Demineralization of Bovine Enamel in Lactic Acid Solution

This study was aimed at investigating the protective effects of glass ionomer cement (GIC) and surface pre-reacted glass ionomer (S-PRG) fillers used as dental restorative materials on demineralization of bovine enamel. GlasIonomer FX ULTRA (FXU), Fuji IX GP Extra (FIXE), CAREDYNE RESTORE (CDR) were used as GICs. PRG Barrier Coat (BC) was used as the S-PRG filler. They were incubated in a lactic acid solution (pH = 4.0) for six days at a temperature of 37 °C. The mineral was etched from the enamel surface, and a large number of Ca and P ions were detected in solution. The Al, F, Na, Sr, and Sr ions were released in GICs and S-RPG fillers. The Zn ion was released only in CDR and the B ion was released only in BC. The presence of apparent enamel prism peripheries was observed after six days of treatment for the group containing only enamel blocks. pH values for the FXU, FIXE, CDR, BC, and enamel block groups after six days were 6.5, 6.6, 6.7, 5.9, and 5.1, respectively. Therefore, the observed pH neutralization effect suppressed progression of caries due to the release of several ions from the restoratives.

Metal contact sites: a hidden localization for nail varnish allergy?

It is thought that many people with nickel dermatitis use nail varnish as a barrier coat on nickel-containing metals; however, nail varnish allergy at sites in contact with such coated has only been documented once previously, to our knowledge. The aim of this study was to search for a possible link between nail varnish and metal allergy. In total, 1607 consecutively patch-tested patients were enrolled; 16 (1%) of these had nail varnish allergy, located mainly on the eyelids. Eight also had nickel allergy. Six of these eight had successfully used protective nail varnish on metals until subsequent development of 'failure of protection' even before the eyelid eczema developed. Sites in contact with metal might be a hidden and even initial localization for nail varnish allergy. 'Failure of protection' after a successful protective period despite renewing nail varnish coatings should raise suspicion of sensitization to the nail varnish itself. Future studies should focus on the incidence of allergic contact dermatitis and primary sensitization from nail varnish used as a barrier against nickel dermatitis.

Improved barrier properties of double dispersion coated liner

A dispersion coating formula that can be applied by conventional coating techniques and with satisfactory barrier properties has been developed. This formulation uses recyclable materials and is a cost-competitive replacement for wax-based barrier coatings. The water vapour transmission rate (WVTR) has been measured at both low and high humidity. At low humidity (50% R.H., 23 ° C) the barrier coating shows a WVTR of ≈ 40 g/(m 2 day −1) for a single coat and ≈ 20 g/(m 2 day −1) for a double coat at a total coat weight of 12 g/m 2. A dual coating consisting of one barrier coat and one pigmented top coat meets the industrial criteria of a WVTR < 50 g/(m 2 day −1) at high humidity (95% R.H., 3.5 ° C). This coating combination has acceptable print quality. The mechanosorptive creep of the dispersion coated corrugated board was also reduced significantly, particularly at high and variable relative humidity. The new coating therefore creates the opportunity to save fibre, as well as transport fuel, by manufacturing lighter weight boxes that maintain performance under the cyclic humidity conditions commonly encountered in goods distribution chains, particularly in the horticultural industry.