Methodology of the selection of effective dipping and control over the filling depth of open-textured construction materials

It is determined that for the combination of the dipping process with the ultrasound control it is necessary to carry out the optimization of the filling speed and the precision of control over the dipping depth, to determine the optimum frequency of the ultrasound emission which satisfies the speed and the dipping measurement precision of the sample with the hydrophobic agent. On the basis of the performed multiobjective optimization, experimental results for the dipping and the control over the dipping stage of porous materials by the solution in the uniform acoustic field alignment charts are received for the selection of the rational frequency of ultrasound fluctuations which allow regulating and/or optimizing dipping and control processes over the material filling depth subject to customer tasks. The selection methodology of effective values of parameters of the acoustic field providing the combination of filling processes and the control over the depth of the dipped material filling is well-reasoned.

Plywood Made from Plasma-Treated Veneers: Investigation of Performance Differences between Plasma-Pretreated and Untreated Beech Veneers at Comparable Melamine Resin Load

In this study, the dimensional stability and mechanical properties of plywood made from untreated and plasma-pretreated beech veneers were compared. The wood veneers used (native and thermally modified) were impregnated with melamine resin in a simple dipping process prior to plywood production. The duration of the impregnation process was adjusted to give the same melamine resin loading for the different veneer types, with the plasma-pretreated veneers requiring only a fraction of the impregnation time compared with non-plasma-pretreated veneers. With comparable melamine loading, testing of the mechanical properties of the plywood for the different specimen collectives showed significant differences in some cases with respect to compressive strength, bending strength and tensile strength (with the associated moduli of elasticity). For example, it was shown that plywood made from plasma-pretreated native beech veneers shows an increase in bending strength of about 8%, and from plasma-pretreated and thermally modified beech veneers, there is an increase of about 10% compared to the reference.

Influence of Different Wax Hardening Agents on Surface Roughness of Refractory Cast Investment Materials

Background: Phosphate-bonded investments produce a refractory cast model with rough surface and undesirable properties. Dental Surface hardening agents are then applied to refractory investment materials to enhance its properties. Purpose: compare and evaluate the effects of different dental cast hardening agents (Bees wax, Carnauba wax, and Ceresin wax) on surface roughness of refractory model investment material. Approach: 30 specimens were constructed from commercially available phosphate bonded investment material. Specimens were subjected to a roughness test before dipping in handing agents, then divided into three groups according to the type of wax in which they were dipped. (10 specimens for each type). Surface roughness test was done by a profilometer where three readings were taken for all the specimens' surfaces randomly. The mean was then extracted for the roughness values before and after dipping in waxes. Results: the mean and standard deviation were tabulated and statistically analyzed using students T- test. The roughness values were decreased after the specimens were dipped in waxes (P value < 0.001 HS highly significant). Conclusion: The dipping process with hardening agents has significantly improved the surface roughness of the specimens' investment materials.

Mold Flow Analysis of Motor Core Gluing with Viscous Flow Channels and Dipping Module

A motor core is formed by stacking iron sheets on top of each other. Traditionally, there are two stacking methods, riveting and welding, but these two methods will increase iron loss and reduce usage efficiency. The use of resin is the current developmental trend in the technology used to join iron sheets, which has advantages including lowering iron loss, smoothing magnetic circuits, and generating higher rigidity. The flow behavior of resin in gluing technology is very important because it affects the dipping of iron sheets and the stacking of iron sheets with resin. In this study, a set of analytical processes is proposed to predict the flow behavior of resin through the use of computer-aided engineering (CAE) tools. The research results are compared with the experimental results to verify the accuracy of the CAE tools in predicting resin flow. CAE tools can be used to predict results, modify modules for possible defects, and reduce the time and costs associated with experiments. The obtained simulation results showed that the filling trend was the same as that for the experimental results, where the error between the simulation results for the final dipping process and the target value was 0.6%. In addition, the position of air traps is also simulated in the dipping process.

Essential role of papillae flexibility in nectar capture by bees

Many bees possess a tongue resembling a brush composed of a central rod (glossa) covered by elongated papillae, which is dipped periodically into nectar to collect this primary source of energy. In vivo measurements show that the amount of nectar collected per lap remains essentially constant for sugar concentrations lower than 50% but drops significantly for a concentration around 70%. To understand this variation of the ingestion rate with the sugar content of nectar, we investigate the dynamics of fluid capture by Bombus terrestris as a model system. During the dipping process, the papillae, which initially adhere to the glossa, unfold when immersed in the nectar. Combining in vivo investigations, macroscopic experiments with flexible rods, and an elastoviscous theoretical model, we show that the capture mechanism is governed by the relaxation dynamics of the bent papillae, driven by their elastic recoil slowed down through viscous dissipation. At low sugar concentrations, the papillae completely open before the tongue retracts out of nectar and thus, fully contribute to the fluid capture. In contrast, at larger concentrations corresponding to the drop of the ingestion rate, the viscous dissipation strongly hinders the papillae opening, reducing considerably the amount of nectar captured. This study shows the crucial role of flexible papillae, whose aspect ratio determines the optimal nectar concentration, to understand quantitatively the capture of nectar by bees and how physics can shed some light on the degree of adaptation of a specific morphological trait.

Comprehensive study of the effect of hot-dipping process parameters on Sn-Sb coating properties for α-brass substrate

This study's main purpose is to achieve an optimal hot-dip coating condition of Sn-Sb for an α-brass alloy. Therefore, the hot-dipping parameters, including pre-flux lubricants, immersion temperature, time, and withdrawal speed were investigated. ZnCl2 and SnCl2 were used as pre-flux bath additives. The temperature of the immersion bath was selected to be in the range of 250-300 °C. Also, the exposing time and withdrawal speed of the specimens during the hot-dipping process were in the range of 10-60 sec and 254-1524 mm/min, respectively. Visual inspection of the coating revealed that by using SnCl2 as a pre-flux additive, high-quality smooth coating is achieved. According to the AFM result, the initial roughness value of the substrate was 450 nm. The coating's roughness value with SnCl2 and SnCl2+ZnCl2 pre-fluxes were in the range of 300-500 and 700-900 nm, respectively. Therefore, ZnCl2 pre-flux is associated with a rougher surface. Corrosion test analysis revealed that both coating condition with different pre-fluxes leads to increasing corrosion resistance however better improvement in corrosion behavior is accomplished by smooth coating surface. The quantitative analysis of the polarization curve revealed that the corrosion rate of the smooth coating is decreased 7-12.5 times in comparison with the substrate. According to the SEM analysis, the predominant phases which were appeared at the interface of the coating and substrate were Cu3Sn and Cu6Sn5. SEM analysis revealed that the Cu3Sn intermetallic compound was this first phase, which was promoted near to the substrate vicinity during the hot-dipping process.

Characterization of Interfacial Microstructure of Cast Iron Inserts Dipping in Aluminum Alloy Melt

Commercial vehicle pistons should have low thermal expansion and should be able to withstand deformation or mechanical stress. Aluminum alloys are suitable for pistons due to their light weight. However, as aluminum alloys have low strength and friction resistance, cast iron is added through the dipping process in order to increase the quality of pistons. However, the dipping process leads to defects such as defective bonding, void formation, and formation of an oxidation film at the junctions of the two materials due to differences in their properties, which adversely affects the impact resistance and mechanical strength of the product. A theoretical study on the metallurgical bond between the aluminum alloy and the cast iron insert in the piston was conducted to investigate the cause of the defects. The microstructure of the intermetallic bonding layer was observed using scanning electron microscopy and electron dispersive spectroscopy. In this study, defects were found in non-bonding and oxide films and several phases were generated corresponding to different parameters. It was found that processing time and temperature were the main causes of these defects.

Dipping-Press Coating Method for Retaining Transparency and Imparting Hydrophobicity Regardless of Plastic Substrate Type

Plastics are used in cover substrates for billboards, windows, large LED signboards, lighting devices, and solar panels because they are transparent and can be colored and shaped as desired. However, when plastic cover substrates installed in outdoor environments are constantly exposed to harsh conditions such as snow, rain, dust, and wind, their transparency deteriorates owing to watermarks and dust contamination. Herein, we investigated a simple dipping-press coating method that can impart hydrophobicity while maintaining the transparency, regardless of the plastic substrate type. A highly transparent and hydrophobic coating film was formed on a plastic substrate by a two-step process, as follows: (1) application of a polydimethylsiloxane–octadecylamine coating by a dipping process, and (2) embedding (1H,1H,2H,2H-heptadecafluorodec-1-yl) phosphonic acid–aluminum oxide nanoparticles by a thermal press process. The plastic substrates on which the highly transparent and hydrophobic coating film was formed showed 150° or higher hydrophobicity and 80% or higher visible light transparency. The coating method proposed herein can easily impart hydrophobicity and is compatible with any plastic substrate that must maintain prolonged transparency without contamination when exposed to adverse conditions.

Surface modification of PE/PET by two-step method with graphene and silver nanoparticles for enhanced electrical conductivity

Polyethylene/polyethylene terephthalate (PE/PET) nonwoven fabrics were first modified with a continuous graphene layer by using a dipping process, and then deposited with silver nanoparticles (AgNPs) by using magnetron sputtering, and that is a novel method called two-step method. Graphene/PE/PET (GPP) and AgNPs sputtered GPP (AGPP) were prepared to investigate the modification processes on the electrical conductivity of the nonwoven fabrics. The influence of the surface modification by silane coupling agent (KH-560) on the durability of conductive PE/PET composited fabrics is also studied. Surface morphology, chemical structure, thermal stability, electrical conductive and ultraviolet protection properties of the composite fabrics were investigated. The results indicated KH-560 treatment can obviously improve the interfacial adhesion between the graphene and PE/PET then contributes to the enhanced conductive durability of the composite fabrics. The combination of graphene and AgNPs provided more opportunities for the charge transfer paths of AGPP, leading to an improved conductive network and an increased electrical conductivity. In addition, graphene and AgNPs gave GPP and AGPP excellent thermal stability. The research exhibited the advantages of the two-step method, and also indicated AGPP has a promising application for the preparation of wearable electronics.

ANALYSIS AND MICROHARDNESS PROFILE OF HOT DIPPING COATING ON LOW-ALLOY STEEL

This research is an effort to understand the morphology of the coating produced during hot dipping process in pure zinc bath based on iron–zinc phase diagram. In this investigation, zinc coating on low-alloy steel AISI 4340 samples was applied by hot dipping method followed by an annealing process. Morphological characterizations of the steel surface layer were accomplished by optical microscopy (OM) and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectrometry (EDS). Results revealed that the coating is bonded to the steel surface through a sequence of Fe–Zn layers namely alpha ([Formula: see text], delta ([Formula: see text] and zeta ([Formula: see text] with uniform sloping hardness profile.