Resin Layer Research Articles

Preparation and Characterization of Sandwich Structured Materials with Interesting Insulation and Fire Resistance

A cellular material in the form of 3-layered sandwich structure material was prepared via sole use of mechanical stirring without any use of a foaming agent, while Tween-80 was employed as a foam stabilizer via a developed in-situ mold casting. The resulting structure displayed a good appearance with no visual defects. The 3-layered composition of the sandwish structure, “nonporous resin layer-porous foam layer-nonporous resin layer”, was examined in terms of the microstructure, density & density distribution, pulverization ratio, mechanical strength, insulation and flame retardant performance. It was indicated from the results that the bonding between the resin layer and foam layer was tight, while the tensile rupture always occurred in the porous layer. Also, the density of the sandwich structure material was symmetrical with “saddle” distribution, and a uniform density for any given layer. The increase in the density at the interface layer provided a good interpretation for the tensile rupture never occurred at the interface. The brittleness resistance of the developed material was significantly improved, and the pulverization ratio was sharply decreased from 9.93% to 0.31%. The material acquired a thermal conductivity and limiting oxygen index (LOI) of 0.0241 W/m ⋅ K and 29.92%, respectively, indicating potential use of such materials broadly in fields of insulation and flame retardancy.

Far-End Crosstalk Modeling and Prediction for Stripline With Inhomogeneous Dielectric Layers (IDLs)

Far-end crosstalk (FEXT) is a critical factor that limits signal integrity performance in high-speed systems. The FEXT level is sensitive to the dielectric inhomogeneity of the stripline in fabricated printed circuit boards (PCB). The dielectric of the stripline is manufactured with multiple inhomogeneous dielectric layers (IDLs) of various resin and glass fiber bundles. A marginal difference in the dielectric permittivity of the IDLs can lead to a significant change FEXT level. In this paper, a practical FEXT modeling methodology for striplines is proposed by introducing the extraction method for the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{\bm{\varepsilon }}}_{\bm{r}}$</tex-math></inline-formula> of IDLs. The new stripline model is constructed with three IDLs comprised of core, prepreg, and resin pocket, to improve the model accuracy. With the cross-sectional geometry and measured S-parameters of the coupled striplines, the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\bm{\ }}{{\bm{\varepsilon }}}_{\bm{r}}$</tex-math></inline-formula> of IDLs can be extracted. In addition, an analytical model to predict the FEXT polarity and magnitude of the stripline caused by the inhomogeneity is proposed targeted for pre-layout application. The proposed models have been verified using measurement. The proposed models can provide useful analysis methodology and design guidelines to mitigate the FEXT level in high-speed systems, especially for high-volume PCB tests in the pre-layout and post-layout stages.

Overview: Application of Resin Waterproof Adhesive Materials in Bridge Deck Pavement in China

To further promote the research and application of resin type waterproof adhesive layer materials, the types, relevant specifications, and research trends of resin type waterproof adhesive layer in China are comprehensively investigated. The performance evaluation indicators, performance requirement, and requirements in different specifications are systematically analyzed, and the key performance evaluation indicators are recommended. The basic properties of common resin type waterproof adhesive layer materials are studied, and the bonding properties of different resin waterproof adhesive layers were compared and evaluated. The results showed that pull‐out strength, shear strength, tensile strength, elongation at break, low temperature flexibility, and impermeability are the key performance evaluation indicators of resin waterproof adhesive layer. The tensile property, corrosion resistance, and water impermeability of resin type waterproof adhesive layer material are good, the flexibility of epoxy resin type waterproof adhesive layer material is poor, and the flexibility of methyl methacrylate (MMA) waterproof adhesive layer material is good. The bonding performance of the epoxy resin waterproof adhesive layer is better than that of the MMA. As the temperature rises, the bonding performance of the two waterproof adhesive layers is significantly reduced. At 60°C, the average pull‐out strengths of the epoxy resin and MMA waterproof adhesive layer were 1.83 MPa and 1.47 MPa, respectively.

Vol4 num4-18 Epoxy resins used in rollers for the paper manufacturing with improve mechanic properties, conductivity and roughness

Big rollers are used in the paper manufacturing industry, they are composed of layers of different materials (metallic core, polyurethane and composite with epoxy resin between others). The company TECNOCAUCHO is dedicated to the manufacturing of these rollers and towether with AIMPLAS have modified two epoxy resins that are used in two rollers (guide and calendering). In both cases the epoxy resin layer was the weak point of the rollers, consequently the mechanic properties of the resin were improved in order to extend the useful life of each roller and also the conductivity of the guide roller and the roughness and brightness of the calendering roller were improved. Currently, a epoxy resin with the improved properties achieved in this paper is not available on the market. Guide roller: mechanic properties of the epoxy resin were improved 7,7% compared to original comercial resin through nanofiller addition. Besides, resistivity values below 100 Ωm (company&acute;s target value) were achieved, minimizing the sparks generation. Calendering roller: mechanic properties were improved to 18,6% (tensile strenght at 130&ordm;C), brightness and roughness (Rz below to 0,2 microns, company&acute;s target value) through nanofillers addition, improving significantly the superficial properties of the paper.

Evaluation of mechanical properties of CFRP modeled by FDM

Knee joint diseases have been increasing in recent years due to the aging of society and the increase in the sports population. Knee braces used in treatment play a role in immobilizing and stabilizing the knee joint and reducing the direct burden on the knee joint. Therefore, the development of knee braces using CFRP material by fused deposition modeling (FDM), one of the additive manufacturing (AM) methods, is expected. The application and development of CFRP for knee orthoses requires safe design that considers the weakest points in terms of the shape of the various parts used in the orthoses and the walking motion. However, the mechanical properties of CFRP materials using FDM have not been clarified. In this study, the effects of carbon fiber content and orientation on the flexural strength of FDM-molded CFRP were investigated. 4-point flexural strength tests revealed that the carbon fiber layer was distributed throughout the entire structure, and that the higher the fiber content, the higher the strength. Therefore, it is suggested that an even arrangement of the fiber and resin layers increases the bending strength.

Fluorescence Lifetime Phasor Analysis and Raman Spectroscopy of Pigmented Organic Binders and Coatings Used in Artworks

Fluorescence analysis of materials used as binders and coatings in artworks is often hampered by numerous factors, leading to uncertainties in data interpretation. Fluorescence lifetime (FL) measurements enable improvement of the specificity with respect to steady-state measurements by resolving the decay dynamics of the fluorophore emissions. In this work, layers of natural resin, oil, and wax—in pure form, pigmented, in mixtures, and spread on different substrates—were analyzed using a compact, portable, fiber-based FL instrument. FL data were processed via the phasor method and integrated with Raman spectroscopy to obtain complementary chemical information on the different substances. It was observed that the τ-phase of the mixtures is affected by both the pigments and the dispersing medium, and that the presence of the metal substrate contributes to changes in the FL of mixtures. The results obtained with our portable FL system combined with Raman spectroscopy pave the way for a systematic study of a larger number of materials for future in situ applications on works of art.

Excellent Li/Garnet Interface Wettability Achieved by Porous Hard Carbon Layer for Solid State Li Metal Battery.

Garnet-type Li6.4 La3 Zr1.4 Ta0.6 O12 (LLZTO) electrolyte is considered as a promising solid electrolyte because of its relatively high ionic conductivity and excellent electrochemical stability. The surface contamination layer and poor Li/LLZTO interface contact cause large interfacial resistance and quick Li dendrite growth. In this paper, a porous hard carbon layer is introduced by the carbonization of a mixed layer of phenolic resin and polyvinyl butyral on the LLZTO surface to improve Li/garnet interfacial wettability. The multi-level pore structure of the hard carbon interlayer provides capillary force and large specific surface area, which, together with the chemical activity of the carbon material with Li, promote the molten Li infiltration with garnet electrolyte. The Li/LLZTO interface delivers a low interfacial resistance of 4.7 Ω∙cm2 at 40 °C and a higher critical current density, which can achieve stable Li+ conduction for over 800 h under current densities of 0.1 and 0.2 mA∙cm-2 . The solid-state battery coupled with Li and LiFePO4 exhibits excellent rate and cycling performance, demonstrating the application feasibility of the hard carbon interlayer for a solid state Li metal battery.

Shear bond strength of orthodontic tubes bonded directly with composite resin reinforcement on the enamel surface

To evaluate the shear bond strength and the fracture type of orthodontic tubes bonded directly with composite resin throughout the enamel surface. 30 bovine teeth were cut into 3 slices with 5 mm each and embedded in PVC pipes with acrylic resin exposing the buccal face. Subsequently, the teeth were submitted to conventional bonding techniques. Natural Ortho resin was applied for direct bonding of Edgewise Standard orthodontic tubes (Morelli®) and light-cured for 20s. A different viscosity resin was chosen and light-cured for 40s to reinforce the tube surface. The samples were divided into the following groups: Orthodontic tube with direct bonding without reinforcement (CONTROL), Tube with Natural Ortho resin + Reinforcement (NO + NO), Tube with Natural Ortho resin + Reinforcement with Flow resin (NO + FL). These were submitted to shear bond strength; immediate and 1-year aging fracture analysis after simulated through thermocycling. In the shear bond strength test, the group of orthodontic tubes that were directly bonded with Natural Ortho resin and reinforced (NO + NO) showed greater strength results after 24 hours and 1 year with values of (p=0.0225) and (p=0.0273). It was statistically differentto the NO + FL and CONTROL reinforced groups. In the fracture analysis, the NO +NO group was classified immediately as composite cohesive, and mixed failure after aging by thermocycling. The addition of a composite resin layer on the surface of the directly bonded orthodontic tube improved bond strength. The reinforcement must be carried out in regular consistency and the use of Flow resin is not indicated.

Controlling the bidirectional chemical environments for high-performance Y@silicalite-1 core-shell composites in shape selective desulfurization

• Alkali and Cu 2+ are used to tune the structure and increase active sites of Y zeolite. • Resin layer and EDA can provide stable external environment for silicalite-1 shell. • Selective-adsorption achieved 75.58 mg/g, double of 37.1 reported previously. • Extraction before calcination kept 92% desulfurization rate after 6 regeneration cycles. A high-performance Y@silicalite-1 core–shell composite for shape- selective adsorption desulfurization was synthesized by controlling the bidirectional chemical environments via a resin interlayer between Y zeolite core and silicalite-1 shell. In this process, the alkali treatment, Cu 2+ ion-exchange, Cu 2+ equal volume impregnation, resin coating and ethylenediamine modification were applied to work collaboratively for a high shape selectivity and high sulfur adsorption capacity. Results showed that alkali treatment for 2 h, TEOS:Y = 4, Y:3-aminophenol = 1:1, Y: EDA = 1:1 and 550 °C calcination could endow the synthesized core–shell structured composite with a high-performance in shape-selective adsorption desulfurization of DMDS from MTBE solution with a maximum sulfur adsorption capacity of 75.58 mg s /g adsorbents , which was more than double of the best DMDS sulfur adsorption capacity from MTBE (37.07 mg s /g adsorbents ) reported previously. The adsorption kinetic and isotherm analysis indicated that the adsorption of DMDS on Y zeolites was monolayer-chemisorption process, and the corresponding theoretical saturated adsorption capacity could reach up to 84.6 mg s /g adsorbents . The regeneration capability can be effectively improved by ethanol extraction before calcination, retaining a high desulfurization rate level at more than 92% even after 6 cycles.

Modeling and Analysis of Silver-Sintered Molybdenum Packaging for SiC Power Modules With Improved Lifetime and Temperature Range

With the application of wide bandgap devices, the packaging technology of power modules is faced with elevated challenges. This paper proposes a new packaging concept for silicon carbide power modules. The main objective is to improve the lifetime and temperature range, while the proposed packaging also has the potential to reduce stray inductance and simplify the fabrication process. In the proposed concept, sintered nano-silver is selected as the die bonding. The conventional direct-bonded-copper substrate is replaced by a molybdenum layer and a bismaleimide triazine resin layer which has a low thermal expansion coefficient. A steady-state thermal-mechanical analysis is conducted to verify the material selection. Furthermore, a transient thermal-mechanical analysis based on JEDEC temperature cycling methods is carried out, whose results are applied in the Coffin-Manson lifetime model to evaluate the advantages of the proposed Silver-Sintered Molybdenum Packaging. The results demonstrated that the proposed packaging technology could improve the lifetime by over 1000 times and increase the maximum operating temperature by nearly 3 times. Finally, a feasible process of sintering SiC chips on molybdenum substrates is proposed, which achieves a uniform and low porosity bonding.

Do universal adhesives provide the benefits from double-application or an extra bonding layer in composite repair?

This study aimed to determine whether the application of extra hydrophobic resin (EHR) or double layer (DL) improves microtensile bond strength (μTBS) of two universal adhesives to composite resin. Composite blocks were fabricated and exposed to thermal cycles. The specimens were horizontally sectioned into two halves. Scotch Bond Universal (SBU) and Clearfil S3 Bond Universal (CSBU) were applied to the ground composite surface according to the manufacturers' instructions, or with DL application or EHR application. The repair composite was incrementally placed to bonded planes. Composite sticks were achieved and tensed with a universal testing machine, followed by examining the fracture surfaces by a scanning electron microscope. Data were evaluated by Weibull analysis (shape and scale [σθ and σ0.10 ] parameters) using the maximum likelihood method. The σθ and σ0.10 , respectively, estimate strength at 63.2 and 10% probability of failure. Shape parameter values showed significant differences among treatments. DL application of CSBU did not affect μTBS values at σθ of failure but caused to decrease μTBS values at σ0.10 of failure. DL application of SBU reduced μTBS values at σθ of failure. DL or EHR coating did not improve μTBS of SBU. EHR application increased μTBS of CSBU, whereas DL application did not benefit.

Extracted quartz as efficient natural demulsifier for crude oil-water emulsions: Effect of monovalent/divalent salts, pH and modeling study

Smooth running of upstream and downstream operations is very key for the successful hydrocarbon production and delivery to the end users. Investigated in this study is the application of quartz particles as naturally occurring demulsifiers for demulsification activity in the petroleum industry. Effect of monovalent (NaCl and KCl) and divalent (MgSO4.7H2O, CaCO3, CaCl2 and MgCl2.6H2O) salts on the effectiveness of quartz (3 wt%) to displace the natural emulsifiers and separate water and crude oil were assessed at various temperatures (45–75 °C). Also, evaluated is the tolerance of quartz particles to pH change during demulsification at 75 °C. Modeling was applied to elucidate the measured demulsification of the produced emulsions. Experimental outcomes revealed that quartz demulsification efficiencies were slightly higher in the crude oil emulsions produced from brine containing NaCl salt as compared to the emulsions obtained from KCl salt across the various temperatures examined. Water removal by quartz particles at equilibrium for emulsions containing NaCl and KCl salts were estimated to be 98% and 95.8%, respectively, while 93% water removal was achieved in emulsions produced from either CaCl2 or MgCl2.6H2O divalent salts at 75 °C. However, MgSO4.7H2O and CaCO3 divalent salts impacted swift water/crude oil separation in the produced emulsions within a very short period. Quartz demulsification efficiency was great in both acidic and alkaline media; however, its performance was much more excellent in the alkaline medium, especially at pH 10. Rheological determinations and optical microscopic analysis affirmed the workability of quartz particles to distort the asphaltenes and resin layers. Sequential minimal optimization (SMO) algorithm tool in machine learning was applied to predict the experimentally determined quartz demulsification efficiencies with significant matches and correlations.

Core Cracking in Advanced Organic Substrates Due to Free Edge Effect at Cold Temperatures

Advanced FPGAs utilizing substrates with thick organic core showed substrate core cracking after thermal cycling. These substrates are laminate structures with a core made from stacked layers of glass fiber and resin with routing layers made of copper and dielectric build-up polymer. This type of cracking typically occurs on the glass fiber-resin interface, can penetrate several millimeters and across thru-vias to cause electrical failure, and was found on several test vehicles, four of which are detailed here. This work observed numerous examples to identify the characteristics of the cracking and notes the best observation practices. We hypothesize this cracking is due to free edge effect at cold temperature. Since the free edge cannot have normal stress, a large out-of-plane stress exists at the edge and concentrates at the corner. Models were built to study the effects of various package parameters on the failure mode. The primary contributions to the free edge effect are the low-CTE glass fiber, the high-CTE resin, and the high-CTE build-up layers. The trend toward lower CTE substrates has demanded lower CTE glass fiber material, which exacerbates this problem. Increasing complexity of routing demands additional layers, which also increases the out-of-plane stress at the corner. Other less significant factors that increase the stress include lower resin CTE, higher build-up CTE, and decreasing core thickness. Thru-via placement and dicing optimization had small impact and substrate had negligible impact.

Physical and Mechanical Properties of Natural Fiber Polyester Laminate Composites

The utilization of natural fibers as reinforcing composites has been widely used. Indonesia has natural fibers abundantly such as ijuk fiber (Arenga pinnata), sisal fiber (Agave Sisalana) and coconut fiber (Cocos Nucifera). Random orientation application of the fiber in composites affected to the lower properties. Therefore, the particular orientation of fibres wereapplied in manufacturing of composite by laminating the short fiber with Polyurethane (PU) adhesive. The size and moisture content (MC) of fiber were 14-15 cm and +10%, respectively. The resin content of PU was 5% by weight of the laminate sheet. The mixture of fibers and PU adhesive was cold pressed for 5 minutes with a thickness of 0.5-1 mm. The laminate sheet of PU-adhesive fibers then mixed with unsaturated polyester resin layer by layer. The fiber laminate composition of composite was varieted such as 1, 2 and 3 layers. The hand layup method was used in the manufacturing of the composite. The physical and mechanical testing like density, moisture content, water absorption, thickness swelling, flexural test (adapt to ASTM D 790 standard) and tensile test (adapt to ASTM D 638 standard) were carried out. In additionmorphological analyses were investigated on composite samples. The results research showed that the net density of polyester, ijuk fiber sheet, sisal fiber sheet, and coconut fiber sheet were 1.21, 0.9, 0.53 and 0.22 g/cm3. The range of composite density was 0.99-1.15 g/cm3. The single layer composite had lower thickness swelling and water absorption than those of the three layers composite. The highest tensile strength of three layers of sisal fiber composite was higher (33.84 MPa) than that of the three layers of coconut fiber composite (12.04 MPa). The flexural strength of double layers composite from fiber sisal was higher (63.16 MPa) than that of three layers coconut fiber composite (28.65 MPa).

An experimental study of impulse-current-induced mechanical effects on laminated carbon fibre-reinforced polymer composites

Lightning strike damage has become a primary issue limiting the extensive application of carbon fibre-reinforced polymer (CFRP) composites in the aerospace field. A detailed understanding of the physical interactions involved in the lightning strike process is still lacking, especially regarding the lightning-induced mechanical effects that potentially contribute to fracture and ply delamination in CFRP structures. This paper presents research on shock wave pressure induced by impulse currents on CFRP laminates. A novel method that exploits a polyvinylidene fluoride (PVDF) piezoelectric sensor was developed to directly measure the pressure induced by arc channel expansion. The influences of discharge polarity, strike distance and surface condition on the shock wave pressure were investigated. The results showed that the shock wave pressure produced by negative discharge was greater than that produced by positive discharge, the difference between which was reasonably explained based on the polarity effect concept. Increases in current amplitude and strike distance both contributed to larger measured pressures. A woven copper mesh protection could diminish the shock wave pressure to some extent, while an additional insulating epoxy resin layer enhanced it. Analysis results demonstrated that the pressure imposed on the laminated samples was related to the energy injected into the arc channel. In addition, the energy consumed by vaporized materials at the interface between the arc root and sample was defined as another source of shock wave pressure. The presence of an insulating layer confined the diffusion of the plasma channel at the arc root, as confirmed by high-speed imaging observations.

Process-induced strains measurements through a multi-axial characterization during the entire curing cycle of an interlayer toughened Carbon/Epoxy prepreg

High dimensional accuracy of thermoset composite parts is a challenging issue for manufacturers in the aeronautical industry. A deep understanding of the cure behavior is required in order to prevent internal stresses generation as being responsible of shape deformations. However, the specific challenge of experimental investigations is to cover all of the stages of the cure process including the pre-gelation region. In this paper, the characterization of the process-induced strains throughout the cure is based on using a laboratory scale bench named as PvT-HADDOC. Tests were performed on a unidirectional interlayer toughened aerospace prepreg. The device enables the measurements of the induced strains simultaneously along the out-of-plane and the in-plane directions. The consolidation of the uncured material is captured. The measured coefficients of thermal expansion are proved to be higher through the thickness direction in the liquid and cured states. The chemical shrinkage is measured before and after gelation along both transverse directions. The orthotropic behavior of IMA/M21 system is attributed to the presence of interleaf layers of resin within the prepreg plies.

A Double-Layer Epoxy and Polyaniline/Graphene Oxide Composite Coating for Corrosion Protection of Carbon Steel Immersed in Seawater

Offshore pipelines transport the produced hydrocarbon from the upstream production well to the downstream hydrocarbon separation facilities. Offshore oil and gas pipelines are still the safest way of transporting hydrocarbon, as evidenced by significant low failure rates in contrast with highway transportation, railroad, and ships, yet. The failures do occur and often with catastrophic results, especially to the marine eco-system. There are several origins of pipeline failures, but corrosion is the main one. Coatings are always used to control external corrosion of pipelines, in combination with impressed cathodic protection. However, the development of new coatings has always been an ongoing process. Recently, non-conducting epoxy coatings combined with conducting polymers (CPs) have been used to protect metals from corrosion [1]. Epoxy coatings are often used for corrosion prevention because of their exceptional mechanical, barrier and chemical properties [2-4]. CPs coatings have exhibited promising corrosion inhibition performance of metal substrates because they are environmentally stable, eco-friendly, non-toxic, and adhere firmly to the metal surface [5].In the present work, we developed and applied a double-layer coating on carbon steel (CS) to overcome the limitation of polyaniline/graphene oxide (PANI/GO) composites during an extended emersion time in the corrosive environment. We first synthesized polyaniline (PANI) coating incorporating a single-layer-GO directly on the carbon steel substrate by an electrochemical deposition method (inner layer), which was then followed by the application of a second (outer/top) layer of commercial pure neat epoxy resin. The corrosion resistance studies revealed that the two-layer PANI/GO/epoxy coating offered a significantly better long-term protection towards corrosion of the CS surface than the two-layer PANI/epoxy and, especially, than the single-layer epoxy coating.The coatings’ surface morphology was studied by field-emission scanning electron microscopy. The thickness mapping of the coatings was evaluated by a profilometer. The coatings’ surface wettability was also determined. The electrochemical/corrosion measurements were carried out in an aqueous 3.5 wt.% NaCl. Electrochemical impedance spectroscopy (EIS) and Tafel polarization were used to investigate the corrosion resistance of the coated and uncoated samples. CS samples coated with only PANI, or PANI/GO could not be instigated using Tafel and EIS techniques due to the samples’ relatively good electrical conductivity. Before each Tafel and EIS run, the samples were conditioned at open-circuit potential (OCP) for 1 hour. EIS measurements were performed at OCP in the frequency range between 10 mHz and 50 kHz applying a ±10 mV alternating voltage amplitude. Tafel polarization curves were recorded by anodically polarizing the samples from -200 mV to +200 mV vs. OCP at a scan rate of 1 mV s-1. All potentials in this paper are referred to SCE. All the measurements were performed at 22±1oC.Profilometry measurements revealed that the thickness of the PANI and PANI/GO coatings was 4.84±0.12 mm, while the epoxy coating was substantially thicker, 20.6±0.2 mm, and the double layers coating thickness was 24.9±0.14 mm. Our corrosion resistance results indicate the application of the epoxy coating resulted in a corrosion current decrease by almost two orders of magnitude, while the addition of the thin PANI sub-layer contributed to the further reduction by ca. two orders of magnitude. A surprising finding was that incorporating just 0.01 wt.% of GO into the PANI matrix resulted in a significant additional decrease in the corrosion current of almost two orders of magnitude. Long-term measurements (60 days, Figure 1) revealed that the corrosion resistance of the PANI/GO-epoxy coating remained stable. The PANI-epoxy coating started failing after ca. 37 days, while the resistance of the single-layer epoxy coating was substantially lower and decreased first after ca. 4 days of immersion, and then again started decreasing after ca. 19 days of immersion. The sustained high impedance value for the entire immersion time demonstrates excellent barrier performance of the double-layer PANI/GO-epoxy coating.[1] D.W. DeBerry, Journal of the Electrochemical society, 132 (1985) 1022.[2] V. Mišković-Stanković, J. Zotović, Z. Kačarević-Popović, M.D. Maksimović, Electrochimica acta, 44 (1999) 4269-4277.[3] Y. Wei, L. Zhang, W. Ke, Corrosion science, 49 (2007) 287-302.[4] Y.-X. Lan, C.W. Weng, M.M. Ahmed, K.-H. Luo, W.-F. Ji, W.-R. Liu, J.-M. Yeh, Materials Chemistry and Physics, 264 (2021) 124446.[5] S. Kim, T.-H. Le, C.S. Park, G. Park, K.H. Kim, S. Kim, O.S. Kwon, G.T. Lim, H. Yoon, Scientific reports, 7 (2017) 1-9. Figure 1

A Robust Superhydrophobic Perfluoropolysiloxane and Self-doped Polyaniline/Epoxy Resin Composite Coating with Excellent Performance

Abstract A robust superhydrophobic perfluoropolysiloxane and self-doped polyaniline/epoxy resin composite coating (EPAN-RA-POS) was prepared. The structure is composed of the internal self-doped polyaniline/epoxy resin layer and the outer superhydrophobic perfluoropolysiloxane layer. The contact angle (CA) and sliding angle (SA) of EPAN-RA-POS are 165.0° ± 1.5 and 1.2° ± 0.7, respectively, the protection efficiency and immersion durability of EPAN-RA-POS reach 99.99% and 408 h, the superhydrophobicity is only lost after 330 peeling experiments.

Research on suppressing brittle fracture and implementing ductile mode cutting for improving surface quality at silicon wafers manufacturing

Single crystal silicon is an important basic material used to manufacture electronic and photovoltaic devices. Ductile mode of diamond wire sawing is a promising method for silicon wafering in order to produce wafers with minimal surface damage. To achieve ductile mode, the correct applying of cutting parameters and careful wire design is necessary. This study investigates the scratching of monocrystalline silicon by the abrasive particles of different geometry, which simulates the material removal process in diamond wire sawing. Diamonds, crushed and spherical tungsten carbide (WC) particles served as abrasives. Experiments show that spherical abrasives enhance ductile mode cutting significantly decreasing brittle damage when compared to irregular shape particles. Spherical WC particles permit to increase the critical load and critical cut depth of ductile-to-brittle transition from 5 to 10 times. The depth of the damaged subsurface layer decreased from 5 µm to 0.2 µm due to the absence of brittle cracks. A uniform regular distribution and appropriate suitable density of abrasive particles is obligatory for cracking reduction. For that, the method of diamond particles uniform deposition with the controlled density by a polymer binder combining high modulus and adhesive capacity with good flexibility was elaborated. The method includes preliminary diamond particles fixation on a thin resin layer providing high uniformity and subsequent strong fixation by a thicker resin layer. The research on ovalization of diamond particles was performed for smoothening cutting edges. The method is based on the activation of the graphitization process at sharp edges of particles under the action of metal salts at increased temperatures.

Pengaruh Konsentrasi Resin dan Suhu Pemanas Awetan pada Penyempurnaan Lipatan Permanen Kain Poliester 100%

Permanent press by using resin will increase the resistance of the desired material properties. The refinement process to obtain permanent fold properties in polyester fibers is obtained by forming a polymer resin layer on the surface of the fabric. The more resin used, the less the ability of the fabric to come back from the crease, so the permanent crease finish will be more permanent.&#x0D; However, with more and more resin polymerizing on the surface, the fabric will be stiffer and can reduce the tensile strength of the fiber, the occurrence of the resin polymerization process is influenced by the temperature of the preserved heating when the temperature is less then the resin is not formed perfectly or if the temperature is too high it can cause damage to the fiber. This test was carried out on 100% polyester fabric with variations in the concentration of melamine formaldehyde resin 40 g/l, 50 g/l, 60 g/l, 70 g/l and variations in the curing temperature of 1600C, 1700C, 1800C, 1900C. Tests carried out include re-testing of the folds and tensile strength of the fabric. The results showed that the optimum conditions achieved in this experiment were at a concentration of melamine formaldehyde resin of 60 g/l with a preserved heating temperature of 1700C, a low folding angle value of 740 was obtained with a tensile strength value that above the minimal standards, namely the warp 75.7 Kg and weft 22.7 Kg.