Solid Filler Research Articles

AA6082 to DX56-Steel Laser Brazing: Process Parameter–Intermetallic Formation Correlation

In the present study, laser-brazed AA6082 to DX56-galvanized steel joints were investigated to understand the influence of process parameters on joint strength in terms of intermetallic layer formation. 1.5-mm-thick sheet of aluminum alloy (AA6082-T6) and galvanized steel (DX56) sheet of 0.7 mm thickness were laser-brazed with 1.5-mm-diameter Al-12% Si solid filler wire. During laser brazing, laser power (4.6 kW) and wire feed rate (3.4 m/min) were kept constant with a varying laser scan speed of 3.5, 3, 2.5, 2, 1.5, and 1 m/min. Microstructure of brazed joint reveals epitaxial growth at the aluminum side and intermetallic layer formation at steel interface. Intermetallic layer formation was confirmed by EDS analysis and XRD study. Hardness profile showed hardness drop in filler region, and failure during tensile testing was initiated through the filler region near the steel interface. As per both experimental study and numerical analysis, it was observed that intermetallic layer thickness decreases with increasing brazing speed. Zn vaporization from galvanized steel interface also affected the joint strength. It was found that high laser scan speed or faster cooling rate can be chosen for suppressing intermetallic layer formation or at least decreasing the layer thickness which results in improved mechanical properties.

Evaluation of Filler Effects on the Dynamic Mechanical Behavior of HTPB-Elastomer Used as Binder in Exemplary Composite Formulations

This study aims to evaluate the dynamic mechanical properties of a binder, used in composite propellants, with increasing amount of different solid fillers. Dynamic Mechanical Analysis (DMA) is performed to determine the region of glassrubber transition temperature (Tg). Further parameters were obtained from the description of the loss factor curves (tanδ) with models based on exponentially modified Gauss (EMG) distribution function. Polyurethane binders employing the polyol HTPB and diisocyanate were filled with 20,40,and 60 mass-% of ammonium perchlorate (AP), aluminum (Al) or cyclotrimethylene trinitramine (RDX) particles, using fine and coarse mean sizes. A special turning device manufactured by Fraunhofer ICT was installed inside the curing oven in order to avoid sedimentation during curing. The cured composites were characterized by DMA in torsion mode from ‑100 °C to 70 °C. The good homogeneous distribution of fillers in the samples was evaluated by computational X-ray micro-tomography. The data on tanδ showed a complex structure describable at first with 2 overlapping peaks. The peak at lower temperatures is due to mobility of unrestricted binder parts (Tg unr) and the second broader peak at high temperature is due to mobility of restricted binder parts (Tg res). Results of tanδ, calculated areas of EMG curves and apparent activation energies of the distinct relaxation processes indicate that Al particles have higher interaction with HTPB-based polyurethane than AP and RDX. Probably Al is bonded to the binder network via isocyanate coupling with OH groups present in the surface. Ammonium perchlorate and cyclotrimethylene trinitramine particle sizes and its morphology influenced the viscoelastic properties. AP and RDX cause more changes in intensity of first peak of loss factor than Al. Increasing amount of these both particles enhances storage (G’) and loss (G”) shear moduli. As a whole tanδ intensity is lowered in the main peak and Al showed an intensity increase in the second apparent peak.

Comparative study of single and multi-layered packed-bed thermal energy storage systems for CSP plants

The Multi-layered Thermal Energy Storage (TES) tank consists of three regions–top and bottom part is packed with suitable Phase Change Materials (PCM) and low-cost pebbles are placed in the middle region, whereas entire tank portion is filled by solid fillers in Single-layered tank system. For a storage tank operating between 563 and 663 K with bed dimensions of 12 and 14.38 m using Solar salt as Heat Transfer Fluid (HTF), it is observed that the duration of discharge for multi-layered tank is 5.32 h whereas it is 4.19 h for single-layered tank with a Reynolds number of 10. The effect of intermediate melting temperature range of PCMs are also analyzed by taking PCMs with sharp as well as intermediate melting ranges. Further, comparison of single and multi-layered systems is carried out by analyzing the temperature profiles and width of both PCM layers. The width of top and bottom PCM layers of tank is varied from 0 to 30% to analyze its effect on the discharging duration. It is observed that multi-layered system provides extra discharge of 1 h with introduction of PCM at top and bottom with a width of 10%. Discharge duration increases with increase in PCM width whereas the percentage increase in duration of discharge with increase in PCM width is comparatively less. It is also seen that PCMs with sharp melting point performs better compared to one having intermediate range of melting temperatures. Multi-layered configuration concept offers best possibilities as integration to CSP plants with desired efficiency.

Solid‐Liquid Adhesion Energies of Composite Propellant Components Determined by Solution Calorimetry

AbstractThe energetic or adhesive interaction between binder matrix and solid fillers as well as plasticizers and fillers is a property determining mechanical properties as strain capacity and stress at maximum or stress at break. To know such interaction energies is therefore of interest. An isoperibolic solution calorimeter is used to measure such interaction energies or heats of immersion of the solid propellant components ammonium perchlorate (AP) and aluminium (AL) with the liquid plasticizers bis‐(2‐ethylhexyl) adipate (DEHA) and azido‐terminated oligomeric glycidylazide (GAP−A). The determined heats indicate wettability and interaction energy in units of energy per surface area of the solid component. For AP, three different grain sizes with mean diameter about 200, 90, 42 μm were used. Results indicate dependence of AP wetting on mean particle diameter: Successful wetting occurs for AP at diameters from above 90 μm. The polar interactions between the ionic AP and GAP−A greatly enhance wetting as compared to DEHA.

Preparation and Structure Study of Water-Blown Polyurethane/RDX Gun Propellant Foams

ABSTRACTWater-blown polyurethane/RDX foamed propellants were prepared using polyols and isocyanate as reactive binder system, hexogen (RDX) as energetic component, triethanolamine (TEA)/Ditin butyl dilaurate (T-12) as composite catalysts, and H2O as blowing agent. The influences of catalyst ratio, blowing agent amount, and solid filler content on the inner porous structure were studied. The results show that the balance of gel rate and cream rate that could be adjusted by catalyst ratio is a major influencing factor on porous structure of foamed propellants. When the ratio of TEA/T-12 was adjusted to 1/0.7, the morphology of the foamed propellant exhibited spherical and closed porous structure. Besides, when the water amount was increased from 0.1% to 0.5%, the pore size increased from 0.43 to 0.64 mm. The contents of RDX particles affected the cell nucleation and thus, the cell geometry. When the blowing agent amount was constant, the increased content of RDX filler led to a decreased pore size. The closed bomb test results showed that foamed propellants burned progressively in an in-depth combustion mode.

Discrete phase method study of ball grid array underfill process using nano-silica filler-reinforced composite-encapsulant with varying filler loadings

Advanced composite-encapsulant with reinforced solid inorganic fillers dispersed in the epoxy resin is regarded as a revolutionary effort in promoting the reliability of electronic device. While various researches have been conducted to study the preparation, chemical and thermomechanical properties of composite-encapsulant using filler-reinforcement, there is however no work found on the visualization aspect of the encapsulant flow progression and filler distribution in the encapsulant. In this paper, the underfilling rheology for encapsulation process of ball grid array (BGA) will be investigated using mono-dispersed nano-silica (SiO2) composite-encapsulant. The filler loadings will be varied in the range of 2–25wt% (weight percent) for optimization purpose. Eventually this work is aimed to provide an in-depth understanding on the impact of the amount of nano-silica fillers being added in the epoxy resin. Finite volume method (FVM) based numerical simulation using discrete phase model (DPM) will be used in this paper. The simulation works reported that the increase in filler loadings of composite-encapsulant effectively lengthen the underfilling process by up to 22% together with a decrease in average encapsulant's pressure. Furthermore, the flow profiles revealed an asymmetry flow front that is prone to form at high filler loadings. This subsequently leads to issues associated to filler's accumulation and swirling. Given these issues, the optimization of filler loadings in composite-encapsulant is of prime importance. Accordingly, this study recommended the usage of 15wt% of nano-silica composite-encapsulant that balances between the relatively lower filling time and with reduced issues relating to filler accumulation and swirling while preserve the improvement in reliability upon the fillers additive. Additionally, the simulation of dispersed particle in continuous fluid phase using DPM had decisively proven its mettle and is hopefully will pioneer a new viable numerical tool in the nano-filler composite polymer study of electronic packaging in near future.

The rheological state of suspensions in varying the surface area of nano-silica particles and molecular weight of the poly(ethylene oxide) matrix

The combined superimposing influences of the surface area of silica nano-particles and molecular weight of polyethylene oxide matrix on the rheological properties of suspensions have been studied. The parameters of both components varied over a wide range: the surface area of silica from 100 to 390 m2/g, molecular weight of poly(ethylene oxide) from 200 to 2 × 105 Da, and concentration of silica from 1 to 13 vol%. In all cases, silica formed aggregates in suspension with apparent diameters of 50 to 230 nm; the higher values were observed for particles with larger surface area. Low-concentration suspensions in an oligomer matrix showed a slight non-Newtonian behavior; the size of silica particles was a determining parameter. Increasing the silica concentration led to dilatancy at high shear stresses. There was a threshold in the concentration dependence of viscosity, beyond which gelation of suspensions occurred. Depending on the silica concentration and molecular weight of the polymeric matrix, the dispersions behaved more like typical colloidal suspensions in a low molecular weight matrix or viscoelastic polymer melts containing an amount of solid filler. An increase in molecular weight of the polymeric matrix resulted in competition between increase in viscosity, appearance of viscoelasticity, and finally the transition from the gel state of a suspension in viscous medium to an elastic fluid.

In situ emulsion cationic polymerization of isoprene onto the surface of graphite oxide sheets

Grafting of polymers onto graphite oxide sheets (GO) has been widely studied in recent years due to the numerous applications of GO-based composites. Herein, polyisoprene (PI) chains were anchored on the surface of GO by in situ cationic polymerization using a “grafting through” approach with allyltrimethoxysilane-modified GO (GO-ATMS). First, the functionalization of GO sheets through the hydrolysis-condensation of allyltrimethoxysilane (ATMS) molecules was qualitatively evidenced by infra-red spectroscopy and X-ray photoelectron spectrometry and a weight content of 4% grafted ATMS was calculated from thermogravimetric analysis. Then, isoprene was in situ polymerized through a one-pot cationic mechanism by using a highly water-dispersible Lewis acid surfactant combined catalyst. For comparison, it was shown that the cationic polymerization of isoprene in presence of un-functionalized GO sheets led to a polyisoprene weight content on the solid filler divided by 3 compared to GO-ATMS. Finally, the compounding of the modified GO/PI composites was performed at a processing temperature of 80°C with 2 phr and 15 phr loadings and it was shown a decrease of the air permeability coefficient of 27% for the vulcanizates with 15 phr loading.

Hollow glass fibers in reinforcing glass ionomer cements

ObjectiveThis study investigated the reinforcing effect of hollow and solid discontinuous glass fiber fillers with two different loading fractions on select mechanical properties of conventional and resin modified glass ionomer cements (GICs). MethodsExperimental fiber reinforced GIC was prepared by adding discontinuous glass fiber (hollow/solid) of 0.5mm in length to the powder of commercial GICs (GC Fuji IX and II LC) with two different weight ratios (5 and 10wt%) using a high speed mixing machine. Fracture toughness, work of fracture, flexural strength, flexural modulus, compressive strength and diametral tensile strength were determined for each experimental and control material. The specimens (n=7) were wet stored (37°C for one day) before testing. Scanning electron microscopy was used to evaluate the microstructure of the experimental fiber reinforced GICs. Fiber length analysis was carried out to investigate the fiber length distribution of experimental GICs. The results were analyzed statistically using ANOVA followed by Tukey's post hoc test. Level of significance was set at 0.05. ResultsAn increase in fracture toughness (280 and 200%) and flexural strength (170 and 140%) of hollow discontinuous glass fiber reinforced (10wt%) conventional and resin modified GICs respectively, were achieved compared to unreinforced materials (p<0.05). Compressive strength did not show any significant differences (p>0.05) between the fiber reinforced and unreinforced GICs. SignificanceThe use of hollow discontinuous glass fiber fillers with conventional and resin modified GIC matrix is a novel reinforcement. It yielded superior toughening and flexural performance compared to the particulate GICs used.

Augmenting the Prejowl: Deciding between Fat, Fillers, and Implants

The prejowl sulcus is a complex anatomic structure that results from several age-related changes in the lower face. These changes include the localized atrophy of a segment of the mandible inferior to the mental foreman, fat atrophy, and dehiscence and laxity of the ligamentous and muscular components of the region. The correction of the prejowl sulcus is rarely accomplished through rhytidectomy alone. Instead, the volume deficit of the sulcus usually requires the replacement of volume. Solid implants, fillers, and fat transfer may be used to improve the contour of the lower face. These can be used in isolation and in conjunction with rhytidectomy. The decision of what method to be used depends on the severity of the deformity, the patient's adjacent anatomy, the patient's wishes, and the skill set of the surgeon.

Tribological studies of epoxy composites with solid and liquid fillers

Epoxy-based composites are promising tribological coatings. The tribological properties of epoxy composites with filler materials such as graphene, graphite, and liquid lubricants (base-oil SN150 and perfluoropolyether) are studied. The composite coatings were applied on cylindrical steel surface and a steel ball was used as the counterface. Tests were conducted at 10N normal load and 0.63m/s linear sliding speed. Among all coatings, epoxy filled with graphene and SN150 lubricant provided the lowest coefficient of friction of 0.09 with wear cycles exceeding 200,000 and specific wear rate of 5.4×10−7mm3/N-m. Speed effects on friction were also evaluated.

Investigation of Soy Protein–based Biostimulant Seed Coating for Broccoli Seedling and Plant Growth Enhancement

This research presents a novel method of using plant-derived protein hydrolysates as seed coating materials. The objective of this study was to develop seed coating formulations using soy flour, a sustainable, inexpensive, and green source, as a biostimulant using broccoli as the model system. A 10% suspension of soy flour was used as the seed treatment binder in all coatings. The solid particulate filler was composed of mixtures of soy flour, cellulose, and diatomaceous earth, together termed as SCD. All SCD components were homogenized in water, then dried and ground to a fine particle size &lt;106 µm. The SCD coatings were applied with rotary pan seed coating equipment at 25% of the seed weight. Increasing the proportion of soy flour increased the seed coating strength and also the time for the coating to disintegrate after soaking in water. As a result, the seed coatings reduced the percentage germination and the germination rate compared with the nontreated control. However, the 10-day-old seedling root and shoot growth showed significant improvement for all SCD coating treatments compared with controls. Plant growth and development was also measured after 30 days in the greenhouse. Fresh weight (FW) and dry weight (DW), leaf area, plant height, leaf development, Soil-Plant Analyses Development (SPAD) index (chlorophyll measurement), and nitrogen (N) per plant were all greater from coatings with 30%, 40%, and 50% soy flour than the noncoated control. Nitrogen, from the soy flour applied in the seed coatings, ranged from 0.024 to 0.073 mg per seed, while the enhanced N per plant ranged from 1.7 to 8.5 mg. The coating treatment with 0.063 mg N per seed resulted in the greatest plant leaf area and highest N content. Nitrogen applied in the seed coating only accounted for 1% to 2% of the enhanced N in the plants, indicating the soy flour acted as a biostimulant rather than a fertilizer.

Improvement of Wear Resistance of UHMWPE by Adding Solid Lubricating Fillers

For estimating effectiveness of adding solid fillers for composites with ultra-high molecular weight polyethylene matrix tribotechnical characteristics of UHMWPE mixture with graphite, molybdenum disulfide and polytetrafluoroethylene were investigated under dry friction, boundary lubrication and abrasion. The optimum filler weight fraction was determined in terms of increasing wear resistance. Permolecular structure and surface topography of wear tracks for UHMWPE composites with different weight fraction of the fillers was studied. The mechanisms of wear of polymeric composites “UHMWPE-graphite”, “UHMWPE-PTFE” and “UHMWPE-MoS2” under dry sliding friction and abrasive wear are discussed.

용접에 의한 Metal 3D Printing의 동향

Metal AM(Additive Manufacturing) has been steadily developed and that is classified into two method. PBF(Powder Bed Fusion) deposited in the bed by the laser or electron beam as a heat source of the powder material and DED(Directed Energy Deposition) deposited by varied heat source of powder and solid filler material. In the developed countries has been applying high productivity process of solid filler metal based DED method to the aerospace and defense sectors. The price of the powder material is quite expensive compared to the solid filler metal. A study on DED method that is based on a solid filler metal is increasing significantly although was low accuracy and degree of freedom.

Sensitivity analysis for thermocline thermal storage tank design

Concentrated solar power coupled with thermal energy storage is a promising approach for providing the world with clean, renewable, sustainable and cost-competitive power on a large scale. Thermocline thermal energy storage has been proposed as an efficient and cost-competitive alternative to the traditional two-tank design. The thermocline thickness is directly linked to the efficiency of the storage tank. Sensitivity analysis is thus applied to a model of the thermocline thickness to identify the parameters that influence it the most. Results indicate that the tank height along with the thermophysical properties of the solid filler material influence the tank efficiency the most, with fluid properties and having a secondary effect.

Compatibility Study Between Synthetic Oil and Vitrified Wastes for Direct Thermal Energy Storage

Compatibility tests were conducted between synthetic oil and potential solid filler materials in a thermocline tank built at the PROMES-CNRS laboratory. These experiments consisted of placing the oil and the solid materials together in small crucibles (2.3 L) and performing compatibility tests at 300 °C and accelerated ageing tests at 330 °C for 500 h. The mutual influence of the oil and the solid materials was assessed through different measurements: X-ray diffraction and scanning electron microscopy. The influence of the solid on the oil was assessed by measuring thermo-physical and chemical properties. While no significant degradation of the oil is measured at 300 °C, at 330 °C, an increase in the oil degradation rate was observed. Its density, thermal conductivity and specific heat did not change, but its viscosity showed a significant increase. However, after accelerated ageing tests at 330 °C, the oil still shows good heat transfer performance. The solid crystalline structure did not change during the test but some of the samples seemed to absorb oil.

Biocomposites based on polylactic acid and olive solid waste fillers: Effect of two compatibilization approaches on the physicochemical, rheological, and mechanical properties

A new valorization strategy for Olive Solid Waste (OSW) has been carried out consisting in incorporating this biomass as filler in a biopolymer matrix. In this study, biocomposites based on poly(d,l‐lactide) (PLA) and OSW fillers were prepared with various filler contents. It was highlighted that the inclusion of OSW under high temperatures resulted in the degradation of the matrix leading to a reduction of the viscoelastic properties and molar masses. Nevertheless, it was shown that this degradation of PLA matrix could be attenuated through two approaches. The first was chemical and consisted in using a chain extender agent named Joncryl, containing glycidyl methacrylate (GMA) functions. The second route was physical and involved coating the OSW with the hydrophobic biopolymer poly(ε‐caprolactone) followed by mixing with PLA. Meanwhile, the effect of the OSW with and without Joncryl on the thermal stability, the melt and crystallization properties was assessed. Furthermore, the rheological properties of the controlled systems PLA/OSW/Joncryl and/or PLA/(OSW) coated with PCL were investigated in the molten state. The improvement of the shear viscoelastic properties corroborated the measured molar masses. The physicochemical matrix/filler interactions had to be taken into account to explain the improved rheological, morphological and tensile mechanical properties. POLYM. COMPOS., 39:E152–E163, 2018. © 2016 Society of Plastics Engineers

A study of the influence of the microstructure of one type of bitumen grade on the performance as a binder

Six different bitumina of comparable PEN grade were investigated to gain a relation between the composition and the development of microstructures and their performance as binder material e.g. for road constructions. It was shown, that especially bitumina with explicit microstructures show an intense interaction between the asphaltene nucleated crystals (peri/catana phase) and solid (aggregate and/or filler) surfaces. Consequently, the developed adhesive/cohesive interaction is also stronger in case of such bitumina than in case of bitumina with extended continuous liquid phases (perpetua phase) and such bitumina seem to be well suited for an application as binder material. This was possible by employing a new designed micro-direct tensile test for quantitative determination of adhesive forces including the possibility to study the nature of the failure upon testing.The obtained data were correlated with AFM data from surface structure analysis and verified by other data from literature and other experiments regarding the adhesive interaction of parts of the bitumen with solid surfaces.

The effect of the physical boundary conditions on the thermal performance of molten salt thermocline tank

Methods of solving some of the critical design consideration associated with the thermocline storage system with unusual physical boundary conditions bring new problems: the effect of insert liner should not be ignored with small solid filler size, and it is hard to take advantage of truncated cone shaped tank for decreasing the potential of thermal ratcheting and increasing the maximum height of the tank, both while maintaining a good efficiency.In this study, a transient two-dimensional and two-temperature model is developed to investigate the heat transfer and fluid dynamics in a molten salt thermocline thermal storage system. After model validation, the effects of physical boundary conditions including insert liner and sloped wall on the thermal performance of thermocline storage system is investigated through the entropy generation analysis.The results show that both of the axial and radial convex size of the liner should be as small as possible, resulting in smaller average velocity and less disturbance in the flow. The truncated cone shaped tank has an advantage in the charging process with low entropy generation in molten salt and solid material, while it goes against the discharging process. It is found that larger inclined angle of the sloped wall causes smaller thermocline thickness and entropy generation with the same tank height and tank volume for truncated cone shaped tanks. Besides, larger tank height is better for the truncated cone shaped tanks with the same tank volume.

GAP/CL-20-Based Compound Explosive: A New Booster Formulation Used in a Small-Sized Initiation Network

ABSTRACTWith ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and glycidyl azide polymer (GAP) as the solid filler and binder, respectively, GAP/CL-20-based compound explosives were designed and prepared. Using micro injection charge technology, the compound explosives were packed into small grooves to explore their application in a small-sized initiation network. The detonation reliability, detonation velocity, mechanical sensitivity, shock sensitivity, and brisance of the explosive were measured and analyzed. The results show that when the solid content of CL-20 is 82 wt%, the explosive charged in the groove has a smooth surface from a macroscopic view. From a microscopic view, a coarse surface is bonded with many CL-20 particles by GAP binder. The GAP/CL-20-based explosive charge successfully generates detonation waves in a groove larger than 0.6 mm × 0.6 mm. When the charge density in the groove is 1.68 g·cm−3 (90% theoretical maximum density), the detonation velocity reaches 7,290 m·s−1. Moreover, this kind of explosive is characterized by low impact and shock sensitivity.