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[en] Highlights: ► The proper filler metal has been developed, especially for contents of Mg and Si. ► The pressure device has been designed for specimen in vacuum brazing process. ► The accurate measurement method for shear strength of lap joint has been found. ► The brazing temperature of 560 °C has been optimised. ► The micro-mechanism has been discussed for SiCp/Al composites’ brazing joint. - Abstract: Aluminium matrix composites with high volume fractions of SiC particles, as the reinforcements, are potentially suitable materials for electronic packaging. These composites, due to their poor weldability, however, have very limited applications. The microstructure and shear strengths of the bonds made in 55 vol.% SiCp/A356 composite, using an aluminium based filler alloy containing Cu, Si, Mg and Ni, were investigated in this paper. The brazing temperature had a clear effect on the bond integrity, and the samples brazed at 560 °C demonstrated good bonding between the filler alloy and the SiC particles. The maximum shear strength achieved in this work was 102 MPa.
[en] We studied the characteristics of 316LN welded joints produced by different welding fillers through temperature and field dependent magnetization measurements. The magnetic permeability of welded joints showed significant variations depending on the used welding fillers. Qualitative changes from 316LN base material were observed in the field dependent magnetization of welded specimens. While the self-welded and low-Mn content filler-welded samples showed signs of secondary phase formation, considerable suppression of the secondary phase formation was observed in high-Mn content filler-welded samples. The austenitic-structure-retaining property was also observed in the FE-SEM microstructure.
[en] The inner demagnetization factor Ni of polymer-bonded soft magnetic composites (PBSMC) varying in filler material and filler content C was measured, using a computer-controlled measurement system. For all materials the results show a decrease from an inner demagnetization factor close to the demagnetization factor of a single particle to Ni∼0 on increasing the magnetic content C. Measurement data of a selected material were compared with a model derived from an effective medium theory using the composite's effective susceptibility and show superb accordance
[en] Research project, carbon blacks were produced by furnace (S324) and channel(K354) methods were added to elastomer mixture and vulcanization process carried out with gamma rays and physical chemical properties are learned. Two types of fillers with different amounts were included to composite material which formed by based on butadiene nitrile rubber nano zinc oxide particles and disulphurchloridebenzyl used as crosslinking agent. The obtained mixture was vulcanized by 250 kGr gamma rays. It is shown that, strength, hardness and the stiffness of vulcanized materials are causes to change the physical-mechanical properties. Moreover, impact of the amount and type of filler. According to the influence of the elastomer mixed with fillers improves the yield amount of carbon-rubber gels (CRG)
[en] Highlights: • Investigated keff of PBT composites contain spherical and platelet-shaped hBN. • PMC filled with spherical hBN of relatively small size possessed the highest keff. • Hybrid hBN fillers showed synergistic effect on PMC's keff. • Platelet-shaped hBN of significant size difference exhibited most increase in keff.
[en] Full text: The influence of preliminary gammaradiation on charge state of thin finedispersed polymer composites based on polystyrene (PS) and piezoceramics of PZT with particle size of 1 mkm is investigated. PZT particles were separated in the polymer solvent by the sedimation method and then were introduced into polymer matrix.RTL,TSD,IR researches of these composites were conducted.It is established by SEM and AFM investigations, that at certain concentrations of fillers (Φ=20%) in polymer composite the clusters predominate and this leads to irregularity of surface structure.At Φ=10% the phusical structure of polymer composite mainly noncluster and more perfect.Investigation of RTL properties of these composites irradiated by different doses of γ radiation showed, that in non-cluster system (Φ=10%) at dose of D=30 kGy the amplitude of RTL peaks more wide, amplitude is relatively less and second peaks are observed.This was explained by us with features of interphase structure.It is assumed by us,that at monodispersity of filler the physical structure around introduced particle is identical, that is the phusical structure of traps is the same.It may be result of this factor,that monodispersity of filler leads to identical taking place of crystallization process of polymer on surface of introduced particles.Because of distribution of particles of same sizes without forming of clusters, the same area around particle will formed crystallized polymer chains of same kinetics units.
[en] Full text: The electric properties of the films of PP and compositions on their vase are investigated. As the filler are used the piezoceramics of PCR-3M and PCR-7. The obtained experimantal results is analyzed considering the composition of polymer-segnetoelectric as the manylayer dielectric consisting of a polymer, active piezophase (ceramic) and transition layer. It is found, that at the optimal polarization temperature on the dependence of piezoelectric phase, the maximal charging of composite electret takes place at the 5% vol. for romboedric and 10% vol. for tetragonal structure. It is established that at the same conductivity of polymer phase and piezoelectric particle is obtained the optimal charging regime of electret. It is suggested, the mechanism of formation of stable electret effect in the system of polymer-segnetopiezoelectric at thermopolarization
[en] A new model is proposed to predict the thermal conductivities of laminated composites, where the Eshelby method modified with Mori-Tanaka's mean field approach is employed to consider the interaction effect. Based on the equivalency of composites with penny-shaped fillers and composites with layers of components, each lamina is considered as a penny-shaped filler and its thermal conductivities are computed by modified Eshelby method. The laminated composites are then simulated as the matrix and penny-shaped fillers of different thermal conductivities. By comparing the results of the laminated composites predicted by the present model and conventional approach combined with the potential theory and electrical analogy, the applicability of the present model to predict the thermal conductivities of the laminated composites is validated
[en] Complete text of publication follows. In this paper the influence of halloysite structure on the properties of melt-prepared polymer nanocomposites have been studied. Intercalation of halloysite (HLS) carried out in solution as well as by dry mechanochemical method has been investigated by vibrational spectroscopic techniques. Except of currently used modifiers (alkylamines, silanes), an intensive study of organo-clay nanocomplexes (with potassium-acetate, urea, formamide and acetamide) has been investigated and new structural models (as well as reaction pathways) were proposed. It was found that modification of halloysite by alkylamines as well as silanes did not lead to intercalated structure of halloysite. Mechanochemical treatment with urea, however, resulted in an intensive intercalation of halloysite. Surface activation of the mineral has been achieved by the thermal treatment of the complex. The impact of the intercalated structure of halloysite was confirmed by improving mechanical properties, as well as by reduction of flammability of PP/halloysite nanocomposites. The investigation of the structure of polymer nanocomposites based on intercalated halloysite confirmed considerable reduction of particle size and high degree of filler exfoliation. The achieved results confirmed that there is a potential for future utilisation of natural halloysites for production of exfoliated polymer nanocomposites with outstanding end use properties.