Papers by Keyword: Dispersion Methods

Abstract: The article describes the influence of chrysotile nanofibers dispersion introduction on the properties of the cement matrix. Comparison of the dispersion level of suspensions obtained using cavitation and ultrasonic processing methods is presented. The positive effect of chrysotile fibers application on the strength characteristics of the material has been confirmed. A 34% increase in the compressive strength of the samples was achieved on the 7th day of hardening, while on the 28th day it increased by 36% and with the steam treatment - by 38% compared to the reference sample. Laser particle size analysis confirmed the predominance of the nanosized component of chrysotile fibers in the suspension, which affected the structuring of the cement matrix. The results of the differential thermography, IR spectrometry, X-ray microanalysis and scanning electron microscopy of the samples are also presented. The analysis methods confirmed that introduction of chrysotile nanofibers suspension into the composition of a cement binder makes it possible to significantly vary the structure and morphology of new formations in fine-grained concrete. It also changes the quantitative and qualitative phase composition of the material with the formation of calcium silicate hydrates of lower basicity, leading to an increase in the strength of cement concrete.

Abstract: The metal and nano-ceramic nanocomposite coatings were prepared on gray cast iron surface by electrodepositon. The nickel and cobalt were used as metal matrix of coating, and the nano-Al2O3 was chosen as second-phase particulates, which had good chemical stability, high microhardness and good wear resistance. The morphology of composite coatings was flatter and microstructure was denser than pure nickel and cobalt coatings. The composite coatings were fabricated by different dispersion methods such as high speed mechanical stir, ultrasonic vibration and ultrasonic vibration together with mechanical stir. The result indicated the nano-Al2O3/Ni+Co composite coating with fine and compact microstructure are obtained compared with pure Ni-Co coating. The nanoparticles were dispersion evenly when dispersion style was ultrasonic vibration together with mechanical stir according to composite coatings SEM images of different dispersion style. The concentration of nanoparticulates reached a maximum value when the dispersion style was ultrasonic vibration together with mechanical stir, at the same time the mechanical property such as microhardness reached a maximum value also. The reason was that nano-Al2O3 caused dispersive strengthening and grain refining.