A review of heat treatment on polyacrylonitrile fiber

The aim of this review article on recent developments of mechanochemistry (nowadays established as a part of chemistry) is to provide a comprehensive overview of advances achieved in the field of atomistic processes, phase transformations, simple and multicomponent nanosystems and peculiarities of mechanochemical reactions. Industrial aspects with successful penetration into fields like materials engineering, heterogeneous catalysis and extractive metallurgy are also reviewed. The hallmarks of mechanochemistry include influencing reactivity of solids by the presence of solid-state defects, interphases and relaxation phenomena, enabling processes to take place under non-equilibrium conditions, creating a well-crystallized core of nanoparticles with disordered near-surface shell regions and performing simple dry time-convenient one-step syntheses. Underlying these hallmarks are technological consequences like preparing new nanomaterials with the desired properties or producing these materials in a reproducible way with high yield and under simple and easy operating conditions. The last but not least hallmark is enabling work under environmentally friendly and essentially waste-free conditions (822 references).

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Hallmarks of mechanochemistry: From nanoparticles to technology

https://hal.archives-ouvertes.fr/hal-00922073/document

Investigation of the carbonation mechanism of \{CH\} and C-S-H in terms of kinetics, microstructure changes and moisture properties

Cemented carbides cover a wide range of applications in many relevant industries, i.e. as cutting tools (turning, milling, drilling) for machining of metal components in the automotive and/or aerospace industry, as components of drill bits or road headers in the rock tools and mining area or as wear parts in wire drawing dies or punch tools. In this review selected cemented carbide and cermet microstructures are presented. The focus is on microstructures, both those that are already established in the cemented carbide industry and those which have drawn scientific attention due to new potential applications. Cemented carbides are here divided in four groups based on microstructure and chemistry: WC morphology and chemistry, cubic carbide containing cemented carbide and cermets, functionally graded cemented carbides, and binder design of cemented carbides. Furthermore, this review covers some historical background that motivated the microstructure design as well as the status of each class of materials nowadays. The paper aims at categorising cemented carbides in a structured way and to serve as an introduction to cemented carbide microstructures for engineers, researchers and scientists.

Cemented carbide microstructures: a review

Book Review: 1992. Life in Amber

Talc from Puebla de Lillo, Spain. II. Effect of dry grinding on particle size and shape

https://digital.csic.es/bitstream/10261/39867/3/Thermal%20study.pdf

Thermal study of the effect of several solvents on polymerization of acrylonitrile and their subsequent pyrolysis

The effects of ultrasound treatment on the mean particle size, crystal structure, crystallite dimensions and specific surface area of natural muscovite and biotite samples have been investigated. Sonication of macroscopic flakes of muscovite and biotite produced a drastic particle-size reduction. The conditions for the preparation of micron and submicron-sized muscovite and biotite particles of narrow particle-size distribution by sonochemistry are described. The effect of sonication on particle-size reduction is more significant for muscovite than for biotite. Thus, for long sonication times (100 h), submicron and micron particles are predominant in muscovite and biotite, respectively. The resulting materials are crystalline, as assayed by X-ray diffraction, only broadening of the diffraction lines due to size-reduction was observed. Nuclear magnetic resonance studies revealed that the coordination of Al and Si was not modified by the treatment. Chemical analysis showed that the composition of the sample was not affected by the sonication except for a small contamination by Ti from the tip cup of the sonication instrument.

Effect of sonication on particle-size distribution in natural muscovite and biotite

The low temperature of decomposition of some calcium carbonates and the bending of the TG curves of hydrated cement between 500 and 800°C suggested the presence of some complex compound(s), which needed complementary investigation (XRD, TG). Stepwise transformation of portlandite (and/or lime) into calcium carbonate, with intermediate steps of calcium carbonate hydroxide hydrates (CCH-1 to CCH-5), was indicated by the previous study of two OPC.

Gradual transformation of Ca(OH)2 into CaCO3 on cement hydration

Cermets based on Ti(C,N) have interesting properties, such as high wear resistance, high chemical stability and good mechanical strength at high temperature, but to become a viable alternative to cemented carbides, the fracture toughness and damage tolerance must be significantly improved. Complete solid-solution cermets (CSCs) have been proposed to further improve the mechanical properties of these materials. However, to develop this family of cermets with a high level of quality and reliability, using pre-fabricated complex carbonitrides is necessary instead of unalloyed mixtures as the raw ceramic material. A mechanochemical process called mechanically induced self-sustaining reaction (MSR) is suitable to obtain these complex carbonitrides with high stoichiometric control. On the other hand, high entropy alloys (HEAs), which can also be obtained by mechanochemical processes, are a good candidate to replace the current binder phase in cermets because they exhibit high strength and ductility at high temperature and good resistance to both wear and corrosion. In this work, a new family of CSCs based on (Ti,Ta,Nb)CxN1 − x with HEAs belonging to the Fe-Co-Ni-Cr-Mn-V system as the binder phase is developed by mechanochemical processes. With only two constituent phases, these cermets have a simple microstructure but a high compositional complexity because both the ceramic and binder phases are complex solid solutions with at least five components.

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M.A. Avilés

Papers

Talc from Puebla de Lillo, Spain. II. Effect of dry grinding on particle size and shape

Thermal study of the effect of several solvents on polymerization of acrylonitrile and their subsequent pyrolysis

Effect of sonication on particle-size distribution in natural muscovite and biotite

Gradual transformation of Ca(OH)2 into CaCO3 on cement hydration

A new family of cermets: Chemically complex but microstructurally simple