Purpose: Purpose of this paper is the applying of new technology in injection moulding technique and investigation of reinforcement of PC as dispersed phase inside PP matrix (Table 1). Second aim of work is enrichment of those composites by nanoclay and analyzing mechanical behaviour of nanocomposites. Design/methodology/approach: According to design of experiments (DOE) specimens were injection moulded in the shape of rectangular bars. Additionally advanced technology of melt manipulation inside mold cavity after injection was used. To achieve this purpose Ferromatik Milacron injection moulding machine, equipped with externally controlled mold was used. Findings: Addition of nanoclay clearly presents highly reinforced system, especially for neat matrix. Evenly dispersed PC particles within PP majority show reinforcement as well. Inducement of shear rate in injection moulding radically improved absorption of energy in nanocomposite. Research limitations/implications: Different variation of material composition, such combination with other polymers and use of different reinforcements (flexible or either rigid) is required to be checked in the further work. Practical implications: Reinforcement obtained thanks to dispersed phase and nanofillers creates composites with improved mechanical properties. Originality/value: Morphology development reflects on mechanical behaviour. Its manipulation may affect and improve mechanical properties. Use of advanced technologies opens wide range of possibilities in processing of polymer based systems. At present there is limited number of research of processing-structure-properties relationships of polymer-polymer composites and nanocomposites.

Silicon nitride ceramics - review of structure, processing and properties

The sintering behavior of olivine and olivine-basalt aggregates has been examined at temperatures near 1,300° C. Experimental factors contributing to rapid sintering kinetics and high-density, fine-grained specimens include: (i) the uniform dispersion of basalt throughout the specimen, (ii) a very fine, uniform particle size for the olivine powder, (iii) oxygen fugacities near the high PO2 end of the olivine stability field, and (iv) rapid heating to the sintering temperature. Olivine-basalt specimens prepared from olivine particles coated with a synthetic basalt achieve chemical and microstructural equilibrium more rapidly, as well as produce higher density and finer grain-sized aggregates, than do specimens prepared by mechanical mixing of olivine and natural basalt powders. The grain boundary mobility for olivine, measured for olivine-basalt aggregates which have undergone secondary recrystallization, is on the order of 2×10−15 (m/s)/(N/m2) in the temperature range 1,300–1,400° C. Solution-precipitation (pressure-solution) processes make an important contribution to the development of the microstructure in olivine-basalt aggregates.

Sintering of olivine and olivine-basalt aggregates

Cemented carbides based on tungsten carbide and cobalt arecommonly produced by a powder metallurgy route including liquidphase sintering. The pressed compact densifies to almost halfits volume duri ...

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Cemented Carbide Sintering : Constitutive Relations and Microstructural Evolution

The Voskhod podiform chromitite is one of more than 30 chromitite deposits that collectively form the Main Ore Field (MOF) within the Kempirsai Massif, in Kazakhstan. The MOF is the largest podiform chromitite ore-field in the world. The Voskhod deposit, encased in a serpentinised dunite halo, is situated within harzburgite units that comprise the mantle sequence of the Kempirsai ophiolite. This study arose from a unique opportunity to work on drill core samples through an un-mined podiform chromite deposit and investigate its internal structure, composition and genesis.
The 18Mt ore-body has a strike of 600 m, is 170 m to 360 m wide and has an average thickness of 39 m. It has an immediate dunite halo between 1 m and 5 m thick. The ore body is made up of multiple stacked chromitite layers. Mineralised layers are separated by barren dunite or by weakly disseminated dunite lenses ranging from 5 – 45 m) units of massive chromite (>80% chromite), with progression towards the south west disseminated chromite (10 – 40% chromite) becomes increasingly abundant. Drill core logging and cross-section profiling of the internal structure of the ore body has identified an intricately connected network of what appear to be chromite-filled channel-ways.
Outside of the halo the host rocks are inter-layered harzburgite and dunite. Accessory chromite in harzburgite has an average Cr# of 0.31 compared to Cr# 0.49 in the dunite. The harzburgites are depleted, having formed from intermediate degrees of partial melting (~15 – 18 %) of a fertile mantle source at a mid-ocean ridge (MOR) setting. The dunite units have transitional geochemical fingerprints that imply they formed from the interaction of MOR mantle harzburgite with both mid ocean ridge baslt-melt and an arc derived-melt. They are not the products of extremely high degrees of partial melting.
The encasing dunite halo is extensively serpentinised (>80%). Chromite is only present as an accessory phase having an average Cr# of 0.62. The dunite has a geochemical signature indicating that it formed by reaction between residual harzburgite and a boninite melt in supra-subduction zone (SSZ) tectonic setting.
A variety of geochemical fingerprints have been identified; residual MOR harzburgite, reacted-MOR dunite, reacted-SSZ dunite and harzburgite, indicating that the mantle section has had a
ii
polygenetic tectonic evolution, recording both ocean basin opening (MOR setting) and closing (SSZ setting) events.
Trace element and REE whole rock geochemistry of the chromitites and associated host rocks provide evidence of depletion and a later-stage LREE-enrichment event. LREE-enrichment is most intense within and immediately adjacent to the chromitite.
Chromites from the ore zone are at the Cr-rich extreme for podiform chromites (Cr# ave. 0.80-0.85) and are TiO2 poor (ave. 0.16 wt%), similar to chromite in boninite worldwide and nearby. Al/Ti ratios have been used to calculate the composition of the parent melts from which the Voskhod podiform chromitite crystallised: compositions that are synonymous with a boninite melt composition.
Chemical variation in chromite is systematic and on a much smaller scale than was anticipated. Even variations in a single thin section provide key evidence for different magmatic processes. An apparent melt-rock reaction in harzburgite has been examined in freeze-frame.
The chromite chemistry has been investigated at 50 cm, 1 cm and 1 mm scales. Compositional differences were identified on the basis of MgO% and FeO(t)% compositions. Diagrams FeO-Fe2O3 and Cr# - Mg# were used to demonstrate the variations and identify relationships. Broad cryptic layering on a 50 cm scale has been found as well as fine-cryptic layering on a 1 – 8 cm scale. The variations are interpreted to reflect differences in the mineral phases crystallised from the melt; periods when on chromite only crystallised are distinguished from periods when both chromite with olivine crystallised. It seems likely that the deposit is made up of thousands of episodes of chromite accumulation that formed in an intermittently replenished open-system.
It also seems likely that the conduit was never a single melt-filled cavity; instead melt flow was focused through the mantle over an extended period. The conduit appears to be comprised of multiple branches, as chromite (± olivine) crystallised from the melt the channel-way became blocked and the melt was forced to deviate and make a new pathway through the mantle. As time elapsed the process resulted in the formation of stacked chromitite lenses, creating an orebody that has an internal arrangement of chromitite and dunite unites which resemble a stacked braided 'delta'.

Podiform chromite at Voskhod, Kazakhstan

The process of the liquid-phase sintering is quantitatively considered from the viewpoint of the thermodynamic approach in application to isothermal conditions. The model is based on the assumption that a metastable liquid phase is formed near the contact of two particles. The most probable way of the sintering process is defined by variation of configuration of the system consisting of two partially molten particles and minimization of the free energy of the system. As a result of calculations based on the model, the following are obtained: i) step-by-step configurations of partially molten particles during the process of sintering, and ii) the intensity of the solid-liquid transition as a function of the sizes of the particles and their temperature.

M. Humenik

Papers

Sintering in the presence of a liquid phase.