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Positron-positronium annihilation spectrum were analyzed using four-component fitting procedures. It is shown that this technique can be used to investigation of nanopores transformation in humidity-sensitive MgO- Al2O3 ceramics as porosimetry method. It is established that the third component of lifetime spectra gives information about ortho-positronium decaying in nanopores with water and fourth...
The sol-gel method was used to prepare the high purity lead zirconate titanate Pb(Zr,Ti)O3 (PZT) piezoelectric ceramic powders. To determine the optimum fabrication process, the influence of calcined conditions and sintering conditions on the characteristics of PZT bulk was studied. After calcined at 900°C for 4hr, and then sintered at 1100°C for 2hr, the density of the bulk ceramics nearly equal...
Influence of the non-cavitational powerful ultrasonic action (PUA) on the particle size distribution and lattice parameters of crystallites of zirconia and alumina dry nanopowders have been studied. The ultrasonic treatment occurred into the acoustic waveguide having a cavity, filled by dry nanostructured powder (NP). The PUA of different power was used to various dry NP: ZrO2-8%Y2O3 (TZ-8Y, TOSOH);...
The object of this study is to investigate the sintering processes of sewage sludge ceramic pellets (SSCP) as filter media. The effects of adding coal fly ash and farmland clay were tested, and the feasibility of using SSCPs in a biological aerated filter (BAF) was determined by comparing their performance with that of commercial ceramic pellets (CCP). Unlike the procedure to make lightweight sewage...
The initial motivation for this work was to accomplish an easy way to manufacture different geometries of ultrasonic transducers and arrays using a PZT powder, combined with a standard process to have repetitive series of them. The piezoelectric thick film was obtained using a PZT paste and applying it by screen printing on an alumina substrate. Then, the film was drying and sintered with a temperature-time...
Recently, LTCC (low-temperature co-fired ceramic) technology has increasingly found applications beyond pure electronics, in fields such as microfluidics, sensors and actuators, due to the ease of shaping the tapes in the green (unfired) state. Accurate control of hollow structures such as channels, membranes, cavities and gaps below cantilevers has remained difficult, however, although carbon-based...
In this work, a two-dimensional numerical model for the convective drying process of ceramic shell layers was developed. The governing system of fully coupled non-linear partial differential equations describing the process was derived from a mechanistic approach along with the implementation of continuum model. The most extensive formulation of the material used in many hygrothermal and soil transport...
Recent antenna designs have a complex 3D distribution of different materials that must form a cohesive, and often highly asymmetric entity. The distinct materials in such designs have special dielectric and magnetic properties, and often low electromagnetic losses. This implies that the materials of choice are mainly oxides that are made by ceramic routes for practical reasons. Ceramic routes start...
Summary form only given. During the last decades microwave technology gathered growing industrial interest for thermal processing of various kinds of materials. Many industrial processes using microwave technology, such as for example food processing, drying, rubber vulcanization or polymer curing, were already successfully realized by use of microwave technology. Here the benefit of microwave volumetric...
It is shown, that directional freeze-drying is capable of forming dense and porous ceramic structures in one processing step. This promising technique makes for high porosities (up to 90%), the development of aligned pores and graded porosity while sintering shrinkage is reduced. Research on yttrium stabilized zirconia (YSZ) and subsequently fine copper particle systems, indicates that this method...
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