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The preparation process and the properties of Al2O3-W nanocomposites obtained by gelcasting are reported. The novelty of the synthesis path is the formation of nano-tungsten particles in an in situ reduction of water-soluble precursor during pressureless sintering. The use of water-soluble salt as a tungsten precursor ensured highly homogenous distribution of reinforcing particles and good adhesion between ceramic and metal phases. The maximum content of tungsten in the composites was approximately 0.5 wt%. The size of the reinforcing particles was less than 100 nm. Presence of metallic tungsten and tungsten carbide (W2C) in the composites lead to the improvement of mechanical parameters: an increase of hardness by about 10 % and of fracture toughness by about 20 %, compared to the reference sample of pure aluminum oxide.

0.83 Pb(Zr1/2Ti1/2)O3-0.11Pb(Zn1/3Nb2/3)O3-0.06Pb(Ni1/3Nb2/3)O3 (PZNNT) samples with plate-like PbTiO3 (PT) template were prepared using tape casting technology. The microstructure evolution and reaction mechanism between the matrix and PT template was investigated systematically. The quench heat treatment experiment was designed and the microstructure was evaluated. The results showed that the plate-like PT template has relatively low thermal stability which would decompose to form Pb-rich liquid phase and Ti-rich region at the sintering temperature of 900 °C–1050 °C. Plate-like PT template reacted with the PZNNT matrix materials during the sintering process, which did not contribute to the grain growth orientation for PZNNT matrix. Finally, the mechanism of grain growth for the PZNNT ceramics with plate-like PT template is clarified. This work demonstrated that the thermal stability of plate-like template is one of the key factors for fabricating textured piezoelectric ceramics.

In this work, the preparation of foam-gelcasting was simplified with a copolymer of isobutylene and maleic anhydride (Isobam), avoiding the traditional gelling system including many additives such as monomer, cross-linking agent, initiator and catalyst. Highly porous yttria-stabilized zirconia (YSZ) ceramics with 76.2–84.9% porosity were prepared via foam-gelcasting method using YSZ powder as the raw material, Isobam as the dispersant and gelling agent, triethanolamine lauryl sulfate as the foaming agent and sodium carboxymethyl cellulose as the foam stabilizing agent. The effects of solid loading, the content of foaming agent as well as sintering temperature were investigated. With the increase in solid loading of slurries, lower porosity was obtained, and the compressive strength and thermal conductivity showed a tendency of increase. Porous YSZ ceramics with compressive strength of 0.69–3.66 MPa showed low thermal conductivity in the range of 0.137–0.254 W/(m·K) at room temperature. The as-prepared sample showed good thermal insulating performance at high temperature. The km in GM model was during 0.4–0.7, which indicated the pore structure containing the internal and external porosities. This work provides a facile method for the fabrication of porous YSZ ceramics which can be potentially applied as thermal insulation materials at high temperature.

Herein, we present manifold possibilities of using saccharides and their derivatives in colloidal processing of ceramics. Sugar-based compounds are attractive alternatives for commonly used organic additives, because they are renewable materials, are non-toxic to human skin, and have a positive influence on the rheological behavior and stability of ceramic suspensions which is reflected in the properties of green and sintered bodies. The examined substances include sugar acids (galacturonic and lactobionic acid) as highly effective deflocculants for nanopowders; acryloyl derivatives of monosaccharides and sugar alcohols as organic monomers in gelcasting; polysaccharides as binders; and l-ascorbic acid as an activator of radical polymerization in gelcasting. The multifunctionality of the selected compounds as well as their thermal decomposition during sintering of ceramics is discussed. The study also reviews the related literature focusing on sugar-based compounds in ceramic processing.

A sample of 0.83Pb(Zr0.5Ti0.5)O3-0.11Pb(Zn1/3Nb2/3)O3-0.06Pb(Ni1/3Nb2/3)O3 (PZNNT) to which MnO2 was added, with a high mechanical quality factor (Qm) and a good transduction coefficient (d33×g33), were systematically investigated. Based on the SEM analysis there existed two kinds of “secondary phases”, Rich Ti and Rich Zn phases, which arose due to the B-site substation of PZNNT-based ceramics by manganese ions. One phase was due to the Mn3+ replacing the Ti4+ to create oxygen vacancies and induce the hardening effect. Another phase was due to the Mn2+ replacing the Zn-site to stabilize the perovskite phase. When the addition of MnO2 reached the solubility limit of 1.5 mol% in the PZNNT-based ceramics, the sample showed optimal electrical properties (Qm=357, d33×g33=9859 × 10−15 m2/N, kp=0.56), which suggested its potential application for piezoelectric energy harvesting in larger field excitation environments.

Transparent KSr2Nb5O15 (KSN) lead-free ferroelectric ceramics have been synthesized via modified pressureless sintering method. A significant photochromic effect was observed for the transparent KSN ceramics prepared without rare-earth dopant modification. The piezoelectric properties depend on the grain orientations were investigated. The optical transmittance of the KSN ceramics is greater than 40% in the wavelength range of 530–800 nm. After NUV irradiation, the absorbance was enhanced by more than 40% in a broad visible range (more than 79%). The absorbance returned to the initial value after a thermal bleaching process. The results of the cycling tests and response experiments showed the stability and saturation of the photochromic effect. In addition, the possible photochromic mechanism of the KSN ceramics is discussed and the photochromic centers are identified. This transparent KSN ceramics exhibits an obvious photochromic effect and is a potential candidate materials for optical data storage and information recording applications.

This work focuses on shear thickening fluids (STFs) as ceramic–polymer composites with outstanding protective properties. The investigation aims to determine the influence of raw material parameters on the functional properties of STFs. The following analyses were used to characterize both the raw materials and the STFs: scanning electron microscopy, dynamic light scattering, matrix-assisted laser desorption/ionization time-of-flight, chemical sorption analysis, rheological analysis, and kinetic energy dissipation tests. It was confirmed that the morphology of the solid particles plays a key role in designing the rheological and protective properties of STFs. In the case of irregular silica, shear thickening properties can be obtained from a solid content of 12.5 vol.%. For spherical silica, the limit for achieving shear thickening behavior is 40 vol.%. The viscosity curve analysis allowed for the introduction of a new parameter defining the functional properties of STFs: the technological critical shear rate. The ability of STFs to dissipate kinetic energy was determined using a unique device that allows pure fluids to be tested without prior encapsulation. Because of this, it was possible to observe even slight differences in the protective properties between different STFs, which has not been possible so far. During tests with an energy of 50 J, the dissipation factor was over 96%.

The paper presents research on ferroelectric ceramic-polymer composites based on barium-strontium titanate and water-thinnable polymeric dispersions, obtained by using tape casting method. Barium strontium titanate with the assumed stoichiometry Ba0,65Sr0,35TiO3 was synthesized by the high temperature solid-state reaction. Water-thinnable polymeric dispersions were synthesized from butyl acrylate, styrene and tert-butyl acrylate containing different amounts of individual monomers. Then, the ceramic-polymer composites were obtained by tape casting. The influence of the chemical structure of synthesized binders on the rheological properties of the slurries and on physicochemical and electrical properties (characterized by using Broadband Dielectric Spectroscopy, BDS) of ceramic-polymer composites were investigated.

Novel plate-like B-site complex Bi4(ZrxTi1-x)3O12 microcrystals consisted with both (Bi2O2)2+ layer and Zr4+substituted [Bi2Ti3O10]2- blocks have been synthesized through molten salt method. With the increase of Zr4+ content, the lattice constant of Bi4(ZrxTi1-x)3O12 increases. From the Raman analysis, the bending vibration was mainly influenced by the Zr4+ content, while both of bending and stretching vibration was influenced at relative high calcination temperature. The reaction conversion process was mainly controlled by the solution-precipitation mechanism and TiO2 provided the basis crystal nucleation in NaCl-KCl molten salt, where the reactant ionic can precipitation, epitaxial growth and finally generated the final bismuth layer-structure products. Finally, fine crystallinity and orientation of plate-like Zr substituted Bi4(Zr0.1Ti0.9)3O12 microcrystals with high aspect ratio can be successful fabricated at 900 °C, which paved a way to design and fabricate the novel plate-like B-site complex perovskite compounds in the future.

Dielectric tunable composites are of importance to fabricate flexible electronic devices. However, the achievement of the desirable tunability is limited by the defects between polymer matrix and inorganic fillers, which results in high dielectric loss and low electric breakdown strength. In this contribution of Ba0.6Sr0.4TiO3/((acrylonitrile-butadiene-styrene)-(poly(vinylidene fluoride)) (BST/ABS-PVDF) composites, such limitation was overcome via surface-modifying fillers and a design of binary polymer matrix of ABS-PVDF. The ratio of ABS-PVDF matrix was initially optimized concerning microstructure and dielectric performances. The dielectric constant (from 13 to 27 at 1 kHz) and tunability (1.3 to 3.8% at 2 kV/mm) of BST/ABS-0.6PVDF were enhanced with BST content increasing from 10 to 40 vol%, while a low dielectric loss was maintained (~ 0.09 at 1 kHz). BST/ABS-0.6PVDF with 40 vol% of BST exhibit a tunability of 20% at 16 kV/mm which doubles the commonly reported values and provides great promises for the dielectric devices such as phase shifter, tunable capacitors, and tunable antenna.

Gelcasting is a method which allows for the production of high-quality ceramic-metal composites. In this work, the problem of local polymerisation in gelcasting of alumina-tungsten composite and metal influence on activation energy of glycerol monoacrylate was investigated. The broadband dielectric spectroscopy method was used for the first time to study the kinetics of gelation in ceramic processing. Polymerisation reaction rates constant of pure monomer, and monomer with ceramic and the metal filler, within the temperature range from 313 K to 333 K were determined. The obtained results were compared with rheological measurements. The calculated activation energy of polymerisation for monomer with 0.5 vol% of tungsten is 66 kJ/mol in comparison to a pure monomer which is 290 kJ/mol. This indicates the catalytic influence of metal on the polymerisation. Therefore, in the alumina suspension with tungsten polymerisation begins near the surface of the metal particles resulting in polymer structure inhomogeneity and lower mechanical properties of green bodies.

The paper presents the thermal decomposition of the new, highly efficient organic additives used in colloidal shaping of ceramics, that is lactobionic acid (LAc), galacturonic acid (GAc) and diglyceryl acrylate (DGA). The sugar acids are effective deflocculants, especially for nanopowders, while DGA is the new monomer dedicated to gelcasting process. Most organic additives are indispensable in shaping step but must be then eliminated in order to obtain pure ceramic phase. The DTA/TG measurements coupled with mass spectrometry allowed to determine the thermal decomposition of organic compounds and observe type of gasses released to the atmosphere during heating. Additionally, the influence of the analyzed substances on the properties of selected ceramic suspensions and sintered bodies has been discussed. The new compounds have been examined in the preparation of ZTA (zirconia toughened alumina) composites by gelcasting, slip casting and subsequent sintering. The rheological behaviour of Al2O3-ZrO2 suspensions as well as selected properties (Vickers hardness, fracture toughness and microstructure) of sintered ZTA samples are presented.

This paper presents results of broadband dielectric spectroscopy studies in the composite system for which particularly strong interactions between polyvinylidene difluoride (PVDF: ferroelectric polymer,TC= 453−473 K) matrix and barium strontium titanate (BST) ferroelectric micro-particles can be expected. For PVDF the super-Arrhenius (SA) dynamics, associated with segmental motions freezing at the glass temperatureTg= 235 K, is evidenced. The addition of BST particles qualitatively changes dynamics, converting the SA-type behaviour in PVDF to the clear Arrhenius one in BST/PVDF composite. The latter crossovers to the relaxor-type SA dynamics on cooling, exactly at the glass temperature of PVDF. The preliminary model explaining such unique behaviour is proposed. For the consistent portraying of the SA evolution of primary relaxation times in PVDF and BST/PVDF, the activation energy index analysis was carried out and the new equation, entropy and symmetry controlled, is introduced. Studies are accomplished by the analysis of the ferroelectric-paraelectric transition in PVDF and for the composite system. They led to the discovery of the strong pretransitional anomaly ofdε∕dT, extending even to the vicinity of the room temperature, The semi-discontinuous nature of melting in PVDF and its composites, with the discontinuity metric △T≈ 20 K is suggested.Graphical abstract

The regional distribution of fillers can change the distribution of electric field in the ceramic/polymer composites and further affect the dielectric properties. Here, Ba0.6Sr0.4TiO3/PVDF (BST/PVDF) monolayer and its two kinds of sandwich-structural composites, PVDF-BST/PVDF-PVDF (PBP) and BST/PVDF-PVDF-BST/PVDF (BPB), were fabricated using solution casting method combined hot pressing process. The results showed BPB structural composite possesses the best dielectric performances with a relative permittivity of 17.3, an energy density (Ue) of 10.54 J/cm3 which is 2 times of BST/PVDF monolayer composite with the same BST content, as well as a dielectric tunability of 83.33%. Finite element simulation further proves that sandwich structure, especially BPB structure, can reduce the occurrence of electrical breakdown in the composite, and improve the energy storage characteristics and dielectric tunability. This work gives new thinking for the development of energy storage thin-film composites.

One of the important aspects in the preparation of composite materials is the possibility of reaction between used components. In the case of composite of ZrO2–Ti system, it could be the reaction between zirconia and titanium particles during sintering process. In this work ZrO2/Ti interface at 3Y-ZrO2–10 vol.% Ti composites was analyzed. The composites were prepared by slip casting method. Sintering process was carried out at 1450°C in the inert atmosphere of argon. The sinters were prepared for SEM and STEM microscope observations by polishing and ion milling. The chemical analysis was conducted by EDS. The bonding between Ti particle and ZrO2 matrix was continuous. XRD analysis, microscopic observations and chemical analysis showed the limited diffusion between components. The creation of new phases at ZrO2/Ti interface was not revealed.

The centrifugal-slip casting method was used for producing the Al2O3-Ni composites with a gradient distribution of the Ni phase. The final products had the shape of hollow cylinders. The casting slurries were water-based and contained alumina and nickel powders with two different particle sizes. The cast samples were then subjected to sintering at a temperature of 1400 °C in an N2/H2 reducing atmosphere with heating and cooling rates of 1 °C/min, and the dwell time - 4 h. The rheological properties of the water-based slurries were examined. It appeared that the presence of the Ni particles strongly affected the slurry properties which was probably associated with the strong interactions between the Ni and α-Al2O3 particles. The Al2O3-Ni composites with a gradient distribution of the Ni particles were examined using the X-ray diffraction method. No new phases such as the nickel aluminate spinel were identified in the sintered composites. The microstructure of the samples was analyzed using Scanning Electron Microscopy (SEM). The observations revealed that the samples were composed of three zones with different distributions of the Ni particles on their cross-section. Finally, the Ni particle distribution in the functionally graded materials was described quantitatively.

The paper concerns the synthesis and the characterization of new water-thinnable binder such as poly(acrylic–styrene) with the addition of a new amphiphilic macromonomer and it application in shaping of unmodified and modified (by silanization) Al2O3 by die pressing. The organic additives decomposed thermally to non-toxic gases which is beneficial from ecological point of view. Thus, the careful thermal analysis of synthesized binder was done. To characterize the synthesized binder, the glass transition temperature, wetting angle and diameter of polymer particles size in water were also measured. In the next step of the work, the density, porosity, tensile and bending strength, and microstructure observations have been done for modified and unmodified Al2O3 samples obtained by die pressing. The results confirmed that the synthesized binder is eco-friendly, because it decomposed to non-toxic gases such as carbon dioxide and water vapor during heating up to ca. 527 °C. The synthesized binders are characterized by low glass transition temperatures 5.6 °C and − 0.5 °C which are much lower than that of PVA (42 °C). It provided the high tensile strength (0.22 ± 0.01 MPa) of green bodies, 57% higher than strength of bodies with commercially available PVA and bending strength around 192 MPa. Density of sintered samples was around 95% of TD. Nevertheless, the best results were obtain for bodies based on modified Al2O3 where tensile strength of green bodies and bending strength of sintered samples were 0.30 ± 0.04 MPa and 237 ± 19 MPa, respectively.

This paper reviews recent developments and challenges of (Ba,Sr)TiO3/polymer functional composites. The microstructure of barium-strontium titanate (Ba,Sr)TiO3(BST)/polymer composites with different polymer matrices and the nature of the interface between the BST and polymer matrix is critical in the final dielectric properties. The effects of concentration, particle size and BST filler shape on the dielectric properties of BST/polymer composites are discussed. A theoretical model for the dielectric constants of ceramic/polymer composites and the fabrication of BST/polymer composites are described briefly. The development of a dielectric tunability for the BST/polymer composites is summarized. A dielectric tunability theoretical model is proposed based on our previous research results and the effects of several factors on the dielectric tunability of the composites are discussed, which contributes to a prediction of the dielectric tunability of the composites and provides important theoretical and research significance for future work.

The dilatometric and thermogravimetric methods were used to investigate the sintering conditions of 3Y–ZrO2 and 3Y–ZrO2–Ti composites. For the materials preparation, the nanometric zirconia stabilized by 3 mol% Y2O3 powder and micrometric titanium powder (3 and 10 vol%) were used. The green body samples were formed by slip casting method. The morphology of samples microstructures was determined by SEM observations. The stereological analysis of zirconia and zirconia–titanium composites was carried out using computer program. The density was measured using the Archimedes method. The hardness of sinters was also investigated. Addition of Ti into ZrO2 influenced the sintering behavior and thermal expansion of obtained composites. The analysis of the sintering process and characteristic temperatures confirmed the increase of onset and final temperature of shrinkage with the increase in Ti content. The changes of the thermal expansion curves for the pure zirconia and 3Y–ZrO2–Ti composites were the result of the αTi → βTi transformation and the transition temperature of the zirconia m → t transformation. The zirconia and composite samples were characterized by relative density about 98%, close to theoretical density. The slight growth of zirconia grains was observed.

The influence of expanded graphite (EG) on the thermal and rheological properties of shear thickening fluids (STF) based on silica powder with poly (propylene glycol) matrix was studied. Capturing the benefits of this non-Newtonian system in a fabricated material allows producing advance flexible protectors. However, in order to provide high protection potential in response to an external force, it is necessary to minimize negative effect of temperature on STF. The doping additives reduce the unfavorable effect of temperature increase on shear thickening flow during an impact through faster heat exchange and return to the initial state, characterized by the highest protective potential. EG in different volume fractions (0.10% - 5.00%) as a partial substitution of STF and SiO2 was added to studied systems and measured at temperatures in the range from 25.0 to 50.0°C. The dilatant effect of fluids increased by 580% for 5% volume fraction EG at 50.0°C.

This paper presents a study on the influence of hydroxyl groups and oxygen atoms together with chain length and branching of carrier fluid on the rheological and electrokinetic properties of shear thickening fluid (STF). An STF is non-Newtonian fluid behaviour in which the increase of viscosity increases with the applied shear rate. Ethylene glycol, triethylene glycol, 1,3-propanediol, glycerin, poly(propylene glycol) of different molecular weight and poly(propylene glycol) triol were used as the carrier fluids (dispersants). Silica powder with an average particle size of 100 nm was used as the solid phase. Zeta potential, particle size distribution (by DLS technique), steady-state and dynamic rheological measurements were conducted. Experimental results indicate that a different amount of hydroxyl groups and oxygen atoms together with chain length and branching of carrier fluids have a significant influence on the intermolecular interactions thereby and on the rheological properties of suspensions. Depending on the composition, it is possible to control rheological properties. The use of a suitable carrier fluid allows the required pattern flow to be obtained, from Newtonian through shear thinning to shear thickening, given specific shear conditions.

Results of broadband dielectric spectroscopy and rheological studies of poly(propylene glycol) + SiO 2 nanocomposites are presented. They show that the dynamics in high-concentrated composites is dominated by confinement and adsorption effects. The most notable finding is the impact of nanoparticles on fragility, the fractional translational – orientational decoupling and the shift of dynamics towards the pure Vogel-Fulcher-Tammann pattern, associated with the lack of local symmetry preferences.

Composite material with a gradient concentration of the metallic phase was prepared by the novel gel-centrifugal casting method. This method combines the consolidation of powders by the centrifugal force with the reaction of radical polymerization of an organic monomer which simultaneously proceeds within the composite slurry. The combination of the centrifugal casting with gel-casting permits production of ceramic–metal composites, including materials with a gradient distribution of metallic particles in a ceramic matrix. Special attention was paid to the thermal analysis of the composite Al2O3–Ni green bodies and the binder used in the fabrication of the material. The experiments were performed on the simultaneous thermal analyzer coupled with the mass spectrometer. The measurements were carried out in air and the inert atmosphere (argon) what allowed to determine the effects characteristic for organic binder decomposition and type of gases released to the atmosphere during thermal treatment. The measurements allowed also to establish the sintering program of the green composite samples and evaluate whether harmful gases are released to the atmosphere. The thermal experiments were complemented with physical and structural measurements, including X-ray diffraction and scanning electron microscopy.

Copolymers of N -isopropylacrylamide (PNIPAM) are one of the most promising microgel materials for medical applications, especially as a drug carrier. PNIPAMs present unique properties, such as size variation with changing pH and/or temperature. The results of a study on the uptake and release of a dye (Orange II) by microgels of N -isopropylacrylamide copolymer with 1-vinylimidazole (P(NIPAM-co-Vim) are presented. The dye was used as a model low-molecular substance. Hydrodynamic radius ( R h ) of P(NIPAM-co-Vim) particles was measured by dynamic light scattering as a function of temperature in two pH environments: acidic and basic. The dye particles contraction was monitored as a function of temperature at pH 4. The measurements of the zeta potential indicated a positive charge of P(NIPAM-co-Vim) particles at pH 4 and a negative one at pH 9. The key experiments were the internalization and the release of the dye. The effectiveness of this process was measured by UV-Vis spectroscopy on the supernatant derived from centrifuged P(NIPAM-co-Vim) suspension. At room temperature the efficiency of trapping of the dye by the microgel at pH 4 was 87%. Changing pH of a sample initially saturated with the dye from 4 to 9 led to a complete release of the trapped dye.

The paper presents the analysis of thermal stability and decomposition of Al2O3 and (Ba,Sr)TiO3 green bodies as well as commercially available organic additives which are used in shaping of ceramics by colloidal processing. The first analyzed ceramic material was Al2O3 green body obtained by gelcasting. The second examined material was elastic ceramic–polymer composite based on ferroelectric powder Ba0.8Sr0.2TiO3 with NiO obtained by tape casting method. This flexible and durable material is characterized by high value of dielectric constant and finds the application in devices operating at very high frequencies up to sub-THz. Most organic additives are indispensable just in forming step but must be then eliminated in order to obtain pure ceramic phase, additionally some of them have to be stable in a wide temperature range. The analyzed organic substances were as follows: 2-carboxyethyl acrylate, SYNTRAN 8250, DURAMAX D-3005, DURAMAX B-1000. The DTA/TG measurements coupled with mass spectrometry allowed to gain new knowledge concerning degradation of selected organic additives, thermal stability of ceramic–polymer composite and type of gases released from samples during thermal treatment.

Abstract. This report presents the results of high-pressure and broadband dielectric spectroscopy studies in polyvinylidene difluoride (PVDF) and barium strontium titanate (BST) microparticles composites (BST/PVDF). It shows that the Arrhenius behaviour for the temperature-related dynamics under atmospheric pressure is coupled to Super-Arrhenius/Super-Barus isothermal pressure changes of the primary relaxation time. Following these results, an explanation of the unique behaviour of the BST/PVDF composite is proposed. Subsequently, it is shown that when approaching the GPa domain the negative electric capacitance phenomenon occurs. Graphical abstract

Graphene aerogel/PVDF (GA/PVDF) composites with a three-dimensional structure were prepared using a vacuum-assisted impregnation process. The phase structure, morphology and piezoelectric properties have been systematically studied. The results show that GA/PVDF composites have good piezoelectric output characteristics and can provide corresponding feedback according to the magnitude and frequency of the acting force. When the PVDF concentration is 80 mg/mL, the GA/PVDF composite reaches the highest piezoelectric constant (d33 = 16 pC/N). The average peak output current is approximately 0.51 μA and shows good stability under repeated pressing. It is promising to apply to the field of flexible pressure sensors that can be self-powered.

Ceramic – metal composites are widely used materials in a whole world. There were invented many fabrication methods for those kind of materials, but still exists some problems which need to be fixed. Stability of high density metal particles (e.g. W, Mo, Nb) in ceramic-metal composite suspensions is one of crucial issues to be solved in order to obtain homogenous composite material with desired properties such as high fracture toughness, mechanical strength, hardness, wear resistance.In this paper, results of two different methods of stabilizing W particles in Al2O3– W – H2O system were compared. The zeta potential by laser doppler electrophoresis, stability by static multiple light scattering and rheological behavior of prepared suspensions were analyzed. As a result application of hetero-flocculation effect was consider as a good way to obtain homogeneous dispersion of metal particles with a high density.

The paper presents the application of 2-carboxyethyl acrylate as a new monomer in gelcasting of alumina. The research showed that the use of 2-carboxyethyl has a positive influence on the properties of green bodies, limiting the negative effect of oxygen inhibition. Oxygen inhibition which hampers polymerization reaction is a well known negative phenomenon in gelcasting but still not fully overcome for samples formed in air atmosphere. As a reference monomer 2-hydroxyethyl acrylate was used in the research. Rheological behavior of alumina suspensions containing both monomers has been studied, as well as the properties of green and sintered bodies obtained by gelcasting have been measured. The differences in the rheological properties and thus ceramic-monomer interactions in the slurries has been analyzed. The high values of densities and mechanical strength, accompanied with the pictures of microstructures of sintered ceramic parts have been presented, as a result of a successfully completed gelcasting process of alumina powder.

Slip casting is one of the most popular shaping method in ceramic technology which allows producing a large number of elements in small period of time. This shaping technique gives a possibility to fabricate ceramic or composite materials such as ZrO2-Ti. Ti with its properties (low density, high melting point, high-temperature strength, good corrosion resistance and others) combine with ZrO2 (high flexure strength, high compression resistance and very high KIC) can be considered for different applications as constructional and functional materials. For the preparation of such composite nanometric zirconium oxide powder stabilized by 3 mol% Y2O3 and micrometric titanium powder were used. Water-based slurries with 35, 40, 45 and 50 vol.% solid phase content were prepared with 3, 10 and 15 vol.% addition of titanium powder. Zeta potential and pH of prepared slurries were considered. The pH changes were tested as a function of Ti content. The viscosity of the prepared slurries was measured. The sedimentation tests for selected slurries were performed. The casting rate for slurry of 35% solid phase with 10 vol.% Ti was examined. These measurements showed good stability of slurries. With the increasing of the solid phase concentration the density of the green bodies increased. However, the increase of the content of Ti powder reduced the density of green body samples. For selected samples the SEM observations was carried out. Composites produced by slip casting were characterized by a homogenous distribution of Ti particles in the ZrO2 matrix.

The effect of molecular structure of d -galactose, d -mannose, d -glucose, 2-deoxy- d -glucose and 3-O-methyl- d -glucose on the viscosity of aqueous alumina nanoparticle suspensions was investigated by rheological measurements. The viscosity was found to be dependant on the molecular structure of these hexopyranoses. The research reveals that the orientation of primary and quaternary hydroxyl groups in a pyranose ring plays a crucial role in dispersing properties of monosaccharides. Moreover, the most important is the mutual orientation of these hydroxyl groups. Monosaccharides with axial and equatorial orientation of hydroxyl groups at first (C 1 ) and fourth (C 4 ) carbon atom in pyranose ring decrease the viscosity more than monosaccharides with two axial hydroxyl groups in these positions. Due to the differences in molecular structure of saccharides resulting in different shape of molecules and different compatibility to the water structure, the saccharides differ in ability to disturb water layers around alumina particles.

The aim of the current paper is to present the development of the method used for fabricating highly textured α -alumina elements. The experimental procedure described is based on a combination of two techniques: gelcasting is used in tandem with high magnetic field exposure. In the element shaping process, a new, low-toxic and environmentally friendly gelating system was implemented that is based on in situ polymerisation of an acryloyl derivative of galactose. Here, care was taken to achieve a highly textured structure of elements gelcast from the ceramic slurries of high solid contents (45–50 vol%), which have not been processed successfully for magnetic field alignment before. A secondary aim of the study was to investigate the combined effect of magnetic field exposure duration and the idle time of polymerisation on the effectiveness of the alignment. In the course of the experiment, high degrees of crystalline orientation of the gelcast samples were obtained ranging from 0.92 to 0.96, developed after the subsequent sintering at 1600 °C (the parameters were calculated on the basis of XRD pattern of the surface perpendicular to the magnetic field direction). The microstructures of the obtained elements are described in detail at the end of the paper, in a stereological analysis.

Monodisperse Ba0.6Sr0.4TiO3 hollow spheres (HS-BST) with good spherical morphology, uniform size and accurate proportion of Ba/Sr were systhesised using a novel template-assisted method. The particle size and shell thickness of HS-BST particles were adjusted by controlling synthesis conditions, including carbon sphere size, reactant concentrations, reaction time and temperature, as well as the content of hydrolytic inhibitor. The surface morphology of HS-BST could be improved by the addition of appropriate hydrolytic inhibitor (triethanolamine, TEA), as it could reasonably control the diffusion of metal ions and prevent problems such as BST coating uniformity caused by improper hydrolysis rates. The accurate proportion of Ba/Sr was obtained with the presence of hydrolytic inhibitor. The facile synthetic approach would provide a new insight into the design and fabrication of hollow spheres of other perovskite oxides.

Platelet PbBi4Ti4O15 (PBIT) microcrystals were fabricated by molten salt methods using different TiO2 crystal forms (anatase and rutile) as the reactants. The results showed that the pure PBIT phase can be obtained by using rutile as the reactant, while the PBIT and TiO2 phases coexisted when using anatase as the reactant. In comparison to anatase, the co-topping connection of rutile has better stability and accelerates the nucleation growth rate in a molten salt environment. Thus, PBIT microplatelets with the good crystallinity and plate-like morphology (aspect ratio of ~27) can be obtained when rutile is used as the reactant. Specifically, when using rutile as the reactant, a maximum d 33 ∗ of ~153 pm/V can be obtained, which may potentially allow the fabrication of anisotropic perovskite templates for textured ceramics.

Plate-like Ba0.6Sr0.4TiO3/Poly (vinylidene fluoride - trifluoroethylene -chlorotrifluoroethylene) (P-BST)/P(VDF-TrFE-CTFE) functional composite films were prepared via a tape casting method. All samples have textured microstructure, and the orientation degree of the composites is above 50%. Though pure terpolymer has a low dielectric permittivity (20.4) and a high loss (0.52), the introduction of ceramic particles can effectively enhance its permittivity as well as decrease the loss. The composite filled with 40 vol% ceramic fillers showed a high permittivity of 88.3 as well as a low loss of 0.056 accompanying with a high dielectric tunability about 30%. Additionally, the dielectric tunable theoretical model of the composite was investigated. The functional relationship between phenomenological coefficient ratio β1/β2 and the ceramic content was obtained. The final results indicate that the value of β1/β2 is inversely proportional to the ceramic phase content, as opposed to the composites matrix's dielectric constant which cannot be tuned by the electric field.

The previtreous dynamics in the glass-forming monomer, glycerol monoacrylate (GMA), was tested using the broadband dielectric spectroscopy (BDS). The measurements revealed a clear dynamic crossover at the temperature $ T_{B} = 254$ K and the time scale $ \tau (T_{B}) = 5.4$ ns for the primary (structural) relaxation time and no hallmarks for the crossover for the DC electric conductivity $\sigma_{DC}$ . This result was revealed via the derivative-based and distortions-sensitive analysis $ \mathrm{d} \ln H_{a}/\mathrm{d} (1/T)$ vs. $ 1/T$ , where $ H_{a}$ stands for the apparent activation energy. Subsequent tests of the fractional Debye-Stokes-Einsten relation $ \sigma_{DC} (\tau_{\alpha})^{S} = \mbox{const}$ showed that the crossover is associated with $ S = 1$ $ (\mathrm{for}\ T > T_{B}) \rightarrow S = 0.84$ (for $ T < T_{B}$ . The crossover coexists with the emergence of the secondary beta relaxation, which smoothly develops deeply into the solid amorphous phase below the glass temperature $ T_{g}$ .

The controlled development of texture in ceramics allows to improve some electrical, piezoelectric and mechanical properties of advanced ceramics materials by tailoring the microstructure. A highly textured microstructure of undoped dense alumina was attained by applying a novel combination of gelcasting techniques with magnetic alignment followed by sintering. A newly synthesized low-toxic acrylic monomer based on galactose was introduced to the gelcasting procedure. Thermal analysis of the gelcast has been performed to examine decomposition process of the new binder and match appropriate sintering rate. The effectiveness of the proposed procedure has been related to rheological properties of the suspension by clarifying the influence of the powder and the dispersant content. It has been also related to the idle time of polymerization by clarifying the influence of the initiator content. The new method is compared to slip casting in high magnetic field that has been used widely so far.

The article presents the interdisciplinary research among organic synthesis, chemistry of polymers and ceramic technology. It presents the synthesis of monoacryloyl esters of fructose and glucose that is 1-O-acryloyl-D-fructose and 3-O-acryloyl-D-glucose, conditions of their polymerization and application in shaping of advanced ceramic powders by the so called gelcasting method. The paper presents the influence of carbohydrate esters on the viscosity of Al2O3 suspensions and microstructure of final ceramic samples. The results showed that synthesized esters of saccharides can play the role of organic monomers able to polymerize in situ and self-cross-linking compounds in gelcasting. The paper presents the proposed structure of polymeric network which is formed from acryloyl ester of glucose during gelcasting process. The paper describes rheological behaviour of slurries composed of synthesized substances and A2O3 powders, wetting angles of alumina substrate by synthesized compounds, differences in glass transition temperatures of polymers and the microstructure of obtained final ceramic samples.

The aim of the work was to study a use of an acryloyl derivative of glycerol (glycerol monoacrylate), as a low-toxic, water soluble monomer in shaping of ZrO2 by using the in situ polymerization. The derivative was synthesized by the authors in a one-step synthesis. The work presents an interdisciplinary research in polymer chemistry and ceramic technology showing, how the properties of the system monomer/polymer influence the properties of zirconia green bodies. The wetting angle, glass transition temperature and polymeric shrinkage of the synthesized compound were measured at first. Then the zeta potential and rheological properties were measured to characterize the zirconia slurries. Ceramic green bodies were obtained by gelcasting through in situ polymerization of glycerol monoacrylate. The density, porosity and tensile and bending strengths were then measured, and thermal analysis and microstructure observations were performed for zirconia samples. The results have confirmed that glycerol monoacrylate provides a good homogeneity and high mechanical strength of ZrO2 samples both before and after sintering (749 MPa). The density of the sintered samples was around 99% of TD. The polymer is characterized by a very low glass transition temperature (−61 °C). It means that it is elastic at room temperatures, what positively affects the tensile strength of green bodies. The research has shown that the acryloyl derivative of glycerol is a good alternative for commercially available acrylic monomers used in shaping of zirconia by gelcasting.

The paper reports the development of a new system applicable in shaping techniques using in situ polymerization. The system is based on saccharides derivatives and allows to eliminate harmful processing agents from ceramic slurry. Instead of commonly applied 2-hydroxyethyl acrylate or acrylamide (monomers) and N,N,N′,N′-tetramethylethylenediamine (activator) the compounds based on glucose were used. As a monomer 3-O-acryloyl- d -glucose was applied. As a new activator l -ascorbic acid (also known as vitamin C) was used. Research was carried out for YSZ. As initiators ammonium persulfate and hydrogen peroxide were used. The new system was studied in terms of zeta potential, pH and rheological measurements. Ceramic samples were prepared by gelcasting and gel-tape casting methods. The experiments showed that l -ascorbic acid used as the activator has positive influence on rheological properties of suspensions with YSZ and together with ammonium persulfate allows to form defect free ceramic bodies with a homogenous composition.

The main objective of producing ceramic-metal composites is to improve the fracture toughness of the brittle ceramic matrix. Classical methods of powder metallurgy (such as isostatic or uniaxial pressing) are not capable of fabricating complex-shape elements. For this reason, colloidal processes have been applied recently in manufacturing of ceramic matrix composites. In the present work, Al2O3–3 vol.% Ni composites were prepared by aqueous gelcasting process and sintering in reducing atmosphere. The commercially available monomers 2-hydroxyethyl acrylate and N,N′-methylenebisacrylamide as cross-linking agents were used. The activator was N,N,N′,N′,-tetramethylenediamine (TEMED) and ammonium persulfate was added as an initiator of the polymerization process. Composite slurries were obtained from alumina powders (grain size 0.21 μm) and 3% (in respect to the total solid volume) of two nickel powders of different grain size (~10 and ~0.4 μm). The paper describes the rheological properties of the obtained composite slurries. The properties of green and sintered elements have also been presented. It was found that the presence of nickel particles had a significant influence on the slurry polymerization process. The green and sintered relative density was in every case higher than 57 and 97%, respectively.

Podążając za trendem „zielonej chemii", zakładającym m.in. wykorzystywanie nietoksycznych i odnawialnych surowców w technologii, zaprojektowano i zsyntezowano nowy monomer przeznaczony do zastosowania w procesie odlewania żelowego. Wyjściowym substratem trójetapowej syntezy był ksyłitol, a finalnym produktem 1-O-akryloiloksylitol. Otrzymana pochodna została sprawdzona pod względem efektywności polimeryzacji in situ w ceramicznej masie lejnej na bazie tlenku glinu. Zbadano jej wpływ na właściwości neologiczne stosowanych zawiesin. Odlano serie kształtek, dla których wyznaczono podstawowe parametry w stanie surowym oraz p|j spiekaniu. Wyniki porównano stosując równolegle komercyjnie dostępny monomer akrylan 2-hydroksyetylu.

W niniejszej pracy przedstawiono wyniki badań dotyczące wpływu rozkładu wielkości ziarna na właściwości zagęszcza- nia ścinaniem. Fazę stałą stanowiła mieszanina nanokrzemionki o średnich wielkościach ziarna 7 i 200 nm, gdzie stosunek nanokrzemionki 200 nni do nanokrzemionki 7 nm wynosił odpowiednio 95:5. 90:10, 85:15, 80:20, 75:25 i 50:50. Jako ciecz dyspergującą zastosowano glikol polipropylenowy o masie molowej 425 g/mol. Badania reologiczne lepkości w funkcji wzrastającej szybkości ścinania wykonano za pomocą reometru rotacyjnego Kinexus Pro w układzie płytka-płytka. Szybkość ścinania zmieniała się od 1 do 1000 s"1. Wyniki przeprowadzonych badań pokazały, że poprzez częściowe zastąpienie nano- krzemionki 200 nm nanokrzemionką 7 nm możliwe jest przesunięcie początku zagęszczania ścinaniem w stronę wyższych szybkości ścinania, jednakże skok dylatancyjny obniża się. W ramach pracy zbadano również wpływ rozkładu wielkości ziarna na maksymalne stężenie fazy stałej. Maksymalne stężenie fazy stałej wyniosło 35%obj.

Water leaching procedure was successfully applied for modification of surface properties and improvement of sinterability of commercial nano-ZrO 2 . It has been shown that the process effectively removes some ionic impurities thus influencing the compositional, electrokinetic and acidic/basic properties of nanozirconia surface. The process purifies the surface and improves the deflocculation susceptibility of nano-ZrO 2 if d -fructose is used as a dispersant. The studies revealed that by using a purified powder, it is feasible to obtain green and sintered samples of satisfactory densification and microstructural features. SEM micrographs of polished sintered bodies have provided some evidences that homogeneous and fully densified microstructure of the samples can be obtained by using water-leached nanozirconia powders.

Aluminum nitride was found to be of great significance in advanced ceramics. A widely applicable semiconductor, AlN is also commonly known for its considerable heat conductivity, as high as 320 W/(m·K). The idea behind the studies was to use AlN dispersions as a heat transferring liquid in closed systems. Such a liquid heat-carrier should give a proper rheological response when under variable shear-temperature conditions. Contrary to other systems reported in literature, i.e. nanofluids [1–20], the systems presented consisted of AlN micropowder and some novel base liquids: poly(propylene glycols) with an average molecular weight of 425 and 2000. The optimal result was to produce dispersions which display Newtonian-like flow at increased temperature and shear rate, as well as a suitable AlN concentration with sustained time-stability. This compilation of research assumptions should result in intensified heat exchange capabilities of liquid transferring media made on the basis of aluminum nitride.