The nanocomposites based on water glass matrix were attempted in the study. Nanoparticles of ZnO, Al2O3 or MgO in organic solutions

were applied into water glass matrix in the amounts of: 1.5; 3; 4 or 5 mas. %. Wettability of the quartz sad by the nanocomposites based on

water glass matrix was determined by testing changes of the wetting angle θ in time τ for the system: quartz – binder in non-stationary

state, by means of the device for measuring wetting angles. Wettability measurements were carried out under isothermal conditions at an

ambient temperature (20 – 25 oC). The modification improves wettability of quartz matrix by water glass, which is effective in improving

strength properties of hardened moulding sands. Out of the considered modifiers in colloidal solution of propyl alcohol water glass

modified by MgO nanoparticles indicated the smallest values of the equilibrium wetting angle θr. This value was equal app. 11 degrees and

was smaller no less than 40 degrees than θr value determined for not modified water glass. Viscosity η of nanocomposites based on water

glass matrix was determined from the flow curve, it means from the empirically determined dependence of the shearing stress τ on shear

rate γ: τ = f (γ) (1), by means of the rotational rheometer. Measurements were carried out at a constant temperature of 20 oC. The

modification influences the binder viscosity. This influence is conditioned by: amount of the introduced modifier as well as dimensions and

kinds of nanoparticles and organic solvents. The viscosity increase of the modified binder does not negatively influence its functional

properties.

Oxide fiber-reinforced Ni-base composites have long been considered as attractive heat-resistant materials. After several decades of active research, however, interest in these materials began to decline around mid-1990’s due chiefly to 1) a lack of manufacturing technology to grow inexpensive single-crystal oxide fibers to be used in structural composites, and 2) fiber strength loss during processing due to chemical interactions with reactive solutes in the matrix. The cost disadvantage has been mitigated to a large extent by the development of innovative fiber fabrication processes such as the Internal Crystallization Method (ICM) that produces monocrystalline oxide fibers in a cost-effective manner. Fiber strength loss has been an equally restrictive issue but recent work has shown that it may be possible to design creep-resistant composites even when fiber surface reconstruction from chemical interactions has degraded the strength of extracted fibers tested outside the matrix. The key issue is the optimization of the composite- and interface structure. Reaction-formed defects may be healed by the matrix (or a suitable coating material) so that the fiber residing in the matrix may exhibit diminished sensitivity to flaws as compared to fibers extracted from the matrix and tested in isolation of the matrix. Generally, the Ni-base/Al2O3 composites exhibit acceptable levels of wettability and interface strength (further improved with the aid of reactive solutes), which are required for elevated-temperature creep-resistance. In order to harness the full potential of these composites, the quality of the interface as manifested in the fiber/matrix wettability, interface composition, interphase morphology, and interface strength must be designed. We identify key issues related to the measurement of contact angle, interface strength, and chemical and structural properties at the fiber/matrix interface in the Ni/alumina composites, and present the current state-ofthe-art in understanding and designing the Ni/alumina interface. There should be no doubt that optimization of the interface- and composite microstructure through judicious control of the fabrication process and surface modification shall yield technologically promising Ni-base/oxide fiber composites.

Selective Laser Melting (SLM) is a modern manufacturing method with many applications in medicine, aerospace and automotive industries. SLM processed materials are characterized by good dimensional accuracy and properties comparable or superior to materials obtained by traditional processing methods. In this paper an SLM process was used to obtain 316L stainless steel parts. This paper presents the microstructure, chemical and phase composition, physicochemical and electrochemical properties of 12 groups of tested samples, differentiated by the SLM processing parameters. Based on the investigation, it can be inferred that the selection of the appropriate SLM parameters is very important to determined final material properties. The samples produced with the energy density E = 600 J/mm3 were observed to possess optimum properties – a homogeneous structure, density closest to the desired one, good wettability and pitting corrosion resistance.

The production process of prosthetic restorations runs in two stages. In the first stage, the prosthetic foundation is produced of metal

alloys. In the second stage, a facing material is applied on the produced element. In both stages, the wettability is significantly important,

as well as the free surface energy relating to it. The quality of the obtained cast depends on the surface phenomena occurring between the

metal alloy and the material of which the casting mould is made. The performed examinations also point to a relation between the ceramics

joint and the base, depending on the wetting angle.

The aim of the presented paper was to examine influence of the composition of a Ti(C,N)-type coating on bases made of the Ni-Cr

prosthetic alloy on the wettability and the surface free energy.

The test material were disks made of the Ni-Cr alloy with the diameter of 8 mm. The disks were divided into five groups, which were

covered with Ti(C,N) coatings, with different amounts of C and N in the layer. In order to determine the surface free energy (����), the

wetting angle was measured. Two measure liquids were applied: distilled water and diiodomethane.

The obtained results of the measurements of the water-wetting angles suggest that together with the increase of the ratio of nitrogen to

carbon in the Ti(C,N) coating, the surface hydrophobicity increases as well. In all the samples, one can see a large difference between the

energy values of the polar and the apolar components. The high values of the polar components and the low values of the apolar ones make

it possible to conclude that these surfaces exhibit a greater affinity to the polar groups than to the apolar ones.

On the basis of the analysis of the surface free energy, one can state that covering the alloy with Ti(C,N)-type coatings should not decrease

the adhesion of the ceramics to the alloy, whereas TiC coatings should lead to the latter’s improvement. Due to their hydrophilicity, TiC

coatings should decrease the adhesion of bacteria to the surface and hinder the formation of a bacterial biofilm.

In this study, silicon carbide (SiC) reinforced lead-free solder (SAC305) was prepared by the powder metallurgy method. In this method SAC305 powder and SiC powder were milled, compressed and sintered to prepare composite solder. The composite solders were characterized by optical and scanning electron microscopy for the microstructural investigation and mechanical test. Addition of 1.5 wt. % and 2 wt. % ceramic reinforcement to the composite increased compressive strengths and microhardness up to 38% and 68% compared to those of the monolithic sample. In addition, the ceramic particles caused an up to 55% decrease in the wetting angle between the substrate and the composite solder and porosity was always increased with increase of SiC particles.

High temperature behavior of three compacted graphite iron (CGI) alloys on polycrystalline alumina substrates (99.7%, poro­sity <3%) were examined by the sessile drop method combined with classical contact heating procedure in flowing Ar. High-speed high-resolution CCD camera was used for continuous recording of the CGI/Al2O3 couples during melting alloy, heating to and holding the couples at the test temperature of 1450°C for 15 min and their subsequent cooling. The comparative studies were made with conventional CGI (in wt.%: 3.70 C, 2.30 Si, 0.44 Mn, 0.054 P, 0.017 Mg, 0.015 S) and two alloys additionally containing the same amounts of 0.25 Mo, 0.1 V, 0.045 Sn and 0.032 Sb with different concentrations of Mg + Cu additions, i.e. 0.01Mg + 0.33Cu and 0.02Mg + 0.83Cu. All three CGI alloys demonstrated non-wetting behavior on the Al2O3 substrates while the contact angle values slightly decreased with increase of the Mg + Cu content in the alloy, i.e. 131° (unalloyed CGI), 130° (0.01Mg + 0.33Cu) and 125° (0.02Mg + 0.83Cu). Structural characterization of solidified couples by light microscopy and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy revealed: 1) heterogeneous nucleation of discontinuous graphite layer at the drop-side interfaces and on the surface of the drops; 2) reactively formed Mg-rich oxide layer at the substrate-side interface; 3) the formation of satellite droplets on the surface of the drops during their solidification; 4) degeneration of initially compacted graphite to lamellar graphite after remelting and subsequent solidification of the drops, particularly in their surface layer.

The aim of the present study was to develop a modifier for water glass. The method of thermal generation of metal oxide nanoparticles was adapted and used in the research. Nanoparticles of ZnO from the thermal decomposition of basic zinc carbonate were used. A method for the modifier introduction was developed, and the effect of modifier content and organic solvent type on the physico-chemical properties of binder (viscosity) and quartz wettability was determined. Binder viscosity was examined from the flow curves plotted with the help of a RHEOTEST 2 rotational rheometer equipped with proper software. Quartz wettability was determined examining timerelated changes in the value of the contact angle in a quartz-binder system, until full stabilisation of the angle value has been achieved. Binder modification was carried out on sodium water glass designated as R"145". The water glass modifiers were suspensions of ZnO nanoparticles in propanol and methanol at a fixed concentration of c = 0.3 M and with the size of nanoparticles comprised in a range of <61 - 981 nm>. Water glass modification with the suspensions of ZnO nanoparticles in methanol and propanol showed the effect of modifier on the water glass viscosity and quartz wettability. This effect depends on the type of alcohol used. The ZnO suspension in propanol (alcohol with a longer hydrocarbon chain) affects more strongly the viscosity of binder and quartz wettability than the methanol suspension.

The pool boiling characteristics of dilute dispersions of alumina, zirconia and silica nanoparticles in water were studied. These dispersions are known as nanofluids. Consistently with other nanofluid studies, it was found that a significant enhancement in Critical Heat Flux (CHF) can be achieved at modest nanoparticle concentrations (<0.1% by volume). Buildup of a porous layer of nanoparticles on the heater surface occurred during nucleate boiling. This layer significantly improves the surface wettability, as shown by a reduction of the static contact angle on the nanofluid-boiled surfaces compared with the pure-water-boiled surfaces. CHF theories support the nexus between CHF enhancement and surface wettability changes. This represents a first important step towards identification of a plausible mechanism for boiling CHF enhancement in nanofluids.