Dilatometric Method Research Articles

Research article on thermal evaluation of Al-Si3N4 composites using Machine Learning

Lightweight aluminium alloys are being rigorously researched for their growing industrial applications because of their significant property advantages and cost-effectiveness. This work focuses on producing novel composites based on the Al6061 alloy by adding reinforcement at different weight concentrations of 0, 3, 6, 9, and 12 % (silicon nitride) via liquid metallurgy stir casting. To determine the impact of reinforcing percentage on Al6061 alloy, the microstructure, EDS analysis, thermal conductivity and thermal expansion of these stir cast specimens were evaluated. Thermal conductivity was evaluated using a comparable cut bar method (ASTM E1225), whereas thermal expansion was determined using a push-rod dilatometer method (ASTM E228). From experimentation, it was observed that microstructure analysis of composite showed uniform distribution of Si3N4 micron particles with the smallest of porosities and agglomeration was observed. The formation of dendrite structure was observed in all composite specimens due to faster solidification. The thermal conductivity increased by 23.33 %, and the coefficient of thermal expansion decreased by 20.73 %. The thermal characteristics of Al6061 reinforced with Si3N4 micron particles were superior to those of Al6061 without Si3N4 reinforcement. Machine Learning models were used to predict the coefficient of thermal expansion and the thermal conductivity of Al 6061 composites. Different models were trained with the experimental datasets and the performance of each model was evaluated.

Thermodynamic prediction and experimental verification of phase transformation kinetics in 3Mn steel with Ti and V microadditions

AbstractIn this work, the phase transformation kinetics and precipitation processes were studied using thermodynamic calculations and a dilatometric method to determine the optimal chemical composition of medium-Mn steel and its initial parameters of heat treatment. The investigated steel is intended for forgings with the microstructure composed of bainitic matrix and retained austenite (RA). An influence of Al and Si on the Ms temperature was characterized to obtain the best chemical composition in terms of RA stabilization. Theoretical continuous cooling transformation (CCT) and time–temperature transformation (TTT) diagrams were determined and compared with dilatometric results. Microstructural observations were compared with the dilatometric results. The hardenability of steel was high due to increased Mn and Mo additions. A very small fraction of cementite is expected in the microstructure due to Al and Si additions. The shortest time to start and finish the bainitic transformation was noted for the isothermal heat treatment at 420 °C. The completion of the bainitic transformation took about 25 min and is acceptable from the industrial point of view. The obtained results constitute a good basis for designing thermomechanical processing routes of bainitic steels with RA.

Supercooled austenite transformations in a considerable steel for a special engineering products

The advantages, disadvantages and some features of a dilatometric method for studying the transformation of supercooled austenite in steels under continuous cooling are briefly discussed. The continuous cooling transformation diagram of the steel under consideration containing 0.50 wt. % C, 0.25 Si, 0.65 Mn, 0.75 Cr, 1.30 Ni and 0.15 Mo, respectively was plotted based on experimental data obtained upon dilatometer measurements carried out with dif-ferent cooling rates (0.1, 0.3, 1, 5, 30 K/s) on the Linseis L78 RITA dilatometer. According to the obtained dilatometer curves, the degree of transformation was calculated in accordance with the standard method, its disadvantages and possible ways to eliminate them are noted. Additionally for the proper design of the continuous cooling transformation diagram of supercooled austenite metallographic examination and hardness tests were carried out after various heat treatment modes. A qualitative description of the formed microstructures was performed in order to confirm the obtained dilatometer data. The “tangent method” was also employed to determine the critical temperatures upon heating at the rate of 0.1 K/s and the temperature of the of the martensite start temperature upon cooling from the austenitization temperature of 880 °C, based on the literature data the application of the implemented method is justified. Some recommendations are presented as possible methods for selecting the dimensions of parts for which the steel under consideration was planned to be used. Using the example of a billet with diameter of 50 mm, from which samples were machined for research, the possibility of practical application of one of the methods for determining the type of structures formed along the cross section of steel products under continuous cooling from the austenitic region is shown.

Supercooled austenite transformations in a considerable steel for a special engineering products

The advantages, disadvantages and some features of a dilatometric method for studying the transformation of supercooled austenite in steels under continuous cooling are briefly discussed. The continuous cooling transformation diagram of the steel under consideration containing 0.50 wt. % C, 0.25 Si, 0.65 Mn, 0.75 Cr, 1.30 Ni and 0.15 Mo, respectively was plotted based on experimental data obtained upon dilatometer measurements carried out with dif-ferent cooling rates (0.1, 0.3, 1, 5, 30 K/s) on the Linseis L78 RITA dilatometer. According to the obtained dilatometer curves, the degree of transformation was calculated in accordance with the standard method, its disadvantages and possible ways to eliminate them are noted. Additionally for the proper design of the continuous cooling transformation diagram of supercooled austenite metallographic examination and hardness tests were carried out after various heat treatment modes. A qualitative description of the formed microstructures was performed in order to confirm the obtained dilatometer data. The “tangent method” was also employed to determine the critical temperatures upon heating at the rate of 0.1 K/s and the temperature of the of the martensite start temperature upon cooling from the austenitization temperature of 880 °C, based on the literature data the application of the implemented method is justified. Some recommendations are presented as possible methods for selecting the dimensions of parts for which the steel under consideration was planned to be used. Using the example of a billet with diameter of 50 mm, from which samples were machined for research, the possibility of practical application of one of the methods for determining the type of structures formed along the cross section of steel products under continuous cooling from the austenitic region is shown.

Thermal and chemical expansion of layered oxygen-deficient double perovskites

Layered oxygen-deficient double perovskites (ODP) based on the rare-earth elements (REE), barium and 3d-metals (Fe, Co, Cu etc.) are characterized by high values of electrical conductivity and high electrochemical activity in oxygen reduction reaction, and are considered as prospective cathode materials for intermediate-temperature solid oxide fuel cells (SOFC) on the base of proton- and oxygen-ion conducting solid electrolytes (SE). Effective cathode materials should be thermomechanically compatible with materials of SE, which tаkes place when the values of their thermal expansion coefficients (TEC) are close to each other. Due to this the study of thermal expansion of ODP as well as the isotation of different contributions in it (thermal, chemical, spin etc.), is of considerable interest. In this work using dilatometric method the thermal expansion of NdBa1–xSrxFeCo0,5Cu0,5O6−δ (0.0 ≤ х ≤ 1.0) (NBSFCC) ODP was studied using dilatometric method. It was established that the values of average linear thermal expansion coefficient (LTEC) (α) of the samples sharply increased from (15.1–16.2) · 10–6 K–1 at Т < 630–920 K to (18.9–23.5) 10–6 K–1 at Т > 630–920 K due to the evolution of weaklybonded oxygen from the samples. Values of α in the low-temperature region increase with increasing of values of their oxygen nonstoichiometry index (δ), and in the high-temperature one increase with the x increasing due to the increment of chemical contribution in the samples expansion. Based of the results of dilatometry, thermogravimetry, and iodometry, the thermal and chemical contributions in the expansion оn NBSFCC were isolated, and the effect of crystal structure, cationic and anionic composition of NBSFCC ODP on the values of their thermal and linear chemical expansion coefficient (LCEC, αδ ) was investigated. It was found, that LCEC values of the samples sharply increased from (8.6–11.8) · 10–3 at (х < 0.5) to (12.6–15.8) · 10–3 at (х > 0.5) when transition from ordered tetragonal (х < 0.5) to disordered cubic (х > 0.5) phase took place. It was shown, that dependences of LTEC and LCEC of NBSFCC phases on their crystal structure and chemical compositions obtained in this work are in good accordance with the analogous dependences determined earlier for the ODP of other types.

Development and investigation of a porous metal-ceramic substrate for solid oxide fuel cells

The process of creating a porous metal-ceramic material based on Ni-Al alloy and gadolinium-doped cerium oxide (CGO) using the thermal explosion method has been investigated. This study aims to analyze the effect of CGO on the thermal explosion parameters and the architecture of the resulting Ni-Al-CGO materials. In this regard, the influence of adding CGO powder to the Ni-Al system on the synthesis process and structure formation during controlled heat loss thermal explosion has been studied. Dependencies of temperature and time characteristics of the thermal explosion on initial parameters have been measured. It has been demonstrated that the concentration of CGO in the initial mixture and heat dissipation from the sample significantly affect the rate of the exothermic reaction. The phase composition of the obtained porous materials, depending on the CGO content and the temperature of subsequent vacuum annealing, was analyzed using X-ray diffraction. The chemical composition and microstructure of the synthesis products were examined through electron microscopy and energy-dispersive X-ray spectroscopy. The possibility of forming metal-ceramic composites with a porosity of 60–65 % for use as supporting substrates for solid oxide fuel cells with a NiO/CGO anode has been shown. An anodic layer of NiO/CGO was applied to a metal-ceramic base of the composition (Ni+25 %Al)+5 %CGO using screen printing, which was then annealed in an air atmosphere at 1300 °C and reduced at 900 °C in a hydrogen atmosphere. The dilatometric method determined that adding 40 wt.% Cr to a mixture of Ni-Al powders reduces the average coefficient of thermal expansion of the new material.

The comparison of polymerization activity of typical cationic quaternary ammonium salt monomers

AbstractThe cationic water‐soluble polymers, which are widely used in many areas such as papermaking and separation process, are typically synthesized through polymerization of cationic monomers represented by quaternary ammonium salt. In this work, the polymerization reaction kinetics of three typical quaternary ammonium salt cationic monomers including acryloyl oxygen ethyl trimethyl ammonium chloride (DAC), methyl acryloyl oxygen ethyl trimethyl ammonium chloride (DMC), and methyl acrylamide propyl trimethyl ammonium chloride (MAPTAC) was examined by using the dilatometer method. The results showed that the polymerization rate of all three monomers increased with the increase of initiation temperature, monomer concentration, and initiator concentration. Under the same conditions, the polymerization activity of the three monomers followed the order: DAC > DMC > MAPTAC. The activation energies for the polymerization reaction under the specified conditions were EaDAC = 138.97 kJ/mol, EaDMC = 141.24 kJ/mol, and EaMAPTAC = 226.97 kJ/mol, respectively. The polymerization rate equations were RpDAC = k1[M]4.25[I]0.51, RpDMC = k2[M]3.77[I]0.50, and RpMAPTAC = k3[M]3.30[I]0.49. The polymerization activity of the monomers may be influenced by electronic effects and steric hindrance of the monomer structure. This work has provided a theoretical and experimental foundation for the actual work of structural design and preparation of cationic water‐soluble polymers.

Features of the Chromium thermal expansion in a wide temperature range

The thermal expansion of polycrystalline Chromium in the temperature range of 95–1673 K by the dilatometric method has studied. Critical indices and amplitudes of the thermal expansion coefficient in the magnetic phase transition are determined. The rapid growth of the linear thermal expansion coefficient at high temperatures is confirmed. The temperature dependences of the thermal properties were obtained, and the reference tables of the recommended values for a wide temperature range of a solid state were developed.

Experimental vs. Theoretical Viscosity Determination of Aluminosilicate Glasses.

The paper presents the results of studies on the viscosity of the glass mass in various temperature ranges, determining the basic technological parameter, very important from the point of view of melting and forming. For this purpose, six sets based on natural raw materials such as basalt, dolomite, and amphibolite, modified with different amounts of float glass cullet, were melted. The melting process was carried out in an electric furnace at the temperature of 1450 °C for 2 h. Using the dilatometric method, high-temperature microscopy and theoretical calculation methods, the viscosity of the produced glasses was determined in various temperature ranges. Comparative analyses of the employed methods were carried out. The significance of the applied calculation methods for aluminosilicate glasses depending on the basic chemical composition of the glasses was presented. The relationship between the manner of incorporating amphoteric ions Al3+, Fe3+ and Mg2+ into the glass structure and the change in viscosity in the temperature range corresponding to the working point range at 104 [dPa·s] viscosity and the relaxation range-Tg temperature at 1013 [dPa·s] viscosity was justified. It was justified that in order to plot the viscosity curve with the correct slope in the forming range for aluminosilicate glasses, it is appropriate to use the two-point method based on the fixed viscosity points of 104 [dPa·s] and 1013 [dPa·s].

Temperature and composition dependence of thermophysical properties within a wide temperature range for ternary Si–Ge–Ag alloys

The thermophysical properties of Si–Ge–Ag alloys in a broad temperature range are essential for the design of electronic devices. In this work, relationships between specific heat, thermal expansion, thermal conductivity and temperature, as well as chemical composition of Si–Ge–Ag alloys were clarified. Moreover, various thermophysical properties’ prediction strategies of multicomponent alloys from pure elements were evaluated. The specific heat of Ag–Si, Ag–Ge, Si–Ge, and Si–Ge–Ag alloys was determined by the differential scanning method. The results showed a significant increase with rising temperature at low temperatures followed by a gradual rise at high temperatures. The specific heat reached the maximum value when a small amount of Si/Ge was introduced to Ag. The coefficient of thermal expansion was obtained by a dilatometric method and increased slightly with the increasing temperature, while decreased linearly with the increase in the Si/Ge content. Furthermore, the thermal conductivity was investigated via a laser flash apparatus. It decreased with rising temperature when the Ag content is smaller than 50%, whereas it increased with rising temperature when the Ag content exceeds 50%. The thermal conductivity of Si–Ge alloys decreased with rising temperature and reached the local minimum for Si–Ge alloys with an equiatomic ratio of Si and Ge. More importantly, the experimental results reveal that the thermal expansion that is related to volume can be estimated approximately by pure metals in Si–Ge–Ag alloys. However, this rule cannot be applied to specific heat and thermal conductivity, which is due to the influence of lattice vibration, electronic scattering, and microstructure.

Study of cellulose additive effect on the caking properties of coal

Purpose. The work aims to study the effect of cellulose on the caking properties of various types of coking coal used in coking blends. The change in caking abilities has been analyzed to achieve the aim using standard techniques. At the same time, the effect of biomass additives on the plastic properties of coal has been analyzed comprehensively; the optimal amount of additive for practical purposes has been determined. Methods. Multiple coal characteristics in the plastic stage have been studied using a dilatometric method, the enhanced swelling pressure method, the plastometric method, and the Roga index test. The first three methods make it possible to characterize the caking properties of coal; and the Roga index test characterizes its coking ability. Findings. It has been identified that the optimal amount of biomass additive to study the effect on the properties of coal in the plastic state is more than 5 wt. %. In the paper, experimental dependences of the 5 wt. % cellulose addition influence on the caking properties of four coal grades have been obtained. The results showed a slight decrease in caking properties in terms of swelling, swelling pressure, thickness of the plastic layer, and caking ability. Simultaneously, the most sensitive methods for assessing the effect of cellulose addition on the coal plastic properties are the dilatometric method as well as the enhanced method for the swelling pressure determination. Originality. A comprehensive study of the effect of pure cellulose as a component of lignocellulose biomass on the properties of different coal grades in the plastic state (i.e. caking prperteis) has been carried out. A slight change in the coal properties in the plastic state with adding 5 wt. % cellulose, decreasing caking properties, has been shown. An important, not previously reported, conclusion is that the cellulose additive does not have any noticeable effect on the physical properties of the coal charge owing to its loose structure. Practical implications. A slight change in the caking properties of coal has been established with the addition of 5 wt. % which is of practical importance for the preparation of coal blends, and the coke production in the cases of using additives of lignocellulosic biomass without losing its quality. Additionally, renewable additive use while obtaining fuels and reducing agents is an approach to mitigate the negative environmental impact.

Analysis of the development of autogenous shrinkage of CEM I 42.5R and CEM III/A 42.5N cement pastes with different water to cement ratios

In concrete technology, cements with a high content of Portland clinker are increasingly being replaced by blended binders with a lower carbon footprint. Such binders include blastfurnace cements, which are successfully used in concretes designed for large-scale elements, self-compacting concretes, as well as for the precast concrete industry. Blast furnace cements exhibit lower strength gain relative to Portland cements and a lower heat of hydration. Composites that incorporate them are significantly more resistant to the occurrence of thermal stresses at the early stages of curing of concrete. This paper provides a comparative study of the development of autogenous shrinkage of cement pastes made from CEM I 42.5R and CEM III/A 42.5N with a variable w/c ratio using the dilatometric method on a proprietary instrument covered by the patent PL241667. Furthermore, tests on consistency, setting times and compressive strength were performed after 2, 7 and 28 days of curing. From the analyses carried out, it was found that cement pastes containing blast furnace cement show greater autogenous shrinkage over a period of 28 days compared to pastes containing Portland cement. The pozzolanic reaction of granulated blast furnace slag contributes to the increase in recorded autogenous shrinkage. An increase in the water-cement ratio has an impact on the decreased strength gain, and the value of autogenous shrinkage. The research results indicate the need to take autogenous shrinkage into account when designing high-performance concretes containing blast furnace cement due to the increased susceptibility to shrinkage microcracks and for the durability of the material.

REGULATIONS OF THE FORMATION OF BAINETIC COMPONENT MATRIX IN ECONOMY ALLOYED CHROMO-MANGANESE ALLOYS

Purpose. The purpose of the investigation is to establish the regularities of the kinetics of supercooled austenite decomposition in the bainite temperature range (400−200 °C) in chromium-manganese cast iron for the development of thermal hardening regimes that increase the service life of products. Methodology. The object of the study are samples of research and industrial smelting of chrome-manganese cast iron containing 3,1 % carbon, 13,1 % chromium, and 15,75 % manganese. The study of the supercooled austenite decomposition kinetics was carried out by the dilatometric method in the temperature range of 400−200 °C, the study of the microstructure, phase composition, as well as the measurement of microhardness and hardness was carried out according to standard methods. Scientific novelty. The peculiarities of the supercooled austenite decomposition kinetics in the bainite temperature range (400−200 °С) in chromium-manganese cast iron were determined, the structure of the cast iron after aging consists of eutectic carbides Me (Cr, Mn, Fe)7C3, products of austenite decomposition, secondary carbides Me (Cr, Mn, Fe)7C3, Me (Cr, Mn, Fe)3C, as well as untransformed austenite in the amount of 70...75 %. The maximum hardness of the experimental cast iron was established during isothermal exposure at 350 °C for 35 hours. Practical value. The established regularities of the chromium-manganese cast iron structure formation and the determined and optimized temperature-time intervals of the supercooled austenite isothermal decomposition in cast iron are the basis for the development of heat treatment regimes to increase the strength, wear resistance of the material and the service life of its products.

The Effect of Radial-Shear Rolling Deformation Processing on the Structure and Properties of Zr-2.5Nb Alloy.

The rheological properties of the Zr-2.5Nb alloy by the strain rate range of 0.5-15 s-1 and by the temperature range of 20-770 °C was studied. The dilatometric method for phase states temperature ranges was experimentally determined. A material properties database for computer FEM simulation regards the indicated temperature-velocity ranges were created. Using this database and DEFORM-3D FEM-softpack, the radial shear rolling complex process numerical simulation was carried out. The contributed conditions for the ultrafine-grained state alloy structure refinement were determined. Based on the simulation results, a full-scale experiment of Zr-2.5Nb rod rolling a on a radial-shear rolling mill RSP-14/40 was carried out. It takes in seven passes from a diameter of 37-20 mm with a total diameter reduction ε = 85%. According to this case simulation data, the total equivalent strain in the most processed peripheral zone 27.5 mm/mm was reached. Due to the complex vortex metal flow, the equivalent strain over the section distribution was uneven with a gradient reducing towards the axial zone. This fact should have a deep effect on the structure change. Changes and structure gradient by sample section EBSD mapping with 2 mm resolution were studied. The microhardness section gradient by the HV 0.5 method was also studied. The axial and central zones of the sample by the TEM method were studied. The rod section structure has an expressed gradient from the formed equiaxed ultrafine-grained (UFG) structure on a few outer millimeters of the peripheral section to the elongated rolling texture in the center of the bar. The work shows the possibility of processing with the gradient structure obtaining and enhanced properties for the Zr-2.5Nb alloy, and a database for this alloy FEM numerical simulations are also presents.

STUDY OF RADICAL COPOLYMERIZATION REACTION OF UNSATURATED POLYESTERS WITH ACRYLIC ACID

One of the promising and inexpensive types of raw materials, taking into account the use of modern technologies for the production of sealing and adhesive materials, are unsaturated polyesters of various compositions.The aimof this work is to study the reaction of radical copolymerization of polyethylene(propylene)-glycolfumarate with acrylic acid in a dioxane solution at various molar ratios of the initial polymer-monomer mixture. Methodology.The composition of the copolymers was identifiedby HPLC spectroscopy by analyzing the mother liquors, the structure was confirmed by IR spectroscopy. The copolymerization kinetics was studied by the dilatometric method. The degree of swelling of the copolymers was determined by the gravimetric method, and their degree of unsaturation, by the bromid-bromate method. Radical copolymerization constants calculated by the Mayo-Lewis integral method.The results obtainedindicate thatfor any composition of the initial polymer-monomer mixture, the composition of the copolymer is enriched with acrylic acid links, and with an increase in its content in the initial polymer-monomer mixture, the reaction rate increases significantly.An increase in the content of unsaturated polyester in the initial polymer-monomer mixture leads to a decrease in the ability of the copolymer to absorb moisture, which makes it possible to assume their use as bases in the production of sealing and adhesive materials. Conclusion. An analysis of the numerical values of the copolymerization constants showed a higher activity of acrylic acid in comparison with unsaturated polyesters, thereby confirming the previously put forward assumption aboutthe relatively lower reactive ability of the latter.

Thermal Analysis of Ni-Cu Alloy Nanocomposites Processed by Sand Mold Casting

Ni-Cu based alloy metal matrix nanocomposites are in great demand for advanced technological applications due to their high temperature, strength, and better thermal properties. The aim is to investigate the thermal conductivity and coefficient of thermal expansion of the nickel based alloy nanocomposites reinforced with titanium dioxide (TiO2) which varies from 3 to 12 weight % nanoparticulates (45 to 60 nm). The thermal conductivity was measured using a comparative cut bar method (ASTM E1225), and thermal expansion was analyzed using a push-rod dilatometer method (ASTM E228). From experimentation, it was observed that thermal conductivity of the nanocomposites activity increases with inclusion of the nanoparticles up to 9 weight % after descent due to the temperature effects in nanocomposites, and thermal expansion of the nanocomposites decreases with addition of the nanoparticles up to 9 weight % and further rises marginally due to ductility of composites. Due to the incorporation of hard ceramic particles into the matrix, the composites’ thermal conductivity increases to 57.42 W/m℃, and their thermal expansion decreases to 12 × 10−6. Nickel alloys are widely used in marine, automotive, valve, pump, and aircraft applications.

Effect of Substituents on the Homopolymerization Activity of Methyl Alkyl Diallyl Ammonium Chloride.

Among nitrogen-containing cationic electrolytes, diallyl quaternary ammonium salt is a typical monomer with the highest positive charge density, which has attracted the most attention, especially in the research on homopolymers and copolymers of dimethyl diallyl ammonium chloride (DMDAAC), which occupy a very unique and important position. In order to improve the lipophilicity of substituted diallyl ammonium chloride monomers under the premise of high cationic charge density, the simplest, most direct, and most efficient structure design strategy was selected in this paper. Only one of the substituents on DMDAAC quaternary ammonium nitrogen was modified by alkyl; the substituents were propyl and amyl groups, and their corresponding monomers were methyl propyl diallyl ammonium chloride (MPDAAC) and methyl amyl diallyl ammonium chloride (MADAAC), respectively. The effect of substituent structure on the homopolymerization activity of methyl alkyl diallyl ammonium chloride was illustrated by quantum chemical calculation and homopolymerization rate determination experiments via ammonium persulfate (APS) as the initiator system. The results of quantum chemistry simulation showed that, with the finite increase in substituted alkyl chain length, the numerical values of the bond length and the charge distribution of methyl alkyl diallyl ammonium chloride monomer changed little, with the activation energy of the reactions in the following order: DMDAAC < MPDAAC < MADAAC. The polymerization activities measured by the dilatometer method were in the order DMDAAC > MPDAAC > MADAAC. The activation energies Ea of homopolymerization were 96.70 kJ/mol, 97.25 kJ/mol, and 100.23 kJ/mol, and the rate equation of homopolymerization of each monomer was obtained. After analyzing and comparing these results, it could be easily found that the electronic effect of substituent was not obvious, whereas the effect of the steric hindrance was dominant. The above studies have laid a good foundation for an understanding of the polymerization activity of methyl alkyl diallyl ammonium chloride monomers and the possibility of preparation and application of these polymers with high molecular weight.

Thermophysical properties of solid solutions of lead zirconate titanate obtained in various solid state states

Phase transitions in PbZrO3 (PZ), PbTiO3 (PT), and solid solutions of Pb(Zr1-xTix)O3 system were studied by dilatometric method. The temperature dependence of thermal expansion and linear coefficient of thermal expansion for both single crystals and ceramic samples exhibit several anomalies corresponding to phase transitions of different origin and correlate to the results of X-ray diffraction studies. The obtained results should be taken into account for development of materials and devices based on the studied solid solutions of Pb(Zr1-xTix)O3 system.

Validation of soil type interpretation and determination from CPT and DMT tests

This paper consists of three parts. The first part presents the methodology of in situ tests using a CPT probe and methods of soil type determination that are based on them. The second part lays out the methodology of field tests with Marchetti’s dilatometer (DMT) and methods of soil type determination on their basis. In the third part, the process of validation of CPT and DMT tests with borehole test methods is carried out based on the analysis of in situ investigations in the Warsaw University of Life Sciences (SGGW) Campus sites compared to the results obtained from laboratory tests. Validation of the CPT method using Marr’s nomogram was successful. The DMT method using Marchetti’s nomogram chart should be also considered as satisfactory.

Molar Volume and Surface Tension of Liquid Bi\u2013Cu Alloys

Bi–Cu alloys may potentially be used for thermal energy storage or as a catalyst for methane pyrolysis. For application research and simulations, it is necessary to know the reliable thermophysical properties of liquid alloys. Density of liquid Bi–Cu alloys (25, 50, 75 at. pct Cu) was measured with dilatometric method over the 971 K to 1500 K range. Density decreases linearly with temperature for all compositions. The molar volume calculated from measured densities shows positive excess molar volume. Surface tension was measured with maximum bubble pressure method over the 1125 K to 1500 K range. The data fitted with linear equations show that while the surface tension of 25 at. pct Cu decreases and that of 50 at. pct Cu alloy does not vary with temperature, the surface tension of 75 at. pct Cu alloy increases with temperature. The present results are confronted with literature data and several model calculations, part of which were performed in Pandat, and the reasons for positive excess molar volume and surface tension temperature coefficient are explained in terms of thermodynamics of Bi–Cu solutions.