The complexity and uncontrolled formation of struvite (MgNH₄PO₄·6H₂O) and its deposition in the technological equipment of wastewater treatment plants (WWTPs) are still the subject of research aimed at understanding the causes and proposing a remedial action. In order to reduce the intensity of the precipitation of struvite in wastewater treatment plants, it is recommended, among others, to limit flow velocity to below 1.5 m·s^-1. Literature analysis showed that there are no studies on the precipitation of struvite deposits in pipelines. Most studies focus on the deliberate precipitation of struvite, for example phosphorus recovery, resulting in a molar ratio of 1:1:1 (NH₄⁺:PO₄^3-:Mg²⁺). In fact, in WWTPs, such concentrations do not occur, but there have been cases of the precipitation of this mineral (and its mixtures) in the sludge parts. In this paper, the study aimed at determining conditions for the precipitation of deposits with a significant participation of struvite on the inner walls of steel pipes. The study was conducted at a non-stoichiometric concentration of ingredients at different pH values, as well as under dynamic conditions with flow velocity below 1.5 m·s^-1. A mathematical formula (ANOVA) that can be used to determine the mass of deposits in relation to the concentration of ammonium, phosphate, pH and flow velocity was developed. Computational models were developed on to investigate struvite precipitation under different pH levels (8.0–9.5) and ionic concentrations. The studies were carried out on solutions containing ammonium (NH₄⁺), phosphate (PO₄^3-), and magnesium (Mg²⁺), at a flow velocities of 0.4, 0.9 and 1.4 m·s^-1. In order to determine the mathematical formula thanks to which the mass of precipitates can be determined, a special pilot study installation was constructed. The XPS surface analysis of sludge from sewage treatment plants showed a similar composition of compounds with sediments obtained in own research. The presence of struvite was suggested, but the share of atomic percentage of bonds to which struvite was classified is small and amounts to less than 4%. This means that sediments precipitated in the technological installations are a mixture of various compounds of which pure struvite may constitute only a small part.

The aim of presented studies was to develop a new geometry of the overflow part of standard ATD–C tester for derivative thermal analysis

in a way that it would allow to obtain samples for abrasion and mechanical properties tests in the same mould without the need of cutting

them from a block of material. The pattern of new ATD–P tester has parts reflecting implemented samples. Computer simulations

regarding initial verification of new tester were performed in NovaFlow software. Chromium cast iron melts were made for testing the

sampler in real conditions and TDA analysis for casting material were conducted. The sandmix was prepared on silica sand matrix per the

ALPHASET technology. This new solution greatly simplifies the preparations of materials difficult to machine.

The paper presents the results of studies of the effect of chromium concentration on the solidification process, microstructure and selected

properties of cast iron with vermicular graphite. The vermicular graphite cast iron was obtained by an Inmold process. Studies covered the

cast iron containing chromium in a concentration at which graphite is still able to preserve its vermicular form. The effect of chromium on

the temperature of eutectic crystallization and on the temperature of the start and end of austenite transformation was discussed. The conditions

under which, at a predetermined chromium concentration, the vermicular graphite cast iron of a pearlitic matrix is obtained were

presented, and the limit concentration of chromium was calculated starting from which partial solidification of the cast iron in a metastable

system takes place. The effect of chromium on the hardness of cast iron, microhardness of individual phases and surface fraction of carbides

was disclosed.

There exists a problem with an in situ diagnostics of contamination of ethyl alcohol in a human being exhaled air. When ethyl alcohol in a mouth blowing (in a gaseous state) exists, the characteristic C–H stretch absorption bands in –CH₃ and –CH₂ – functional groups in ethanol (CH₃–CH₂–OH) appear at a wavelength of λ = 3.42 μm. To investigate the presence of ethyl alcohol in exhaled human air, the light beam of λ = 3.42 μm is passing through an air sample. If one alternately measures the intensity of the investigated beam and the reference, a percentage of ethanol in the air sample can be estimated using a sensitive nondispersive infrared (NDIR) system with a stable operating flow mass detector. To eliminate a mechanical chopper and noise generating stepper motors, a photonic chopper as a liquid crystal shutter for λ = 3.42 μm has been designed. For this purpose, an innovative infrared nematic liquid crystal mixture was intentionally prepared. The working mixture was obtained by a selective removal of CH bonds and its exchange by heavier polar substituents, what ensures a lack of absorption band of C–H bonds. The paper presents theory, concept and final experimental results of the infrared nematic liquid crystals mixture and the liquid crystal shutter for breathalyzer applications.

Mechanical properties of aluminum-silicon alloys are defined by condition of alloying components in the structure, i.e. plastic metallic matrix created from solid solution  on the basis of Al, as well as hard and brittle precipitations of silicon. Size and distribution of silicon crystals are the main factors having effect on field of practical applications of such alloys. Registration of crystallization processes of the alloys on stage of their preparation is directly connected with practical implementation of crystallization theory to controlling technological processes, enabling obtainment of suitable structure of the material and determining its usage for specific requirements. An attempt to evaluate correlation between values of characteristic points laying on crystallization curves and recorded with use of developed by the author TVDA method (commonly denominated as ATND method) is presented in the paper together with assessment of hardness of tested alloy. Basing on characteristic points from the TVDA method, hardness of EN AC-AlSi9Mg alloy modified with strontium has been described in the paper in a significant way by the first order polynomial.

The paper presents results of examination of material parameters of cast iron with structure obtained under rapid resolidification conditions carried out by means of the nanoindentation method.

The aim of this work was to induce permanent birefringence both in typical liquid crystal cells and photonic crystal fibers (PCFs) by photo-polymerization. For this purpose three different liquid crystalline materials, namely E7, 5CB, and 6CHBT were combined with a mixture of RM257 monomer and a UV sensitive initiator with the percentage weight less than 10%. Due to the photo-polymerization process it was possible to achieve polymer-stabilized liquid crystal orientation inside LC cells and micro-sized cylindrical glass tubes. In particular, periodic change in spatial molecular orientation was achieved by selective photo-polymerization. Successful results obtained in these simple geometries allowed for the experimental procedure to be repeated in PCFs leading to locally-induced permanent birefringence in PCFs.

In this work studies on propagation properties of a microstructured polymer optical fibre infiltrated with a nematic liquid crystal are presented. Specifically, the influence of an infiltration method on the LC molecular alignment inside fibre air-channels and, thus, on light guidance is discussed. Switching between propagation mechanisms, namely the transition from modified total internal reflection (mTIR) to the photonic bandgap effect obtained by varying external temperature is also demonstrated.

These studies examined the concept of concentration and purification of several types of wastewater by freezing and thawing. The experiments demonstrated that freezing of contaminated liquid contributed to concentration of contaminants in solution as well as significant concentration and agglomeration of solid particles. A high degree of purification was achieved for many parameters. The results of comparative laboratory tests for single and multiple freezing are presented. It was found that there was a higher degree of concentration of pollutants in wastewater frozen as man-made snow than in bulk ice. Furthermore, the hypothesis that long storage time of liquid as snow and sufficient temperature gradient metamorphism allows for high efficiency of the concentration process was confirmed. It was reported that the first 30% of the melted liquid volume contained over 90% of all impurities. It gives great opportunities to use this method to concentrate pollutants. The results revealed that the application of this process in full scale is possible. Significant agglomeration of solid particles was also noted. Tests with clay slurry showed that repeated freezing and thawing processes significantly improve the characteristics of slurry for sedimentation and filtration.

In many systems of engineering interest the moment transformation of population balance is applied. One of the methods to solve the transformed population balance equations is the quadrature method of moments. It is based on the approximation of the density function in the source term by the Gaussian quadrature so that it preserves the moments of the original distribution. In this work we propose another method to be applied to the multivariate population problem in chemical engineering, namely a Gaussian cubature (GC) technique that applies linear programming for the approximation of the multivariate distribution. Examples of the application of the Gaussian cubature (GC) are presented for four processes typical for chemical engineering applications. The first and second ones are devoted to crystallization modeling with direction-dependent two-dimensional and three-dimensional growth rates, the third one represents drop dispersion accompanied by mass transfer in liquid-liquid dispersions and finally the fourth case regards the aggregation and sintering of particle populations.

Among the family of stainless steels, cast austenitic stainless steels (CASSs) are preferably used due to their high mechanical properties

and corrosion resistance. These steels owe their properties to their microstructural features consisting of an austenitic matrix and skeletal

or lathy type δ-ferrite depending on the cooling rate. In this study, the solidification behavior of CASSs (304L and 316L grades) was

studied using ThermoCalc software in order to determine the solidification sequence and final microstructure during cooling. Theoretical

findings were supported by the microstructural examinations. For the mechanical characterization, not only hardness measurements but

also tribological studies were carried out under dry sliding conditions and worn surfaces were examined by microscopy and 3D

profilometric analysis. Results were discussed according to the type and amount of microstructural features.

The article presents crystallization process of silicon molybdenum ductile cast iron (SiMo). The alloy with 5% silicon content and with

variable amounts of Mo in a range of 0-1% was chosen for the research. The carbon content in the analysed alloys did not exceed 3,1%.

The studies of crystallization process were based on thermal – derivative analysis (TDA). Chemical composition of all examined samples

was analysed with the use of LECO spectrometer. Additionally, the carbon and the sulphur content was determined basing on carbon and

sulphur LECO analyser. For metallographic examination, the scanning electron microscopy (SEM) with EDS analyser was used. Disclosed

phases have been also tested with the use of X-ray diffraction. The results allowed the description of crystallization processes of silicon

molybdenum ductile cast iron using thermal – derivative analysis (TDA). Conducted studies did not allow for the clear identification of all

complex phases containing molybdenum, occurring at the grain boundaries. Therefore, the further stages of the research could include the

use of a transmission electron microscope to specify the description of complex compounds present in the alloy.

This paper presents the effect of the temperature and hold time in the holding furnace of 226 silumin on the characteristic quantities of

TDA curves. The temperature of phase transformations and the cooling rate were tested.It has been shown that increasing both the hold

time and the temperature in the holdingfurnace cause the decreasethe end ofα+Al9Fe3Si2+β and α+Al2Cu+βternary eutectics

crystallizationtemperature in the tested silumin. This is due to the fact an increase in amounts of impurities as a result of reacting theliquid

alloy with the gases contained in the air.It has been shown, however, that examined technological factors ofthe metal preparation do not

cause systematic changes in the cooling rate.

The article is a case study of the steel milling ring casting of about 6 tonnes net weight. The casting has been cast in the steel foundry the authors have been cooperating with. The aim was to analyse the influence of the shape of the chills and the material which was used to make them on the casting crystallization process. To optimally design the chills the set of the computer simulation has been carried out with 3 chills’ shape versions and 3 material’s versions and the results have been compared with the technology being in use (no chills). The proposed chills were of different thermal conductivity from low to high. Their shapes were obviously dependant on the adjacent casting surface geometry but were the result of the attempt to optimise their effect with the minimum weight, too. The chills working efficiency was analysed jointly with the previously designed top feeders system. The following parameters have been chosen to compare their effectiveness and the crystallization process: time to complete solidification and so-called fed volume describing the casting feeding efficiency. The computer simulations have been carried out with use of MagmaSoft v. 5.2 software. Finally, the optimisation has led to 15% better steel yield thanks to 60% top feeders weight reduction and 40% shorter solidification time. The steel ring cast with use of such technology fulfil all quality criteria.

In the dissertation it has been shown, that so called “time-thermal treatment” (TTT) of the alloy in liquid state as overheating the metal

with around 250o

C above Tliq. and detailing it in temperature for 30 to 40 minutes has the influence on changing the crystallization

parameters (Tliq., TEmin.

, TEmax., TE(Me), TSol.). It was ascertained, that overheating the AlSi17Cu5Mg alloy substantially above Tliq. results

with microcrystalline structure. Evenly distributed in the eutectic warp primeval silicon crystals and supersaturated with alloying additives

of base content (Cu, Mg, Fe) of α(Al) solution, ensures not only increase durability in ambient temperature, but also at elevated

temperature (250o

C), what due to it’s use in car industry is an advantage.

Paper presents the results of studies on primary crystallization and wear resistance of high chromium cast iron inoculated with

ferrotitanium intended for work in abrasive conditions. Primary crystallization was examined with use of TDA method, wear tests of the

samples were conducted using the modified pin-on-disk method.

A numerical model of binary alloy crystallization, based on the cellular automaton technique, is presented. The model allows to follow the

crystallization front movement and to generate the images of evolution of the dendritic structures during the solidification of a binary

alloy. The mathematic description of the model takes into account the proceeding thermal, diffusive, and surface phenomena. There are

presented the results of numerical simulations concerning the multi-dendritic growth of solid phase along with the accompanying changes

in the alloying element concentration field during the solidification of Al + 5% wt. Mg alloy. The model structure of the solidified casting

was achieved and compared with the actual structure of a die casting. The dendrite interaction was studied with respect to its influence on

the generation and growth of the primary and secondary dendrite arms and on the evolution of solute segregation both in the liquid and in

the solid state during the crystallization of the examined alloy. The morphology of a single, free-growing dendritic crystal was also

modelled. The performed investigations and analyses allowed to state e.g. that the developed numerical model correctly describes the

actual evolution of the dendritic structure under the non-equilibrium conditions and provides for obtaining the qualitatively correct results

of simulation of the crystallization process.

The article shows results of studies of primary crystallization and wear resistance of Cr-Ni-Mo cast steel intended for work in corrosive

and abrasive conditions. The studies of primary crystallization were conducted with use of TDA method and modified tester allowing

measurement casting cooling time influence on the cooling and crystallization curves of studied alloys. After heat treatment of examined

cast steel wear tests of the samples were conducted on pin-on-disc type device.

By the method of modern physical material science (optic microscopy scanning and transmission electron microscopy) the analysis of structural phase states, the morphology of the second phase inclusions and defect substructure of Al-Si alloy (silumin) of hypoeutectic composition, subjected to electron beam processing was done with the following parameters: energy density 25-35 J/cm2, beam length 150 μs, pulse number – 3, pulse repetition rate – 0.3 Hz, pressure of residual gas (argon) 0.02 Pa. The surface irradiation results in the melting of the surface layer, the dissolution of boundary inclusions, the stricture formation of high speed cellular crystallization of submicron sizes, the repeated precipitation of the second phase nanodimentional particles. With the increased distance from the irradiation surface the layer containing the second phase inclusions of quasi-equilibrium shape along with the crystallization cells was revealed. It is indicative of the processes of Al-Si alloy structure globalization on electron beam processing.

To the main advantages of magnesium alloys belongs their low density, and just because of such property the alloys are used in aviation and rocket structures, and in all other applications, where mass of products have significant importance for conditions of their operation. To additional advantages of the magnesium alloys belongs good corrosion resistance, par with or even surpassing aluminum alloys. Magnesium is the lightest of all the engineering metals, having a density of 1.74 g/cm3 . It is 35% lighter than aluminum (2.7 g/cm3 ) and over four times lighter than steel (7.86 g/cm3 ). The Mg-Li alloys belong to a light-weight metallic structural materials having mass density of 1.35-1.65 g/cm3 , what means they are two times lighter than aluminum alloys. Such value of mass density means that density of these alloys is comparable with density of plastics used as structural materials, and therefore Mg–Li alloys belong to the lightest of all metal alloys. In the present paper are discussed melting and crystallization processes of ultra-light weight MgLi12,5 alloys recorded with use of ATND methods. Investigated magnesium alloy was produced in Krakow Foundry Research Institute on experimental stand to melting and casting of ultra-light weight alloys. Obtained test results in form of recorded curves from ATND methods have enabled determination of characteristic temperatures of phase transitions of the investigated alloy.

In this paper crystallization studies of low-alloyed construction cast steel were presented for different additions of chromium, nickel and

molybdenum modified with vanadium and titanium. Studies were conducted using developed TDA stand, which additionally enabled

evaluation of cooling rate influence on crystallization process of investigated alloys.

Today’s industry aims at such situation, where number of defective products, so called defects shall approach to zero. Therefore, one introduces a various changes in technology of production, introduces improvements which would help in accomplishment of this objective. Another important factor is introduction of different type of testing, which shall help in assessment which factor has significant effect on quantity of rejects, and which one could be neglected. Existence of casting rejects is unavoidable; therefore a new ideas, technologies and innovations are necessary in the entire widely understood foundry branch, in order to minimize such adverse effect. Performance of tests aimed at unequivocal determination of an effect of vibrations during crystallization on mechanical properties and porosity of the EN ACAlSi17 alloy was the objective of the present work. To do this, there were produced 36 castings from EN AC-AlSi17 alloy. All the castings underwent machining operations. Half of the casting was destined to strength tests, the other half served to determination of an effect of vibrations on porosity of the alloy. The specimens were divided into 12 groups, depending on amplitude of vibrations and tilt angle of metal mould during pouring operation.

This paper shows how it is possible to obtain an ausferrite in compacted graphite iron (CGI) without heat treatment of castings. Vermicular graphite in cast iron was obtained using Inmold technology. Molybdenum was used as alloying additive at a concentration from 1.6 to 1.7% and copper at a concentration from 1 to 3%. It was shown that ausferrite could be obtained in CGI through the addition of molybdenum and copper in castings with a wall thickness of 3, 6, 12 and 24 mm. Thereby the expensive heat treatment of castings was eliminated. The investigation focuses on the influence of copper on the crystallization temperature of the graphite eutectic mixture in cast iron with the compacted graphite. It has been shown that copper increases the eutectic crystallization temperature in CGI. It presents how this element influences ausferrite microhardness as well as the hardness of the tested iron alloy. It has been shown that above-mentioned properties increases with increasing the copper concentration.