The Bulletin of the Polish Academy of Sciences: Technical Sciences (Bull.Pol. Ac.: Tech.) is published bimonthly by the Division IV Engineering Sciences of the Polish Academy of Sciences, since the beginning of the existence of the PAS in 1952. The journal is peer‐reviewed and is published both in printed and electronic form. It is established for the publication of original high quality papers from multidisciplinary Engineering sciences with the following topics preferred: Artificial and Computational Intelligence, Biomedical Engineering and Biotechnology, Civil Engineering, Control, Informatics and Robotics, Electronics, Telecommunication and Optoelectronics, Mechanical and Aeronautical Engineering, Thermodynamics, Material Science and Nanotechnology, Power Systems and Power Electronics.

Journal Metrics: JCR Impact Factor 2018: 1.361, 5 Year Impact Factor: 1.323, SCImago Journal Rank (SJR) 2017: 0.319, Source Normalized Impact per Paper (SNIP) 2017: 1.005, CiteScore 2017: 1.27, The Polish Ministry of Science and Higher Education 2017: 25 points.

Abbreviations/Acronym: Journal citation: Bull. Pol. Ac.: Tech., ISO: Bull. Pol. Acad. Sci.-Tech. Sci., JCR Abbrev: B POL ACAD SCI-TECH Acronym in the Editorial System: BPASTS.

The human desire to grasp the nature of fast phenomena has been driving technological progress for years, including in the field of ultrafast photography.

The chosen, typical causes of quality defects of cast-iron „alphin” rings embedded in aluminum cast are being presented in this paper.

Diffusive joint of those inserts with the pistons casts is being used, due to extreme work conditions of destructive influence of the fuel mix

and variable thermo-mechanical loads, which reign in the combustion motor working chamber.

The paper presents results of calorimetric studies of foundry nickel superalloys: IN100, IN713C, Mar - M247 and ŻS6 U. Particular attention was paid to determination of phase transiti ons temperatures during heating and cooling. The samples were heated to a temperature of 1500°C with a rate of 10°C ⋅ min – 1 and then held at this temperature for 5 min. After a complete melting, the samples were cooled with the same rat e. Argon with a purity of 99.99% constituted the protective atmosphere. The sample was placed in an alundum crucible with a capacity of 0.45 cm 3 . Temperature and heat calibration was carried out based on the mel ting point of high- purity Ni. The tests were carried out by the differential scanning calorimetry (DSC) using a Multi HTC high -temperature calorimeter from Setaram. Based on the DSC curves, the following temperatures were determined: solidus and liquidus, dissolution and precipitation of the γ ’ phase, MC carbides and melting of the γ ’ /γ eutectic. In the temperature range of 100 -1100°C, specific heat capacity of the investigated superalloys was determined. It was found that the IN713C and IN100 alloys exhibit a higher specific heat while compared to the Mar - M247 and ŻS6 U alloys.

Emergence of new designs for internal combustion engines resulted in a necessity to search for new materials which will rise to excessive technological requirements under operating conditions of modern internal combustion engines of up to 150 kW. Focusing only on material properties, theoretically existing alloys should meet presents requirements. More importantly, existing materials are well fitted to the entire crank-piston system. Thus, there is a need for a more thorough examination of these materials. The paper presents studies on determination of coefficient of friction μ and wear for the A390.0 alloy modified with AlTi5B master alloy combined with EN GJL-350 cast iron. The characteristics of a T-11 tribological tester (pin on disc) used for the tests, as well as the methodology of the tribological tests, were described. Also, the analysis of the surface distribution of elements for the pin and the disc was presented. The studies were realized in order to find whether the analyzed alloy meets the excessive requirements for the materials intended for pistons of modern internal combustion engines. The results show that the A390.0 alloy can only be applied to a load of 1.4 MPa. Above this value was observed destructive wear, which results in the inability to use it in modern internal combustion engines.

In the dissertation the data modeling has been shown for the data that regards the damages, which value is above zero. With the use of

Weibull distribution, with prior regression and correlation analysis chosen parameters that defines the life time and failure level of two

populations of AlSi17Cu5 were defined. The calculation sheet of reliability allows to create so called survival diagram, and on the basis of

durability data the average warrantee can be determined, on the pre-exploitation period.

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 the Tliq. and detaining it in this temperature for around 30 minutes, improves the mechanical properties (HB, Rm,

R0,2). It was ascertained, that overheating the AlSi17Cu5Mg alloy aids the modification, resulting with microcrystalline structure. Uniform

arrangement of the Si primeval crystals in the warp, and α(Al) solution type, supersaturated with alloying elements present in the base

content (Cu, Mg) assures not only increased durability in the ambient temperature, but also at elevated temperature (250o

C), what is an

advantage, especially due to the use in car industry.

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.

The paper presents the influence of modification with phosphorus (CuP10) on the tribological properties of the alloy AlSi17Cu5Mg coupled

abrasively with cast-iron EN GJL-350. Tests of coefficient of friction and wear of mass were conducted on tribological tester T-01. An

important aspect in the assessment of the tribological properties is the analysis of initial material microstructure in reference to silumin which

underwent modification with phosphorus. It was found that the difference in structure of tested materials, mainly sizes of primary silicon

crystals significantly influences the tribological properties whereas the speed change of the friction knot does not have such big influence.

The FMEA (Failure Mode and Effects Analysis) method consists in analysis of failure modes and evaluation of their effects based on

determination of cause-effect relationships for formation of possible product or process defects. Identified irregularities which occur

during the production process of piston castings for internal combustion engines were ordered according to their failure rates, and using

Pareto-Lorenz analysis, their per cent and cumulated shares were determined. The assessments of risk of defects occurrence and their

causes were carried out in ten-point scale of integers, while taking three following criteria into account: significance of effects of the defect

occurrence (LPZ), defect occurrence probability (LPW) and detectability of the defect found (LPO). A product of these quantities

constituted the risk score index connected with a failure occurrence (a so-called “priority number,” LPR). Based on the observations of the

piston casting process and on the knowledge of production supervisors, a set of corrective actions was developed and the FMEA was

carried out again. It was shown that the proposed improvements reduce the risk of occurrence of process failures significantly, translating

into a decrease in defects and irregularities during the production of piston castings for internal combustion engines.

The paper presents the results of studies on the effect of the AlSi17Cu5 alloy overheating to atemperature of 920°C and modification with phosphorus (CuP10) on the resultingmechanical (HB, Rm, R0.2) and plastic (A5 and Z) properties. It has been shown that, so-called, "timethermal treatment" (TTT) of an alloy in the liquid state, consisting inoverheating the metal to about 250°C above Tliq,holding at this temperature by 30 minutes improvesthe mechanical properties. It has also been found that overheating of alloy above Tliq.enhances the process of modification, resulting in the formation of fine-grain structure. The primary silicon crystals uniformly distributed in the eutectic and characteristics ofthe α(Al) solution supersaturated with alloying elements present in the starting alloy composition (Cu, Fe) provide not only an increase of strength at ambient temperature but also at elevated temperature (250°C).

In the paper the reasons for steam pipeline’s elbow material rupture, made of steel 13CrMo4-5 (15HM) that is being used in the energetics.

Based on the mechanical properties in the ambient temperature (Rm, Rp0,2 and elongation A5) and in the increased temperature (Rp0,2t

) it

was found, that the pipeline elbow’s material sampled from the ruptured area has lower Rp0,2 i Rp0,2t by around 2% than it is a requirement

for 13CrMo4-5 steel in it’s base state. The damage appeared as a result of complex stress state, that substantially exceeded the admissible

tensions, what was the consequence of considerable structure degradation level. As a result of the microstructure tests on HITACHI S4200

microscope, the considerable development of the creeping process associates were found. Also the advances progress of the microstructure

degradation was observed, which is substantial decomposition of bainite and multiple, with varied secretion size, and in most cases

forming the micro cracks chains. With the use of lateral micro sections the creeping voids were observed, that creates at some places the

shrinkage porosities clusters and micro pores.

In spite of the fact that in most applications, magnesium alloys are intended for operation in environments with room temperature, these

alloys are subject to elevated temperature and oxidizing atmosphere in various stages of preparation (casting, welding, thermal treatment).

At present, the studies focus on development of alloys with magnesium matrix, intended for plastic forming. The paper presents results of

studies on oxidation rate of WE43 and ZRE1 magnesium foundry alloys in dry and humidified atmosphere of N2+1%O2. Measurements of

the oxidation rate were carried out using a Setaram thermobalance in the temperature range of 350-480°C. Corrosion products were

analyzed by SEM-SEI, BSE and EDS. It was found that the oxide layer on the WE43 alloy has a very good resistance to oxidation. The

high protective properties of the layer should be attributed to the presence of yttrium in this alloy. On the other hand, a porous, two-layer

scale with a low adhesion to the substrate forms on the ZRE1 alloy. The increase in the sample mass in dry gas is lower than that in

humidified gas.

The authors present a proposal for modelling the process of scraping of load units (packages) from sorting belt conveyors with the use of deflection scrapers. The continuous scraping process was subjected to discretisation. Characteristic stages of the process were distinguished, such that determine different kinematics-dynamic properties of the load. The created model makes it possible to test the scraping process, and to optimise it.

The paper presents modelling proposal of the curvilinear scraper arm geometry by means of Bezier' s curve of the third degree. A physical model of scraping process of the unit load with the use of curvilinear arm for the most difficult sorting cases has been worked out. As a result of the performed numerical optimisation, there has been proposed the scraper arm shape geometry that makes it possible to decrease dynamic interaction exerted on the sorted loads.

The article presents a dynamic analysis of the sorting process of load units transported on conveyor belts. The process is realized by means of an active fence with one freedom degree. During analytic research the manipulated loads were treated as undeformable bodies, or in the case of load impact against the fence as the bodies with nonlinear springy-damping properties. A flexible element, described by Kelvin linear model, was used in the drive of the fence of a rotatably fixed beam. Appropriate choice of construction parameters makes it possible to mitigate the dynamic interactions of the sorted loads.

In accordance with the principles of conducting revitalization activities specified in the Revitalization Act in force from 9 October 2015 and horizontal guidelines for revitalization in operational programs for 2014-2020, the preparatory phase of the revitalization process should include multi-layered analyzes concluded with deductions included in communal urban regeneration programs. The article describes the role of student architectural and urban competitions performed in cooperation between municipalities and universities as innovative analytical and conceptual activities that could form the basis for specifying recommendations in revitalization strategies planned by a given municipality. The infl uence of the student competitions’ results on the development of the city revitalization strategy is presented on grounds of periodic competitions organized at the Faculty of Architecture of the Gdańsk University of Technology in cooperation with the Department of Plans and Marketing of the City Hall of the City of Gdańsk.

Paper present a thermal analysis of laser heating and remelting of EN AC-48000 (EN AC-AlSi12CuNiMg) cast alloy used mainly for

casting pistons of internal combustion engines. Laser optics were arranged such that the impingement spot size on the material was a

circular with beam radius rb changes from 7 to 1500 m. The laser surface remelting was performed under argon flow. The resulting

temperature distribution, cooling rate distribution, temperature gradients and the depth of remelting are related to the laser power density

and scanning velocity. The formation of microstructure during solidification after laser surface remelting of tested alloy was explained.

Laser treatment of alloy tests were perform by changing the three parameters: the power of the laser beam, radius and crystallization rate.

The laser surface remelting needs the selection such selection of the parameters, which leads to a significant disintegration of the structure.

This method is able to increase surface hardness, for example in layered castings used for pistons in automotive engines.