Szymon Nosewicz, Ph.D., Eng.

Department of Information and Computational Science (ZIiNO)
Division of Computational Methods in Nonlinear Mechanics (PMOMN)
position: assistant professor
telephone: (+48) 22 826 12 81 ext.: 289
room: 413
e-mail: snosew

Doctoral thesis
2016-02-25Discrete element modeling of powder metallurgy processes 
supervisor -- Jerzy Rojek, Ph.D., Dr. Habil., Eng., IPPT PAN
666
 
Recent publications
1.Chmielewski M., Pietrzak K., Teodorczyk M., Nosewicz S., Jarząbek D., Zybała R., Bazarnik P., Lewandowska M., Strojny-Nędza A., Effect of metallic coating on the properties of copper-silicon carbide composites, APPLIED SURFACE SCIENCE, ISSN: 0169-4332, DOI: 10.1016/j.apsusc.2016.12.130, Vol.421, pp.159-169, 2017
Chmielewski M., Pietrzak K., Teodorczyk M., Nosewicz S., Jarząbek D., Zybała R., Bazarnik P., Lewandowska M., Strojny-Nędza A., Effect of metallic coating on the properties of copper-silicon carbide composites, APPLIED SURFACE SCIENCE, ISSN: 0169-4332, DOI: 10.1016/j.apsusc.2016.12.130, Vol.421, pp.159-169, 2017

Abstract:
In the presented paper a coating of SiC particles with a metallic layer were used to prepare copper matrix composite materials. The role of the layer was to protect the silicon carbide from decomposition and dissolution of silicon in the copper matrix during the sintering process. The SiC particles were covered by chromium, tungsten and titanium using Plasma Vapour Deposition method. After powder mixing of components, the final densification process via Spark Plasma Sintering (SPS) method at temperature 950C was provided. The almost fully dense materials were obtained (> 97.5%). The microstructure of obtained composites was studied using scanning electron microscopy as well as transmission electron microscopy. The microstructural analysis of composites confirmed that regardless of the type of deposited material, there is no evidence for decomposition process of silicon carbide in copper. In order to measure the strength of the interface between ceramic particles and the metal matrix, the micro tensile tests have been performed. Furthermore, thermal diffusivity was measured with the use of the laser pulse technique. In the context of performed studies, the tungsten coating seems to be the most promising solution for heat sink application. Compared to pure composites without metallic layer, Cu-SiC with W coating indicate the higher tensile strength and thermal diffusitivy, irrespective of an amount of SiC reinforcement. The improvement of the composite properties is related to advantageous condition of Cu-SiC interface characterized by well homogenity and low porosity, as well as individual properties of the tungsten coating material.

Keywords:
metal matrix composites, silicon carbide, metallic layers deposition, thermal conductovity, interface strength

2.Nosewicz S., Rojek J., Chmielewski M., Pietrzak K., Discrete element modeling and experimental investigation of hot pressing of intermetallic NiAl powder, ADVANCED POWDER TECHNOLOGY, ISSN: 0921-8831, DOI: 10.1016/j.apt.2017.04.012, Vol.28, pp.1745-1759, 2017
Nosewicz S., Rojek J., Chmielewski M., Pietrzak K., Discrete element modeling and experimental investigation of hot pressing of intermetallic NiAl powder, ADVANCED POWDER TECHNOLOGY, ISSN: 0921-8831, DOI: 10.1016/j.apt.2017.04.012, Vol.28, pp.1745-1759, 2017

Abstract:
This paper presents the numerical and experimental analysis of hot pressing of NiAl powder with an emphasis on the best possible representation of its main stages: initial powder compaction and pressure-assisted sintering. The numerical study has been performed within the discrete element framework. In the paper, an original viscoelastic model of hot pressing has been used. In order to ensure that the applied values of material parameters in numerical simulations are appropriate, the reference literature has been reviewed. It produced the relations and equations to estimate the values of all required sintering material parameters of the considered viscoelastic model. Numerical simulations have employed the geometrical model of the initial dense specimen generated by a special algorithm which uses the real grain distribution of powder. The numerical model has been calibrated and validated through simulations of the real process of hot pressing of intermetallic NiAl material. The kinetics of compaction, sintering and cooling stage indicated by the evolution of density, shrinkage and densification rate have been studied. The comparison of numerical and experimental results has shown a good performance of the developed numerical model.

Keywords:
Powder metallurgy; Hot pressing; Sintering; Simulation; Discrete element method; Nickel aluminide

3.Nosewicz S., Rojek J., Chmielewski M., Pietrzak K., Lumelskyj D., Application of the Hertz formulation in the discrete element model of pressure-assisted sintering, GRANULAR MATTER, ISSN: 1434-5021, DOI: 10.1007/s10035-016-0699-9, Vol.19, No.1, pp.16-1-8, 2017
Nosewicz S., Rojek J., Chmielewski M., Pietrzak K., Lumelskyj D., Application of the Hertz formulation in the discrete element model of pressure-assisted sintering, GRANULAR MATTER, ISSN: 1434-5021, DOI: 10.1007/s10035-016-0699-9, Vol.19, No.1, pp.16-1-8, 2017

Abstract:
This paper presents the numerical modelling of initial powder compaction and pressure-assisted sintering performed by original viscoelastic discrete element model. The research is focused on the influence of the type of the model representing an elastic part of interparticle force. Two elastic contact models—linear and nonlinear Hertz model—have been implemented and used to analyse interaction of NiAl powder particles during compaction and sintering process. Numerical models have been validated using own experimental results. Microscopic effects (particle penetration) and macroscopic changes (relative density) have been compared. It has been shown that although both models represent properly macroscopic behaviour of the material at the sintering process, the Hertz model produces the results closer to the real experimental ones during the initial compaction stage. Evaluation of macroscopic quantities enables implementation of the discrete element model in the framework of the multiscale modelling framework which is currently developed for sintering processes.

Keywords:
Powder metallurgy, Sintering, Initial compaction, Elasticity, Discrete element method

4.Chmielewski M., Pietrzak K., Strojny-Nędza A., Jarząbek D., Nosewicz S., Investigations of interface properties in copper-silicon carbide composites, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.1515/amm-2017-0200, Vol.62, No.2B, pp.1315-1318, 2017
Chmielewski M., Pietrzak K., Strojny-Nędza A., Jarząbek D., Nosewicz S., Investigations of interface properties in copper-silicon carbide composites, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.1515/amm-2017-0200, Vol.62, No.2B, pp.1315-1318, 2017

Abstract:
This paper analyses the technological aspects of the interface formation in the copper-silicon carbide composite and its effect on the material’s microstructure and properties. Cu-SiC composites with two different volume content of ceramic reinforcement were fabricated by hot pressing (HP) and spark plasma sintering (SPS) technique. In order to protect SiC surface from its decomposition, the powder was coated with a thin tungsten layer using plasma vapour deposition (PVD) method. Microstructural analyses provided by scanning electron microscopy revealed the significant differences at metal-ceramic interface. Adhesion force and fracture strength of the interface between SiC particles and copper matrix were measured. Thermal conductivity of composites was determined using laser flash method. The obtained results are discussed with reference to changes in the area of metal-ceramic boundary.

Keywords:
copper matrix composites, silicon carbide, interface, thermal conductivity, adhesion

5.Chmielewski M., Pietrzak K., Strojny-Nędza A., Kaszyca K., Zybala R., Bazarnik P., Lewandowska M., Nosewicz S., Microstructure and thermal properties of Cu-SiC composite materials depending on the sintering technique, SCIENCE OF SINTERING, ISSN: 0350-820X, DOI: 10.2298/SOS1701011C, Vol.49, pp.11-22, 2017
Chmielewski M., Pietrzak K., Strojny-Nędza A., Kaszyca K., Zybala R., Bazarnik P., Lewandowska M., Nosewicz S., Microstructure and thermal properties of Cu-SiC composite materials depending on the sintering technique, SCIENCE OF SINTERING, ISSN: 0350-820X, DOI: 10.2298/SOS1701011C, Vol.49, pp.11-22, 2017

Abstract:
The presented paper investigates the relationship between the microstructure and thermal properties of copper–silicon carbide composites obtained through hot pressing (HP) and spark plasma sintering (SPS) techniques. The microstructural analysis showed a better densification in the case of composites sintered in the SPS process. TEM investigations revealed the presence of silicon in the area of metallic matrix in the region close to metal ceramic boundary. It is the product of silicon dissolving process in copper occurring at an
elevated temperature. The Cu-SiC interface is significantly defected in composites obtained through the hot pressing method, which has a major influence on the thermal conductivity of materials.

Keywords:
Metal matrix composites; Silicon carbide; Interface; Spark plasma sintering; Thermal conductivity.

6.Chmielewski M., Nosewicz S., Kurpaska Ł., Romelczyk B., Evolution of material properties during the sintering process of Cr-Re-Al2O3 composites, COMPOSITES PART B-ENGINEERING, ISSN: 1359-8368, DOI: 10.1016/j.compositesb.2016.04.065, Vol.98, pp.88-96, 2016
Chmielewski M., Nosewicz S., Kurpaska Ł., Romelczyk B., Evolution of material properties during the sintering process of Cr-Re-Al2O3 composites, COMPOSITES PART B-ENGINEERING, ISSN: 1359-8368, DOI: 10.1016/j.compositesb.2016.04.065, Vol.98, pp.88-96, 2016

Abstract:
This paper constitutes an analysis of the effect of heat treatment time on the properties of Cr-Re-Al2O3 composite materials. It was found that as a result of sintering, rhenium is dissolved in chromium to create chromium-rhenium solid solution. This process is time-dependent, therefore as the time extends, the structure of material becomes homogenous, which improves its mechanical properties. Within the frame of herein presented studies, a series of technological tests have been carried out for a constant sintering temperature (1450°C) and pressure (30 MPa), with the use of a variable holding time in the maximum temperature. As a result, changes in the structure of Crsingle bondRe matrix have been determined and the resulting changes in the properties of composite. Based on those tests, optimal conditions of the sintering process have been determined from the point of view of obtaining a homogenous structure and the most beneficial properties of Cr-Re-Al2O3 composites.

Keywords:
Metal-matrix composites (MMCs), Mechanical properties, Mechanical testing, Sintering

7.Chmielewski M., Nosewicz S., Jakubowska D., Lewandowska M., Mizera J., Rojek J., Bazarnik P., The influence of sintering time on the microstructural properties of chromium-rhenium matrix composites, International Journal of Refractory Metals and Hard Materials, ISSN: 0263-4368, DOI: 10.1016/j.ijrmhm.2016.05.017, Vol.59, pp.78-86, 2016
Chmielewski M., Nosewicz S., Jakubowska D., Lewandowska M., Mizera J., Rojek J., Bazarnik P., The influence of sintering time on the microstructural properties of chromium-rhenium matrix composites, International Journal of Refractory Metals and Hard Materials, ISSN: 0263-4368, DOI: 10.1016/j.ijrmhm.2016.05.017, Vol.59, pp.78-86, 2016

Abstract:
This paper comprises the results of studies of the changes in the structure of Cr-Re-Al2O3 metal matrix depending on heat treatment time in sintering temperature. The density of material with the following composition: 95%(75%Cr-25%Al2O3)+5%Re was increased using the technique of sintering under pressure (30MPa) at the temperature of 1450°C. As a result, materials characterized by a high relative density (< 97% of theoretical density) were obtained. Next, they were subjected to structural tests including scanning and transmission electron microscopy as well as X-ray diffraction. Changes in the phase composition, grains size and parameters of crystallographic structure depending on heat treatment time were analysed. It was found that during sintering rhenium is dissolved in the chromium matrix and Cr-Re solid solution is formed. When sintering time is extended to 120 min, the matrix of the composite becomes completely homogenous, which results in an increased strength of the composite.

Keywords:
Metal matrix composites, Rhenium, Hot pressing, Microstructure analysis, XRD

8.Jurczak K., Rojek J., Nosewicz S., Lumelskyy D., Bochenek K., Chmielewski M., Pietrzak K., Modelowanie wstępnego prasowania proszków metodą elementów dyskretnych, HUTNIK - WIADOMOŚCI HUTNICZE, ISSN: 1230-3534, DOI: 10.15199/24.2016.1.1, Vol.83, No.1, pp.3-7, 2016
Jurczak K., Rojek J., Nosewicz S., Lumelskyy D., Bochenek K., Chmielewski M., Pietrzak K., Modelowanie wstępnego prasowania proszków metodą elementów dyskretnych, HUTNIK - WIADOMOŚCI HUTNICZE, ISSN: 1230-3534, DOI: 10.15199/24.2016.1.1, Vol.83, No.1, pp.3-7, 2016

Abstract:
W niniejszym artykule zaprezentowano wyniki modelowania zagęszczania proszku stanowiącego wstępny etap procesu prasowania na gorąco. Modelowanie numeryczne zrealizowano metodą elementów dyskretnych z wykorzystaniem kulistych cząstek. Analizę skoncentrowano na badaniu mechanizmów zagęszczania proszku przy ciśnieniu do 50 MPa oraz poszukiwaniu modeli odpowiednich przy zastosowanych warunkach realizacji procesu. Symulacje numeryczne wykonano wykorzystując dwa modele oddziaływania cząstek proszku: sprężysty model Hertza-Mindlina-Deresiewicza oraz plastyczny model Storåkersa. Wyniki numeryczne zostały porównane z wynikami laboratoryjnymi prasowania proszku NiAl. Otrzymano dużą zgodność wyników eksperymentalnych i numerycznych.

This paper presents the results of discrete element simulation of powder compaction which is the initial stage in the hot pressing process. Numerical simulation has been performed by discrete element method with using spherical particles. The research has been focused on densification mechanisms under pressure 50 MPa and models appropriate for these conditions. Numerical simulations have been carried out for two contact models: elastic Hertz-Mindlin-Deresiewicz and plastic - Storåkers. Numerical results and results from laboratory test of the uniaxial pressing of NiAl powder have been compared. The obtained results of numerical simulation and laboratory tests showing a good agreement.

Keywords:
metoda elementów dyskretnych, prasowanie proszków, materiały intermetaliczne, discrete element method, powder compaction, intermetallics

9.Rojek J., Nosewicz S., Jurczak K., Chmielewski M., Bochenek K., Pietrzak K., Discrete element simulation of powder compaction in cold uniaxial pressing with low pressure, Computational Particle Mechanics, ISSN: 2196-4378, DOI: 10.1007/s40571-015-0093-0, Vol.3, pp.513-524, 2016
Rojek J., Nosewicz S., Jurczak K., Chmielewski M., Bochenek K., Pietrzak K., Discrete element simulation of powder compaction in cold uniaxial pressing with low pressure, Computational Particle Mechanics, ISSN: 2196-4378, DOI: 10.1007/s40571-015-0093-0, Vol.3, pp.513-524, 2016

Abstract:
This paper presents numerical studies of powder compaction in cold uniaxial pressing. The powder compaction in this work is considered as an initial stage of a hot pressing process so it is realized with relatively low pressure (up to 50 MPa). Hence the attention has been focused on the densification mechanisms at this range of pressure and models suitable for these conditions. The discrete element method employing spherical particles has been used in the numerical studies. Numerical simulations have been performed for two different contact models—the elastic Hertz–Mindlin–Deresiewicz model and the plastic Storåkers model. Numerical results have been compared with the results of laboratory tests of the die compaction of the NiAl powder. Comparisons have shown that the discrete element method is capable to represent properly the densification mechanisms by the particle rearrangement and particle deformation.

Keywords:
Discrete element method, Simulation, Powder compaction, Cold uniaxial pressing

10.Chmielewski M., Nosewicz S., Rojek J., Pietrzak K., Mackiewicz S., Romelczyk B., A study of densification and microstructure evolution during hot pressing of NiAl/Al2O3 composite, Advanced Composite Materials, ISSN: 0924-3046, DOI: 10.1080/09243046.2013.879408, Vol.24, No.1, pp.57-66, 2015
Chmielewski M., Nosewicz S., Rojek J., Pietrzak K., Mackiewicz S., Romelczyk B., A study of densification and microstructure evolution during hot pressing of NiAl/Al2O3 composite, Advanced Composite Materials, ISSN: 0924-3046, DOI: 10.1080/09243046.2013.879408, Vol.24, No.1, pp.57-66, 2015

Abstract:
Evolution of the density and the microstructure during hot pressing of NiAl/Al2O3 composite has been investigated in the present paper. In particular, the effect of the process parameters, viz. compacting pressure, sintering temperature and sintering time, on the evolution of the density of the intermetallic–ceramic composite has been studied. Evolution of the density has been related to microstructure changing. Porosity, pore structures and grains rearrangement have been analysed in microscopic observations.

Keywords:
hot pressing, sintering, intermetallic–ceramic composite, density evolution, microstructure

11.Rojek J., Nosewicz S., Pietrzak K., Chmielewski M., Evaluation of macroscopic stresses in discrete element models of sintering processes, COMPUTER METHODS IN MATERIALS SCIENCE / INFORMATYKA W TECHNOLOGII MATERIAŁÓW, ISSN: 1641-8581, Vol.15, No.1, pp.219-255, 2015
Rojek J., Nosewicz S., Pietrzak K., Chmielewski M., Evaluation of macroscopic stresses in discrete element models of sintering processes, COMPUTER METHODS IN MATERIALS SCIENCE / INFORMATYKA W TECHNOLOGII MATERIAŁÓW, ISSN: 1641-8581, Vol.15, No.1, pp.219-255, 2015

Abstract:
This paper presents investigation of macroscopic stresses in powder metallurgy process modelled with the discrete element method. The discrete element model belongs to the class of micromechanical models. In the DEM model the material is represented by an assembly of particles interacting by contact forces and the method is formulated in terms of forces and displacements. In order to evaluate macroscopic stresses a special upscaling procedure is necessary. The paper presents basic formulation of the discrete element method with special attention for the contact interaction models for powder compaction and sintering. A method to evaluate macroscopic stresses based on the two level averaging is presented. The discrete element model of sintering is verified using own experimental results. Macroscopic stresses are calculated for the whole process including loading, heating, sintering, cooling and unloading. It has been found out that the macroscopic stresses are consistent with changing process parameters. The procedure is suitable for multiscale modelling of sintering.

Keywords:
sintering, modeling, discrete element method, macroscopic stresses

12.Nosewicz S., Rojek J., Mackiewicz S., Chmielewski M., Pietrzak K., Romelczyk B., The influence of hot pressing conditions on mechanical properties of nickel aluminide/alumina composite, Journal of Composite Materials, ISSN: 0021-9983, DOI: 10.1177/0021998313511652, Vol.48, No.29, pp.3577-3589, 2014
Nosewicz S., Rojek J., Mackiewicz S., Chmielewski M., Pietrzak K., Romelczyk B., The influence of hot pressing conditions on mechanical properties of nickel aluminide/alumina composite, Journal of Composite Materials, ISSN: 0021-9983, DOI: 10.1177/0021998313511652, Vol.48, No.29, pp.3577-3589, 2014

Abstract:
The influence of hot pressing conditions on mechanical properties of nickel aluminide/alumina composite has been investigated in the present paper. In particular, effect of the process parameters, viz. compacting pressure, sintering temperature and sintering time on the evolution of density, elastic constants and tensile strength properties of the intermetallic-ceramic composite has been studied. Elastic constants, the Young's modulus and Poisson's ratio, have been evaluated using an ultrasonic testing method, and the tensile strength has been determined by a Brazilian-type splitting test. Microscopic observations of microstructure evolution complemented the experimental procedure. Experimental results have been confronted with theoretical models showing a good agreement between the data compared.

Keywords:
Hot pressing, sintering, intermetallic-ceramic composite, elastic properties, Brazilian test, tensile strength, ultrasonic method

13.Chmielewski M., Nosewicz S., Pietrzak K., Rojek J., Strojny-Nędza A., Mackiewicz S., Dutkiewicz J., Sintering Behavior and Mechanical Properties of NiAl, Al2O3, and NiAl-Al2O3 Composites, Journal of Materials Engineering and Performance, ISSN: 1059-9495, DOI: 10.1007/s11665-014-1189-z, Vol.23, No.11, pp.3875-3886, 2014
Chmielewski M., Nosewicz S., Pietrzak K., Rojek J., Strojny-Nędza A., Mackiewicz S., Dutkiewicz J., Sintering Behavior and Mechanical Properties of NiAl, Al2O3, and NiAl-Al2O3 Composites, Journal of Materials Engineering and Performance, ISSN: 1059-9495, DOI: 10.1007/s11665-014-1189-z, Vol.23, No.11, pp.3875-3886, 2014

Abstract:
It is commonly known that the properties of sintered materials are strongly related to technological conditions of the densification process. This paper shows the sintering behavior of a NiAl-Al2O3 composite, and its individual components sintered separately. Each kind of material was processed via the powder metallurgy route (hot pressing). The progress of sintering at different stages of the process was tested. Changes in the microstructure were examined using scanning and transmission electron microscopy. Metal-ceramics interface was clean and no additional phases were detected. Correlation between the microstructure, density, and mechanical properties of the sintered materials was analyzed. The values of elastic constants of NiAl/Al2O3 were close to intermetallic ones due to the volume content of the NiAl phase particularly at low densities, where small alumina particles had no impact on the composite’s stiffness. The influence of the external pressure of 30 MPa seemed crucial for obtaining satisfactory stiffness for three kinds of the studied materials which were characterized by a high dense microstructure with a low number of isolated spherical pores.

Keywords:
ceramics, composites, electron, intermetallic, metallic matrix, microscopy, powder metallurgy, sintering, structural

14.Nosewicz S., Rojek J., Pietrzak K., Chmielewski M., Viscoelastic discrete element model of powder sintering, POWDER TECHNOLOGY, ISSN: 0032-5910, DOI: 10.1016/j.powtec.2013.05.020, Vol.246, pp.157-168, 2013
Nosewicz S., Rojek J., Pietrzak K., Chmielewski M., Viscoelastic discrete element model of powder sintering, POWDER TECHNOLOGY, ISSN: 0032-5910, DOI: 10.1016/j.powtec.2013.05.020, Vol.246, pp.157-168, 2013

Abstract:
This paper presents an original viscoelastic model of powder sintering developed within the discrete element framework. The viscous model used by other authors has been enriched by adding a spring connected in series to the viscous rheological element. In this way elastic and viscous effects in the particle interaction during sintering are treated using the Maxwell viscoelasticity. The new numerical model has been verified through simulation of simple problems of free sintering and sintering under pressure. Sintering processes have been treated as isothermic. In order to accelerate the analysis an algorithmic mass scaling has been used allowing to use larger time steps in the explicit time integration scheme. The results obtained using the new model are consistent with the standard viscous model. At the same time, a much better efficiency of the new model in comparison to the standard viscous one has been found because the critical time steps required by the viscoelastic model are much larger than those required by the viscous model. The new model has been applied to the simulation of real process of sintering of NiAl powder. The kinetics of sintering indicated by the evolution of density has been studied. The comparison of numerical and experimental results has shown a good performance of the developed numerical model.

Keywords:
Powder sintering, Simulation, Discrete element method, Viscoelastic model

15.Rojek J., Nosewicz S., Pietrzak K., Chmielewski M., Simulation of Powder Sintering Using a Discrete Element Model, ACTA MECHANICA ET AUTOMATICA, ISSN: 1898-4088, DOI: 10.2478/ama-2013-0030, Vol.7, pp.175-179, 2013
Rojek J., Nosewicz S., Pietrzak K., Chmielewski M., Simulation of Powder Sintering Using a Discrete Element Model, ACTA MECHANICA ET AUTOMATICA, ISSN: 1898-4088, DOI: 10.2478/ama-2013-0030, Vol.7, pp.175-179, 2013

Abstract:
This paper presents numerical simulation of powder sintering. The numerical model introduced in this work employs the discrete element method which assumes that material can be modelled by a large assembly of discrete elements (particles) of spherical shape interacting among one another. Modelling of sintering requires introduction of the cohesive interaction among particles representing interparticle sintering forces. Numerical studies of sintering have been combined with experimental studies which provided data for calibration and validation of the model. In the laboratory tests evolution of microstructure and density during sintering have been studied. Comparison of numerical and experimental results shows a good performance of the numerical model developed

Keywords:
Powder Sintering, Simulation, Discrete Element Method

16.Nosewicz S., Rojek J., Numeryczne modelowanie naprężeń rezydualnych w spiekanych materiałach kompozytowych, PRZEGLĄD MECHANICZNY, ISSN: 0033-2259, Vol.10, pp.30-34, 2013
Nosewicz S., Rojek J., Numeryczne modelowanie naprężeń rezydualnych w spiekanych materiałach kompozytowych, PRZEGLĄD MECHANICZNY, ISSN: 0033-2259, Vol.10, pp.30-34, 2013

Abstract:
Sintering process is one of the major method of manufacture technology of composite materials with intermetallic matrix reinforced by ceramic particles. In the final stage of sintering, during cooling of material, the microcracks may occur due to appearance of significant residual stress at the grain boundaries, which leads to progressive degradation of the material. This paper presents numerical modeling of micro- and macroscopic stress during and after sintering process composite materials. The original thermo-viscoelastic model of discrete elements have been performed. Numerical simulations have been carried out on the example of the NiAl-Al2O3 composite. The obtained results confirm correct and efficient performance of the proposed numerical model.

Keywords:
sintering, composite, residual stresses, discrete element method

17.Nosewicz S., Rojek J., Numeryczne modelowanie naprężeń występujących w trakcie oraz po procesie metalurgii proszków materiałów kompozytowych, PRACE NAUKOWE POLITECHNIKI WARSZAWSKIEJ, SERIA: MECHANIKA, ISSN: 0137-2335, Vol.253, pp.13-18, 2013
Nosewicz S., Rojek J., Numeryczne modelowanie naprężeń występujących w trakcie oraz po procesie metalurgii proszków materiałów kompozytowych, PRACE NAUKOWE POLITECHNIKI WARSZAWSKIEJ, SERIA: MECHANIKA, ISSN: 0137-2335, Vol.253, pp.13-18, 2013

Abstract:
W technologii metalurgii proszków spiekanie, wraz z chłodzeniem, jest jednym z kluczowych etapów wytwarzania materiałów kompozytowych na osnowie metalicznej, podczas którego może dochodzić do pękania materiału na skutek występujących na granicach faz naprężeń rezydualnych. Prezentowana praca przedstawia wyniki modelowania numerycznego naprężeń mikro- oraz makroskopowych występujących w trakcie oraz po procesie metalurgii proszków materiałów kompozytowych. Do analizy procesów metalurgii proszków został użyty oryginalny termo-lepkosprężysty model elementów dyskretnych. Symulacje numeryczne zostały przeprowadzone na przykładzie kompozytu NiAl-Al2O3. Uzyskane wyniki potwierdzają poprawne oraz efektywne działanie zaproponowanego modelu numerycznego.

Keywords:
metoda elementów dyskretnych, symulacje numeryczne, spiekanie, metalurgia proszków, naprężenia rezydualne

18.Nosewicz Sz., Rojek J., Pietrzak K., Chmielewski M., Kaliński D., Modelowanie procesu spiekania materiałów dwufazowych metodą elementów dyskretnych, RUDY I METALE NIEŻELAZNE, ISSN: 0035-9696, Vol.57, No.9, pp.599-603, 2012
Nosewicz Sz., Rojek J., Pietrzak K., Chmielewski M., Kaliński D., Modelowanie procesu spiekania materiałów dwufazowych metodą elementów dyskretnych, RUDY I METALE NIEŻELAZNE, ISSN: 0035-9696, Vol.57, No.9, pp.599-603, 2012

Abstract:
W niniejszym artykule zostały przedstawione nowe wyniki modelowania procesu spiekania metodą elementów dyskretnych. W sformułowaniu teoretycznym dla części sprężystej zastosowano model kontaktu Hertza w celu lepszego odwzorowania oddziaływania elementów kulistych w trakcie prasowania. Sformułowanie i implementację modelu rozszerzono na przypadek spiekania materiałów dwufazowych. Na podstawie badań literaturowych wyznaczono parametry materiałowe procesu, które zostały następnie zweryfikowane za pomocą wyników eksperymentalnych. Wyniki numeryczne ewolucji gęstości próbki porównano z wynikami doświadczalnymi otrzymując dużą zgodność.

Keywords:
materiały dwufazowe, metalurgia proszków, spiekanie, metoda elementów dyskretnych

19.Rojek J., Pietrzak K., Chmielewski M., Kaliński D., Nosewicz S., Discrete Element Simulation of Powder Sintering, COMPUTER METHODS IN MATERIALS SCIENCE / INFORMATYKA W TECHNOLOGII MATERIAŁÓW, ISSN: 1641-8581, Vol.11, No.1, pp.68-73, 2011
Rojek J., Pietrzak K., Chmielewski M., Kaliński D., Nosewicz S., Discrete Element Simulation of Powder Sintering, COMPUTER METHODS IN MATERIALS SCIENCE / INFORMATYKA W TECHNOLOGII MATERIAŁÓW, ISSN: 1641-8581, Vol.11, No.1, pp.68-73, 2011

Abstract:
This paper presents numerical modelling of powder sintering. The numerical model introduced in this work employs the discrete element method which assumes that material can be modelled by a large assembly of discrete elements (particles) of spherical shape interacting among one another. Modelling of sintering requires introduction of the cohesive interaction among particles representing inter-particle sintering forces. Numerical studies of sintering have been supplemented with experimental studies which provided data for calibration and validation of the model. In the laboratory tests evolution of microstructure and density during sintering have been studied. Comparison of numerical and experimental results shows a good performance of the numerical model developed.

Keywords:
powder sintering, powder metallurgy, simulation, discrete element method

20.Nosewicz S., Rojek J., Modelowanie spiekania proszków metodą elementów dyskretnych, PRACE NAUKOWE POLITECHNIKI WARSZAWSKIEJ, SERIA: MECHANIKA, ISSN: 0137-2335, Vol.238, pp.7-12, 2011

List of recent monographs
1.
512
Nosewicz S., Discrete element modeling of powder metallurgy processes, IPPT Reports on Fundamental Technological Research, 5, pp.1-183, 2016

Conference papers
1.Rojek J., Nosewicz S., Maździarz M., Kowalczyk P., Wawrzyk K., Lumelskyj D., Modeling of a Sintering Process at Various Scales, Procedia Engineering, ISSN: 1877-7058, DOI: 10.1016/j.proeng.2017.02.210, Vol.177, pp.263-270, 2017
Rojek J., Nosewicz S., Maździarz M., Kowalczyk P., Wawrzyk K., Lumelskyj D., Modeling of a Sintering Process at Various Scales, Procedia Engineering, ISSN: 1877-7058, DOI: 10.1016/j.proeng.2017.02.210, Vol.177, pp.263-270, 2017

Abstract:
This paper presents modeling of a sintering process at various scales. Sintering is a powder metallurgy process consisting in consolidation of powder materials at elevated temperature but below the melting point. Sintering models at the atomistic, microscopic and macroscopic scales have been presented. Sintering is a process governed by diffusion therefore the atomistic modeling using the molecular dynamics has been focused on investigation of the diffusion process. The micromechanical model has been developed within the framework of the discrete element method. It allows us to consider microstructure and its changes during sintering. The macroscopic model is based on the continuum phenomenological approach. It combines elastic, thermal and viscous creep deformation. The methodology to determine macroscopic quantities: stress, strains and constitutive viscous properties from the discrete element simulations has been presented. Possibilities of the developed models have been demonstrated by applying them to simulation of sintering of the intermetallic NiAl powder. Own experimental results have been used to calibrate and validate numerical models.

Keywords:
sintering, modeling, discrete element method, diffusion, molecular dynamics, macroscopic model


Conference abstracts
1.Rojek J., Nosewicz S., Development of a multiscale model of powder sintering, 5th KMM-VIN Industrial Workshop: Multi-scale and multi-physics materials modeling for advanced industries, 2016-01-26/01-27, Madryt (ES), pp.1, 2016
2.Rojek J., Jurczak K., Nosewicz S., Lumelskyj D., Chmielewski M., Contact models for discrete element simulation of the power compaction in a hot pressing process, CMIS 2016, Contact Mechanics International Symposium, 2016-05-11/05-16, Warszawa (PL), pp.28-29, 2016
3.Maździarz M., Rojek J., Nosewicz S., Molecular dynamics/statics simulation of Ni-Al nanoparticles sintering, ECCOMAS 2016, European Congress on Computational Methods in Applied Sciences and Engineering, 2016-06-05/06-10, Hersonissos (GR), pp.1, 2016
Maździarz M., Rojek J., Nosewicz S., Molecular dynamics/statics simulation of Ni-Al nanoparticles sintering, ECCOMAS 2016, European Congress on Computational Methods in Applied Sciences and Engineering, 2016-06-05/06-10, Hersonissos (GR), pp.1, 2016

Keywords:
Sintering, Powder Material, Ni-Al, Molecular Dynamics, Molecular Statics

4.Rojek J., Kowalczyk P., Nosewicz S., Jurczak K., Wawrzyk K., Micro-macro relationships from discrete element simulations of sintering, ECCOMAS 2016, European Congress on Computational Methods in Applied Sciences and Engineering, 2016-06-05/06-10, Hersonissos (GR), pp.1, 2016
Rojek J., Kowalczyk P., Nosewicz S., Jurczak K., Wawrzyk K., Micro-macro relationships from discrete element simulations of sintering, ECCOMAS 2016, European Congress on Computational Methods in Applied Sciences and Engineering, 2016-06-05/06-10, Hersonissos (GR), pp.1, 2016

Keywords:
sintering, discrete element method, multi-scale modeling

5.Nosewicz S., Jurczak K., Rojek J., Chmielewski M., Pietrzak K., Application of contact interaction of Hertz model to viscoelastic discrete element model of sintering, ISNNM, 14th International Symposium on Novel and Nano Materials, 2016-07-03/07-08, Budapeszt (HU), pp.119, 2016
6.Jurczak K., Rojek J., Nosewicz S., Lumelskyy D., Bochenek K., Chmielewski M., Pietrzak K., Modelowanie wstępnego prasowania proszków metodą elementów dyskretnych, KomPlasTech 2016, XXIII Konferencja Informatyka w Technologii Metali, 2016-01-17/01-20, Wisła (PL), pp.68, 2016
Jurczak K., Rojek J., Nosewicz S., Lumelskyy D., Bochenek K., Chmielewski M., Pietrzak K., Modelowanie wstępnego prasowania proszków metodą elementów dyskretnych, KomPlasTech 2016, XXIII Konferencja Informatyka w Technologii Metali, 2016-01-17/01-20, Wisła (PL), pp.68, 2016

Abstract:
W niniejszym artykule zaprezentowano wyniki modelowania, zagęszczania proszku stanowiącego wstępny etap procesu prasowania na gorąco, metodą elementów dyskretnych opisaną w [1]. Modelowanie numeryczne zrealizowano metodą elementów dyskretnych, z wykorzystaniem kulistych cząstek. Badania skoncentrowano na mechanizmach zagęszczania proszku przy ciśnieniu 50 MPa oraz modelach odpowiednich przy zastosowanych warunkach procesu. Numeryczne symulacje wykonano z wykorzystaniem dwóch modeli: pierwszy - elastyczny Hertz-Mindlin-Deresiewicz, drugi - plastyczny Storakers, opisanych w pracy [2]. Wyniki symulacji numerycznych zostały porównane z wynikami laboratoryjnymi zagęszczania proszku NiAl w matrycy. W rezultacie otrzymano dużą zgodność wyników eksperymentalnych i numerycznych.

Keywords:
metoda elementów dyskretnych, modelowanie, zagęszczanie proszków, prasowanie

7.Rojek J., Nosewicz S., Maździarz M., Kowalczyk P., Wawrzyk K., Modelling of powder sintering at various scales, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P193, pp.1-2, 2016
Rojek J., Nosewicz S., Maździarz M., Kowalczyk P., Wawrzyk K., Modelling of powder sintering at various scales, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P193, pp.1-2, 2016

Keywords:
sintering, multiscale modelling

8.Nosewicz S., Rojek J., Pietrzak K., Chmielewski M., Discrete element modelling of hot pressing process, EUROMAT 2015, European Congress and Exhibition on Advanced Materials and Processes, 2015-09-20/09-24, Warszawa (PL), pp.1, 2015
9.Rojek J., Nosewicz S., Jurczak K., Viscoelastic cohesive contact formulation for discrete element model of powder sintering, ICCCM 2015, IV International Conference on Computational Contact Mechanics, 2015-05-27/05-29, Hannover (DE), pp.1-2, 2015
Rojek J., Nosewicz S., Jurczak K., Viscoelastic cohesive contact formulation for discrete element model of powder sintering, ICCCM 2015, IV International Conference on Computational Contact Mechanics, 2015-05-27/05-29, Hannover (DE), pp.1-2, 2015

Keywords:
cohesive contact, discrete element method, viscoelasticity, sintering

10.Nosewicz S., Rojek J., Pietrzak K., Chmielewski M., Numerical modeling of stresses in composites manufactured by powder metallurgy, ICMM3, 3rd International Conference on Material Modelling incorporating 13th European Mechanics of Materials Conference, 2013-09-08/09-11, Warszawa (PL), pp.133, 2013
11.Rojek J., Nosewicz S., Pietrzak K., Chmielewski M., Discrete element modelling of powder metallurgy processes, Particles 2013, III International Conference on Particle-based Methods, 2013-09-18/09-20, Stuttgart (DE), pp.1, 2013
12.Rojek J., Nosewicz S., Pietrzak K., Chmielewski M., Simulation of powder sintering using a discrete element method, VII International Symposium on Mechanics of Materials and Structures, 2013-06-03/06-06, Augustów (PL), pp.59-60, 2013
13.Rojek J., Nosewicz Sz., Pietrzak K., Chmielewski M., Kaliński D., Discrete element simulation of powder metallurgy manufacturing process of metal-ceramic composites, ECCOMAX 2012, 6th European Congress on Computational Methods in Applied Sciences and Engineering, 2012-09-10/09-14, Wiedeń (AT), pp.1-2, 2012
14.Nosewicz Sz., Rojek J., Pietrzak K., Chmielewski M., Kaliński D., Kačianauskas R., Discrete Element Modelling of Solid State Sintering Process of Metal-Ceramic Composite, SolMech 2012, 38th Solid Mechanics Conference, 2012-08-27/08-31, Warszawa (PL), pp.172-173, 2012
15.Rojek J., Nosewicz S., Pietrzak K., Chmielewski M., Kaliński D., Modelling of powder sintering using the discrete element method, CMM 2011, 19th International Conference on Computer Methods in Mechanics, 2011-05-09/05-12, Warszawa (PL), pp.241-1-2, 2011