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1

FGM based on copper–alumina composites for brake disc applications

Strojny‑Nędza Agata, Pietrzak Katarzyna, Gili Flavia, Chmielewski Marcin

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 3

279--291

EN

Copper–alumina composites of the interpenetrating networks type are interesting materials for many applications because of their properties. On the base of preliminary investigations and practical works, in order to obtain a material with high resistance to friction wear as well as good dissipation of heat generated during work, it was decided that a developed material would be prepared on the base of the Cu–Al2O3 composite, with a graded composition. In this paper, we present the developed method of manufacturing dense copper–alumina FGMs, using ceramic preform with a graded porosity infiltrated with molten copper. The article also presents the full characterization of the obtained materials and mainly the impact of microstructure on the useful properties. The produced gradient material of a Cu–Al2O3 brake disk underwent tribological tests under conditions resembling real conditions. These disks also went through a series of abrasive wear trials at different operation stages. In comparison with the reference material (i.e., grey cast iron), the obtained gradient materials are characterized by a lower degree of wear when retaining a similar coefficient of friction value due to the ceramic phase addition. Additionally, it was found that using the copper-based gradient material guarantees faster heat dissipation from the contact area.

2

Formowanie kompozytów gradientowych z układu ceramika-metal metodą odlewania odśrodkowego

Zygmuntowicz J., Miazga A., Konopka K., Kaszuwara W.

Szkło i Ceramika

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2016

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R. 67, nr 5

13--17

PL

Zapotrzebowanie na nowe materiały kompozytowe nieustanie się zwiększa. Rosną również oczekiwania odnośnie jakości nowych kompozytów oraz metod ich wytwarzania. Aktualnie kierunki rozwoju w zakresie wytwarzania materiałów kompozytowych koncentrują się na poprawie właściwości oraz opracowaniu nowych metod pozwalających wytwarzać kompozyty gradientowe. Głównym problemem stawianym przed inżynierami podczas projektowania kompozytów gradientowych jest kontrolowanie rozmieszczenia cząstek wzdłuż wybranego kierunku. Jedną z metod pozwalających uzyskać kompozyt gradientowy z układu ceramika-metal jest odlewanie odśrodkowe mas lejnych (ang. centrifugal slip casting). Metoda ta łączy w sobie klasyczne odlewanie z gęstwy z działaniem siły odśrodkowej. Pozwala na wytworzenie gotowego wyrobu w kształcie tulei. Wytworzone kompozyty charakteryzują się gradientową budową. Prace prowadzone były dla układu Al2O3-Ni. Na ich przekroju można dostrzec trzy strefy różniące się rozmieszczeniem cząstek niklu.

EN

Demands for new composite materials are continuously increasing, as well as quality requirements for the new composites and methods of their preparation. Currently, directions of development in the production of composite materials focus on improving the properties and inventing of new methods to produce graded composites. The main problem for the engineers designing functionally gradient composites, is to control distribution of the particles along the gradient direction. One of the method to obtain FGM ceramicmetal composite is the centrifugal slip casting. This method combines the classical slip casting with the centrifugal force. It allows the production of finished products in the shape of a hollow cylinder. This investigation was carried out for the Al2O3-Ni system. The resulting composites are characterized by microstructure with the gradient concentration of nickel particles, which has a three-zone microstructure.

3

The use of mathematical and computer modelling in solving the problems or rail transport expert examination

Kuzin N., Meshcheryakova T., Kuzin O., Kurileva E., Gordinskaya N.

Journal of Applied Mathematics and Computational Mechanics

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2016

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Vol. 15, nr 4

93--98

EN

The analysis of the current state of expert research of the failure of structural elements of railway rolling stock is presented. On the basis of the approaches of mechanics, mathematical and computer modeling the technique of establishing a mechanism for softening of parts and units of friction in the operation of rail transport is suggested.

4

FGMs generated method SHSM

Fraś E., Olejnik E., Janas A., Kolbus A.

Archives of Foundry Engineering

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2009

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Vol. 9, iss. 2

123-128

EN

In this study, a new SHSF (Self-Propagating High-Temperature Synthesis in Mould) process of synthesis of the functionally gradient materials (FGMs) was described. The said method enabled generating a thin, sub-surface layer of the MMC type in two alloys, i.e. in cast iron/NbC and Ni3Al/NbC systems. The layer was composed of fine-dispersed niobium carbides present in high volume content. The cast iron/NbC and Ni3Al/NbC materials fabricated by the SHSF process were next subjected to metallographic and structural examinations, combined with testing of mechanical properties.

5

Methods of preparing polymeric gradient composites

Stabik J., Dybowska A.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 25, nr 1

67-70

EN

Purpose: The goal of this work is to introduce basic methods of preparing polymeric gradient materials, which allow to join two different components to ensure the required properties and structure of the functionally gradient materials. Design/methodology/approach: In this paper few of methods of preparing functionally gradient polymeric materials are briefly described which were successful employed in many investigations performed during last few years. Findings: It was noticed that the knowledge about polymeric gradient materials is still developing what can allow to manufacture new products characterized by unique properties. Research limitations/implications: Most of methods presented in this paper are also used for conventional products, the difference between conventional products and products with gradient are quantity of components, shape and size of reinforcements, and properties of ready materials. Practical implications: Presented methods can be applied in preparing FGMs for future research programmes and also in industrial processes. Originality/value: Techniques are presented that can be useful in future scientific work concerning functionally gradient materials containing polymer materials.

6

Application of Trefftz method to steady-state heat conduction problem in functionally gradient materials

Kita E., Ikeda Y., Kamiya N.

Computer Assisted Mechanics and Engineering Sciences

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2003

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Vol. 10, No. 3

339-351

EN

This paper describes the application of Trefftz method to the steady-state heat conduction problem on the functionally gradient materials. Since the governing equation is expressed as the non-linear Poisson equation, it is difficult to apply the ordinary Trefftz method to this problem. For overcoming this difficulty, we will present the combination scheme of the Trefftz method with the computing point analysis method. The inhomogeneous term of the Poisson equation is approximated by the polynomial of the Cartesian coordinates to determine the particular solution related to the inhomogeneous term. The solution of the problem is approximated with the linear combination of the particular solution and the T-complete functions of the Laplace equation. The unknown parameters are determined so that the approximate solution will satisfy the boundary conditions by means of the collocation method. Finally, the scheme is applied to some numerical examples.

7

Materiały gradientowe jako nowe możliwości współczesnej techniki.

Hodor K., Zięba P., Olszowska-Sobieraj B.

Inżynieria Materiałowa

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1999

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R. XX, nr 6

595-600

PL

W pracy wyjaśniono istotę gradientu cechy materiałowej, dokonano przeglądu i klasyfikacji FGM w zależności od: rodzaju łączonych materiałów, zasięgu gradientu, geometrii gradacji, funkcji jaką pełni gradient i od tego, w jaki sposób gradient umożliwia osiągnięcie pożądanego efektu. Zaprezentowano procesy technologiczne, w wyniku których powstają FGM. Obok procesów konstruktywnych i metod opartych na zjawiskach transportu, zwrócono szczególną uwagę na metodę polegającą na połączeniu ze sobą metalu i związku międzymetalicznego przy wykorzystaniu przemiany eutektycznej. Podano przykłady zastosowań FGM w przemyśle lotniczym i kosmicznym, optyce, elektronice i medycynie. Omówiono krajowe zainteresowanie FGM, ze szczególnym uwzględnieniem możliwości otrzymania FGM bezpośrednio w wyniku procesu odlewniczego.

EN

In this paper current state of art in the area of FGM is presented. The principles of the material property gradient is explained, then FGM are classified into several groups according to the material classes they combine, the relative gradient extension, the geometry of the gradation, the function in a component and the way in which the gradient acts to achieve a desired response. Two basic processes of FGM productions are discussed, that is constructive one and transport one. Simultaneously, a new method of FGM manufacturing, like eutectic bounding is presented. Then, some examples of the applications of FGM in aeronautics and space industry, electronics, optics and medicine are given. National interest with FGM is briefly described including the most recent example of FGM production directly due casting process.

8

Functionally gradient materials in the SiC-Ti3SiC2 system.

Lis J., Łopaciński M., Rudnik T., Stobierski L.

Inżynieria Materiałowa

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1998

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R. XIX, nr 4

1280-1283

EN

Functionally Gradient Materials (FGMs) present a new form of composite laminates characterised by a continuous distribution of constituent phases without macroscopic phase boundaries. Such materials possess very promising charcteristics especially mechanical, thermal and chemical resistance. The authors present a preparation method of the new ceramic multilayered composites obtained according to the FGM concept with controlled hardness and fracture toughness. The two different ceramic materials, namely a very hard silicon carbide and a relatively soft ceramics of a high fracture toughness based on Ti3SiC2 were joined in one layered composite. The materials were prepared by a powder metallurgy procedure with the use of a hot-pressing technique. The starting sinterable powders were made separately by the Self-propagating High-temperature Synthesis. Then, after an appropriate preparation, they were hot-pressed in a graphite mould in an inert atmosphere. Microstructure investigations and indentation tests showed the FGM structure with a hardness distribution.