Wyniki wyszukiwania - Biblioteka Nauki

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Structural analysis of parts of personal computer hard disks

100%

Malcharcziková J. , Váňová P. , Jonšta P.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2008

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tom z. 92

51-52

EN

Personal computers including all its parts, CPU, monitor, keyboard and mouse belong to the group of "information technology and telecommunication equipment". At the present consumption rate personal computers are scrapped when they are fully or partly operating, but they do not satisfy their owners in their parameters. Operating parts, such as hard disks from personal computers, can be further used, e. g. as backup sources or by less demanding users. If it does not happen, electric and electronic waste is produced. According to the Waste Disposal Association it is necessary to support the use of waste in order to eliminate the amount of wastes determined for disposal and to preserve natural resources, particularly by reuse, recycling, composting and use of energy from wastes. Selected parts of waste hard disks from personal computers were evaluated metallographically. In addition, the used coatings were characterized and their thickness was determined. As it was found out, basic parts of hard disks are produced from basic metals, such as iron, aluminium and copper. The contents of the contribution should add to increasing knowledge and the possibilities of electrical waste recycling.

2

Options for material usage from discarded mobile telephones

100%

Váňová P. , Malcharcziková J. , Jonšta P.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2008

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tom z. 92

63-64

EN

Mobile telephones belong to the fastest updated electronic devices, which generates thousands of tons of waste every year. According to the research by the Nokia company, only very few mobile telephones are recycled after their expiration date, whereas 80 % of Nokia devices are recyclable and contain valuable sorts of material. It is exactly this type of electronic waste that can provide us with various usable material sorts including metals such as copper, iron, nickel, silver and gold. A mobile telephone contains approx. 15-18 % of copper and 3 - 8 % of iron. A significant part of a mobile telephone is composed from miscellaneous types of plastics which are easy to recycle after sorting. Out-of-use mobile telephones belong to the waste group of electrical and electronic devices. Therefore, with respect to the environment, it is necessary to pay an intensive attention to the issue of collecting and recycling this type of devices, since any mobile phone which is not used any more constitutes an environmental burden or the resource of valuable raw materials. This thesis includes a material analysis of selected mobile telephones.

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Structure characteristics of intermetallic NiAlZr based compound

100%

Malcharcziková J. , Kursa M. , Pohludka M.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2010

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tom z. 97

19-19

EN

Observations were made in orientated state of inter-metallic Ni3Al based compound alloyed by zirconium. Zirconium in the form of wire or plasma melted foundry alloy Ni-Zr were used for preparation of the samples. The samples were cast by induction vacuum casting into the shape of cylinders. These castings were then directionally solidified in corundum tubes with the specified apex angle in a two-zone crystallisation furnace. Used rate of directional solidification was 50 mm/h. Cross sections and longitudinal sections of individual samples were used for determination of porosity, micro-hardness and for evaluation of character of created structures. It was established that the basic matrix contained formations of Ni3Al and elongated formations of Ni5Al3. Inter-dendritic regions contain eutectics with lamellar structure, which is formed by the Ni3Al phase and by the Zr-rich phase. Microhardness in the samples was determined in detail on the surface of the scratch pattern in polished state in accordance with precisely defined procedure, both in longitudinal and cross section. The scratch patterns were afterwards slightly etched in order to determine microhardness in individual phases and on grain boundaries. Microhardness was measured on microhardness tester FM-100 with use of the measuring unit "automatic microhardness testing system FM-ARS". It is very interesting that no big differences were found between the values of microhardness in the basic phase of Ni3Al rich in zirconium and grain boundaries, where this value varied approx. within the interval from 360š40 HV 0.05. Only eutectics formed by the Ni3Al phase and by the Zr-rich phase showed an increased microhardness. Evaluation of structure has been further completed with determination of porosity. Porosity in these samples was not too high and its value is of the order of hundreths of percent.

4

Directional solidification - the method of structural modification of Ni3Al-B alloys

100%

Malcharcziková J. , Kursa M. , Pohludka M.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2010

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tom z. 97

20-20

EN

For purpose of investigation of high purity materials Ni-22Al-1B and Ni-24Al-1B alloys (all in at.%) were prepared by melting of basic components in vacuum induction furnace. The cylinder castings were afterwards directionally solidified in two-phase super-kanthal resistance furnace working on Bridgman's method principle. Re-melting proceeded in corundum tubes with the apex angle at 1 550°C and at uniform rate 50 mm/h. The alloys fabricated by this way were crossly and longitudinally cut and the sections were used for determination of porosity, micro-hardness and for evaluation of micro-structure. The common feature of micro-structure of the both alloys was its coarseness. Further features of structure were different. Long parallel lines of mesh passed through the sections with 22 at.% Al. It was not observed in the sections with 24 at.% Al. B-rich phase was inside of these structures. Definite composition of phase is still determinating for reason of boron low sensitivity of many detection devices. Micro-hardness determination of the samples of both alloys was measured on micro-hardness tester FM-100 with automatic testing unit FM-ARS 900. Two types of measurement were carried out. The first on unetched samples. This value characterized sample as component. The second it was measured micro-hardness of structures presented on scratch patterns after their etching. Average values of matrix micro-hardness were about 270š20 HV 0.05. The B-rich phase had much greater values. It is assumed, that phase can cohesively strengthen these alloys. The last measurement carried out on the samples of both alloys was determination of their porosity. Resultant values were approximally 0.05š0.03%.