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Hodnocení příčin havárie kompresoru pro čerpání zemního plynu

Pantělejev L., Pacal B., Vojtkuláková Z.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

2007

Vol. 321, z. 89

37-37

Analýza struktur patentovaných drátů

Vojtkuláková Z., Janová D., Pantělejev L.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

2007

Vol. 321, z. 89

49-49

Comparison of evaluation methods of the chemical inhomogeneity of ductile irons alloyed with graded nickel contents

Vojtkuláková Z., Pacal B.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

2004

z. 78

195-200

Graphite irons are multicomponental systems of Fe-C-Si-Mn-i, where i presents another possible additional element. Chemical inhomogeneity of their matrix strongly affects their mechanical and physical properties, and therefore their technical usage. Elemental redistribution during eutectic crystallization is determined, among others, by the distribution coefficients of an element M between the austenite and the melt saturated with carbon. To describe the elemental redistribution, effective distribution coefficient kef(M) is used. The kef(M) is defined as the ratio of concentration of the element M near the graphite to that measured at the periphery of the eutectic cell. Many distribution coefficient measurements in graphite irons show that elements increasing thermodynamic activity of carbon concentrate near graphite, hence their kef(M) after solidification is greater than 1. These are Si, Ni, Cu, Mg, P, S, Al and Co. On the contrary, elements like Mn, Cr, V and Mo, having kef(M) usually smaller than 1, concentrates at the eutectic cell boundary. The contribution deals with comparison of kef(M) for Si and Ni in the as cast state and after heat treatment. Two different methods were used for the effective distribution coefficient determination. Previous experiences show that reliably reproducible determination of kef(M) is possible only for the alloying element content in the order of units of weight percent. For the lower alloying elements content (in the order of 0.1 wt. %), the standard deviation grows due to the cast iron matrix inhomogeneity.

The metallographical evaluation of the surgical joint implants and their integration with the bone tissue

Vojtkuláková Z., Doležal P., Ptáček P.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

2002

z. 75

107-111

The paper is an example of an application of the possibilities of utilization of a well equipped metallographical laboratory for the medicine practics. It deals with the metallographic analysis and determination of the chemical composition of the hip joint cotyles material of the used as well as unused joint implants and also the analysis of surfaces of a used joint implant in order to verify its integration with bone.

Material engineers contribution to the topic "The most expensive need be the best"

Vojtkuláková Z., Pacal B.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

2000

Vol. 263, z. 63

199-202

Rastrovací tunelovací mikroskop - možnosti wyužití pro praxi

Vojtkuláková Z.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

1998

z. 57

147-151