Wyniki wyszukiwania - BazTech

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Metallic alloy with shape memory – selected properties and engineering aspects

Kuś Krzysztof, Frączyk Adam, Wojtkowiak Adam

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2019

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nr 22(4)

337--350

EN

In the case of shape memory alloys (SMA), a form to which a material is expected to return during heating can be repeatedly programmed, whereas other related properties can be individually adjusted. It was found that most producers of commercial assortment based on SMA as well as traders are seldom willing to lift the veil of secrecy on this topic. In the context of own experimental studies, the authors made a reference to the technical aspects of some post-treatments of a Ni-Ti alloy with a view to further practical application, e.g. the design and construction of machinery and structures with the involvement of SMA. For these purposes, high-temperature shape setting trials were carried out using various parameters of heat treatment with no secrecy surrounding the procedures applied. Some of the tested parameters proved effective, whereas some were less useful. Following the activation of the reverse transformation by heating, a somewhat different behaviour was observed, and simultaneously one of the crucial material temperatures was determined. The paper as a whole is reported from a specifically engineering/technical point of view, which is continuously emphasized in the content of the presented article.

2

Influence of gas detonation spraying parameters on the geometrical structure of Fe-Al intermetallic protective coatings

Chrostek Tomasz, Bramowicz Mirosław, Rychlik Kazimierz, Wojtkowiak Adam, Senderowski Cezary

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2019

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nr 22(3)

249--262

EN

The paper presents the results of an analysis of the geometrical structure of Fe-Al intermetallic protective coatings sprayed under specified gun detonation spraying (GDS) conditions. Two barrel lengths, two powder injection positions (PIP) at the moment of spark detonation, and two numbers of GDS shots with 6.66 Hz frequency were applied as variable parameters in the GDS process. Surface profile measurements were conducted by contact profilometry with the use of the TOPO-01 system and the Mitutoyo SJ 210 profilometer. The measured parameters were used to analyze surface topography in two-dimensional (2D) and three-dimensional (3D) systems. It was assumed that roughness can be regarded as a non-stationary parameter of variance in surface amplitude which is highly dependent on the sampling rate and spraying distance. Therefore, changes in surface amplitude parameters and functional properties were analyzed across segments with a length (ln) of 1.25, 4 and 12.5 mm. The development of the geometric structure of the surface was analyzed with the RMS (Root Mean Square) fractal method, and the geometric structure of the surface stretched by several orders of magnitude was evaluated based on the correlation between roughness (Rq), segment length (ln) and fractal dimension (D). The RMS method and the calculated fractal dimension (D) supported the characterization of the geometric structure of intermetallic Fe-Al protective coatings subjected to GDS under the specified process conditions based on the roughness profiles of surface segments with a different length (ln).

3

An analysis of non-isothermal primary crystallization kinetics of Fe95Si5 amorphous alloy

Frączyk Adam, Kuś Krzysztof, Wojtkowiak Adam

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2019

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nr 22(3)

237--247

EN

The paper describes the primary crystallization of metallic Fe95Si5 glass which was studied by differential scanning calorimetry (DSC) with non-isothermal methods. The activation energy of crystal transformation was calculated with the equations proposed by Kissinger, Mahadevan and a modified version of the equation developed by Augis and Bennett. Activation energy was determined at Ea = 242.0 - 254.2 kJ / mol, subject to the applied method. The Avrami exponent of crystallization in the amorphous phase n was determined in the range of n = 2.40 - 2.52, depending on the method of calculating the transformation of activation energy.