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Nickel alloy overlay welding parameters optimalization
Lauš, Lukáš ; Kubíček, Jaroslav (referee) ; Sigmund, Marian (advisor)
The aim of these master's thesis is to choose and optimize parameters of the Venturi tube throat weld cladding. The Venturi tube is made from carbon steel ASME SA-106 Grade C. The weld cladding is performed by plasma transferred arc welding. The throat is weld overlaid with nickel base powder Inconel 625. The overlays are made without oscilation. The main requirement was to find a maximum possible powder feed rate and others welding parameters to develop maximum welding speed and productivity on automat. Visual and penetrant testing on the overlays were performed. Metalographic samples were prepared. On the samples was meassured dilution, overlay thickness and width of the heat affected zone. Results are compared with parameters succesfully used in the cooperating company.
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Replacement of nickel alloy overlay by manganese alloy overlay
Hlobil, Albert ; Kubíček, Jaroslav (referee) ; Sigmund, Marian (advisor)
The thesis is focused on the issue of tuning the welding process of the 18.8. Mn alloy using the method 152. The welded component is the cylindrical throat of a Venturi tube made of ASME SA-106 Grade C carbon steel. A series of welds were performed, which were qualitatively evaluated and compared. Metallographic sections were made, and the dilution, excess, and width of the heat-affected zone were determined. Evaluation of microstructure and microhardness were also performed. Based on the tests performed, suitable welding process parameters were used. For comparison, a test for chemical and salt mist corrosion was undertaken, where the corrosion resistance of the 18.8. Mn alloy weld was compared to Inconel 625 alloy.
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Nickel alloy overlay welding parameters optimalization
Lauš, Lukáš ; Kubíček, Jaroslav (referee) ; Sigmund, Marian (advisor)
The aim of these master's thesis is to choose and optimize parameters of the Venturi tube throat weld cladding. The Venturi tube is made from carbon steel ASME SA-106 Grade C. The weld cladding is performed by plasma transferred arc welding. The throat is weld overlaid with nickel base powder Inconel 625. The overlays are made without oscilation. The main requirement was to find a maximum possible powder feed rate and others welding parameters to develop maximum welding speed and productivity on automat. Visual and penetrant testing on the overlays were performed. Metalographic samples were prepared. On the samples was meassured dilution, overlay thickness and width of the heat affected zone. Results are compared with parameters succesfully used in the cooperating company.
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Vascular disorders of gastrointestinal tract - Diagnostics and endovascular therapy
MOKRÁ, Michaela
An important group of diseases affecting gastrointestinal tract is derived from impaired function of the blood vessels. These disorders involve bleeding (arterial and venous), aneurysms and intestinal ischaemia. Interventional approaches to treat gastrointestinal haemorrhage differ in arterial and venous bleedings. In treatment of arterial bleeding, embolization techniques are utilized for selective occlusion of a damaged artery. In case of venous varices, transjugular intrahepatic portosystem shunt (TIPS) must be introduced. Chronic mesenteric ischaemia is relieved by angioplasty with a stent placement. Endovascular extraction in acute intestinal ischaemia is performed with aspiration thrombectomy of the blood clot at the site of peripheral vascular occlusion. In our department, we treated 99 patients with disorders of gastrointestinal blood vessels in the course of two years. In 27 patients, we searched for the cause of arterial bleeding (in 33.3%, the bleeding was not confirmed). We performed 24 embolizations. In 55 patients, TIPS was placed; of these, additional embolization of portosystemic collateral was performed in 44 patients. Two patients suffering with mesenteric ischaemia were treated with PTA and stent placement. Seven patients with intestinal ischaemia were treated with the use of aspiration thrombectomy with a promising result - a complete recanalization was reached in 4 cases. Nowadays, endovascular therapy is a method of choice in therapy of vascular disorders of the gastrointestinal tract. In correct indications, endovascular therapy represents a save and effective method that shows a relatively good technical and clinical efficacy.
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