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Influencing the surface roughness of materials created by the SLM technique and the influence of roughness on macroscopic properties
Rotter, Marek ; Havlík, Petr (referee) ; Jan, Vít (advisor)
Theses resumes the principle of SLM method and submits the most used materials for this technology and its properties. The main issue is influencing the surface roughness of these materials, when the electro-chemical polishing in the concentrated sulfuric acid was used with five difference options. It was observed, that the roughness is caused by two factors, fused nonmelted grains of metal powder and layered structure. Polishing at 8 V, 0,5 A and after 40 min was the best results, when the smooth wave surface was achieved. The Ra parameter descended from initial 5,0 m to 3,9 m after this polishing. One of the factors, which causes the high roughness, was eliminated.
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Optimization of a debinding procedure for objects prepared by 3D printing of the low loaded photopolymeric ceramic suspensions
Rotter, Marek ; Roleček, Jakub (referee) ; Spusta, Tomáš (advisor)
Digital Light Processing (DLP) is one of the additive manufacturing methods suitable for preparing ceramic objects. The most important part of this manufacturing process is debinding, which eliminates cracks and defects due to the controlled transport of organic additives from inside to outside. Optimization of the debinding procedure of green bodies from suspension with loading 33.6 vol.% ZrO2 was accomplished for obtaining samples with maximal density and minimum defects. Samples with dimensions 14x14x15 mm were divided into nine groups with unequal debinding procedures. Each group has different heating rates (three heating rates) and atmosphere types (air, nitrogen, vacuum). The group contains six samples with wall thicknesses of 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm and 4.0 mm. Overall 54 samples were obtained. Evaluation of debinding groups included mass loss after debinding, after sintering and whole mass loss, visual observation of defects, calculation of relative density and porosity and shrinkage of samples. The most optimal debinding procedure takes 12 hours 30 min and it was performed under a vacuum. The average relative density of prepared samples was 98.4 ± 0.1 % and hardness HV1 was 1366 ± 17. Shrinkage in the cross-sectional direction reached 28 %, respectively 29 % in the printing direction. If stress concentrators are eliminated, this cycle provides good samples with 1 – 3 mm thick walls.
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Influencing the surface roughness of materials created by the SLM technique and the influence of roughness on macroscopic properties
Rotter, Marek ; Havlík, Petr (referee) ; Jan, Vít (advisor)
Theses resumes the principle of SLM method and submits the most used materials for this technology and its properties. The main issue is influencing the surface roughness of these materials, when the electro-chemical polishing in the concentrated sulfuric acid was used with five difference options. It was observed, that the roughness is caused by two factors, fused nonmelted grains of metal powder and layered structure. Polishing at 8 V, 0,5 A and after 40 min was the best results, when the smooth wave surface was achieved. The Ra parameter descended from initial 5,0 m to 3,9 m after this polishing. One of the factors, which causes the high roughness, was eliminated.
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