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Study of organosilicone fragmentation in plasma
Sahánková, Hana ; Studýnka, Jan (referee) ; Krčma, František (advisor)
This Bachelor Thesis deals on the study of organosilicone monomers in plasma. The dimethylphenylsilane (DMPS) was chosen as the organosilicone example. The theoretical part gives basic overview of plasmachemical processes and technologies used in present world. Some part is reserved for the description of plasma diagnostic basic methods as optical emission spectroscopy and mass spectroscopy. The experimental part is constituted from two different experiments. The first one was done as model experiment of DMPS fragmentation by electron beam of exact energy and it was completed at Faculty of Mathematics, Physics and Informatics in Bratislava. Results of these experiments brought a set of electron energies needed for the creation of various ionic fragments from the original molecule as well as the cross sections for their creation. The second part of the experiments was carried out under the inductively coupled RF low pressure plasma conditions during the deposition of DMPS based thin films. The plasma was monitored by optical emission spectroscopy at different discharge power. Various species were identified in the spectra. The calculation of plasma parameters and their comparision with the model experiment data will be subjects of the further work.
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Plasma-enhanced chemicial vapor deposition
Žák, Luboš ; Salyk, Ota (referee) ; Čech, Vladimír (advisor)
Theoretical part of diploma thesis was focused on the search of the state of knowledge in the area of plasma, plasma polymerization and characterization of thin films. Plasma-enhanced chemical vapor deposition (PECVD) was described in the experimental part together with selected analytical techniques. The technology with high level of reproducibility was reached by precise control of deposition conditions, monitoring of plasma, and analysis of plasma products using mass spectrometry. The obtained results demonstrated that the elemental composition, chemical structure, optical and mechanical properties of films were influenced by effective power used.
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Barriere layers for culture herritage objects preservation
Procházka, Michal ; Lehocký, Marián (referee) ; Zahoranová, Anna (referee) ; Krčma, František (advisor)
Every year, many archeological findings are discovered. It is necessary to document and conserve these items dug up from the ground. However, archeologists and conservators cannot handle such a big amount of newly found items. This work offers an alternative approach to standard conservation techniques, increasing the processing capacity and lowering the cost on items’ conservation. Studied alternative, mainly for protection of metallic artefacts, includes thin films based on parylene and organosilicons. Thin films were prepared on two experimental apparatuses. Parylene films were deposited by chemical vapour deposition (CVD). Final product was a thin film of parylene C. Organosilicon thin films were deposited via plasma enhanced chemical vapour deposition (PECVD). PECVD apparatus operates with capacitively coupled radiofrequently initiated plasma. Using hexamethyldisiloxane, thin films very similar to silicon dioxide were produced, thus called SiOx. Thin films were characterized by several methods and compared to standard treatment used by conservators – tannate layer, acrylic furnish Paraloid B72 and microcrystalline wax Revax 30. Parylene films showed excellent conformity and resistance to corrosion on iron substrate. First signs of corrosion were observed on layer of 5 µm thickness after 24 hours in salt fog. On samples coated by SiOx films, corrosion was spreading wide even during 1st hour of the corrosion test. Most probable cause was that SiOx film has thermal expansion coefficient different from iron substrate and due to this fact cracking occurs during cooling down of the treated substrate. On samples coated by standard treatment, corrosion occurred after 1-3 hours of the test. Oxygen transmission rate (OTR) measurements (performed on polypropylene substrate) confirmed good barrier properties of parylene C. Best parylene thin films had OTR approximately 170 cm3•m-2•atm-1•day-1. SiOx films reached good results with OTR 300 cm3•m-2•atm-1•day-1, compared to clean polypropylene substrate with OTR 1700 cm3•m-2•atm-1•day-1. Standard conservation layers could not be applied on polypropylene substrate, thus their OTR was not measured. We did not succeed in finding a substrate which is compatible for all types of treatments. Next, the study focused on combinations of thin films forming sandwich structures. All types let the corrosion attack the substrate during the 1st hour of the test. The cause was insufficient film thickness as well as crack ing of SiOx films due to different thermal expansion properties from the iron substrate. Although SiOx thin films were not deposited on substrate directly, they have excellent adhesion to parylenu and thus they could tear parylenu films due to thermal expansion. However, OTR measurements showed improvement in barrier properties. Multilayer parylene C–SiOx–parylene C–SiOx had OTR 5 cm3•m-2•atm-1•day-1. Final result is that parylene C thin films have better barrier properties than standard coatings and are suitable for conservation of metallic archaeological artefacts. SiOx films and multilayers showed poor anticorrosion protection of metallic substrates but they have good barrier and chemical properties in combination with other types of substrates. Mainly deposited on polymers, there is great potential for their application in many fields. Further research would be focused on new substrates for SiOx thin films and on the improvement of UV stability of parylene films.
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Barriere layers for culture herritage objects preservation
Procházka, Michal ; Lehocký, Marián (referee) ; Zahoranová, Anna (referee) ; Krčma, František (advisor)
Every year, many archeological findings are discovered. It is necessary to document and conserve these items dug up from the ground. However, archeologists and conservators cannot handle such a big amount of newly found items. This work offers an alternative approach to standard conservation techniques, increasing the processing capacity and lowering the cost on items’ conservation. Studied alternative, mainly for protection of metallic artefacts, includes thin films based on parylene and organosilicons. Thin films were prepared on two experimental apparatuses. Parylene films were deposited by chemical vapour deposition (CVD). Final product was a thin film of parylene C. Organosilicon thin films were deposited via plasma enhanced chemical vapour deposition (PECVD). PECVD apparatus operates with capacitively coupled radiofrequently initiated plasma. Using hexamethyldisiloxane, thin films very similar to silicon dioxide were produced, thus called SiOx. Thin films were characterized by several methods and compared to standard treatment used by conservators – tannate layer, acrylic furnish Paraloid B72 and microcrystalline wax Revax 30. Parylene films showed excellent conformity and resistance to corrosion on iron substrate. First signs of corrosion were observed on layer of 5 µm thickness after 24 hours in salt fog. On samples coated by SiOx films, corrosion was spreading wide even during 1st hour of the corrosion test. Most probable cause was that SiOx film has thermal expansion coefficient different from iron substrate and due to this fact cracking occurs during cooling down of the treated substrate. On samples coated by standard treatment, corrosion occurred after 1-3 hours of the test. Oxygen transmission rate (OTR) measurements (performed on polypropylene substrate) confirmed good barrier properties of parylene C. Best parylene thin films had OTR approximately 170 cm3•m-2•atm-1•day-1. SiOx films reached good results with OTR 300 cm3•m-2•atm-1•day-1, compared to clean polypropylene substrate with OTR 1700 cm3•m-2•atm-1•day-1. Standard conservation layers could not be applied on polypropylene substrate, thus their OTR was not measured. We did not succeed in finding a substrate which is compatible for all types of treatments. Next, the study focused on combinations of thin films forming sandwich structures. All types let the corrosion attack the substrate during the 1st hour of the test. The cause was insufficient film thickness as well as crack ing of SiOx films due to different thermal expansion properties from the iron substrate. Although SiOx thin films were not deposited on substrate directly, they have excellent adhesion to parylenu and thus they could tear parylenu films due to thermal expansion. However, OTR measurements showed improvement in barrier properties. Multilayer parylene C–SiOx–parylene C–SiOx had OTR 5 cm3•m-2•atm-1•day-1. Final result is that parylene C thin films have better barrier properties than standard coatings and are suitable for conservation of metallic archaeological artefacts. SiOx films and multilayers showed poor anticorrosion protection of metallic substrates but they have good barrier and chemical properties in combination with other types of substrates. Mainly deposited on polymers, there is great potential for their application in many fields. Further research would be focused on new substrates for SiOx thin films and on the improvement of UV stability of parylene films.
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Plasma-enhanced chemicial vapor deposition
Žák, Luboš ; Salyk, Ota (referee) ; Čech, Vladimír (advisor)
Theoretical part of diploma thesis was focused on the search of the state of knowledge in the area of plasma, plasma polymerization and characterization of thin films. Plasma-enhanced chemical vapor deposition (PECVD) was described in the experimental part together with selected analytical techniques. The technology with high level of reproducibility was reached by precise control of deposition conditions, monitoring of plasma, and analysis of plasma products using mass spectrometry. The obtained results demonstrated that the elemental composition, chemical structure, optical and mechanical properties of films were influenced by effective power used.
|
|
|
Study of organosilicone fragmentation in plasma
Sahánková, Hana ; Studýnka, Jan (referee) ; Krčma, František (advisor)
This Bachelor Thesis deals on the study of organosilicone monomers in plasma. The dimethylphenylsilane (DMPS) was chosen as the organosilicone example. The theoretical part gives basic overview of plasmachemical processes and technologies used in present world. Some part is reserved for the description of plasma diagnostic basic methods as optical emission spectroscopy and mass spectroscopy. The experimental part is constituted from two different experiments. The first one was done as model experiment of DMPS fragmentation by electron beam of exact energy and it was completed at Faculty of Mathematics, Physics and Informatics in Bratislava. Results of these experiments brought a set of electron energies needed for the creation of various ionic fragments from the original molecule as well as the cross sections for their creation. The second part of the experiments was carried out under the inductively coupled RF low pressure plasma conditions during the deposition of DMPS based thin films. The plasma was monitored by optical emission spectroscopy at different discharge power. Various species were identified in the spectra. The calculation of plasma parameters and their comparision with the model experiment data will be subjects of the further work.
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