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Publikācija: Synthesis and Properties of Ceramic Structure Using both Biomimetic and Sol-gel Methods

Publication Type Publications in RTU scientific journal
Funding for basic activity Unknown
Defending: ,
Publication language Latvian (lv)
Title in original language Keramikas struktūras iegūšana un īpašības ar biomimētikas un sola-gēla metodi
Title in English Synthesis and Properties of Ceramic Structure Using both Biomimetic and Sol-gel Methods
Field of research 2. Engineering and technology
Sub-field of research 2.5 Materials engineering
Authors Inna Juhņeviča
Gundars Mežinskis
Inga Kļaviņa
Aļona Gabrene
Keywords high temperature ceramic matrix composites, SiC ceramics with oriented porous structure, sol-gel system
Abstract Pieaugošā interese un jaunu biomateriālu pieprasījums sekmē materiālu sintēzi no dabiskām un sintētiskām izejvielām, lai radītu materiālus ar plaši pielietojamām īpašībām. SiC keramikas iegūšanai izmantoja sola iefiltrēšanas metodi dažāda veida koksnes materiāliem. Viens no veiksmīgākajiem sola-gēla sintēzes ceļiem ir tetraetoksisilāna un titāna izoproksīda izmantošana. Iegūti porainie lazdas paraugi ar augstu stiprību un elastības moduli, kuros dominē SiC kristāliskā fāze.
Abstract in English Natural materials can be used as a source of new technologies for acquisition of materials. The principles of those new technologies are imitation of nature. Such a technology as bio-template is mainly used, which allows transforming bio-organic substances into high-strength and light-weight microcellular ceramic composites. The SiC ceramics is useful for new technical needs. It can be made by gas or sol infiltration. According to literature, understand conclusion can be made that sol-gel technology is a very progressive method. Hydrolysing ability of TOES under the condition of water vapour determines the stage of crystal formation. A very wide range of information is available about procuring of the SiC ceramics by the gas infiltration method under high pressure, which is a relatively expensive method compared to the sol infiltration method in air atmosphere. The solution of ethanol-water dissolves a lignin and promotes the formation of individual cells along a cross-section. If samples are treated with 5% NaOH liquid, then their mass decreases a little bit; this can be affected by the activation and removal of -OH groups. It is hard to treat pressed lichen samples, because of their solving process. The 3-aminopropiltriethoksisisilane can be better infiltrated in samples, which were swelled in 60% ethanol-water liquid, compared to samples in 96% ethanol. Hazelnut-tree samples had the best results – 93.38 because of successful swelling in 60% ethanol – water liquid (compared to other type of wood) changed the structure and opened the capillaceous tubes. The sol infiltrated intensively for the first 5 days, but at repeated infiltration the proportion of increase was not so high anymore. The increase decreased approximately by 1/3 with each next cycle; this could be explained by the fact that samples became harder after each pyrolysis and there were not left any elastic bonds, but mostly the pores were already filled. However, the solid particles of sol continued to increase volumetric capacity in samples, even more than in the first infiltration cycle; the reason was the formation of crystalline centres. The process of hydrolysis is necessary for extra crystallization promotion. The samples treated three times and pyrolysed in inert atmosphere at 1450 °C gave cristobalite, anatase and very significant SiC; however, the samples, which were treated in air atmosphere, gave only cristobalite, anatase and rutile. Organic part controls the shape and direction of crystals made by crystallization processes; it can even determine the structure of crystals. The photos of SEM show that in wood there are regular, thread-like and oval crystals.
Reference Juhņeviča, I., Mežinskis, G., Kļaviņa, I., Gabrene, A. Synthesis and Properties of Ceramic Structure Using both Biomimetic and Sol-gel Methods. Materials Sciences and Applied Chemistry. Vol.27, 2013, pp.5-10. ISSN 14077353.
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