Püskürtmeli Kurutma Ve Termal Bozunma Prosesleri İle Zno Esaslı Partiküllerin Ve Kompozit Yapıların Sentezlenmesi Ve Karakterizasyonu
Püskürtmeli Kurutma Ve Termal Bozunma Prosesleri İle Zno Esaslı Partiküllerin Ve Kompozit Yapıların Sentezlenmesi Ve Karakterizasyonu
thumbnail.default.placeholder
Tarih
2017-03-21
Yazarlar
Duman, Şeyma
Süreli Yayın başlığı
Süreli Yayın ISSN
Cilt Başlığı
Yayınevi
Fen Bilimleri Enstitüsü
Institute of Science and Technology
Institute of Science and Technology
Özet
Nanomalzemelerin fiziksel, kimyasal ve optik özelliklerinde boyutlarına bağlı oluşan değişiklikler, farklı fonksiyonel özelliklere sahip yeni malzemelerin geliştirilmesine olanak sağlamaktadır. Metal, seramik, polimer veya kompozit yapıda olabilen nano yapılı malzemelerin ve cihazların tasarlanmasını, üretilmesini ve uygulamasını kapsayan nanoteknoloji alanındaki gelişmeler için ilk adım nano yapılı partiküllerin sentezlenmesidir. Nano yapılı partiküller geniş bir kimyasal bileşim aralığında ve yapıda sentezlenebilmektedirler. Metal ve metal oksit nanoyapılı partiküller gösterdikleri önemli elektronik, optik, manyetik ve katalitik etkilerinden dolayı araştırmacıların yoğun ilgisini çekmektedirler. Çinko oksit (ZnO) yüksek iyoniklik ve yüksek bağlanma enerjisi, direk geçişli geniş bant aralığı gibi birçok özelliği barındırması sebebiyle elektriksel, manyetik ve optik uygulamalarda yaygın olarak çalışılmakta olup birçok mühendislik uygulamaları için ekonomik olarak tedarik edilebilen bir üründür. Bunun yanında, ZnO’in antibakteriyel ve antimikrobiyel davranışı ve birçok uygulamada sağlığa zarar vermeden kullanılabilirliği uygulama alanlarını genişletmektedir. İstenilen boyut ve şekillerde ZnO nanopartiküllerin elde edilmesine olanak sağlayan sentez yöntemlerinin karmaşık sistem gerektirmeden uygulanabilir ve ekonomik olması, homojen bir yapı oluşturması, yüksek miktarlarda üretim sağlaması önemli bir diğer husustur. Püskürtmeli kurutma prosesinin en önemli avantajı kontaminasyona maruz kalmadan gıda, medikal, seramik alanlarında kullanılan tozların elde edilmesidir. Termal bozunma prosesi, aşağıdan yukarıya yaklaşımı içinde yer almakta, ancak homojen dağılım gerçekleştirmekte sorunlar yaşanmaktadır. Bu dezavantajı gidermek ve çözelti içinde metal iyon hareketlerini dengeli dağıtarak homojen dağılımlı partiküller elde etmek amacıyla bu proses öncesinde püskürtmeli kurutma prosesi uygulanmıştır. Uygulaması kolay ve maliyeti düşük olan termal bozunma prosesi ile homojen dağılmış tozların sentezi tamamlanmış olmaktadır. Bu çalışmanın birinci kısmında, nanopartikül sentezinde deneysel parametrelerin etkisine değinilmiştir. Deney parametreleri olarak püskürtmeli kurutucunun çözelti besleme debisi, kurutma havası sıcaklığı ve debisi gibi farklı çalışma şartlarında, farklı konsantrasyon miktarlarında ve farklı pH değerlerinde tozlar hazırlanmıştır. Püskürtülerek kurutulmuş çinko asetat tozların kurutma parametrelerinden ne ölçüde etkilendiğinin belirlenmesi için nem tayini, görünür yoğunluğu ve partikül morfolojileri tespit edilmiştir. Ardından termal bozunma prosesi uygulanmış ve sentezlenen ZnO nanopartiküllerin morfoloji, yoğunluk ve partikül boyut özellikleri incelenmiştir. Çalışma şartlarının, konsantrasyonun ve pH’ın püskürtmeli kurutulmuş tozların ve ZnO nanopartiküllerin morfoloji ve partikül boyut özellikleri üzerine etkilerinin olduğu belirlenmiştir. Optimum olarak belirlenen deney parametrelerinde hazırlanan tozlar farklı sıcaklıklarda sentezlenerek ZnO nanopartiküller elde edilmiştir. ZnO nanopartiküllerin morfoloji ve partikül boyut özelliklerinin belirlenmesi için de; faz analizi, kristal boyutu, partikül boyutu ve partikül morfolojileri tespit edilmiş ve optik özellikleri incelenmiştir. Deney parametreleri ve sıcaklıktaki değişikliklerin ZnO nanopartiküllerin morfoloji ve partikül boyut özelliklerini değiştirdiği tespit edilmiştir. ZnO nanopartiküllere uygun katkılamalar yapılarak yapısal ve optik özellikleri iyileştirilebilmektedir. Bu nedenle ZnO ile yapılan çok sayıda çalışma olmasına rağmen, hala farklı metallerin katkısı ile ZnO esaslı yeni malzemelerin sentezlenmesine devam edilmektedir. Bu çalışmanın ikinci kısmında, gümüş nitrat, mangan asetat, kobalt asetat ve borik asit gibi metal bazlı katkıların ilavesi ile ZnO esaslı nanopartiküller ve PVA katkılı türevleri aynı yöntem kullanılarak sentezlenmiştir. Elde edilen ZnO esaslı nanopartiküllerin yapısal ve optik özellikleri katkı konsantrasyonu ve sıcaklığa bağlı değişimi sentezlenen optimum ZnO nanopartikülleri ile kıyaslanarak incelenmiştir. XRD ve elektron mikroskop yöntemleri kullanılarak yapılan kapsamlı yapısal analizlerle her bir metal iyonunun ZnO kristal yapısına yerleşme mekanizması ve kristal yapıda oluşturdukları değişimler belirlenmiştir. Ek olarak, metalik iyon ilavelerinin ZnO’in optik özelliklere etkisi gözlenmiştir. ZnO nanopartiküllerin boyut ve şekilleri termal bozunma sıcaklığının seçimi, PVA miktarı ve kullanılan konsantrasyon miktarı ile kontrol edilmiştir. Bu değişkenlerin temel olarak sentez sırasında oluşmakta olan ZnO kristalleri ve organik moleküller arasındaki adsorpsiyon farklılaşmalara neden olduğu ve ZnO esaslı nanopartiküller için boyutsal ve şekilsel değişimlerin sağlanabileceği ortaya konulmuştur. Bu çalışmanın üçüncü kısmında ise, ZnO katkılı kompozit yapılar üretilmiştir. Ana malzeme olarak hidroksiapatit ve kalsiyum fosfat tribazik gibi kalsiyum fosfat esaslı biyoseramik tozları tercih edilmiştir. Kalsiyum fosfat seramiklerin düşük mekanik özelliklere, rijit ve gevrek bir yapıya sahip olduğu bilinmektedir. Yüksek mekanik mukavemeti, tokluğu ve insan sağlığına zararlı olmaması nedeniyle, kalsiyum fosfat esaslı biyoseramiklerin ikincil fazı olarak ticari ZnO tozu ve sentezlenen ZnO nanopartikülü kullanılmıştır. Püskürtmeli kurutma yöntemi ile bu katkı malzemeleri kalsiyum fosfat esaslı biyoseramiklere ilave edilerek homojen dağılımlı ZnO katkılı HA ve ZnO katkılı CPT kompozit tozları hazırlanmıştır. Ayrıca kompozit tozlara PVA katkısı yapılmış ve püskürtmeli kurutma yöntemiyle granülleştirme işleminin ilgili kompozit tozların paketlenme özelliklerine de ciddi oranda etki ettiği belirlenmiştir. Bu bağlamda özellikle PVA katkılı sistemlerde presleme sonrasında, katkısız duruma kıyasla ciddi yoğunluk artışları tespit edilmiştir. ZnO katkısının kompozit yapılara etkisi araştırılmış ve mekanik özelliklerinin geliştiği tespit edilmiştir. Sinterleme sıcaklığındaki artış, ZnO ve PVA katkılı kompozit yapıların yoğunluğunun ve mekanik özelliklerinin kontrol edilebileceğini ortaya koymuştur.
Nanotechnology offers lots of innovation that simplify the daily life of human being. Reduction of materials to nanosize levels is a major factor to determine its physical, chemical, and biological features. Nanosized materials can be in a form of metal, ceramic, organic molecular, polymeric or composite structure. Synthesis of nano-structured particles is the first step, for the development of coating, synthesis, and functional use of nano-structured materials and devices in nanotechnology area. Nano-structured particles can be synthesized in a wide range of chemical compositions and structures. Major nanostructure samples are of nanotubes, nanowires, nano-rods, and nanofibers. Nanoparticle synthesis methods are important in the development of nano-structured materials and can be examined under two main approaches as bottom-up and top-down. Nanoparticles are obtained by reducing the volume of the material to nano-size by means of applying a mechanical impact to bulk material as a top-down approach and by applying physicochemical methods to molecular material as a bottom-up approach; The particle morphology, particle size, surface area, crystal structure and the amount depending on the synthesis method and conditions affect the optical properties of the material. Nano-structured particles that are made of metal and metal oxides attract the attention of researchers due to their important electronic, optical, magnetic, and catalytic properties. Nanoparticle materials that have the highest importance are metal oxides as zinc oxide, alumina, titanium dioxide, and iron oxide. Zinc oxide (ZnO) has been studied extensively in magnetic, electrical and optical applications due to its direct and wide band gap (3.37 eV), high ionicity and high exciton binding energy (60 meV) as well as low cost and hygienic features. Structural and optical properties of ZnO nanoparticles depend on particle size, morphology and chemical compositions. With regard to this point, it is important to synthesize ZnO nanoparticles in a controlled and repeatable manner. Applicable to any size and shape without a complex synthesis mechanism that allows obtaining ZnO nanoparticles with low cost and homogeneous structures by providing the production in large quantities is another important matter. The nanosized ZnO is used in many optoelectronic, magnetic, electronic, photocatalytic and catalytic applications such as gas sensors, catalysts, UV absorbers and fuel cells. The synthesis of pure ZnO nanostructures was achieved by first spray drying and then thermal decomposition processes. Thermal decomposition is a bottom-up approach posing problems in obtaining a homogeneous distribution. Before the thermal decomposition process, spray-drying process has been applied to obtain homogenous spread of particles by distributing the balanced movement of metal ions in solution. The main advantage of spray-drying process is to obtain powder used in food, medical, and ceramic fields without exposing to contamination. Thermal decomposition process is an easy and low cost application providing a synthesis of homogenously distributed powder structures. Compared to undoped ZnO, doped ZnO offer the opportunity of using the dopant adjusting their optical, magnetical and electronical properties. Therefore, in addition to known advantages, the nanomaterials possess improved size, shape, and surface properties, while the dopants provide additional flexibility by bringing in new functionalities to change their properties. The characteristics of various transition metals (TMs) or transition metal oxides (TMOs) as silver, copper and boron-rich compound depend on the type of TM and its amount. Besides, TMs are advanced materials because of their unique properties and potential applications as microelectronics, optoelectronics, catalysis, photocatalysis, magnetic materials, information storage and other applications. Mn, Co and Ag nanoparticles have been widely used for optic and bio applications due to high optical and antibacterial features. Boron or boron rich oxide doped ZnO nanoparticles improve characteristics of the structure specifically the optical properties and the photocatalytic activity. Composites are multi-phase structures containing a reinforced phase dispersed within a main phase. Ceramic matrix composites made of composite structures exhibit high fracture toughness and hardness properties. Ceramics is an important material group for mechanical applications. Ceramic materials as calcium phosphate exhibit poor mechanical properties, as high rigidity and brittle behavior. Zn and ZnO pose high antibacterial and mechanical performance in the presence of a supporting structure. Poly-vinyl alcohol (PVA) is a favorable polymer due to its water-solubility, nontoxic and degradable features. It improves mechanical performance as a secondary phase when combined with calcium phosphate based bio-ceramic, because ZnO and PVA exhibit high mechanical strength, toughness, and no interaction with human body. In the first part of this study, after powder spraying of Zn(Ac)2 from a laboratory scale spray dryer, ZnO synthesis was executed by thermal decomposition process. The effect of operating conditions such as a solution feed rate, air-drying temperature and powder flow were obtained and the properties of the synthesized ZnO nanoparticles were observed. Spray drying of zinc acetate powder was accomplished by passing through a process temperature of 300 °C, heating rate of 2 °C/min and a 12 hours maturing time for thermal decomposition of ZnO nanoparticles. Moisture measurement, apparent density, phase analysis, particle size and particle morphology studies were performed to determine the effect of drying parameters on physical properties of spray-dried zinc acetate powder. Concentration and pH test parameters were obtained for the powder and sintered ZnO nanoparticles affecting physical properties. Moisture analysis, apparent density, phase analysis, particle size and particle morphology analysis were also performed to investigate their effect on physical properties. Operating conditions of the spray dryer, the concentration and pH of the powder and the ZnO nanoparticles were recorded due their effect on physical properties. ZnO nanoparticles prepared with optimum experimental parameters were synthesized at different temperatures as 300°C, 400°C and 500°C. The phase analysis, crystal size, analysis of the particle size and morphology was performed to determine the physical properties of the synthesized ZnO nanoparticles. By proper doping to ZnO nanoparticles, the structural, optical, antibacterial and electrical properties can be improved. Therefore, although there are many studies relevant to ZnO, there is still a wide range of opportunities for synthesis of ZnO doped materials. In the second part of this study, ZnO nanocomposite particles were synthesized by doping with silver (Ag), manganese (Mn), cobalt (Co) and boron-rich oxide (B7O) and PVA derivations. Different temperatures such as 300°C, 400°C, and 500°C were applied for each doping experiment. The resulting structural and optical properties of ZnO nanocomposite particles based on doping concentration and temperature dependent changes were examined in comparison with the optimal synthesized ZnO nanoparticles. The settlement mechanism of each metal ion into ZnO crystal structure and the changes they cause in the crystal structure is determined using XRD and scanning electron microscopy. Crystalline size is also calculated with the help of well-knowns Debye-Scherrer and Williamson-Hall equations. Additionally, the optical properties of ZnO are also studied due to its effect on metallic ions. Selection of the size and shape of ZnO nanoparticles, thermal decomposition temperature was controlled by the amount of PVA and the rate of the concentration. These variables mainly affect ZnO crystals formed during the synthesis and differentiation been caused by the adsorption between the organic molecules and it has been revealed that dimensional and conformational change of ZnO based nanocomposite particles can be achieved. In the third part of this study, ZnO doped composite structures are produced. Bio-ceramics powder based calcium phosphate, such as hydroxyapatite and calcium phosphate dibasic is preferred as the base material. Commercial ZnO powder and synthesized ZnO nanoparticles were used to investigate the effect of ZnO on the composite structure produced by sintering method. Also, the contribution of PVA concentration to the composite powder and the effect of the granulation process via spray-drying method on the packaging properties of the composite powder has been shown to infer significant relevance. In this context, especially after pressing the PVA doped systems, significant increase in density compared to the pure state was observed. Calcium phosphate ceramics pose low mechanical properties, rigid, and brittle structure. High mechanical strength, toughness, detrimental effect to human health, calcium phosphate based bio-ceramics, ZnO was used as a secondary phase yielding improved mechanical properties for the sintered product. The increase in sintering temperature revealed the controllability of the density and mechanical properties of an optimal ZnO and PVA composition.
Nanotechnology offers lots of innovation that simplify the daily life of human being. Reduction of materials to nanosize levels is a major factor to determine its physical, chemical, and biological features. Nanosized materials can be in a form of metal, ceramic, organic molecular, polymeric or composite structure. Synthesis of nano-structured particles is the first step, for the development of coating, synthesis, and functional use of nano-structured materials and devices in nanotechnology area. Nano-structured particles can be synthesized in a wide range of chemical compositions and structures. Major nanostructure samples are of nanotubes, nanowires, nano-rods, and nanofibers. Nanoparticle synthesis methods are important in the development of nano-structured materials and can be examined under two main approaches as bottom-up and top-down. Nanoparticles are obtained by reducing the volume of the material to nano-size by means of applying a mechanical impact to bulk material as a top-down approach and by applying physicochemical methods to molecular material as a bottom-up approach; The particle morphology, particle size, surface area, crystal structure and the amount depending on the synthesis method and conditions affect the optical properties of the material. Nano-structured particles that are made of metal and metal oxides attract the attention of researchers due to their important electronic, optical, magnetic, and catalytic properties. Nanoparticle materials that have the highest importance are metal oxides as zinc oxide, alumina, titanium dioxide, and iron oxide. Zinc oxide (ZnO) has been studied extensively in magnetic, electrical and optical applications due to its direct and wide band gap (3.37 eV), high ionicity and high exciton binding energy (60 meV) as well as low cost and hygienic features. Structural and optical properties of ZnO nanoparticles depend on particle size, morphology and chemical compositions. With regard to this point, it is important to synthesize ZnO nanoparticles in a controlled and repeatable manner. Applicable to any size and shape without a complex synthesis mechanism that allows obtaining ZnO nanoparticles with low cost and homogeneous structures by providing the production in large quantities is another important matter. The nanosized ZnO is used in many optoelectronic, magnetic, electronic, photocatalytic and catalytic applications such as gas sensors, catalysts, UV absorbers and fuel cells. The synthesis of pure ZnO nanostructures was achieved by first spray drying and then thermal decomposition processes. Thermal decomposition is a bottom-up approach posing problems in obtaining a homogeneous distribution. Before the thermal decomposition process, spray-drying process has been applied to obtain homogenous spread of particles by distributing the balanced movement of metal ions in solution. The main advantage of spray-drying process is to obtain powder used in food, medical, and ceramic fields without exposing to contamination. Thermal decomposition process is an easy and low cost application providing a synthesis of homogenously distributed powder structures. Compared to undoped ZnO, doped ZnO offer the opportunity of using the dopant adjusting their optical, magnetical and electronical properties. Therefore, in addition to known advantages, the nanomaterials possess improved size, shape, and surface properties, while the dopants provide additional flexibility by bringing in new functionalities to change their properties. The characteristics of various transition metals (TMs) or transition metal oxides (TMOs) as silver, copper and boron-rich compound depend on the type of TM and its amount. Besides, TMs are advanced materials because of their unique properties and potential applications as microelectronics, optoelectronics, catalysis, photocatalysis, magnetic materials, information storage and other applications. Mn, Co and Ag nanoparticles have been widely used for optic and bio applications due to high optical and antibacterial features. Boron or boron rich oxide doped ZnO nanoparticles improve characteristics of the structure specifically the optical properties and the photocatalytic activity. Composites are multi-phase structures containing a reinforced phase dispersed within a main phase. Ceramic matrix composites made of composite structures exhibit high fracture toughness and hardness properties. Ceramics is an important material group for mechanical applications. Ceramic materials as calcium phosphate exhibit poor mechanical properties, as high rigidity and brittle behavior. Zn and ZnO pose high antibacterial and mechanical performance in the presence of a supporting structure. Poly-vinyl alcohol (PVA) is a favorable polymer due to its water-solubility, nontoxic and degradable features. It improves mechanical performance as a secondary phase when combined with calcium phosphate based bio-ceramic, because ZnO and PVA exhibit high mechanical strength, toughness, and no interaction with human body. In the first part of this study, after powder spraying of Zn(Ac)2 from a laboratory scale spray dryer, ZnO synthesis was executed by thermal decomposition process. The effect of operating conditions such as a solution feed rate, air-drying temperature and powder flow were obtained and the properties of the synthesized ZnO nanoparticles were observed. Spray drying of zinc acetate powder was accomplished by passing through a process temperature of 300 °C, heating rate of 2 °C/min and a 12 hours maturing time for thermal decomposition of ZnO nanoparticles. Moisture measurement, apparent density, phase analysis, particle size and particle morphology studies were performed to determine the effect of drying parameters on physical properties of spray-dried zinc acetate powder. Concentration and pH test parameters were obtained for the powder and sintered ZnO nanoparticles affecting physical properties. Moisture analysis, apparent density, phase analysis, particle size and particle morphology analysis were also performed to investigate their effect on physical properties. Operating conditions of the spray dryer, the concentration and pH of the powder and the ZnO nanoparticles were recorded due their effect on physical properties. ZnO nanoparticles prepared with optimum experimental parameters were synthesized at different temperatures as 300°C, 400°C and 500°C. The phase analysis, crystal size, analysis of the particle size and morphology was performed to determine the physical properties of the synthesized ZnO nanoparticles. By proper doping to ZnO nanoparticles, the structural, optical, antibacterial and electrical properties can be improved. Therefore, although there are many studies relevant to ZnO, there is still a wide range of opportunities for synthesis of ZnO doped materials. In the second part of this study, ZnO nanocomposite particles were synthesized by doping with silver (Ag), manganese (Mn), cobalt (Co) and boron-rich oxide (B7O) and PVA derivations. Different temperatures such as 300°C, 400°C, and 500°C were applied for each doping experiment. The resulting structural and optical properties of ZnO nanocomposite particles based on doping concentration and temperature dependent changes were examined in comparison with the optimal synthesized ZnO nanoparticles. The settlement mechanism of each metal ion into ZnO crystal structure and the changes they cause in the crystal structure is determined using XRD and scanning electron microscopy. Crystalline size is also calculated with the help of well-knowns Debye-Scherrer and Williamson-Hall equations. Additionally, the optical properties of ZnO are also studied due to its effect on metallic ions. Selection of the size and shape of ZnO nanoparticles, thermal decomposition temperature was controlled by the amount of PVA and the rate of the concentration. These variables mainly affect ZnO crystals formed during the synthesis and differentiation been caused by the adsorption between the organic molecules and it has been revealed that dimensional and conformational change of ZnO based nanocomposite particles can be achieved. In the third part of this study, ZnO doped composite structures are produced. Bio-ceramics powder based calcium phosphate, such as hydroxyapatite and calcium phosphate dibasic is preferred as the base material. Commercial ZnO powder and synthesized ZnO nanoparticles were used to investigate the effect of ZnO on the composite structure produced by sintering method. Also, the contribution of PVA concentration to the composite powder and the effect of the granulation process via spray-drying method on the packaging properties of the composite powder has been shown to infer significant relevance. In this context, especially after pressing the PVA doped systems, significant increase in density compared to the pure state was observed. Calcium phosphate ceramics pose low mechanical properties, rigid, and brittle structure. High mechanical strength, toughness, detrimental effect to human health, calcium phosphate based bio-ceramics, ZnO was used as a secondary phase yielding improved mechanical properties for the sintered product. The increase in sintering temperature revealed the controllability of the density and mechanical properties of an optimal ZnO and PVA composition.
Açıklama
Tez (Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2016
Thesis (Ph.D.) -- İstanbul Technical University, Institute of Science and Technology, 2016
Thesis (Ph.D.) -- İstanbul Technical University, Institute of Science and Technology, 2016
Anahtar kelimeler
çinko oksit,
püskürtmeli kurutucu,
termal bozunma,
sentez,
karakterizasyon,
zinc oxide,
spray dryer,
thermal decomposition,
synthesis,
characterization