Mechanical compatibility of sol–gel annealing with titanium for orthopaedic prostheses

Sol–gel processing is an attractive method for large-scale surface coating due to its facile and inexpensive preparation, even with the inclusion of precision nanotopographies. These are desirable traits for metal orthopaedic prostheses where ceramic coatings are known to be osteoinductive and the effects may be amplified through nanotexturing. However there are a few concerns associated with the application of sol–gel technology to orthopaedics. Primarily, the annealing stage required to transform the sol–gel into a ceramic may compromise the physical integrity of the underlying metal. Secondly, loose particles on medical implants can be carcinogenic and cause inflammation so the coating needs to be strongly bonded to the implant. These concerns are addressed in this paper. Titanium, the dominant material for orthopaedics at present, is examined before and after sol–gel processing for changes in hardness and flexural modulus. Wear resistance, bending and pull tests are also performed to evaluate the ceramic coating. The findings suggest that sol–gel coatings will be compatible with titanium implants for an optimum temperature of 500 °C

PRELIMINARY STUDY FOR USING VINYLTRIACETOXYSILANE AS PRECURSOR IN ENZYME IMMOBILIZATION BASED ON SOL-GEL METHOD

During the last years, sol-gel technology has become a well-established method for the preparation of catalytic active monoliths, bulk, particles and thin films. One reason for the increasing research activities in this field is the opportunity to obtain versatile hybrid materials by incorporation of different molecules, like dyes, enzymes, whole cells, chemicals and drugs. The aim of this research was to evaluate the suitability of vinyltriacetoxysilane (VTAS) as precursor in sol-gel enzyme immobilization and the physicochemical characterization of the final products (silica xerogels)

Sol-gel synthesis and properties of piezoceramic nanoparticles on the base of (BaxCa1-x)(TiyZr1-y)O3

Tématem práce byla sol-gel syntéza nanočástic piezokeramiky na bázi BaxCa1-xTiyZr1-yO3 (BCTZ), příprava slinutých vzorků a analýza jejich struktury a vlastností. V teoretické části byly shrnuty poznatky o piezoelektrických vlastnostech keramických materiálů a jejich přípravě. V experimentální části byla popsána sol-gel syntéza nanočástic BCTZ, u kterých bylo hodnoceno fázové složení a velikost částic. Dále bylo popsáno lisování a slinování BCTZ vzorků a studium jejich vlastností.The aim of the work was sol-gel synthesis of piezoceramic nanoparticles on the base of BaxCa1-xTiyZr1-yO3 (BCTZ), preparation of sintered samples and analysis of their structure and properties. Theoretical part includes information about piezoelectricity, piezoelectric materials and preparation of ceramics. Experimental part describes sol-gel synthesis of BCTZ nanoparticles and achieved phase composition and particle size. The next topic of experimental part was preparation of sintered BCTZ samples and analysis of their properties.

Ultrapure glass optical waveguide development in microgravity by the sol-gel process

Multicomponent, homogeneous, noncrystalline oxide gels can be prepared by the sol-gel process and these gels are promising starting materials for melting glasses in the space environment. The sol-gel process referred to here is based on the polymerization reaction of alkoxysilane with other metal alkoxy compounds or suitable metal salts. Many of the alkoxysilanes or other metal alkoxides are liquids and thus can be purified by distillation. The use of gels offers several advantages such as high purity and lower melting times and temperatures. The sol-gel process is studied for utilization in the preparation of multicomponent ultrapure glass batches for subsequent containerless melting of the batches in space to prepare glass blanks for optical waveguides

Bahan Penderia untuk Pengesanan Aluminium Berasaskan Reagen Kolorimetrik Terdop dalam Filem Sol-Gel

Sol-gel technique was used in this study for sensing material preparation which could be used for aluminium detection in aqueous environment. Two organic reagents i.e. eriochrome cyanine R (ECR) and chrome azurol S (CAS), which are sensitive to aluminium were used in this study. The precursors used for the sol-gel solution preparation were tetraethyl orthosilicate (TEOS), water and ethanol in the volume ratio of 30:31:30. Dip-coating method was used to deposit the sol-gel solution onto microscope slide glass support to produce a thin sol-gel film. The study shows that the immobilised reagents have a good photo-stability, still maintaining their chemical properties as in free solution and regenerable by using NaF solution. The study also indicates that the reagen doped in sol-gel film still react with the analyze and could be potentially used as sensing material for aluminium detection

Modification of hemp shiv properties using water-repellent sol–gel coatings

For the first time, the hydrophilicity of hemp shiv was modified without the compromise of its hygroscopic properties. This research focused on the use of sol–gel method in preparation of coatings on the natural plant material, hemp shiv, that has growing potential in the construction industry as a thermal insulator. The sol–gel coatings were produced by cohydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) using an acidic catalyst. Methyltriethoxysilane (MTES) was added as the hydrophobic precursor to provide water resistance to the bio-based material. Scanning electron microscopy (SEM) and focused ion beam (FIB) have been used to determine the morphological changes on the surface as well as within the hemp shiv. It was found that the sol–gel coatings caused a reduction in water uptake but did not strongly influence the moisture sorption behaviour of hemp shiv. Fourier transformed infrared (FTIR) spectroscopy shows that the coating layer on hemp shiv acts a shield, thereby lowering peak intensity in the wavelength range 1200–1800 cm−1. The sol–gel coating affected pore size distribution and cumulative pore volume of the shiv resulting in tailored porosity. The overall porosity of shiv decreased with a refinement in diameter of the larger pores. Thermal analysis was performed using TGA and stability of coated and uncoated hemp shiv have been evaluated. Hemp shiv modified with sol–gel coating can potentially develop sustainable heat insulating composites with better hygrothermal properties

A Sol-Gel Process for the Preparation of Micro-Spheroids of Nickel (II) Hydroxide

The sol-gel procedure for the preparation of nickel(!!) hydroxide micro-spheroids of definite size and shape is described. The process is a two-stage operation. In the first stage the concentrated sol of Ni(OHh is produced by a sequence of precipitation, centrifugation, resuspension and electrodialysis. In the second stage the sol is transformed into a gel in a column in the counter-current flow of a dehydrating alcohol. Flow rate control of the sol and of the dehydrating agent allow preparation of spherical particles of different diameters in the range of 0.1 to 0.3 mm

Advancement of Sol-Gel–Prepared TiO2 Photocatalyst

This chapter elaborates a review of sol-gel–prepared TiO2 photocatalyst for different photocatalytic applications. Among the semiconductors employed, TiO2 is known as an attractive photocatalyst owing to its high photosensitivity, nontoxicity, easy availability, strong oxidizing power and long-term stability. Some research works related to the effect of sol-gel preparation parameters on physicochemical properties and different photocatalytic applications of prepared TiO2 photocatalysts are reported. Furthermore, various sol-gel and related systems for modification of TiO2 photocatalytic performance, including transition metals and co-doing of TiO2, were considered. The results illustrated that doping TiO2 with metal ions through sol-gel method usually resulted in an improved efficiency of TiO2 photocatalyst. This method has all the advantages over other preparation techniques in terms of purity, homogeneity, felicity and flexibility in introducing dopants in a large concentration, stoichiometry control, ease of processing and composition control