scholarly journals Electroosmotic pressure in the process of a biocompatible coating applying on the inner surfaces of nanostructured ceramics

2019 ◽  
Keyword(s):  
Base Material ◽  
Ceramic Materials ◽  
Porous System ◽  
Chemical Additives ◽  
Biocompatible Coating ◽  
Internal Surfaces ◽  
Electrochemical Application ◽  
Average Size ◽  
Nanostructured Ceramics

The role of the effect of electroosmosis in the process of electrochemical deposition of a biocompatible coating on the inner surfaces of porous nanostructured ceramics, a material used to make endoprostheses and implants in medicine, is discussed. The biocompatibility of endoprostheses and implants with the human body is ensured by applying a special coating on the internal and external surfaces of the base material. The commonly acepted chemical compound used to form this coating is hydroxyapatite Ca10(PO4)6(OH)2. Multicomponent ceramic materials, from which the basis of endoprostheses and implants are made, are usually obtained by the traditional method of powder metallurgy - sintering, i.e., exposure of a mixture of powders at an elevated temperature under pressure. The material obtained in this way is a polycrystal. In addition, the structure of such a material contains a certain amount of voids in the form of individual pores or their associations (capillaries). The paper shows that the use of nano-structured ceramic materials with a characteristic average size of structural elements (grains, pores and their aggregations) of the order ≈(10–9–10–7)м as a material for the manufacture of implants may determine the greater efficiency of the process of electrochemical application of a biocompatible coating on them, since the resulting large electroosmotic pressure in the capillaries leads to a greater degree of filling of the porous system with electrolyte. The magnitude of the electroosmotic pressure can be increased by increasing the strength of the acting electric field or by decreasing the dielectric constant of the electrolyte ε when additional chemical additives are introduced into the electrolyte. The maximum degree of hollow channels (capillaries) filling with electrolyte, and, consequently, the efficiency of applying a biocompatible coating to the internal surfaces of ceramics using the electrochemical method, is achieved with the capillary system of the material being completely open.

scholarly journals Green Nanocoatings Based on the Deposition of Zirconium Oxide: The Role of the Substrate

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1043
Author(s):  
Vitor Bonamigo Moreira ◽  
Anna Puiggalí-Jou ◽  
Emilio Jiménez-Piqué ◽  
Carlos Alemán ◽  
Alvaro Meneguzzi ◽  
...  
Keyword(s):  
Zirconium Oxide ◽  
Active Sites ◽  
Modified Electrodes ◽  
Chemical Conversion ◽  
Ceramic Materials ◽  
Point Of View ◽  
Oxide Coatings ◽  
Alloying Element ◽  
Substrate Nature

Herein, the influence of the substrate in the formation of zirconium oxide monolayer, from an aqueous hexafluorozirconic acid solution, by chemical conversion and by electro-assisted deposition, has been approached. The nanoscale dimensions of the ZrO2 film is affected by the substrate nature and roughness. This study evidenced that the mechanism of Zr-EAD is dependent on the potential applied and on the substrate composition, whereas conversion coating is uniquely dependent on the adsorption reaction time. The zirconium oxide based nanofilms were more homogenous in AA2024 substrates if compared to pure Al grade (AA1100). It was justified by the high content of Cu alloying element present in the grain boundaries of the latter. Such intermetallic active sites favor the obtaining of ZrO2 films, as demonstrated by XPS and AFM results. From a mechanistic point of view, the electrochemical reactions take place simultaneously with the conventional chemical conversion process driven by ions diffusion. Such findings will bring new perspectives for the generation of controlled oxide coatings in modified electrodes used, as for example, in the construction of battery cells; in automotive and in aerospace industries, to replace micrometric layers of zinc phosphate by light-weight zirconium oxide nanometric ones. This study is particularly addressed for the reduction of industrial waste by applying green bath solutions without the need of auxiliary compounds and using lightweight ceramic materials.

scholarly journals Role of Sintering Temperature in Production of Nepheline Ceramics-Based Geopolymer with Addition of Ultra-High Molecular Weight Polyethylene

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1077
Author(s):  
Romisuhani Ahmad ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Wan Mastura Wan Ibrahim ◽  
Kamarudin Hussin ◽  
Fakhryna Hannanee Ahmad Zaidi ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Sintering Temperature ◽  
Ceramic Materials ◽  
Microstructural Properties ◽  
Sintering Process ◽  
Final Microstructure ◽  
Change Of Microstructure ◽  
Ultra High Molecular Weight

The primary motivation of developing ceramic materials using geopolymer method is to minimize the reliance on high sintering temperatures. The ultra-high molecular weight polyethylene (UHMWPE) was added as binder and reinforces the nepheline ceramics based geopolymer. The samples were sintered at 900 °C, 1000 °C, 1100 °C, and 1200 °C to elucidate the influence of sintering on the physical and microstructural properties. The results indicated that a maximum flexural strength of 92 MPa is attainable once the samples are used to be sintered at 1200 °C. It was also determined that the density, porosity, volumetric shrinkage, and water absorption of the samples also affected by the sintering due to the change of microstructure and crystallinity. The IR spectra reveal that the band at around 1400 cm−1 becomes weak, indicating that sodium carbonate decomposed and began to react with the silica and alumina released from gels to form nepheline phases. The sintering process influence in the development of the final microstructure thus improving the properties of the ceramic materials.

CERAMICS BASED ON ORGANOSILICON POLYMERS-PRECURSORS: MICROSTRUCTURE AND PROPERTIES (review). Part 2

2021 ◽  
pp. 22-32
Author(s):  
A.M. Shestakov ◽  
Keyword(s):  
Electron Microscopy ◽  
Nmr Spectroscopy ◽  
Material Properties ◽  
Structural Organization ◽  
Ceramic Materials ◽  
Special Role ◽  
Correct Interpretation ◽  
Instrumental Methods ◽  
Organosilicon Polymers

Shows the scientific approaches of various authors to the study of the microstructure of ceramics, the purpose of which is to elucidate its structural organization at the micro- and nanoscale, as well as the influence of the microstructure on the complex of material properties. Various instrumental methods for studying ceramics (NMR spectroscopy, electron microscopy, х-ray structural analysis, etc.) are considered, the permissible capabilities of research methods and analysis of the results obtained with their correct interpretation are shown. The special role of theoretical modeling in understanding the structure of the considered ceramic materials is noted.

The Role of Sodium as a Surfactant and Suppressor of Non-Radiative Recombination at Internal Surfaces in Cu2ZnSnS4

2014 ◽  
Vol 5 (2) ◽  
pp. 1400849 ◽  
Author(s):  
Talia Gershon ◽  
Byungha Shin ◽  
Nestor Bojarczuk ◽  
Marinus Hopstaken ◽  
David B. Mitzi ◽  
...  
Keyword(s):  
Radiative Recombination ◽  
Internal Surfaces

Microhardness and Microstructural Studies on Underwater Friction Stir Welding of 5052 Aluminum Alloy

2017 ◽  
Author(s):  
Srinivasa Rao Pedapati ◽  
Dhanis Paramaguru ◽  
Mokhtar Awang
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Plate Thickness ◽  
Base Material ◽  
Friction Stir ◽  
Underwater Friction Stir Welding ◽  
Void Area ◽  
Average Size ◽  
Microstructural Studies

As compared to normal Friction Stir Welding (FSW) joints, the Underwater Friction Stir Welding (UFSW) has been reported to be obtainable in consideration of enhancement in mechanical properties. A 5052-Aluminum Alloy welded joints using UFSW method with plate thickness of 6 mm were investigated, in turn to interpret the fundamental justification for enhancement in mechanical properties of material through UFSW. Differences in microstructural features and mechanical properties of the joints were examined and discussed in detail. The results indicate that underwater FSW has reported lower hardness value in the HAZ and higher hardness value in the intermediate of stir zone (SZ). The average hardness value of underwater FSW increases about 53% greater than its base material (BM), while 21% greater than the normal FSW. The maximum micro-hardness value was three times greater than its base material (BM), and the mechanical properties of underwater FSW joint is increased compared to the normal FSW joint. Besides, the evaluated void-area fraction division in the SZ of underwater FSW joint was reduced and about one-third of the base material (BM). The approximately estimated average size of the voids in SZ of underwater FSW also was reduced to as low as 0.00073 mm2, when compared to normal FSW and BM with approximately estimated average voids size of 0.0024 mm2 and 0.0039 mm2, simultaneously.

Insight role of TiO2 to improve the photocatalytic performance of WO3 nanostructures for the efficient degradation of ciprofloxacin

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Muhammad Bilal Tahir ◽  
Sohail Farman ◽  
Adil Rasheed ◽  
Hussein Alrobei ◽  
Khurram Shahzad ◽  
...  
Keyword(s):  
Tungsten Trioxide ◽  
Research Work ◽  
Morphological Structure ◽  
Composite Catalyst ◽  
Excitation Wavelength ◽  
Spherical Structure ◽  
Vis Spectroscopy ◽  
Average Size ◽  
Wo3 Nanostructures

Abstract The current research work is to investigate the photocatalytic efficiency and degradation of ciprofloxacin using WO3/TiO2 nanoparticles under visible light irradiation. The nanoparticles of tungsten trioxide (WO3) and its composite with titanium dioxide (TiO2) i.e. WO3/TiO2 was prepared by hydrothermal method. Four basic characterizations were performed to study the prepared sample materials. To study the morphology of the prepared samples, scanning electron microscopy (SEM) was used. The results of SEM clearly showed that tungsten trioxide (WO3) has Rectangular shaped structure. The average size of the pure Tungsten trioxide nanoparticles was about 40–540 nm. The composite of WO3/TiO2 has spherical structure. The reason behind that was the addition of TiO2 in WO3 changes the morphology of pure WO3, and transformed the rectangular structure to a spherical structure. The presence of TiO2 changes the position and orientation of the nanorods in all possible directions. For the detailed analysis of the functional groups present in these samples, band gap, and optical properties of these samples, Fourier transform infrared spectroscopy (FTIR), ultraviolet visible (UV–VIS) spectroscopy and Photoluminescence (PL) emission spectroscopy was used. UV–Vis spectroscopy results showed that the bandgaps of prepared catalysts vary within the range of 2.76 – 2.5 eV. This decrease in bandgap is directly related with the concentration ratio of TiO2 in WO3. The maximum excitation wavelength observed at 440 nm. The maximum degradation efficiency was at 2% of WO3/TiO2 composite catalyst due to unique morphological structure and increase rate of photo absorption.

Microphase-Assisted Reaction Engineering

2001 ◽  
Author(s):  
L. K. Doraiswamy
Keyword(s):  
Fine Particles ◽  
Continuous Phase ◽  
Reaction Engineering ◽  
Solid Particles ◽  
Submicron Particles ◽  
Length Scale ◽  
First Case ◽  
External Agents ◽  
Average Size

A relatively recent concept in organic reaction engineering is the use of submicron particles to enhance the rate of a reaction. These are usually microparticles of solids, but can also be microdroplets of liquids, or even microbubbles of gases. They can be external agents, participating reactants, or precipitating solids. In this chapter, we cover the role of small particles as a whole, which may be regarded as constituting an additional colloid-like phase normally referred to as the microphase. We begin by classifying the microphase in terms of its mode of action and then proceed to an analysis of the following categories of importance in organic technology: microslurry of (1) catalyst or adsorbing particles in a reactive mixture; (2) solid reactant particles in a continuous phase of the second reactant; and (3) solid particles precipitating from reaction between two dissolved reactants, one of which can be a solid dissolving and reacting simultaneously with the other reactant. The microphase in the first case is externally added, whereas that in the last two cases is a reactant or a product. The field is still developing (with many unproven theories), and hence we restrict the treatment to a simple analysis of selected situations based on reasonable assumptions (thus avoiding often unjustified complexity). A microphase can be described as an assemblage of very small dispersed phase particles with average size (dp) much less than the diffusional length scale of the solute. Usually dp < l0μm, compared to the diffusional length scale which is of the order of 50-60 μm. Although the microphase is a distinct phase, the phase in which it is present is commonly regarded as pseudohomogeneous. In a stricter sense, however, it should be regarded as a microheterogeneous phase. Indeed, several studies have been reported on modeling heterogeneous microphase systems (Holstvoogd et al., 1986, 1988; Yagi and Hikita, 1987). In view of the ability of the particles of such a system, pseudohomogeneous or pseudoheterogeneous, to get inside the fluid film, they can enhance the transport rate of the solute through the film. Experimental observations in typical gas-liquid and slurry systems have clearly demonstrated (see Ramachandran and Sharma, 1969; Uchida et al., 1975; Sada et al., 1977a,b, 1980; Alper et al., 1980; Pal et al., 1982; Bruining et al., 1986; Bhaskarwar et al., 1986; Bhagwat et al., 1987; Mehra et al., 1988; Mehra and Sharma, 1988a; Hagenson et al., 1994) the enhancing role of a microphase made up of fine particles. The case of a second liquid phase acting as a microphase or of a solid product performing a similar function has also been studied and found to enhance the reaction rate (Janakiraman and Sharma, 1985; Mehra and Sharma, 1985, 1988b; Anderson et al., 1998). Mehra et al. (1988) and Mehra (1990a,b, 1996) presented a detailed account of the role of different types of microphases in rate enhancement. In all these cases, either a microphase is separately introduced or one of the reactants or products acts as a microphase.

A Study on Ultrasonic Torsional Vibration-Assisted Abrasive Waterjet Polishing of Ceramic Materials

2016 ◽  
Vol 1136 ◽  
pp. 400-405 ◽  
Author(s):  
Yong Wang ◽  
Hong Tao Zhu ◽  
Chuan Zhen Huang ◽  
Jun Wang ◽  
Peng Yao
Keyword(s):  
Torsional Vibration ◽  
Abrasive Particle ◽  
Ceramic Materials ◽  
Abrasive Waterjet ◽  
Critical Depth ◽  
Particle Movement ◽  
Promising Technique ◽  
Abrasive Waterjet Machining ◽  
Waterjet Machining

Abrasive waterjet machining is considered as a promising technique in hard-brittle material polishing. In this paper, The ultrasonic torsional vibration is considered to apply on the workpiece to improve the abrasive waterjet polishing quality and efficiency. The process parameters in the ultrasonic torsional vibration-assisted abrasive waterjet polishing are optimized. The ultrasonic torsional vibration in the role of the abrasive waterjet polishing is investigated. The results show that the application of ultrasonic torsional vibration can effect of abrasive particle movement and increase the critical depth of the ceramic materials.

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