Showing 20 results for Ceramic
Volume 7, Issue 4 (12-2018)
Abstract
The use of environmentally friendly methods is one of the new approaches in combating pathogens in aquaculture systems. The purpose of this research was the possibility evaluation of indirect use of Ag-NPs-coated porous ceramic in water filtration of culture system of shrimp post-larvae to control Vibrio harveyi. In this study, Ag-NPs-coated filters were characterized by various analytical techniques such as FTIR, XRD, ICP, and SEM. In this study, the antibacterial activity of Ag-NPs-coated on porous ceramic against mentioned bacteria via in vitro experiments Zone of inhibition test and Test tub test were determined. Then porous ceramic filter media used for water treatment. Therefore, the performance of the Ag-NPs-coated on porous ceramics in removing pathogenic bacteria was studied in two phases: In the first phase, V. harveyi was inoculated to the water and efficacy of filters of inhibition of bacteria was evaluated via total count of bacteria in the test water; in the second phase, the performance of the Ag-NPs-coated on porous ceramic was tested in the presence of shrimp larvae and efficacy of filters in inhibition of bacteria was evaluated via total count of bacteria, mortality rate, clinical signs, and also hepatopancreas and muscle culture. Based on the results, the highest zone of inhibition obtained in presence of Ag-NPs-coated porous ceramic modified by an aminosilane coupling agent, 3-Amino-Propyl-Triethoxysilane (APTES; the samples were immersed in the silver colloidal solution for 24h). The results of the flow test showed the highest bacteria removal efficiency from water with complete removal of the targeted pathogen. In the second phase, the results indicated a significant difference in decreasing of water bacteria, shrimp mortality and disease symptoms in treatment containing silver compounds compare to controls. According to results, Ag-NPs-coated porous ceramic have a high bacteria removal efficiency for the disinfection of water of culture system of shrimp to control Vibrio harveyi.
Volume 10, Issue 4 (10-2008)
Abstract
The conditions for the refinement of clarified sugarcane juice, including temperature (50o, 60o and 70oC) and pressure (0, 0.5, 1 and 1.5 bars) by micro-filtration membrane technology were investigated. The raw sugarcane juice was initially pre-filtrated with lime and then the juice obtained (clarified juice) processed using a ceramic micro-filter mem-brane (0.2 micrometer). The characteristics investigated included brix, polarity (sucrose percent), turbidity, color and purity. The results showed that the effects of different proc-ess conditions with micro-filtration on reduction of turbidity and color were significant at probably <0.01 and probably <0.05, respectively. For other characteristics, no significant difference was observed. Finally, a temperature of 70oC and transmembrane pressure of 1.5 bar were determined as the optimum conditions for ceramic micro-filtration. Mem-brane processing at 70oC and 1.5 bars reduced the turbidity, viscosity and color of clari-fied juice 56.25%, 16.67% and 6.49%, respectively, and increased 0.87 units of purity.
Volume 12, Issue 2 (2-2021)
Abstract
Abstract
The decoration of potteries was very important in prehistoric and before protoliterate periods. The structure and motives on the ceramics accommodate the possibility of the study about ancient human thoughts and demonstrate the dependence of his ideas and minds on the natural and social environments in which he has lived and grew up. Therefore, by examining these motives, one can study and analyze the mental, ideological, social and economic complexities of ancient societies. The authors have studied the organization of pottery production in an ancient society by researching the "grammar" of motives and aesthetic quality of prehistoric painted pottery. The culture of Tall-e-Bakun A which has prevailed in Marvdasht plain in Fars Province at the end of 5th and the beginning of 4th millennium BCE, is the case study of this investigation.
The ceramics have been produced in a standardized productive organization and a specialized process during Bakun A phase. Requirements and rules have been used in creating patterns on pottery of this period, the most important of which are: placing motifs in frames, symmetry, repetition, reversing and clockwise direction of motifs, creating motifs with negative technique and using separating elements. This study also has proved that the relationship between the designs and the forms of the potteries has been relative. The grammar and method of motives on jars, cups and bowls have shown that often the same patterns and models are used in their execution. The execution of them.
Volume 12, Issue 4 (12-2021)
Abstract
Today, using fungi as source of bioactive compounds such as proteins for biosynthesis of different types of nanoparticles is being developed. In this study the characteristics of the biosynthesized zirconia nanoparticles (ZrO2 NPs) using Saccharomyces cerevisiae and Colletotrichum gloeosporioides were compared. Extracellular biosynthesis of ZrO2 NPs was carried out by adding 1 mM of K2ZrF6 to S. cerevisiae and C. gloeosporioides culture medium separately. Nanoparticle biosynthesis was confirmed by visual observation of color and transparency changes in the culture medium, UV-Vis spectrophotometry and XRD. FTIR results demonstrated the effects of some possible secretory compounds of the fungi such as protein, phenol and alcohol in the biosynthesis and stability process of the biosynthesized ZrO2 NPs. The results of elemental analysis (EDAX) confirmed the biosynthesis of zirconia nanoparticles as well as the presence of some elements in organic compounds participating in the biosynthetic process. The effect of time on the biosynthesis of the nanoparticles was also investigated. The color and transparency changes of the culture media, peak formation at less than 300 nm in spectrophotometry confirmed the extracellular biosynthesis of ZrO2 NPs and also XRD results confirmed the crystalline nature of the biosynthesized ZrO2 NPs based on their crystallite size. The FESEM results showed that the most of the nanoparticles were amorphous and some were monoclinic in shape with sizes (19.49 and 35.60 nm) for C. gloeosporioides and (45.81 and 74.07 nm) for S. cerevisiae. The monoclinic structure of the biosynthesized nanoparticles was confirmed by UV, FTIR and XRD results.
Volume 14, Issue 2 (5-2014)
Abstract
Syntactic foams are a kind of composite; consist of polymeric matrix and hollow micro-balloons. They have high strength to weight ratio if it compare to the neat matrix material. In this paper epoxy resin as matrix and ceramic micro-balloons are used and 36 kinds of syntactic foam were fabricated to investigate the effect of preparation factors such as: mixing speed, mixing time, mixing sequence and extracting bubbles by a vacuum oven on the mechanical properties. Also, two undesirable events like micro-balloon flotation in matrix and porosity are investigated as they affect the foam`s strength. The results show that the speed and sequence of mixing are not effective seriously. However the time needed for mixing would be changed for different volume percent of micro-balloons. It should be noted that as flotation and porosity increases the compression strength decreases. Using the vacuum pressure before molding may decrease the matrix porosity for above 40% micro-balloon volume fraction syntactic foams. Converse to previous, using the vacuum pressure for below 40% micro-balloon volume fraction syntactic foams would increase the floatation and decreases the compression strength.
Volume 14, Issue 4 (3-2011)
Abstract
In today’s markets, production systems must satisfy simultaneously
productivity, quality, and cost requirements. In these systems managers should
focus on managing the flow of production through all the steps that add value to
the final product. Lean production as an efficient approach has been presented in
the literature of production management for increasing the level of products'
quality and decreasing the cost of production. Although this approach is
introduced and studied in many of works, but there are still some challenges in
applying it. It means that there is not a comprehensive model for assessing and
analyzing the lean production in manufacturing firms. This paper tries to present
a model that is able to accurately analyze and measure the leanness degree of
firms.
At first step a hierarchical model for measuring the degree of leanness
has been designed. The proposed model applied at the Yazd Tile and
Ceramic Industries and the degree of leanness of these industries was
measured. Finally, some suggestions for improving the degree of leanness in
these industries have been presented.
Volume 14, Issue 4 (7-2014)
Abstract
Epoxy / ceramic micro balloon syntactic foams are used in marine and automobile industries because of their high specific strength and capability of absorbing energy. In this paper, the neat epoxy and 9 series of syntactic foams with 3 kinds of ceramic micro balloon with different diameters and crush strength in different volume fractions (20%, 40% & 60%) were fabricated. Effect of varying these parameters on the mechanical properties of syntactic foams is investigated. Besides of all, the effect of different loading rate is investigated, too. All of the samples were tested in 10-1, 10-2 and 10-3 strain rates. The results indicate that with increasing the strain rate from quasi-static to moderate rates, the strength of foams became more. Also the results show that the syntactic foam with bigger micro balloon was weak in compression. In syntactic foams of low volume fraction the size effects is more. On the other hand, with increasing the volume fraction, the crush strength of micro balloon is become effective. Plateau stress and absorbed energy results show these facts obviously. With increasing the strain rate, the strength is increased considerably.
Volume 14, Issue 14 (3-2015)
Abstract
In this paper, the behavior of multi-layered ceramic armor and ceramic armor with ductile backing against armor piercing APM2 projectile has been considered numerically. Multi-layered armors in accordance with BR7 ballistic protection class should protect against AP 7.62-mm projectiles with impact velocity of 830m/s. Results show that unlike high strength steel, ceramic resists against initial penetration of brass jacket and lead filler and erodes them at initial stages. This enables higher resistance in ceramic armor with similar mass in comparison with the steel one. It is illustrated that ceramic armor with ductile backing beside above characteristics has the capability of bullet jacket strip and capturing brass jacket while the core penetrates through the armor. This characteristic is not observed in multi-layered ceramic armor without the backing plate. Ceramic armor with backing plate reduces projectile's exit velocity one ninth the residual velocity of multi-layered ceramic armor and one nineteenth the residual velocity of high strength steel armor with similar mass. Another point discussed in this paper is the effective ceramic mass resisting against the projectile. The more mass involved, the more ballistic resistance gained.
Volume 15, Issue 1 (3-2015)
Abstract
In this paper, the behavior of multi-layered Alumina ceramic armor against high velocity projectile has been considered. Due to the conoid failure mechanism of ceramics under impact loadings, high compressive strength and erosive behavior of them against projectiles, specially ogive nosed ones, various incorporation of this material in modern armor applications is possible. Consideration of this behavior by means of different constitutive relations in detail, such as given by Johnson & Holmquist, one can design an armor with higher ballistic performance. In this study, "conoid fracture" behavior of "ceramic - elastomer" armor has been simulated in LS - Dyna with Johnson - Holmquist constitutive relation. As a result, the conoid failure of top layer ceramic causes the impact pressure to decrease in back layer, and consequently the epoxy interface transfers the pressure distribution between ceramic layers, causing growth and propagation of conoid failure thus distributing the pressure in larger area, finally resisting against projectile penetration in the armor. Application of this armor system for light-weight and heavy back layer-free purposes, would be of the highest priority against high velocity projectiles.
Volume 15, Issue 9 (11-2015)
Abstract
Due to high hardness, low density and heat resistance, ceramics are widely used in armor applications and industry, thus, in this study, perforation process of projectile into ceramic targets is investigated analytically and numerically and a modified model is developed. In the analytical section, Woodward’s theory, one of the important theories in perforation process of projectile into ceramic targets, is investigated and some modifications are applied in Woodward’s model, hence the ballistic results of analytical method are improved and the modified model shows good agreement with the experimental results that in the analytical section, the modified model is based on Woodward’s model and modification of semi-angle of ceramic fracture cone, erosion, mushrooming and rigid from of projectile and also changes in yield strength of ceramic during perforation process, damage, are considered. In the numerical section, a finite element model is created using Ls-Dyna software and perforation process of projectile into Ceramic-Aluminum target is simulated. The results of the analytical method and numerical simulation are compared to the results of the other investigators and results of modified model show improvement in prediction of ballistic results.
Volume 16, Issue 10 (1-2017)
Abstract
In this paper, an analytical model has been developed for modeling high velocity impact on ceramic/nanocomposite targets. In this model, penetration resistance of ceramic is determined based on cavity expansion analysis and variables during perforation of projectile onto ceramic are considered. Also the force of ceramic-composite interface is modified. Ballistic performance of the ceramic/composite target is investigated with adding and dispersing of nano particles of zirconia (ZrO2) in the matrix of back up composite. Ballistic impact tests were performed to validate the analytical predictions. These tests were performed by firing 10 mm steel flat ended projectile onto ceramic/composite target. Front layer is alumina ceramic and composite laminates of back up made of E-glass/epoxy with and without nano-zirconia particle of 5 wt%. The effect of nano-zirconia dispersion in the matrix for different failure modes is discussed. Experimental results revealed an improvement in the ballistic performance of samples with nano-zirconia particle. The analytical predictions of ballistic limit velocity and residual velocity of projectile are found to be in good agreement with the experimental results.
Volume 18, Issue 1 (3-2018)
Abstract
Among the pieces are ceramic balls that are special because of the physical and mechanical properties that have been the industry's attention. Ceramic balls are produced by powder metallurgy way. Finally, by grinding, lapping and polishing processes is reached to surface smoothness, roundness and diameter of the desired. Since the required finishing process to ceramic finishing for surface quality and geometry accuracy of the desired is Time consuming and expensive, creating an economical finishing way is an important issue in the application of ceramic balls. In this article, a mechanism for ceramic balls lapping is proposed. Proposed mechanism consist of two lap plates. Lower lap plate has an eccentric v-shaped groove and placed on out of upper lap plate rotation center. Kinematic analysis of proposed mechanism has been done and lapping trajectory has been investigated on the ball surface. The results of kinematic analysis and lapping trajectory show that the proposed mechanism increases removal rate and roundness of the ball. In general, efficiency and productivity of balls lapping process will improve to achieve the desired surface smoothness and roundness. It can increase the speed of operation and reduce the process time by increasing removal rate.
Volume 18, Issue 1 (3-2018)
Abstract
Ceramic matrix composites (CMCs) are a new class of high technology materials which can be utilized as a replacement for metallic super-alloys. CMCs have a vast array of applications in modern industries due to their upstanding properties, including low density, relatively high hardness and fracture toughness, and high corrosion and wear resistance. Extremely high hardness and inhomogeneous structure of CMCs cause unstable process and high grinding forces and temperature. This research was conducted in order to overcome the grinding challenges of these composites by recognizing and analyzing the effects of main process parameters comprising cutting speed, feed speed, and depth of cut on the grinding forces, specific energy, and grinding force ratio in three different environments including dry, wet and MQL grinding. To evaluate the significance of input parameters and their influence on the responses and also to derive predicting equations, Analysis of Variance (ANOVA) was employed. It was concluded that MQL technique is the most efficient cooling-lubrication method where implementation of this process reduces the tangential grinding force by 38.88% and normal grinding force by 31.16%, relative to dry grinding; however, the amount of force reduction in wet grinding is 34.22% for tangential grinding force and 24.81% for normal grinding force, relative to dry grinding. In addition, increase of cutting speed leads to reduced grinding forces and force ratio and higher amounts of specific energy, and also increase of feed speed and depth of cut cause higher grinding forces and force ratio and lower amounts of specific energy.
Volume 18, Issue 2 (4-2018)
Abstract
Advanced ceramics are a group of materials that have been used in many industries due to their properties such as high temperature stability, high strength, high abrasion resistance and high corrosion resistance. Grinding process is one of the most important and most commonly used techniques for machining and polishing of ceramics. However, poor grindability, high surface defects in the workpiece due to the brittleness of ceramics and the high grinding forces, high wear rate of diamond wheel (tool), high costs due to the use of cutting fluid, low cutting productivity (low production rate), are of the problems of ceramics grinding. The minimum quantity lubrication (MQL) new technique is one of the methods recently introduced in machining processes aimed at improving lubrication performance of cutting fluids, reducing fluid consumption and promoting the use of low-hazard and environmentally friendly fluids. In this study, the minimum quantity lubrication technique was used in the grinding process of zirconia ceramic in order to investigate its effects on the grindability of ceramics. Also, since the type of lubricant and grinding wheel can affect the performance of minimum quantity lubrication in this process, the type of lubricant and diamond wheel were used as variables in the experiments. The grinding forces, surface roughness and surface texture of the grinded samples have been evaluated. The results show that under the minimum quantity lubrication conditions, applying the appropriate type of lubricant and grinding wheel can significantly affect the grindability of zirconia ceramic.
Volume 19, Issue 5 (5-2019)
Abstract
Penetration into ceramic-aluminum targets is of prime importance for researchers in defense and non-defense industries. In this study, the effect of a blunt projectile having a specified speed and penetrating into a ceramic-aluminum target at angles of 0, 15, 30, and 45 degrees is investigated. In this research, 8 experiments were carried out at Ballistic Laboratory of Imam Hossein University and the design of the experiments was carried out in such a way that the facilities of the laboratory could be used. The results of the study showed that by increasing the angle of obliquity, is decreased substantially in ceramic-aluminum target, and when the angle of obliquity is increased beyond a certain limit, will ricochet. Also, in this study, numerical investigation was performed, using Autodyne software. In this numerical simulation, the impact of the blunt projectile at 700 m/s on ceramic-aluminum target was carried out to determine the penetration depth into the given target. The blunt projectile penetration was simulated with oblique carbide plates supplemented with aluminum 2024-T3 and the residual velocity and mass values of the projectile were determined at the exit of the combined target. The projectile was assumed to be rigid and the Johnson–Holmquist structural model was used to describe ceramic behavior and Johnson-Cook material model was used for projectile and target. The results of the experiments and numerical simulation were compared and there was a good agreement between these two modes of investigations, indicating the validity and accuracy of simulation assumptions.
Volume 20, Issue 6 (6-2020)
Abstract
Ceramic Matrix Composites (CMCs) are designed to overcome the main drawbacks of monolithic ceramics, especially their brittleness, in high-performance and safety-critical applications. Owing to the inherent properties of CMCs, especially heterogeneous structure, anisotropic thermal and mechanical behavior, and the hard nature of fibers or matrix, the machining process becomes extremely challenging as the generated surface suffers from undesirable quality. Taking the high hardness of ceramic matrix into account, grinding with diamond abrasives is the only efficient way for machining of CMC materials. The aim of this paper was to study the influence of grinding parameters (cutting speed, feed speed, and depth of cut) and different cooling-lubrication conditions (i.e. dry, fluid, and minimum quantity lubrication) on surface roughness, process efficiency, and tool wear. The results indicated that MQL leads to the best results in terms of surface quality and process performance. Furthermore, increasing of cutting speed and feed speed decreased and increased surface roughness, respectively, while depth of cut had an insignificant effect on the roughness value. Regarding the experimental results, four machining strategies considering quality, productivity, and efficiency criteria were developed. Eventually, the material removal mechanism was evaluated using SEM photos, indicating that brittle fracture is the dominant removal behavior of CMC materials.
Volume 20, Issue 9 (9-2020)
Abstract
In impact mechanics, layered targets are important due to their high resistance to projectiles penetration. This paper deals with the analytical and numerical analysis of the penetration of tantalum projectiles on semi-infinite ceramic-metal layered targets. In the analytical study, a new modified analytical model based on the analytical model of Fellows is presented. The modifications made to the Fellows analytical model include the changes of velocity of the projectile and ceramic, the angle and timing of the formation of the ceramic cone, the erosion of ceramic, projectile and backing. Each of these modifications alone reduces or increases the depth of penetration, and all of these modifications together improve the depth of penetration. Numerical analysis is done using Abaqus software. The behavior of projectile, ceramic, and aluminum is modeled on the actual behavior of the materials and the deformation. The projectile and backing behavior is modeled with the Johnson-Cook equations and the ceramic behavior with the Drucker-Prager plasticity equation and the state equation of Mie-Gruneisen. The results of the new correction analytical model and numerical simulation are compared with the results of other authors and experimental data. The results show very good agreement. The new modified analytical model, by removing the Fellows model defects, provides a more accurate prediction of the depth of projectile penetration in the ceramic-metal layered targets. So, the weakness of this model, which is related to the unpredictability of penetration depth at low speeds, has been remedied.
Volume 22, Issue 10 (10-2022)
Abstract
With the development of additive manufacturing technology, the quantity of devices that can be used in small office with the commercial or educational purposes increases. In this research, the goal is to build a desktop 3D printer with selective laser sintering technology, which can be used for research purposes. The main concentration is focused on fabrication with parts that can be manufactured in the country or can be procured from the domestic market. It is also tried to make the 3D printer compatible with the common open-source additive manufacturing softwares. The fabricated 3D printer has the ability to work with all kinds of common polymer powders. In addition, it is easy to update the device's firmware according to the researcher's needs. The capabilities of the device was tested with Glucose powder, paraffin wax powder, and thermoplastic-ceramic material combinations. It is currently used for research on fabricating ceramic parts with indirect laser sintering.
Volume 23, Issue 11 (11-2023)
Abstract
Ceramic materials are desirable in structural applications because of their strength at high temperatures, low thermal expansion, and excellent wear resistance. However, ceramic structures are generally brittle and will fail due to inherent flaws that can be introduced into the material through processing, handling, or while in service. In the strength test samples of ceramic materials, the observed strength depends on the sample volume and the test method, and the results have significant scattering. On the other hand, it is important to recognize the variability of the strength of ceramic materials for structural design, and in the design process, this variability usually requires a probability-based failure criterion, which, due to the brittle fracture of ceramics, usually uses the Weibull distribution to represent their strength. With the help of Weibull distribution, the concept of effective volume is defined and by using it, the strength of a test sample with a specific geometry and loading is predicted from another sample that has a different geometry and loading. In this research, the effective volume for a truncated cone under internal pressure has been derived analytically. With the effective volume for this configuration and a sufficient number of flexural strength tests with the help of small and low-cost flexural specimens, it is possible to predict the tensile strength of the ceramic truncated cone without conducting expensive tests. for a problem with a specific material property and dimensions, the effective volume was calculated numerically and it had a 3% error compared to the analytical value.
Iran Fatemeh Abdorrahimain, Iran Mahmood Heydarian, Iran Mohammadamin Emami,
Volume 30, Issue 1 (1-2023)
Abstract
The petrographic analysis of ceramics can often answer a wide variety of archaeological questions, especially regarding fabrication, manufacturing processes which were despite focused on the construction and trade of pottery. However, ceramics which were collected from the same site can mostly differ in their chemistry as well as fabrics. As is applied in many cases, essential archaeological survey and documentations in a theoretical framework are key to the proper application of ceramic petrography through the archaeometrical research. This paper deals with the petrographically approach on Kura-Araxes or Early Bronze Age ceramics manufacturing processes of Sonqor Plain. It is of worth-knowing to contribute that the contact and exchange strategies between indigenous communities and several cultural-spheres during Early Bronze Age (beginning of the fourth millennium BC) in this area. Morphological data along with mineralogical composition of ceramics were applied to determine the major elements of the pottery sherds. Based on the result, one can be suggested that all of sherds are in the same group and were demonstrated mightily local productions. The ceramic manufacturing technology indicates same patterns of material interactions during the ETC or Kura-Araxes in all of the investigated sites in Sonqor Plain.
