Ceramic Pieces Research Articles

Thermomechanical modelling of ceramic pressing and subsequent sintering

An elastic-visco-plastic thermomechanical model for the simulation of cold forming and subsequent sintering of ceramic powders is introduced and based on micromechanical modelling of the compaction process of granulates. Micromechanics leads to an upper-bound estimate of the compaction curve of a granular material, which compares well with other models and finite element simulations. The parameters of the thermomechanical model are determined on the basis of available data and dilatometer experiments. Finally, after computer implementation, validation of the model is performed against experiments developed on specially designed ceramic pieces, characterized by zones of different density. The mechanical model is found to accurately describe forming and sintering of stoneware ceramics and can therefore be used to analyze and optimize industrial processes involving compaction of powders and subsequent firing of the greens.

Design and Experiment of a High Average Power Ku-Band TE01 Mode Gyro-TWT

A high power Ku -band TE01 mode gyrotron traveling wave tube amplifier (gyro-TWT) is designed and experimented in this paper. The emphasis is put on the gyro-TWT with a high average power. In the design process, a low average velocity spread magnetron injection electron gun and a wideband multichannel TE01 mode input coupler are adopted. At the same time, a high average power curved collector is also applied. To suppress the potential gyro-backward wave oscillator interactions, a new type lossy ceramic rings and lossy ceramic pieces hybrid loaded structure is used in the high-frequency interaction circuit of gyro-TWT. In hot test, the developed Ku -band TE01 mode gyro-TWT is driven by a 70-kV 23-A helical electron beam and produce a ~31.5 kW maximum saturated output average power at 16.2 GHz, corresponding to a saturated peak power of ~450 kW (7% duty ratio), a saturated gain of ~40.5 dB, an efficiency of ~28%. The measured 3-dB bandwidth is ~2.1 GHz. The gyro-TWT is found to be zero-drive stable at these operating points.

Stable carbon and nitrogen isotope ratios of surface food residues in pre-Columbian ceramics from the southern Pacific of Costa Rica as evidence of prehistoric human diets

Introduction: to understand and interpret the consumption of plants and animals by humans in the past requires the investigation of different lines of evidence. Identifiable macroscopic remains of plants and animals, for example seeds and bones, are frequently found at archaeological sites and provide key data on food resources. Their analysis is complemented by the study of pollen grains or phytoliths of cultivated plants within archaeological horizons or in sediment cores recovered from lakes and wetlands near archaeological sites. Another important source of information on human diets in the past consists of food residues preserved in or on artefacts excavated from archaeological sites. Objective: to examine food residues in archaeological pottery from coastal and interior sites in the southern Pacific region of Costa Rica. Methods: we focus on isotopic analysis of carbonized food residues preserved on the inner surfaces of ceramic pots, plates, and other ceramic pieces from archaeological excavations in the intermediate zone (elevations 500-1500m) and coastal zone of the southern Pacific region of Costa Rica. Isotopic analysis of surface food residues on pottery relies on the fact that stable isotopes of carbon (12C and 13C) and nitrogen (14N and 15N) in foods differ based on the photosynthetic pathway of plants and on trophic level. Results: in our analysis of material from twelve sites we found evidence of diets with high amounts of C4 plants (likely maize), legumes, herbivores, and mixtures, but we did not find robust evidence of food residues with isotopic signatures characteristic of reef animals and mollusks, even though some sites are shell mounds. Conclusion: our research represents one of the first studies of surface food residues from Costa Rican pottery, and indicates the potential for studies of this type to strengthen understanding of indigenous subsistence patterns through time and across Costa Rican archaeological regions.

Manufacture of ceramics with high mechanical properties from red mud and granite waste

Red mud (bauxite residue) is an alkaline suspension that is the by-product of alumina production via the Bayer process. Its elevated annual production and the global inventory of red mud determine its valorisation. Granite can be used as a source of fluxing oxides for the ceramic industry, as can the flake-shaped waste generated during the flaming of granite. In this work, a set of ceramic pieces made of red mud and granite waste are prepared and characterised via X-ray diffraction, a hardness test, electron scanning microscopy, a leaching test, and determining open porosity, water absorption, bulk density and flexural strength of the samples. The main crystalline phases in the high-temperature fired products are hematite, pseudobrookite and anorthite; the presence of magnetite reveals their ferrimagnetic character. All samples present high mechanical properties. Leaching results are below critical levels established by regulations.

Pulsed UV Laser Processing of Carbosilane and Silazane Polymers.

Freestanding SiCNO ceramic pieces with sub-mm features were produced by laser crosslinking of carbosilane and silazane polymer precursors followed by pyrolysis in inert atmosphere. Three different pulsed UV laser systems were investigated, and the influence of laser wavelength, operating power and scanning speed were all found to be important. Different photoinitiators were tested for the two lasers operating at 355 nm, while for the 266 nm laser, crosslinking occurred also without photoinitiator. Pre-treatment of glass substrates with fluorinated silanes was found to ease the release of green bodies during solvent development. Polymer crosslinking was observed with all three of the laser systems, as were bubbles, surface charring and in some cases ablation. By focusing the laser beam several millimeters above the surface of the resin, selective polymer crosslinking was observed exclusively.

Influence of Processing Variables on Clay-Based Ceramic Formulations

The properties of ceramic materials and microstructural changes are dependent on the raw materials from which they are made and on the manner in which they are processed, from the composition to the established thermal treatment, heating rate, and firing temperature. In this study, the influence of some processing parameters (formulation, maturation time, and firing temperature) on the physical-mechanical properties and microstructural aspects of ceramic pieces produced from natural aluminosilicates was investigated. Because Brazil does not have many quality ball clays reserves, bentonite was included as a plasticizing agent in this study. The formulations were submitted to maturation for a period of one to four weeks and their characteristics were determined to evaluate plasticity. Following this, the specimens were extruded and subjected to heat at temperatures of 1200, 1300, and 1400oC. The physical-mechanical properties determined were: water absorption, linear retraction, and flexural strength. Statistical analysis was applied. The results showed that, for the analyzed masses, neither the maturation time nor the physical and mechanical properties analyzed had influence on plasticity. The firing temperature was the factor that generated the greatest alteration in results, increasing the mechanical resistance and altering the size and interlocking of the mullite needles.

Design cerâmico e aproveitamento de resíduos sólidos: desenvolvimento de porcelana a partir das cinzas de ossos bovinos

O trabalho apresenta a obtenção de cerâmica tipo porcelana a partir da incorporação de cinza de ossos bovinos, por meio de calcinação e moagem dos mesmos, desenvolvimento de moldes de gesso e testes com óxidos, resultando na vitrificação de peças cerâmicas em referência à culinária maranhense. Como resultado, foram desenvolvidas petisqueiras de porcelana. Diminuindo os descartes de resíduos sólidos descartados na natureza e inserindo posteriormente este conhecimento nas comunidades ceramistas do Maranhão, buscou-se contribuir para o desenvolvimento local utilizando o design.

ELEMENTAL ANALYSIS OF PIGMENTS IN THE CERAMIC HUACO “THROAT-CUTTER WARRIOR WITH TROPHY” USING X-RAY FLUORESCENCE SPECTROSCOPY

The X-ray fluorescence spectroscopy technique was used, with a portable equipment, to analyze traces of elements, in a ceramic piece, commonly called “huaco”, identified as the “Throat-Cutter Warrior with Trophy”, and related to the Moche Culture (between 100 and 800 years a.D.) that developed on Peru´s north coast. The analysis has been made in the coatings of red, brown, orange and white color, in the matrix-paste and in the NIST2711a standard. In the ceramic piece, the presence of Iron was confirmed, in greater quantity, in the overlapped layers of red and brown color, while, in the white pigment, elements of Zinc and Barium were detected, considering that the latter never had been reported in Moche ceramic. In the areas corresponding to the eyes, of metallic aspect, 91% copper has been detected. It is argued that the similitude in iconography and materials would indicate that we are dealing with an ancient piece.

A pilot study on the impact of a pottery workshop on the well-being of people with dementia.

This study seeks to assess the impact of a pottery workshop as a creative arts programme and discover the extent to which people with dementia taking part in an artistic and creative activity engage with it, experience a feeling of well-being, and improve their mood state. In addition, the study will seek to answer the question of whether taking part in a programme of creative activities improves the self-esteem of people with dementia. The research used an uncontrolled, repeated measures design. Thirty users of the National Reference Centre for Alzheimer's and Dementia care in Salamanca (Spain) in a moderate to advanced stage of dementia (Global Deterioration Scale 4, 5, or 6) were divided into five intervention groups that received ten 45-minute sessions in which they were helped by facilitators to make different ceramic pieces. The participants were assessed before and after the intervention with a self-esteem scale, and they rated their mood before and after the sessions on a graphic scale. During the art sessions, two observers recorded the presence of multiple indicators of well-being. The intervention was found to have a significant impact on mood and self-esteem that was independent of the participants' Global Deterioration Scale. Regarding the tool used to observe well-being, the participants scored highly in the domains of sustained attention, pleasure, self-esteem, and normalcy, with low scores in negative affect and sadness. Pottery may be a highly suitable activity for people with dementia, as they may enjoy both the activity and the creative process, with it triggering a positive mood during the sessions, providing psychological well-being and reinforcing their self-esteem.

Foreign Body-Related Extremity Trauma in Children: A Single-Center Experience.

The extremity foreign body in a child has propensity of getting missed or mistaken diagnosis. We report our experience of extremity foreign body trauma in order to increase awareness of this disease entity. The retrospective series of 24 retained foreign bodies was based on a 10-year chart review of emergency data (ICD code Z18). Patients with both upper and lower limb affections were included. Patients with ocular, otolaryngeal, tracheobronchial, gastrointestinal, and axial foreign bodies were excluded from the study. Male predominance (M:F = 20:4), young patient age (mean 6.8 years), variable lag period for consultation (range 3 h–8 years), and majority lower limb affection (58%; foot [7; 29%] and knee [5; 20.8%]) were some characteristics of extremity foreign bodies trauma. The foreign bodies reported were metallic needle (7; 29%), rubber band (3; 12.5%), pellets (3; 12.5%), bangle glass (2; 8%), glass pieces (2; 8%) “dhaga,” wooden twig, wooden thorn, ceramic earthen pot pieces, stapler pin, broomstick, and cracker piece in one case each (1; 4%). Postremoval, the wound healing was uneventful in all patients. Foreign body-related extremity trauma in children is a rare event. It has its own set of characteristics and differential diagnosis. Familiarity with the regional practices and customs is must to establish the circumstances/nature of the foreign body injury. The foreign body should preferably be removed in a well-equipped setting.

Preliminary evaluation of the physical properties of red ceramic incorporated with solid residue

AbstractThe food processing industry highlights the daily generation of large amounts of eggshell solid residue. In this way, this residue becomes a non renewable raw material to be reused as an additive in red ceramics, in order to reduce the volume of disposal to the environment and improve the physical properties of the product. The objective of this work was to evaluate the forming moisture, linear shrinkage of drying and shrinkage of drying burning of ceramic test pieces (CS’s) with formulations with 2% and 3% of white eggshell residue (ER) incorporated in clay. The clay and ER were collected in the city of Pelotas-RS. The ER sample was analyzed by X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD). After pressing, natural and artificial drying was carried out and the CS’s were burned. These were evaluated through normative parameters C-020/95, C-021/95 and C-026/95. The values obtained for the forming moisture were between 5.82 and 8.78%, for the linear shrinkage of drying between 0.10 and 0.43% and, for the linear contraction burning between -0.29 and 0.08%. The results showed that the addition of ER to the ceramic mass helped in the reduction of the forming moisture and the linear shrinkage of the ceramic test pieces.

Ceramic materials from Cuatrovitas archaelogical site (Spain). A mineralogical and chemical study for determining the provenance and the firing temperature

The characterization of ceramic materials from archaeological sites is of great importance to learn about the human traditions and regional History. In this work, 12 pieces of ceramics of the Cuatrovitas Archaelogical Site (Bollullos de la Mitación, Seville, Spain) were studied to approach the provenance of the raw material and the firing temperature. In addition, raw materials, from possible sources areas used for the manufacture of those ceramics, were also studied. Mineralogical characterization by XRD and chemical analyses of major, trace and rare earth elements were performed on both raw and ceramic materials. Thin sections, SEM-EDS analyses and micro-XRF mapping were carried out to complete the mineralogical and chemical characterization. The results show that there are two types of ceramic materials, probably prepared by mixtures of different clays and sandy materials. A feasible source area for those raw materials could be the alluvial of the Guadiamar River. According to the mineralogy of the high-temperature phases found in the ceramic pieces, two firing temperatures can be approached: one at 800–850 °C owing to the presence of calcite, and another at 900–950 °C because of the presence of diopside and gehlenite.

The Technical Treatment for Pottery Body by (Kintsugi) Technique in Japanese Pottery – Analytic Study

The aesthetic and technical expertise help in producing the artistic work and achieving results in aesthetic formulations that reflect the aesthetic and expressive dimensions and the reflective dimensions of the pottery, surpassing its traditions, asserting its active presence in life, cherishing it even when it breaks or get damaged by employing techniques that are originated from the Japanese environment. The research problem is to study how ( Kintsugi) technique and similar techniques are used to create new rebirths of pottery pieces after being exposed to external influences that cause them to break in addition to the presence of Japanese thought as a pressurizing incentive to maintain the permanence of the porcelain and cherishing it. The research is important as a reference to the technology of contemporary pottery, enriching the library, and as a source for the scholars and researchers in the field of Japanese pottery. The aim of the research is to identify how the (Kintsugi) technique was used in facing the stresses exerted on the ceramic pieces and the pressurizing thought that motivates it. The research is concerned with the Japanese porcelain products (which was subjected to stress that cause it to break) and treating it by the (Kintsugi) technique. The results showed how the (kintsugi) technique and the techniques derived from it worked in reconstructing the ceramic pieces and creating new entities to meet the pressure of the (wabi-sabi) philosophy, which accepts things with their defects after being subjected to the constant change of status as a characteristic of existence. It sees beauty in imperfection

Study on Precision Polishing of Alumina Ceramics

The research is mainly to investigate the surface roughness by the mechanical polishing for the processing of alumina ceramic materials. In the experiment, the ceramic test piece was placed between the ceramic work ring and the grinding disc and then grinded firstly with an alumina grinding slurry with a particle size of 10 μm to make the original roughness of the test piece reach Ra value of 1.49 μm. Then the silicon carbide slurry polishing was employed to conduct the experiments by changing the concentration of the polishing, particle size, load, rotation and time to observe the polishing effect of ceramic materials under different parameters. The results showed that the silicon carbide particle size of 2μm, with the polishing time of 50 min, the disc speed of 90 rpm, the concentration of 35%, the original surface roughness of alumina ceramic Ra 1.49μm could be downed to 0.22 μm. The improvement rate could reach 94%. And the greater the specimen load with the better grinding efficiency, the smaller the load caused worse cutting force between alumina and the specimen surface. However, the better the surface roughness when the time kept going. Furthermore, alumina ceramic test piece after precision mechanical polishing by 3D surface roughness profiler and scanning electron microscope (SEM) analysis, the observation found that the wave of the original test piece rugged, after grinding and polishing wave front and grinding scratches had been removed, and a smooth surface was obtained.

TinajAR: An Edutainment Augmented Reality Mirror for the Dissemination and Reinterpretation of Cultural Heritage

The use of augmented reality (AR) in cultural heritage (CH) applications opens a whole set of possibilities, including the virtual transformation of CH elements. This paper presents TinajAR, a mirror-based AR application designed to serve both as an edutainment application in the field of CH and also as an artistic expression. As an edutainment application, TinajAR features a multi-marker video-based AR application designed to show virtual ceramic pieces and explain the pottery process through virtual avatars. As an artistic expression, TinajAR seeks to reinterpret an ancient type of cellar called calado, which was used in the past for storing wine in northern Spain. The reinterpretation consists in giving a different but meaningful use to the space. TinajAR was used by around 1800 people during a ceramics exhibition in La Rioja, Spain and was assessed at the satisfaction level with 56 users by means of a system usability scale, giving very satisfactory results.

Large actuation strain over 0.3% in periodically orthogonal poled BaTiO3 ceramics and multilayer actuators via reversible domain switching

Lead titanate zirconate (PZT) ceramics based piezoelectric actuators always suffer from small output strains (typically 0.1%–0.15%) and have recently been criticized for the toxicity problem of the high-concentration lead. In our recent work (Li et al 2017 J. Appl. Phys. 122 074103), we realized large local actuation strain nearly 0.6% in a periodically orthogonal poled (POP) PZT ceramics via reversible domain switching. In this work, we applied the POP method to barium titanate (BT) ceramics and proposed a specially designed multilayer actuator which can output large uniform strain. The simple tetragonal structure of BT ceramics makes it easier to understand the mechanism of reversible domain switching in POP ceramics and its lead-free characteristic is more promising. Firstly, a POP BT ceramic piece was fabricated and the actuation testing results show that local large actuation strain of 0.36% can be obtained under a field of 2 kV mm−1 at 0.1 Hz. However, the actuation strain is non-uniform along the period direction, varying from 0.22% to 0.36%. Then, to output uniform large strain, a four-layer actuator based on the POP BT ceramics was designed and fabricated in which only the in-plane poled regions of the adjacent layers were bonded. Results show that the output strain turns to be uniform in this way, which is 0.34% under 2 kV mm−1, resulting in a very high large-signal (=Smax/Emax) of 1700 pm V−1. The large actuation strain is very stable and keeps unchanged after 20k cycles of operation. It drops quickly with the increasing frequency and is stabilized at 0.18% above 1.0 Hz. Finally, bipolar field testing was conducted on the POP BT based actuator. Results show that the actuator shows electrostriction-like symmetric bipolar actuation behavior with the repeatable actuation strain of 0.3% under 2 kV mm−1. This work may provide a feasible solution to low frequency, large-strain lead-free piezoelectric actuation.

Allowance removal from green pieces as a method for improvement surface quality of advanced ceramics

Advanced ceramics are usually machined after sintering in order to produce details and/or achieve the dimensional and geometric tolerances specified by project. However, this operation is neither cheap nor easy since it requires diamond tools, machine tools of high stiffness, and very low removal rates, even so, the finished parts might invariably contain critical defects. Machining of compacted ceramic powder before sintering, named green machining, is an alternative. This method does not require cutting fluid, presents great machinability, low energy consumption and few or no introduction of damages in the sintered workpiece. The single-action uniaxial pressing is the most used method for obtaining green ceramic pieces. Nevertheless it produces significant density variations in the outer regions of the piece, mainly located around the top and bottom edges, while the variation inside is smaller. The non-uniformity of density is considered responsible for distortion of the ceramic part during sintering. In this study, the distortion of the sintered workpieces was evaluated after green ceramic workpieces were machined using five different allowance values (1, 2, 3, 4, and 5 mm) in order to progressively remove the greatest density gradients. The distortion analysis was made on the top and bottom regions of the workpiece, where each upper and lower punch. operates, respectively. It was found that the distortion of the top region of the sintered workpieces was reduced about 97% when there was 5 mm of allowance removal and 82% for 1 mm of allowance. In the bottom region, the reduction was about 91% for removal of 5 mm of allowance and 48% for 1 mm. Cutting tool wear, cutting force, and surface roughness of green and sintered workpieces were also analyzed. In general, the influence of tool wear on surface roughness of sintered pieces and the correlation between surface roughness of the sintered pieces and the corresponding green ones were observed.

Azulejos históricos do Cemitério Nossa Senhora da Soledade, Norte do Brasil: caracterização microestrutural, física e mineralógica

Abstract During the nineteenth century, historical glazed tiles were used in the mortuary architecture of Nossa Senhora da Soledade Cemetery, in Belém. These ceramic pieces are an extraordinary part of Brazilian cultural heritage but are at a high deterioration stage due to conditions to which they are subjected. The aim of this research was the microstructural, physical and mineralogical characterization of glazed tiles from Nossa Senhora da Soledade Cemetery. The samples consisted of Portuguese fragments from the nineteenth century, decorated by stamping. The characterization was performed by optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, water absorption test, and X-ray diffractometry. The results indicated that glazed and ceramic layers have manufacturing defects and a heterogeneous character due to the handmade production process. The porosities vary from 13.3% to 22.9%. The ceramics are composed of quartz, gehlenite, calcite, rutile, cristobalite, diopside, anorthite, hematite and wollastonite. According to the results, despite many similarities (country of origin, century of production, decorative technique), the samples have variations in their microstructure and mineralogy. Information regarding the compositions of the tiles and their variation is important to support future restorative interventions.

An L-shaped ultrasonic linear piezoelectric motor with two second-order bending coupling modes

ABSTRACTIn order to simplify the motor structure, reduce the difficulty of modal coupling and obtain a wide driving frequency range, a new piezoelectric motor which works on the two second bending vibration coupling modes was designed in this study. Based on the bonded-type structure, it consists of four pieces of piezoelectric ceramics, a copper substrate and one driving tip. The finite element method (FEM) was used for optimizing the design and further analysis, and a prototype was designed, fabricated and experimentally researched in this study for verifying its mechanical properties. Experimental results show that the working frequency is 89 kHz, and the maximum value of the movement velocity of a certain direction is 53 mm/s, at 680 Vpp(voltage, peak to peak value),while the maximum movement velocity of reverse direction is 44 mm/s at the same voltage.

Abrasive Jet Drilling of Alumina Ceramic with Pressurized-Fluidized Bed Set-up

Nontraditional methods of machining processes cover a wide range of technologies, possessing slower material removal rate with high accuracy and precision which are impractical and costly in traditional machining methods. Abrasive Jet Machining (AJM) is an effective technique that can precisely machine hard, brittle and heat sensitive materials like glass, quartz, sapphire, semiconductor materials, super alloys, mica, refractory materials and ceramics to create slots, thin sections, contouring, drilling, etching, deburring, and polishing. Pressurized and Fluidised Bed Abrasive Jet Machining (PFB-AJM) is one such modern machining process that employs the high speed homogeneous mixture of compressed air and abrasive particles to impinge on the work piece surface with high kinetic energy to remove material by impact erosion. The principle of development of brittle fracture, expansion and propagations of cracks in lateral and longitudinal directions due to repeated impact of the solid abrasive grains on the tough and hard work piece material occurs in AJM, where the total kinetic energy is converted into impact energy. The effective utilization of the resources or selected input process parameters and previous experience of the operators affect the machining processes of different non traditional methods (NTD). Hence the machining parameters are optimized for the economic, efficient and effective utilization of the resources. This paper focuses on experimentation of K-60 alumina ceramic work piece material with silicon carbide (SiC) abrasives on an indigenously fabricated AJM set up basing upon pressurized power feed and fluidized bed mixing chamber system. The impact of three process parameters such as pressure (P), nozzle tip distance (Z) and grain size (G) on the three responses viz. material removal rate (W), surface roughness (Ra), and depth of cut (H) are analyzed. Experiments are carried out according to the Taguchi Orthogonal Array. Then principal component analysis (PCA) is used for optimization of the process parameters to obtain the optimal parameter settings for achieving the optimal responses and finally the results are experimentally verified.