Abstract: The global solved problem is the calculation of the
parameters of ceramic material from a set of destruction tests of
ceramic heads of total hip joint endoprosthesis. The standard way of
calculation of the material parameters consists in carrying out a set of
3 or 4 point bending tests of specimens cut out from parts of the
ceramic material to be analysed. In case of ceramic heads, it is not
possible to cut out specimens of required dimensions because the
heads are too small (if the cut out specimens were smaller than the
normalised ones, the material parameters derived from them would
exhibit higher strength values than those which the given ceramic
material really has). A special destruction device for heads
destruction was designed and the solved local problem is the
modification of this destructive device based on the analysis of
tensile stress in the head for two different values of the depth of the
conical hole in the head. The goal of device modification is a shift of
the location with extreme value of σ1max from the region of head’s
hole bottom to its opening. This modification will increase the
credibility of the obtained material properties of bioceramics, which
will be determined from a set of head destructions using the Weibull
weakest link theory.
Abstract: Three dimensional non-Interlaced carbon fibre
reinforced silicon carbide (3-D-Cf/SiC) composites with pyrocarbon
interphase were fabricated using isothermal chemical vapor
infiltration (ICVI) combined with polymer impregnation pyrolysis
(PIP) process. Polysilazane (PSZ) is used as a preceramic polymer to
obtain silicon carbide matrix. Thermo gravimetric analysis (TGA),
Infrared spectroscopic analysis (IR) and X-ray diffraction (XRD)
analysis were carried out on PSZ pyrolysed at different temperatures
to understand the pyrolysis and obtaining the optimum pyrolysing
condition to yield β-SiC phase. The density of the composites was
1.94 g cm-3 after the 3-D carbon preform was SiC infiltrated for 280 h
with one intermediate polysilazane pre-ceramic PIP process.
Mechanical properties of the composite materials were investigated
under tensile, flexural, shear and impact loading. The values of
tensile strength were 200 MPa at room temperature (RT) and 195
MPa at 500°C in air. The average RT flexural strength was 243 MPa.
The lower flexural strength of these composites is because of the
porosity. The fracture toughness obtained from single edge notched
beam (SENB) technique was 39 MPa.m1/2. The work of fracture
obtained from the load-displacement curve of SENB test was 22.8
kJ.m-2. The composites exhibited excellent impact resistance and the
dynamic fracture toughness of 44.8 kJ.m-2 is achieved as determined
from instrumented Charpy impact test. The shear strength of the
composite was 93 MPa, which is significantly higher compared 2-D
Cf/SiC composites. Microstructure evaluation of fracture surfaces
revealed the signatures of fracture processes and showed good
support for the higher toughness obtained.
Abstract: Strontium hexaferrite (SrFe12O19; Sr-ferrite) is one of
the well-known materials for permanent magnets. In this study, Mtype
strontium ferrite was prepared by following the conventional
ceramic method from steelmaking by-product. Initial materials;
SrCO3 and by-product, were mixed together in the composition of
SrFe12O19 in different Sr/Fe ratios. The mixtures of these raw
materials were dry-milled for 6h. The blended powder was presintered
(i.e. calcination) at 1000°C for different times periods, then
cooled down to room temperature. These pre-sintered samples were
re-milled in a dry atmosphere for 1h and then fired at different
temperatures in atmospheric conditions, and cooled down to room
temperature. The produced magnetic powder has a dense hexagonal
grain shape structure. The calculated energy product values for the
produced samples ranged from 0.3 to 2.4 MGOe.
Abstract: Metal matrix composites (MMCs) have gained a
considerable interest in the last three decades. Conventional powder
metallurgy production route often involves the addition of reinforcing
phases into the metal matrix directly, which leads to poor wetting
behavior between ceramic phase and metal matrix and the
segregation of reinforcements. The commonly used elements for
ceramic phase formation in iron based MMCs are Ti, Nb, Mo, W, V
and C, B. The aim of the present paper is to investigate the effect of
sintering temperature and V-B addition on densification, phase
development, microstructure, and hardness of Fe–V-B composites
(Fe-(5-10) wt. %B – 25 wt. %V alloys) prepared by powder
metallurgy process. Metal powder mixes were pressed uniaxial and
sintered at different temperatures (ranging from 1300 to 1400ºC) for
1h. The microstructure of the (V, B) Fe composites was studied with
the help of high magnification optical microscope and XRD.
Experimental results show that (V, B) Fe composites can be produced
by conventional powder metallurgy route.
Abstract: Microwave dielectric ceramic materials of
(Mg1-xNix)2(Ti0.95Sn0.05)O4 for x = 0.01, 0.03, 0.05, 0.07 and 0.09 were
prepared and sintered at 1250–1400 ºC. The microstructure and
microwave dielectric properties of the ceramic materials were
examined and measured. The observations shows that the content of
Ni2+ ions has little effect on the crystal structure, dielectric constant,
temperature coefficient of resonant frequency (τf) and sintering
temperatures of the ceramics. However, the quality values (Q×f) are
greatly improved due to the addition of Ni2+ ions. The present study
showed that the ceramic material prepared for x = 0.05 and sintered at
1325ºC had the best Q×f value of 392,000 GHz, about 23%
improvement compared with that of Mg2(Ti0.95Sn0.05)O4.
Abstract: Due to their strong mechanical and thermal properties magnesium borates have a wide usage area such as ceramic industry, detergent production, friction reducing additive and grease production. In this study, microwave synthesis of magnesium borates from MgCl2.6H2O (Magnesium chloride hexahydrate), MgO (Magnesium oxide) and H3BO3 (Boric acid) for different reaction times is researched. X-ray Diffraction (XRD) and Fourier Transform Infrared (FT-IR) Spectroscopy are used to find out how the reaction time sways on the products. The superficial properties are investigated with Scanning Electron Microscopy (SEM). According to XRD analysis, the synthesized compounds are 00-041-1407 pdf coded Shabinite (Mg5(BO3)4Cl2(OH)5.4(H2O)) and 01-073-2158 pdf coded Karlite (Mg7(BO3)3(OH,Cl)5).
Abstract: In this paper, the authors try to investigate the
determinants of behavioral intention of the blended E-learning course
for senior students at the Active Ageing University in Taiwan. Due to
lower proficiency in the use of computers and less experience on
learning styles of the blended E-learning course for senior students
will be expected quite different from those for most young students.
After more than five weeks course for two years the questionnaire
survey is executed to collect data for statistical analysis in order to
understand the determinants of the behavioral intention for senior
students. The object of this study is at one of the Active Ageing
University in Taiwan total of 84 senior students in the blended
E-learning for the ceramics teaching course. The research results show
that only the perceived usefulness of the blended E-learning course has
significant positive relationship with the behavioral intention.
Abstract: Stoneware clay, fired clay (as a grog), calcite waste and class C fly ash in various mixing rations were the basic raw materials for the mixture for production of dry pressed ceramic tiles. Mechanical properties (water absorption, bulk density, apparent porosity, flexural strength) as well as mineralogical composition were studied on samples with different source of calcium oxide after firing at 900, 1000, 1100 and 1200°C. It was found that samples with addition of calcite waste contain dmisteinbergit and anorthite. This minerals help to improve the strength of the body and reduce porosity fired at lower temperatures. Class C fly ash has not significantly influence on properties of the fired body as calcite waste.
Abstract: RF magnetron sputtering is used on the ceramic targets, each of which contains zinc oxide (ZnO), zinc oxide doped with aluminum (AZO) and zinc oxide doped with gallium (GZO). The electric conduction mechanism of the AZO and GZO films came mainly from the Al and Ga, the oxygen vacancies, Zn interstitial atoms, and Al and/or Ga interstitial atoms. AZO and GZO films achieved higher conduction than did ZnO film, it being ion vacant and nonstoichiometric. The XRD analysis showed a preferred orientation along the (002) plane for ZnO, AZO, and GZO films.
Abstract: Transient plane source method has been used to
measure the thermal diffusivity and thermal conductivity of a compact
isostatic electroceramics at room temperature. The samples were fired
at temperatures from 100 up to 1320 degrees Celsius in steps of
50. Bulk density and specific heat capacity were also measured with
their corresponding standard uncertainties. The results were compared
with further thermal analysis (dilatometry and thermogravimetry).
Structural processes during firing were discussed.
Abstract: In this work the concentration of steepwater from corn starch industry is monitored using ultrafiltration membrane. The aim was to examine the conditions of ultrafiltration of steepwater by applying the membrane of 2.5nm. The parameters that vary during the course of ultrafiltration, were the transmembrane pressure, flow rate, while the permeate flux and the dry matter content of permeate and retentate were the dependent parameter constantly monitored during the process. Experiments of ultrafiltration are conducted on the samples of steepwater, which were obtained from the starch wet milling plant „Jabuka“ Pancevo. The procedure of ultrafiltration on a single-channel 250mm lenght, with inner diameter of 6.8mm and outer diameter of 10mm membrane were carried on. The membrane is made of a-Al2O3 with TiO2 layer obtained from GEA (Germany). The experiments are carried out at a flow rate ranging from 100 to 200lh-1 and transmembrane pressure of 1-3 bars. During the experiments of steepwater ultrafiltration, the change of permeate flux, dry matter content of permeate and retentate, as well as the absorbance changes of the permeate and retentate were monitored. The experimental results showed that the maximum flux reaches about 40lm-2h-1. For responses obtained after experiments, a polynomial model of the second degree is established to evaluate and quantify the influence of the variables. The quadratic equitation fits with the experimental values, where the coefficient of determination for flux is 0.96. The dry matter content of the retentate is increased for about 6%, while the dry matter content of permeate was reduced for about 35-40%, respectively. During steepwater ultrafiltration in permeate stays 40% less dry matter compared to the feed.
Abstract: The influence of SiC powder addition on densification of Al-SiC compacts during sintering in different atmospheres was investigated. It was performed in a dilatometer in flowing nitrogen, nitrogen/hydrogen (95/5 by volume) and argon. Fine, F500 grade of SiC powder was used. Mixtures containing 10 and 30 vol.% of SiC reinforcement were prepared in a Turbula mixer. Green compacts of about 82% of theoretical density were made of each mixture. For comparison, compacts made of pure aluminum powder were also investigated. It was shown that nitrogen is the best sintering atmosphere because only in this atmosphere did shrinkage take place. Its amount is lowered by ceramic powder addition, i.e. the more SiC the less densification occurs. Additionally, the formation of clusters, enhanced in compacts containing 30 vol.% SiC, is also responsible for limiting the shrinkage. Microstructural examinations of sintered composites revealed that sintering of compacts occurs in the presence of the liquid phase exclusively in nitrogen.
Abstract: This paper deals with the conceptual design of Experimental Helium Cooling Loop (EHCL) for Indian Test Blanket Module (TBM) and its related thermal hydraulic experiments. Indian TBM team is developing Lead Lithium cooled Ceramic Breeder (IN-LLCB) TBM to be tested in ITER. The TBM box structure is cooled by high pressure (8 MPa) and high temperature (300-500C) helium gas.
The first wall of TBM made of complex channel geometry having several parallel channels carrying helium gas for efficient heat extraction. Several mock-ups of these channels need to be tested before finalizing the TBM first wall design and fabrication. Besides the individual testing of such mock-ups of breeding blanket, the testing of Pb-Li to helium heat exchanger, the operational experience of helium loop and understanding of the behavior of high pressure and high temperature system components are very essential for final development of Helium Cooling System for LLCB TBM in ITER. The main requirements and characteristics of the EHCL and its conceptual design are presented in this paper.
Abstract: Construction and Demolition (C&D) wastes contribute the highest percentage of wastes worldwide (75%). Furthermore, ceramic materials contribute the highest percentage of wastes within the C&D wastes (54%). The current option for disposal of ceramic wastes is landfill. This is due to unavailability of standards, avoidance of risk, lack of knowledge and experience in using ceramic wastes in construction. The ability of ceramic wastes to act as a pozzolanic material in the production of cement has been effectively explored. The results proved that temperatures used in the manufacturing of these tiles (about 900⁰C) are sufficient to activate pozzolanic properties of clay. They also showed that, after optimization (11-14% substitution); the cement blend performs better, with no morphological difference between the cement blended with ceramic waste, and that blended with other pozzolanic materials. Sanitary ware and electrical insulator porcelain wastes are some wastes investigated for usage as aggregates in concrete production. When optimized, both produced good results, better than when natural aggregates are used. However, the research on ceramic wastes as partial substitute for fine aggregates or cement has not been overly exploited as the other areas. This review has been concluded with focus on investigating whether ceramic wall tile wastes used as partial substitute for cement and fine aggregates could prove to be beneficial since the two materials are the most high-priced during concrete production.
Abstract: The group of progressive cutting materials can include non-traditional, emerging and less-used materials that can be an efficient use of cutting their lead to a quantum leap in the field of machining. This is essentially a “superhard” materials (STM) based on polycrystalline diamond (PCD) and polycrystalline cubic boron nitride (PCBN) cutting performance ceramics and development is constantly "perfecting" fine coated cemented carbides. The latter cutting materials are broken down by two parameters, toughness and hardness. A variation of alloying elements is always possible to improve only one of each parameter. Reducing the size of the core on the other hand doing achieves "contradictory" properties, namely to increase both hardness and toughness.
Abstract: The purposes of this research is aim to build the energy saving stove for stew coconut sugar. The research started from explores ceramic raw materials in local area, create the appropriate mixture of ceramic raw materials for construction material of stove, and make it by ceramic process. It includes design and build the energy saving stove, experiment the efficiency of energy saving stove as to thermal efficiency, energy saving, performance of time, and energy cost efficiency, transfer the knowledge for community, stove manufacturers, and technicians. The findings must be useful to the coconut sugar enterprises producing, to reduce the cost of production, preserve natural resources, and environments.
Abstract: Superfine pigments that consist of natural and artificial pigments and are made of mineral soil with special characteristics are used in cementitious materials for various purposes. These pigments can decrease the amount of cement needed without loss of performance and strength and also change the monotonous and turbid colours of concrete into various attractive and light colours. In this study, the mechanical strength and resistance against chloride and halogen attacks of cement mortars containing ceramic nano-pigments in an affected environment are studied. This research suggests utilisation of ceramic nano-pigments between 50 and 1000 nm, obtaining full-depth coloured concrete, preventing chlorine penetration in the concrete up to a certain depth, and controlling corrosion in steel rebar with the Potentiostat (EG&G) apparatus.
Abstract: Silicon substrates coated with multiwalled carbon nanotubes (MWCNTs) were experimentally investigated to determine spark breakdown voltages relative to uncoated surfaces, the degree of surface degradation associated with the spark discharge, and techniques to minimize the surface degradation. The results may be applicable to instruments or processes that use MWCNT as a means of increasing local electric field strength and where spark breakdown is a possibility that might affect the devices’ performance or longevity. MWCNTs were shown to reduce the breakdown voltage of a 1mm gap in air by 30-50%. The relative decrease in breakdown voltage was maintained over gap distances of 0.5 to 2mm and gauge pressures of 0 to 4 bar. Degradation of the MWCNT coated surfaces was observed. Several techniques to improve durability were investigated. These included: chromium and gold-palladium coatings, tube annealing, and embedding clusters of MWCNT in a ceramic matrix.
Abstract: This investigation presents the formulation of kerf (width of slit) and optimal control parameter settings of wire electrochemical discharge machining which results minimum possible kerf while machining Al7075/SiCp MMCs. WEDM is proved its efficiency and effectiveness to cut the hard ceramic reinforced MMCs within the permissible budget. Among the distinct performance measures of WEDM process, kerf is an important performance characteristic which determines the dimensional accuracy of the machined component while producing high precision components. The lack of available of the machinability information such advanced MMCs result the more experimentation in the manufacturing industries. Therefore, extensive experimental investigations are essential to provide the database of effect of various control parameters on the kerf while machining such advanced MMCs in WEDM. Literature reviled the significance some of the electrical parameters which are prominent on kerf for machining distinct conventional materials. However, the significance of reinforced particulate size and volume fraction on kerf is highlighted in this work while machining MMCs along with the machining parameters of pulse-on time, pulse-off time and wire tension. Usually, the dimensional tolerances of machined components are decided at the design stage and a machinist pay attention to produce the required dimensional tolerances by setting appropriate machining control variables. However, it is highly difficult to determine the optimal machining settings for such advanced materials on the shop floor. Therefore, in the view of precision of cut, kerf (cutting width) is considered as the measure of performance for the model. It was found from the literature that, the machining conditions of higher fractions of large size SiCp resulting less kerf where as high values of pulse-on time result in a high kerf. A response surface model is used to predict the relative significance of various control variables on kerf. Consequently, a powerful artificial intelligence called genetic algorithms (GA) is used to determine the best combination of the control variable settings. In the next step the conformation test was conducted for the optimal parameter settings and found good agreement between the GA kerf and measured kerf. Hence, it is clearly reveal that the effectiveness and accuracy of the developed model and program to analyze the kerf and to determine its optimal process parameters. The results obtained in this work states that, the resulted optimized parameters are capable of machining the Al7075/SiCp MMCs more efficiently and with better dimensional accuracy.
Abstract: We propose an unconstrained measurement system for scratching motion based on mathematical model of unconstrained bed sensing method which could measure the bed vibrations due to the motion of the person on the bed. In this paper, we construct mathematical model of the unconstrained bed monitoring system; and we apply the unconstrained bed sensing method to the system for detecting scratching motion. The proposed sensors are placed under the three bed feet. When the person is lying on the bed, the output signals from the sensors are proportional to the magnitude of the vibration due to the scratching motion. Hence, we could detect the subject’s scratching motion from the output signals from ceramic sensors. We evaluated two scratching motions using the proposed system in the validity experiment as follows: 1st experiment is the subject’s scratching the right side cheek with his right hand, and; 2nd experiment is the subject’s scratching the shin with another foot. As the results of the experiment, we recognized the scratching signals that enable the determination when the scratching occurred. Furthermore, the difference among the amplitudes of the output signals enabled us to estimate where the subject scratched.