Types Of Porcelain Research Articles

A comparison of debonding strengths of four metal-ceramic systems with and without opaque porcelain

When performing an adjustment on metal-ceramic restorations, opaque porcelain may become exposed, particularly on the lingual surface of maxillary anterior teeth. It is generally believed that exposed opaque porcelain can be more abrasive and destructive to an opposing dentition than body porcelain, and that these teeth may require restoration as a consequence. This study compared the debonding strengths of 2 types of porcelain, with and without opaque porcelain, to 2 types of dental casting alloys. Two porcelain systems, Ceramco3 and Vita 900, and 2 metal alloys, a high noble (Encore) and a base metal (Duceranium U), were used to fabricate and test 56 flexure bars in accordance with ISO 9693:1999(E): Metal-Ceramic Dental Restorative Systems. Half of the bars received opaque porcelain prior to body porcelain additions, and the other half did not. The metal-ceramic debonding strength was determined by using a 3-point flexure apparatus and a mechanical testing device (Instron). A center load was applied at a crosshead speed of 1.5 mm/min(-1) until debonding occurred. In addition to the load-versus-displacement curve, a precision measurement microphone was used to assist in ascertaining the point in time when debonding occurred. Since the sound analysis and the mechanical test were started simultaneously, the debonding load could be more accurately determined. Data were statistically analyzed using 3-way analysis of variance, and all pairwise multiple comparisons were made with the Tukey HSD test (alpha=.05). The difference in mean debonding strength values for opaqued and non-opaqued flexure bars were statistically significant (P=.028). The mean debonding strength values (MPa) for each metal-ceramic system were as follows: Encore-Opaque-Ceramco3 (EOC), 31.43 +/- 6.92(a); Encore-Opaque-Vita 900 (EOV), 30.37 +/- 3.25(a); Duceranium U-No Opaque-Ceramco3 (DNC), 29.20 +/- 6.97(a); Duceranium U-Opaque-Ceramco3 (DOC), 26.61 +/- 4.98(a); Duceranium U-Opaque-Vita 900 (DOV), 26.15 +/- 4.29(a); Encore-No Opaque-Vita 900 (ENV), 25.45 +/- 4.04(a); Encore-No Opaque-Ceramco3 (ENC), 23.96 +/- 4.14(a); Duceranium U-No Opaque-Vita 900 (DNV), 22.88 +/- 6.15(a). Identical superscript letters denote no significant difference among groups. The precision measurement microphone resulted in selection of a debonding strength/crack initiation load that was lower than the peak load recorded during strength testing. Initial debonding during crack initiation strength testing may not always correspond to the peak load recorded, but rather to the point on the load-versus-displacement curve beyond which the relationship is no longer a straight line. Presence of opaque porcelain generally increased the debonding strength for metal-ceramic systems; however, opaque porcelain may not be necessary for a clinically acceptable metal-ceramic bond for some metal-ceramic systems.

Evaluation of a plastic clay from the state of Rio de Janeiro as a component of porcelain tile body

The objective of this work was to evaluate the possibility of using a clay from the city of Silva Jardim, State of Rio de Janeiro, Brazil, in the composition of porcelain tile body. The clay investigated was a plastic kaolinitic type with white color. Initially, a typical porcelain body composed of the mixture of this clay with feldspar, quartz, kaolin and talc was prepared. Specimens were then obtained from this porcelain mixture by uniaxially pressing samples until a dry density of 2.0 g/cm3 was achieved. These specimens were then fired at 1180°C in a laboratory furnace. Physical and mechanical properties related to linear shrinkage, water absorption and flexural rupture strength, determined by Weibull statistical method, were evaluated. Microstructural analysis for the experimental body was performed by scanning electron microscopy, X-ray diffraction and mercury porosimetry. The technological properties of the elaborated composition satisfied the porcelain tile standard specifications. The microstructural analysis displayed small pores as well as a glassy matrix. The presence of quartz, mullite and plagioclase were also detected in the fired porcelain tile. These results indicated that the clay presents satisfactory characteristics to be used in porcelain tile body.

Produção de porcelana de ossos e caracterização de suas propriedades técnicas

A porcelana de cinza de ossos é amplamente aceita e alcança alto valor de mercado, entretanto, sua produção ainda é pouco difundida, de modo que sua fabricação e pesquisa são restritas a poucos países. Sendo o Brasil grande produtor de gado, apresenta grande potencial para a reciclagem de ossos, podendo-se encontrar aplicação destes em materiais cerâmicos. Neste trabalho foi feita uma análise comparativa das características técnicas entre uma formulação de porcelana obtida com cinzas de ossos conforme a receita tradicional inglesa e uma formulação de porcelana tradicional. Os resultados mostraram que a sinterização de porcelana de cinzas de ossos requer cuidados extras em ciclos rápidos de queima quando comparada à porcelana tradicional, devido a um menor intervalo de gresificação. No entanto, a maior resistência mecânica e as qualidades estéticas, destacando-se a elevada alvura, fazem desta porcelana bastante atrativa em termos de potencial de aplicações industriais.

Communication Between the Dental Laboratory Technician and Dentist: Work Authorization for Fixed Partial Dentures

A questionnaire was sent to laboratory technicians to determine the level of communication between dentists and dental laboratories in specific areas of the work authorization forms for the fabrication of fixed partial dentures. A select number of dental laboratories were randomly chosen from the National Association of Dental Laboratories (NADL) for each of the 50 states. The questionnaire was mailed to the laboratory directors for a total of 199 dental laboratories. The survey asked questions pertaining to the following areas of work authorization: legibility and thoroughness of prescriptions, patient information, choice of materials for the prosthesis, design of the prosthesis, and shade description. For each question, the number of responses received was tabulated and converted to a percentage. Of the 199 laboratories surveyed, 114 (57%) responded to the questionnaire. Results from this survey suggest that there is lack of communication between dentists and dental laboratories through work authorization forms regarding choice of metal alloy, type of porcelain to be used, and choice of margin and pontic design for the prosthesis. Information obtained from the responding laboratories included effectiveness of work authorization forms. There were some similar trends indicated by the large percentage of dental laboratories agreeing on lack of communication by the dentists as reflected by the work authorization forms.

History of vacuum circuit breakers and recent developments in Japan

Vacuum circuit breakers (VCBs) have been developed and widely applied in Japan to meet the requirements of increasing energy consumption and also in national security of various areas. As a result, for example, a 168 kV two break porcelain type and a 100 kA one break VCB have already appeared in the Japanese market and they are currently being exported to world-wide markets. VCBs interrupt currents in vacuum, and this means they do not exhaust dissolved gases which are sometimes harmful to the human body or cause effects on the environment. Therefore, by its nature, the recycling of materials and safety to the human body have been realized, and also no global warming effects would be expected. Energy is extremely essential and important in human daily life, and many types of circuit breakers play important roles in electrical power transmission and distribution systems to maintain the systems reliability and safety by switching the systems under several conditions. Since vacuum circuit breakers possess a lot of advantages such as high current interrupting capabilities, small size, and low cost, they will be used much more in the future, and at this moment, we believe it is very worthy to discuss and consider thoroughly future trends of VCBs. In this paper, the results of the developments in Japan will be reviewed, the reflection of the results will be stated, and the subjects of engineering in the 21st century will be discussed. These will include recycling, safeguards to the human body and the fireless nature of VCBs; and it will be demonstrated that the developmental works of VCBs are being wonderfully explored in Japan now and in the future.

Effect of waste glass and zircon on ceramic properties and microstructure of porcelain tiles

The possibility of using waste glass as a flux in porcelain tiles without deterioration in mechanical properties has been assessed. Waste glass was added to a typical porcelain tile body, replacing feldspar by up to 15%. Zircon was also added at 5% in partial replacement of quartz. The prepared batches were fired at temperatures of 1160 to 1240°C with 20 min soaking time. Addition of 5% zircon in the presence of 5% waste glass resulted in unusual mechanical and physical characteristics. Further additions of waste glass enhanced vitrification and consequently some surface and mechanical properties, but worsened modulus of rupture (MOR) and toughness. Generally specimens containing zircon had better physicomechanical properties.

Ultrasonic non-destructive diagnostics of ceramic line insulators

Failures of high-voltage systems that recently occurred in Europe and USA resulted in the growth of an interest in problems concerning certainty of supply as well as security of exploitation of electrical power lines. This problem is also current in Poland. The serious failure in Warsaw in November 2004 proved the importance of this topic [1] . As a result of the fracture of two strain line insulators, 15% of power was shut off. About two hundred thousand inhabitants of five districts, and the underground and airport transportation systems were afflicted with blackouts for several hours. The main cause of a breakdown was ageing degradation of the material of insulators which had been in operation for over 30 years. This work presents a non-destructive ultrasonic investigation of a group of 15 line insulators of LP 75/17 type. These elements, made 'of C 120 type porcelain, have been in operation for about 30 years. The direct reason for this work was the mechanical breakdown of the line strain insulator on the 110/6 kV power engineering installation. On the basis of the measurements the cause of breakage was ascertained and an analysis was carried out of the quality of the tested insulators.

Waste glass in porcelain

In this work, the feldspar used as a flux in typical porcelain was replaced by waste glass, and the resulting batch composition contained 50% kaolin, 25% quartz and 25% waste glass. The properties of this porcelain with glass powder (GP) were compared to traditional porcelain (TP), which utilizes feldspar. The samples were fired at different temperatures, ranging from 1200 °C to 1400 °C. Technical parameters, such as water absorption, modulus of rupture and K IC, phase analysis by XRD, and microstructure by SEM were analysed. The results indicated that the lower fracture toughness and MOR of GP is a consequence of the peculiar microstructure of this porcelain. The reduction in firing temperature and the use of a cheaper substitute for feldspar makes GP also an attractive economical alternative.

The influence of some different factors on the accuracy of shade selection.

The purpose of this study was to elucidate some of the factors on which accurate shade taking depends. Custom shade tabs (0.5, 1.0 and 1.5 mm porcelain thickness) were fabricated from selected Vita and Shofu porcelains. Four main factors were investigated, namely, the difference between the two types of porcelain used, the effect of light quality, the effect of porcelain thickness and the experience of the observer. The chi-square test for independence at a probability level of P <0.05 was used to analyse the results. The results indicated that in ideal light there was no difference between the two porcelains (P=0.58). The experienced observers proved better than the novice observers in ideal light conditions (P=0.003). Thickness was also significant in the overall results (P=0.0001), in that thicker samples gave more accurate results. The results indicate that in adverse light, there was an overall difference between the two porcelains (P=0.046), but no difference between the experienced and novice observers. The thickness made no difference to the experienced or the novice observer in adverse light. These results indicate that the most influential factor on shade taking was the light quality (P <0.0001); better results were obtained overall for the ideal light situation. In ideal light thicker samples gave better results (P=0.0001).

Influence of powder/liquid mixing ratio on porosity and translucency of dental porcelains.

Dental technicians use a variety of techniques when condensing dental porcelains. It is unclear whether these techniques affect the total porosity and translucency of dental porcelains. The objective of this study was to determine whether varying the powder/liquid ratio during condensation affects porosity and translucency of porcelains. Material and methods Duceram LFC dentin, Duceram LFC incisal, IPS Eris dentin, and IPS Eris incisal porcelains were studied. For each specimen, 1.0 g of porcelain powder was mixed with 1 of 3 different volumes of deionized water to form a slurry with a thin, medium, or thick consistency. The slurries were condensed in a plastic syringe mold, fired, and polished to a 3-microm finish to form 12 groups of 4 specimens each (14-mm diameter, 1.10-mm thickness). The apparent density (g/mL) of each specimen was measured using Archimedes method, and the porosity (%) calculated. Each specimen was coupled to standard ceramic tiles using an immersion liquid, and the color shade was measured in CIE Yxy coordinates using a tristimulus colorimeter. Translucency was assessed by calculating the contrast ratio of shade value (Y) in front of black versus white backgrounds. Two-way analysis of variance and Tukey's multiple comparison tests (alpha = .05) were used to test for significant effects of factors. Porcelain type and powder/liquid ratio had a significant interactive effect on the apparent density (P < .001) and on total porosity (P = .003); however, there was no consistent trend. The powder/liquid ratio did not significantly affect translucency (P = .28), but porcelain type had a significant effect on translucency (P < .001). In this in vitro study, total porosity of specimens prepared using 4 porcelains was found to be sensitive to powder/liquid ratio; whereas translucency was found to be insensitive to powder/liquid ratio.

Fluorescent Properties of Porcelain-Restored Teeth and Their Discrimination

The differentiation of porcelain from tooh using fluorescence emission was investigated as a basic research for the visual detection of porcelain-restored teeth in mass dental health examinations. The fluorescence spectra were taken from the extracted human maxillary central incisors and five types of porcelain by excitation using the light 380-470 nm. There was a clear difference in fluorescence intensity between tooth and porcelain using excitation longer than 400 nm. Tooth and porcelain could be successfully distinguished on an image photographed by fluorescent light.

Evaluation of low-fusing ceramic systems combined with titanium grades II and V by bending test and scanning electron microscopy

The bond strength by three point bending strength of two metal substrates (commercially pure titanium or grade II, and Ti-6Al-4V alloy or grade V) combined to three distinct low-fusing ceramic systems (LFC) and the nature of porcelain-metal fracture by scanning electron microscopy (SEM) were evaluated. The results were compared to a combination of palladium-silver (Pd-Ag) alloy and conventional porcelain (Duceram VMK68). Sixty metal strips measuring 25x3x0.5mm were made - 30 of titanium grade II and 30 of titanium grade V, with application of the following types of porcelain: Vita Titankeramik, Triceram or Duceratin (10 specimens for each porcelain). The porcelains were bonded to the strips with dimensions limited to 8x3x1mm. The control group consisted of ten specimens Pd-Ag alloy/Duceram VMK68 porcelain. Statistical analyses were made by one-way analysis of variance (ANOVA) and Tukey test at 5% significance level. Results showed that the bond strength in control group (48.0MPa ± 4.0) was significantly higher than the Ti grade II (26.7MPa ± 4.1) and Ti grade V (25.2MPa ± 2.2) combinations. When Duceratin porcelain was applied in both substrates, Ti grade II and Ti grade V, the results were significantly lower than in Ti grade II/Vitatitankeramik. SEM analysis indicated a predominance of adhesive fractures for the groups Ti grade II and Ti grade V, and cohesive fracture for control group Pd-Ag/Duceram. Control group showed the best bond strength compared to the groups that employed LFC. Among LFC, the worst results were obtained when Duceratin porcelain was used in both substrates. SEM confirmed the results of three point bending strength.

Application of ICP-MS trace element analysis in study of ancient Chinese ceramics

Thirty-nine trace elements of the Song-Yuan period (960–1368 AD) porcelain bodies from Cizhou, Jizhou and Longquanwu kilns were analyzed with ICP-MS, a technique rarely used in Chinese archaeometry, to investigate its potential application in such studies. Trace element compositions clearly reflect the distinctive raw materials and their mineralogy at the three kilns and allow their products to be distinguished. Significant chemical variations are also observed between Yuan and Song-Jing dynasties samples from Cizhou as well as fine and coarse porcelain bodies from Longquanwu. In Cizhou, porcelains of better quality which imitate the famous Ding kiln have trace element features distinctive from ordinary Cizhou products, that indicates geochemically distinctive raw materials were used and which possibly also underwent extra refining prior to use. The distinct trace element features of different kilns and the various types of porcelains from an individual kiln can be interpreted from a geochemical perspective. ICP-MS can provide a large amount of valuable information about ancient Chinese ceramics as it is capable of analyzing >40 elements with a typical of precision < 2%.

A rose by any other name: a geochemical comparison of Caughley (c. 1772–99), Coalport (John Rose & Co.; c. 1799–1837), and rival porcelains based on sherds from the factory sites

Compositional data for sherds from various Shropshire factory sites show that at the Coalport works, John Rose and colleagues produced two types of true porcelain that differed in their phosphate content, and bone-ash porcelain. The low-phosphate true porcelain is compositionally similar to its Caughley counterpart; there is, however, no knwn analogue to the relatively phosphatic (0.7–2.7 wt.% P2O5) true porcelain, which appears to have been produced between c. 1795 and the 1830s. All of the analysed Coalport true porcelain sherds are in biscuit, indicating an ‘artificial-porcelain type’ firing sequence. Had they been glazed, the glaze would likely have been lead-rich, as is the case of the glazed true porcelain sherds from the Caughley factory.Soapstone (magnesian) porcelains from the Caughley site resemble Flight-period Worcester porcelain in terms of the concentration of their plastic ingredients (soapstone and clay), but they can have small amounts of fluxing components (lead, alkalis). This indicates that Turner sought to produce a paste with a similar degree of plasticity as Worcester, but he either could achieve and control higher kiln temperatures, or at times was satisfied with a somewhat less vitrified ware. The latter inference is supported by mineralogical and modal melt data, and the rather crude character of some of Turner’s mass-produced wares.Analysed Coalport phosphatic porcelain produced during the decade (1820s) when Nantgarw’s former proprietor (William Billingsley) worked at Coalport has a similar bone-ash/clay ratio (∼ 1.3) but a significantly lower K2O/Na2O ratio (∼ 1.9 versus 5.2) than Nantgarw porcelain. Another Billingsley-related ware, Swansea ‘duck egg’ porcelain (c. 1815–17) has an even more divergent composition, with lower phosphate contents and up to half again as much alumina as Nantgarw and c. 1820s Coalport. The data support the traditional view that Billingsley had little influence on Rose during his tenure at Coalport.

Effect of soda-lime glass on sintering and technological properties of porcelain stoneware tiles

The feasibility of waste glass recycling in ceramic tile production was assessed with special reference to fully vitrified products (porcelain stoneware). Soda-lime float or container glass was introduced, in replacement of sodic feldspar, in typical porcelain stoneware bodies (up to 10 wt.%) that underwent a laboratory simulation of tilemaking process, with a technological and compositional characterization of both fired and unfired tiles. Soda-lime glass had no significant effect on semi-finished products, but it influenced remarkably the firing behaviour, increasing shrinkage and closed porosity, decreasing open porosity and bulk density, and lowering mechanical and tribological performances. Waste glass promotes a more effective melting of quartz and a partial dissolution of mullite, leading to a more abundant and less viscous liquid phase, which accelerates the sintering kinetics. In conclusion, soda-lime glass can be used in small amounts (5% or less) with tolerable modifications of technological behaviour and performances of porcelain stoneware tiles.

Provenience of eighteenth-century british porcelain sherds from sites 3b and 4e, fortress of Louisbourg, Nova Scotia: Constraints from mineralogy, bulk paste, and glaze compositions

Twenty-six British porcelain sherds excavated from two properties at the Fortress of Louisbourg were analysed by electron microprobe with the objective of identifying the factories from which they originated (that is, their provenience). Nineteen of the samples are phosphatic; seven are magnesian. Sixteen of the phosphatic sherds have paste and glaze compositions consistent with Bow porcelain (ca. 1747 to 1776). This attribution is supported by underglaze blue patterns (Dragon, Cannonball, and Desirable Residence patterns) and famille rose overglaze polychrome designs that match the decoration used on Bow porcelain. A calcic plagioclase-bearing sherd has a composition suggesting derivation from the Gilbody works (Liverpool, ca. 1755 to 1761). Another unassigned sherd has a paste composition that resembles products of the Lowestoft factory (ca. 1757 to 1799), but contains plagioclase, a mineral not known to occur in Lowestoft porcelain, and its glaze contains small amounts of tin, a component unknown in analysed Lowestoft glazes. One highly porous sample has an anomalous composition (a lower phosphate content than any known bone-ash porcelain), and appears to have been chemically modified in the ground. It, too, remains unattributed. The magnesian sherds contain diopside and enstatite, and thus are mineralogically similar to another type of Liverpool porcelain (late Chaffers [ca. 1756 to 1765]) and its successor, the Christian/Seth Pennington works; ca. 1765 to 1799). Compositionally, the body and glaze of these samples resemble Chaffers/Christian/Seth Pennington porcelain. This attribution is further supported by their underglaze blue patterns, which match some of those (Liver Bird pattern) known to have been used at the Liverpool works. Contemporary documents record the fact that the Bow works exported significant amounts of its wares to North America. The discovery of Chaffers/Christian/Seth Pennington porcelain at Louisbourg and other archaeological sites in Atlantic Canada (Fort Beausejour) indicates that some Liverpool factories also supplied colonial markets with porcelain.

Determination of elastic properties of metal alloys and dental porcelains

This study aimed to determine Young's modulus, shear modulus and Poisson's ratio of some metal alloys and dental porcelains used in fixed prosthodontics using the technique of impulse excitation of vibration. It also aimed to compare Young's modulus values of these materials with those obtained using the other two methods: the four-point flexural test and the indentation test using the ultra micro-indentation system (UMIS). Five types of metal alloys and four types of dental porcelains were tested. The samples were prepared to a rectangular shape of approximately 8 x 30 x 1.5 mm. Frequency of vibration in a sample was read when a singular elastic strike was made with an impulse tool. The elastic constants were calculated from the frequency of vibration, dimension and mass of each sample. Young's modulus values resulting from the impulse excitation of vibration are not significantly different (P<0.05) from those obtained using the flexural test and the UMIS test in most metal alloys but are different in titanium, titanium alloy and most of the dental porcelains. The technique of impulse excitation of vibration has proven to be an accurate method and is simple to operate. The elastic properties of these alloys and porcelains are essential for determining the other mechanical properties (fracture toughness) and are relevant in clinical application.

Improved zinc oxide surge arresters using high voltage gradient 300 V/mm, 400 V/mm ZnO elements

Zinc oxide surge arresters using zinc oxide (ZnO) elements have been widely used for insulation coordination in the world's power systems. These ZnO elements have basically reference voltage of about 200 V/mm. Recently, new ZnO elements having about 1.5, 2 times high voltage gradient zinc oxide element have been developed. This paper describes applications of high voltage gradient 300 V/mm ZnO elements to high performance porcelain type surge arresters and oil immersed surge arresters, and 300 V/mm or 400 V/mm ZnO elements to gas insulated tank type surge arresters for power systems. Adequate selection of voltage gradient of ZnO elements makes more compact design of the surge arresters.

The Early Porcelain Kilns of Japan: Arita in the First Half of the Seventeenth Century.

This volume documents the porcelain pieces made in Japan in the first half of the 17th century, an era that encompasses the origins of the Japanese porcelain industry and the time of the export trade to Europe and the Near East. The book also offers a comprehensive reconstruction of the working practices of Japanese potters in the 17th century, assessing the individual kilns of Arita, where the porcelain was made, and looking at the workshop methods of today in order to throw light on possible 17th-century conditions. There are many photographs of fine examples, as well as of kiln-damaged pieces retrieved from kiln-sites, to show which kilns were working when producing which type of porcelain within the genre. The author thus demonstrates that the problematic porcelain of Old Kutani is nearly all of Arita manufacture.

二段積酸化亜鉛形避雷器の直流耐汚損特性の評価

二段積酸化亜鉛形避雷器の直流耐汚損特性の評価