Ceramic Firing Research Articles

Change in Color and Gloss Parameters of Stained Monolithic Resin-Ceramic CAD/CAM Materials After Simulated Aging: An In Vitro Study.

To measure the effect of simulated aging on stained resin-ceramic CAD/CAM materials regarding the durability of color and gloss. Test specimens (n = 15 per material) were prepared out of CAD/CAM ingots from two resin nanoceramics (Lava Ultimate [LVU], Cerasmart [CER]) and a polymer-infiltrated ceramic (ENA, VITA Enamic) stained with the manufacturer's recommended staining kit using photopolymerization. Control specimens were made of feldspathic ceramic (VITA Mark II [VM2]) and stained by means of ceramic firing. Negative control specimens (n = 15) (no staining) were prepared for each group. Color and gloss measurements were performed before and after each aging cycle by means of mechanical abrasion with a toothbrush. Groups were compared using Kruskal-Wallis test and paired post hoc Conover test. Changes within a group were calculated using Wilcoxon signed-rank test (α = .05). The color difference (ΔE) was statistically significant for all stained CAD/CAM materials after simulated aging: CER (P < .001, 95% CI: 2.96 to 3.69), LVU (P = .004, 95% CI: 1.09 to 1.46), ENA (P = .004, 95% CI: 0.20 to 0.42), and VM2 (P < .001, 95% CI: 0.29 to 1.08). Aging resulted in a statistically significant increase in gloss in the LVU group (P < 0.001, 95% CI: 13.78 to 17.29), whereas in the ENA (P < .001, 95% CI: 7.83 to 12.72), CER (P < .001, 95% CI: 2.69 to 8.44), and VM2 (P = .014, 95% CI: 0.22 to 1.87) groups, a significant decrease in gloss was noted. Color and gloss of stained resin-ceramic CAD/CAM materials changed significantly after aging by means of toothbrush abrasion in vitro.

Genealogies and Juxtapositions: Traces of Potting Communities and Firing Facilities in Lake Titicaca Basin

In this paper, we develop a genealogy of practice approach for the historical analysis and comparison of Andean ceramic firing. This effort was set in motion by the similarity of two sets of ash mounds observed in the Lake Titicaca Basin of Bolivia, one modern and one from the Late Intermediate Period (A.D. 1100–1450). We eschew an ethnoarchaeological perspective in favor of considering their position within a longer genealogy of potting practice. We argue that a genealogical perspective foregrounds ephemeral evidence that is often ignored in dominant narratives, highlights the emergent nature of practices, and draws attention to subject formation across generations. We examine the extant data for pottery firing in the region, drawing out the genealogy of practices involved in firing facilities and subject formation from the Formative Period (1500 B.C. –A.D. 450) through the present. We then return to the ash mounds, juxtaposing the practices and archaeological traces to consider their historical emergences. These two approaches allow us to begin to map out the particularities of Lake Titicaca Basin production locales and to pose new questions of the social relations associated with ceramic firing contexts.

Application of Evolved Gas Analysis Technique for Speciation of Minor Minerals in Clays

Mineralogical characterization of clays used in manufacturing of traditional ceramic products is critical for guarantee the quality of the final product, but also for assessing the environmental impact of the industrial process in terms of atmospheric emissions. In fact, the presence of impurities even in low-level concentrations can have a big impact. So, it is very important to carry out an accurate mineral quantification of those minerals which are related to carbon dioxide and acid emissions (hydrogen fluoride, hydrogen chloride or sulfur dioxide). The development of hyphenated techniques coupling thermal analysis equipment with mass spectrometry and Fourier-transform infrared spectroscopy provides more valuable information and lower limit quantification than other primary techniques, such as X-ray diffraction or infrared spectroscopy. The main objective of this work is to develop an analytical procedure using evolved gas analysis to identify and quantify minerals such as chlorides, sulfides, carbonaceous materials and minor clay minerals. In addition to this, the study includes the analysis of acid emissions during the ceramic firing treatment even if they are present at low quantitative levels. This methodology was applied to reference materials so that it allows the identification of sulfur, chlorine, fluorine and carbonaceous compounds in concentrations lower than 1%.

Evaluation of the application of macrophyte biomass Salvinia auriculata Aublet in red ceramics

In this work, the study of the biomass application of a microphyte plant Slavinia auriculata Aublet in red ceramic was carried out. The waste comes from the phytoremediation process, used in sewage treatment plants. Characterization tests were carried out by chemical, mineralogical, dilatometry, thermal and mass spectrometry techniques, where it was possible to prove that biomass is compatible in its composition for application in ceramic materials and also has great potential to act as a source of energy. The production of specimens was carried out using an industrial clay mass and incorporating 0–10% of biomass in samples produced by pressing and burned at temperatures between 750 and 1050 °C. Properties of plasticity, firing shrinkage, apparent drying and firing density, water absorption, compressive strength and tensile strength in flexion were evaluated, where the feasibility of using up to 2.5% biomass in ceramics firing in 1050 °C s was proven. Although the results of water absorption at the firing temperature of 1050 °C have increased from 18.3% to 19.4% with the use of 2.5% of the residue, the results of tensile strength in flexion have reduced from 4.80 to 3.75 MPa and the results of compressive strength have reduced from 27.6 to 22 MPa, the values obtained meet international recommendations and are in accordance with the recommendations of the bibliography. Finally, an economic analysis of the application of biomass in ceramic materials was carried out, where it was observed that it was possible to save up to 5.04% with the use of the biomass under study, providing an annual savings of $ 2668.8 for the ceramic industry.

Viscous deformation as a measure of heat work during coal ash fusibility testing

Coal ash fusibility is important in evaluating coal quality and managing coal ash in boilers and gasifiers. Ash fusibility test (AFT) data constitute the basis for many ash and slag management models. Coal ash is a mixture of inorganic compounds derived from sedimentary minerals. As is the case for the bending of pyrometric cones used to control the firing of traditional ceramics, the deformation of coal ash cones is a measure of heat work and not temperature. Heat work, the combined effect of time and temperature, is measured by cone deformation that results from the integration of viscous strain over time. The effective viscosity of 4726 coal ash samples from the U.S. Geological Survey Coal Quality (COALQUAL) database were evaluated at their AFT critical temperatures and found to be lower than the working range of glass, which is consistent with the heat work interpretation of AFT critical temperatures. Thermophysical model data also showed strong positive linear correlations between AFT critical temperatures and the liquidus temperature, as was also the case for pyrometric cones, but not with their solidus temperatures. The finding provides a thermophysical basis for AFT models based on composition while also explaining the spurious correlation between the critical viscosity temperature (TCV) in coal ash slags and AFT critical temperatures. Silicate liquid immiscibility and phase inversion between iron-rich and iron-poor phases results in a sharp change in the effective viscosity of the slag emulsion. High effective viscosities magnify the effect of heating rate variability on AFT critical temperature measurements.

Ceramic firing protocols and thermocycling: effects on the load-bearing capacity under fatigue of a bonded zirconia lithium silicate glass-ceramic

This study evaluated the effect of different firing processes (without firing, additional crystallization and glaze firing) and thermal-cycling (with or without) on the fatigue behavior of simplified zirconia-lithium silicate (ZLS) glass ceramic restorations cemented to a dentin-like material. Materials and Methods. One hundred twenty-nine (129) discs (diameter = 12 mm and thickness = 1.2 mm) of ZLS (Celtra Duo, Dentsply Sirona) and fiber-reinforced epoxy resin (diameter = 12 mm and thickness = 2.3 mm) were produced and tested under fatigue according to 2 study factors: a firing protocol with 3 levels (without firing, additional crystallization and glaze firing) and thermocycling of 2 levels (absence/presence), composing 6 study groups. Ceramic and epoxy resin discs had their surfaces treated and adhesive cementation was performed (Multilink N, Ivoclar). Half of the samples were immediately tested; the other half were subjected to thermal-cycling (10,000 cycles in water; 5-55 °C). The staircase method determined the fatigue failure load (100,000 cycles at a frequency of 20 Hz). The fatigue data (in N) were submitted to 2-way ANOVA and Bonferroni test (p < 0.05). Fractographic analyses were also carried out. Thermocycling decreased the fatigue failure load (FFL) of all groups when compared to those without aging. Bonferroni's test indicated that the groups with crystallization/glazing process behaved better in terms of FFL than those without firing in the same storage condition. All the samples had radial cracks and all fractures originated from defects on the cementation surface of the ceramic discs. Crystallization and glaze firing had a positive effect on the fatigue failure load of adhesively cemented ZLS glass ceramic compared to the group without crystallization firing, in both storage conditions (with or without thermocycling).

Evaluation of the influence of calcium carbonate on the firing process and sintering time

This paper presents the use of calcium carbonate as an additive in the manufacturing process of ceramic bricks, in order to reduce the temperature and sintering time of the clays and to improve the quality of the products. In the study, samples of solid bricks with two different proportions were made. One was composed of 100% clay and the other of 70% clay and 30% calcium carbonate, which were fired in an intermittent kiln. The temperatures of the firing process were recorded using a virtual instrument. The samples manufactured were tested for water absorption and strength. The addition of calcium carbonate brought advantages such as an 8.66% decrease in fuel consumption, a 23.88% decrease in firing time, a 12.11% and 26.67% decrease in the firing temperature and gases released into the environment, respectively, as well as improvements in the quality of the product. The use of calcium carbonate as an additive decreased the time and temperature of ceramic firing and fuel consumption and increased energy efficiency, productivity and product quality, as well as reduced gas emissions into the environment.

Influence of porcelain firing on changes in the marginal fit of metal-ceramic fixed partial dental prostheses fabricated with laser sintering: An in vivo study.

Marginal fit is the most important criterion in the evaluation of the clinical acceptability of fixed restorations. Due to cement solubility and plaque retention, marginal gaps are potentially harmful to both the teeth and the periodontal tissues. The aim of the study was to investigate the accuracy of the fit of dental metal-ceramic bridges manufactured with the use of direct metal laser sintering (DMLS), and to explore the effects of porcelain firing on the marginal, axial and occlusal fit of metal-ceramic frameworks. The study involved 10 patients with 3-unit metal-ceramic restorations produced using the DMLS technique. Using the silicone replica technique, we examined the marginal, axial and occlusal fit of the dental bridges before and after ceramic firing. The Shapiro-Wilks normality test and Student's paired t‑test were implemented to analyze the mean differences in the marginal, axial and occlusal fit of the restorations before and after ceramic firing. A 95% confidence interval (CI) and discrepancy values at the level of 1% and 0.1% (p > 0.05) were applied. All the mean values of the measurements of marginal (156.08 μm), axial (95.75 μm) and occlusal (252.83 μm) gaps were lower before ceramic veneering than after ceramic veneering, when the mean value for the marginal gap was 178.17 μm, for the axial gap - 106.75 μm and for the occlusal gap - 266.00 μm. Porcelain firing caused no statistically significant differences in the discrepancy values of marginal, axial and occlusal fit. For clinical application, further improvement of the DMLS system is highly recommended. Marginal gaps in DLSM bridges significantly exceed the permissible inaccuracy values of 100-120 μm for prosthetic restorations.

Firing of Cellular Ceramics from Granulated Foam-Glass

It has been presented the study results of the firing process of cellular ceramics from granulated foam glass. The chemical, mineral and granulometric compositions of the raw materials are given. It has been shown the characteristic of ceramic-technological properties of raw materials. The samples were burned from the granulated mixture in the temperature range of 850-1000 ° C. It has been established the change dependence in the physicomechanical properties of cellular ceramic samples on the temperature and firing duration. The results of the study of the macro-and microstructure of cellular ceramics are given. It has been revealed the effect of intensive formation of the pyroplastic phase and the connection between small pores at a temperature of more than 950 ° C. After the enlargement, the cells leave the three-phase ceramic system and it was the increase in the average density of cellular ceramics is 1.4-1.5 times. The influence of a solid glass-ceramic shell along the inner surface of the pores on the decrease in water absorption of cellular ceramics to 6.5-7% is established.

Biomaterial Embedding Process for Ceramic-Polymer Microfluidic Sensors.

One of the major issues in microfluidic biosensors is biolayer deposition. Typical manufacturing processes, such as firing of ceramics and anodic bonding of silicon and glass, involve exposure to high temperatures, which any biomaterial is very vulnerable to. Therefore, current methods are based on deposition from liquid, for example, chemical bath deposition (CBD) and electrodeposition (ED). However, such approaches are not suitable for many biomaterials. This problem was partially resolved by introduction of ceramic–polymer bonding using plasma treatment. This method introduces an approximately 15-min-long window for biomodification between plasma activation and sealing the system with a polymer cap. Unfortunately, some biochemical processes are rather slow, and this time is not sufficient for the proper attachment of a biomaterial to the surface. Therefore, a novel method, based on plasma activation after biomodification, is introduced. Crucially, the discharge occurs selectively; otherwise, it would etch the biomaterial. Difficulties in manufacturing ceramic biosensors could be overcome by selective surface modification using plasma treatment and bonding to polymer. The area of plasma modification was investigated through contact-angle measurements and Fourier-transform infrared (FTIR) analyses. A sample structure was manufactured in order to prove the concept. The results show that the method is viable.

Research on diversified application of modular high temperature ceramic kiln

Modular ceramic kiln can meet more than 10 kinds of ceramic firing technology, such as carburizing, wood burning, soda burning,Shinoya, oxidation firing, reduction firing, which adopt a full range of safety warning device, monitor and record the whole process of fire, guarantee the stability of the firing process, and provide reference data for the next fire. Modular ceramic kiln can meet various of ceramic kiln firing technology after physical kiln experiments, and has many advantages such as less investment, quick effect, broad use, etc. which can be widely used in the laboratory of colleges, universities and scientific research process.

Development of a Model for Color Formation and Distribution of a Coloring Component During of the Firing of Ceramics of Frame-Painted Structure

Development of a Model for Color Formation and Distribution of a Coloring Component During of the Firing of Ceramics of Frame-Painted Structure

Study on Microwave Sintering Process and Surface Texture Characteristics of Ceramic Materials

The sintering process and properties of nano-cermet materials were studied by microwave sintering new technology. The results show that the microwave sintered Al2O3-TiC-Mo-Ni nano-ceramics can reach a relative density of 99.0% when kept at 1500 °C for 10 min; the sintering temperature is lowered, the sintering time is greatly shortened, and the grains are sintered before and after sintering. The diameters are 35 and 55 nm, respectively, with little change. At the same time, the paper discusses the surface texture formation and aesthetic characteristics of ceramic materials after sintering. The paper hopes to contribute to the art ceramics firing and decoration field.

Influence of ceramic firing on marginal gap accuracy and metal-ceramic bond strength of 3D-printed Co-Cr frameworks

Statement of problemThe marginal gap and ceramic bond strength of metal-ceramic restorations are important for success. However, studies evaluating the marginal gap and ceramic bond strength of fixed partial dentures (FPDs) produced with 3D printing technologies such as selective laser melting (SLM) are scarce. PurposeThe purpose of this in vitro study was to investigate the marginal gap of cobalt-chromium (Co-Cr) alloy frameworks produced by SLM technology before and after ceramic firing. Additionally, the metal-ceramic bond strength was evaluated with the Schwickerath crack-initiation test according to the International Standards Organization (ISO) 9693-1:2012. Material and methodsConventional impressions were made, and the definitive cast of a patient requiring a 4-unit FPD was scanned. After designing the FPD, the files were sent to a service center for the fabrication of a metal master model, 80 Co-Cr frameworks, and 80 flat specimens (25×3×0.5 mm) with SLM technology. The marginal gap between frameworks and the abutment tooth of the metal master model was nondestructively measured by using an optical coordinate-measuring machine. A total of 80 sets, consisting of 1 framework and 1 flat specimen, were sent to 80 dental laboratory technicians for ceramic firing. Detailed instructions for correct manipulation of the framework and flat specimen were provided. The marginal gap was remeasured, and the 3-point bend test was used to evaluate metal-ceramic bond strength. ResultsOnly 28 of the 80 dental technicians returned the specimens within a prespecified time and/or in adequate condition. The mean ±standard deviation marginal gap of the framework before ceramic firing was 25 ±9 μm and 34 ±12 μm after firing. The difference was statistically significant (P=.001). The mean ±standard deviation 3-point bend strength was 33 ±9 MPa. ConclusionsCeramic firing affected the marginal gap; however, all Co-Cr frameworks had a marginal gap lower than 120 μm, which is reported to be a clinically acceptable limit. Most of the specimens (80%) had a metal-ceramic bond strength value higher than the 25-MPa ISO 9693 requirement. Five of 28 dental laboratory technicians were not able to comply with ceramic firing instructions.

Evaluation of two different CAD-CAM inlay-onlays in a split-mouth study: 2-year clinical follow-up.

To evaluate the clinical performance of hybrid ceramic inlay-onlay restorations over a 2-year period. A total of 30 lithium disilicate glass ceramic (LDC; control group) and 30 hybrid ceramic (HC; test group) inlay/onlay restorations were performed in 14 patients. Clinical evaluations were performed after 1 week, 6 months, 1 year, and 2 years of cementation according to the modified United States Public Health Service (USPHS) criteria, gingival index, and plaque index. The Friedman test was used for the significant difference in time and Wilcoxon signed-rank test was used for the determination of differences. The clinical parameters, gingival and plaque indexes differences in time were analyzed with Chi-square test. No statistically significant difference (P > .05) was found between the two groups in the modified USPHS, gingival index, and plaque index evaluations, whether statistically significant differences were found within groups. The total survival rate was 100% for both groups after 2 years. Based on the 2-year data, the tested HC can be considered a reliable material for inlay/onlay restorations. The results of this in vivo study suggest that both resin nanoceramic materials and LDC materials have been successfully incorporated in treatments of inlay and onlay restorations. Short-term results showed that resin nanoceramic materials can be counted as a good choice in inlay and onlay restorations in an effort to reduce the treatment time associated with ceramic firing processes.

Effects of temperature non‐uniformity and effective viscosity on pyrometric cone deformation

AbstractPyrometric cone deformation is used to measure heat work or the combined effect of temperature and time during ceramic firing. Finite‐element analysis shows that stationary‐state temperature non‐uniformity in a pyrometric cone during constant‐rate heating can account for differences in observed endpoint temperatures at different heating rates. Thermophysical modeling provides evidence that two‐phase viscous flow plays an important role in pyrometric cone deformation. The Einstein‐Roscoe equation is used to calculate the effective viscosity of partially molten pyrometric cones during viscous flow deformation, with the solid phase volume fraction determined through thermophysical modeling and the molten phase viscosity estimated with the Modified Quasichemical Model. A correlation was found between the endpoint deformation temperatures of pyrometric cones and corresponding Littleton softening point temperatures; however, the approach fails when viscous flow is not the principal deformation mechanism and when the initial glass fraction exceeds the equilibrium molten phase fraction predicted by thermophysical modeling.

Investigations of potsherds of miniature cups and household pots from the first millennium AD (the case study on the Western Lithuanian ceramics)

This article presents data on the structure and elemental composition of hand-built miniature cups with a smooth surface, that were enclosed into burials as funeral pottery, and household pots dated to the first millennium AD found in four different archaeological sites of Western Lithuania. Investigated funeral and household pottery samples reflect the chemical composition of the local raw materials used for their production, while the variations in composition point to different clay locations, as well as use of distinct tempers and peculiarities of ceramics firing technology.

Study on firing temperature of the Song Dynasty (960\u20131279AD) greenish-white porcelain in Guangxi, China by thermal expansion method

The original firing temperatures of porcelain pieces unearthed from Tengxian Zhonghe kiln, Rongxian Chengguan kiln, Beiliu Lingdong kiln and Guiping Xishan kiln from the Song Dynasty (960–1279AD) of Guangxi were preliminarily studied by thermal expansion method. The experiment results show that the average firing temperature of Zhonghe kiln is 1186 °C (standard deviation 59 °C), the firing temperature relatively concentrated and low. The average firing temperature of Chengguan kiln is 1233 °C (standard deviation 46 °C), with the majority above 1200 °C, indicating that the kiln had a high and concentrated firing temperature. The average firing temperature of Lingdong kiln is 1250 °C (standard deviation 87 °C), the firing temperature are in a broad spectrum. The firing temperatures of Xishan kiln are mostly over 1300 °C (average 1307 °C, standard deviation 75 °C), which are generally considered very high, and the highest one it can go up to 1456 °C, which is the highest firing temperature of ancient Chinese ceramics known to date. Compared with the firing temperature of porcelain in other regions of China in Song Dynasty, it can be concluded that the high-temperature technology of Guangxi porcelain kilns was equal to or even advanced than other kilns. In the light of these findings, we conclude that the ancient Guangxi region of China did not lag behind the central plains in terms of ceramic firing technology and culture.

Numerical analysis of the transient heat transfer in high temperature chamber furnaces

An algorithm for numerical analysis of the transient thermal processes in high temperature gas chamber furnaces for ceramic firing is developed. It is based on mathematical models of the conjugate heat transfer, including combustion, turbulent flows of the torch and gas mixtures, heat transfer through radiation, conduction and convection. The algorithm is used for analysis and improvement of the efficiency of a furnace for firing of technical ceramics.

Influence of CRT Glass Quantity on the Properties of Red Mud-CRT Glass Ceramics Fired at Different Temperatures

Influence of CRT Glass Quantity on the Properties of Red Mud-CRT Glass Ceramics Fired at Different Temperatures