The solid line represents the average value of Al2O3 UMF in the glass phase and the dotted lines represent the standard deviation. Firing conditions have consistently played a crucial role in the study of ancient ceramics for archaeologists. Model #2, which includes mullite crystallite size in the (110) direction, appears quite applicable due to an apparent variability in the ratio of primary to secondary mullite.
INTRODUCTION
LITERATURE REVIEW
Porcelain
Brief history of porcelain in China
In the history of Chinese ceramics, as early as the Neolithic era about 8,000 years ago, Chinese ancestors began to make pottery, mainly earthenware, by forming and firing the base. "Stamped Hard Pottery" which was slightly stronger and denser appeared in the early Shang Dynasty B.C.), followed by. During the Tang Dynasty (618-906 CE), pottery production in China was divided into two regions: north and south, each using different local raw materials. The kiln sites discovered in Jingdezhen were considered to be the earliest kilns to produce white porcelain (spelled "whiteware" in references) in southern China.
Porcelain development in Jingdezhen from Five Dynasties to Song Dynasty
- The geology advantages in Jingdezhen
- White porcelain in Five Dynasties and greenish white porcelain in Song
- Firing technology from Five Dynasties to Song Dynasty in Jingdezhen
- Porcelain stone
- Kiln evolution
- Firing furniture evolution
- Firing conditions
In general, the firing of furniture for the production of porcelain in Jingdezhen underwent dramatic changes from the Five Dynasties to the Song Dynasty. The Development of Furniture Firing from the Five Dynasties to the Song Dynasty under Jingdezhen Firing Conditions. Taking this into account, archaeologists believe that the production of porcelain from the Five Dynasties to the Song Dynasty in Jingdezhen was not very high, and that folk kilns were usually fired only once or twice a year.6, 18.
Current methods for determining the firing conditions of porcelain
However, limited accuracy and applicability over a limited temperature range is the obvious disadvantage of most firing temperature methods. What's more, there seems to be no technique available to estimate the residence time of ancient porcelain. Therefore, any scientific technique to predict both firing temperature and residence time with measurable reliability will improve archaeological ceramic dating and the understanding of manufacturing technology in ancient times.
Proposed models to determine the firing conditions
- Model #1: Glaze penetration versus firing time
- Body-glaze interaction
- WDS
- Determining the firing conditions of ancient Korean shards
- Model#2: mullite crystalline size in (110) direction versus firing conditions
- Mullite formation
- Primary mullite versus secondary mullite
- X-ray line broadening
- A broad range of firing conditions in terms of mullite crystallite size in (110)
- Model #3 silica UMF level in the glass phase versus firing conditions
- The concept of Unity Molecular Formula
- Quartz dissolution in porcelain
- A broad range of firing conditions in terms of silica UMF level in the glass
- Combination of two models to determine firing conditions
Average mullite crystallite size in the (110) direction was evaluated by collecting the full width at half maximum (FWHM) via the Debye–Scherrer equation. The silica-UMF level in the glass phase was calculated by incorporating chemical analysis results with QXRD data. The relationship between silica level in the glass phase (SiO2(G)) as a function of temperature, T (°C) and time, t (hours) was expressed by the given equation:65.
EXPERIMENTAL PROCEDURE
Chinese ancient shards
- Dating of shards
- Characterization of shards
- Chemical composition of shards
After cleaning the stains and dirt of the sherds on the surface, we measured the apparent open porosity, water absorption and bulk density of the ancient sherds using the standard boiling water test method.69. The fragments were cut into small pieces with a diamond saw (Isomet low-speed saw, Buehler, Lake Bluff, IL, USA) and mounted in epoxy, then polished with diamond compound. The body chemistry of these 18 sherds was measured by inductively coupled plasma emission spectroscopy (ICP-ES, ACME Laboratories Ltd., Vancouver, B.C.) after the glaze was removed.
Mean body chemistry scores for both WP and GWP groups are listed in Tables II and III, along with chemical compositions cited by references. The similarity between the measured and quoted chemistry appears to be another clue to support that the collected samples of WP and GWP derive from the Five Dynasties and the Song Dynasty respectively. In this work, the chemical composition of the glaze was obtained by the well-known EDXRF at the Jingdezhen Ceramic Institute.
The SiO2 to Al2O3 ratios on a UMF basis of both the WP and GWP groups are around 8 which falls well within the glossy area on Stull's map,45, 66 which is consistent with the glaze structure. The color change from white to light green is due to the presence of Fe2+ ions. Thus, the slight change in Fe level (from 0.69% in WP to 0.87% in GWP) from Table XIII is proposed to contribute to the glaze color transition.
Newly created bodies by using Chinese raw materials
- Raw materials
- Green samples preparation
- Firing apparatus
- Characterization of the fired specimens
The processing of all prepared bodies started with weighing (70% solid fill & . 30% water fraction), then ball milling for 1 hour, followed by slip casting. The experiment "Spot Check" (SC) was designed to check the validity of models by randomly creating body. Green bodies were formulated in either single different porcelain stoneware or binary formula (80% porcelain stoneware + 20% kaolin).73 The "Comparison Experiment" (CE) was implemented by mimicking previous formulas, including Lerdprom's (C-WL)65 and Colorado's ( C- VC)2 using only Chinese raw materials together with three typical Chinese commercial green bodies (CC #1, #2 and #3) recognized for Shuguang Porcelain Factory, Jingdezhen City, Jiangxi Province, China.
Firing temperatures were verified using pyrometric cones (Edward Orton Jr. Ceramic Foundation, Westerville, OH, USA). Samples were placed on an alumina substrate and fired according to different schedules as listed in Table VIII. Previous work had shown that both the UMF level of silica in the glass phase and the size of the mullite crystallites are independent of the heating rate, and thus a fixed heating rate (2.5 K/min) is used for all firing conditions.
The actual density of milled powder was measured using a pyconometer (AccuPyc 1330, Helium Pycnometer, Micromeritics Instrument Corp., Norcross, GA, USA), followed by quantitative XRD analysis (QXRD). QXRD analysis was performed using CaF2 as internal standard and analyzed by Jade (version 9, Materials Data Inc., Livermore, CA, USA), as described in detail elsewhere. 2, 65 Peak areas of three non-overlapping peaks were selected for these three mineral phases: mullite, quartz and calcium fluorite, as specifically mentioned in Table IX. In addition, the crystallite size of mullite in the (110) direction was calculated using Full Wide Half Maximum (FWHM) from X-ray diffraction patterns, as described elsewhere 63 , 65 .
RESULTS AND DISCUSSION
General observation of ancient Chinese shards
Because insufficient mixing tends to result in the isolation of quartz without contacting the glass (formed during firing), promoting cristobalite formation.63 This is consistent with historical records as stated in section 2.3.3.1, when porcelain stoneware was the only component that was manufactured body in Jingdezhen from Five Dynasties to the beginning of the Song Dynasty. Therefore, no additional mixing procedures were involved in the preparation of raw materials, resulting in the presence of larger quartz cluster in the glaze layer.
Approximate estimation of firing time
Assuming that the total wood was distributed evenly to 11 main production areas and that the kilns in Jingdezhen were of the same size. It is possible to roughly estimate the approximate firing cycle of Jingdezhen kilns during this time period. The estimated firing cycle for individual kilns in the Jingdezhen area during the Five Dynasties to the Song Dynasty is about 7 days, which includes loading, heating, staying at peak temperature, cooling, and unloading.
A reasonable length of stay would be estimated at 2 to 4 days if these procedures required one day in addition to the stay.
Three proposed models to determine the firing conditions of Chinese ancient
Evaluation of three proposed models
- Model #1: glaze penetration depth versus firing time
- Three potential conditions
- Low firing temperature
- Assumptions for Model #2 and Model #3
- Validation of glass formation boundary
- Contribution of fine particles to X-ray line broadening
- Potential correction for Model #3 silica UMF level in glass phase versus firing
However, the four regression lines in Figure 24 show the correlations between the silica level in the glass phase and the initial silica level in the body under the firing conditions (1250 °C or 1300 °C for 3.2 or 32 h). Relationship between initial SiO2 UMF in the body and SiO2 UMF in the glass phase at different firing conditions with their regression lines. The level of dissolved alumina in the glass phase was calculated using the overall chemistry to subtract the Al2O3 content of the mullite via QXRD.
Relationship between Al2O3 UMF in the glass phase and the mol% flux in body under different burning conditions. The result proposed to explain the relationship between initial SiO2 level in body and dissolved SiO2 in the glass phase, shown in Figure 24. The silica UMF level in the glass phase - comparison of previous model and experimental data of "SC" group, with initial SiO2 UMF.
The silica UMF level in the glass phase - comparison of previous model and experimental data from the "CE" group with initial SiO2 UMF. Regression analysis of measured silica in the glass phase versus predicted silica level for various bodies is shown in Figure 31. The regression analysis of measured silica in the glass phase versus predicted silica level (compared to the "WL" model).
Relationship between body available SiO2 level (corrected for mullite formation) and glass phase SiO2 level at different firing conditions with their regression lines.
SUMMARY AND CONCLUSIONS
FUTURE WORK
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Lee, “Determination of Firing Conditions of Ancient Korean Celadons (Correction for Iron Level).” during the 8th Asian Symposium on Ceramics Technology. 34; Standard Test Methods for Apparent Porosity, Water Absorption, Apparent Specific Gravity, and Bulk Density of Burned Refractory Bricks and Shapes by Boiling Water. ". The body chemical composition of white porcelain (WP) in Jingdezhen from the Five Dynasties to the Song Dynasty by ICP.
Body Chemical Composition of Greenish-White Porcelain (GWP) in Jingdezhen from the Five Dynasties to the Song Dynasty by ICP. Chemical Composition of White Porcelain (WP) Glaze in Jingdezhen from the Five Dynasties to the Song Dynasty by EDXRF. Glaze Chemical Composition of Greenish-White Porcelain (GWP) in Jingdezhen from the Five Dynasties to the Song Dynasty by EDXRF.
