| Ancient ceramics are indispensable cultural heritage and scientific works of art.China is the country where ceramics were invented,and various Chinese comprehensive museums and large-scale sites have rich collections.There are still countless pieces of ancient ceramics that have not been excavated and sorted out.For the detection methods of ancient ceramics and other cultural heritage,it is very important to develop a multi-faceted nondestructive evaluation method.However,based on optics,electricity and acoustics,the non-destructive,rapid and convenient detection and analysis of the basic properties of ancient ceramics is an unsolved problem in the field of ancient ceramics.This paper takes Yaozhou celadon as the main research object.Based on the theory of non-destructive testing,the optical,electrical and acoustic properties of Yaozhou celadons are detected and analyzed.The relevant data are analyzed and quantitatively classified.Then the optical,electrical and acoustic parameters of Yaozhou celadon are analyzed.Related to its structure and composition,it is expected to explore a set of nondestructive testing methods(or systems)that are suitable for non-destructive testing of ancient ceramics,including optics,electricity,and acoustics.The specific research results are as follows:(1)Based on the CIE(Commission Internationale de lEclairage)1976 La*b*uniform color space,the analysis from Color characteristics of 223 celadon specimens from seven kiln sites in China,Japan,and Korea.The color characteristics of celadon from different kiln sites were analyzed by H(hue),C(purity)and L(lightness),and the color was classified.The descriptions of celadon color are standardized,transforming celadon color from subjective sensory descriptions to objective scientific descriptions.The analysis found that the ranges of H,C,and L of celadon were:60°～180°,0～35,20～90,and the medians of H,C,and L were 105°,12.5,and 55,respectively.Blue is not included in celadon color.The C value of celadon ranges from 0 to 35,indicating that the color saturation of celadon is low.The L value of celadon color ranges from 20 to 90,which is closely related to the color of the celadon body.The L value of white body is higher,and the L value of black body is lower.(2)The difference in glaze color between the inner and outer surfaces of Yaozhou sky-green celadons,and the chromaticity difference between the concave and convex parts of decoration on the Yaozhou olive green celadons,the chromaticity data of Yaozhou celadons were calculated and analyzed respectively.This paper found that the outer glaze colors of Yaozhou sky-green glaze samples are greener,and the colors of inner glazes are more yellow.The purity of the outer glaze is higher than that of the inner glaze,and the colors are more vivid.The brightness of the outer glaze of the samples are lower than that of the inner glaze,indicating the brightness of the inner glaze is higher.In addition,the chromaticity of the decorative parts of the ancient Yaozhou olive green celadon samples was analyzed,and it was found that the glaze layer of the light-colored parts of the samples were thinner,and the average and median H values were around 90.The average and median values of C in the light-colored part of the pattern are very close to those of the decorative substrate,while the average and median values of L are about 10 lower than those of the decorative substrate,indicating that the depth of the ceramic pattern color is mainly determined by the lightness.(3)The flexible graphite electrodes were designed that can closely fit the curved surface of ancient ceramics,and the device for non-destructive measurement of the electrical properties of ancient ceramics was produced.The dielectric properties of Yaozhou celadon were measured and analyzed.The nondestructive measurement method can collect the electrical properties of various cultural relics such as ancient ceramics,and the data of the sampling points are consistent with the macro-scale of the ancient ceramics and the collected data is similar in the same kind of cultural relics.It is found that the proportion of Yaozhou celadon glaze in the Five dynasties had a significant influence on its dielectric properties and resistivity.As the glaze proportion of celadon samples increased,the dielectric constant would decrease,but the resistivity would increase.In addition,the size of the large bubbles in the glaze can reach about 0.2 mm,which is the important reason for the decrease of the dielectric constant and the increase of the resistivity.When the ratio of SiO2/Al2O3 in ancient ceramic glaze is higher,more glass phase is produced in ceramics,which is also an important factor affecting the change of dielectric constant and resistivity of ancient ceramics.(4)A non-destructive testing method for the acoustic properties of ancient ceramics in the audible frequency band(20Hz～20kHz)was designed.In this method,the gradient audio frequency of 20Hz～20kHz is used as the sound source.By comparing the original audio with the sound waves collected by the sound source after contacting Yaozhou celadon,the modal characteristics of the sound signal were extracted,and the collected acoustic data were analyzed.The acoustic waveform,frequency spectrum and frequency response of the ceramic samples were analyzed to calculate the inherent characteristics of ceramics,such as acoustic wave transmittance and resonance frequency(or resonance range).For example,it can be calculated by combining the porosity data.According to the elastic modulus of Yaozhou celadon,the origin of ancient ceramics is divided.The acoustic detection method is a useful non-destructive detection method.This method overcomes the test error caused by the local difference of the test points,and is suitable for acoustic performance testing of ancient ceramics or other cultural relics.(5)The relationship between glaze color of Yaozhou celadon and the symbiotic "flint red" color at the junction of the body and glaze was established.The formation mechanism of "flint red" and its influence on glaze color were analyzed.It is found in this paper that flint red is mainly composed of hematite.Flint red is formed by ceramics in a reducing atmosphere.As the melt moves,reduced iron deposits steam on the substrate.It is a layer of hematite film formed at the junction of the body and glaze,and the surface of the body by secondary oxidation during the cooling process of the kiln.In addition,it is also found that the position of samples in kiln will affect the formation of flint red.The chromaticity of flint red reflects the degree of oxidation and reduction of ceramics to some extent.When the H value of flint red is lower than 70,the hematite content in flint red is higher than 1.2%.As the amount of F e in the melt diffused to the body increases,more flint red will be formed,and the H of flint red on the body will decrease.Meanwhile,the H of the glaze will increase and the color of the glaze will be greener.(6)The electrical and acoustic tests were conducted on the modern Yaozhou celadon samples.The experiment shows that the ratio of glaze and the bubbles in the glaze have a significant influence on the dielectric properties and resistivity of ceramics.After the acoustic measurement of samples,the elastic modulus of the samples can be calculated according to the measured resonance frequency and other acoustic parameters.It is found that the elastic modulus of samples is exponentially related to its porosity.In addition,through the accumulation of optical,electrical and acoustic data of ancient ceramics,we can make correlation analysis on the properties of ancient ceramics,such as coloring mechanism,glaze ratio,porosity and elastic modulus.The accumulation of optical,electrical and acoustic data of ancient ceramics is of great significance to the study of ancient ceramics characterization and the establishment of its database. |
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