The Effect Of High Energy Ball Milling On The Physicochemical Properties,Color Characteristics And Thermal Stability Of Mineral Pigments

Natural mineral pigments have a long history and occupy an important role in the heritage of the world’s cultures.They are chemically stable and have retained their vibrant colors after thousands of years.Their color is also extremely changeable.Excellent painters can use them to draw paintings with a unique charm.However,the market shrinks because they are expensive and complicated to obtain and apply.For the inheritance and development of Chinese silk painting,the effect of high energy ball milling on the physicochemical properties,color characteristics,and thermal stability of mineral pigments are studied,with malachite,turquoise,and lazurite as examples in this paper.The main research contents are as follows:Three mineral samples were modified using a chalking machine and a planetary ball mill.The particle size,BET performance,and morphology of modified mineral pigments were analyzed with a laser particle size analyzer,digital single lens reflex camera,scanning electron microscope,and surface area porosity analyzer.The chemical composition and crystal structure of the modified mineral pigments were analyzed with X-ray diffraction spectroscopy,transmission electron microscopy,infrared spectroscopy,and X-ray photoelectron spectroscopy.After ball milling,the color of the samples changed from bright to dark;the particles became smaller and began to agglomerate;the particle size distribution became uniform;the reactivity increased but the adsorption characteristics remained the same;the crystalline state changed differently with milling time,but the chemical composition did not change significantly.Pigment samples were prepared using PDMS method and analyzed with the CIE Lab color space model.For malachite samples,the reflectance decreased,there was a red shift after ball milling,and the color difference was affected by the milling time.For turquoise samples,the brightness and reflectance increased,and there was a green shift and a blue shift.For lazurite samples,the reflectance increased,the shape of the reflection curve changed;a green shift occurred in the early stage of ball milling,and a yellow shift occurred in the later stage.The thermogravimetric analysis was used to clarify that the thermal stability of three pigments was not affected by ball milling significantly at room temperature,but they were decomposed partially under high temperature.The pigments and gelatin were mixed and coated onto the silk to obtain the samples for the aging test.The aging samples were analyzed by the CIE Lab and CIE XYZ color space models using a high-temperature aging tester.The samples were less affected by aging,and the color darkened with the aging time.Through this study,we obtained the structural and performance changes of the milled malachite,turquoise,and lazurite pigments,which can provide some reference for the researches on the production and application of traditional mineral pigments by the ball milling method.