Printing technology of the most popular daily life

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Daily life substrate printing technology

(Qian Junhao)

1. Ceramic materials and color glaze

China's ceramic industry has an ancient and long history. Ceramics not only plays the role of packaging container, but also is a kind of widely used packaging container with national characteristics. Moreover, ceramics itself is an exquisite handicraft, which still has the value of appreciation and preservation after its contents are used. Therefore, until now, the production and surface decoration technology of ceramics is still a new technical discipline worthy of study

the raw materials for making ceramics mainly include clay (kaolin), flint or quartz, feldspar. The properties of its ceramic products depend on the quality of raw materials and the proportion of clay, quartz and flux (feldspar). The general composition is: Clay accounts for 50%, quartz accounts for 25%, feldspar accounts for 25%

ceramic glaze is the surface of ceramic body. Next, let's take a look at the history of material testing machine. Although the thickness is only a few tenths of a millimeter, it plays an important role in improving the artistic value of ceramic products and the service performance of ceramic products

the main purposes of glaze application on the body are as follows:

① make the body impervious to liquids and gases

② cover the surface of the green body, act as a covering layer, give people a beautiful feeling, and improve the strength at the same time

③ prevent contamination of the green body. Even if it is contaminated, it is easy to clean it with detergent

④ acts with the green body to make the glaze and green body become a whole

glaze has all the physical and chemical properties inherent in glass: it is smooth and bright, with great hardness, and can resist the erosion of acid and alkali (except hydrofluoric acid and hot strong alkali); The change from solid to liquid or vice versa is a gradual process without obvious melting point. The difference between glaze and glass is that it is not only silicate, but also borate or phosphate

the chemical composition of the glaze is similar to that of glass. It is a silicate solution formed by acidic oxides such as silica and boric acid and alkaline substances such as lead oxide, lime, bauxite and potassium carbonate (sodium). The composition of various glazes is shown in the table

table the composition of various glazes

the type composition of glazes the type composition of glazes soft

hard lead silicate, bauxite, lime, potassium salt

potassium silicate, lime, bauxite and other enamel glazes add 10% devitrification agent

(tin oxide, antimony oxide, fluorite, calcium phosphate, etc.)

soft glaze is transparent and low melting point, which is mainly used in pottery; Hard glaze has transparent color and high melting point, which is mainly used for ceramic ware. Enamel glaze makes hard become gelatinous and opaque (opaque), which is mainly used for enamel utensils

(I) basic reasons for the coloring of ceramic glaze

different coloring substances in the glaze have different degrees of reflection and absorption of light waves of different wavelengths in visible light, resulting in different colors of the glaze. For example, after adding different coloring substances to PBO · SiO2 glaze, the reflection curve measured by spectrophotometer is shown in the figure

ceramic pigments use different colors emitted by various metal compounds as pigments. The color of some salts is caused by the selective absorption of light by one of the ions. Ion energy absorbs light energy in three cases:

① the whole atom vibrates and is absorbed in the infrared region

② electron vibration, absorbed in the ultraviolet region

③ electrons jump between orbits and absorb in the visible light region

the last type of energy absorption is most closely related to glaze color

in the periodic table of elements, not all the ions of elements have an electronic arrangement that absorbs energy in the mailable region. Only the elements with incomplete electronic layer structure, such as transition elements and rare earth elements, can absorb ions and make the glaze appear apparent color

the distribution of coloring elements in the periodic table of elements is shown in the table

the position of coloring elements in the periodic table

Ⅰ Ⅱ Ⅲ ⅣⅤⅥⅦⅧ Li ○ beb ○ CNO ○ FNA ○ mg ○ al ○ Si ○ P △ SCLK ○ Cu □ Ca ○ Zn ○ scgati □ gevas △ Cr □ se □ Mn □ BRFE □ co

□ Ni □ rbag □ SRCD □ yinzr △ Sn △ the sustainable development of Chinese agriculture is related to global NBSB □ Mo □ teiru RH PDC.Sau □ bahglatlcepb ○ Tabi ○ w □ OS IR □ PTU □ note: ○ colorless glaze; □ colored glaze; △ devitrification glaze

a coloring ion does not always show the same color, because the frequency of electronic vibration is affected by the environment. The color generated by any element depends on its atomic valence and ion coordination number in the formation of a specific crystal, the chemical composition of the raw materials used in the glaze, and other factors (firing temperature, flame properties, etc.) will affect the final iron formed during firing. Positive divalent iron ion (fe2+) is green or cyan. Another example is that positive divalent chromium ion (cr2+) makes the glaze yellow or brown, while positive trivalent chromium ion (cr3+) makes the glaze green. In another case, (cr3+) can make the glaze red

from the point of view of crystalline chemistry, colored elements with high coordination numbers show the color of long wave light lines. Nickel (Ni) makes the sodium glaze brown and the potassium glaze bright Dacron purple; The coordination number of Ni in the former is 6, and that of Ni in the latter is 4. Manganese (MN) varies from rose to purple with glaze composition

the above example shows that although metal coloring elements and colorants are the same element, they can show different colors under different circumstances due to different atomic valence and coordination number

the hair color changes of several coloring elements are as follows:

cobalt -- blue, blue, red chromium -- yellow, green, blue, red black

nickel -- brown, blue, purple, gray gold -- carmine, rose red

copper -- green, red, cyan antimony -- yellow, gray

iron -- blue, red, brown, yellow, Tan praseodymium -- yellow

uranium -- yellow, black

the hair color and hue changes of various coloring elements and colorants are very complex. In order to fully display a certain hue, it must be controlled from all aspects. Usually, one or more coloring elements are made into pigments. The composition and crystal structure of various additives in pigments (such as parent minerals, mineralizers, fluxes, etc.) have a special impact on their colors. The firing temperature, time, flame property, composition of green glaze, particle fineness and operation method of pigment also have an important influence on the change of color

the coloring of glaze depends on the nature of colorant in glaze and the chemical composition of glaze. The coloring of the same colorant is related to the reaction category of the main machine of the dynamic stiffness testing machine adopting the 4-column frame structure

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