Chrome oxide:

In the firing from 1040C to 1165C, 2% to 5% of the amount is green in lead-free or lead-free glazes, and in low-temperature firing of about 870C, glaze is high in lead-containing amounts. In the case of red, tin oxide in the glaze also generates pink, dark green, brown, etc.

Alumina

Alumina (Al2O3, Alumina) Glazed Al2O3 components, generally taken from feldspar or kaolin. Generally, the single alumina raw material is added for special physical properties such as wear resistance, high temperature, and increased melt viscosity. Alumina can be made from bauxite γAl2O3, due to loose lattice, small bulk density, the specific gravity is also small, about 3.42 ~ 3.62. At a certain temperature, it will change to very stable α-Al2O3. α-Al2O3, also known as corundum, is the most stable among alumina crystal forms and has a high melting point (2040°C), high hardness (Mohs of 9°), and high specific gravity (3.92 to 4.0). The main role is to adjust the melting temperature of the glaze, strengthen the degree of bonding of the blank glaze and increase the high temperature viscosity of the glaze. If the amount of glazing is too much, it is easy to produce cracking, bald glaze, heap glaze and glazed porous phenomenon.

Silicon oxide

The basic composition of the glaze, commonly used silica is quartz, in the glaze to increase the melting temperature, increase the melting temperature range, reduce the flow of glaze, increase the high temperature viscosity of the glaze, reduce the coefficient of thermal expansion, increase the glaze The role of surface hardness.

Boron oxide:

Low-temperature glaze and ceramic pigments are the main raw materials. Both boric acid and borax are soluble in water, so it is best to use them as glazes before use.

Borax

Borax (Na20?B203?10H2O). Borax is a water-soluble borate that is preferably used as a frit for glazes. The borax was heated to 60°C and dehydrated into borax pentahydrate. The borax was dihydrated at 90°C, and the borax was converted into water at 130°C. The entire crystal water was lost at 350-460°C and became anhydrous borax. Heat to 741°C to melt into a clear glass. The molten borax easily melts the heavy metal oxides. The reaction with copper oxide is blue, it is green with chromium oxide, it is purple with manganese oxide, and it is brown with iron oxide. Because borax fluxing and assisting hair color are very good, borax is one of the main raw materials for glazes.

Boric acid

The use of borax will introduce Na2O. If you want to reduce the sodium content in the glaze, you can use sodium-free boric acid instead. Boric acid (H3BO3)

100°C 160°C 300°C 450°C

H3B03 → HB02 → H2B4O7 → B203 → Boron glass

Boric acid Boric acid Boric acid Boric anhydride

Magnesium oxide

In the high temperature can increase the glaze melting temperature range, but also in the flame when the glaze can increase the whiteness and can play a role in preventing glaze cracking. The calcium in the art glaze is also taken from limestone, ashes, and the like. Magnesium oxide components are taken from fossils, dolomite and the like.

Lead oxide

Lead Oxide (Pb3O4, Lead Oxide) Common lead oxides include red lead (Pb3O4), mesogen (PbO) and lead dioxide (PbO2). The red glaze is most commonly used as a raw material for pottery glazes. Its structure is as follows: Pb3O4 is decomposed at about 500°C to become PbO. If we use dense mortar as raw material, when the glaze is to be fired, the furnace can easily be reduced to gray and black metal lead under the reducing atmosphere with insufficient oxygen in the furnace. The most commonly used flux in 2PbO+C→2Pb+CO2 glazes is the main raw material for low temperature glazes. Due to the toxicity of lead, it should not be used on toys, tableware, and daily-use porcelain.

Calcium Oxide

In the glaze with high silica content, the viscosity at the time of melting can be reduced, the flowability and gloss of the glaze can be increased, the binding force of the blank glaze can be enhanced, and the phenomenon of bald glaze can be prevented.

Tin oxide

Is a good opacifying agent, if you do not add color material, add 10% in the glaze will produce opaque white, if you add other pigments will produce opaque other color glaze, mainly used in flower glaze and opal glaze Production.

zirconium dioxide: 

Is a good opacifying agent, adding 10% to 20% in the glaze can produce white opaque glaze.

Zinc oxide

Zinc oxide (ZnO3, Zinc Oxide) zinc oxide can be obtained by directly heating and oxidizing zinc metal. It is a white powder with a molecular weight of 81.4 and a specific gravity of 5.6. In the glaze, zinc oxide helps to melt, reduce swelling, prevent chapping, increase luster and whiteness, widen the firing temperature range, prevent eggshell surface and other advantages. When ZnO replaces a part of CaO, it can prevent the volatilization of lead, because too much CaO will grab SiO2 and leave volatile PbO. Calcined zinc oxide has high density, good flow of the glaze slurry, and reduces pre-firing of the glaze. Prevents glaze shrinkage.

Yttrium oxide

Antimony oxide (Sb2O3, Antimony Oxide) glaze raw materials can use antimony oxide or sodium antimonate (NaSbO3) as a whitening glaze cream agent. In the high-temperature oxidation atmosphere, almost all oxidized to non-toxic Sb2O5. The base glaze can be replaced with cobalt oxide, niobium, nickel, made of white ground glaze (Ground Coat Frits). The yttrium oxide and lead oxide can be used to synthesize yellow tintectin colorants, ie, Nepal Yellow.

Ceria

Cerium oxide (CeO2) is used as an opacifying agent in glazes, but it is not commonly used because of its high price. Antimony oxide (Pr6O11) is used in color enamels to obtain bright yellow and dark yellow enamel. Niobium oxide (Nd2O3) is added to the glaze to obtain purple, reddish purple in the sunlight, purple in the fluorescent light will have a blue tone, and purple will bring pink in the light of tungsten light. La2O3 is used in low diffusion, high refractive index optical glass fibers. Y2O3 is introduced into Sialon ceramics and its room temperature flexural strength is up to 1300 MPa.

Titanium oxide

Titanium dioxide (TiO2, Titanium 0xide) is made from natural mineral “ilmenite” (FeTiO2) and made of TiO(OH)2 colloid by sulfuric acid hydrolysis method. It is then calcined and is commonly known as titanium dioxide. Titanium oxide has a high refractive index and is the most important emulsion agent in enamel glazes. The anatase type will change to a yellow stable and irreversible rutile type at temperatures above 900°C. Because the firing temperature of ceramic glaze is more than 1000°C, titanium oxide is rarely used as an opacifier. The firing temperature of enamel glaze is mostly below 850°C, so "titanium white glaze" is the glaze that is used most frequently and has the best effect.

Titanium dioxide

 

Is the main raw material for the production of color glaze and crystal glaze, the amount of 5% to 10% will produce a matt glaze and will also produce crystal grains. It is also a good opacifier. Titanium dioxide is the most harmful impurity in ceramic white glazes.