Raw material

Alumina

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Description

Alumina is as one of the most important ceramic oxides that has many applications in industry and engineering material. Alumina used in most cases due to high corrosion and oxidation properties at high temperature.
Impurities often reduce product life and corrosion resistance.
Key features of alumina which has caused it to be used in various applications are including: high compressive strength, high hardness, high wear resistance, high chemical resistance, high thermal conductivity, thermal shock resistance, high refractory, high dielectric strength and high electrical resistance even at high temperatures.
There are various grades of alumina. Every ceramics manufacturer, according to the needs of alumina, will use one or more grades of it. Metallurgical alumina is used in the production of aluminum metal.
If aluminum hydroxide is heated at temperature above 1100 °C, calcined alumina is produced. Calcined alumina used in a wide range of refractory applications and ceramic products. Sodium oxide is the main impurity in this type of alumina.
Reactive alumina is usually used about alumina with relatively high purity and fine crystal size. According to another definition, reactive alumina can form a body that gives high density after sintering at relatively low sintering temperature (about 1550-1650 °C). This type of alumina is obtained after crushing and grinding processes of calcined alumina. However, calcination of this type of alumina occurs at high temperatures. Percent of sodium oxide that presents in this type of alumina is carefully controlled to be as low as possible.
This type of alumina used in places that requires great strength, wear resistance, heat resistance and chemical stability. Actually this type of alumina used in produced body where the mechanical behavior at high temperature is important for us. This type of alumina is used in composites, refractories and etc.
Tabular alumina, is that sintered or recrystallization α–alumina. It is called tabular because its morphology includes large, flat and sheet form of corundum. This type of alumina is produced by precipitation, extrudes or presses of calcined alumina and then annealed at temperature below the melting point (1700-1850 °C), in rotary kiln. In some applications it can be used as catalyst bed, because these materials are sintered, resulting porosity is low. This type of alumina has good chemical stability and high refractories. Due to its characteristics is used in the production of various refractories. In fact, the most application of this alumina is production of castable and shaped refractory.  This type of alumina helps to increase body strength. Another reason for using this type of alumina is different size of particles. In addition to the said applications tabular alumina is used to make carbon-alumina composites. These composites are used in the manufacture of tundish drain valve slide.
Fused alumina is produced in an electric arc furnace. Fused alumina has a high density, low porosity, low permeability and high refractories. Because of these properties, this type of alumina is used in manufacture of abrasive and refractory. Porous alumina has a high porosity. Type of porosity in this alumina is closed. This type of alumina has low density, light weight and insulating properties and is used for insulating body similar to insulating mass. This type of alumina is produced by blowing air into the electric arc furnace.
Alumina is calcined at low temperature called active alumina. Due to the low temperature calcination, percent of other phase than α-phase are much. Because high chemical activity of non α-phases, this type of alumina has a high chemical activity and hence it is used in the manufacture of catalysts and catalyst substrate.

APA Ceram

APA Ceram group is pioneer in importing and supplying alumina with grain size and purity that have been determined by industrial units, and likewise consultation on material selection and engineering services

Ballclay

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Description

A second group of plastic material based on the importance in ceramic industry after kaolin, is ball clay. Kaolin is a primary deposition, which remains in its original place, but ball clay is a secondary deposition that is extracted from places other than their original locations. Ball clay is transported by water and wind to other places, which this transition leads to three important properties:

  1. Grain size of ball clay is smaller and with organic impurities which may cause ball clays have more shaping ability.
  2. Plasticity of ball clay is much higher than kaolin.
  3. Color of ball clay after firing due to the presence of organic and inorganic impurities more dark than kaolin.

The main reasons of ball clay use are: 1- high plasticity 2- shaping ability(formability)(hold water in itself) 3- high raw strength 4- increase fluidity of casting slurry 5- bodies with ball clay are similar to  other bodies are more compact and sintering operation is better because it has low melting temperature 6- since that ball clay has many kinds of impurities should not be used in large quantities 7- due to fine grain and low melting temperature if its amount increases causes melting temperature sharply decreases and products are deformed 9- if the amount of ball clay is high, while increases working capacity but causes severe contraction in the body and dried body is cracked with severe contraction at the end.
Some types of ball clay have fluidity properties that this feature causes them to be valuable in mold of ceramic fragments such as sanitary porcelain. Actually ball clay increases the fluidity of casting slurry, without water if we want to increase fluidity of slurry, ball clay will add to mix.
General composition of ball clay comprises 20-80% kaolinite, 10-25% mica, 6-65% silica (quartz).
Ball clay is also used as a suspending agent in glaze slurry.
Overall, in compared with kaolin, ball clay is finer grained, darker, low temperature refractory and has more plasticity, low shrinkage on drying and firing process.

APA Ceram
The second important plastic material in the ceramics industry, after than kaolin, is ballclay. Major consumptions of ballclay are in tile and sanitary ceramic industries. APA Ceram Group is active in importing and supplying of ballclay in noodles and powder form with high purity.

Barium Carbonate

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Description

Barium carbonate is a source for barium oxide. Barium oxide decreases melting temperature and glass will be denser. Barium carbonate is a suitable flux for high temperature frit, although additional barium carbonate will lead to unwanted crystallization. Barium oxide mainly can be used in optical glass and lead glass, instead of lime or red lead. Glasses containing barium are not heavy such as lead glass, but they have similar brightness due to the high refractive index. If the glaze firing is done in an oxidation atmosphere, this material may be used instead of lead oxide. Small amounts of this oxide improve the brilliance of glaze, but if amount of this oxide increases more than optimum content, it is opacifier. The glazes containing this oxide are toxic. Although barium oxide creates problems for glaze during firing, but it alters hardness and chemical stability of glaze.
The main advantage of using Barium in compared to other alkaline earth metals in frit or glaze is creation of brilliance on glaze surface. This element plays a valuable role in creating fine matte crystalline glaze. Elements such as barium oxide, titanium oxide and calcium oxide is added mainly to a combination of frit and theirs consumption in raw form is less, because a result of the thermal decomposition of calcium and barium carbonate is formation of gelly-ZnO and cracking of glaze when CO2 gas coming out.
Barium carbonate is added to clays to precipitate soluble salts in the brick, tile, and earthenware bodies.

APA Ceram
Most of barium carbonates which used in the ceramics industry are supplied from china, and APA Ceram Group takes action to import and depots of this product from the best and most reliable Chinese supplier.

Boric acid

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Description

Boric acid or borax used as raw materials in the glass and glaze industries. In glasses that require to purity and high quality color is preferred to boric acid and borax are pure. Presence of boron in glass addition to reducing thermal expansion, lead to increase the chemical durability of glass. Boric acid is the very cheap source of boron.
Boron compounds are rarely used as raw materials in glazes, but presence of this material as an ingredient in many frits is useful. During frit making, presence of boron is leading to the formation of glass in the early stages. Borosilicate composition resistance against chemical attacks is good. Glazes containing high amounts of boron are very fluid and quickly be fired. The disadvantage of this type of glaze is easily phase separation. Boron reduces the surface tension of glaze and increases the speed of smoothing glaze surface during firing. Addition of specified amounts of boron to glaze reduce thermal expansion, improve mechanical strength and resistance to scratch. Boron-containing glazes are a good base for colored glaze, which color is created through dissolve transition elements. About addition of boric acid to the frit, it should be noted that the ratio of SiO2/B2O3 is less than 1 to 2. During batches containing boric acid make frit, loss of boric acid through formed water vapor should be assessed.
APA Ceram 
APA Ceram Group, in association with the import and supply of chemical materials, which used in the ceramics and tile industries, offers imported boric acid from Turkey with the highest quality.

Carboxymethyl cellulose

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Description

Carboxymethyl cellulose is a synthetic material, which added to body and glaze for increase plasticity properties and strength. This material is completely removed during the firing process of the body and glaze and from view point of quality does not change on glaze surface. This substance dissolves quickly in cold and hot water, basically CMC to be used in cases that aim is control the viscosity, because does not form gel even in the presence of calcium ions. Carboxymethyl cellulose can be used in tile, sanitary porcelain industries as a binder and in glaze and engobe as a thickener. This material in the ceramic and tile industry is a stabilizer, preservative, absorbent of water, layer forming agent, the donor concentration and improvement agent for strength. This material improves covering ability of glaze and also improves the adhesion strength between glaze and ceramic. This matter is nontoxic, does not spoil in storage and does not have ash after firing. Carboxymethyl cellulose, depending on the type of product and production conditions, can have different deflocculant properties from low to high according to desired viscosity. CMCs with less degree of polymerization, have more defloculant properties.

APA Ceram
APA Ceram group is one of the active companies in preparation and importation of carboxymethyl cellulose. It is noteworthy that all imported carboxymethyl cellulose products by this group, has the highest quality and standard with three viscosities; low, medium and high, respectively. Also there are possibility of check and quick dispatch imported material.

Feldspar

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After clays fledspar is one of the main raw materials which used in earthen wares. Feldspars divided to three groups: calcite, sodic and potassic. Feldspar as flux is used in many ceramic products and does not have plastic property. Sodic feldspar is weaker flux than potassic feldspar. Feldspar affects on all properties of fired products such as transparency, expansion and casting properties of slurry. From view point of flexural strength, bodies containing sodic feldspar are weaker than bodies containing potassic feldspar, but thermal expansion coefficient of bodies containing sodic feldspar is higher amount. Sodic and potassic feldspars are used in the glaze, but potassic feldspar seems more appropriate for reaction with silica and formation more stable glaze. Feldspar during melting has high surface tension, so presence of too much feldspar in glaze can cause island defect in glaze. Potassic feldspar consumption amount is higher than other feldspars. About 65% of the feldspars in glass industry, 30% in ceramic industries and 5% as fillers and other items are consumed. In glass industry, feldspar is a source for required sodium and aluminum. Impurities with feldspar are often quartz, mica, iron and iron compounds and titanium oxide.
Generally, the main consumptions of feldspar are:
Flux in ceramic body and glaze
Ceramic manufacturing industry such as porcelain, tiles
Making glaze
Glass industry
Production of color

APA Ceram
India is one of the largest and the most-known geographic areas in supplying and producing of feldspar clay. India is very rich in feldspar mines and their products have many customers in all over the world. Since APA Group has an exclusive representative and partnership in India, is able to purchase and import of feldspar with constant quality and according to international standards. In addition to providing quality products, regular depots exist in store of APA Company; also presence of experienced experts of laboratory for provide some services such as consultation for the formulation is the benefits of working with the APA Ceram Group.

Zirconium Silicate

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Description

Zircon or zirconium silicate as an opacifier has the most consumption in ceramic glaze with firing temperature above 1000 ᵒC. opacity of this material is affected with other elements such as aluminum and zinc. The presence of zircon in glaze lead to increase density, resistance to cracking and chemical durability of glaze and reduction of thermal expansion coefficient. High viscosity glaze containing zircon lead to carbon stains even at high temperature. All source of zirconium contain various amounts of hafnium, and since that chemical properties of these materials are similar and the separating processes are very expensive, many grades of zirconia contains more than 3 wt% hafnium.
APA Ceram
Major applications of zircon are in the ceramic, refractory and glaze industries. APA Ceram is supplier of required zircon with high quality from well-known manufacturers.

Sodium tripolyphosphate

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Mineral salts and derivatives of Weak inorganic acids are effective dispersants in aqueous solutions. Should always be considered, if the absolute value of zeta potential increases dispersant is good. Phosphoric ions are types of ions that prefer to adhere to the clay particles and increase negative charges. In this way, the absolute value of zeta potential is also increasing. Anions can absorb obtrusive ions and form complex. The presence of sodium ions cause the zeta potential becomes more negative. Viscosity of slurry dispersed with polyphosphate, with the passage of time and increasing temperature will rise.
The most important factors in the selection of dispersant include: cost, effectiveness, and sustainability.
Generally a mixture of two or more dispersant is used in ceramics industry, for example combination sodium silicate with tripolyphosphate increases the dispersant efficiency.
Among the factors affecting on dispersion can be cited to pH, water hardness, temperature and time of milling, and ball mills spinning speed.

APA Ceram
One of the main exporters for sodium tri-polyphosphate is China. Based on statistic of Iran’s production, it seems that the light sodium tri-polyphosphate can has significant consumptions in ceramics industry. In this regard, APA Group tries to supply light sodium tri-polyphosphate granules with three density included low-, medium-, and high-density and with high quality from china and thus develop the quality of industrial societies. Beside to preparation sodium tri-polyphosphate in accordance with the certain standards, APA Ceram be able to provide services for control of quality and eliminate of industrial production lines’ defects for and the consultation from delivery step of sodium tri-polyphosphate.

Kaolin

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From view point of industries, a type of clay that contains large amount of kaolinite is called kaolin. From view of physical properties kaolin is a semi-crystalline material and somewhat amorphous. Special properties of kaolin include adhesion (which increases with increasing purity), colloidal and water absorption ability. Kaolin ore based on type of bond is divided to two group soft bond and hard bond. Kaolin with soft bond and hard bond can be used mainly in tile, ceramic industries and rubber, paper industries, respectively. Kaolin is also widely used in the refractory industry. This material contains 20 to 45 percent of alumina. In chemical and industrial conditions, kaolin in the pH range 3 to 9 may be stable, thus so easily can be used as pigments, coatings and fillers with other compounds. Among the important economic characteristics of kaolin is its particle size.
Characteristics of consumable kaolin in ceramic industry are related to impurities that may cause discoloration of the product after firing. The most important impurity is iron oxide. Other impurities can be copper, chromium and manganese. Allowable amount of Fe2O3 in ceramic is 0.6 to 0.7 percent. Iron oxide in consumable kaolin in porcelain should be less than 0.5% because iron and titanium in ceramic body will react and will reduce transparency. Potash in consumable kaolin in porcelain should be less than 1.5 percent and amounts of titanium and silica should be minimal.
Fine-grained kaolin is preferred in ceramic industry, because fine-grained kaolin increases plasticity and raw body resistance. Selection the type of grading is also very important, although small and soft kaolin reduces the degree of casting but causes contraction during firing.
To summarize the major characteristic of kaolin, which has led to its frequent consumptions can be named as followed:

From chemical view kaolin remains unchanged in a wide range of pH
Having white color
Having a good coating properties
kaolin is soft and non-abrasive
Limited ability to conduct electrical current and heat
cheap price
APA Ceram
Due to the fact that ceramic industries need to Kaolin with constant physical and chemical characteristics, and major consumptions of kaolin are in tile, sanitary ware, and refractory, glaze and color industries. APA Group attempts to be active in importing and supplying of grading kaolin with high purity and constant or uniform quality.