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Zircopax

Zirconium Silicate

OxideAnalysisFormula
SiO232.79%1.000
ZrO267.21%1.000
Oxide Weight183.34
Formula Weight183.34
Enter the formula and formula weight directly into the Insight MDT dialog (since it records materials as formulas).
Enter the analysis into an Insight recipe and enter the LOI using Override Calculated LOI (in the Calc menu). It will calculate the formula.
MLPT - Melting Point (MP) 2550C

Zircopax is a generic brand name of zirconium silicate or zircon (see Zircon for more information). Zirconium prices are have increased rapidly in recent years, reflecting the world supply situation.

It is often used for semi-opaqueness (finer grained materials like Superpax provide more opacity). In North America, the most popular zirconium opacifiers fall under the brand names of Zircopax Plus, Superpax, Zircosil and Excelopax. These vary according to particle size, the finer the size the greater the scattering of light (and thus the better the opacification). In addition, the finer sized materials contain a little extra silica for maximum whiteness.

Of course, the amount of zircopax in a glaze determines the opacity. Small amounts (1-3%) may give no noticeable difference but are sometimes employed to improve glaze hardness. Since zircopax is refractory, the more that is added the more the degree of glaze melting is going to be affected. Up to 15% or more might be needed to fully opacify a glaze. If higher amounts are needed the glaze formulation may need to be adjusted to reduce the amount of SiO2 or increase flux (to melt the glaze better).

Zircopax affects glaze melt viscosity, surface smoothness, thermal expansion and color development and can be implicated in a range of glazes faults associated with these. Please read the page on zircon for more information.

Even though the material is very expensive, Zircopax is added to the body recipe of “porcellanato” tiles. It is a very effective body whitener, especially for casting porcelain. Excessive additions give the porcelain an artificial "white plastic" appearance.

Typical Properties:

Formula: ZrSio4 Weight: 183.1
Linear Coefficient of Expansion (25-700C cm/cm/degreeC): 42 x 10 -7
Specific gravity: 4.5

Particle Size: Zircopax Superpax Excelopax
Microns, Ave. 1.3 .74 .55
Bulk density lbs/cu ft 100 75 75
Surface area, m2/g 4.5 9.8 12.8


Mechanisms

Out Bound Links

In Bound Links


Pictures
An example of G2571A cone 10R matte with 10% added zircopax (right). The zircopax version is very bright white compared to the original.

Click for 512% larger


By Tony Hansen

XML for Import into INSIGHT

<?xml version="1.0" encoding="UTF-8"?> <material name="Zircopax" descrip="Zirconium Silicate" searchkey="" loi="0.00" casnumber="366497-20-3"> <oxides> <oxide symbol="SiO2" name="Silicon Dioxide, Silica" status="" percent="32.790" tolerance=""/> <oxide symbol="ZrO2" name="Zirconium Dioxide" status="U" percent="67.210" tolerance=""/> </oxides> </material>


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