Extrusion, Ceramic

Vacuum Hot Extrusion of Ceramic Materials

THE CERAMEXT PROCESS

Description of the Present State of the Art
The Ceramext process is a proprietary method generally based on vacuum extrusion at elevated temperatures. While conventional ceramic extrusion processes are based on plasticity developed from the use of wet clay at ambient temperatures, the Ceramext extrusion process derives plasticity by the formation of a liquid phase in the material at high temperature. It can therefore utilize a very wide variety of raw materials, including those that would otherwise be considered waste materials, such as coal fly ash and incinerated garbage ash, which would otherwise have to be placed in expensive landfills.

Some of the important characteristics and advantages of the Ceramext process include:

* Demonstrated Use of a Wide Variety of Raw Materials
These have included many different coal, lignite, and biomass fly ash materials, low-grade clay-bearing materials, conventional ceramic bodies, mica-bearing schists, mine tailings, garbage ash, and others. In most cases, no fluxing additives have been needed, but they are available for use if required.
* A Virtually One-Step Process
The raw material is fed into the extruder, heated within it to a plastic state, and extruded through a shaped die. The only secondary processes required include cutting, post-extrusion forming if needed (such as pressing an embossed design into the surface), glazing if desired, and controlled cooling. Conventional ceramic processing requires many separate steps, such as wet extrusion and pressing, (or alternatively spray drying and dry pressing), drying, glazing, and firing.
* Superior Mechanical Properties
Tests demonstrate modulus of rupture (MOR) values in excess of 10,000 pounds per square inch (psi), which is higher than conventional ceramic tile and related products. MOR is a measure of mechanical strength in bending. Structural clay products typically exhibit MOR values on 3500-4500 psi. The same ceramic body composition processed via the Ceramext method exhibited MOR values in the 5000-6000 psi range.
* Lower Energy Consumption During Manufacturing
Processing generally occurs at somewhat lower temperatures. No energy-intensive drying is needed. One-step processing lowers auxiliary power needs.
* Impervious, Non-Porous Products
Due to the vacuum extrusion process, porosity is more easily eliminated, giving materials with better strength and no water absorption. Ceramext products will thus exhibit superior freeze-thaw performance, an important attribute for products used outdoors in freezing climates.
* Wide Range of Body Colors
Product color can be controlled by processing conditions, chemistry, and coloring additives. Colors routinely attained range from adobe to brown to reddish brown to light gray to gray to black.

PATENT INFORMATION
A patent was issued on April 15, 2003 for the Ceramext apparatus and the Ceramext method is patent pending. The application for the trademark, CERAMEXT, has been filed in the U.S.

CERAMEXT