Improvement of Adtech ceramic foam filters
Along with the development of science and technology, the industrial aluminum manufacturer has higher and higher requirements for the purity and quality of aluminum and its alloy materials, but the traditional refining and degassing process cannot remove the fine and suspended non-metallic inclusions in melted aluminum. Therefore, many purification methods have been studied according to their mechanism and form, which can be divided into adsorption purification, physical purification, and filtration purification. Filtration and purification are to make the metal liquid flow through a certain medium, which captures the inclusions according to a certain mechanism and purifies the metal. In 1978, the new filter --- ceramic foam filters developed by the United States provides a high-efficiency filter for the production of cast aluminum parts and is widely used in the production of semi-continuous ingots and molded castings.
The ceramic foam filter (also called CFF filter, and foam ceramic filer) is the use of polyurethane foam as a carrier to immerse it in a coating made of ceramic powder(also called alumina powder), binder, sintering agent, suspension agent, etc. And then squeeze off the excess paint so that the ceramic coating is uniformly coated on the carrier skeleton into a blank and then the body is dried and roasted at high temperature [3 ~ 10]. Foam ceramic filter is divided into bonding type and sintering type: the former relies on the binder to bond the ceramic fine particles together; The latter relies on thermal insulation at high temperatures to make the purer ceramic fine particles sintered and fused. The unique three-dimensional connected curved pore mesh skeleton structure of the foam ceramic filter makes it have a pore rate of up to 80%-90% of the open air and can efficiently filter out the large inclusions in the metal liquid and most of the tiny suspended inclusions as small as tens of microns through three filtration purification mechanisms, namely mechanical interception, rectified scum and deep adsorption.
In the past two decades, through the efforts of many domestic casting workers and researchers, ceramic foam filters and their applications in the field of liquid casting alloy filtering have been greatly developed. However, there are still characteristics such as low strength and poor thermal corrosion resistance. This article prepares a high-strength, high-pass porosity alumina matrix foam ceramic filter by optimizing the design of the ceramic raw material formulation.