We are able to offer a wide variety of grades of high performance silica and silica zircon compositions that are stable at high temperatures that can be matched to Directionally Solidified (DS), Single Crystal (SX) and Equiax casting processes.
The following are some of the frequently used ceramic core materials, with details of the casting processes and situations to which each is most suited.
This material is particularly suitable for use in Equiax casting, a process in which ceramic moulds are pre-heated to a temperature just below that at which the alloy solidifies. Thus, when the alloy enters the mould, it quickly freezes and gives a uniform grain structure. Ceramic materials of >97% alumina can be used with a wide selection of alloys including those that are nickel and cobalt-based, and the ceramic takes the form of a single material with coarse particle size distribution. Ceramic materials of >97% alumina are not leachable by standard methods, but show great strength and refractory qualities.
Another ceramic ideal for use in Equiax casting, >95% zircon is particularly suited to alloys containing high levels of cobalt. Cobalt reacts with cores that contain a high proportion of silica, making silica cores unsuitable for these applications. Ceramics that are >95% zircon have a coarse particle size and are suitable for the casting of large, chunky parts. They are non-reactive and not leachable by standard methods so must be removed mechanically or via water blasting.
Ceramics of >94% zirconia are used mainly in Equiax casting and give excellent results when used with titanium alloys. They have a fine particle size and must be removed by knock out, sand blast or water jet.
100% fused silica
Another ceramic mainly used in Equiax casting, fused silica is good for use with most nickel and aluminium alloys. Fused silica ceramics are available with various particle size distributions, to permit the manufacture of a range of geometries, and they are highly leachable, including by water jet removal. Fused silica is stable, weak and crushable, and is resistant to hot tearing.
96% fused silica, 2% zircon, 2% alumina
This combination forms a ceramic material that is most often used in directionally solidified and single crystal casting, and with most DS and SX alloys. The combination of 96% fused silica, 2% zircon, 2% alumina is available in a range of forms, but generally has a fine particle size for use in the casting of small, complex parts. It is highly leachable and as such it is ideal for casting blind passageways and in small, intricate cores. This ceramic material shows great stability at high temperatures.
74% fused silica, 24% zircon, 2% alumina
The highly versatile blend of 74% fused silica, 24% zircon and 2% alumina can be used in Equiax, directionally solidified or single crystal casting, and with alloys that have high temperature pre-heats. It is often used with most nickel-based, DS and SX alloys. Available with various particle size distributions, it can thus be used in the manufacture of a range of geometries and shows good leachability. The combination of 74% fused silica, 24% zircon, 2% alumina shows excellent stability at high temperatures and can be used in a wide range of core sizes and designs.
There are more compositions available to fit the customer requirements. All materials and their respective properties and compositions can be viewed within the datasheets section.
If you would like to know more about how our different grades of silica zircon are used in our ceramic cores, please contact us today.