Cerex is a supplier of high quality refractory shapes, specialising in crucibles and refractory systems for induction furnaces with capacities ranging from 1kg to 3000kg.
The special shapes and the crucibles are available in a variety of materials, including fused silica, alumina, magnesia and zirconia. These are to suit the melting and casting of steels, non-ferrous metals, superalloys and precious metals in any atmosphere.
The stringent specifications required of superalloy castings for aerospace turbines, land turbines and medical implants impose strict requirements on the refractories used for molten metal contact. Despite the use of filters during casting, chemical reaction and erosion of the refractory needs be minimised.
The least reactive oxide material for the containing crucible is zirconia. Its unique (non-) wetting characteristics make it especially suitable, but it does need a high degree of solid-state sintering during manufacture to take advantage of this.
Magnesia has been found to offer good resistance to the Ni-based and Co-based alloys melted. It has a shorter service life than zirconia but is notably cheaper per unit crucible.
Crucibles up to 220mm in diameter are normally made by isostatic pressing. This method confers uniform density throughout the length of the crucible and through its’ walls. This eliminates problems from differential density variations which can occur in crucibles made by standard, end-to-end hydraulic pressing.
The method involves lowering the ceramic mix contained in a crucible mould into a chamber; liquid is pumped in until pressures of 10,000 to 15,000 psi (70 to 105 MPa) are reached. The released crucibles are fired at temperatures between 1500oCand 1750oC.
.A wide range of material types are available, differing in their ability to withstand particular chemical environments and balance physical erosion resistance with thermal shock resistance.
沪公网安备 31011402005139号
