Synthesis and properties of in situ layered and graded aluminium titanate/alumina composites

A novel route to simple processing of an in situ layered and graded aluminum titanate (AT)/alumina composite is described. This process offers a simple means of tailoring the composition and microstructure of ceramic materials. The processing involves partial infiltration of a porous alumina preform with titanium ethoxide to yield a homogeneous surface layer of alumina and a heterogeneous graded layer of AT/alumina. Analysis of the graded layer by X-ray diffraction shows the existence of concentration gradients, the AT content decreasing with depth. Depth profiling of the graded layer also shows gradual changes in elastic modulus, thermal expansion coefficient, and microhardness. This novel process has the potential to fabricate other material systems and architectures.