Aluminum titanate-mullite ceramic articles

DETAILED DESCRIPTION We claim: 1.
A sintered ceramic article containing aluminum titanate and mullite as the predominant crystal phases and which is characterized by grain boundary and intracrystalline microcracking, said article exhibiting high refractoriness, excellent thermal shock resistance, a coefficient of thermal expansion (R.
T.
-1000.
degree.
C) less than 25.
times.
10.
sup.
-7 /.
degree.
C.
when sintered at temperatures of 1400.
degree.
C.
and higher, a modulus of rupture greater than 2500 psi when sintered at 1400.
degree.
C.
and greater than 5000 psi when sintered at 1500.
degree.
C.
, and having a composition bounded by Points I, J, K, L, M, I of the drawing.
2.
A sintered ceramic article according to claim 1 also containing in weight percent 0.
5-5% Fe.
sub.
2 O.
sub.
3 and/or 0.
5-5% of at least one rare earth metal oxide.
3.
A sintered ceramic article according to claim 2 wherein said rare earth metal oxide is selected from the group of La.
sub.
2 O.
sub.
3 and Nd.
sub.
2 O.
sub.
3.




Description:
BACKGROUND OF THE INVENTION Ceramic honeycomb structures composed of a multitude of cells or passages separated by thin walls running parallel to the longitudinal axis of the structure with, in some instances, discontinuities designed to extend transversely through those walls are well known to the art.
Such articles have been employed extensively as filters for fluids and as heat exchangers.
More recently, the walls of those structures have been coated with a catalyst capable of converting noxious fumes from the discharge gases of internal combustion engines and wood stoves into non-noxious components.
As can readily be appreciated, the environment inherent in those recent applications demands that the structures exhibit a complex matrix of chemical and physical properties.
For example, the mechanical strength of the structure must be sufficient to withstand the mechanical forces encountered in mounting the structure plus the physical vibrations and pressures of the emission gases experienced in use along with high refractoriness, high thermal shock resistance, low thermal expansion, and good resistance to physical abrasion from particles in the emission gases and to chemical attack from the fumes therein