Expansion reduction of cordierite
AssigneeCorning Incorporated
InventorsEdward A. Bush, Rodney I. Frost
Life of this patent
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Abstract
A reduced coefficient of thermal expansion and an increased resistance to thermal shock in cordierite-containing ceramic articles is achieved by contacting such articles with water either in a liquid or gaseous state. It is particularly desirable for such treatment to reduce the coefficient of thermal expansion of the article by at least 1.times.10.sup.-7 .degree. C..sup.-1, measured between 25.degree. and 800.degree. C., during the contacting. This treatment can be used in conjunction with extruded honeycomb structures conventionally used as diesel particle filters and supports for catalysts which treat automotive exhaust gases.
Claims20
A process of reducing a ceramic article's coefficient of thermal expansion comprising:
- providing an anisotropic, polycrystalline sintered ceramic article having cordierite as its primary phase and an oxide composition comprising 9-20 wt. % MgO, 30-50 wt. % Al.sub.2 O.sub.3, and 41-56.6 wt. % SiO.sub.2 and
- contacting the ceramic article either with liquid water under time and temperature conditions effective to reduce the article's coefficient of thermal expansion, measured between 25.degree. and 800.degree. C., by at least 1.times.10.sup.-7 .degree. C..sup.-1 during said contacting or with water vapor at a temperature of 50.degree.-200.degree. C. and at a relative humidity of 60% or greater to reduce the article's coefficient of thermal expansion, measured between 25.degree. C. and 800.degree. C., by at least 1.times.10.sup.-7 .degree. C..sup.-1 during said contacting.
Dependencies are inferred from the claim text.