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This paper employs a systematic approach to packaging design and testing of a system and its components in order to determine the long term durability of light duty diesel filters. This effort has utilized a relatively new aluminum titanate filter technology as well as an advanced support mat technology engineered to provide superior holding force at lower temperatures while maintaining its high temperature performance. Together, these two new technologies form a system that addresses the unique operating conditions of diesel engines. Key physical properties of both the filter and the mat are demonstrated through laboratory testing. The system behavior is characterized by various laboratory techniques and validation procedures.

A novel diesel particulate filter for passenger car applications was introduced by Corning, based on a stabilized aluminum titanate composition. As part of the development and material evaluation Corning has performed extensive on-road testing of the new material. The testing included several vehicles, filters, system layouts and driving profiles. The filters were tested from 100,000 km to 240,000km. All test vehicles were equipped with instrumentation and data acquisition hardware, enabling the detailed recording of the relevant parameters such as temperature profiles inside the filter, the pressure drop as well as engine data. Throughout the field evaluations the filters were regularly checked for emissions over the NEDC on a chassis dynamometer according to the current European test protocol. In all cases excellent emission performance has been observed over the duration of the tests. The pressure drop performance has generally been good.

Catalyzed soot filters are being fitted to an increasing range of diesel-powered passenger cars in Europe. While the initial applications used silicon carbide wall-flow filters, oxide-based filters are now being successfully applied. Oxide-based filters can offer performance and system cost advantages for applications involving both a catalyzed filter with a separate oxidation catalyst, and a catalyzed filter-only that incorporates all necessary catalytic oxidation functions. Advanced diesel catalyst technologies have been developed for alternative advanced oxide filter materials, including aluminum titanate and advanced cordierite. In the development of the advanced catalyzed filters, improvements were made to the filter material microstructures that were coupled with new catalyst formulations and novel coating processes that had synergistic effects to give enhanced overall performance.

Over the past decade, regulations for mobile source emissions have become more stringent thus, requiring advances in emissions systems to comply with the new standards. For the popular diesel powered passenger cars particularly in Europe, diesel particulate filters (DPFs) have been integrated to control particulate matter (PM) emissions. Corning Incorporated has developed a new proprietary aluminum titanate-based material for filter use in passenger car diesel applications. Aluminum titanate (hereafter referred to as AT) filters were launched commercially in the fall of 2005 and have been equipped on more than several hundred thousand European passenger vehicles. Due to their outstanding durability, filtration efficiency and pressure drop attributes, AT filters are an excellent fit for demanding applications in passenger cars. Extensive testing was conducted on engine to evaluate the survivability and long-term thermo-mechanical durability of AT filters.

Compositions in the mixed strontium/calcium feldspar ([Sr/Ca]O·Al2O3·2SiO2) - aluminum titanate (Al2O3·TiO2) system have been investigated as alternative materials for the diesel particulate filter (DPF) application. A key attribute of these compositions is their low coefficient of thermal expansion (CTE). Samples have been prepared with porosities of >50% having average pore sizes of between 12 and 16μm. The superior thermal shock resistance, increased resistance to ash attack, and high volumetric heat capacity of these materials, coupled with monolithic fabrication, provide certain advantages over currently available silicon carbide products. In addition, based on testing done so far aluminum titanate-based filters have demonstrated chemical durability and comparable pressure drop (both bare and catalyzed) to current, commercially available, silicon carbide products.