15 - Ceramic filter for trapping diesel particles

Abstract

This chapter describes the basic properties and characteristics of a ceramic filter with a porous silicon carbide obtained by a recrystallization method, which is used for trapping diesel particles. Several basic study items applied in the testing of the filter medium in the Diesel Particulate Filter (DPF) for trapping efficiency, pressure loss, strength, and heat resistance are presented. The production of particulate matter (PM) involves three processes, where the first is the PAH (Polycyclic Aromatic Hydrocarbon) production process, another process is the one where the PAH grows into crystallites of soot, and finally another one in which PAH aggregates into soot. The soot discharged from diesel engine vehicles is a product of aggregation of crystallites of about 1.4 nm in size and the SMPS (Scanning Mobility Particle Sizer) is used here for measuring the PM. Silicon carbide provides a high coefficient of thermal conductivity among the ceramics and a recrystallized porous silicon carbide has a very small shrinkage of 1% or less in the burning process, which makes it much easier to control the dimensions during manufacture. The function of DPF is to purify gas emissions by trapping PM through filtration and the requirements for its PM trapping efficiency and low pressure loss are provided by a porous structure obtained from the properties of recrystallized silicon carbide. The development of a filter based on the characteristics of silicon carbide is able to trap nanoparticles in the diesel particles with a trapping efficiency of almost 100%.