European Exhaust and Catalyst
European Exhaust and Catalyst
Discussing ceramic DPF substrates – SIC vs cordierite
Published on: 18/02/2016

Diesel engines produce large amounts of particulate matter, or soot, as a by-product of combustion, and require diesel particulate filters (DPFs) as part of the exhaust system. DPFs filter the diesel vehicle’s exhaust gases to remove the soot, and therefore reduce the harmful elements of exhaust gases being released into the atmosphere. DPFs contain ceramic substrates to filter and capture the undesirable elements of the diesel engine exhaust gases, and there are several different types of substrate – today we are looking at SIC (silicon carbide) or cordierite. This short article aims to help you understand the key properties of ceramic substrates and shows which of the two mentioned above performs best.

SIC has several technical advantages over cordierite that mean it is the obvious choice for a reliable and efficient DPF. It has better filtration efficiency (more than 99%) than cordierite, and has a more uniform structure, meaning it captures soot more evenly which can aid DPF regeneration. A higher mechanical strength, higher chemical stability, higher thermal shock resistance and higher thermal conductivity all mean SIC can withstand the stresses of manufacture far better, and therefore make it flexible and suitable for all shapes and sizes of DPF.

Both SIC and cordierite have excellent regenerative properties, a key advantage as DPFs need to regenerate in order to keep functioning properly. This is achieved when the vehicle has been running long enough and at a high enough speed to raises the temperature of the engine, and therefore the exhaust fumes, enabling the captured soot in the DPF to be burnt off. However the lower melting point of cordierite (it is heat resistant to 1430 degrees centigrade versus SIC’s 2200) can mean there is a risk of the component melting during DPF regeneration. Cordierite is also more susceptible to thermal crack due to sudden changes in exhaust temperature and damage due to over-sooting. SIC’s technical properties, as mentioned above, mean it is the reliable choice that outperforms cordierite in this instance.