Alternating Plugging Process for DPF Wall-flow Substrates
A brief introduction to the alternating plugging process for DPF wall-flow substrates.
Alternating Plugging Process for DPF Wall-flow Substrates
Alternating plugging is a critical step in transforming a flow-through honeycomb ceramic into a wall-flow DPF substrate; by alternately plugging the ends of the channels, exhaust gas is forced to pass through the channel walls, thereby capturing particulate matter.
Plugging Principle
Adjacent channels are plugged at one end and left open at the other, creating an alternating checkerboard pattern:
Channels plugged at the inlet end are open at the outlet end.
Channels open at the inlet end are plugged at the outlet end.
Exhaust gas enters through channels open at the inlet end → reaches the plugged end → is forced through the channel walls → enters adjacent channels → exits through the outlet end; particulate matter is trapped during the wall-passage process.
Plugging Slurry
Component | Function | Proportion |
Carrier material powder | Same material as the carrier; ensures bonding | 50%-70% |
Binder | Enhances bonding strength | 3%-8% |
Water | Adjusts viscosity | 20%-40% |
Slurry fineness ≤10 μm; solids content 35%–45%.
Sealing Process Steps
Step | Operation | Key Parameters |
①Inlet-end protection | Cover channels to remain open; expose channels to be plugged | Alignment deviation ≤0.5 mm |
② Inlet-end plugging | Vacuum-assisted slurry filling of unprotected channels | Plugging depth: 5–15 mm |
③ Drying | Curing at 80–120°C | 2–4 hours |
④ Outlet-end plugging | Flip over and repeat steps ①–② to plug the remaining channels | Reverse checkerboard pattern |
⑤ Sintering/Curing | Sintering at 1000–1200°C | 2–4 hours |
Summary
The DPF alternating plugging process can be summarized as follows: checkerboard masking of the inlet → vacuum filling → drying → reverse plugging of the outlet → sintering and curing. Key parameters include a plugging depth of 5–15 mm, a slurry solids content of 35%–45%, and an alignment accuracy of ≤0.5 mm. Plugging depth directly affects pressure drop (increasing by 3%–5% for every 1 mm increase in depth), requiring optimization between filtration efficiency and backpressure. This process is the core technology for converting flow-through substrates into wall-flow filters.