Coated honeycomb body and method for producing a coated honeycomb body
View Patent ↗A method for producing a metallic honeycomb body from metallic layers with channels through which an exhaust gas stream can flow, includes providing the honeycomb body with a coating. Such honeycomb bodies are used in exhaust gas systems of preferably mobile internal combustion engines as catalyst carrier bodies, filters, mixers and/or adsorbers. The coating is provided in a two-stage application and enables the production of exceptionally advantageous coated metallic honeycomb bodies, which are distinguished by a large coating surface and a low flow resistance. At the same time, an exceptionally large surface enlargement is provided in the honeycomb body while using a smaller amount of coating. A honeycomb body is also provided.
1. A method for producing a metallic honeycomb body with a coating, the method comprising the following steps:
a) providing at least one at least partially corrugated metallic layer;
b) coating at least one said metallic layer with a first coating being a washcoat, while leaving partial areas of the at least one metallic layer bare;
c) subsequent to step b), configuring the at least one metallic layer to form a honeycomb structure with channels and contact points produced between the bare partial areas of the at least one metallic layer; and
d) forming material joints at least at some of the contact points to form the honeycomb body.
2. The method according to claim 1 , which further comprises carrying out finishing of the honeycomb body after step d) in a step e).
3. The method according to claim 1 , which further comprises coating the honeycomb body with a second coating after step d) in a step e).
4. The method according to claim 3 , which further comprises carrying out step e) by providing all exposed surface areas of the at least one metallic layer in the honeycomb body with the coating, at least in a partial volume of the honeycomb body.
5. The method according to claim 1 , which further comprises applying a washcoat in a step e) subsequent to step d).
6. The method according to claim 1 , which further comprises applying an amount of coating to the at least one metallic layer, during the coating with the first coating in step b), to provide 100 to 250 grams of coating per liter of honeycomb body volume in the honeycomb body after step b).
7. The method according to claim 3 , which further comprises introducing an amount of coating into the honeycomb body, during the coating with the second coating in step e), to increase the amount of coating in the honeycomb body by 20 to 50 grams per liter of honeycomb body volume.
8. The method according to claim 1 , which further comprises:
providing at least one smooth metallic nonwoven and at least one corrugated metal foil in step a);
forming at least one stack of layers alternately having the at least one smooth nonwoven and the at least one corrugated metal foil before step c); and
then winding or twisting the at least one stack in step c).
9. A honeycomb body, comprising:
at least one at least partially corrugated metallic layer being at least twisted, wound or stacked;
said at least one metallic layer having contact points and material joints;
said at least one metallic layer having channel walls, said channel walls defining wedges at said contact points;
said channel walls having a coating with a first coating thickness at said wedges transitioning to a second coating thickness adjacent said wedges; and
said second coating thickness being greater than said first coating thickness.
10. The honeycomb body according to claim 9 , wherein said at least one metallic layer includes at least one smooth metallic nonwoven and at least one corrugated metal foil.
11. The honeycomb body according to claim 9 , wherein the honeycomb body is an open particle separator or a closed filter.
12. The honeycomb body according to claim 9 , wherein said first coating thickness and said second coating thickness abut one another.