Exhaust gas treatment device
View Patent ↗A device for treatment of exhaust gases includes a housing, a fragile structure resiliently mounted within the housing, and a non-intumescent mounting mat disposed in a gap between the housing and the fragile structure. The mounting mat includes a plurality of inorganic fibers that have undergone a surface treatment to increase the holding force performance of the mounting mat. Also disclosed are methods of making a mounting mat for an exhaust gas treatment device and for making an exhaust gas treatment device incorporating the mounting mat.
1. A device for treatment of exhaust gases comprising:
a housing;
a fragile structure resiliently mounted within said housing; and
a substantially non-expanding flexible mounting mat disposed in a gap between said housing and said fragile structure, wherein said mounting mat includes heat treated inorganic fibers having a holding pressure performance-increasing surface treatment thereon comprising an inorganic particulate material on at least a portion of the exterior surfaces of at least a portion of the inorganic fibers; and wherein the mounting mat has a minimum holding pressure for holding the fragile structure within the housing of one of (i) at least 50 kPa after 1000 cycles of testing at a hot face temperature of 300° C., a gap bulk density of between 0.3 and 0.5 g/cm 3 , and a percent gap expansion of 2 percent, and (ii) at least 10 kPa after 1000 cycles of testing at a hot face temperature of 900° C., a gap bulk density of between 0.3 and 0.5 g/cm 3 , and a percent gap expansion of 5 percent.
2. The device of claim 1 , wherein said fibers are selected from alumina, alumino-silicate fibers, alumina/magnesia/silica fibers, calcia/magnesia/silica fibers, magnesia/silica fibers, S-glass fibers, E-glass fibers, quartz fibers, and silica fibers.
3. The device of claim 2 , wherein said mounting mat comprises at least one integral, substantially non-expanding layer of melt-formed, leached glass fibers containing at least 67 percent by weight silica.
4. The device of claim 3 , wherein said leached glass fibers contain at least about 90 percent by weight silica.
5. The device of claim 4 , wherein said leached glass fibers contain from about 90 to about 99 percent by weight silica.
6. The device of claim 5 , wherein said leached glass fibers contain from about 93 to about 95 percent by weight silica and from about 4 to about 6 percent by weight alumina.
7. The device of claim 3 , wherein said leached glass fibers contain less than about 1 percent by weight alkali metal or alkaline earth metal.
8. The device of claim 3 , wherein said mounting mat comprises from about 50 to 100 percent by weight of said leached glass fibers.
9. The device of claim 8 , wherein said mounting mat comprises at least about 80 percent by weight of said leached glass fibers.
10. The device of claim 3 , wherein the mounting mat is substantially free of binder.
11. The device of claim 3 , wherein the leached glass fibers have a diameter greater than about 3.5 microns.
12. The device of claim 3 , wherein the leached glass fibers are substantially shot free.
13. The device of claim 3 , wherein the mounting mat contains greater than 0 to about 50 weight percent, based upon 100 percent by weight of the total mat, of S2-glass fibers or refractory ceramic fibers.
14. The device of claim 1 , wherein said holding pressure performance-increasing surface treatment comprises a coating.
15. The device of claim 14 , wherein said coating is one of a continuous or discontinuous coating.
16. The device of claim 1 , wherein said inorganic particulate material is selected from the group consisting of dispersions of colloidal alumina, colloidal silica, colloidal zirconia, or mixtures thereof.
17. The device of claim 16 , wherein said inorganic particulate comprises a friction increasing agent.
18. The device of claim 1 , wherein the mounting mat is heat treated at a temperature of at least about 900° C.
19. The device of claim 1 , wherein the device is a catalytic converter or diesel particulate trap.
20. A flexible mounting mat comprising:
heat treated inorganic fibers; and
a holding pressure performance increasing surface treatment comprising an inorganic particulate on at least a portion of the exterior surfaces of at least a portion of the inorganic fibers;
wherein said flexible mounting mat has a minimum holding pressure for holding the fragile structure within the housing of one of (i) at least 50 kPa after 1000 cycles of testing at a hot face temperature of 300° C., a gap bulk density of between 0.3 and 0.5 g/cm 3 , and a percent gap expansion of 2 percent, and (ii) at least 10 kPa after 1000 cycles of testing at a hot face temperature of 900° C., a gap bulk density of between 0.3 and 0.5 g/cm 3 , and a percent gap expansion of 5 percent.
21. The mounting mat of claim 20 , wherein said fibers are selected from alumina, alumino-silicate fibers, alumina/magnesia/silica fibers, calcia/magnesia/silica fibers, magnesia/silica fibers, S-glass fibers, E-glass fibers, quartz fibers, and silica fibers.
22. The mounting mat of claim 21 , wherein said mounting mat comprises at least one integral, substantially non-expanding layer of melt-formed, leached glass fibers containing at least 67 percent by weight silica.
23. The mounting mat of claim 22 , wherein said mounting mat comprises from about 50 to 100 percent by weight of said leached glass fibers.
24. The mounting mat of claim 23 , wherein said mounting mat comprises at least about 80 percent by weight of said leached glass fibers.
25. The mounting mat of claim 22 , wherein the mounting mat is substantially free of binder.
26. The mounting mat of claim 22 , wherein the leached glass fibers have a diameter greater than about 3.5 microns.
27. The mounting mat of claim 22 , wherein said holding pressure performance-increasing surface treatment comprises a coating.
28. The mounting mat of claim 20 , wherein said inorganic particulate is selected from the group consisting of dispersions of colloidal alumina, colloidal silica, colloidal zirconia, or mixtures thereof.
29. The mounting mat of claim 28 , wherein said inorganic particulate comprises a friction increasing agent.