Exhaust device having a heat-insulating layer comprising inorganic microballoons and a refractory layer and method of manufacturing same

Claim 1

An exhaust device comprising: a metal portion for passing high temperature exhaust gases therethrough, said metal portion having interior surfaces; a heat-insulating layer adhered directly to said interior surfaces, said heat-insulating layer consisting of heat-resistant microballoons having a particle size in the range of from about 10 to 500 μm and an inorganic binder, said heat-insulating layer having a thickness of greater than about 1.5 mm; and a refractory layer consisting essentially of a refractory material having a particle size of about 10 to 500 μm and an inorganic binder, said refractory layer overlaying said heat insulating layer and having a thickness greater than about 0.5 mm.

Claim 3

A method of manufacturing an exhaust device having on its inner surface a heat-insulating layer and a refractory layer, comprising: a first step of forming said heat-insulating layer by conducting at least one cycle of the following steps: (a) coating said inner surface with an inorganic binder solution; (b) immediately adhering heat-insulating microballoons to the inorganic binder solution layer, said microballoons being fully and uniformly impregnated with said inorganic binder solution; and (c) drying and solidifying the resulting heat-insulating microballoon layer by heat treatment; and a second step of forming a refractory layer by conducting at least one cycle of the following steps: (d) coating the surface of said heat-insulating layer with an inorganic binder solution, (e) immediately adhering a refractory material to the inorganic binder solution layer, said refractory material being fully and uniformly impregnated with said inorganic binder solution; and (f) drying and solidifying the resulting refractory material layer by heat treatment.

Claim 4

A method of manufacturing an exhaust device having on its inner surface a heat-insulating layer and a refractory layer, comprising: a first step of forming said heat-insulating layer by conducting at least one cycle of the following steps: (a) coating said inner surface with an inorganic binder solution; (b) immediately adhering heat-insulating microballoons to the inorganic binder solution layer, said microballoons being fully and uniformly impregnated with said inorganic binder solution; and (c) drying and solidifying the resulting heat-insulating microballoon layer by heat treatment; and a second step of forming a refractory layer by conducting at least one cycle of the following steps: (d) coating the surface of said heat-insulating layer with an inorganic binder solution, (e) immediately adhering a refractory material to the inorganic binder solution layer, said refractory material being fully and uniformly impregnated with said inorganic binder solution; and (f) drying and solidifying the resulting refractory material layer by heat treatment.

Claim 6

A method of manufacturing an exhaust device comprising the steps of: providing a metal member disposed to conduct high temperature exhaust gases therethrough, said metal member having interior surfaces; forming a heat-insulating layer on said interior surface, said heat-insulating layer being comprised of a layer of heat-resistant microballoons of from 10 to 500 μm in diameter, said layer having a thickness of at least about 1.5 mm, said heat-insulating layer being formed by conducting at least one cycle of the following steps: (a) coating said interior surfaces with an inorganic binder solution; (b) adhering heat-resistant microballoons to the inorganic binder on said surfaces, said microballoons being fully and uniformly impregnated with said inorganic binder solution; (c) drying and solidifying said heat-insulating layer; and forming a refractory layer from powdered heat resistant refractory material having a particle size in the range of from 10 to 500 μm wherein said refractory layer has a thickness of at least about 0.5 mm, said refractory layer being formed by conducting at least one cycle of the following steps: (d) coating the surface of said heat-insulating layer with an organic binder solution; (e) adhering said powdered refractory material to said inorganic binder solution on said heat-insulating layer, said powdered refractory material being fully and uniformly impregnated with said inorganic binder solution; and (f) drying and solidifying said refractory layer.

Claim 7

A method of manufacturing an exhaust device comprising the steps of: providing a metal member disposed to conduct high temperature exhaust gases therethrough, said metal member having interior surfaces; forming a heat-insulating layer on said interior surface, said heat-insulating layer being comprised of a layer of heat-resistant microballoons of from 10 to 500 μm in diameter, said layer having a thickness of at least about 1.5 mm, said heat-insulating layer being formed by conducting at least one cycle of the following steps: (a) coating said interior surfaces with an inorganic binder solution; (b) adhering heat-resistant microballoons to the inorganic binder on said surfaces, said microballoons being fully and uniformly impregnated with said inorganic binder solution; (c) drying and solidifying said heat-insulating layer; and forming a refractory layer from powdered heat resistant refractory material having a particle size in the range of from 10 to 500 μm wherein said refractory layer has a thickness of at least about 0.5 mm, said refractory layer being formed by conducting at least one cycle of the following steps: (d) coating the surface of said heat-insulating layer with an organic binder solution; (e) adhering said powdered refractory material to said inorganic binder solution on said heat-insulating layer, said powdered refractory material being fully and uniformly impregnated with said inorganic binder solution; and (f) drying and solidifying said refractory layer.