Abstract:
A heat-shielding cover operatively adapted for being installed adjacent to an exhaust system part (C) so as to cover the same; the heat-shielding cover including a fabric ( 10 ) provided with a prescribed shape and comprising inorganic fibers, and a mixture ( 11 ) that impregnates the fabric ( 10 ), with the mixture comprising an inorganic binder, inorganic filler particles and water. The mixture is dried so as to be rigid enough to maintain the shape of the fabric ( 10 ). The heat-shielding cover covers an exhaust system part, where the heat-shielding cover has a simple structure, is less likely to be, or is not, subject to warping in the place of installation due to thermal expansion and contraction of the heat-shielding cover, and moreover is less, or is not, susceptible to galvanic corrosion, even as a result of direct installation using an installation member.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a heat-shielding cover of an exhaust system part. Heat-shielding covers are often installed on the exhaust system part, covering the same, using an installation member. Heat-shielding covers can be used to prevent thermal damage to the exhaust system part from high temperature of an internal combustion engine. The present invention also relates to a method of production thereof. 
       BACKGROUND 
       [0002]    Heat-shielding cover for an exhaust system part is already known, as is disclosed in Japanese Unexamined Patent Publication No. 2010-156372. A heat-shielding cover of an exhaust system part disclosed in Japanese Unexamined Patent Publication No. 2010-156372 includes an aluminum sheet having a comparatively large thermal expansion coefficient. Accordingly, in this sort of heat-shielding cover, a metal buffer material is interposed between the heat-shielding cover and the installation member so that warping due to thermal expansion and contraction of the heat-shielding cover does not occur in the installation member of the heat-shielding cover and impair the durability of the same; therefore, the structure surrounding the installation member becomes complex, and moreover, countermeasures for galvanic corrosion occurring due to the use of heterogeneous metals also are required surrounding the installation member. 
       SUMMARY 
       [0003]    The present invention was created, in part, in consideration of such circumstances. An object of the present invention is to provide a heat-shielding cover of an exhaust system part, that has one or any combination of the following advantages: a simple structure, is not subject to warping in the place of installation due to thermal expansion and contraction of the heat-shielding cover, and is not susceptible to galvanic corrosion, even as a result of direct installation using an installation member. Another object of the present invention is to provide a method of production thereof. 
         [0004]    A first aspect of the present invention is a heat shield or heat-shielding cover operatively adapted (i.e., dimensioned, designed, and/or configured) for being installed adjacent to an exhaust system part so as to cover the same; the heat-shielding cover including a fabric provided with a prescribed shape and comprising inorganic fibers, and a mixture that impregnates the fabric, with the mixture including an inorganic binder, inorganic filler particles and water. The mixture is dried so as to be rigid enough to maintain the shape of the fabric. It is desirable for the fabric to be a woven or knitted fabric. One example of an exhaust system part suitable for use with the present invention is a catalytic converter. 
         [0005]    A second aspect of the present invention is such that, in addition to the first aspect, the fabric is provided with at least a portion overlaid in multiple layers. 
         [0006]    A third aspect of the present invention is an exhaust system that includes an exhaust system part and a heat-shielding cover, according to the first aspect, installed adjacent to the exhaust system part so as to cover the same. 
         [0007]    A fourth aspect of the present invention is such that, during production of the heat-shielding cover according to the first aspect, the following steps are carried out: a step of molding a fabric impregnated with the mixture into the prescribed shape using at least one die, and a step of heating the die to to dry the mixture so as to be rigid enough to maintain the shape of the fabric. 
         [0008]    A fifth aspect of the present invention is such that, in addition to the fourth aspect, releasing means not easily adhered to by the mixture is interposed between each die and the impregnated fabric. 
         [0009]    According to the first aspect of the present invention, because the heat-shielding cover includes a fabric provided with a prescribed shape, and the mixture that impregnates the fabric is dried to maintain the shape of the fabric, the heat-shielding cover is excellent in heat-insulating property, and thermal damage to various kinds of devices or objects adjacent to the heat-shielding cover can be effectively prevented or at least significantly reduced. Moreover, because the heat-shielding cover has a very small thermal expansion coefficient and has a suitable degree of flexibility, the heat-shielding cover can follow thermal expansion and contraction of the exhaust system part (e.g., a catalytic converter, exhaust manifold, exhaust pipe, muffler, diesel particulate filter or trap, etc.), and there is no occurrence of thermal warping in the place of installation on the exhaust system part. Accordingly, direct installation of the heat-shielding cover using an installation member becomes possible, the installation structure can become simple, and a contribution can be made to cost reduction. Furthermore, because the heat-shielding cover can be made without metal components, the susceptibility of galvanic corrosion in the place of installation can be eliminated or at least significantly reduced. 
         [0010]    According to the second aspect of the present invention, because the fabric is provided with at least a portion overlaid in multiple layers, the heat-insulating property and/or strength of the heat-shielding cover can be increased, at least at the portion overlaid in multiple layers. 
         [0011]    According to the third aspect of the present invention, because an exhaust system is provided that includes an exhaust system part and a heat-shielding cover installed adjacent to the exhaust system part so as to cover the same, thermal damage to the exhaust system part located adjacent to the heat-shielding cover, or thermal damage to other devices or objects by heat from the exhaust system part located adjacent to the heat-shielding cover, can be effectively prevented or at least significantly reduced. 
         [0012]    According to the fourth aspect of the present invention, in production of the heat-shielding cover of the first aspect, because the method includes a step of molding a fabric impregnated with a mixture into a prescribed shape using one or more dies, and a step of heating at least one die to dry the mixture so as to be rigid enough so the fabric maintains the prescribed shape, the fabric impregnated with the mixture can be provided with a shape using the one or more dies, the clay can be dried, and the heat-shielding cover can be produced efficiently. 
         [0013]    According to the fifth aspect of the present invention, because releasing means not easily adhered to by the mixture is interposed between the dies and the impregnated fabric, the releasing means can be used to prevent the mixture from adhering to the dies. The releasing means corresponding to a releasing sheet  19 , in one embodiment of the present invention, is to be described. The releasing means may also be a coating of a suitable release material applied to the surface of the dies to be in contact with the impregnated fabric. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a side view of a catalytic converter for exhaust purification having a heat-shielding cover of the present invention installed. 
           [0015]      FIG. 2  is a perspective view of the heat-shielding cover. 
           [0016]      FIG. 3  is a cross-sectional view along line  3 - 3  in  FIG. 2 . 
           [0017]      FIG. 4  is a cross-sectional view along line  4 - 4  in  FIG. 2 . 
           [0018]      FIG. 5  is a cross-sectional view illustrating the state in which a material is set in molding dies during production of the heat-shielding cover. 
           [0019]      FIG. 6  is a cross-sectional view illustrating the state in which the material was molded into a heat shielding cover using the dies. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    An exemplary embodiment of the present invention is described below based on the attached drawings. 
         [0021]    First, in  FIG. 1 , reference numeral C indicates a catalytic converter for cleaning exhaust of an internal combustion engine of, e.g., an automobile. The catalytic converter is arranged with a length direction thereof turned vertically, between the internal combustion engine and a dashboard (not illustrated) on the body of the automobile. Respective flanges are formed on the catalytic converter, including an entrance flange  1  on an upstream upper end thereof, to which is joined a downstream end of an exhaust manifold (not illustrated) of the internal combustion engine, and an exit flange  2  on a downstream lower end thereof, to which an exhaust pipe (not illustrated) is connected. Accordingly, the catalytic converter C constitutes one part of the exhaust system of the internal combustion engine, and a heat-shielding cover  3  for covering a side surface facing a member or structure adjacent to the catalytic converter C, for example the dashboard, is installed between the entrance flange  1  and the exit flange  2  on the catalytic converter C. That is, as illustrated in  FIGS. 1 and 4 , cover stays  4  are fixed by welding or the like in a plurality of places on the outer surface of the catalytic converter C, each cover stay  4  is provided with a through-hole  5  and a welding nut  6 , a through-hole  7  matching the abovementioned through-hole  5  is provided at corresponding locations through the heat-shielding cover  3 , and a bolt  8  is fixed by screwing into and bounding tightly to the welding nut  6  through the through-holes  5  and  7 , whereby the heat-shielding cover  3  is fastened to the cover stays  4 . 
         [0022]    As illustrated in  FIGS. 2 and 3 , the heat-shielding cover  3  includes a woven fabric  10  of inorganic fibers provided with a prescribed shape so as to follow the outside surface of the catalytic converter C. A mixture  11  such as an aqueous mixture of an inorganic binder, inorganic filler particles and water impregnates the woven fabric  10  and is dried to maintain the shape of the woven fabric  10 . The woven fabric  10  can be made using glass fiber or other heat-resistant fiber. 
         [0023]    The fabric can comprise inorganic fibers (e.g., continuous glass fibers, silica fibers, basalt fibers, polycrystalline fibers, heat treated refractory ceramic fibers or any combination thereof,) suitable for being formed into a fabric such as, for example, one or any combination of woven, and/or knitted into a fabric. A fabric preferably refers to a woven fabric, knitted fabric or a combination of these types of fabric. Only fabrics with sufficient structural integrity are useful in the present invention. For example, it is desirable for a fabric according to the present invention to exhibit sufficient strength (e.g., tensile strength) to survive being impregnated with the mixture, formed, dried and used as a heat shield. A fabric according to the present invention can be made from the same or different types of fibers. As discussed herein, the fabric of the heat-shielding cover is saturated, soaked, coated, sprayed or otherwise impregnated throughout all, most or at least a substantial portion of its thickness with the aqueous mixture so as to be wet and pliable. The fabric can be impregnated with the aqueous mixture before or after being formed into the shape of the heat-shielding cover. After impregnation, the heat-shielding cover is pliable. It is dried so as to form a rigid heat-shielding cover. As used herein, the term “dried” refers to the pliable heat-shielding cover being heated to a temperature that is hot enough and for a time that is long enough to cause the pliable heat-shielding cover (i.e., the aqueous mixture) to harden and become a rigid heat-shielding cover (i.e., a rigid mixture). 
         [0024]    The aqueous mixture used to impregnate the fabric of exemplary heat-shielding cover is typically a slurry comprising water, an inorganic binder and inorganic filler particles, like that disclosed in International PCT Application Publication Number WO 2013/044012 A1, which is incorporated herein by reference in its entirety. Although the weight percent of each component within the slurry may vary, typically a given slurry comprises from about 20.0 to about 54.0 percent by weight (pbw) of water, from about 1.0 to about 36.0 pbw of one or more inorganic binders, and from about 10.0 to about 70.0 pbw of inorganic filler particles, based on a total weight of the slurry. More typically, a given slurry comprises from about 22.0 to about 45.0 pbw of water, from about 5.0 to about 30.0 pbw of one or more inorganic binders, and from about 20.0 to about 55.0 pbw of inorganic filler particles, based on a total weight of the slurry. 
         [0025]    Although the particle size of the inorganic binder material is not limited, typically, the inorganic binder comprises inorganic binder particles having a maximum particle size of about 200 nm, preferably a maximum particle size of about 100 nm. More typically, the inorganic binder comprises inorganic binder particles having a particle size ranging from about 1.0 to about 100 nm. Even more typically, the inorganic binder comprises inorganic binder particles having a particle size ranging from about 4.0 to about 60 nm. 
         [0026]    Further, although the particle size of the inorganic filler particles is not limited, typically, the inorganic filler particles have a maximum particle size of about 100 microns (μm). More typically, the inorganic filler particles have a particle size ranging from about 0.1 μm to about 100 μm. Even more typically, the inorganic filler particles have a particle size ranging from about 0.2 μm to about 50 μm. 
         [0027]    The woven fabric  10  can be overlaid in multiple layers that overlap partially or completely. In the illustrated example, two layers of the impregnated fabric  10  partially overlap. The use of such multiple layers of the fabric  10  may be particularly desirable in portions of the heat-shielding cover  3  such as, for example, a portion requiring higher heat-shielding properties (e.g., a portion of the heat shield  3  covering a center portion of the catalytic converter C that comes to a particularly high temperature). Other areas for multiple layers of the fabric  10  can include portions where additional strength and/or toughness is required such as, for example, a passive binding (e.g., see the washer shaped piece of fabric  10  shown in  FIG. 4  that partially defines the through-hole  7 ). 
         [0028]    The woven fabric  10  can be provided with a plurality of slit-shaped or round heat-discharge holes  12  as needed. Moreover, a large number of mesh holes formed by the woven fabric  10  may be left unfilled with the mixture  11  so as to remain as ventilation holes. 
         [0029]    The operation of this embodiment is next described. 
         [0030]    During operation of the internal combustion engine, the catalytic converter C of the exhaust system of the internal combustion engine cleans the exhaust gas and is brought to a high temperature from the reaction heat of the cleaning. However, because the side surface of the catalytic converter C is covered by the heat-shielding cover  3 , the heat-shielding cover  3  shields against the radiant heat of the catalytic converter C and prevents thermal damage to various kinds of devices or objects (e.g., organic matter on the ground underneath the catalytic converter C) adjacent to the catalytic converter C. 
         [0031]    The heat-shielding cover  3  is also excellent in acoustic shielding, and can effectively shield against exhaust noise generated by the catalytic converter C. 
         [0032]    The hot gas produced around the catalytic converter C is dissipated to the outside through the heat-discharge holes  12  and  12  . . . of the heat-shielding cover  3  or the large number of mesh holes of the woven fabric  10  configuring the heat-shielding cover  3 . Therefore, overheating of the catalytic converter C can be prevented. 
         [0033]    Moreover, as previously described, the heat-shielding cover  3  is configured with the woven fabric  10  containing a heat-resistant fiber  10 , and with clay  11  that is impregnated within heat-resistant fiber  10  and dried. Therefore, the heat-shielding cover is excellent in heat-insulating property, and thermal damage to various kinds of devices adjacent thereto can be effectively prevented. 
         [0034]    Because the heat-shielding cover  3  has a very small thermal expansion coefficient and has a suitable degree of flexibility, the heat-shielding cover can comply with thermal expansion and contraction of the catalytic converter C and there is no occurrence of thermal warping in the part fastened using the bolt  8 . Accordingly, direct binding of the heat-shielding cover  3  using the bolt  8  becomes possible and a contribution is made to cost reduction. 
         [0035]    Moreover, because the heat-shielding cover  3  has an insulating property, there is also no susceptibility to the occurrence of galvanic corrosion in the part bound using the bolt  8 . 
         [0036]    The following Examples of material combinations have been selected merely to further illustrate potential features, advantages, and other details of the invention. It is to be expressly understood, however, that while the Examples serve this purpose, the particular ingredients and amounts used as well as other conditions and details are not to be construed in a manner that would unduly limit the scope of this invention. 
       EXAMPLES 
       [0037]    The following materials as shown in Table 1 can be used in accordance with the present invention: 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Materials 
               
             
          
           
               
                   
                 Description 
                 Source 
               
               
                   
                   
               
             
          
           
               
                 Fabrics 
                   
                   
               
               
                 ECG heat set knit 
                 2″ 3″ or 4″ wide 
                 3M, St. Paul MN 
               
               
                   
                 SCOTCHCAST ™ knit heat 
               
               
                   
                 treated G yarn 
               
               
                 ECG non-heat set knit 
                 3″ wide SCOTCHCAST ™ knit 
                 3M, St. Paul MN 
               
               
                   
                 not heat treated G yarn 
               
               
                 ECDE heat set knit 
                 4″ wide SCOTCHCAST ™ knit 
                 3M, St. Paul MN 
               
               
                   
                 heat treated DE yarn 
               
               
                 silica weave 
                 TECSIL ® 3″ 13-621 
                 Intec, Anaheim CA 
               
               
                 e-glass weave 
                 #8817K68 
                 McMaster-Carr, Chicago IL 
               
               
                 Inorganic Binder 
               
               
                 colloidal silica 4 nm 
                 NALCO ™ 1115 
                 Nalco, Chicago IL 
               
               
                 colloidal silica 15 nm 
                 NALCO ™ 1144 
                 Nalco, Chicago IL 
               
               
                 colloidal silica 20 nm 
                 NALCO ™ 2327 
                 Nalco, Chicago IL 
               
               
                 colloidal silica 60 nm 
                 NALCO ™ 1060 
                 Nalco, Chicago IL 
               
               
                 colloidal alumina 50 nm 
                 NYACOL ® AL20 
                 Nyacol, Ashland MA 
               
               
                 colloidal silica 8 nm 
                 LUDOX ® SM 
                 Grace Davidson Columbia MD 
               
               
                 Colloidal silica positively 
                 Ludox CL-P 
                 Grace Davidson Columbia MD 
               
               
                 charged 
               
               
                 Colloidal silica deionized 
                 Ludox TMA 
                 Grace Davidson Columbia MD 
               
               
                 Colloidal silica 20 nm positive 
                 NALCO 1056 
                 Nalco, Chicago, IL 
               
               
                 charge 
               
               
                 Colloidal silica sterically 
                 Bindzil cc401 
                 AkzoNobel, Marietta, GA 
               
               
                 stabilized 
               
               
                 Colloidal silica positive charge 
                 Bindzil CAT80 
                 AkzoNobel, Marietta, GA 
               
               
                 wide particle size range 
               
               
                 Colloidal silica neutral pH 
                 Bindzil DP5100 
                 AkzoNobel, Marietta, GA 
               
               
                 sodium silicate 
                 STIXO ™ NN 
                 PQ Corporation, Valley Forge PA 
               
               
                 Inorganic Fillers and 
               
               
                 Additives 
               
               
                 kaolin clay 
                 POLYPLATE ™ P 
                 KaMin, Macon GA 
               
               
                 calcined kaolin 
                 2000C 
                 KaMin, Macon GA 
               
               
                 bentonite clay 
                 BENTOLITE ® 
                 Southern Clay Gonzales TX 
               
               
                 aluminum hydroxide 1 
                 Huber ONYX ELITE ® 
                 Huber, Norcross GA 
               
               
                 aluminum hydroxide 2 
                 MARTINAL ® OL-104 LE 
                 Albemarle, Baton Rouge LA 
               
               
                 fumed silica 
                 CAB-O-SIL ® M-5 
                 Cabot, Boston MA 
               
               
                 fumed alumina 
                 SpectrAl ® grade 51 
                 Cabot, Boston MA 
               
               
                 alumina powder 
                 Type A 
                 Fisher Scientific, Fairlawn NJ 
               
               
                 precipitated silica 
                 ZEOTHIX ® 265 
                 Huber, Norcross, GA 
               
               
                 ground silica 1 
                 MIN-U-SIL ™ 10 
                 U.S. Silica, Frederick MD 
               
               
                 ground silica 2 
                 MIN-U-SIL ™ 30 
                 U.S. Silica, Frederick MD 
               
               
                 aluminum powder 
                 325 mesh #11067 
                 Alfa/Aesar, Ward Hill MA 
               
               
                 Talc 
                 talc powder 
                 J. T. Baker, Phillipsburg NJ 
               
               
                 aluminum silicate 
                 #14231 
                 Alfa/Aesar, Ward Hill MA 
               
               
                 calcium silicate 
                 MICRO-CEL ® 
                 Celiter Corp., Lompoc CA 
               
               
                 calcium carbonate 
                   
                 Sigma Aldrich, St. Louis MO 
               
               
                 silicon carbide 
                 800W 
                 Electro Abrasives, Buffalo NY 
               
               
                 glass bubbles 
                 SCOTCHLITE ™ K37 
                 3M, St. Paul MN 
               
               
                 glass frit 
                 EG02934VEG 
                 Ferro, Cleveland OH 
               
               
                 titanium dioxide 
                 R900 
                 Dupont, Wilmington DE 
               
               
                 sodium hydroxide 
                 Pellets 
                 EMD, Germany 
               
               
                 nitric acid 
                 69% Nitric acid 
                 J. T. Baker, Phillipsburg NJ 
               
               
                 Kaolin clay 
                 Dixie clay 
                 R. T. Vanderbuilt, Norwalk, CT 
               
               
                 Wollastonite 
                 Vansil 50 
                 R. T. Vanderbuilt, Norwalk, CT 
               
               
                 Manganese Ferrite 
                 FM-2400 
                 Rockwood, Beltsville, MD 
               
               
                 Silane 
                 Z-6040 
                 Dow-Corning, Midland MI 
               
               
                   
               
             
          
         
       
     
         [0038]    Slurries can be prepared using ingredients shown above. In each slurry, inorganic materials can be added to liquid component(s) using a high shear mixer and blended until smooth to form a given slurry as shown in Table 2 below. 
         [0000]    
       
         
               
             
               
               
             
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Slurries 
               
             
          
           
               
                 Slurry 
                 Composition 
               
               
                   
               
             
          
           
               
                 1 
                 50 wt % 2327 colloidal silica, 50 wt % POLYPLATE ™ P 
               
               
                 2 
                 67 wt % 2327 colloidal silica, 33 wt % calcium carbonate 
               
               
                 3 
                 57.1 wt % 1144 colloidal silica, 42.9 wt % calcium carbonate 
               
               
                 4 
                 94.4 wt % 2327 colloidal silica, 5.6 wt % M-5 fumed silica 
               
               
                 5 
                 87.8 wt % 1144 colloidal silica, 12.2 wt % M-5 fumed silica 
               
               
                 6 
                 60 wt % 2327 colloidal silica, 40 wt % talc 
               
               
                 7 
                 52.9 wt % 1144 colloidal silica, 47.1 wt % talc 
               
               
                 8 
                 60 wt % 2327 colloidal silica, 40 wt % silicon carbide 
               
               
                 9 
                 50 wt % 2327 colloidal silica, 40 wt % aluminum powder, 
               
               
                   
                 10 wt % POLYPLATE ™ P 
               
               
                 10 
                 82.3 wt % 2327 colloidal silica, 17.7 wt % bentonite clay 
               
               
                 11 
                 84 wt % 2327 colloidal silica, 16 wt % fumed alumina 
               
               
                 12 
                 84.4 wt % 2327 colloidal silica, 15.6 wt % glass bubbles 
               
               
                 13 
                 50 wt % 2327 colloidal silica, 50 wt % titanium dioxide 
               
               
                 14 
                 66.7 wt % 2327 colloidal silica, 33.3 wt % alumina powder 
               
               
                 15 
                 84.2 wt % 2327 colloidal silica, 15.8 wt % precipitated silica 
               
               
                 16 
                 50 wt % 2327 colloidal silica, 50 wt % aluminum silicate 
               
               
                 17 
                 42.1 wt % 2327 colloidal silica, 57.9 wt % aluminum hydroxide-1 
               
               
                 18 
                 42.1 wt % 2326 colloidal silica, 57.9 wt % ground silica 1 
               
               
                 19 
                 42.1 wt % 2327 colloidal silica, 57.9 wt % ground silica 2 
               
               
                 20 
                 45.3 wt % 2327 colloidal silica, 50.0 wt % silica 1, 2.8 wt % silicon carbide, 
               
               
                   
                 1.8 wt % bentonite clay 
               
               
                 21 
                 60 wt % 2327 colloidal silica, 40 wt % POLYPLATE ™ P 
               
               
                 22 
                 60 wt % 2327 colloidal silica, 40 wt % 2000C calcined clay 
               
               
                 23 
                 44.5 wt % colloidal silica 1144, 33.3 wt % glass frit, 22.2 wt % 2000C 
               
               
                 24 
                 60 wt % SM colloidal silica, 40 wt % POLYPLATE ™ P 
               
               
                 25 
                 50 wt % 2327 colloidal silica, 50 wt % POLYPLATE ™ P 
               
               
                 26 
                 50 wt % 4 nm colloidal silica, 50 wt % POLYPLATE ™ P 
               
               
                 27 
                 50 wt % 60 nm colloidal silica, 50 wt % POLYPLATE ™ P 
               
               
                 28 
                 50 wt % 1144 colloidal silica, 50 wt % POLYPLATE ™ P 
               
               
                 29 
                 60 wt % colloidal alumina, 40 wt % POLYPLATE ™ P 
               
               
                 30 
                 100 wt % 2327 colloidal silica 
               
               
                 31 
                 100 wt % 4 nm colloidal silica 
               
               
                 32 
                 90 wt % 2327 colloidal silica, 10 wt % POLYPLATE ™ P 
               
               
                 33 
                 80 wt % 2327 colloidal silica, 20 wt % POLYPLATE ™ P 
               
               
                 34 
                 70 wt % 2327 colloidal silica, 30 wt % POLYPLATE ™ P 
               
               
                 35 
                 60 wt % 2327 colloidal silica 40 wt % POLYPLATE ™ P 
               
               
                 36 
                 100 wt % sodium silicate solution 
               
               
                 37 
                 80 wt % 2327 colloidal silica, 20 wt % 2000C 
               
               
                 38 
                 70 wt % 2327 colloidal silica, 30 wt % 2000C 
               
               
                 39 
                 60 wt % 2327 colloidal silica, 40 wt % 2000C 
               
               
                 40 
                 74.4 wt % sodium silicate, 18.6 wt % POLYPLATE ™ P, 7 wt % water 
               
               
                 41 
                 12.5 wt % sodium silicate, 50 wt % POLYPLATE ™ P, 37.5 wt % water 
               
               
                 42 
                 28.6 wt % sodium silicate, 42.8 wt % POLYPLATE ™ P, 28.6 wt % water 
               
               
                 43 
                 45 wt % 2327 colloidal silica, 50 wt % POLYPLATE ™ P, 5 wt % titanium dioxide 
               
               
                 44 
                 40 wt % sodium silicate, 30 wt % POLYPLATE ™ P, 30 wt % water 
               
               
                 45 
                 29.4 wt % sodium silicate, 35.3 wt % POLYPLATE ™ P, 35.3 wt % water 
               
               
                 46 
                 14.3 wt % sodium silicate, 42.8 wt % POLYPLATE ™ P, 42.8 wt % water 
               
               
                 47 
                 60 wt % POLYPLATE ™ P, 40 wt % water 
               
               
                 48 
                 69.5 wt % POLYPLATE ™ P, 30.5 wt % water 
               
               
                 49 
                 15 wt % 2327 colloidal silica, 55 wt % POLYPLATE ™ P, 30 wt % water 
               
               
                 50 
                 31 wt % 2327 colloidal silica, 49 wt % POLYPLATE ™ P, 20 wt % water 
               
               
                 51 
                 7.7 wt % sodium silicate, 46.2 wt % POLYPLATE ™ P, 46.2 wt % water 
               
               
                 52 
                 10 wt % sodium silicate, 90 wt % water 
               
               
                 53 
                 25 wt % sodium silicate, 75 wt % water 
               
               
                 54 
                 50 wt % sodium silicate, 50 wt % water 
               
               
                 55 
                 90.2 wt % 1144 colloidal silica, 9.8 wt % POLYPLATE ™ P 
               
               
                 56 
                 50 wt % 2327 colloidal silica, 33 wt % POLYPLATE ™ P, 17 wt % 2000C 
               
               
                 57 
                 55 wt % 2327 colloidal silica, 30 wt % POLYPLATE ™ P, 15 wt % 2000C 
               
               
                 58 
                 52.4 wt % 2327 colloidal silica, 31.7 wt % POLYPLATE ™ P, 15.8 wt % 2000C 
               
               
                 59 
                 7.9 wt % 4 nm colloidal silica, 68.3 wt % POLYPLATE ™ P, 23.7 wt % water 
               
               
                 60 
                 50 wt % 2327, 50 wt % aluminum hydroxide -2 
               
               
                 61 
                 44.5 wt % 1144 colloidal silica, 33.3 wt % glass frit, 22.2 wt % 2000C clay 
               
               
                 62 
                 53.3 wt % nitric acid treated 1144 colloidal silica*, 46.7 wt % POLYPLATE ™ P 
               
               
                   
                 *Nitric acid added with stirring to 1144 colloidal silica until pH 2.3 is achieved. 
               
               
                 63 
                 83.7 wt % 1144 colloidal silica, 16.3 wt % calcium silicate 
               
               
                 64 
                 50% 1056 colloidal silica, 18% 2000C clay, 32% POLYPLATE ™ P 
               
               
                 65 
                 50% 1056 colloidal silica, 50% Dixie clay 
               
               
                 66 
                 50% 1144 colloidal silica, 50% Vansil 50 
               
               
                 67 
                 53% Cat 80 colloidal silica, 47% POLYPLATE P 
               
               
                 68 
                 50% cc401 colloidal silica, 45% POLYPLATE P, 5% FM2400 
               
               
                 69 
                 50% DP5110 colloidal silica, 45% POLYPLATE P, 5% FM2400 
               
               
                 70 
                 50% 1056 colloidal silica, 45% POLYPLATE P, 5% FM2400 
               
               
                 71 
                 53% cat 80 colloidal silica 42% Dixie clay, 5% FM2400 
               
               
                 72 
                 54% Ludox CL-P colloidal silica, 46% POLYPLATE P 
               
               
                 73 
                 50% Ludox TMA colloidal silica, 50% POLYPLATE P 
               
               
                 74 
                 25% 1056 colloidal silica, 25% Cat 80 colloidal silica, 25% Polyplate P, 25% Dixie clay 
               
               
                 75 
                 25% 1056 colloidal silica, 25% Cat 80 colloidal silica, 25% POLYPLATE P, 25% Dixie 
               
               
                   
                 clay + 0.33% Z-6040 silane 
               
               
                   
               
             
          
         
       
     
         [0039]    Each exemplary fabric can be impregnated with a given slurry to produce a given pliable heat-shielding cover, and subsequently formed and dried into a rigid heat-shielding cover via a drying/heat treatment molding procedure like that described below. 
         [0040]    An exemplary method of production of the heat-shielding cover  3  is next described while referring to  FIG. 5 . 
         [0041]    A pair of upper and lower dies  15  and  16  for press-molding the heat-shielding cover  3  is prepared. Heaters  17  and  17  are embedded in the dies  15  and  16 , and a plurality of steam escape slots  18  and  18  . . . is provided on facing surfaces of the dies  15  and  16 . 
         [0042]    When molding the heat-shielding cover  3 , first, a releasing sheet  19  (e.g., made using aluminum foil) is laid on the lower die  16 . A plurality of steam escape holes is provided in the releasing sheet  19  for the water in the mixture  11  to escape through when heated. A woven fabric  10  impregnated with aqueous mixture  11  is set on the releasing sheet  19 . Then, as previously described, woven fabric  10  impregnated with mixture  11  is placed in multiple layers in places requiring high heat-shielding property or places requiring strength on the heat-shielding cover  3 . 
         [0043]    Moreover, a releasing sheet  19  of the same kind as mentioned above is laid on the woven fabric  10 , and then, as illustrated in  FIG. 6 , the upper die  15  is lowered, sandwiching the impregnated woven fabric  10  against the lower die  16 , the woven fabric  10  is provided with a prescribed shape as a heat-shielding cover  3 . In this manner, the heat-discharging slits  12  and  12  . . . are punched into the woven fabric  10  by joint operation of the two dies  15  and  16 . Next, the heaters  17  and  17  are started, and the mixture  11  impregnating the woven fabric  10  is dried. The steam produced at that time is discharged through the steam escape holes of the releasing sheet  19  or the steam escape slots  18  and  18  . . . of the dies  15  and  16 . Thus, the dried and hardened mixture  11  maintains the shape of the woven fabric  10  provided by the dies  15  and  16 , and the heat-shielding cover  3  is configured together with the woven fabric  10 . After that, the upper die  15  is raised, and the heat-shielding cover  3  can be removed from between the two dies  15  and  16  together with the upper and lower releasing sheets  19  and  19 . Thus, because the releasing sheets  19  and  19  prevent the mixture  11  from adhering to the dies  15  and  16  and also prevent the mixture  11  from adhering to the releasing sheets  19  and  19  themselves, the releasing sheets can be easily removed from the heat-shielding cover  3 . 
         [0044]    According to such production method, a shape can be provided to a woven fabric  10  impregnated with mixture  10 , and a heat-shielding cover  3  can be produced efficiently, using a pair of upper and lower dies  15  and  16 . 
         [0045]    The present invention is not limited to the abovementioned embodiment, and all kinds of design modifications are possible within a scope that does not deviate from the main point thereof. For example, a metal mesh, porous steel sheet, or other reinforcing material may be sandwiched between woven fabrics  10  overlaid in a plurality of sheets, or the reinforcing material may be provided on the top surface. Additionally, the material of the reinforcing material is not limited to metal, and may also be a heat-resistant resin or ceramic. Moreover, the heat-shielding cover  3  can be installed on the catalytic converter C using a band, or the like, instead of one or more bolts  8 . Additionally, a releasing powder can be used on the dies  15  and  16  instead of the releasing sheet  19 . The releasing sheets  19  and  19  may also be replaced with a coating of conventional release material that adheres to the dies  15  and  16  but not the heat-shielding cover  3 . Moreover, the shape of the heat-shielding cover can be freely selected in accordance with the type or arrangement of the exhaust system part or with the arrangement of adjacent members. Furthermore, the present invention may be useful as a heat shield for applications other than for an exhaust system part. On such other application may be, for example, as a heat shield for other heat generating structures or for protecting heat sensitive areas of a structure.