JPS63225790A - Heat-insulating structure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thick three-dimensional heat insulating structure made of heat-resistant fibers.

[Prior Art] Asbestos plates and ceramic II felt are known as heat insulating materials for boilers and the like.

[Problems solved by the invention] One asbestos board each! There are problems such as the fibers peeling off from the surface due to the weak binding force between the sheets, and the insulation effect is insufficient because it is not possible to have a large gap between the sheets. Furthermore, ceramic fiber felt also has weak bonding between fibers and low mechanical strength.

An object of the present invention is to provide a novel heat insulating structure that does not have the above-mentioned problems.

[Means for Solving the Problems] The heat insulating structure of the present invention is made of a woven fabric having a heat resistance of 111ffl and having a wall thickness of at least 0.2 mm.

The heat-resistant fibers constituting the heat-insulating structure of the present invention are fibers that have heat resistance that can withstand the environment in which they are used, and include ceramics such as silica fibers, alumina fibers, zirconia fibers, silicon carbide fibers, carbon fibers, boron fibers, and glass fibers. Heat-resistant polymer fibers such as fibers and polyimide fibers can be used. Moreover, these can also be used in combination as necessary.

For the purpose of improving oxidation resistance, preventing reactions, etc., it is also useful to coat the fiber surface or knitted or woven body, or to add carbon to silicon carbide by treating it in the presence of silicon.

The knitted or woven article of the present invention has a three-dimensional structure by three-dimensionally knitting or weaving heat-resistant fiber threads or rovings in three directions (X, Y, and Z).

Woven fabrics can be classified as follows depending on the number of fiber arrangement methods. - A three-dimensional structure made by knitting together a large number of yarns arranged in the axial direction - A three-dimensional woven fabric (corresponding to the conventional 4-string fabric), consisting of a two-component system of warp and weft, with the warp being the Three-dimensional biaxial fabric made by diagonally knitting many layers of weft threads (
These include multi-structured fabrics used for belts, hoses, etc., and three-dimensional triaxial fabrics in which warp, weft, and vertical threads are organized three-dimensionally. Furthermore, it can be classified not only by the construction style, but also by the weaving method. For example, Fig. 1 shows an example of a three-dimensional triaxial fabric, and there is an orthogonal weave in which the warp, weft, and perpendicular threads intersect perpendicularly at the intersection points without meandering, and as shown in Fig. 2, the warp, weft, and perpendicular threads It is a plain weave structure that is dislocated and intersected with respect to the perpendicular system of the structure. The three-dimensional knitted fabric of the present invention may be selected from among these various three-dimensional fabric weaving methods as necessary, and is not limited to a fabric with a specific structure. It is also possible to incorporate a heat insulating material such as felt or woven fabric into the fabric.

The thickness of the knitted fabric is preferably at least 0.2 mm, more preferably 1 mm or more.

The m-vertebral volume ratio (the volume occupied by the m-vertebral bodies, and the rest is the volume occupied by the spaces) in the knitted or woven body can be in the range of several percent to about 70%. A woven fabric with uniform density may be used, but in order to prevent high-temperature gases such as exhaust gas from flowing into the woven fabric from the surface, it is preferable to use a multilayer structure in which the surface is dense, the middle part is normal, and the other side is rough. It is preferable to do so. In order to obtain such a multilayered structure, operations such as increasing the number of 41 miscellaneous weaves on the inner wall side or weaving them densely may be performed.

The knitted or woven body may be a molded body having a predetermined shape.

Specific shapes of the molded body include a tubular shape such as an exhaust pipe, a thick sheet shape, and the like. Note that a thick mtIa body may be cut into a predetermined shape and sewn together with heat-resistant fibers to obtain the desired shape.

The woven fabric of the present invention can be used by lining the inner surface of an exhaust vibe, or can be used by placing a cast metal on one side of the woven fabric.

[Operations and Effects] The knitted fabric of the present invention has threads intertwined three-dimensionally, and has higher strength than conventional two-dimensional insulation materials (improved shape retention after fiber deterioration at high temperatures). The spalling resistance, which is a problem with bricks, etc., is much better because it has a woven or knitted structural structure.In general, the lower the bulk density of the insulation material, the more pores it has) Heat conduction decreases, but if the density becomes too low, conduction by convection or radiation increases, and heat conduction throughout the insulation material increases rapidly. This effect is especially noticeable at high temperatures. In the three-dimensional FIA woven body of the present invention, the surface layer can be made to have a certain degree of bulk density to prevent gas inflow, and the other parts can be made to have a low density, and the thermal conductivity can be easily controlled. Further, since the surface of the knitted fabric of the present invention is rich in irregularities, it is easy to adhesively fix it to a wall surface that requires heat insulation.

Even when molten metal is injected into one side of the knitted fabric and the metal is cast, the surface portion of the knitted fabric becomes encapsulated in the metal, and its adhesion is greatly improved.

[Example 1] An alumina thread with a diameter of about 0.6 mm made by twisting about 1000 alumina fibers with a diameter of about 20 microns was used, and the thread structure shown in Figure 2 was 200 mm thick, both vertically and horizontally. A knitted fabric of the first example of the present invention was made with a length of 50 cm and a fiber volume percentage of about 18%.

[Example 2] Alumina thread with a diameter of about 0.6 mm made by twisting about 1000 alumina fibers with a diameter of about 20 microns was used, the first layer was 10 mm thick and the fiber volume percentage was 48%, and the second layer was A knitted fabric according to the second embodiment of the present invention was prepared, having a thickness of 190 mm, a fiber volume fraction of about 10%, a coarse and dense two-layer yarn structure, a thickness of 200 mm, and a length and width of 50 cm.

[Example 3] Using glass threads with a diameter of about 3.3 mm, which were made by twisting about 1000 glass fibers with a diameter of about 10 microns,
The third example of the present invention has the same coarse and fine two-layer yarn structure as the knitted fabric of Example 3, has a thickness of 200 mm, and has 5 layers in both length and width! I made a woven body.

[Test Example 1] Three types of knitted and woven structures of the above-mentioned first, second, and third examples, a firebrick with a thickness of 3QQmm as comparative example 1, and a felt-like alumina fiber as comparative example 2 Ceramic felt with an IIM volume fraction of 1% and a thickness of 200 mm was used, and the temperature of the outer surface of each heat insulating body was measured to examine the heat insulation properties of each heat insulator attached to the furnace wall where the temperature inside the furnace was approximately 900°C. The temperature of the outer surface of each IIA fabric in Examples 1 to 3 was 80°C, 72°C, and 70°C, respectively. On the other hand, the outer surface temperatures of the heat insulating materials of Comparative Examples 1 and 2 were 82°C and 76°C. The heat insulating properties of each knitted fabric of this example were almost the same as those of conventional heat insulating materials. However, the refractory brick of Comparative Example 1 required cement to be attached to the furnace wall, and it was necessary to close gaps. Furthermore, the felt of Comparative Example 2 had a problem in that the fibers fell off from the surface because the bond between the fibers was weak. On the other hand, fl! of each example! The adult plant had sufficient mechanical strength and was easy to attach.

[Example 4] A knitted and woven body of Example 4 having the same material, fiber volume ratio, and structure as the knitted and woven body of Example 1 and having a thickness of 5 mm was produced.

This knitted body is used as an exhaust pipe of a heat engine (outer diameter 45+++n).

It was attached to the surface of the mold to be cast with a wall thickness of 5+u, and molten aluminum was poured into it at approximately 700℃. In this case, no defects were observed during casting. Due to the heat insulating effect of this knitted fabric, the exhaust temperature of this exhaust pipe rose by about 60°C.

Furthermore, no damage was observed on the adult mama or the exhaust pipe body even after 1000 hours of operation.

[Example 5] Alumina yarn with a diameter of about Q and 2 mm made by twisting about 500 alumina fibers with a diameter of about 10 microns was used, and the first layer had a thickness of iQmm, a fiber volume percentage of about 48%, and a fiber volume ratio of about 48%. 2
Layers are 50mm thick, fiber volume percentage is approx. 18%, and has a two-layer yarn structure with an outer diameter of 180mm, an inner diameter of 120mm, and a thickness of 60mm.
A tubular knitted fabric body according to the fifth example of the present invention was made.

This knitted fabric was wound around the outer circumferential surface of a hot air tube having an outer diameter of 120 mm. In addition, conventionally, alumina castable was used as a heat insulating material by coating G. By using the knitted fabric of this example, construction was facilitated and the heat insulation efficiency was improved by about 25%.

[Brief explanation of the drawing]

FIG. 1 is a partial perspective view showing the yarn structure of the knitted fabric of the present invention;
FIG. 2 is another partial perspective view showing the thread structure of the knitted fabric of the present invention.

Claims (3)

[Claims] (1) Made of heat-resistant fibers with a thickness of at least 0.2 mm
A heat insulating structure made of a knitted material with a wall thickness of (2) The heat insulating structure according to claim 1, wherein the knitted or woven body comprises an inner layer portion with small gaps between fibers and an outer layer portion with large gaps between fibers. (3) The heat insulating structure according to claim 1, which has a metal reinforcing portion formed by casting on the outer peripheral surface of the knitted or woven body.