Stock material or miscellaneous articles – All metal or with adjacent metals – Composite; i.e. – plural – adjacent – spatially distinct metal...
Patent
1984-08-27
1987-12-22
Rutledge, L. Dewayne
Stock material or miscellaneous articles
All metal or with adjacent metals
Composite; i.e., plural, adjacent, spatially distinct metal...
428682, 428683, 428684, 428679, 22826315, B32B 1500
Patent
active
047146591
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a thermal protective shield to be used for hot gases in machinery. Primarily, the invention refers to a flame protective shield to be used in connection with the combustion of solid, liquid or gaseous fueld. Other possible fields of application are e.g. in Stirling engines driven by solar energy. The invention also relates to a method of manufacturing such a thermal protective shield and the use of the same in the special application constituted by a Stirling engine. As is recognized in the art, a Stirling engine is an external combustion engine in which heat released from burning fuel is transferred to a confined gas which activates pistons.
Thermal protective shields of different kinds are used in connection with combustion for various purposes. The necessity of special thermal protective shields appears only at the highest temperatures occuring in connection with combustion. When developing new engine types and improving known types for achieving higher efficiency, there is also a desire to increase the working temperatures and thus the temperature of the materials used. In addition to the temperature, a flame protective shield must resist the influence of combustion gases and, in certain applications, meet the requirements of mechanical strength. The term flame protection does not imply that the shield should be directly exposed to a flame resulting from the combustion. In many applications, the major part of the transfer of heat to the protective shield is constituted by radiation. In other applications, the transfer of heat is entirely effected by radiation, e.g. in case of collecting solar energy.
A plurality of different materials for heat shields have been tested previously and even found a certain use. Among these materials, various high temperature resistant alloys could be mentioned, which alloys are usually based on nickel or cobalt. As far as these material have met the technological requirements, however, it has turned out that these materials are expensive and in many cases difficult to obtain. Therefore, they are not suitable for mass production.
In trying to avoid the above-mentioned difficulties in connection with high temperature resistant alloys, materials consisting of several layers have been tested. A material, which is satisfactory from the mechanical point of view, has been coated on the side to be facing the combustion chamber or the like with a ceramic, high temperature resistant material. The coating is applied by thermal spraying, e.g. flame spraying or plasma spraying. As an example of coating materials zirconium oxide can be mentioned. In connection with these multi-layer materials, however, problems have arisen, primarily due to the different thermal expansion coefficients of the substrate and the coating. This may result either in crack formations in the coating material or in a tendency of the coating to loosen entirely or partly from the substrate. The problems have been increased in that, due to the high temperature in the combustion chamber and the relatively bad characteristics of the substrate at high temperatures, the coatings are necessarily made relatively thick.
The present invention concerns a thermal protective material consisting of several layers of such a kind that the above-mentioned problems are avoided, whereas satisfactory mechanical and physical characteristics are obtained. According to the invention, the thermal protective shield comprises at leasat two layers, wherein the outer layer facing the hot gases in the combustion chamber or the like consists of an alloy of the iron-chrome-aluminium-type. The latter is connected over a surface fully corresponding to the surface exposed to the combustion gases, to another material having sufficient mechanical characteristics at high temperatures to meet the requirements of the thermal protective shield. The material is produced by connecting two shields so as to avoid enclosed oxides and pores being obtained to a great extent when coating by means of thermal spraying. By produc
REFERENCES:
patent: 3343928 (1967-07-01), Bellis et al.
patent: 3861146 (1975-01-01), Lynch et al.
patent: 4034142 (1977-07-01), Hecht
patent: 4144380 (1979-03-01), Beltran et al.
patent: 4172363 (1979-10-01), Bex
patent: 4198442 (1980-04-01), Gupta et al.
Anderson Bjorn
Lindgren Hakan
Bulten-Kanthal AB
Rutledge L. Dewayne
Yee Deborah
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