摘要:
The invention relates to a method for production of thermal insulation layers which adhere better to components even at high, frequently changing temperatures. A gas-tight glass-metal composite layer is applied to the component and aged. The corroded part of the gas-tight layer is then removed and a second porous layer applied which can be made from a ceramic material in particular, an yttrium-stabilised zirconium oxide. The invention further relates to a thermal insulation layer which is made up of a sandwich of a gas-tight glass-metal composite layer and a superimposed further porous layer. As a result of the boundary volumes of the composite layer with the further layer being partly crystalline the adhesion within the sandwich is markedly improved with relation to the prior art. It is thus possible to produce a sandwich of silicate glass- metal composite layers and yttrium-stabilised zirconium oxide which is stable to heat over a long period of time. Such a sandwich is particularly useful for application as thermal insulation layer due to combining good oxidation protection with a low heat conductivity and low susceptibility to aging.
摘要:
The invention relates to a method for producing gas-tight layers and layer systems by means of a thermal spraying method. A layer is firstly applied by thermal spraying using a burner and is subjected to a subsequent thermal treatment by the same burner. This interruption-free method makes possible a simple and cost-effective production of gas-tight layers and layer systems having good adhesive properties. The method is particularly suited for producing fuel cell structures due to the fact that a gas-tight layer can be placed at any location in a layer system.
摘要:
Only mullite, yttrium silicate and zirconium do not have sufficient protection against oxidation at high temperatures when they are used as protective layers for non-oxidic ceramics containing Si. A covering layer arranged thereon and known according to prior art for metallic substrates is generally unsuitable due to its thermal expansion coefficient and/or its chemical incompatibility as thermally induced stresses are created, leading to cracks and flaking of the covering layer. The invention relates to a protective layer system for a non-oxidic ceramic containing Si, said system comprising a first protective layer provided with an oxide containing Si, and a covering layer arranged on the protective layer. Said covering layer contains a compound which is impermeable to oxygen and has a thermal expansion coefficient of less than 9,0*10-6/K. One such protective layer system is suitable both as a heat insulating layer and as an anti-corrosion layer against oxygen and water vapour. Said layers can advantageously be embodied in an at least partially graduated manner. The combination of a mullite protective layer and a lanthanum hafnate or a hafniumorthosilicate covering layer has proven to be especially advantageous.
摘要:
The invention relates to a heat insulating layer on a metallic substrate for using for high temperatures, especially for temperatures above 1300 °C. Starting with a base of La2Zr2O7, the properties of the heat insulating substance to be used as the heat insulating layer are regularly improved, by substituting lanthanum cations with ions of elements Nd, Eu, Dy, Sm and/or Gd. An additional, at least partial substitution of the zirconium cations by Ce, Hf or Ta is advantageous. Improving the properties results especially in a high thermal coefficient of dilation α and low heat conductivity λ.
摘要:
The invention relates to a material, in particular for a thermal insulation layer, with increased thermal stability, a low heat conductivity and a large thermal coefficient of expansion. According to the invention, said material comprises lanthanides, in particular the elements La, Ce, Nd, Yb, Lu, Er or Tm, which preferably occur as a mixture in a Perovskite structure. Said thermal insulation layer is particularly suitable for replacing thermal insulation layers comprising yttrium stabilised zirconium oxides (YSZ) as the thermal stability thereof is given as well over 1200 °C.