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US 4,798,770 AGranted
Heat resisting and insulating light alloy articles and method of manufacture
AssigneeToyota Jidosha Kabushiki Kaisha
InventorsTadashi Donomoto, Mototsugu Koyama, Masaaki Nagaoka
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Abstract
Light alloy articles comprising a body of light alloy having a composite fiber/light alloy layer, a sprayed heat-resistant alloy layer, and a sprayed ceramic base layer formed on the body in this sequence exhibit improved heat resistance and insulation and are very useful in the manufacture of internal combustion engine pistons. A method for producing such a coated light alloy article by spraying is also provided.
Claims14
A heat-resisting and insulating light alloy article, comprising:
- (a) a body of a light alloy selected from the group consisting of aluminum alloys and magnesium alloys,
- (b) a composite fiber/light alloy layer formed on the body, wherein the composite layer is made essentially of a light alloy of the same type as the light alloy of which the body is made and heat-resistant fibers having a lower heat conductivity than the light alloy, said fibers being integrally bonded by the light alloy and being selected from the group consisting of Al.sub.2 O.sub.3 fibers, ZrO.sub.2 fibers, SiC fibers, Al.sub.2 O.sub.3 -SiO.sub.2 fiber, glass fibers, carbon fibers, boron fibers, stainless steel fibers, SiC whiskers, Si.sub.3 N.sub.4 whiskers, and potassium titanate whiskers,
- (c) a first layer of a heat-remaining alloy sprayed onto said composite layer, which alloy is selected from the group consisting of Ni-Cr alloy, Ni-Cr-Al alloy and Ni-Cr-Al-Y alloy, and
- (d) a second layer of a ceramic base material sprayed onto said first layer, which material is selected from the group consisting of ZrO.sub.2, Al.sub.2 O.sub.3, MgO, Cr.sub.2 O.sub.3, and mixtures thereof, and wherein the heat-resisting alloy, of which the first layer is made, has a thermal expansion coefficient which is higher than the ceramic material of said second layer, but lower than the composite fiber/light alloy layer.
1 more element
A method for producing a heat resisting and insulating light-alloy article comprising the steps of
- placing a preform of heat-resistant fibers at a given position in a cavity of a mold,
- pouring a molten light alloy into the mold cavity,
- subjecting the molten light alloy in the mold cavity to liquid metal forging, thereby causing the light alloy to fill up the space among the fibers of the preform
- allowing the light alloy to solidify to form a block of the light alloy having a composite fiber/light alloy layer integrated on its surface,
- removing the block from the mold,
- spraying a heat-resisting alloy onto the composite fiber/light alloy layer on the block, and
- further spraying a ceramic base material onto the sprayed layer of the heat-resisting alloy.
4 more elements
Dependencies are inferred from the claim text.