Praxair S.t. Technology, Inc.

Daryl Copeland

Irina Belov

Zhihong Tang

Brian D Fitzwater

Mark W Perpall

Brian Fitzwater

Hexavalent chromium-free slurry formulations which are suitable in the production of inorganic overlay coating systems are described. The formulations provide superior hot corrosion and high-temperature oxidation protection for superalloy substrates. A basecoat slurry and topcoat slurry are provided. The basecoat slurry includes an aluminum phosphate based aqueous solution having a molar ratio of Al:P higher than about 1:3 with the incorporation of pigments of either metallic particles, or metal oxide particles, or both in combination. The topcoat slurry includes an aluminum phosphate based aqueous solution having a molar ratio of Al:P higher than about 1:3. An inorganic overlay coating formed on substrate made from the slurry formulation of present invention for hot corrosion protection on superalloy substrate against hot corrosion. Furthermore, a multilayer coating comprises a metallic bond coat and an inorganic overlay coating formed on superalloy substrate to further enhance high-temperature oxidation and hot corrosion protection.

Chromate-free inorganic coating systems for hot corrosion protection of superalloy substrate

Hexavalent chromium-free slurry formulations which are suitable in the production of ceramic overlay coating systems are described. The formulations provide superior hot corrosion and heat oxidation protection for superalloy substrates. A basecoat slurry and topcoat slurry are provided. The basecoat slurry includes an aluminum phosphate based aqueous solution having a molar ratio of Al:POhigher than about 1:3 with the incorporation of metal oxide particles. The topcoat slurry includes an aluminum phosphate based aqueous solution having a molar ratio of Al:POhigher than about 1:3. Both of the basecoat slurry and the topcoat slurry are hexavalent chromium-free.

Chromate-free ceramic coating compositions for hot corrosion protection of superalloy substrates

A composition based on a certain chromium-free silicate-based binder is described. The composition is an aqueous solution of lithium-doped potassium silicate in combination with an aluminum or aluminum alloy powder, zinc powder or a combination thereof. The coatings of the present invention are capable of achieving a full cure at temperatures as low as 350-450 degrees F. by the inclusion of a colloidal solution of a nano-sized ceria, thus making the coatings especially suitable for application on temperature sensitive base materials.

Chromium-free silicate-based ceramic compositions with reduced curing temperature

A novel chromate-free multi-layer coating system composed of a lithium-doped potassium silicate binder based basecoat composition that is sealed with an aluminum phosphate-based top coat composition is described. The multi-layer coating system exhibits superior corrosion and heat oxidation resistance which can replace traditional chromate-containing coating systems.

Chromate-free ceramic coating compositions

A composition based on a certain chromium-free silicate-based binder is described. The one-part slurry composition is an aqueous solution of lithium-doped potassium silicate in combination with an aluminum or aluminum alloy powder. The one-part slurry composition produces a corresponding coating exhibiting improved performance at a reduced coating thickness.

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Greenwood, IN, United States of America

Daryl Copeland