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Vacuum Clading of Aluminum Castings to Enhance Hard Anodize Surface Finish

IP.com Disclosure Number: IPCOM000060102D
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Wirsing, CE: AUTHOR

Abstract

Core aluminum is an A356 alloy which has 7% silicon by weight to enhance fluidity during casting. After casting, the workpiece is anodized in an electrolytic cell (hard coating) to form a 0.001 inch coat of Al203 . Since silicon is not anodized in the cell, the silicon microcrystallites remain in place on (and just beneath) the surface of the casting, thereby creating a resultant rough surface after the anodizing steps. This rough surface has a reduced conductive heat transfer characteristic when the workpiece is abutted against another structure.

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Vacuum Clading of Aluminum Castings to Enhance Hard Anodize Surface Finish

Core aluminum is an A356 alloy which has 7% silicon by weight to enhance fluidity during casting. After casting, the workpiece is anodized in an electrolytic cell (hard coating) to form a 0.001 inch coat of Al203 . Since silicon is not anodized in the cell, the silicon microcrystallites remain in place on (and just beneath) the surface of the casting, thereby creating a resultant rough surface after the anodizing steps. This rough surface has a reduced conductive heat transfer characteristic when the workpiece is abutted against another structure.

This problem is overcome by plating (vacuum evaporation) a layer of 99.99% pure aluminum (approximately 0.001") onto the aluminum workpiece surface. Thereafter, when the aluminum plated workpiece is anodized, the resultant surface is smooth and has a high heat transfer characteristic.

Disclosed anonymously.

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