Non-toxic corrosion resistant conversion coating for aluminum and aluminum alloys and the process for making the same
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United States of America Patent
Stats
-
Mar 21, 1995
Issued Date -
N/A
app pub date -
Feb 3, 1993
filing date -
Sep 3, 1991
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A non-toxic corrosion resistant conversion coating for aluminum is formed by a process which includes subjecting the aluminum to an acidic aqueous solution containing potassium permanganate and cerous chloride, alone or in combination with strontium chloride. The corrosion resistance is improved by a subsequent treatment in an alkaline solution containing molybdate, nitrite and metasilicate ions. The corrosion resistant is further improved by treating the coated surface with an acholic solution containing glycidoxy(epoxy)polyfunctionalmethoxysilane, alone or in combination with phenyltrimethoxysilane. The coating thus produced is a mixture of oxides and hydroxides of cerium strontium and aluminum. These oxides and hydroxides may also be intermixed with molybdate silicate and nitrite ions. In the most corrosion resistant form the mixture further includes a silane overcoat.
First Claim
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