US4851148A
Expired / Lapsed
US
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Method of controlling an aluminum surface cleaning composition
Assignee: Henkel Corp
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Filing: 1986-04-03
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Granted: 1989-07-25
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Expires: 2006-04-03
Abstract
Abstract In chromium-free aqueous acidic washing solutions for cleaning the surfaces of aluminum and aluminum-alloy particles, so as to remove therefrom smut and lubricating oil left on the surfaces thereof after metal forming operations, which solutions contain from 0.2 to 4 g/l ferric ion and sufficient sulfuric and/or nitric acid to impart a pH of 2 or less to the solutionh (and which optionally may also contain fluoride ions up to a concentration of 0.5 g/l) there is provided a method of controlling the effectiveness of the washing solution in which the ferric ion concentration therein is monitored, conveniently by the oxidation-reduction potential of the washing solution, as shown in FIG. 3, and is controlled within the desired limits by adding when appropriate suitable amounts of oxidant capable of oxidizing ferrous ions to ferric ions and, separately or in conjunction therewith, a replenisher containing a source of iron ions.
Inventors
- 👤 Katsuyoshi Yamasoe
- 👤 Satoshi Ikeda
- 👤 Kiyotada Yasuhara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 14:59
CPC Classifications
C; C23; C23G; C23G1/00; C23G1/02; C23G1/12; C23G1/125
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
152 words
In a process for cleaning an aluminum surface comprising the steps of a. contacting said aluminum surface with a chromium-free acidic aqueous cleaning solution consisting of from about 0.2 to about 4 g/l of ferric ions, a quantity of sulfuric and/or nitric acid to provide a pH for the cleaning solution of 2.0 or less, and up to 0.5 g/l of fluoride ions; the improvement comprising: b. monitoring the ferric ion concentration in the cleaning solution; c. when the ferric ion concentration falls below a predetermined level, restoring the ferric ion concentration to at least said predetermined level by adding to the cleaning solution an oxidant compatible with a clean aluminum surface in an amount sufficient to oxidize ferrous ions present in the cleaning solution to ferric ions; and d. replenishing the iron ion concentration in the cleaning solution as needed by the addition thereto of at least one water-soluble iron compound.
Claim 2
Dependent Claim
152 words
In a process for cleaning an aluminum surface comprising the steps of a. contacting said aluminum surface with a chromium-free acidic aqueous cleaning solution consisting of from about 0.2 to about 4 g/l of ferric ions, a quantity of sulfuric and/or nitric acid to provide a pH for the cleaning solution of 2.0 or less, and up to 0.5 g/l of fluoride ions; the improvement comprising: b. monitoring the ferric ion concentration in the cleaning solution; c. when the ferric ion concentration falls below a predetermined level, restoring the ferric ion concentration to at least said predetermined level by adding to the cleaning solution an oxidant compatible with a clean aluminum surface in an amount sufficient to oxidize ferrous ions present in the cleaning solution to ferric ions; and d. replenishing the iron ion concentration in the cleaning solution as needed by the addition thereto of at least one water-soluble iron compound.
Claim 3
Dependent Claim
14 words
In a process according to claim 1 wherein the cleaning solution is substantially fluoride-free.
Claim 4
Dependent Claim
28 words
In a process according to claim 1 wherein in step b. the ferric ion concentration is monitored by a measurement of the oxidation-reduction potential of the cleaning solution.
Claim 5
Dependent Claim
26 words
In a process according to claim 1 wherein in step c. the oxidant is one or more of a peroxide, nitrite, peroxosulfate, metavanadate or cerium compound.
Claim 6
Dependent Claim
27 words
In a process according to claim 4 wherein the oxidant is one or more of hydrogen peroxide, sodium nitrite, sodium peroxosulfate, ammonium metavanadate, and cerium ammonium sulfate.
Claim 7
Dependent Claim
23 words
In a process according to claim 1 wherein in step d. the water-soluble iron compound is selected from ferric sulfate and ferric nitrate.
Claim 8
Dependent Claim
31 words
In a process according to claim 1 wherein in step a. the ferric ions are present in the form of one or more of ferric sulfate, ferric nitrate, and ferric chlorate.
Claim 9
Dependent Claim
28 words
In a process according to claim 1 wherein in step a. the cleaning solution also contains from about 0.5 to about 4 g/l of a surface active agent.
Claim 10
Dependent Claim
19 words
In a process according to claim 1 wherein in step a. the cleaning solution also contains a chelating agent.
Claim 11
Dependent Claim
23 words
In a process according to claim 9 wherein the chelating agent is one or more of citric acid, oxalic acid, and tartaric acid.
Claim 12
Dependent Claim
34 words
In a process according to claim 1 wherein in step a. said contacting is carried out by immersion or spray at a temperature within the range of about 20° C. to about 80° C.
Claim 13
Dependent Claim
31 words
In a process according to claim 1 wherein in step c. the predetermined level of ferric ion is a quantity within the range of from about 0.2 to about 4 g/l.
Claim 14
Dependent Claim
46 words
In a process according to claim 1 including monitoring the pH of the solution and when the pH is greater than about 2.0, a quantity of sulfuric and/or nitric acid is added to the bath to lower the pH to between about 0.6 and about 2.0.
Claim 15
Dependent Claim
34 words
In a process according to claim 1 wherein in step d. the water-soluble iron compound is a ferrous compound which is added together with sufficient oxidant to oxidize the ferrous ions to ferric ions.
Claim 16
Dependent Claim
50 words
In a process according to claim 1 including monitoring the pH of the solution and when the pH is greater than a predeterminal pH level below 2.0, a quantity of sulfuric and/or nitric acid is added to the bath to lower the pH to between about 0.6 and about 2.0.
Claim 17
Dependent Claim
120 words
In a process for cleaning an aluminum surface comprising the steps of a. contacting said aluminum surface with a chromium-free acidic aqueous cleaning solution consisting of from about 0.2 to about 4 g/l of ferric ions, a quantity of sulfuric and/or nitric acid to provide a pH for the cleaning solution of 2.0 or less, and up to 0.5 g/l of fluoride ions; the improvement comprising: b. maintaining in the cleaning solution an oxidant compatible with a clean aluminum surface in an amount sufficient to oxidize ferrous ions present in the cleaning solution to ferric ions; and c. replenishing the iron ion concentration in the cleaning solution as needed by the addition thereto of at least one water-soluble iron compound.
Claim 18
Dependent Claim
120 words
In a process for cleaning an aluminum surface comprising the steps of a. contacting said aluminum surface with a chromium-free acidic aqueous cleaning solution consisting of from about 0.2 to about 4 g/l of ferric ions, a quantity of sulfuric and/or nitric acid to provide a pH for the cleaning solution of 2.0 or less, and up to 0.5 g/l of fluoride ions; the improvement comprising: b. maintaining in the cleaning solution an oxidant compatible with a clean aluminum surface in an amount sufficient to oxidize ferrous ions present in the cleaning solution to ferric ions; and c. replenishing the iron ion concentration in the cleaning solution as needed by the addition thereto of at least one water-soluble iron compound.
Claim 19
Dependent Claim
14 words
In a process according to claim 16 wherein the cleaning solution is substantially fluoride-free.
Claim 20
Dependent Claim
26 words
In a process according to claim 16 wherein in step b. the oxidant is one or more of a peroxide, nitrite, peroxosulfate, metavanadate or cerium compound.
Claim 21
Dependent Claim
27 words
In a process according to claim 18 wherein the oxidant is one or more of hydrogen peroxide, sodium nitrite, sodium peroxosulfate, ammonium metavanadate, and cerium ammonium sulfate.
Claim 22
Dependent Claim
23 words
In a process according to claim 16 wherein in step c. the water-soluble iron compound is selected from ferric sulfate and ferric nitrate.
Claim 23
Dependent Claim
31 words
In a process according to claim 16 wherein in step a. the ferric ions are present in the form of one or more of ferric sulfate, ferric nitrate, and ferric chlorate.
Claim 24
Dependent Claim
28 words
In a process according to claim 16 wherein in step a. the cleaning solution also contains from about 0.5 to about 4 g/l of a surface active agent.
Claim 25
Dependent Claim
19 words
In a process according to claim 16 wherein in step a. the cleaning solution also contains a chelating agent.
Claim 26
Dependent Claim
23 words
In a process according to claim 23 wherein the chelating agent is one or more of citric acid, oxalic acid, and tartaric acid.
Claim 27
Dependent Claim
34 words
In a process according to claim 16 wherein in step a. said contacting is carried out by immersion or spray at a temperature within the range of about 20° C. to about 80° C.
Claim 28
Dependent Claim
46 words
In a process according to claim 16 including monitoring the pH of the solution and when the pH is greater than about 2.0, a quantity of sulfuric acid/or nitric acid is added to the bath to lower the pH to between about 0.6 and about 2.0.
Claim 29
Dependent Claim
34 words
In a process according to claim 16 wherein in step c. the water-soluble iron compound is a ferrous compound which is added together with sufficient oxidant to oxidize the ferrous ions to ferric ions.
Claim 30
Dependent Claim
50 words
In a process according to claim 16 including monitoring the pH of the solution and when the pH is greater than a predetermined pH level below 2.0, a quantity of sulfuric and/or nitric acid is added to the bath to lower the pH to between about 0.6 and about 2.0.
References Cited (Backward Citations)
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