Title of Invention	"AN IMPROVED PROCESS FOR THE PREPARATION OF OXIDE COATED ALUMINIUM AND ITS ALLOYS"
Abstract	An improved process for the preparation of oxide coated aluminium or its alloys by polishing, degreasing and cleaning the aluminium or aluminium alloy to be coated by conventional method, desmutting in nitric acid and followed by washing, subjecting it to anodic coating using sulphamic acid in the concentration range of 10 to 15% w/v as electrolyte using graphite as cathode at 30° to 40°C using pulse current, recovering the oxide coated aluminium/aluminium ally after washing and drying the substrate.

Title of Invention

"AN IMPROVED PROCESS FOR THE PREPARATION OF OXIDE COATED ALUMINIUM AND ITS ALLOYS"

Abstract

An improved process for the preparation of oxide coated aluminium or its alloys by polishing, degreasing and cleaning the aluminium or aluminium alloy to be coated by conventional method, desmutting in nitric acid and followed by washing, subjecting it to anodic coating using sulphamic acid in the concentration range of 10 to 15% w/v as electrolyte using graphite as cathode at 30° to 40°C using pulse current, recovering the oxide coated aluminium/aluminium ally after washing and drying the substrate.

Full Text	aggressive electrolyte and can form oxide coating on aluminium and its alloys at ambient temperature of 30° to 40°C with sufficiently thick hard compact film using pulse current of a programmable high power pulse source. The main object of the present invention is to provide an improved process for the preparation of oxide coated aluminium or its alloys. Another object of the present invention is to develop a process for anodic coating of aluminium and its alloys with sulphamic acid as an electrolyte using pulsed current. A PC based power source delivers pulse current with all essential pulse parameters such as on/off time ranging from 1 sec. to 100 sees, on/off current amplitude ranging from 0 to 10 amps, experimental duration from 1 minutes to 60 minutes. The new result achieved from the present invention is a thick compact hard anodic coating on aluminium and its alloys especially on difficult to anodising alloys containing more than 2% up to 5% copper. Accordingly, the present invention provides an improved process for the preparation of oxide coated aluminium and its alloys which comprises polishing, degreasing and cleaning the aluminium or aluminium alloy to be coated by conventional method, desmutting in nitric acid and followed by washing, subjecting it to anodic coating using sulphamic acid in the concentration range of 10 to 15% w/v as electrolyte using graphite as cathode at 3 0 to 40 C using pulse current such as herein described for 40 to 60 minutes, recovering the oxide. We claim 1. An improved process for the preparation of oxide coated aluminium or its alloys which comprises polishing, degreasing and cleaning the aluminium or aluminium alloy to be coated by conventional method, desmutting in nitric acid and followed by washing, subjecting it to anodic coating using sulphamic acid in the concentration range of 10 to 15% w/v as electrolyte using grapfa- ite as cathode at 30° to 40°C such as herein describes for 40 to 60 minutes, recovering the oxide coated aluminium/aluminium alloy after washing and drying the substrate. 2.An improved process as claimed in claims (1), wherein the pulse average current density of 1 to 1.5 A/sq.dm. with on/off time in the range of 1 sec to 100 secs. 3. An improved process for the preparation of oxide coated aluminium or its alloys as here in described with refenence to the examples.

Full Text

aggressive electrolyte and can form oxide coating on
aluminium and its alloys at ambient temperature of 30° to 40°C
with sufficiently thick hard compact film using pulse current of
a programmable high power pulse source.
The main object of the present invention is to provide an improved process for the preparation of oxide coated aluminium or its alloys.
Another object of the present invention is to develop a process for anodic coating of aluminium and its alloys with sulphamic acid as an electrolyte using pulsed current. A PC based power source delivers pulse current with all essential pulse parameters such as on/off time ranging from 1 sec. to 100 sees, on/off current amplitude ranging from 0 to 10 amps, experimental duration from 1 minutes to 60 minutes.
The new result achieved from the present invention is a thick compact hard anodic coating on aluminium and its alloys especially on difficult to anodising alloys containing more than 2% up to 5% copper.
Accordingly, the present invention provides an improved process for the preparation of oxide coated aluminium and its alloys which comprises polishing, degreasing and cleaning the aluminium or aluminium alloy to be coated by conventional method, desmutting in nitric acid and followed by washing, subjecting it to anodic coating using sulphamic acid in the concentration range of 10 to 15% w/v as electrolyte using graphite as cathode at 3 0 to 40 C using pulse current such as herein described for 40 to 60 minutes, recovering the oxide.

We claim
1. An improved process for the preparation of oxide coated aluminium or its alloys which comprises polishing, degreasing and cleaning the aluminium or aluminium alloy to be coated by conventional method, desmutting in nitric acid and followed by washing, subjecting it to anodic coating using sulphamic acid in the
concentration range of 10 to 15% w/v as electrolyte using grapfa- ite as cathode at 30° to 40°C such as herein describes
for 40 to 60 minutes, recovering the oxide coated aluminium/aluminium alloy after washing
and drying the substrate.
2.An improved process as claimed in claims (1), wherein the pulse average current density of 1 to 1.5 A/sq.dm. with on/off time in the range of 1 sec to 100 secs.
3. An improved process for the preparation of oxide coated aluminium or its alloys as here in described with refenence to the
examples.

Documents:

377-del-1998-abstract.pdf

377-del-1998-claims.pdf

377-del-1998-complete specification (granted).pdf

377-del-1998-correspondence-others.pdf

377-del-1998-correspondence-po.pdf

377-del-1998-description (complete).pdf

377-del-1998-form-1.pdf

377-del-1998-form-19.pdf

377-del-1998-form-2.pdf

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Patent Number

194981

Indian Patent Application Number

377/DEL/1998

PG Journal Number

51/2004

Publication Date

18-Dec-2004

Grant Date

17-Mar-2006

Date of Filing

13-Feb-1998

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110 001, INDIA

Inventors:

#	Inventor's Name	Inventor's Address
1	DEVARAJ KANAGARAJ	SCIENTIST CENTRAL ELECROCHEMICAL RESEARCH INSTITUTE, KARAIKUDI 630006,
2	SYSAI VINCENT	TECHNICAL OFFICER, CENTRAL ELECROCHEMICAL RESEARCH INSTITUTE, KARAIKUDI 630006,
3	VENGNANARAYANAN MAHADEV IYER	SCIENTIST, CENTRAL ELECROCHEMICAL RESEARCH INSTITUTE, KARAIKUDI 630006,
4	VENKATASUBRAMANIAN LAKSHMI NARSIMHAN	SCIENTIST, CENTRAL ELECROCHEMICAL RESEARCH INSTITUTE, KARAIKUDI 630006,
5	JEEVARATHINAM KENNEDY	TECHNICAL ASSISTANT, CENTRAL ELECROCHEMICAL RESEARCH INSTITUTE, KARAIKUDI 630006,

PCT International Classification Number

B05D 1/24

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA