Methods, compositions and apparatus for stripping non-metallic inorganic coatings from metallic substrates.

Particular cleaning of specific articles is not to be classified in this subclass but in the appropriate places, e.g. B08B, F23J, F28G, F01D, F02M, F02B.

Apparatus specially adapted for cleaning metals is classified in C23G. Cleaning apparatus are classified for example in B08B.

Fouling indicating accumulation of particulates of microorganisms of the surface is classified in B08B 17/00.

Methods for etching metallic materials are classified in C23F and methods for cleaning or pickling metallic material by chemical means (no attack or removal or dissolution of metal) are classified in C23G.

If a composition is used for specific cleaning or polishing a metallic surface, it will be classified in C23G (cleaning) or C23F 3/00 (brightening).

Compositions for polishing and cleaning metallic surfaces are classified in C09G and in C23F.

Methods and compositions for pickling and brightening metallic surfaces are classified in C23G and C23F.

Methods and compositions for pickling and passivating metallic surfaces are classified in C23F and C23C 22/00.

Cleaning with azeotropic mixtures is classified in C11D and receives an additional classification symbol in C23G for specific examples concerning azeotropic cleaning mixtures for cleaning metals.

Scale concerning "white rust", "staining", "incrustation", "carbonate, sulphate, sulphide, silicate, oxalate scale" or "hydrocarbon scale" is classified in C23F 14/00, C23F 15/00.

This subclass (C23G) does not cover methods, compositions and apparatus for treatment of non-metallic material.

Classification of additional information:

Well-disclosed and non-trivial aspects are classified.

Well-known (trivial) aspects or features are not classified.

Subgroups and head groups:

Apparatus is classified in the groups or subgroups for apparatus, if such groups or subgroups exist, if not the apparatus is classified in the head group.

Cleaning or pickling/de-greasing compositions are classified in the specific subgroups according to the intrinsic nature/function of the mixture or composition, e.g. acidic aqueous cleaning or pickling composition (C23G 1/02) or alkaline aqueous cleaning or pickling compositions (C23G 1/14).

An "application-oriented" invention should be classified in an application-oriented place (when it exits). An "application-oriented" invention is considered as:

If a document concerns embodiments which are covered by several subgroups (e.g. C23G 1/061 - C23G 1/068) dependent on a higher hierarchy group (head group, e.g. C23G 1/06), the following rules apply:

For example:

If a document discloses an acidic cleaning or pickling composition comprising nitrogen-containing compounds and sulfur-containing compounds as organic inhibitors, and the specific technical information is relevant for both organic inhibitors, then it is classified in both subgroups C23G 1/061 and C23G 1/065.

Methods and compositions for cleaning or pickling metallic material by chemical means, e.g. with acidic, alkaline, neutral solutions or with molten salts.

Multi-step processes for cleaning or pickling metallic material with solutions or molten salts, e.g. a two-step pickling method comprising a first treatment step with an alkaline solution and a second treatment step with an acidic solution, are classified in C23G 1/00.

C23G 1/04 relates to the cleaning or pickling metallic material with acidic solutions comprising inhibitors, e.g. inorganic inhibitors or a mixture of inorganic and organic inhibitors.

C23G 1/06 relates to the cleaning or pickling metallic material with acidic solutions comprising only organic inhibitors.

In the range C23G 1/08 - C23G 1/088 the cleaning or pickling of iron or steel with acidic compositions are classified in the last appropriate place (last place rule).

C23G 1/16 relates to the cleaning or pickling of metallic material with alkaline solutions comprising inhibitors, e.g. inorganic inhibitors or a mixture of inorganic and organic inhibitors.

C23G 1/18 relates to the cleaning or pickling of metallic material with alkaline solutions comprising only organic inhibitors.

C23G 1/26 relates to the cleaning or pickling of metallic material with neutral solutions comprising inhibitors, e.g. inorganic inhibitors or a mixture of inorganic and organic inhibitors.

C23G 1/30 relates to the cleaning or pickling of metallic material with molten salts comprising inhibitors, e.g. inorganic inhibitors or a mixture of inorganic and organic inhibitors. Only organic inhibitors are almost impossible, because they will be destroyed by the presence of molten salts. If needed this group is only used in combination with the subgroups C23G 1/32 or C23G 1/34.

Apparatus for cleaning or pickling metallic material such as pieces, wafers, or articles by chemical means, e.g. with acidic, alkaline, neutral solutions or with molten salts.

C23G 3/02 relates to apparatus for cleaning or pickling metallic wires, strips or filaments continuously with acidic, alkaline, neutral solutions or molten salts.

C23G 3/027 relates to associated apparatus for pretreating or after-treating metallic wires, strips or filaments continuously with solutions or molten salts.

C23G 3/04 relates to apparatus for cleaning or pickling pipes with acidic, alkaline, neutral solutions or molten salts.

Other methods, compositions and apparatus for non-mechanical cleaning or de-greasing metallic material, e.g. by using gases, ion beams, plasma, freezing or cooling, supercritical fluids, melts (applying a coating which is a fondant for another coating), ultrasonics, by removing liquid contaminants by suction, by using reactive solids, followed by heating, two-phase cleaning mixtures, e.g. air under pressure in combination with an aqueous solution.

C23G 5/00 relates to other methods, compositions and apparatuses for non-mechanical cleaning or de-greasing metallic material, e.g. by using:

In subgroups C23G 5/02 - C23G 5/036, cleaning with organic solvents, in the absence of an indication to the contrary, classification is made in the last appropriate place (last place rule).

In subgroups C23G 5/02 - C23G 5/036, the mixtures of organic solvents are classified according to the major component in the mixture.

The subgroup C23G 5/02854 relates to cleaning or de-greasing metallic material with organic solvents containing halogenated hydrocarbons characterised by the stabilising or corrosion inhibiting additive. The corrosion inhibiting additive is classified with the subgroups C23G 5/02858 - C23G 5/02896.

C23G 5/04 relates to apparatuses for cleaning or de-greasing metallic material with organic solvents.

C23G 5/06 relates to apparatus for cleaning or de-greasing metallic material with emulsions, e.g. aqueous emulsions.

In the subgroups of C23G 5/00 only specific examples of the use of azeotropic cleaning mixtures for cleaning metals are classified. For example, cleaning using azeotropic mixture of dichloro-pentafluoropropane and 1,1-dichloroethane is classified in C11D 7/5059, C11D 7/5081 and also in C23G 5/02851.