Hot-dipping or immersion processes and apparatus for applying the coating material in the molten state without affecting the shape.

Coating by spraying, casting, by vacuum evaporation, by sputtering or by ion implantation and the different aspects of chemical coating which includes

Chemical coating by decomposition of either gaseous compounds, liquid or solid compounds, solutions or suspensions of the coating forming compounds, without leaving reaction products of surface material in the coating.

Coating starting from inorganic powder.

Coating with metallic material characterized only by the composition of the metallic material.

Chemical surface treatment of metallic materials, leaving reaction products of surface material in the coating.

All coatings referred to in this subclass are either "for metallic materials" or "by metallic material," with the exception of PVD (by vacuum evaporation, by sputtering or by ion implantation), and CVD (an aspect included in "the different aspects of chemical coating").

Solid state diffusion into metallic material surfaces.

Applying liquids or other fluent materials to surfaces in general are classified in B05; while C23C includes the coating of metallic material and the coating material with metallic material.

Making metal-coated products by extrusion is classified in B21C 23/22 while C23C includes surface treatment of metallic material by diffusion into the surface.

Metallizing of glass is classified in C03C and Metallizing mortars, concrete, artificial stone, ceramics or natural stone is classified in C04B 41/00.

Coating with paints, varnishes, lacquers is classified in C09D.

Covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D 39/00, B23K.

Processes for the electrolytic or electrophoretic production of coatings are classified in C25D.

Processes for the electrolytic removal of materials from objects are classified in C25F.

Enameling of or applying a vitreous layer to, metals is classified in C23D.

Inhibiting corrosion of metallic material or incrustation in general is classified in C23F.

Cleaning or de-greasing of metallic material by chemical methods other than electrolysis, e.g. cleaning, pickling are classified in C23G

In this subclass, an operation is considered as pretreatment or after-treatment when it is specially adapted for, but quite distinct from, the coating process concerned and constitutes an independent operation. If an operation results in the formation of a permanent sub-layer or upper layer, it is considered as pre-treatment or after-treatment only if it has a direct impact on the layer above or below respectively.

Metallic coatings obtained by dipping or immersing a substrate into a molten bath of the coating material, where the substrate itself remains essentially unchanged, as well as any methods and/or apparatuses specifically used thereof.

Enameling of, or applying a vitreous layer to metals is classified in C23D 5/00.

Formation of mono or polycrystalline Si coatings by pulling high temperature resistant wires and/or sheets through molten silicon is classified in C30B 29/06.

Single-crystal growth by pulling from a melt, pulling on a substrate C30B 15/007.

Production of homogeneous polycrystalline material with defined structure, from liquids, by pulling from a melt C30B 28/10.

Classification is given to well disclosed coatings and/or processes. Classification is further given to related processes, such as pre-treatment(s) of the substrate or after-treatment(s) of the coating. Classification is also further given to apparatus features important to the coating process.

In this main group, an operation is considered as pre-treatment or after-treatment when it is specially adapted for, but quite distinct from, the coating process concerned and constitutes an independent operation.

All well-disclosed, non-trivial examples of processes and/or coatings are classified. Precedence rules indicated in the headers of the subgroups are to be strictly followed, e.g. removal by air knives of an excess of molten material on a strip is to be classified only in C23C 2/20, and not also in C23C 2/26 and C23C 2/40.

Alloys based on a given metal are alloys where said metal makes up at least 50% by weight of said alloy (see in particular C23C 2/06, C23C 2/08, C23C 2/10 and C23C 2/12).

Magnetic energy being applied to the system is classified based upon the intended effect of the magnetic energy on the system.

C23C 2/00362 covers the use of magnetic energy to effect sealing or otherwise containing the molten material within the container at an opening in the wall which the substrate travels.

C23C 2/24 covers the use of magnetic or electric fields energy to remove excess molten coating or to otherwise control the thickness of the coating applied to the substrate after the substrate exits the coating bath.

C23C 2/32 covers the use of magnetic energy to cause vibrations of the liquid metal in the bath for stirring purposes etc. or the substrate while in the molten bath.

C23C 2/5245 covers the use of magnetic energy to reduce vibrations of the substrate travelling through the bath.

Elements that are immersed within the bath, such as walls, baffles, pumps, elements supporting the substrate during coating or elements for moving the substrate through the bath. Non-moving immersed elements are classified here.

Elements that are immersed within the bath which are in motion relative to the bath, such as pumps (i.e. the internal impeller moves relative to the bath), mixers, impellers, rollers or bearings.

Devices for mixing or stirring of the bath with control or regulation should also be classified in C23C 2/54, C23C 2/542 or C23C 2/544 as appropriate.

Elements that are immersed within the bath and act to force movement of the substrate through the bath, such as rollers or portions thereof, e.g. bearings.

Elements that act upon the substrate to be coated to move the substrate through the bath, such as take-up rollers or supply rollers.

Crucibles and heating devices. This area also covers the vessel for a holding bath.

Pre-treatment chamber(s), and elements thereof, that are directly associated with the hot-dipping or immersion apparatus, such as specific structure of pretreatment chamber(s), chamber mechanisms, transportation mechanism, seals, or heat or atmospheric conditions.

Fixed enclosures between the furnace and the molten metal bath.

Processes or devices for conducting patterned or selective deposition on the substrate.

Methods or devices for forming patterned or selective deposition by means external to the substrate, e.g. using masking elements such as casings, shields, fixtures or blocking elements.

Pattern or selective deposition done by means of applying a masking layer to the substrate.

Pre-treatment of the material to be coated, an operation being considered as pre-treatment when it is specially adapted for, but quite distinct from, the coating process concerned and constitutes an independent operation.

For example:

For pre-treatments (e.g. cold or hot rolling or heat treatments) that are covered by C21D and/or C22F, an allocation is made in both C23C 2/02 and the relevant subgroups in C21D and/or C22F.

Application of complete or partial layers onto the substrate to be coated prior to entry into the bath. Examples of these layers are adhesion layers that promote adhesion between the substrate and the bath material, pre-applied alloying elements that mix with the bath material in the coating, and layers that protect the substrate from corrosion prior to entry into the bath.

Masking layers for forming patterned or selective deposition are not considered sub-layers and are classified in C23C 2/0064.

Fluxes or covering materials for molten baths, e.g. fluxes materials used in hot dipping process

Application of vibrations using physical, magnetic or other means to the bath or to the substrate. An example of subject matter covered by this group is the use of ultrasonic energy to a substrate to cause vibrations of the substrate to enhance wettability of the substrate.

Application of vibratory energy to remove excess coating material is classified in C23C 2/14.

Processes for cleaning of the bath and the devices that perform the cleaning.

"Cleaning" is intended to cover removal, by chemical or physical means, of impurities within the bath, such as devices which skim material from the surface of the bath or which remove a portion of the bath for treatment to remove impurities before returning the treated portion to the bath.

Control or regulation of the coating process, wherein the control or regulation is performed responsive by a computer.

Examples include standard PID controllers, "fuzzy" logic controllers and artificial intelligence or machine-learning implemented control of the coating process.

This subgroup should be used in combination with any appropriate subgroups that are also indented under C23C 2/50.

Control or regulation of the coating process wherein at least one variable is measured or sensed.

"Measured or sensed" includes both electronic and mechanical detection of variables, as well as "measuring or sensing" by an operator of the coating process, such as visual inspection of the variable of the coating process.

Measuring or sensing the position of the substrate, which includes at least the location of the substrate with respect to fixed portions of the coating apparatus and any change in the location of the substrate over time, e.g. vibration of the substrate.

Using image processing techniques to investigate the surface quality of the substrate.

Methods or devices for controlling or regulating the mixing or stirring of the bath.

Devices for mixing or stirring of the bath without control or regulation are classified in C23C 2/003 or in C23C 2/00342 as appropriate.

Coating processes in which melted or partially melted materials are sprayed, i.e. propelled, onto a surface, as well as apparatuses specifically used thereof.

The material to be deposited is typically fed into the spray gun in powder, wire or rod form where it is rapidly heated and melted or partially melted by electrical (plasma or arc) or chemical means (combustion flame, detonation), before being accelerated towards the substrate to be coated.

The obtained coatings are characterized by a lamellar grain structure resulting from the rapid solidification of small globules, flattened from striking a cold surface at high velocities.

Protective layers or coatings deposited by spraying for specific articles is classified in this group and also classified in the appropriate places for said specific articles, e.g. F01D 5/288 for protective coatings for turbine blades; F28F 19/02, F28F 19/06 for protective coatings for heat exchangers; A61L 27/28 for coating materials for prostheses; B22C 3/00 for coating compositions for surfaces of moulds, cores or patterns.

Classes are given to well disclosed coatings and/or methods. Classes are further given to related methods, such as pre-treatment(s) of the substrate or after-treatment(s) of the coating. Classes are also further given to apparatus features important to the coating method.

In this main group, an operation is considered as pre-treatment or after-treatment when it is specially adapted for, but quite distinct from, the coating process concerned and constitutes an independent operation.

All well-disclosed, non-trivial examples of methods and/or coatings are classified.

Precedence rules indicated in the headers of the subgroups are to be strictly followed.

Masking elements such as casings, shields, fixtures or blocking elements.

Stripping foreign matter from cavities by means of gas or water jets.

Pre-treatment of the material to be coated, an operation being considered as pre-treatment when it is specially adapted for, but quite distinct from, the coating process concerned and constitutes an independent operation.

For example:

Only methods which are specially adapted for, but quite distinct from the main spraying coating process, and which result in sublayers having a direct impact on the main coating layer either above (e.g. adhesion) or below (e.g. masking) should be classified in this group.

Sprayed bond coats for thermal barrier coatings (TBC) are only to be classified if the TBC is also sprayed and the bond coat is well-defined and/or exhibiting unusual characteristics.

Spraying the coating material characterised by the coating composition that is not covered by the subgroups

All specific and well-defined coating compositions should be classified in the relevant subgroups, C23C 4/06 - C23C 4/11.

Metals and metal alloys compositions mixed with inorganic hard particles such as oxides, borides, carbides, nitrides and/or silicides.

MCrAl or MCrAlY alloys, also when further elements are present in said alloys, e.g. Si, ..., and/or hard particles.

Pure metals or metal alloys compositions.

Compositions including mixtures of any two or more of oxides, borides, carbides, nitrides and/or silicides, or pure borides, carbides, nitrides or silicides compositions.

Pure oxides compositions

Coating processes characterised by the method of spraying being not covered by the subgroups.

All specific and well-defined methods and/or apparatuses should be classified in the relevant subgroups, C23C 4/123 - C23C 4/137.

Processes and apparatuses in which the material to be deposited is melted in a furnace, then the molten material is slowly poured through a conical tundish into a small-bore ceramic nozzle. The molten material exits the furnace as a thin free-falling stream and is broken up into droplets by an annular array of gas jets, and these droplets then proceed downwards, accelerated by the gas jets to impact onto a substrate.

Processes and apparatuses where oxygen and fuel is fed into a barrel along with a charge of powder of the material to be deposited. A spark is used to ignite the gas mixture and the resulting detonation heats and accelerates the powder to supersonic velocity down the barrel, to deposit on the substrate.

Schematic diagram of a detonation process:

Processes and apparatuses in which the spray material, in form of a powder or a wire, is fed continually into a fuel gas-oxygen flame where it is typically melted by the heat of combustion. A powder feed carrier gas transports the powder particles into the combustion flame, and the mixed gases transport the material towards the prepared workpiece surface.

Schematic diagram of a wire flame process:

© Sulzer Metco

Schematic diagram of a powder flame process:

© Sulzer Metco

Processes and apparatuses using two metallic wires, usually of the same composition, as the coating feedstock. The two wires are electrically charged with opposing polarity and are fed into the arc gun at matched, controlled speeds. When the wires are brought together at the contact point, the opposing charges on the wires create enough heat to continuously melt the tips of the wires. Compressed air is used to atomize the now molten material and accelerate it onto the workpiece surface to form the coating.

Schematic diagram of a wire arc process:

© Sulzer Metco

Processes and apparatuses where an electric arc is generated between an anode and a cathode. This ionizes the flowing process gases into the plasma state. Powdered feedstock material is injected into the plasma jet, melting the powder particles and propelling them to the surface of the workpiece.

Schematic diagram of a plasma spray process:

© Sulzer Metco

Coating by spraying in vacuum or in an inert gas chamber the coating material in the molten state, for example:

Spraying at below atmospheric pressure

Spraying using inert gas shrouds or in enclosures filled with inert gas

Processes and apparatuses involving pouring molten, i.e. liquid, material onto a substrate to form a coating.

The diffusion of non-metal elements such as carbon, oxygen, nitrogen, but also boron, phosphor, sulfur, selenium or tellurium into a metal or metal alloy surface by contact with either a reactive gas (e.g. oxygen, hydrocarbons, nitrogen), a liquid (e.g. salt melts) or a solid (e.g. powders, pastes).

Coatings obtained by oxidising, carburising, nitriding, carbo-nitriding and/or boronising a metal or metal alloy surface.

Classes are given to well disclosed coatings and/or methods. Classes are further given to related methods, such as pre-treatment(s) of the substrate or after-treatment(s) of the coating.

An operation is considered as pre-treatment or after-treatment when it is specially adapted for, but quite distinct from, the coating process concerned and constitutes an independent operation.

All well-disclosed, non-trivial examples of methods and/or coating are classified.

Precedence rules indicated in the headers of the subgroups are to be strictly followed.

Cleaning or etching treatments

Physical treatments such as roughening, grinding or polishing

Deposition of sublayers, i.e. adhesion layers, masking layers

Masking elements such as casings, shields, fixtures or blocking elements, as well as masking layers or tapes.

Treatments on selected surface areas also not involving masking elements.

Treatment of the metallic surface with ionised gases, leaving reaction products of surface material in the coating, e.g. ionnitriding..

The diffusion of metal elements or silicon into a metal or metal alloy surface by contact with either a reactive gas, a liquid (e.g. salt or metal melts) or a solid (e.g. powders, pastes).

Classes are given to well disclosed coatings and/or methods. Classes are further given to related methods, such as pre-treatment(s) of the substrate or after-treatment(s) of the coating.

An operation is considered as pre-treatment or after-treatment when it is specially adapted for, but quite distinct from, the coating process concerned and constitutes an independent operation.

All well-disclosed, non-trivial examples of methods and/or coatings are classified.

Precedence rules indicated in the headers of the subgroups are to be strictly followed.

Pretreatments of the material to be coated, an operation being considered as pre-treatment when it is specially adapted for, but quite distinct from, the coating process concerned and constitutes an independent operation.

For example:

Masking elements such as casings, shields, fixtures or blocking elements, as well as masking layers or tapes.

Treatments on selected surface areas also not involving masking elements.

The diffusion of at least one non-metal elements other than silicon and at least one metal element or silicon into a metal or metal alloy surface by contact with either a reactive gas, a liquid (e.g. salt or metal melts) or a solid (e.g. powders, pastes).

General considerations.

CPC groups are given only as Invention symbols to well disclosed PVD (physical vapor deposition) coating methods.

CPC groups are further given only as Invention symbols to related methods, such as pre-treatment of the substrate or after-treatment of the coating.

CPC groups are further given only as Invention symbols to apparatus features important to the coating method, such as crucibles for the source material in PVD.

Trivial references to well-known PVD processes are not classified. As an example, "...the SiO₂ layer was deposited by sputtering..." may be mentioned

In this subclass, an operation is considered as pre-treatment or after-treatment when it is specially adapted for, but quite distinct from, the coating process concerned and constitutes an independent operation.

If an operation results in the formation of a permanent sub-layer or upper layer, it is considered as pre-treatment or after- treatment only if it has a direct impact on the layer above or below respectively.

During classification in C23C 14/00 it is common that a document is vague about some of the subject-matter relating to PVD, making the classifier doubt if the document should be classified or not. The classifier should in these cases be guided by his/her own best judgement and the possible importance of the well disclosed subject-matter.

Specific considerations related to specific parts of the classification scheme:

Most of the groups in C23C 14/00 are self-explanatory. Below some explanation of non obvious aspects.

C23C 14/0021-C23C 14/0031: Material in the gas phase is achieved by evaporation, laser ablation etc and reacted with another gas before or during the coating of the substrate. After-treatment with reactive gas in any form is classified in C23C 14/5846-C23C 14/5866.

C23C 14/0036-C23C 14/0084: Material in the gas phase is achieved by sputtering and reacted with another gas before or during the coating of the substrate. After-treatment with reactive gas in any form is classified in C23C 14/5846-C23C 14/5866. Note that the sequential processes in C23C 14/0073 and C23C 14/0078 are not considered as after-treatments.

C23C 14/024-C23C 14/027: The sub-layers are classified only if they have a direct relation to the PVD coating above. Examples are improvement of the adhesion or influence on the structure or properties of the PVD coating above.

C23C 14/04-C23C 14/048: Deliberate action to avoid coating of some areas of the substrate. Merely coating of the front side of a substrate directed towards a source of coating material and not coating the side that the substrate rests on is not classified.

C23C 14/08-C23C 14/088: The alkaline earth, refractory and iron group metals are defined in IPC section C on one of the first pages. Mixed oxides from different groups are classified in C23C 14/08. Mixed oxides from one group is classified in that group. For example Al-Mg-O is classified in C23C 14/081 but Ti-Al-O is classified in C23C 14/08.

C23C 14/10: Note that these materials are usually based on Si-O, but other types of glass should also be classified here.

C23C 14/22: Here, coating processes are classified that does not fit the groups C23C 14/221-C23C 14/48. Examples are processes based on a combinations of CVD and PVD and combinations of different PVD processes.

C23C 14/24-C23C 14/32: Some ionization usually takes place during laser ablation (C23C 14/28) and electron beam induced evaporation (C23C 14/30). However, these documents are not classified in C23C 14/32 unless further ionization of the evaporated material takes place.

C23C 14/34-C23C 14/46. In C23C 14/3407 it is particularly important to classify the method used for building up the target-backing plate unit. Remember that the features of the electrodes as such are classified in H01J 37/34.

Note further that sputtering may be performed with other particles than ions.

A sputtering process is based on the use of the kinetic energy of a particle impacting a target surface releasing target material that is subsequently deposited on a substrate.

C23C 14/56: Normal vacuum pumping is classified here. Deliberate minimization of impurities is classified in C23C 14/564.

C23C 14/58-C23C 14/5893: C23C 14/58 includes after deposition treatment of a coating or film deposited by the techniques of C23C 14/00.

In C23C 14/5826 any treatment with charged particles not being ion beam bombardment is included such as for example plasma treatment.

Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, e.g. chemical vapour deposition (CVD), chemical coating by decomposition of gaseous compounds using electric discharge (plasma coating), using non excited gas phase coating.

General considerations.

CPC groups are given to well disclosed CVD coating methods.

CPC groups are further given to related methods, such as pre-treatment of the substrate or after-treatment of the coating.

CPC groups are further given to apparatus features important to the coating method, such as gas inlets in CVD.

Trivial references to well known CVD processes are not classified. As an example "...the SiO2 layer was deposited by decomposition of TEOS in the presence of oxygen..." may be mentioned.

In this subclass, an operation is considered as pre-treatment or after-treatment when it is specially adapted for, but quite distinct from, the coating process concerned and constitutes an independent operation. If an operation results in the formation of a permanent sub-layer or upper layer, it is considered as pre-treatment or after-treatment only if it has a direct impact on the layer above or below respectively. During classification in C23C 16/00 it is common that a document is vague about some of the subject-matter relating to CVD, making the classifier doubt if the document should be classified or not. The classifier should in these cases be guided by his/her own best judgement and the possible importance of the well disclosed subject-matter.

Specific considerations related to specific parts of the classification scheme.

Most of the groups in C23C 16/00 are self-explanatory. Below some explanation of non obvious aspects.

C23C 16/01: Any method for substrate coating separation is classified here, not only etching.

C23C 16/0272-C23C 16/029: The sub-layers are classified only if they have a direct relation to the CVD coating above. Examples are improvement of the adhesion or influence on the structure or properties of the CVD coating above.

C23C 16/04-C23C 16/047: Deliberately taking action to avoid coating on some areas of the substrate. Merely coating the front side of a substrate directed towards a source of coating material and not coating the side that the substrate rests on is not classified.

C23C 16/27: All processes for deposition of diamond not in the subdivisions C23C 16/271-C23C 16/279 , in particular hybrid and combination processes.

C23C 16/28: For description of the non metal elements see IPC section C one of the first pages. Here, also Ge is considered to be a non-metal as opposed to the definition in the IPC.

C23C 16/40-C23C 16/409: The alkaline earth, refractory and iron group metals are defined in IPC section C on one of the first pages. Mixed oxides from different groups are classified in C23C 16/40. Mixed oxides from one group is classified in that group. For example Al-Mg-O is classified in C23C 16/403 but Ti-Al-O is classified in C23C 16/40.

C23C 16/44: Here, coating processes are classified that does not fit the groups C23C 16/4401-C23C 16/545. Examples are processes based on a combinations of CVD and PVD and combinations of different CVD processes.

C23C 16/452: The most important aspect of this group is the CVD process where radicals but not ions from a plasma takes part in the deposition process.

C23C 16/453: These processes are only classified if a coating is made. Processes for creating "soot" for glass making are not classified here, but in C03C.

C23C 16/45525-C23C 16/45553: Sequentially exposing the substrate to the precursors: Reacting the first precursor with the surface of the substrate and subsequently reacting the first precursor on the surface of the substrate with the second precursor.

C23C 16/45563- C23C 16/4588: These groups relate largely to apparatus features that are important for the deposition process. These features are only classified if documents discloses a relation to a CVD coating method. General documents describing apparatus features are classified in the appropriate places such as H01L and B01J.

C23C 16/46 vs C23C 16/481: Note that C23C 16/481 takes precedence.

C23C 16/50-C23C 16/517: These groups relate to plasma CVD processes where in some cases apparatus features are important. These features are only classified if documents discloses a relation to a plasma CVD coating method. General document describing plasma apparatuses are classified in H01J 37/00.

3 subgroups are present:

-C23C 18/02- C23C 18/14: thermal decomposition through heating or irradiation

-C23C 18/16-C23C 18/52: electroless deposition through use of a chemical reducing agent

-C23C 18/54: electroless deposition through substitution with a more electropositive metal than the one being substituted

These sub-groups and their corresponding sub-divisions are generally self-explanatory but more details is given for the following classes:

Processes, apparatus compositions or compounds for chemical coating by thermal decomposition.

Processes of chemical coating by thermal decomposition characterised by the deposition of material other than inorganic material and involving particles

Apparatus for deposition of particles in general

Process of chemical coating by thermal decomposition characterised by the deposition of metallic material including particles.

Processes of chemical coating by thermal decomposition characterised by deposition of inorganic material other than metallic material, including or not particles are classified in C23C 18/12 subgroups.

Coating for which a pattern area is present, e.g. using masks.

Coatings on selected areas without shielding layer present

Coating for the deposition of metallic material per se and coating for the deposition of aluminium per se through thermal decomposition.

processes and product thereof whereby an inorganic material is deposited through thermal decomposition of its reactant/precursor

apparatus for said process and manufacture of product

4 parts with subdivision are present within this group covering:

C23C 18/1204-C23C 18/122: the composition of the product deposited.

C23C 18/1225: the production of multilayers.

C23C 18/1229-C23C 18/1245: the composition of the substrate onto which the inorganic coating is deposited.

C23C 18/125-C23C 18/1295: the features of the process.

All 4 subdivision have equal weight: classification occurs in any or all of the 4 when features present in claims.

Processes, compositions for chemical coating by thermal decomposition characterised by the deposition of metal oxides other than zeolites or glasses.

Process for deposition of metallic or inorganic material through decomposition by irradiation.

Classification is also given to the material being deposited when known: C23C 18/08, C23C 18/12.

- Process or apparatus for chemical coating by reduction or substitution, for example:

Coatings whereby the electroless coating is patterned.

Electroless deposition on selected surface areas by the use of mask is classified in C23C 18/1605.

Process whereby the electroless coating bath is purified or regenerated.

Pretreatment not specific to a particular substrate as well as pretreatment of metallic substrate to be coated.

The steps of sensitising and activating are either used in a 2 step process or a 1 step process in the patent literature.

The term "sensitising" and "activating" are sometimes used interchangeably in the patent litterature.

Coating with metals through electroless plating process.

Plating of metal surface (e.g. Ni, Cu) with a more electropositive metal (e.g. noble metal).

The groups C23C 20/00-C23C 20/08 are not used. The subject matter is covered by the C23C 18/00 subgroups.

Methods, compositions and apparatus for chemical surface treatment of metallic material by reaction of the metallic surface with a reactive liquid to form conversion or passivation coatings thereon.

This group covers also suspensions containing reactive liquids and non-reactive solid particles.

Apparatus for treating metallic material to form conversion coatings thereon (C23C 22/00).

General methods or special ones for forming conversion coatings on metallic materials that do not have an appropriate subgroup (C23C 22/00).

Conversion coatings (C23C 22/00 - C23C 22/47).

C23C 22/02 . using non-aqueous solutions

C23C 22/05 . using aqueous solutions

C23C 22/70 . using melts

Passivation, oxidation coatings (C23C 22/48 - C23C 22/58).

Conversion coatings characterized by the process (C23C 22/73).

Pretreatment of the material to be coated (C23C 22/78).

After-treatment (C23C 22/82).

Regeneration of the coating bath (C23C 22/86).

Articles characterised by special methods of manufacture are not to be classified in this group but in the appropriate places for such articles, e.g. in F16C for shafts, bearings or parts thereof.

Protective layers or coatings for specific articles are not to be classified in this group but in the appropriate places, e.g. F01D, F28F, A61L, B22C.

In this group it is MANDATORY to classify ALL EXAMPLES of Compositions or Methods.

Other well-disclosed and non-trivial aspects are also classified.

Rejuvenating of the bath is classified in the appropriate place for the specific bath composition.

C23C 22/24 - C23C 22/33, C23C 22/04, C23C 22/37, C23C 22/38, C23C 22/43, C23C 22/67 - treatment with acidic aqueous solutions containing hexavalent chromium compounds - an old technology being phased out due to the carcinogenic effects of hexavalent chromium compounds (see, Restriction of Hazardous Substances (RoHS) - European Union Directive 2002/95/EC).

Classification of additional information

In many cases the classification of additional information is very useful for retrieving the document, and therefore very desirable, although not compulsory. Well-known (trivial) aspects or features are not classified.

For example:

If a document discloses a "conversion process and composition for treatment of aluminium" (C23C 22/56), which in the description is also described as being suitable "for treating magnesium", and if this additional information is per se new /inventive ("non-trivial"), it is classified, namely C23C 22/57 as well.

In some cases the additional information is broadly defined as any secondary information useful for search that is not relevant per se, but that could be interesting for search when considered together with the important (invention-like) information, then it is classified with (Indexing Code), e.g. C23C 2222/10 for searching conversion coatings based on Cr(III) with no Cr(VI), C23C 2222/20 for searching conversion coatings containing or corrosion inhibiting compositions based on silanes or hydrolysis or condensation products thereof.

It is mandatory to classify additional information concerning conversion coating compositions based on Cr(III) in C23C 2222/10. It is mandatory to classify additional information concerning conversion coating compositions based on silanes or hydrolysis or condensation products in C23C 2222/20.

Subgroups and head group

In the head group C23C 22/00, the specific technical information is relevant to the apparatus for treating metallic material to form conversion coatings thereon; and the general methods or special ones for forming conversion coatings on metallic materials that do not have an appropriate subgroup.

In subgroups C23C 22/02 - C23C 22/86, in the absence of an indication to the contrary, classification is made in the last appropriate place.

In the subgroup C23C 22/17 the specific technical information is relevant to the chemical treatment of metallic material with acidic aqueous phosphating solutions which, besides zinc ions, oxidants (nitrite, nitrate, chlorate), contains organic acids, or hydroxylamines, or nitrocompounds, such as nitrobenzene sulfonate.

In the subgroup C23C 22/73 the specific technical information is relevant to the process, e.g. two consecutive treatments or the way how the coating is applied to metallic surfaces.

In the subgroup C23C 22/74 the specific technical information is relevant to the process of conversion coatings formed by chemical reactions of concentrated reactive solutions followed by a thermal treatment (curing step) at temperatures more than 100 - 120 °C.

In the subgroup C23C 22/84 the specific technical information is relevant to the after-treatment (post-treatment) of conversion or passivation coatings by dyeing (coloration). If the conversion or passivation coating is coloured, no classification in C23C 22/84.

Coating methods where the material to be coated is applied in powder form on the surface of the substrate to be coated, e.g. cold spray methods.

Also methods where the coating material is applied in form of a slurry as long as said methods result in obtaining a coating, and not in a modification of the surface of the substrate or in a diffusion into the substrate.

Cold spray methods, i.e. spraying methods in which the sprayed particles are not significantly melted before reaching the substrate.

Any method of coating a metallic surface and/or of coating a substrate with a metallic material which is not already described in any of groups C23C 2/00 - C23C 24/00

Any method of coating a metallic surface with a molten material or molten metallic material to a substrate which is not already described in any of groups C23C 2/00 - C23C 24/00, e.g. brazing, arc welding, laser welding, friction welding, laser alloying

Multi-layered coatings, where the different layers composing the coating have been deposited by at least two different methods as disclosed in group C23C 2/00 - C23C 26/00 or by a combination of one method from C23C and one method from C25D.

Articles characterised by special methods of manufacture are not to be classified in this group but in the appropriate places for such articles, e.g. optical coatings of optical elements G02B 1/10, magnetic record carriers G11B 5/00, resistors H01C 7/00, capacitors H01G 4/00, semiconductor and/or solid-state devices H01L, batteries and/or fuel cells H01M, semiconductor lasers H01S 5/00 and so on.

If a multilayered product classified in B32B is obtained by at least two different methods as disclosed in groups C23C 2/00 - C23C 26/00 or by a combination of methods provided for in subclasses C23C and C25, then the combination of methods should be classified in C23C 28/00 subgroups.

Coatings obtained by any of the methods of group C23C 2/00 - C23C 26/00 but characterized either by the peculiarity of their compositions or of their structures, e.g. columnar thermal barrier coatings, metal matrix composite coatings, two/multi-phase metallic coatings, quasicrystalline coatings, etc.

Essentially coated cutting tools where the coating has been obtained by any of the methods of group C23C 2/00 - C23C 26/00 .

Cutting tools of which the bits, tips or cutting inserts are of a special material are per se classified in B23B 27/14 and not systematically cross-classified in C23C 30/005 when said special material includes a coating.

Cutting tools coated with multi-layered coatings should also be classified in C23C 28/00, when said multi-layered coatings are of a particular interest.