|  | C |
SECTION C — CHEMISTRY AND METALLURGY

|  | C |
Note(s) Definitions for Section C: Alkali metals: Li, Na, K, Rb, Cs, Fr Alkaline earth metals: Ca, Sr, Ba, Ra Lanthanides: elements with atomic numbers 57 to 71 inclusive Rare earths: Sc, Y, Lanthanides Actinides: elements with atomic numbers 89 to 103 inclusive Refractory metals: Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W Halogens: F, Cl, Br, I, At Noble gases: He, Ne, Ar, Kr, Xe, Rn Platinum group: Os, Ir, Pt, Ru, Rh, Pd Noble metals: Ag, Au, Platinum group Light metals: alkali metals, alkaline earth metals, Be, Al, Mg Heavy metals: metals other than light metals Iron group: Fe, Co, Ni Non-metals: H, B, C, Si, N, P, O, S, Se, Te, noble gases, halogens Metals: elements other than non-metals Transition elements: elements with atomic numbers 21 to 30 inclusive, 39 to 48 inclusive, 57 to 80 inclusive, 89 upwards

METALLURGY

|  | C23 |
WORKING OR TREATMENT OF METALS, OTHER THAN BY MECHANICAL MEANS; COVERING MATERIALS WITH METALS (decorating textiles by metallising Fulltext... Hierarchy... Expanded...D06Q 1/04); INHIBITING CORROSION OR INCRUSTATION IN GENERAL (treating metal surfaces or coating of metals by electrolysis or electrophoresis Fulltext... Hierarchy... Expanded...C25D, Fulltext... Hierarchy... Expanded...C25F) [2]

|  | C23F |
CHEMICAL SURFACE TREATMENT OF METALS NOT COVERED BY SUB-CLASSES Fulltext... Hierarchy... Expanded...C23D, Fulltext... Hierarchy... Expanded...C25D; INHIBITING CORROSION OR INCRUSTATION IN GENERAL

|  | C23F |
Note(s) This sub-class is the general place for inhibiting corrosion or incrustation in general, whether of or on metallic or non-metallic surfaces. It does not include, however: protective layers or coating compositions or methods of applying them; these are classified in the relevant class, e.g. Fulltext... Hierarchy... Expanded...B05, Fulltext... Hierarchy... Expanded...B44, Fulltext... Hierarchy... Expanded...C09D. mechanical devices or constructional features of particular articles; these are classified in the relevant class, e.g. pipes, pipe fittings Fulltext... Hierarchy... Expanded...F16L. articles characterised by being made of materials selected for their properties of resistance to corrosion or incrustation; these are classified in the relevant class, e.g. turbine blades Fulltext... Hierarchy... Expanded...F01D 5/28.

|  | C23F 1/00 |
Etching metals by chemical means (manufacture of printing surfaces Fulltext... Hierarchy... Expanded...B41C; etching compositions Fulltext... Hierarchy... Expanded...C09K 13/00; electrolytic etching Fulltext... Hierarchy... Expanded...C25F 3/00) [2]

|  | C23F 1/02 |
· | Local etching

|  | C23F 1/04 |
· · | Chemical milling

|  | C23F 1/06 |
· | Sharpening files

|  | C23F 1/08 |
· | Apparatus, e.g. for photomechanical printing surfaces (photomechanical reproduction Fulltext... Hierarchy... Expanded...G03F)

|  | C23F 3/00 |
Brightening metals by chemical means (brightening compositions Fulltext... Hierarchy... Expanded...C09K 13/00) [2]

|  | C23F 3/02 |
· | light metals

|  | C23F 3/04 |
· | heavy metals

|  | C23F 5/00 |
Forming coloured layers on metal surfaces (Fulltext... Hierarchy... Expanded...C23F 7/00 takes precedence)

|  | C23F 5/02 |
· | with inorganic colouring matters

|  | C23F 5/04 |
· | with organic colouring matters

|  | C23F 7/00 |
Forming non-metallic layers on metals by surface reactions (diffusion processes Fulltext... Hierarchy... Expanded...C23C)

|  | C23F 7/02 |
· | Forming oxide layers

|  | C23F 7/04 |
· · | on iron or steel

|  | C23F 7/06 |
· · | on light metals

|  | C23F 7/08 |
· | Forming phosphate layers

|  | C23F 7/10 |
· · | on iron or steel

|  | C23F 7/12 |
· · | on copper, brass, zinc, or tin

|  | C23F 7/14 |
· · | on light metals

|  | C23F 7/16 |
· · · | on magnesium

|  | C23F 7/18 |
· | Forming oxalate layers

|  | C23F 7/20 |
· · | on iron or steel

|  | C23F 7/22 |
· · | on light metals

|  | C23F 7/24 |
· | Forming sulphide layers

|  | C23F 7/26 |
· | Forming chromate layers

|  | C23F 9/00 |
Passivating metals

|  | C23F 9/02 |
· | iron or steel

|  | C23F 11/00 |
Inhibiting corrosion by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent (adding inhibitors to mineral oil, fuels, or lubricants Fulltext... Hierarchy... Expanded...C10; adding inhibitors to pickling solutions Fulltext... Hierarchy... Expanded...C23G)

|  | C23F 11/02 |
· | in air or gases by adding vapour phase inhibitors

|  | C23F 11/04 |
· | in markedly acid liquids

|  | C23F 11/06 |
· | in markedly alkaline liquids

|  | C23F 11/08 |
· | in other liquids

|  | C23F 11/10 |
· · | using organic inhibitors

|  | C23F 11/10 |
Note(s) A compound is classified in the last appropriate place.

|  | C23F 11/12 |
· · · | oxygen-containing compounds

|  | C23F 11/14 |
· · · | nitrogen-containing compounds

|  | C23F 11/16 |
· · · | compounds containing sulphur or phosphorus

|  | C23F 11/18 |
· · | using inorganic inhibitors

|  | C23F 13/00 |
Inhibiting corrosion of metals by anodic or cathodic protection

|  | C23F 14/00 |
Inhibiting incrustation in apparatus for heating liquids for physical or chemical purposes (adding scale preventives or removers to water Fulltext... Hierarchy... Expanded...C02F 5/00) [2]

|  | C23F 14/02 |
· | by chemical means

|  | C23F 15/00 |
Other methods of preventing corrosion or incrustation

|  | C23F 17/00 |
Multi-step processes for chemical or physical, i.e. non-mechanical, surface treatment of or with metals, in which at least one step is a process covered in Fulltext... Hierarchy... Expanded...C21D, Fulltext... Hierarchy... Expanded...C22F or Fulltext... Hierarchy... Expanded...C23