|  | C |
SECTION C — CHEMISTRY; METALLURGY

|  | C |
Note(s) In section C, the definitions of groups of chemical elements are as follows: 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 The following notes are meant to assist in the use of this part of the classification scheme. They must not be read as modifying in any way the elaborations. Section C covers: pure chemistry, which covers inorganic compounds, organic compounds, macromolecular compounds, and their methods of preparation; applied chemistry, which covers compositions containing the above compounds, such as: glass, ceramics, fertilisers, plastics compositions, paints, products of the petroleum industry. It also covers certain compositions on account of their having particular properties rendering them suitable for certain purposes, as in the case of explosives, dyestuffs, adhesives, lubricants, and detergents; certain marginal industries, such as the manufacture of coke and of solid or gaseous fuels, the production and refining of oils, fats and waxes, the fermentation industry (e.g., brewing and wine-making), the sugar industry; certain operations or treatments, which are either purely mechanical, e.g., the mechanical treatment of leather and skins, or partly mechanical, e.g., the treatment of water or the prevention of corrosion in general; metallurgy, ferrous or non-ferrous alloys. In the case of operations, treatments, products or articles having both a chemical and a non-chemical part or aspect, the general rule is that the chemical part or aspect is covered by section C. In some of these cases, the chemical part or aspect brings with it a non-chemical one, even though purely mechanical, because this latter aspect either is essential to the operation or treatment or constitutes an important element thereof. It has seemed, in fact, more logical not to dissociate the different parts or aspects of a coherent whole. This is the case for applied chemistry and for the industries, operations and treatments mentioned in Notes (1)(c), (d) and (e). For example, furnaces peculiar to the manufacture of glass are covered by class Fulltext... Hierarchy... Expanded...C03 and not by class Fulltext... Hierarchy... Expanded...F27. There are, however, some exceptions in which the mechanical (or non-chemical) aspect carries with it the chemical aspect, for example: Certain extractive processes, in subclass Fulltext... Hierarchy... Expanded...A61K; The chemical purification of air, in subclass Fulltext... Hierarchy... Expanded...A61L; Chemical methods of fire-fighting, in subclass Fulltext... Hierarchy... Expanded...A62D; Chemical processes and apparatus, in class Fulltext... Hierarchy... Expanded...B01; Impregnation of wood, in subclass Fulltext... Hierarchy... Expanded...B27K; Chemical methods of analysis or testing, in subclass Fulltext... Hierarchy... Expanded...G01N; Photographic materials and processes, in class Fulltext... Hierarchy... Expanded...G03, and, generally, the chemical treatment of textiles and the production of cellulose or paper, in section D. In still other cases, the pure chemical aspect is covered by section C and the applied chemical aspect by another section, such as A, B or F, e.g., the use of a substance or composition for: treatment of plants or animals, covered by subclass Fulltext... Hierarchy... Expanded...A01N; foodstuffs, covered by class Fulltext... Hierarchy... Expanded...A23; ammunition or explosives, covered by class Fulltext... Hierarchy... Expanded...F42. When the chemical and mechanical aspects are so closely interlocked that a neat and simple division is not possible, or when certain mechanical processes follow as a natural or logical continuation of a chemical treatment, section C may cover, in addition to the chemical aspect, a part only of the mechanical aspect, e.g., after-treatment of artificial stone, covered by class Fulltext... Hierarchy... Expanded...C04. In this latter case, a note or a reference is usually given to make the position clear, even if sometimes the division is rather arbitrary.

METALLURGY

|  | C21 |
METALLURGY OF IRON

|  | C21D |
MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING, OR OTHER TREATMENTS (cementation by diffusion processes Fulltext... Hierarchy... Expanded...C23C; surface treatment of metallic material involving at least one process provided for in class Fulltext... Hierarchy... Expanded...C23 and at least one process covered by this subclass Fulltext... Hierarchy... Expanded...C23F 17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials Fulltext... Hierarchy... Expanded...C30B)

|  | C21D |
Note(s) In this subclass, it is desirable to add the indexing codes of subclass Fulltext... Hierarchy... Expanded...C22K, relating to changing the physical characteristics of alloys. The indexing codes should be unlinked. [6]

|  | C21D |
Subclass index
HEAT TREATMENT |
General methods or devices | 1/00, 11/00
of cast-iron, of iron alloys | 5/00, 6/00
adapted for particular articles | 9/00
MECHANICAL TREATMENT | 7/00
COMBINED MECHANICAL AND THERMAL TREATMENTS | 8/00
OTHER TREATMENTS | 10/00
DIFFUSION PROCESSES FOR EXTRACTION OF NON-METALS | 3/00

|  | C21D 1/00 |
General methods or devices for heat treatments, e.g. annealing, hardening, quenching, tempering (furnaces in general Fulltext... Hierarchy... Expanded...F27; electric heating Fulltext... Hierarchy... Expanded...H05B)

|  | C21D 1/02 |
· | Hardening articles or materials formed by forging or rolling, with no further heating beyond that required for the formation

|  | C21D 1/04 |
· | with simultaneous application of supersonic waves, magnetic or electric fields

|  | C21D 1/06 |
· | Surface hardening

|  | C21D 1/08 |
· · | with flames

|  | C21D 1/09 |
· · | by direct application of electrical or wave energy; by particle radiation [3]

|  | C21D 1/10 |
· · · | by electric induction [3]

|  | C21D 1/18 |
· | Hardening (Fulltext... Hierarchy... Expanded...C21D 1/02 takes precedence); Quenching with or without subsequent tempering (quenching devices Fulltext... Hierarchy... Expanded...C21D 1/62) [3]

|  | C21D 1/19 |
· · | by interrupted quenching [3]

|  | C21D 1/20 |
· · · | Isothermal quenching, e.g. bainitic hardening [3]

|  | C21D 1/22 |
· · · | Martempering [3]

|  | C21D 1/25 |
· · | Hardening, combined with annealing between 300°C and 600°C, i.e. heat refining ("Vergüten") [3]

|  | C21D 1/26 |
· | Methods of annealing

|  | C21D 1/28 |
· · | Normalising

|  | C21D 1/30 |
· · | Stress-relieving

|  | C21D 1/32 |
· · | Soft annealing, e.g. spheroidising

|  | C21D 1/34 |
· | Methods of heating (Fulltext... Hierarchy... Expanded...C21D 1/06 takes precedence)

|  | C21D 1/38 |
· · | Heating by cathodic discharges

|  | C21D 1/40 |
· · | Direct resistance heating

|  | C21D 1/42 |
· · | Induction heating

|  | C21D 1/44 |
· · | in heat-treatment baths

|  | C21D 1/46 |
· · · | Salt baths

|  | C21D 1/48 |
· · · | Metal baths

|  | C21D 1/50 |
· · · | Oil baths

|  | C21D 1/52 |
· · | with flames

|  | C21D 1/53 |
· · | Heating in fluidised beds [3]

|  | C21D 1/54 |
· | Determining when the hardening temperature has been reached by measurement of magnetic or electrical properties

|  | C21D 1/55 |
· | Hardenability tests, e.g. end-quench tests (investigating or analysing materials by determining their chemical or physical properties, in general Fulltext... Hierarchy... Expanded...G01N) [3]

|  | C21D 1/56 |
· | characterised by the quenching agents

|  | C21D 1/58 |
· · | Oils

|  | C21D 1/60 |
· · | Aqueous agents

|  | C21D 1/607 |
· · | Molten salts [3]

|  | C21D 1/613 |
· · | Gases; Liquefied or solidified normally gaseous material [3]

|  | C21D 1/62 |
· | Quenching devices

|  | C21D 1/63 |
· · | for bath quenching [3]

|  | C21D 1/64 |
· · · | with circulating liquids (in general Fulltext... Hierarchy... Expanded...F28D) [3]

|  | C21D 1/667 |
· · | for spray quenching [3]

|  | C21D 1/673 |
· · | for die quenching [3]

|  | C21D 1/68 |
· | Temporary coatings or embedding materials applied before or during heat treatment

|  | C21D 1/70 |
· · | while heating or quenching

|  | C21D 1/72 |
· · | during chemical change of surfaces

|  | C21D 1/74 |
· | Methods of treatment in inert gas, controlled atmosphere, vacuum, or pulverulent material (production of gases Fulltext... Hierarchy... Expanded...C01, Fulltext... Hierarchy... Expanded...C10)

|  | C21D 1/76 |
· · | Adjusting the composition of the atmosphere

|  | C21D 1/767 |
· · | with forced gas circulation; Reheating thereof [3]

|  | C21D 1/773 |
· · | under reduced pressure or vacuum [3]

|  | C21D 1/78 |
· | Combined heat-treatments not provided for above

|  | C21D 1/82 |
· | Descaling by thermal stresses (mechanically Fulltext... Hierarchy... Expanded...B21, Fulltext... Hierarchy... Expanded...B23, chemically Fulltext... Hierarchy... Expanded...C23, electrolytically Fulltext... Hierarchy... Expanded...C25F)

|  | C21D 1/84 |
· | Controlled slow cooling (cooling-beds for metal rolling Fulltext... Hierarchy... Expanded...B21B 43/00) [3]

|  | C21D 3/00 |
Diffusion processes for extraction of non-metals; Furnaces therefor (local protective coatings Fulltext... Hierarchy... Expanded...C21D 1/72; furnaces in general Fulltext... Hierarchy... Expanded...F27)

|  | C21D 3/02 |
· | Extraction of non-metals

|  | C21D 3/04 |
· · | Decarburising

|  | C21D 3/06 |
· · | Extraction of hydrogen

|  | C21D 3/08 |
· · | Extraction of nitrogen

|  | C21D 3/10 |
· | Furnaces therefor

|  | C21D 5/00 |
Heat treatments of cast-iron

|  | C21D 5/02 |
· | improving the malleability of grey cast-iron

|  | C21D 5/04 |
· | of white cast-iron

|  | C21D 5/06 |
· · | Malleabilising

|  | C21D 5/08 |
· · · | with oxidation of carbon

|  | C21D 5/10 |
· · · · | in gaseous agents

|  | C21D 5/12 |
· · · · | in solid agents

|  | C21D 5/14 |
· · · | Graphitising

|  | C21D 5/16 |
· · · · | Packing agents

|  | C21D 6/00 |
Heat treatment of ferrous alloys [2]

|  | C21D 6/02 |
· | Hardening by precipitation [2]

|  | C21D 6/04 |
· | Hardening by cooling below 0 C [2]

|  | C21D 7/00 |
Modifying the physical properties of iron or steel by deformation (apparatus for mechanical working of metal Fulltext... Hierarchy... Expanded...B21, Fulltext... Hierarchy... Expanded...B23, Fulltext... Hierarchy... Expanded...B24, e.g. shot-peening Fulltext... Hierarchy... Expanded...B24C)

|  | C21D 7/02 |
· | by cold working

|  | C21D 7/04 |
· · | of the surface

|  | C21D 7/06 |
· · · | by shot-peening or the like

|  | C21D 7/08 |
· · · | by burnishing or the like

|  | C21D 7/10 |
· · | of the whole cross-section, e.g. of concrete reinforcing bars

|  | C21D 7/12 |
· · · | by expanding tubular bodies

|  | C21D 7/13 |
· | by hot working

|  | C21D 8/00 |
Modifying the physical properties by deformation combined with, or followed by, heat treatment (hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation Fulltext... Hierarchy... Expanded...C21D 1/02) [3]

|  | C21D 8/02 |
· | during manufacturing of plates or strips (Fulltext... Hierarchy... Expanded...C21D 8/12 takes precedence) [3]

|  | C21D 8/04 |
· · | to produce plates or strips for deep-drawing [3]

|  | C21D 8/06 |
· | during manufacturing of rods or wires [3]

|  | C21D 8/08 |
· · | for concrete reinforcement [3]

|  | C21D 8/10 |
· | during manufacturing of tubular bodies [3]

|  | C21D 8/12 |
· | during manufacturing of articles with special electromagnetic properties [3]

|  | C21D 9/00 |
Heat treatment, e.g. annealing, hardening, quenching, tempering, adapted for particular articles; Furnaces therefor (furnaces in general Fulltext... Hierarchy... Expanded...F27)

|  | C21D 9/02 |
· | for springs

|  | C21D 9/04 |
· | for rails (apparatus for heat treatment of railway rails on the spot Fulltext... Hierarchy... Expanded...E01B 31/18)

|  | C21D 9/06 |
· · | with diminished tendency to become wavy

|  | C21D 9/08 |
· | for tubular bodies or pipes

|  | C21D 9/10 |
· · | shotgun barrels

|  | C21D 9/12 |
· · | barrels for ordnance

|  | C21D 9/14 |
· · | wear- or pressure-resistant pipes

|  | C21D 9/16 |
· | for explosive shells

|  | C21D 9/18 |
· | for knives, scythes, scissors, or like hand cutting tools

|  | C21D 9/20 |
· | for blades for skates

|  | C21D 9/22 |
· | for drills; for milling cutters; for machine cutting tools

|  | C21D 9/24 |
· | for saw blades

|  | C21D 9/26 |
· | for needles; for teeth for card-clothing

|  | C21D 9/28 |
· | for plain shafts

|  | C21D 9/30 |
· | for crankshafts; for camshafts

|  | C21D 9/32 |
· | for gear wheels, worm wheels, or the like

|  | C21D 9/34 |
· | for tyres; for rims

|  | C21D 9/36 |
· | for balls; for rollers

|  | C21D 9/38 |
· | for roll bodies

|  | C21D 9/40 |
· | for rings; for bearing races

|  | C21D 9/42 |
· | for armour plate

|  | C21D 9/44 |
· | for equipment for lining mine shafts, e.g. segments, rings, props

|  | C21D 9/46 |
· | for sheet metals

|  | C21D 9/48 |
· · | deep-drawing sheets

|  | C21D 9/50 |
· | for welded joints

|  | C21D 9/52 |
· | for wires; for strips

|  | C21D 9/54 |
· · | Furnaces for treating strips or wire

|  | C21D 9/56 |
· · · | Continuous furnaces for strip or wire

|  | C21D 9/567 |
· · · · | with heating in fluidised beds [3]

|  | C21D 9/573 |
· · · · | with cooling [3]

|  | C21D 9/58 |
· · · · | with heating by baths

|  | C21D 9/60 |
· · · · | with induction heating

|  | C21D 9/62 |
· · · · | with direct resistance heating

|  | C21D 9/63 |
· · · · | the strip being supported by a cushion of gas [3]

|  | C21D 9/64 |
· · · | Patenting furnaces

|  | C21D 9/66 |
· · · | Tower-type furnaces

|  | C21D 9/663 |
· · · | Bell-type furnaces [3]

|  | C21D 9/665 |
· · · · | inverted or side-facing [3]

|  | C21D 9/667 |
· · · · | Multi-station furnaces [3]

|  | C21D 9/67 |
· · · · · | adapted for treating the charge in vacuum or special atmosphere [3]

|  | C21D 9/673 |
· · · · | Details, accessories, or equipment peculiar to bell-type furnaces [3]

|  | C21D 9/675 |
· · · · | Arrangements of charging or discharging devices [3]

|  | C21D 9/677 |
· · · · | Arrangements of heating devices [3]

|  | C21D 9/68 |
· · · | Furnace coilers; Hot coilers (cold coilers Fulltext... Hierarchy... Expanded...B21C)

|  | C21D 9/70 |
· | Furnaces for ingots, i.e. soaking pits

|  | C21D 10/00 |
Modifying the physical properties by methods other than heat treatment or deformation [3]

|  | C21D 11/00 |
Process control or regulation for heat treatments (controlling or regulating in general Fulltext... Hierarchy... Expanded...G05) [2]