C
SECTION C — CHEMISTRY; METALLURGY
 C

Note(s)

  1. 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

  2. Section C covers :
    1. pure chemistry, which covers inorganic compounds, organic compounds, macromolecular compounds, and their methods of preparation;
    2. 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;
    3. 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;
    4. 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;
    5. metallurgy, ferrous or non-ferrous alloys.
  3. In all sections of the IPC, in the absence of an indication to the contrary, the Periodic System of chemical elements referred to is the one with 8 groups as represented in the table below. For example, group C07F 3/00 "Compounds containing elements of the 2nd Group of the Periodic System" refers to the elements of columns IIa and IIb. [2009.01]

    1. 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.
    2. 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 C03 and not by class F27.
    3. There are, however, some exceptions in which the mechanical (or non-chemical) aspect carries with it the chemical aspect, for example:
    4. 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:
    5. 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 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 C23C; surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F 17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B)
 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
P:70 C21D 1/00
General methods or devices for heat treatment, e.g. annealing, hardening, quenching, tempering (furnaces in general F27; electric heating 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 (C21D 1/02 takes precedence); Quenching with or without subsequent tempering (quenching devices 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 (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 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 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 C01, 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 B21, B23; chemically C23; electrolytically C25F)
 C21D 1/84
·  Controlled slow cooling (cooling-beds for metal rolling B21B 43/00)  [3]
P:10 C21D 3/00
Diffusion processes for extraction of non-metals; Furnaces therefor (local protective coatings C21D 1/72; furnaces in general 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
P:50 C21D 5/00
Heat treatment 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
P:60 C21D 6/00
Heat treatment of ferrous alloys  [2]
 C21D 6/00

Note(s)

  1. When classifying in group C21D 6/00, any aspect of the method for the heat treatment of ferrous alloys which is considered to represent information of interest for search may also be classified in groups C21D 1/02-C21D 1/84. This can, for example, be the case when it is considered of interest to enable searching of heat treatment methods of ferrous alloys using a combination of classification symbols. Such non-obligatory classification should be given as "additional information". [8]
  2. When classifying in group C21D 6/00, any alloying constituent which is considered to represent information of interest for search may also be classified in groups C22C 38/02-C22C 38/60. This can, for example, be the case when it is considered of interest to enable searching of heat treatment of specific ferrous alloys using a combination of classification symbols. Such non-obligatory classification should be given as "additional information". [8]
 C21D 6/02
·  Hardening by precipitation  [2]
 C21D 6/04
·  Hardening by cooling below 0° C  [2]
P:30 C21D 7/00
Modifying the physical properties of iron or steel by deformation (apparatus for mechanical working of metal B21, B23, B24)
 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
P:20 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 C21D 1/02)  [3]
 C21D 8/02
·  during manufacturing of plates or strips (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]
P:40 C21D 9/00
Heat treatment, e.g. annealing, hardening, quenching, tempering, adapted for particular articles; Furnaces therefor (furnaces in general F27)
 C21D 9/02
·  for springs
 C21D 9/04
·  for rails (apparatus for heat treatment of railway rails on the spot 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 B21C)
 C21D 9/70
·  Furnaces for ingots, i.e. soaking pits
P:80 C21D 10/00
Modifying the physical properties by methods other than heat treatment or deformation  [3]
P:0 C21D 11/00
Process control or regulation for heat treatments (controlling or regulating in general G05)  [2]