CPC Definition - Subclass C23D

Last Updated Version: 2023.02
ENAMELLING OF, OR APPLYING A VITREOUS LAYER TO, METALS
Definition statement

This place covers:

Processes for enamelling or for applying glass layers on metal.

Enamelling is here only the coating of metals with vitreous powders in dry form, in dispersion or mixed with a polymeric binder (e.g. transfer sheets) that will disappear during burning without leaving byproducts. The heat treatment is here to melt the powder and eventually to burn the carrier, when present.

The coating of metal with glass can be done by the same processes as enamelling, by coating with molten glass.

Relationships with other classification places

Enamel and glass compositions are classified in C03C.

References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Layered products comprising a layer of metal

B32B 15/00

Enamel compositions

C03C 8/00

Glazes on ceramics

C04B 41/00

Organic coatings on metal

C09D, B05D

Ceramic coatings on metal

C23C 4/00, C23C 24/00, C23C 26/00, C23C 28/00

Coating with fused refractory layers

C23C 4/10, C23C 24/10

Special rules of classification

Inorganic coatings on metal that are formed from the decomposition of precursors should be classified in C23C 18/00 and subgroups (for example sol-gels on metal are not classified in C23D).

When the process is only characterized by the composition of one enamel layer, then it should be classified in the composition groups (C03C 8/00 and subgroups).

Some documents disclose "cold enamels", these are considered as paints, and should be classified in relevant classes (C09D, B05D, ...).

Some documents disclose enamel on ceramics, these should be considered as glazes and not enamels, they should be classified in C04B 41/00.

As silicon is not a metal (see CPC section C), no coating on silicon is classified in C23D.

Chemical treatment of the metal surfaces prior to coating
Definition statement

This place covers:

Pre-treatment of metals when they are specific to enamelling.

References
Informative references

Attention is drawn to the following places, which may be of interest for search:

Coating metallic material; Coating material with metallic material

C23C

Non-mechanical removal of metallic material from surfaces; Inhibiting corrosion of metallic material

C23F

Cleaning or de-greasing of metallic objects

C23G

{with refractory materials}
References
Limiting references

This place does not cover:

Coating metals with ceramics

C23C

Special rules of classification

Documents should be classified in C23C 4/10 and C23C 24/10. No new document in this group.

Ovens specially adapted for firing enamels
Relationships with other classification places

Industrial oven should be classified in F27B