Premium
Investigation of Gases Evolved During Firing of Porcelain Enamels
Author(s) -
MOORE DWIGHT G.,
MASON MARY A.
Publication year - 1953
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1953.tb12876.x
Subject(s) - bubble , hydrogen , carbon monoxide , coating , materials science , enamel paint , carbon dioxide , metallurgy , carbon fibers , composite material , chemistry , composite number , biochemistry , organic chemistry , parallel computing , computer science , catalysis
An investigation was made of the gases evolved during the firing of porcelain enamels. The investigation included (1) examination of gas evolution with a microscope while specimens were being fired, (2) examination of fired specimens for changes in bubble structure with firing time, (3) examination of the changes in the normal gas evolution when water‐free enamels were used, (4) analysis with the mass spectrometer of the gases trapped in the bubble structure after varying firing times, (5) determination of the source of the carbon gases in the bubble structure using radioactive C 14 as a tracer, and (6) determination of the effect of various pretreatments of the clay used for suspending the coating slip on the resulting bubble structure of the fired specimens. The results showed that the principal gases evolved during the firing were carbon monoxide, carbon dioxide, and hydrogen. The blistering that is often observed in the early stage of firing when porcelain enamels are applied to low‐carbon steel was found to be caused by evolution of the carbon gases formed by the oxidation of the carbon in the steel. Evidence was obtained that the hydrogen formed from the reaction between the dissolved water in the coating and the hot‐iron base slowly diffuses into the coating as the firing continues. Some of the hydrogen also diffuses into the metal. On fast cooling this hydrogen is expelled, causing bubbles to form in the coating at the interface. It was found that a considerable portion of the bubble structure in an enamel fired for a normal time is due to some impurity in the clay mill addition. The impurity is probably organic matter adsorbed on the clay particles.