摘要:

AbstractThe resistance of representative porcelain enamel surfaces to the chemical attack of different concentrations of various solutions was investigated in considerable detail. Cylindrical cup‐shaped samples were coated with (1) a ground coat, (2) a white fluoride cover enamel, (3) a white antimony cover enamel, (4) a white zirconium cover enamel, (5) an acid‐resistant white cover enamel, (6) a sign blue cover enamel, (7) a blue zirconium enamel, and (8) a chemical acidproof blue cover enamel. The loss in weight of these enamel surfaces, after exposure to chemical attack, was determined at definite time intervals. The solutions studied consisted of different concentrations of the inorganic acids, alkalis, several organic acids, as well as selected salt solutions at both room and boiling temperatures.Numerous curves are presented showing the comparative chemical durability of the various porcelain enamel surfaces in which the cumulative loss in weight is plotted against time. Several photomicrographs show the nature and type of chemical attack on the different surfaces.The porcelain enamel surfaces showed considerable variation in their resistance to the chemical attack of the various solutions. All of the porcelain enamels were, in general, resistant to attack at room temperature by the alkali and salt solutions. The acid‐resistant and acidproof enamels were resistant to the action of both inorganic and organic acids at room and at boiling temperatures; a wide variance, however, was shown in the comparative acid resistance of the non‐acid‐resisting enamel to the attack of either organic acids or inorganic acids at room temperature. AU porcelain enamels showed equally low resistance to boiling alkali solutions, but some of the enamel surfaces were attacked markedly by the boiling salt

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1945.tb14540.x

出版商:Blackwell Publishing Ltd    

年代:1945

数据来源: WILEY

摘要:

AbstractA heavy, disagreeable scumming developed on a surface of stoneware articles. This scum, having the appearance of a wrinkled skin, prevented the body from taking the salt glaze on account of its refractory character. It consisted almost entirely of the mineral anorthite, and its formation is attributed to the aluaite content of the clay.SummaryThe scum coating which appeared on a stoneware body on firing proved to be composed essentially of the mineral anorthite as determined by chemical analysis and microscopic examination.The substance to be blamed for the scum formation seems to be the alunite, which has been found in the clay in exceedingly large quantities. Although the alunite content of the clay remained at 15%, no troubles have been observed from its presence. The explanation for the scum‐formation mechanism is that the potassium sulfate, which remains as the only soluble and readily fusible compound after the decomposition of the alunite, dissolves the calcium sulfate, alumina, and silica and migrates to the surface at temperatures closely approaching that of the clay vitrifying point. The anorthite may easily crystallize out of the melt of the potassium sulfate, which is volatilized and disappears completel

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1945.tb14541.x

出版商:Blackwell Publishing Ltd    

年代:1945

数据来源: WILEY

摘要:

AbstractThe development of a low‐fire mat glaze for studio use is described in which part of the fluxes and silica and alumina are supplied by the use of wood ash. The materials required are simple and readily obtained and the glaze is easy to apply. One firing is eliminated by its application to the green ware, and the firing range is from cones 04 to 02.SummaryIn the glaze described, wood ash supplies a part of the silica and alumina çontent along with certain fluxes of which calcium is the more important.In the alumina‐type mats, wood ash produces a texture similar to that of the stoneware glaze which was the source of inspiration.The glaze can be applied by brushing, pouring, or spraying on the green ware or on bisque‐fire ware; brushing on the unfired ware is preferable. An over‐thick application destroys the beauty of the glaze.The glaze does not crawl and it is self‐healing when drying cracks appear; no cracks, however, have appeared when the glaze has been used on green ware. Handsome colors can be produced with the use of very little colo

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1945.tb14542.x

出版商:Blackwell Publishing Ltd    

年代:1945

数据来源: WILEY