THE USE OF NATURAL GAS IN FIRING STRUCTURAL CLAY PRODUCTS1

Some of the advantages of natural-gas firing are enumerated and the thermal value and cost of natural gas are compared with coal. Other points discussed in the paper are: (1) the influence of irregular operation and length of firing schedule on economy, (2) the value of controlled air supply under pressure, and (3) the reported gas consumption for various products in different districts.     

THE DETERMINATION OF ZINC IN REFRACTORY BODIES AND SLAGS1

An earlier published method for the determination of zinc in discarded retorts and other refractory bodies was found to be accurate but too tedious for commercial work. An effort was made to develop a shorter method. It was found that the ordinary ammonia-ammonium chloride separation of iron from zinc is not accurate in the presence of relatively large amounts of alumina. A rapid method involving the separation of zinc from iron and alumina under conditions involved in the analysis of refractory bodies was developed. The method consists in precipitating iron and zinc sulphides from an ammoniacal solution containing the three ions, in which the alumina is held in solution by the presence of citric acid, Methods for the determination of zinc are discussed and reasons given for the adoption of the gravimetric method involving the precipitation of zinc sulphide from a faintly acid solution.     

THE EFFECT OF VARIATION IN FIRING ON THE PHYSICAL PROPERTIES OF VITREOUS CHINA BODIES1

The porosity, transverse strength, compressive strength and impact strength of ten commercial china bodies were determined on sets of specimens fired in three positions in a kiln in each of ten potteries. The results showed that while there was considerable difference in the maximum strength of the bodies, nearly all of them developed high strength when fired most advantageously. The maximum strength existed over a narrower range in heat treatment than that of complete vitrification. Underfiring and overfiring of this type of body caused serious loss in strength. Specimens of eleven bodies fired at cones 6, 8, 10, 12 and 14 in a laboratory kiln showed about the same differences in maximum strength as specimens of the same bodies fired in the pottery kilns. In one body only was as high strength. developed in the small kiln as in the factory. In most instances the highest strength developed was coincident with complete vitrification and in all the bodies it occurred near or prior to cone 12. There was considerable difference in the range in temperature over which the different bodies were vitrified and were of high strength. While two of the bodies were excellent in this respect, the remainder were vitrified and of high strength through only a narrow temperature range.     

METHODS FOR THE DETERMINATION OF THE FIRING RANGE OF VITREOUS ENAMELS USED IN WET-PROCESS ENAMELING1

Several methods for making firing range studies in case of wet-process enamels are described. The methods used in producing enamel deposits of predetermined weights are given. The use of these methods has shown that enamels used in wet-process enameling of metal vary widely in action under various conditions of heat and a general discussion of the subject is included.     

REFRACTORY REQUIREMENTS IN THE GRAY IRON FOUNDRY1

The author calls attention to the lack of information on foundry refractories on the part of both foundrymen and makers of refractory materials. The applications of these materials in foundry practice are enumerated, and the requirements detailed sufficiently to enable the manufacturer to selcct the proper grades of brick and clay for cupola and air furnace operation, as well as for the lining up of ladles.     

THE PHYSICAL STRUCTURE OF REFRACTORY MATERIALS1

The relation of physical structure to the performance characteristics is pointed out. It is shown that chemical composition is of value principally as a means of control of raw materials, the value of the end product being determined largely by the crystallographic relationship existing between grain and bond.     

THE EFFECT OF FURNACE ATMOSPHERE ON THE FIRING OF ENAMEL1

It is shown that in firing ground coat and other one coat enamels, the atmosphere of the furnace plays an important part. Oxygen in the muffle penetrates the enamel during the early stages of the firing forming a film of iron oxide on the surface of the steel. This film, whether applied before enameling or formed incidentally to firing, partially dissolves in the fused enamel giving the intimate bond between metal and enamel. Ground coat enamel fired in an atmosphere of nitrogen was found not to adhere to the steel. Approximate values are given for the proportion of furnace space to enameled surface to insure sufficient oxidation when residual air is depended upon to supply the oxygen.     

THE SERVICE OF REFRACTORY BLOCKS IN A SMALL EXPERIMENTAL GLASS TANK1

Tests to determine the relative resistance of various types of refractories to the action of flowing molten glass were made in a small laboratory glass-melting furnace similar in shape and in operation to commercial scale, continuous glass tanks. The results of tests made in nine runs of the furnace, each run continuing for approximately 30 days, are given. The resistance of the refractories to glass attack apparently does not depend entirely upon chemical composition and porosity of the refractories, but is probably related also to (1) the size of pores, (2) the relative composition of grog and bond, and (3) the degree of adherence between particles in the refractory.     

THE EFFECT OF DE-AIRING ON THE STRENGTH OF STIFF-MUD PRODUCTS IN THE WET STATE1

The strength of one-inch square stiff-mud bars is determined by bending until they break and the angle of bending is determined as a measure of the wet strength.     

PROGRESS IN THE ELIMINATION OF SAGGERS IN THE FIRING OF GLOST AND BISQUE GENERAL WARE AND GLOST WALL TILE1

During the past fourteen years the use of saggers has been largely eliminated in the sanitary ware industry by the use of cars equipped with permanent superstructures of slabs and posts in muffle tunnel kilns. Methods are described by which saggers can be eliminated for firing general ware and wall tiles with correspondinn benefits.     

耐火材料中铝的化学分析方法研究

近年来,耐火材料的理化性质测定方法不断改进,为适应其发展的需要,主要介绍了耐火材料中铝的分析方法以及各种分析方法的特点,讨论了测定铝的影响因素;从而为不同的耐火材料中铝的分析方法的确定以及耐火原料级别和品位的评定提供重要依据.     

THE DIELECTRIC STRENGTH OF PORCELAIN: THE INFLUENCE OF FIRING TEMPERATURE1

This paper completes the work previously reported by Monack and Shardlow² The additional puncture voltages in kilovolts per quarter-inch thickness were cone 13, 60; cone 14, 69.5; cone 15, 67. The puncture voltage increased gradually between cones 9 and 15. Other conditions remaining identical, it was shown that the most uniform body resulted when tired to cone 9.     

THE THERMAL EXPANSION OF SOME REFRACTORY OXIDES1

The thermal expansion of crystals of alpha-alumina, magnesia, chromite, mullite, and zircon and of a mass of fused zirconia has been measured up to 1000°C. The results are exhibited in tables and in graphical form.     

THE EFFECT OF FIRING TEMPERATURE ON THE DIELECTRIC STRENGTH OF PORCELAIN1

An electrical porcelain body (H and G A1 English china clay, 30%; Tennessee ball clay No. 7, 20%; Buckingham feldspar, 30%; Ottawa flint, 20%) was fired to various cone temperatures and the puncture voltages were determined. The mean values in kilovolts per quarter-inch thickness were cone 7, 37; cone 8, 51; cone 9, 60; cone 10, 63; cone 11, 61; cone 12, 64. The probable error of the mean in each case is approximately ± 1 kilovolt per quarter inch. The differences of the means between cones 9 and 12 were shown statistically to be without significance. Other conditions remaining identical, it was shown that the most uniform body resulted when fired to cone 9.     

THE DETERMINATION OF THE BULK AND PORE VOLUMES OF REFRACTORY MATERIALS1

A new sand displacement method for the determination of the bulk volume and bulk specific gravity of refractory or other material is described. A gas porosimeter with a vertical U-tube manometer for the determination of pore volumes of materials is also described together with calculations of the possible errors. The porosities, bulk specific gravities, and calculated true specific gravities of 15 types of refractory bricks obtained by means of these two methods, and the usual water absorption method are tabulated for comparison.     

EXPANSION STRAINS IN THE INITIAL FIRING OF CERAMIC WARE*

The initial firing of some ceramic bodies is accompanied by a preliminary expansion before shrinkage takes place. This expansion, which has been determined for several types of ceramic bodies, may set up strains and result in the cracking of large pieces when they are improperly fired. A firing schedule that will lessen the strains and eliminate the cracking has been effected and is described in this paper.     

现代陶艺之低温烧

现代陶艺低温烧造技术的成熟作为现代陶艺发展的一个重要方面,不仅颠覆了传统陶艺的烧成模式,更带来了适应现代视觉经验的审美选择,如今它已经成为国际陶艺界的流行语汇。从现代低温烧陶艺的历史、发展以及主要工艺等方面进行了阐述。