A PROGRESS REPORT ON THE DEVELOPMENT OF AN ABRASION TEST FOR REFRACTORIES AT HIGH TEMPERATURES1

A report of progress in the development of a method of testing refractories for their resistance to abrasion at high temperatures. The method developed consists of a steel chisel point moving back and forth over faces of the brick clamped together. Eleven brick are tested at one time. The chisel is actuated by means of a jack hammer and is water-cooled. The blow delivered vanes from 6.5 inch-pounds at the beginning of the test to 13 inch-pounds under the most severe conditions. The chisel has a rounded point l/8-ch radius and 1 inch wide. Data show that the principle is correct and capable of differentiating between brick of varying resistances to abrasion at tempcratures as high as 1350°C.     

PROGRESS REPORT ON CAST IRON FOR ENAMELING PURPOSES1

Blisters on enameled cast-iron ware may be traced either to faulty enamels and process of application or to the castings themselves. This investigation is concerned with the latter type of blisters. Differences in the blistering tendencies of different sets of castings were clearly brought out by an enameling test which included a variety of firing treatments. Using this test it was found that not only do different irons have different blistering tendencies, but successive heats of the same iron may have different blistering tendencies. The main source of blisters from the irons used in this work was overcome by removal of a thin surface layer of the castings, through either mechanical or chemical means.     

PROGRESS REPORT ON INVESTIGATION OF SAGGER CLAYS1

This paper is the first progress report of a comprehensive study of sagger clays. It includes the results of a preliminary study of clays representative of those used in sagger making throughout the United States. Chemical analyses, and a summary of physical tests, petrographic examinations, and the effect of repeated burns in pottery kilns are given. As a result of this work the clays have been classified into five groups characterized by properties in the fired state. The paper also contains an outline of a proposed intensive and fundamental study of a limited number of clays typical of each group.     

REFRACTORIES FOR OIL-GAS MANUFACTURE1

The present investigations of refractories by the oil-gas industry on the Pacific Coast were stimulated by sporadic independent tests in the past whereby it was observed that different qualities of fire brick not only had varying lengths of service but also had an apparent influence on the amount and quality of gas made and on the efficiency of gas manufacture. The essential differences in generator design, including that of brick-work construction, in the two-shell type of generator as compared with the single-shell generator are such that longer refractories life is obtained in the former type. The operations in the manufacture of oil gas for the two-generator types are briefly discussed, showing that the refractories are subjected to alternating oxidizing and reducing conditions. Other causes contributing to ultimate refractories failures are carbon deposition in the brick, abrasion of hot gases and the impinging of long flames on the brick, heavy checker-brick loads on arches, faulty construction of arches, and erratic working conditions. In addition, super-saturated steam, heavy hydrocarbons, and salts and sulphur in the oil, are contributing causes to checker-brick disintegration, especially in the generator zones where the oil and steam are introduced. It is hoped that specifications for refractories may be drawn up from the results of practical service tests now being conducted. The heat-transfer and heat-absorption properties of various refractories, such as conductivity, specific heat, density, diffusivity, heat capacity, and time required for the refractories to reach near-heat saturation, are discussed, particular attention being given to their possible application as oil-gas generator checker brick. The need for more complete and accurate data on the fundamental constants necessary in heat-transfer calculations is pointed out. Researches on refractories with thermal properties superior to fire brick are now being conducted in generators in an endeavor to increase gas capacity and operating efficiency along the lines indicated by theoretical considerations.     

REFRACTORIES FOR FLAT ARCHES1

Arch construction is discussed, describing present method of placing fire clay tile. Tile are suspended on cast iron hangers by means of a tee-shaped slot molded in the top end of each tile, giving room for expansion in every direction. Larger quantities of heat units are released, more intense chemical reactions and there is ample shearing strength and small loss from weight or pressure.     

PRODUCER GAS FOR BURNING REFRACTORIES1

History of installations in the United States of producer gas for burning fire brick. Causes of failure or abandonment of producer gas firing. Continuous regenerative kiln necessary for successful burning at high temperatures with producer gas. The compartment kiln, fired with producer gas, best adapted for general refractories. Advantages of the compartment kiln over the car tunnel kiln. Essential features of continuous kilns for the successful burning of refractories. Special features of gas producers for ceramic kilns. Temperatures from producer gas. Economy of producer gas as compared with natural gas, oil and powdered coal. Investigation of designs and methods of operating gas producers.     

NOTE ON REFRACTORIES ENGINEERING1

A brief outline of training necessary to fit one for work as a Refractories Engineer. Nature of the work, its present-day importance and one verbal illustration of the work of such an Engineer.     

SILICON-CARBIDE REFRACTORIES FOR WATER-GAS GENERATORS1

A discussion of the problems involved in water-gas generator refractories is given and the steps in the development leading to the present highly satisfactory silicon-carbide air-ventilated Bernitz type blocks are given. Actual operating costs of typical installations are given. It is shown that generator capacities have been increased as much as 50% and fuel reductions have been so large that a real saving in net operating costs has resulted from the installation of this-type of lining. Many generators have now been lined and economically operated with air ventilated silicon-carbide blocks.     

PROGRESS REPORT ON THE EFFLORESCENCE AND SCUMMING OF MORTAR MATERIALS1

A general discussion is given on soluble salts in clays, clay products, and mortar materials and on the addition of barium compounds to make the salts insoluble. Twenty-one, 4- × 4-foot panels, 8 inches thick were constructed of the same glacial-clay, red, face brick with variations in the following common mortar materials: sand, slaked lime, hydrated lime, and Portland cement. Saturated brick was tried versus dry brick; sea water was used to replace fresh water; machine-mixing of the mortar batch was tried against hand-mixing; and various percentages of barium carbonate, barium hydroxide, and barium chloride were introduced to make the calcium sulphate insoluble. Temporary scum or that obtained in the original drying of the wall was noted and later or permanent scums, produced by artificial and natural soaking and drying the walls were studied for over a year. Results All the mortars studied can be made to scum if sufficient water and time of contact of water and mortar are provided. The troublesome salts are: (1) calcium sulphate largely introduced by the Portland cement, which makes a very bad, early scum; (2) calcium hydroxide from the free lime and hydrolyzed calcium aluminates and silicates in Portland cement and from uncarbonated lumps of lime in the lime mortars; in addition, some minor salts from special sources, such as sodium chloride from sea water Lime mortar streaks were only produced after a large quantity of water had been washed through the panel, and were apparently formed by finely divided or colloidal lime hydroxide or carbonate in suspension in the water running from the porous mortar down the side of the wall. This is a very severe soaking condition and is not common in the ordinary building wall. The lime sulphate dissolves readily enough to pass in solution through the pores of the brick and t o spread uniformly over the brick surface. Lumps of hardened lime should he removed from both slaked and hydrated lime to prevent streaks of lime hydroxide and carbonate on the surface under wet conditions for long periods of time. Lumps of lime also produce spalling. The interior of a wall should be well protected from leaky drains, gutters, etc., which permit water to get inside. A hard rain of short duration is not as bad as a long, soaking drizzle which permits the water t o remain in contact with the mortar for a longer period of time. Cement products, such as artificial cement stone, commonly release salts which drain onto other facing materials. The tests indicated that barium carbonate is effective under normal conditions in preventing or minimizing calcium sulphate scum from Portland cement. This has been checked on large Seattle school buildings where the conditions are favorable for scum. Five per cent barium carbonate in terms of Portland cement has been used successfully. I t has been suggested (but not tried) that diatomaceous earth may combine with the free lime of the mortar materials to produce a more insoluble calcium silicate and reduce the temporary scum of lime hydroxide. The study is being continued on the chemical analysis and composition of the scums taken from the surface of the walls and leached in the laboratory from separate batches of the mortar materials. Preliminary analyses have already been made. The strength of the mortar materials to note the effect of barium salts is also under study. No deleterious effects have been found from barium salts.     

PROGRESS REPORT ON RESEARCH OF PAVING BRICK FROM IOWA SHALES1

Test on full size pavers made from 11 shales showed that five would make an excellent paving material and others had possibilities of making a block that would give service. Various processes were tried as soft-mud, roller expression machine, dry-press, and a new belt machine, also additions of magnesium and colloidal materials. The soft-mud, roller expression machine gave equal if not better results than the stiff-mud process, and the other processes required higher temperatures to get a suitable block for test. Magnesium reduced the rattler test from 27% to 22% and changed the color to buff similar to that of fire clay. The colloidal materials made the shale more refractory and hence the brick were too soft for the rattler test. ² 2 The American Society for Testing Materials has not given any definite specifications in regard to results required of the rattler test, leaving this to be decided by local conditions. However, they give the following for maximum permissible loss and the general average loss in this test.
     

THE EFFECT OF ATMOSPHERIC CONDITIONS ON THE LOAD TEST FOR REFRACTORIES1

The literature relative to the investigation was reviewed and criticized. Iron pyrite was added to clays in amounts varying from 0 to 5%. Test pieces 2×2×41/2 inches were fabricated by the stiff-mud, and dry-press processes. After firing to cone 8 these were subjected to load tests at 1350°C under oxidizing, neutral, and reducing conditions. Expansion and contraction values were plotted against time and temperature. Results under reducing conditions. Expansion and contraction increased with increase of pyrite content.     

A SERVICE SPALLING TEST FOR REFRACTORIES1

Brief comments are made on various spalling test methods and the shortcomings of these when used as suitability tests. An outline is given of the development of a service spalling test which was designed to simulate as closely as possible the conditions encountered in furnaces where spalling is important. The test differentiates between structural and thermal spalling and this is desirable because each type is caused by different conditions in service and is resisted by distinctly different properties in refractories. The data obtained in developing the test show the importance of wall thickness or the degree of insulation on the spalling of refractories in service.     

REQUIREMENTS OF REFRACTORIES FOR ELECTRIC FURNACES1

This article is essentially a survey, giving, however, not generalized statements, but a definite discussion of the refractories problems now existing in the important electric furnace processes. After summarizing some of the general refractory requirements of electric furnace work, the author discusses the specific conditions and refractory requirements in steel, iron, and non-ferrous metal melting, smelting furnaces for producing iron, ferro-alloys and calcium carbide, anti in furnaces for melting refractory materials. The article closes with a summary of outstanding present developments. Varied conditions probably make an ideal, universal refractory almost impossible of attainment. The relatively cheap refractories standardized in fuel-fired furnaces have been very largely used in electric furnaces. There is, however, a growing use for specialized “super-refractories,” even at greatly increased cost, that will stand various especially severe conditions in certain kinds of work. Important recent developments are higher firing temperatures, the use of high aluminous fire clays, and increased experimental work on fused refractories. The commercial production of sufficiently high firing temperatures, and the development of satisfactory bonds for special refractories are at present perplexing problems.     

REFRACTORIES FOR STOKERS

An outline is given of the general uses of refractories for stokers, and the requirements for an ideal fire brick. Temperatures which a refractory must stand are given and some of the troubles due to fluxing and spalling are described. Some analyses are made of typical brick and troublesome ash.