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.     

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 SHALES AND BRICK CLAYS OF GEORGIA*

A résumé is given of the geology, general ceramic properties, and uses of the shales and alluvial clays of Georgia, based on a study by the Georgia Geological Survey. The conclusions were derived from seven months of field work and from ceramic tests on 115 samples from private properties and active plants.¹     

COMPARATIVE TESTS OF SOME AMERICAN AND GERMAN FIRECLAY BRICK1

The Bureau of Standards has recently completed a short investigation comprising comparative tests of five brands of German-made brick and six brands of American-made brick. The results indicate that the Ge man-made brick are practically the equal of the American brick.     

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.     

X-RAY INVESTIGATION OF THE EFFECT OF HEAT ON CHINA CLAYS1

X-ray diffraction patterns were obtained from an English china clay and a Georgia sedimentary kaolin, both raw and fired to various temperatures. The chief crystalline constituent of the raw clays was found to be kaolinite. Upon dehydration the kaolinite lattice was destroyed and the clays gave no diffraction pattern. Mullite was formed in both clays at 950°C and the amount increased with increase of firing temperature. In addition to the mullite, free alumina was present in the Georgia clay from 950 to 1100°C and cristobalite at temperatures above 1200°C.     

EFFECT OF THE SULFATE ION ON THE PLASTICITY OF BRICK CLAYS*

Two red-firing Iowa brick clays were analyzed for sulfate (SO₄⁻) content by a method suitable for plant-control tests. From this datum the amount of barium carbonate required to react with this ion can be calculated. Plasticity measurements on (1) samples treated with the amount of barium carbonate indicated by SO₄⁻ analysis, (2) untreated samples, and (3) samples treated with normal plant additions show significant differences in this property. These differences can be explained using the modern concepts of the factors which influence the zeta potential.     

PROGRESS REPORT ON INVESTIGATION OF SAGGER CLAYS. V. Preparation of Experimental Sagger Bodies According to Fundamental Properties1

This is a Fifth Progress Report giving the results obtained in a preliminary study of sagger bodies, which is a continuation of an extensive investigation of sagger clays for the purpose of determining the properties of clays and bodies best suited for sagger purposes. The report contains data on the modulus of elasticity, transverse breaking strength, plastic flow, thermal expansion, and resistance to failure due to heat shock of 55 sagger mixes representing 39 different bodies fired at either 1230°C or 1270°C. The 16 bodies prepared in duplicate were tested both after firing at 1230°C and 1270°C. All of these bodies were compounded with two clays whose properties are given in earlier progress reports, and a mixture of graded grog. The grog was graded into sizes so as to result in two types of bodies, those having (1) a coarse and open-grained structure and (2) a dense and fine-grained structure. The data on the fired bodies show that those containing the fine sizes of grog have the higher modulus of elasticity, transverse strength, and in the majority of cases, thermal expansion. Very little difference in total porosity of the two types of bodies is indicated although the rate of absorption shows large differences. The data obtained in this preliminary study indicate that those bodies having (1) a porosity of less than 25% (2) a low modulus of elasticity, (3) as high transverse strength as is compatible with the low modulus of elasticity, and (4) low thermal expansion below 250°C are the most desirable for sagger purposes.     

PROGRESS REPORT ON INVESTIGATION OF SAGGER CLAYS. VI The Life of the Sagger as Affected by Varying Certain Properties1

This report presents the results obtained in a study of sagger bodies and represents an enlargement of a similar study of a preliminary nature, the results of which have been published. The clays and grogs are combined to give bodies having wide variations in body structure and in the several properties which were studied. Data are given on the modulus of elasticity, transverse breaking strength, plastic flow, thermal expansion, and resistance to failure due to heat shock of thirty-five laboratory prepared bodies and ten commercial bodies after firing at from one to three different temperatures. For comparative purposes data are given on two series of bodies, the one series containing coarse grog and the other fine grog. In addition body compositions were varied in order to compare the effect on sagger life of using open- and close-firing grogs.     

THE MINERALS OF BENTONITE AND RELATED CLAYS AND THEIR PHYSICAL PROPERTIES1

Bentonite is a very widely distributed clay material that is the result of the devitrification and chemical alteration of glassy volcanic ash or tuff. Bentonite should be used as the name of a rock derived from volcanic glass and it is commonly composed of the mineral montmorillonite but less often of beidellite. Its characteristic minerals are completely crystalline and have a micaceous habit, high birefringence and facile cleavage. It contains no gel colloids, and few of its crystal particles are so small as to reach “colloidal size.” It shows high adsorptive powers and this property is more dependent upon physical form than upon chemical composition. That is upon the micaceous structure and easy cleavage which give very great surface area and the‘felt-like texture which facilitates permeability. The clay minerals of the type here described resemble the micas in many ways, but do not seem to possess the marked chemical variability of that group. A large number of analyses of the clay minerals from bentonite indicates that the most widespread of these is montmorillonite with the formula (Mg, Ca)O A1₂0₃ 5SiO₂, nH₂0. A reanalysis of the type montmorillonite from Montmorillon, France, gives the same formula, and the mineral has also been recognized in lithium-bearing pegmatites and in fullers' earth. A few bentonites are composed of beidellite, a mineral first identified from the gouge clay of ore veins. It has the formula A1₂O₃·3SiO₂·nH₂O where n= about 4, and A1₂0₃ may be partly replaced by Fe₂0₃. A third micaceous clay mineral has the composition of halloysite Al₂O₃· 2SiO₂· nH₂O, but it is completely and visibly crystalline and has a high birefringence.     

INVESTIGATION ON ENAMEL CLAYS1

Functions of clay in enameling and requirements of enamel clays are enumerated. The investigation deals with twelve representative enamel clays, which were examined for water of plasticity, drying shrinkage, modulus of rupture and properties when fired to 1000°C. Using these clays in enamel slips, viscosity, suspension test, and hydrogenion concentration by the indicator method were run. Fineness test, petrographic examination and chemical analyses were made on the clays. They were then tested in a cover coat enamel, subjecting the test pieces to impact test and thermal shock. The results of all the tests are summarized and conclusions drawn therefrom.     

THE MAKING OF DOLOMITE BRICK AND A STUDY OF THEIR PROPERTIES1

This investigation deals with the making and the properties of dolomite brick. A thorough review of the literature shows that there are many improvements possible in the making of dolomite brick and some of the principal faults are pointed out. In this investigation it was shown that 200-mesh dolomite mixtures of a composition 9–0–6M (9% Fe₂O₃–0% Al₂O₃–6% SiO₂–85% dolomite); 6–3–6M (6% Fe₂O₃–3% Al₂)₃–6% SiO₂–85% dolomite); and 2–4–4M (2% Fe₂O³–4% Al₂O₃–4% SiO₂–90% dolomite) can, if calcined to cone 20 down, be made into better brick than any previously described. The advantages of this higher fired material are (1) it has been more completely shrunk than that fired at lower temperatures and therefore does not shrink as much when refired in the form of brick, (2) in the use of aqueous binders less trouble is encountered due to slaking than with the lower fired material. In a continuation of the binder studies a thorough investigation was made of molasses, tar, epsom salts, water and carbonated water. No conditions were found where water, carbonated water, bindex or epsom salts, could be satisfactorily used. Using 20-mesh (2–4–4M) calcine and 15 and 20% of molasses as a binder it was found that the brick always squatted considerably at about cone 15 down. This was shown to be inherent in the material itself and not due to a migration of any part of the material or a softening of the molasses. The most successful brick were made using 20-mesh D9-0-6M composition (9% Fe₂O₃–0% Al₂O₃–6% SiO₂–85% dolomite 200-mesh calcined to cone 20 down), plus 13% of a one to three dextrin-water mixture as binder, and 20-mesh S6–3–6M (6% Fe₂O₃–3% Al₂O₃–6% SiO₂–85% dolomite 200-mesh calcined to cone 20 down), plus 12% of a 5% solution of sodium silicate and in each case fired to cones 16 to 18 down. These brick are dense, well shaped and refractory. Cone fusion temperatures of calcines 9–0–6M, 6–3–6M and 2–4–4M were made in an especially constructed oxyacetylene furnace. The results of the tests show that the above compositions have cone fusion temperatures above cone 40 (2010°C) down. In connection with this work it was also shown that an electric induction furnace, where graphite is used as the resistor, is not reliable for cone fusion tests due to the strong reducing atmosphere. In a load test on brick D9–0–6M and S6–3–6M it was found that when they are heated to 1350°C and held at 1350°C for one hour under a load of twenty-five pounds per square inch they show only a small compression. Brick D9–0–6M shows a compression of 3% while S6–3–6M shows a compression of 0.9% neither brick showing any tendency to crack or squat. In a spalling test these brick (D9–0–6M and S6–3–6M) were shown to possess the characteristic fault of magnesite in that they do not withstand sudden heat change without spalling. On heating one hour a t 1350°C and then exposing to room temperature they crack badly. The use of less flux was unsuccessful as the material thus prepared shows strong hydration which is fatal in that it causes the material to disintegrate. Dolomite compositions 9-0-6M, 6-3-6M and 2 4 4-M, flux violently with silica and fire brick but are inactive toward magnesia and chrome brick. It is, however, possible to burn the dolomite on fire clay brick if a thick layer of magnesia brick grog is used. Since it is necessary to grind the dead-burned dolomite before it can be made up into brick i t is necessary to know the relative tendency toward slaking of the various size particles. It was found that the finer the calcined dolomite is ground the more rapidly the slaking takes place and that it is in some cases very appreciable for 20-mesh material as used in making brick.     

PROGRESS REPORT ON THE EFFECT OF FURNACE GASES ON THE QUALITY OF ENAMELS1

The appearance of sheet-steel enamels fired in atmopheres of nitrogen, carbon dioxide, sulphur dioxide, and Urbana city gas has been determined. A study of the effect of variations in the composition of sheet-steel ground coats and sheet-steel cover coats on their resistance to attack by sulphur gases has been made. Plans for future work on the problem are outlined.     

PROGRESS REPORT ON THE STUDY OF GASES IN ENAMELING IRON*

Since all ferrous materials contain within their structure a varied assortment and quantity of gases, a discussion is presented of the effect of such factors as time, temperature, atmosphere, and deliberate methods used in the manufacture of enameling iron. A study of the important gaseous impurities in ferrous materials is given. Melting investigations were made to deterrninc at high temperatures the absorptive capacity of specially prepared irons for air, nitrogen, hydrogen, and carbon monoxide, and the influence of carbon, manganese, silicon, and aluminum on the absorptive and retentive capacities. Manganese in increasing amounts increased the absorption of all gases. A critical percentage content of 0.25% of manganese was found to exist, at which maximum absorption of nitrogen occurred; below and above this percentage content the absorption of nitrogen decreased. Many grades of enameling iron were subjected to a similar investigation. Certain irregularities of various analyses of commercial irons were noted in that there were irregularities of absorption and retention of gases in a range of temperature which included the temperature at which porcelain enamels were fired. The enameling iron of low carbon and low manganese content, containing only the permissibly low phosphorus, sulfur, silicon, and alloying elements, should insure dependable performance during enameling operations.     

我国纳米塑料研制进展

综述了我国纳米塑料(包括聚乙烯、聚丙烯、聚氯乙烯、聚对苯二甲酸乙二醇酯、聚对苯二甲酸丁二醇酯)的研制、性能及应用。