RELATION OF METAL THICKNESS,ENAMEL THICKNESS,AND BOTTOM RADIUS TO IMPACT RESISTANCE OF PORCELAIN ENAMELED UTENSILS*

Three series of standard two-quart pudding pans of different metal thicknesses, coated with one, two, and three coats, respectively, of enamel were tested for impact resistance, using the Enameled Utensil Manufacturers' Council standard impact test. The impact resistance of the pans was increased with increase (1) in metal thickness of the pans, (2) of the enamel thickness, and (3) in the size of the bottom radius. The size of the chip formed on impact also increased with increase in enamel thickness. The literature dealing with the fracture of glass and enamels is reviewed, and the factors influencing spontaneous chipping and chipping caused by bending and impact are discussed.     

ABRASION RESISTANCE OF PORCELAIN ENAMELS*

The abrasion resistances of enamels, differing in composition and properties, were determined by the test for resistance of porcelain enamels to surface abrasion (a standard of the Porcelain Enamel Institute, March, 1942). Four to five classes of abrasion resistance were obtained, but for the most part, the results fell within relatively narrow limits. Differences in abrasion index, in general, were not distinguishable by visual inspection. No one class or kind of enamel was superior. While changes in abrasion index were affected by changes in frit formula, it seems that many compositions will give comparable results.     

INVESTIGATION OF ABRASION RESISTANCE OF VARIOUS REFRACTORIES*

This paper describes a new abrasion test for re-fractories consisting of a controlled sandblasting operation wherein various brands of brick were tested. Graphs show correlations for abrasion loss per hour against other properties for the brands tested. Data and charts which compare this abrasion test with the A.S.T.M. rattler test for paving brick are also included.     

TESTING OF CHROME-MAGNESITE BRICK FOR RESISTANCE TO IRON OXIDE BURSTING *

The probable mechanism of the iron oxide bursting of chrome-magnesite brick is discussed. An attempt was made to duplicate this effect in the laboratory. Results indicate that the bursting can be simulated in a laboratory experiment providing the atmosphere of the furnace is such that the penetrating iron oxide liquid is rich in magnetite. A test is proposed for characterizing the bursting resistance of various brick.     

EFFECT OF ZIRCOPAX ADDITIONS ON ABRASION RESISTANCE AND VARIOUS PROPERTIES OF SEVERAL GLAZES*

A test method is described and the results of four series of experiments are given for the empirical evaluation of the effect of Zircopax in improving the resistance to abrasion of glazes. Simultaneous resistance to crazing and the effect on gloss, color, and opacity are noted.     

FACTORS AFFECTING THE RESISTANCE OF SILICA REFRACTORIES TO ABRASION1

The resistance to abrasion is tested by grinding a groove in the surface of the refractory by means of a carborundum wheel with suitable mounting. Other methods used in the tests are discussed. Factors affecting resistance of silica brick to abrasion are porosity and degree of burn. Porosity is affected by grind, quality of ganister, per cent lime and workmanship. Data are given showing a rough relation between length of groove, porosity and burn.     

ABRASION OF GLASS AS RELATED TO COMPOSITION *

The abradability of glass of different compositions was estimated by grinding on a steel plate with powdered quartz as an abrasive, determining the weight removed from the ends of glass'rods, reducing this to volume, and comparing with the volume removed from used silica rods by the same treatment. Silica (SiO₂) and B₂O₂ are constituents contributing to resistance to abrasion, while soda, lime, and especially lead oxide produce high abradability. Abradabilities are expressed in numbers referred to silica glass as unity.     

A PRELIMINARY STUDY OF THE RESISTANCE TO ABRASION OF CERAMIC GLAZES,ITS CONTROL AND METHODS OF DETERMINATION1

Two test methods, one using an Ingersoll glarimeter to obtain results of a high degree of accuracy, and the other simpler “alternate method” for plant control, are described in detail. Tests on commercial hotel chinaware showed the average resistance of foreign ware was higher than that of the domestic and the variation from the average was, in general, less. Experimental glazes were prepared to study the effect on resistance, of: (1) varying SiO₂ and Al₂O₃ content, (2) glaze thickness, and (3) firing treatment. Data obtained are insufficient to justify definite conclusions regarding the effect of varying SiO₂ and Al₂O₃, but do show the resistance of well-matured glazes to be inversely proportional to thickness, a decrease in resistance as the tendency to matt increases, a markedly increased resistance by the higher glost fire. That type of body affects resistance less than do glaze composition and temperature of glost fire.     

RESISTANCE OF ENAMELS TO THERMAL SHOCK*

Thermal-shock resistance tests were made on enamels of varying thermal expansions applied on test pans. Increased weight of application and high expansion of the cover coat decreased the thermal-shock resistance, whereas high expansion of the ground coat increased the resistance.     

RESISTANCE OF GLASS TO THERMAL STRESSES*

The theory of stresses introduced in glass by thermal shocks is a matter of fundamental interest to the glass manufacturer. Analysis is complicated by the existence in many cases of unknown degrees of stress relief or transference by flexure. General treatment of these cases is extremely difficult because of irregular or variable shapes. There is, however, a large group of thermal-shock phenomena in which flexure of the piece is not a factor. Complete immersion shocks fall in this category; so also do thermal shocks administered to tubes and pipes, since the cylindrical shape prevents flexure. (There is a small end effect accompanied by flexure, but in practice only a small fraction of breaks originate in the end region.) Many examples of breakage from shocking one side only of a piece are also of this simple type, since maximum tension occurs immediately from pure “stretch” and is greater than subsequent stresses accompanied by flexure. Analysis of the stresses resulting from stretch incurred by thermal gradients has been carried out by many writers for plates and cylinders, and various applications have been made of the results.¹ The calculation of maximum fiber tension, however, is not in itself enough to determine thermal endurance. The duration of the stress also plays an important role. The simplest example of this is the well-known fact that in immersion tests breakage frequently does not occur for an appreciable interval, sometimes several seconds. Yet maximum tension on the cooled surface is almost immediate and falls off rapidly. The importance of duration is pointed out by Schönborn,^1(c) but he does not attempt any quantitative treatment. It is the purpose of the subsequent analysis to incorporate the time of stressing into the discussion of thermal endurance.     

耐磨铝硅酸盐微晶玻璃核化及晶化制度的优化

在确定耐磨微晶玻璃配方范围的基础上，采用DTA，XRD和SEM等测试手段，探讨了工艺参数变化对微晶玻璃耐磨性的影响，且对制备耐磨微晶玻璃的核化、晶化工艺参数进行了优化设计。结果表明：严格控制晶化工艺参数对制备具有良好耐磨性能的微晶玻璃是非常必要的。     

RESISTANCE OF PLATE GLASS TO ALKALINE SOLUTIONS *

The resistance of polished plate glass to sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and sodium pyrophosphate was studied at various concentrations and temperatures. Test results showed (1) that the hydroxides are less corrosive than many alkaline salts; (2) that temperature has a marked effect on the rate of corrosion; (3) that increasing the solution above 10% does not alter the rate of attack appreciably; and (4) that the amount of stain on glass cannot be used as a measure of the amount of attack.     

增强耐磨尼龙6材料的研制

研制了主要用于煤碳工业洗煤厂的脱水筛板的新型耐磨材料。尼龙6虽然具有良好的综合性能,但是用于洗煤厂的脱水筛板时,其力学性能和耐磨性均不能满足产品的使用要求,而且产品易翘曲变形。通过用玻璃纤维、耐磨填料等填充改性,使改性尼龙6的力学性能有较大的提高,摩擦系数仅为尼龙6的四分之一。将改性尼龙6材料制作筛板小样,经煤水混合物的冲刷磨损的模拟试验,其材料的综合性能均满足脱水筛板的使用要求.     

A DEVICE FOR TESTING THE RESISTANCE OF CHINA TO CHIPPING1

The device (shown in the figure) measures the blow required to chip the edge. Results are reproducible to within about 10%, this variation being due to lack of uniformity in the pieces tested. Vitrified china is more resistant to chipping than is semi-porcelain or European true porcelain.     

NOTE ON THE ACID RESISTANCE OF ENAMELED COOKING UTENSILS1

Apparent segregation of the constituents of an enamel under the influence of gravitation. —Experiments with trial pieces with poured samples, and with enameled ware of various mfgr's. showed that the surface of the layer of enamel which is uppermost during firing and cooling is readily attacked by acid, thus indicating, apparently, that the more soluble materials tend to rise to the top of the melt. It is therefore recommended that enameled kitchen utensils be fired in an inverted position. In the discussion by Bryan A. Rice a series of similar experiments are described using small shallow cups. Quantitative tests failed to show any difference in acid resistance and it is suggested that the author's results were due to the nature of the gases in contact with the enamel surface or to volatilization. In his reply the author accepts this explanation of his results.     

RELATION OF THICKNESS TO IMPACT RESISTANCE OF PORCELAIN ENAMEL*

Chipping of porcelain enamel on the flanges of table tops as a result of impact was studied and compared with the results obtained from the Porcelain Enamel Institute tentative standard impact test. A correlation was found to exist between the results using the P.E.I, test on standard 1-in. tubes and those obtained on the corner of a table-top flange. The impact resistance of enamels applied over a radius also increased as the thickness of the enamel was increased.     

耐磨微晶玻璃的组成与晶化特性的研究

探讨制备耐磨微晶玻璃的成分范围及主晶相和晶核剂的选择，在此基础上，采用DTA，XRD，SEM等测试手段分析了材料的晶化动力学、晶相和显微结构。所得到的微晶玻璃的主晶相为透辉石，其组织致密、结构均匀、晶粒尺寸在100nm左右。该材料具有优良的晶化特性，析晶活化能为E=78.81kJ／mol，晶体生长指数为3.01。对该材料与高铝瓷的耐磨性进行了比较，其耐磨性是90％Al2O3瓷球的1．5倍。     

RESISTANCE OF GLASS BOTTLES TO NEUTRAL ALCOHOLIC SOLUTIONS*

Bottle surface tests with alcoholic solutions of various strengths and with distilled water show that corrosion decreases with increasing alcoholic concentration. The tendency to form flakes usually, though not always, decreases with increasing alcoholic concentration. The results show no relation that will hold for all glass bottle compositions between extraction values with distilled water in any accelerated test and extraction values or the tendency to form flakes in neutral alcoholic solutions.     

RELATION OF COEFFICIENT OF EXPANSION TO IMPACT RESISTANCE OF PORCELAIN ENAMELS*

The tentative standard impact test procedure, adopted by the Porcelain Enamel Institute, was used to test and compare cylinders coated with several experimental and commercial enamels. The important facts noted were (1) the effect of cubic thermal expansion on the impact resistance, (2) the importance of the ground coat to the resistance of any one cover enamel, and (3) the wide variation between cover enamels in resistance to impact.