ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1959.tb14065.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

In commercial practice, where temperatures are low, a number of commercially available materials are satisfactory as a container for molten aluminum. None of these, however, resists attack by aluminum in the temperature range 1800° to 2000°C. An investigation was conducted to find a material completely inert to aluminum at these high temperatures. Aluminum nitride emerged as the material that was inert to aluminum and showed satisfactory properties as a ceramic material. A method of preparing high‐purity AIN by striking a d.‐c. arc between two high‐purity aluminum electrodes in a nitrogen atmosphere is described. A refractory having excellent strength and low porosity was achieved by hydrostatic pressing and firing at high temperatures. The mechanical, electrical, thermal, and chemical properties of the refractory are di

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1959.tb14066.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

The effect of cerium oxide incorporated as the principal opacifying agent in the frit batch on the properties of white cover‐coat porcelain enamels was studied. The effect of several variables on the opacity of the enamel was investigated as a function of firing temperature. Variables studied included(a)the amount of cerium oxide added,(b)the manner in which cerium oxide was incorporated into the enamel, i.e., mill addition, frit addition, or combination of both,(c)composition of the base glass,(d)weight of application, and(e)type of mill addition. Porcelain enamels were produced which had good acid resistance, high gloss, and a reflectance of 80% or more. Mill‐added cerium oxide seemed to be less effective than that which was incorporated in the porcelain enamel as a component of the frit. The spectrophotometric analysis indicated good color stability of cerium oxide enam

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1959.tb14067.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

The characteristic minimum which occurs in the apparent viscosity‐pH curves for oxide slips is explained in terms of the zeta potential of the dispersed oxide. The model adopted also explains a number of other features of the rheological behavior of oxide slip

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1959.tb14068.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

A preliminary study of the system Tho2‐SiO2supported the premise that the system CaF2BeF2is a model for this silicate system. The only compound present was the monoclinic form of ThSiO4(huttonite), which melted incongruently to Tho2and liquid at 1975° f 50° C. as determined from a series of powder X‐ray spectrometer patterns. The eutectic temperature as tentatively determined is 1700°± 10°C. at a composition of greater than 95% by weight of Sio2. No solid‐solution areas were observed. The quenching samples were fired in a modified oxygen‐acetylene furnace which was developed to insure accurate temperature readings and to retain the effects of heating the sa

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1959.tb14069.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

A new crystalline variety of B2O3has been prepared at pressures above 22,000 atmospheres and above 400°C. The properties are listed. These moderate pressures also are sufficient to catalyze the crystallization of the more common hexagonal form from B2O3glass. Pressures, however, of up to 50,000 atmospheres will not convert GeO2quartz to GeO2rutile at room temperature. From the infrared absorption patterns of appropriate phases it can be shown that in coesite the tetrahedral coordination of Si4+(or Be2+in the model BeF2‐coesite phase) must be unchanged. In the new form of B2O3, however, the coordination number must be substantially different from that in the common hexagonal B2

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1959.tb14070.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

Glasses within the ternary system Li2O‐B2O2SiO2containing less than 25.6% Li2Ocan be broadly classified into three groups according to their behavior during cooling or heating. One group, containing either more than 18% Li2Oor less than 20% SiO2, yields clear glasses during slow or rapid cooling. The second group, containing approximately 5 to 15% Li2O and 26 to 90% SiO2, yields dense white opal glass during slow or rapid cooling. The third group, located at the outer edge of the second group, cools to room temperature as clear glasses but develops opacity when reheated to temperatures between 550° and 8800°C. It has been shown by electron microscopy that the opacity is due to liquid immiscibility, the matrix glass containing well‐formed spheres of the dispersed phase. Some of the clear glasses of both groups have been shown to consist of two immiscible phases. The size of the dispersed units in the spontaneous opal glasses and also the reheat opal glasses can be controlled by the variation of the reheat treatments. The phase separation reported here is beyond the resolution of the petrographic microscope and can be detected only with the high resolution of the electron microscope. Accessory evidence is given to show that the phases are non‐crys

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1959.tb14071.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

Fourteen selected metal ions were added to magnesium basic carbonate, and the MgO obtained after calcining was fired at various temperatures to determine the effect of the additives on the sintering behavior. The magnesia without additives showed rapid increase in density with firing temperature near 1200° C. The majority of the additives caused increased density, at a given firing treatment, but some were without effect and one (Cr) dramatically inhibited sintering in certain percentages. It is believed that most of the additives which aided sintering did so by entering into the magnesia lattice and creating defects, although at least one (V) clearly promoted sintering by liquid formation

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1959.tb14072.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

Mixing influences that are effective during the flow of glass through continuous tanks are classified. Common experimental techniques for evaluating these influences are compared. A multi cell model is used to describe flow behavior in the absence of miring from transfer flow. Laminar transfer flow in a glass tank is evaluated by considering flow through an open channel with a vertical viscosity gradient. Recently published results describing flow through a container glass tank at relatively high pulls are best explained by secondary flows modifying the mixing effects from the variable velocity of laminar transfer flow through the tank.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1959.tb14073.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

Further studies were made on the effect of the nature of the atmosphere on the wetting of gold and platinum by sodium disilicate at 1000°C. The gases were oxygen, nitrogen, carbon dioxide, helium, argon, water vapor, carbon monoxide, hydrogen, and several mixtures of some of these gases. Data reported were obtained in the pressure range 10‐5mm. of Hg to approximately 1 mm. of Hg. A special experimental apparatus was constructed for this purpose. In this pressure range the results showed that the wetting of gold was unaffected by these atmospheres. The platinum‐sodium disilicate contact angle, on the other hand, depended on the nature and pressure of the gas. This angle was affected most by atmospheres of water vapor, carbon monoxide, hydrogen, and oxygen. Water vapor was found to be easily displaced from the metal by oxygen. The results were interpreted on the basis of selective adsorption of the gases at the various metal interfaces and of absorption of oxygen and hydrogen by plat

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1959.tb14074.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY