THE EFFECT OF GLAZE COMPOSITION ON THE CRAZING OF TERRA COTTA1

Comparing the effects of equal molecular additions of the various components of the glazes in this study, it was found that ZnO and feldspar overcome crazing, ZnO being the more effective. MgO, BaO and CaO tend to produce crazing, MgO having the greatest tendency and the effect of BaO being somewhat greater than that of CaO. SnO₂ has no effect on the crazing. Increase of clay is more effective in overcoming crazing than any other changes that can be made in the glaze formula. Addition of small amounts of clay are more effective in overcoming crazing than much larger additions or substitutions of the other components. Increase of flint (per molecular equivalent) is less effective in overcoming crazing than increase of either clay, ZnO or feldspar, although, generally, considerable more flint than clay or ZnO can be added without appreciably changing the maturing point of the glaze. In many cases, increase of flint will not overcome crazing in a glaze.     

高温热处理温度对PAN基碳纤维结构和力学性能的影响

考察了热处理温度对ＰＡＮ基碳纤维结构和力学性能的影响，为进一步提高碳纤维的力学性能提供了理论依据。     

EFFECT OF HEAT-TREATMENT ON THE DENSITY AND CONSTITUTION OF HIGH-SILICA GLASSES OF THE BOROSILICATE TYPE*

Some evidence leading to the supposition that certain borosilicate glasses containing a high percentage of silica are made up of two-component glasses is presented. One of these components, which consists mainly of silica and has a low expansivity, forms a rigid network throughout the body of the glass while the temperature is still high enough to maintain the other component in a liquid state. At lower temperatures, the latter component also forms a rigid network that is intricately entwined with that of the high-temperature component. The composition of the network that forms at relatively low temperatures is presumably not unlike that of a borosilicate glass containing a moderate percentage of silica. Consequently, the expansivity of this low-temperature component is definitely higher than that of the other. Because of the difference between the expansivities, the low-temperature component, as soon as it behaves as a rigid network on cooling, compresses the high-temperature network and is correspondingly distended. By cooling very rapidly, these elastic strains are developed at temperatures within and even above the upper part of the annealing range of the low-temperature component. When such strains are developed at high temperatures, they are relaxed by heat-treatments at lower annealing temperatures, and this relaxation causes an expansion of the undercooled glass while at a constant temperature. However, in the early stages of the treatment, the expansion caused by the relaxation of the strains may be overshadowed by a contraction that results from the shrinkage of the low-temperature component as it approaches equilibrium from its undercooled condition. These concepts concerning the constitution of borosilicate glasses that contain a high percentage of silica are used to explain the very unusual density changes that are observed when these glasses are subjected to heat-treatments at different annealing temperatures.     

热缩聚工艺条件对中间相炭微球形成的影响

以中温煤沥青为原料采用常压热缩聚工艺制备中间相炭微球。考察了不同聚合条件对中间相炭微球收率及形态的影响,从而找出制备中间相炭微球的最佳工艺路线。     

颗粒度对硅砂成份和熔化影响的探讨

通过对硅砂颗粒度的分析,介绍了硅砂成份与颗粒度的关系,说明了硅砂对熔化的影响.     

工艺对玻璃/钙长石材料性能的影响

设计CaO-Li2O-B2O3-SiO2-Al2O3玻璃/钙长石与堇青石、熔融石英、莫来石的复合,研究了它们对材料性能的影响,并探讨了工艺条件对玻璃/陶瓷复合材料性能的影响,制备了具有低温、低介与硅相匹配的低热膨胀系数的新型的复合材料。     

THE EFFECT OF DIFFERENT BODIES ON SOME WETTING AND FLOW CHARACTERISTICS OF GLAZES *

Variations in the fluid properties of glazes produced by different bodies were studied, and several methods for testing the wetting ability of the glazes were compared. An angle-of-contact method was found best for measuring the ability of glazes to wet bodies. It was found that different bodies had varying effects on the fluid properties of a glaze. The maturing temperatures of a glaze are not fixed for a given glaze but may vary as much as four cones on different bodies, if wetting ability is considered in determining this temperature.     

A STUDY OF THE ABSORPTION OF TWO EARTHENWARE BODIES AND THEIR RESISTANCE TO CRAZING IN THE STEAM TEST1

An ivory and a white earthenware body fired in different positions of periodic and tunnel kilns and maturing to various absorptions were subjected to autoclave steam treatments at the pressures of 100 and 150 lbs. per sq. inch. The ivory body resisted the crazing induced by this test for absorptions from 7 to 8% in the 100-1b. pressure treatment. The white body withstood the destructive effect up to an absorption of 8.5%. Within a narrow range, thorough glost firing had some effect in increasing the resistance. In the 150-1b. test, the critical resisting absorption was lowered to 6% for each body.     

热处理温度对C／C复合材料摩擦磨损性能的影响

利用销一盘式摩擦磨损试验机研究了不同热处理温度制备C／C复合材料与GCrl5钢配副在油润滑务件下的摩擦磨损行为。结果表明,在油润滑条件下,材料摩擦系数低,其值在0．06～0．17范围内,磨损率在（1．03～2．56）×10^4mg／N·m范围,其中2100℃热处理的材料具有最低的摩擦系数和磨损率。在摩擦试验过程中,2000℃以上热处理的材料可以形成完整致密的摩擦膜,能起到润滑作用。结果还表明,随热处理温度的提高,材料石墨化程度提高,硬度降低,其磨损机制以磨粒磨损为主转向以疲劳磨损和粘着磨损占据主导地位。     

热处理温度对MoO_3薄膜的结构及光致变色性能的影响

采用溶胶-凝胶浸渍提拉法制备MoO3光致变色薄膜。用色差计表征了材料的光致变色性能,并结合X射线衍射、扫描电镜、紫外-可见吸收光谱研究了热处理温度对其微观结构及性能的影响。结果表明:制备的产物为斜方相MoO3;随热处理温度的升高,MoO3薄膜光致变色性能先增后减。当温度为500℃时,薄膜的结晶度最大,颗粒粒径最小,比表面积较大;色差值最大为1.2330。在该温度下激发波长向长波长移动,薄膜的吸收光波区域变宽,从而使MoO3薄膜的光致变色性能提高。     

合成方法对Span产品的结构和组成的影响

采用高效液相色谱（ＨＰＬＣ）对一步法工业品、分步催化法和两步法国外样品进行组成分析，考察了不同合成方法对产品的组成及结构的影响。     

EFFECT OF VARIOUS GASEOUS ATMOSPHERES ON THE VITRIFICATION OF CERAMIC BODIES*

Various types of ceramic bodies were fired in atmospheres of O₂, N₂, CO₂, H₂, and H₂. A marked increase in the rate of vitrification occurred when bodies containing feldspar were fired in an atmosphere of H₂O. This effcct was explained on the basis of a feldspar-water eutectic.     

OBSERVATION ON THE EFFECT OF SILICON CARBIDE IN CLAY BODIES1

In these studies the distinction is made between silicon carbide in a clay body and clay-bonded silicon carbide. An increase of strength by replacement of grog particles was noted. Tests were made on various bodies containing as little as 10% Sic by weight and up to 67% by weight. Comparison of clay and grog bodies, clay grog, and SiC bodies, and clay and SiC bodies were carried out under the load-span test at various temperatures. The resistance of bodies containing SiC to the corrosion effect of various slags, particularly iron oxides with alkalis and alkaline earths, is given. A comparison is made with clay-grog bodies. The increase of conductivity of bodies containing SiC is apparent. Commercial application of SiC and clay bodies is discussed.     

THERMAL SHOCK EFFECT ON THE TRANSVERSE STRENGTH OF CLAY BODIES1

Test specimens of twenty commercial shale and fireclay bodies, ranging in softening point from cones 7 to 30, were fired in laboratory kilns to cones 04, 2, and 6. Comparisons of transverse strength before and after thermal shock were made, thermal shock h a i h g been produced by eight cycles of heating in a furnace at 1100°F for 15 minutes and cooling over an air blast for an equal length of time. Results indicate that as initial strength increases, per cent reduction in strength increases and strength after thermal shock increases to a maximum and then declines. Curves are fitted to the data and the mathematical relationships are shown. The results of other investigators are discussed.     

OBSERVATIONS ON THE PROPERTIES OF CLAYS AND CLAY-GROG BODIES

Determinations of shrinkage, absorption, and transverse strength were made on a series of clays and clay-grog bodies fired together. Highly porous grog bodies are obtained with tight burning clays when the latter possess high shrinkage. This is due to the formation of crevices between the clay and grog particles, and to produce a tight grog body the clay must be of low shrinkage and low porosity.     

改性膨润土对轮胎半成品胶料性能影响的研究

在轮胎的内层胶、缓冲胶中加入5－10份改性膨润土,不影响轮胎半成品的力学性能,而且有助于改善胶料的加工性能,提高胶料与骨架材料的粘着强度。     

EFFECT OF EXCHANGEABLE BASES ON ABSORPTION AND TRANSVERSE STRENGTH OF CLAY BODIES*

The absorption and transverse strength of clay bodies, both in the fired and unfired state, are influenced greatly by the nature of the exchangeable bases present on the surface of the clay particles. Plastic clays with high exchange capacity are more affected than nonplastic clays, such as flint clays. Of the various common base forms studied, sodium-type clays in general require less water to give the same degree of stiffness, and their fired and unfired transverse strengths are high. Hydrogen clays require higher water content and have greater porosity and lower transverse strength. Data are given on a plastic fire clay, a ball clay, a bentonite, and two flint fire clays. All experiments made were on stiff-mud bodies.