SUBSTITUTION OF TOPAZ,DOMESTIC KYANITE,AND SYNTHETIC MULLITE-CORUNDUM FOR INDIA KYANITE: IV,RAW TOPAZ AS HIGH-TEMPERATURE BOND FOR DOMESTIC KYANITE*

Raw topaz has been found to act as a high-temperature bond for both raw and calcined kyanite. It is thought that this bonding action is due in part to volatiles which emerge from the raw topaz between 1000° and 1200°C. Some of the topaz decomposition products are absorbed and retained by the calcined kyanite. Within the limits of this investigation, all refractories which contained either calcined or raw kyanite, or mixtures of the two, with a minimum of 10% raw topaz had a good structure and were well bonded. The results of the load tests indicated that increased firing temperatures in the preheat improved the load resistance, but excellent high-temperature resistance was obtained by preheating as low as 1300°C. in laboratory kilns.     

PHYSICAL PROPERTIES OF MASSIVE TOPAZ*

Tests on the deposit of massive topaz in Chesterfield County, South Carolina, show that the mineral has a P.C.E. of 40 and a low permanent expansion. Most of the fluorine and water are driven off between 850° and 900 ° C. The fluorine, however, carries off with it some of the iron and considerable silica. The physical properties of a fire-clay refractory in which different amounts of topaz are used to replace flint fire clay have also been investigated.     

METHOD FOR DETERMINING TENSILE PROPERTIES OF REFRACTORY MATERIALS AT ELEVATED TEMPERATURES*

Equipment for testing ceramic materials to temperatures of 2000°F. was developed, and a method was devised for evaluating the bending stresses introduced by the test equipment. With this equipment, the tensile strength, stress-to-rupture characteristics, and modulus of elasticity of a sillimanite refractory were investigated at the Cleveland Laboratory of the National Advisory Committee for Aeronautics. The tensile strength varied from a minimum of 8000 lb. per sq. in. at 500°F. to a maximum of 19,000 lb. per sq. in. at 1800°F. Heat-treating the tensile specimens for one half hour at 1800°F. increased the tensile strength 35% at room temperature and 70% at 500°F. No increase in strength was noted at or above 1400°F. The stress-to-rupture in 1000 hours at 1600°F. was 8500 lb. per sq. in. The modulus of elasticity at room temperature was 20.3 × 10⁶.     

PROPERTIES OF SANDSTONES AS A REFRACTORY MATERIAL*

Sandstories from Chungking were tested for their properties as a refractory material. Chemical, petrographical, rational, and sieve analyses were made; properties, such as porosity, refractoriness, specific gravity, thermal expansion, and resistance to spalling. were determined; and studies were made on changes in firing up to 1550°C. No inversion of the quartz grains in the rock into tridymite or cristohalite could be detected. The interstitial clay substances fused first, and the quartz grains then dissolved gradually into the glassy matrix on firing at high temperatures. Being free from mineralogical and structural changes, unusually low in thermal expansion and porosity, and good in spalling resistance after firing at high temperatures, sandstones are shown to be an excellent refractory if properly employed. Of the two kinds of rocks, the dense and the porous, the former was found much better in test for refractoriness under load. Prefiring of the material before lining in a furnace structure is desirable to eliminate the permanent expansion and to improve the resistance to spalling in the raw state.     

Mg取代Y对Y-Mg-Si-Al-O-N氧氮玻璃性质的影响

为了研究Y-Si-Al-O-N玻璃中阳离子的组成和配比对玻璃的热性能、机械性能和化学稳定性的影响,通过Mg取代Y-Si-Al-O-N玻璃中的部分Y,制备了Y-Mg-Si-Al-O-N玻璃样品.用X射线衍射仪、差示扫描量热仪、金相显微镜和红外吸收光谱仪对样品进行了分析.结果表明:与Y-Si-Al-O-N氧氮玻璃相比,Y-Mg-Si-Al-O-N氧氮玻璃的玻璃化温度和抗20%HF腐蚀能力均急剧降低,显微硬度和抗弯强度则明显增强;Y-Mg-Si-Al-O-N删玻璃开始析晶的温度大大降低,析晶温度范围明显变宽,析晶能力明显增强.     

REVIEW OF FOUR YEARS OF RESEARCH ON REFRACTORY PROPERTIES OF PACIFIC NORTHWEST OLIVINE*

This discussion covers a study of the refractory properties of the olivine from two large deposits in Washington. The research was devoted mainly to (a) physical, chemical, and mineralogical properties, (b) effect of chemical additions, (c) development of the densest and most refractory body, (d) manufacture of brick, (e) comparison of these brick in P.C.E., spalling, load test, absorption, and resistance to basic slags with other brick, and (f) local use of olivine as a foundry sand.     

EFFECTS OF LITHIA SUBSTITUTION FOR SODA IN VITREOUS ENAMEL*

Lithia, as lithium carbonate, was substituted progressively for soda in the composition of a white cover frit. Substitutions were made on both weight and mol bases. Mol replacement of soda by lithia has resulted in improved fusibility, gloss, and opacity; higher gouge, surface abrasion, and acid resistance; and lower thermal expansion coefficient. Weight replacement has caused increased fusibility and gloss; a small decrease in surface abrasion resistance; marked decreases in opacity and in gouge and acid resistance; little change in thermal expansion coefficient, and a noticeable lowering of the transformation temperature.     

SURVEY OF LITERATURE ON SLAG TESTS FOR REFRACTORY MATERIALS*

A survey of the literature for the period 1932 through 1940 on the subject of slag tests for refractory materials is presented. This survey supplements similar reviews of Ferguson and of Simpson. A classified index to methods of testing and means for evaluating slag attack on refractories is also presented. This key has been prepared from references which appear in the present survey and also in the two previous articles. All of the references cited are to be found in the appended Bibliography.     

NATURE OF GEORGIA KAOLIN: I,EVIDENCE OF CHEMICAL AND COLLOIDAL ANALYSIS*

Samples of Georgia kaolins were investigated by thermal analysis and by X-ray and microscopic examinations. Soft kaolins were found to have a high percentage of crystalline kaolinite, whereas hard kaolins contained substantial amounts of less crystal lized material. Variations in the degree of crystallization, grain size, nature and amount of organic matter, and admixture of different minerals are given as reasons for the differences in the clays examined.     

APPARATUS AND METHOD FOR THE DETERMINATION OF POROSITY IN REFRACTORY MATERIALS *

The construction and operation of a mercury volumeter suitable for determining the volume of a composite sample of refractory grains is described. Porosity determinations by the method described are accurate within ∼0.15%. Convenient volume-density-porosity conversion charts are included.     

La置换Pb对Sb掺杂PZT压电陶瓷介电和压电性能的影响

研究了Pb1–xLax(Zr1–yTiy)1–x/4O3+1.5%(质量分数)Sb2O5陶瓷(PLSZT)的介电、压电性能及其微观结构,获得了高压电性能、小晶粒尺寸的压电陶瓷材料。结果显示:x≤5%时,晶体结构为纯钙钛矿相;x>5%时,为钙钛矿和焦绿石两相混和物。随着x的增大,介电常数和压电常数均呈现先增大后减小的趋势。介电常数在x=6%、y=0.45时最大,最大介电常数εmax≈3900,介电损耗tgδ≈1.8%;压电性能在x=4%、y=0.45时最强,压电应变常数d33≈600pC/N,径向机电耦合系数kp≈0.7,厚度机电耦合系数kt≈0.51,此时的平均晶粒尺寸约为2μm。     

PROPERTIES OF ENAMEL SLIPS: I,GENERAL PROPERTIES OF CLAYS AND ENAMEL SLIPS*

Five clays used to suspend porcelain enamels and their properties were studied. Fundamental data were first obtained on the clays, which were then milled in different proportions with several types of porcelain enamel frits. The properties of the resulting slips were studied. The pickup weight, that is, the amount of enamel retained on a ground-coated plaque which had been dipped in the slip and allowed to drain, was used as a basis of comparison.     

EFFECT OF SUBSTITUTING MgO FOR CaO ON PROPERTIES OF TYPICAL SODA-LIME GLASSES*

In base glasses containing (a) Na₂O 16, CaO 10, and SiO₂ 74% and (b) Na₂O14, CaO 12, and SiO₂ 74%, MgO was substituted in steps of 2% for CaO. The effects of the substitution on liquidus temperature, viscosity, fiber softening point, and the resistance of the glasses to dilute acid and to distilled water are described.     

风电叶片用国产碳纤维预浸料工艺性能和力学性能研究

应用碳纤维制备风电叶片结构件是大型风电叶片制作技术的一个发展方向。为推动国产碳纤维的发展应用,给出了风电叶片对碳纤维预浸料的技术要求,研究了国产碳纤维预浸料和进口碳纤维预浸料的力学性能和工艺性能,通过对比分析发现,面密度低的国产碳纤维预浸料力学性能高于进口碳纤维预浸料,但面密度≥600g/m2的国内碳纤维预浸料的工艺性能较差,需要进一步改进。     

FACTORS CAUSING THE VARIATION OF RESULTS IN TESTS FOR THE PHYSICAL PROPERTIES OF ENAMELS*

The reason for variability of tests for physical properties of porcelain enamel was investigated. Slight differences in gage of base metal, its source and method of manufacture, and the fineness and thickness of the enamel coating and firing temperature all seriously affect the results obtained. These physical properties may be adjusted at will by regulating the method of preparation.     

PROPERTIES OF ENAMEL SLIPS: II,SOLUBLE SALTS IN ENAMEL SLIPS*

This paper contains data on the soluble salts to be found in mill liquors obtained on milling a number of different commercial porcelain-enamel frits. The change in soluble salts on aging the enamel slips and the variation in pickup was also investigated. The mill liquors were found to contain chiefly Na₂O, B₂O₃, and NaF. The effect of various proportions of these salts was studied by adding NaOH, Na₂B₄O₇. 10H₂O, and NaF to a slip composed of clay, water, and fine-ground quartz. The correlation of the various data is discussed     

FUNDAMENTAL STUDY OF CLAY: VII,EFFECT OF PARTICLE SIZE ON PROPERTIES OF CASTING SLIPS*

Binary and ternary mixtures were made of 0.2- to 0.4-μ and 0.8- to 1.6-μ size purified fractions of clay and of 16- to 44-μ size purified flint. Specific gravity, deflocculation point, and hydrogen-ion concentration determinations were made on each composition to obtain the same apparent viscosity. Small cylinders were prepared by solid casting, and the shrinkage, porosity, and modulus of rupture of the dried specimens were measured. The general conclusions are as follows: (1) The packing of particles and the ratio of the plastic to the nonplastic components affect all slip properties; (2) the best combination of properties for casting slips was obtained at the composition corresponding to the closest packed system; (3) the casting time and drying shrinkage, both very small for bodies containing 20 to 25% of clay, increase together with the fine component; (4) the porosity of the dried casts is greatly affected by the particle-size distribution of the batch; (5) the minimum porosity of 28.5% obtained in this work is much lower than that of the standard sanitary body, which has a porosity of 35.5%; and (6) the particle-size control of casting slips not only will provide uniformity of the products but will also permit the desired variations in the properties of casting slips and cast bodies.     

多型体SiAlON(12H,21R)结合刚玉耐火材料的制备及力学性能

以电熔白刚玉、矾土细粉、铝(Al)粉和硅(Si)粉为原料,通过原位氮化反应烧结工艺在较低温度(1 500 ℃)下制备了多型体SiAlON[12H(SiAl5O2N5),21R(SiAl6O2N6)]结合刚玉耐火材料.研究了多型体SiAlON含量对材料的体积密度、显气孔率、常温及高温抗折强度的影响.用X射线衍射和扫描电镜分析材料的物相组成及显微结构.结果表明:随多型体SiAlON含量的增加,材料的常温及高温抗折强度显著提高,多型体SiAlON的质量分数为15%时,1 400 ℃材料的抗折强度可达29MPa.显微结构的研究表明:多型体SiAlON(12H,21R结合刚玉耐火材料的高温断裂方式以穿晶断裂为主.     

CASTING CHARACTERISTICS OF CLAYS: I,IMPROVED METHODS FOR DETERMINATION*

Part I of this investigation covers the development of reliable laboratory tests to indicate the relative properties of different clays with the primary consideration of their casting behavior. Methods are given for the determination of casting rate, permeability, water retention, fluidity, thixotropy, organic content, shrinkage, and dry strength. By determining the effect of varying increments of electrolyte on the foregoing properties, it is possible to select clays which have desirable casting characteristics for commercial use. Samples of fast- and slow-casting kaolins and ball clays were used to indicate the utility of the methods employed; results are also given for two composite bodies. In developing the test procedures using the Büchner funnel (vacuum), the effect of the following factors was determined: mixing procedure, ratio of clay to flint, feldspar vs. flint as the nonplastic, electrolyte content, quantity of slip used, specific gravity of slip, slip temperature, aging, and vacuum pressure; The optimum procedure for testing clays was then evolved. Part II and Part III of this series of studies are in preparation for publication.