Experimental study of NiO electrical conductivity changes under low oxygen pressures

The electrical conductivity of NiO was measured at 740°C in an oxygen pressure range of 10^–2 –1.3 Torr. By means of continuous recording, longtime experiments were performed. The results show that for any admittance of oxygen, the electrical conductivity initially increased and then decreased to its initial value. For pressures higher than 0.1 Torr the decrease of the signal was reduced and the time required to attain the initial value sometimes reached several days. These results suggest that the electrical conductivity changes may be considered as a transitory phenomenon connected to attaining gassolid equilibrium.     

Nd—Pd—Ru三元系富钯区域的相图

用Ｘ射线衍射和金相显微镜分析方法研究了Ｎｄ－Ｐｄ－Ｒｕ三元系的富钯区域，作出部分相图的７００℃等温截面。发现Ｒｕ在（ＮｄＰｄ３）中有高达１３ａｔ％的固溶度。该截面上存在４个单相区：（Ｐｄ），（Ｒｕ），ＮｄＰｄ５和ＮｄＰｄ３；５个二相区：（Ｐｄ）＋（Ｒｕ），（Ｐｄ）＋ＮｄＰｄ５，ＮｄＰｄ５＋ＮｄＰｄ３，ＮｄＰｄ３＋（Ｒｕ）和ＮｄＰｄ５＋（Ｒｕ）；２个三相区：（Ｒｕ）＋ＮｄＰｄ３＋ＮｄＰｄ５和（Ｐｄ）＋（Ｒｕ）＋ＮｄＰｄ５。     

高强耐磨复杂铝黄铜研究

在生产HA164-5-4-2过程中，解决了Fe、Mn的熔化及均匀化、无缺陷铸锭的生产方法、管材直度控制等工艺关键问题。合金的熔点910、4℃，流点949．2℃，相变热焓114．6J／g；热加工性能优良；在高于550℃时其组织是β相，在低于550℃时其组织是α β相，耐磨颗粒是多元富铁相；力学性能分别为σb=796MPa，σ0.2=675MPa，δ5=20％，IIB=218。同时报道了不同热处理条件下组织和性能的关系。     

A computational study of austenite formation kinetics in rapidly heated steels

Surface hardening of steels involves rapid austenitization and subsequent quenching of the surface. The resulting extent of hardening largely depends on the rate of austenitization of the surface under the applied high heating rates. In the present work the kinetics of austenite formation in Fe-C alloys during rapid, non-isothermal heating conditions, characterized by high heating rates and short austenitization periods, were studied by means of computational simulation. Austenitization of lamellar pearlite/proeutectoid ferrite microstructures was simulated by assuming two kinetically distinct stages: i) dissolution of lamellar pearlite followed by ii) dissolution of proeutectoid ferrite. The two stages were simulated by two corresponding 1-D diffusion models employed in series. Numerical solution of the resultant moving-boundary diffusion problems provide calculated results regarding the dependency of vol. fraction austenite on thermal cycle parameters and on initial microstructural features of the steel. Analysis of calculated results showed that the vol. fraction of pearlite transforming to austenite during pearlite dissolution depended on maximum temperature, dwell time and pearlite interlamellar spacing. A functional relationship between these variables, consisting of a thermodynamic and a kinetic term, was established. On the other hand, the total vol. fraction of austenite forming in the steel, after both stages of austenitization, was found to follow a typical sigmoidal kinetic behaviour.     

Grinding-hardening with liquid nitrogen: Mechanisms and technology

This paper studies an innovative development of a steel grinding–hardening technology using an inert cryogen—liquid nitrogen. It was found that phase transformations took place during grinding with the application of liquid nitrogen and resulted in hardened surface layer in a ground component. The layer had a fine laths martensite structure which gave rise to a remarkably high hardness. It was also shown that the treatment can produce superior surface integrity, with compressive surface residual stresses and without surface oxidation. Due to the inert nature of the liquid nitrogen, the grinding process becomes environmentally conscious.     

Laser-induced fluorescence (LIF) studies of liquid-liquid flows. Part I: Flow structures and phase inversion

A non-intrusive dye tracing technique, laser-induced fluorescence (LIF), has been applied to investigate the co-current flow of two immiscible organic-aqueous liquid flows in a vertical pipe. This technique allowed detailed visualization of the dynamic evolution of the flows. Flow structures in liquid-liquid flows at high dispersed phase fraction were revealed which had not been seen before. In pipe flow, an unstable range was found in the flow pattern map in which oil-in-water (o/w) and water-in-oil (w/o) dispersions could co-exist. Secondary dispersions (o/w/o and w/o/w) were observed for most volume fractions and velocities, especially in the unstable range. It was observed that, when the flow is in the unstable region, both w/o/w and o/w/o secondary dispersions could appear in the same set of experiments. It was found that this unstable range in the pipe flow, in spite of the similar appearance, was different to the ambivalent range seen in agitated systems. The one-dimensional drift flux model of Wallis (1969) for dispersed flow and a laminar model for co-current downward annular flow, were also applied to predict the in situ oil holdup; good agreement was obtained.     

Ozone Contactor Hydrodynamics

Tracer tests were conducted at the 6,000 pounds of ozone per day Tucson, CAP Water Treatment Plant in Tucson, Arizona. The tests were designed to determine T₁₀ values through the contactors at various operating conditions. The tests were modeled using three techniques. Peclet Number was calculated for each of the runs, which would indicate the hydrodynamic conditions inside the ozone contactor. The results indicated that the increase in water flow rate and the number of cells with gas flow increased Peclet Number. The flow rate of liquid seemed to impact the Peclet Number more than gas flow. The headloss in each cell appeared to be important in controlling the distribution of liquid and gas through the cell. A correlation was developed between the product of gas and liquid phase Reynolds Number and Peclet Number.     

Complex Phase Equilibria in Refractories Design and Use

The current applications of phase diagrams and thermodynamic calculations to studies of refractories are reviewed highlighting links to microstructural analyses. Improved understanding of microstructural evolution and chemical corrosion mechanisms has resulted from such work. The limitation of the calculations/diagrams to thermodynamic equilibria has led to imaginative attempts to incorporate some dynamic aspect in them so they are more relevant to practical conditions. These include varying temperature to model a temperature gradient, P _O2 to model atmosphere permeation into a brick, slag/refractory ratio to model slag penetration and altering the slag composition after reaction with the fine matrix phases. The potential future development of such techniques is discussed.     

Isobaric vapor—liquid equilibria for binary systems composed of methyl butanoate with ethanol and with propan-1-ol at 114.66 and 127.99 kpa

Vapor-liquid equilibrium data for the binary systems methyl butanoate/ethanol and methyl butanoate/propan-l-ol at pressures of 114.66 and 127.99 kPa are presented. Both mixtures yield an azeotrope, the compositions (ester) of which decrease quasi-linearly as the pressure increases. The experimental data for all the binary mixtures were fitted to a suitable equation and then used for comparison with predictions by ASOG and UNIFAC methods. These group contribution models give a good estimation of activity coefficients with an overall mean error less than 5% for all cases.     

结晶性高聚物作为相变材料的应用

本文研究了结晶性高聚物聚乙烯及其共混物作为相变材料对模拟发热体铜片热量的吸收作用，由于相变的吸热，铜片的温度在一定时间范围内保持在一个定值。选择不同的相变材料，可使这种温度平台出现在不同的温度范围，不共晶的共混物可有两个以上的温度平台，提高了降温效果。