景洪水电站混凝土变形性能及热学性能研究

大坝混凝土的绝热温升、导温系数、导热系数和比热等热学性能参数,是大坝进行温控设计必须的关键参数,对保证工程质量,节约工程投资具有重要意义。通过对景洪电站混凝土热学性能进行试验研究,提供可靠的变形性能及热学性能试验资料,以保证工程质量。

观音岩电站右岸大坝碾压混凝土配合比优化设计

云南观音岩水电站碾压混凝土大坝施工前,为了保证混凝土质量,在选定水泥、粉煤灰、外加剂和骨料等材料的基础上,进行了配合比试验。主要试验内容包括:最佳砂率、骨料级配、外加剂掺量、VC值以及混凝土极限拉伸值、抗冻抗渗性能、线膨胀系数、自生体积、比热、导热系数、绝对温升等。根据试验结果,最终选定了大坝碾压混凝土配合比。实际施工效果表明,混凝土砂浆骨料包裹均匀,泛浆良好,抗冻、抗渗、温升等指标均满足设计要求。

Passivity Degradation of Nuclear Materials in Reduced Sulfur Environments:A Review

This paper reviews sulfur-induced passivity degradation of nuclear materials with emphasis on steam generator(SG)alloys. The state of arts on this topic concerning thermodynamic calculation and experimental data has been reviewed. Thermodynamic calculation results indicate that the distribution of sulfur species strongly depends on p H and temperature. Experimental data show that solution p H, temperature and solution chemistries can significantly affect the electrochemical behaviors of SG materials and the underlying degradation mechanisms. Some issues when conducting corrosion tests at high temperature should be paid attention to, such as the dissolution of the autoclave, which may affect the facticity of the experimental results.

Deformation Behavior of Hot Isostatic Pressing FGH96 Superalloy

The deformation behavior of hot isostatic pressing （HIP） FGH96 superalloy was characterized in the temperature range of 1000-1100 ℃ and strain rate range of 0. 001-0. 1 s^-1 using hot compression testing. The flow curves of HIP FGH96, superalloy during hot deformation was analyzed systematically. The results show that deformation temperature, strain rate and strain are the main influence factors on flow stress of HIP FGH96 superalloy during hot deformation. The flow stress displays a peak at a critical strain and then decreases with further increase in strain. For a given strain, the flow stress decreases with the increase of deformation temperature, and increases with the increase of strain rate. A mathematical model of these flow curves was established through regression analysis and taking the strain as a modification factor. The calculated stress values agree well with the experimental values.

Development and Lubricating Properties of Rolling Oil for Stainless Steel Cold Rolling

Appropriate base oils and homologous additives such as extreme pressure and anti-wear agents,oiliness agents and antioxidants were selected,and experiments testing the compatibility performance between additive,base oil and other components were carried out to develop the SK and SD series of rolling oils for cold rolling of stainless steel.The developed oils were used in the stainless steel cold rolling lubrication experiments,and were successfully applied in the actual cold rolling operation of stainless steel.Compared with a foreign product,the tribological properties,the thermal oxidation stability,and the rolling lubrication performance of the developed stainless steel cold rolling oils were studied.Test results showed that the tribological properties of the thereby developed rolling oils and the reference one were almost at the same level,and to some extent the performance of rolling was even better than the foreign product,at the same time the stainless steel sheet could retain its well annealed performance.Meanwhile,within a certain range,the lubrication of the rolling oil became better as its viscosity increased at the same level of saponification value,which could provide a lower friction coefficient,so that a higher maximum reduction ratio of the rolled piece through a constant roll gap and a minimum thickness could be secured.Also,similar phenomena appeared as the saponification value increased at a same viscosity level of the rolling oils.

Effect of loading rates on the characteristics of thermal damage for mudstone under different temperatures

The uniaxial compression tests for mudstone specimens are carried out with four different loading rates from room temperature to 400℃ by using the Rock Mechanics Servo-controlled Testing System MTS810 and high temperature furnace MTS652.02.The mechanical properties of mudstone with various loading rates are studied under different temperature conditions.The results show that when temperature increases from room temperature to 400℃ and loading rate is less than 0.03 mm/s,the peak strength of mudstone specimen decreases as loading rate increases,while the various peak strengths show significant differences when loading rate exceeds 0.03 mm/s.At room temperature,the elastic modulus decreases at the first time and then increases with loading rate rising.When the temperature is between200 and 400℃,the elastic modulus presents a decreasing trend with increasing loading rate.With increasing the loading rate,the number of fragments in mudstone becomes larger and even the powder is observed in mudstone with higher loading rate.Under high loading rate,the failure mode of mudstone specimens under different temperatures is mainly conical damage.

Experimental Study on Flow Boiling of Deionized Water in a Horizontal Long Small Channel

In this paper,an experimental investigation on the flow boiling heat transfer in a horizontal long mini-channel was carried out. The mini-channel was with 2 mm wide and 1 mm deep and 900 mm long. The material of the mini-channel was stainless. The working fluid was deionized water. The experiments were conducted with the conditions of inlet pressure in the range of 0.2~0.5 MPa, mass flux in the range of 196.57-548.96 kg/m2 s, and the outlet vapor quality in the range of 0.2 to 1. The heat flux was in the range of 292.86 kW/m2 to 788.48 kW/m2,respectively. The influences of mass flux and heat flux were studied. At a certain mass flow rate, the local heat transfer coefficient increased with the increase of the heat flux. If dry-out occurred in the mini-channel, the heat transfer coefficient decreased. At the same heat flux, the local heat transfer coefficient would depend on the mass flux. It would increase with the mass flux in a certain range,and then decrease if the mass flux was beyond this range. Experimental data were compared with the results of previous studies. Flow visualization and measurements were conducted to identify flow regime transitions. Results showed that there were eight different kinds of flow patterns occurring during the flow boiling. It was found that flow pattern had a significant effect on heat transfer.