净水厂两种典型滤池设计应用解析

V型滤池和翻板型滤池是目前水厂净水工艺中两种技术较为先进的滤池,通过对这两种滤池的工艺过程、工艺特点、主要设计参数、自动化控制等方面进行比较分析了两种滤池各自的优缺点及适用范围。     

真空熔炼参数对MCrAlY合金及粉末中Y残余含量的影响研究

本文通过真空熔炼和真空雾化工艺制备了MCr Al Y合金铸锭及粉末,研究了真空熔炼过程中保护气压力和保温时间对MCr Al Y合金铸锭中Y的收得率的影响以及上述两种工艺在不同Y配入量下Y的残余含量的变化。结果表明,真空熔炼过程中Y的收得率随保护气体压力和保温时间的增加而减小;Y在真空雾化工艺的雾化过程中损失较小,两种工艺在相同的Y配入量下具有接近的Y残余含量。     

回转窑托轮铸造工艺优化

本文介绍托轮的工况条件、技术要求,及其结构设计的改进和主要缺陷:剥落失效。介绍两种主要托轮铸造工艺及其特点,通过凝固过程数值模拟,进一步分析了两种主要工艺的优缺点。铁芯工艺生产的铸件质量可靠,操作方便,工期较短,成本也较低。     

铜阳极泥氧气斜吹旋转转炉工艺分析与优化

详细分析了某厂铜阳极泥氧气斜吹旋转转炉工艺过程及存在的问题。针对氧气斜吹旋转转炉工艺过程中硒回收率偏低、环保布袋糊袋严重及两级动力波除尘差的问题,结合炉窑在实际生产过程中的工艺情况,优化设计了一种新型旋转式加料装置,并将除尘、吸收为一体的两级动力波工艺改为“高温滤袋柔性膜收尘+高效吸收装置吸收工艺”。通过对加料装置和两级动力波工艺的优化,解决了非加料阶段的高温腐蚀料管的问题,使得原系统的液固分离同时取消,系统阻力、生产过程动力消耗大幅度降低。     

201×7WA两种树脂在仲钨酸铵试验中的研究

阐述了以白渣为原料试制仲钨酸铵的工艺过程.试验采用离子交换工艺,对两种不同的阴离子进行了对比试验分析,结果表明,210×7WA两种树脂,WA树脂饱和容量较大,是一种大孔型阴离子交换树脂,生产中对节省仲钨酸铵投资费用和降低单位产品成本具有一定意义.     

不锈钢中厚板HNO3+HF混酸酸洗工艺研究

对不锈钢中厚板HNO3+HF混酸酸洗和常规H2SO4+(HNO3+HF)酸洗工艺进行了实验室的对比分析,并对HNO3+HF混酸酸洗工艺在生产过程中进行了小批量试验。结合实验室和大生产的试验情况,对两种酸洗工艺,从酸洗质量、效率、成本、环保、可适合钢种等方面进行了对比分析,提出了两种酸洗工艺的优缺点。     

带与不带启动阀的TRT机组转速控制

针对当前TRT两种不同的典型工艺布置,对带与不带启动阀的两种TRT升速过程进行了比较,并分析了差异原因。针对转速控制,推荐带启动阀的TRT工艺布置。     

镗床深孔镗削的工艺分析

根据我厂深孔镗削加工的工艺特点,深孔镗削工艺可分为两大类:推镗法和拉镗法。现将这两种工艺特点分析比较如下。1 推镗法 推镗法在镗削过程中,镗杆始终处于轴向受压状态下进行工作。安排屑方式不同它可分为向前排屑推镗法和向后排屑推镗法两种。     

用渗析法回收锌电解废液中的H_2SO_4的研究

本文叙述了用渗析法回收锌电解废液中硫酸的工艺过程。本工艺采用离子交换膜,用单体渗析器测定了膜在两种不同电解液中的使用寿命。考察了Zn~(2+)、Mg~(2+)、及Cl~-在渗析过程中的行为。在试验室扩大试验中考察了影响渗析过程的主要因素,最后为工业生产推荐了两种可行的工艺流程。     

不同的钒渣提钒浸出方式的工艺条件及发展方向

讨论了钒渣提钒过程中分别适应于流化床和固定床两种浸出方式的不同工艺条件，并指出半汉化床与固定床相结合的工艺是浸出工艺的发展方向。     

Fabrication of fiber-reinforced metal-matrix composites by variable pressure infiltration

A model for variable pressure infiltration of fibrous preforms by molten metal has been developed. The mechanism of the infiltration and the effects of fiber distribution and wettability on infiltration resistance and composite microstructure have been studied. It is shown that the model is in good agreement with the experimental data on infiltration of carbon-fiber preforms by Al-Si eutectic. The solution of the resulting equation shows that the rate of infiltration is only a function of the rate of change of pressure Ф, by which the infiltration processing is controlled precisely. Two kinds of infiltration modes have been found. A critical fiber volume fractionV _c exists, which is the turning point of the infiltration modes as well as permeability. As fiber volume fraction exceedsV _c, the infiltration mode changes from nonuniform to uniform, resulting in a sharp decrease in permeability. The permeability and resistances of these two infiltration modes are well predicted by the variable pressure infiltration theory. If fibers are wetted by molten metal, the preforms can be completely infiltrated at low applied pressure. In the case of nonwetting, poor infiltration of the preforms up toV _cresults, though high pressure is applied, but quality composites are formed at a low applied pressure if the fibers in the bundles are fixed relative to each other. A novel process, variable pressure infiltration technique, has been generated, which offers the advantages of low applied pressure, easy control of the pro-cessing, and no requirement of wetting. Quality C/A356 composites have been fabricated by this technique with the investment precision casting molds at a pressure of 0.6 MPa. Also, the mechanical properties of the composites are studied. The composites have high strength with a special fracture mechanism.     

Simulation of metal-matrix composite isothermal infiltration processing

In pressure infiltration processing of metal-matrix composites, molten metal is injected under external pressure into a porous preform of the reinforcing phase and solidified, either during infiltration or after the mold is filled. If infiltration is isothermal, the physics of the process are similar to drainage phenomena encountered in soil mechanics. Using this similarity, a finite-element software is developed to simulate metal-matrix composite infiltration by adaptation of a code originally developed for soil mechanics. Solutions are given for isothermal infiltration of porous preforms by a molten metal under any increasing function of the applied pressure vs time, taking into account capillary phenomena. Experimental validation is performed using SAFFIL alumina fiber preforms infiltrated with an aluminum matrix in a series of isothermal infiltration experiments in unidirectional and axisymmetric configurations. Numerical and experimental data show good agreement, both in terms of infiltration kinetics and porosity distribution. The simulation tool can, thus, be applied for isothermal infiltration of complex geometries and boundary conditions and aid mold design and process parameter optimization.     

Pressureless infiltration of aluminum metal-matrix composites

Pressureless infiltration of ceramic preforms by molten aluminum is described. The preforms are SiC with varying amounts of particulate Al, Ti, and Ni. Infiltrants employed are pure Al and Al-12.5 wt pct Si. It is shown that a pressure differential within the preform is required for infiltration, and measurements are made of pressure changes in the preforms during infiltration. Results indicate that atmospheric pressure is essential for infiltration but that capillarity may play a role as well. T. NUKAMI, formerly Research Assistant, Massachusetts Institute of Technology     

Sizing Stormwater Infiltration Structures

A design aid is presented for sizing stormwater infiltration structures. The proposed procedure is based on the hydrological storage equation for an infiltration structure coupled with the Green and Ampt infiltration equation. For the filling process, the two equations are solved simultaneously using a numerical method, and the results are presented in chart form. These charts are useful to determine the maximum water depth in an infiltration structure. For the emptying process, the governing equations are integrated analytically resulting in an algebraic equation that can be solved for the emptying time explicitly. A practical application is included to demonstrate the ease of the suggested procedure.     

洁净燃料发动机粉末冶金阀座熔渗烧结工艺研究

采用正交试验优化了洁净燃料发动机粉末冶金阀座熔渗烧结工艺参数,分析了熔渗烧结工艺参数对阀座密度和上下面硬度等性能的影响。结果表明:随着渗铜量的增加,阀座材料密度迅速增加,上下表面硬度差距缩小。熔渗烧结温度对阀座材料密度影响不大。当熔渗烧结温度从1130℃升高到1165℃,材料硬度逐渐提高;当温度达到1200℃后,Co–Cr–Mo硬质颗粒中合金元素向基体中发生明显扩散,导致阀座硬度下降。熔渗烧结时间对材料密度影响不大,缩短时间有利于缩小上下面硬度差距。当渗铜质量分数达到20%,渗铜温度1165℃,渗铜时间40 min,阀座力学性能最佳。熔渗烧结后密度为8.15 g·cm~(-3),上下表面硬度分别为HRC 30.4和HRC 30.1,基体材料与Fe–Mo、Co–Cr–Mo硬质颗粒均有一定的冶金结合。     

Quick Method for Estimating Furrow Infiltration

This paper presents a simple and quick method for estimating furrow infiltration using a single advance point based on the volume balance equation. The furrow infiltration and water front advance along the furrow are assumed to follow the modified Kostiakov infiltration and power advance equations, respectively. The volume balance equation, including these equations, is simplified to a function containing two parameters, i.e., the exponents of power advance and Kostiakov infiltration equation (with a prior-known basic infiltration rate). These parameters are estimated by minimizing the function to zero using a quasi-Newton search algorithm, provided with Excel Solver. The estimated exponents are used to determine the Kostiakov infiltration parameters. The proposed one-point method is tested with seven independent furrow irrigation evaluation data sets and the estimated cumulative infiltration is compared with the observed counterparts. Performance of the proposed method was evaluated using the root-mean-square error and index of agreement (Ia). The results show that the proposed one-point method estimated cumulative infiltration is closer to the observed; the method performed as good as Valiantzas’ method. Shepard’s method did not perform well for the tested data sets. The algorithm and the results of the proposed method reveal that the proposed method can be used as a tool for quick estimation of furrow infiltration using a single advance point.     

Toward Physically Based Estimation of Surface Irrigation Infiltration

Irrigation practitioners use empirical infiltration equations. Theoretical infiltration equations are currently not capable of capturing surface irrigation infiltration behavior, particularly during initial wetting. For a coarse textured soil, an example is shown where the Green-Ampt equation can be adjusted to match field “average” infiltration conditions by altering the soil’s physical properties. For finer textured soils, a time offset is proposed for adjusting the Green-Ampt equation to account for cracking and soil consolidation upon wetting. This results in a nonzero infiltration amount at time 0, a phenomenon commonly observed for infiltration of cracking soils. Applying this concept to the Philip equation (same as Modified Kostiakov equation with a = 1/2) suggests the addition of an offset parameter. A modification to the two-point method is presented for this equation with the aim to better fit mathematical parameter functions to infiltration data.     

反应熔渗法制备C/C-SiC复合材料及其影响因素的研究进展

比较了C/C-SiC复合材料的3种主要制备方法,介绍了反应熔渗法制备工艺,以及液Si渗入C/C多孔体、液Si与固体C反应和C/C-SiC复合材料性能的主要影响因素,提出了尚待解决的关键问题。     

Design of Two-Layered Porous Landscaping Detention Basin

Under the mandate of the Federal Clean Water Act, porous landscaping detention (PLD) has been widely used to increase on-site infiltration. A PLD system consists of a surface storage basin and subsurface filtering layers. The major design parameters for a PLD system are the infiltration rate on the land surface and the seepage rate through the subsurface medium. A low infiltration rate leads to a sizable storage basin while a high infiltration rate results in standing water if the subsurface seepage does not sustain the surface loading. In this study, the design procedure of a PLD basin is revised to take both detention flow hydrology and seepage flow hydraulics into consideration. The design procedure begins with the basin sizing according to the on-site water quality control volume. The ratio of design infiltration rate to sand-mix hydraulic conductivity is the key factor to select the thickness of sand-mix layer underneath a porous bed. The total filtering thickness for both sand-mix and gravel layers is found to be related to the drain time and infiltration rate. The recommended sand-mix and granite gravel layers underneath a PLD basin are reproduced in the laboratory for infiltration tests. The empirical decay curve for sand-mix infiltration rate was derived from the laboratory data and then used to maximize the hydraulic efficiency through the subsurface filtering layers. In this study, it is recommended that a PLD system be designed with the optimal performance to consume the hydraulic head available and then evaluated using the prolonged drain time for potential standing water problems under various clogging conditions.     

熔渗量对颗粒增强的高性能铁基耐磨材料性能影响的研究

为研制在某些特殊工况条件下用的高强度、高耐磨性的铁基耐磨材料，采用烧结一熔渗一热处理工艺研制出一种由Co—Cr—Mo—Si颗粒增强的铁基粉末冶金耐磨材料。结果表明：Co—Cr—Mo—Si硬颗粒单独存在于基体中，起颗粒强化的作用。未熔渗时，孔洞多，硬颗粒与基体界面清晰可见，结合强度低，材料性能较差。随着熔渗量的增多，材料的孔隙度减小，硬颗粒与基体界面结合强度好，材料性能明显提高。同时，材料的断裂主要通过铜相的撕裂，呈现明显的塑性断裂特征。因此，足够的熔渗量可获得各相界面结合较好的一种高性能铁基材料。