氧化物阳极材料在深井阳极地床中的应用

文章对金属氧化物阳极材料、使用金属氧化物为阳极的深井阳极地床的结构及特点进行了简要介绍，通过仪器参数、保护电位等数据，与传统的铸铁阳极地床进行对比，说明了金属氧化物阳极地床的特点。     

高土壤电阻率环境下的辅助阳极地床方式的选择

本文主要介绍了针对高土壤电阻率环境下阴极保护系统在辅助阳极地床的设计方式上的选择,深井阳极地床与浅埋阳极地床各有优缺点,也有需要综合使用的地方,有时候将深井阳极地床与浅埋阳极地床结合使用,会有意想不到的效果。     

平圩发电厂厂区深井阳极阴极保护系统检测评估与技术改造方案设计

1986年,平圩电厂首台600 MW机组安装的同时,采用深井阳极法对厂区管网和接地系统实施区域性阴极保护,运行18年后陆续失效和停运。为此组织了阴极保护检测评估,对石墨阳极深井阳极地床和户外型硒整流器恒电位仪进行全面检测和失效分析。技术改造方案采用WuZi新型深井阳极阴极保护系统技术,并作出工程设计。在电力行业推广应用新型深井阳极区域性阴极保护方面起到示范作用。     

新型深井阳极应用技术

为克服深井阳极运行中产生的气阻缺隙,一种贵金属氧化物(MMO)、免维修的新型深井阳极已成功应用于多个工程。以实例的方式介绍此类深井阳极的设计、安装过程以及在某供气管线上的运行情况。此新型深井结构合理,克服了“气阻”的危害,地表土壤电阻低,沿线电位降幅小且均匀,保护效果好。     

深井阳极地床设计和施工中的关键问题

用不等距法测某场站深井阳极地床处土壤电阻率沿垂直方向的分布,探讨了比较经济的阳极井深度,提出了在深井阳极地床安装过程中需要严格控制的关键环节。结果表明:土壤电阻率随地层深度的增大呈先减小后增大的趋势,比较经济的井深为40m;严格控制深井阳极地床施工中的关键环节,深井阳极地床的施工质量和阴极保护效果才能得到可靠保证。     

基于深井阳极阴极保护技术的储罐等级研究

针对以往深井阳极对储罐底板阴极保护数值模拟中存在的缺陷:金属构件极化曲线试验限定条件不同导致电位计算系统误差;没有考虑计算区域环境介质的不连续性,本文提出一种根据典型电流密度分布假设求解保护电位的方法:计算区域由土壤和沥青砂基础构成,根据阴极保护体系物理模型近似计算深井阳极极化电位。数值结果与现场实测电位数据对比验证了数值方法的可靠性,研究了单支深井阳极完全有效保护的临界储罐直径(等于56米)。     

分布式浅埋阳极在站场区域阴极保护中的应用

通过瞬间断电法对不同形式阳极地床保护下的站场及干线管道的电位进行测试,研究了不同分布形式的阳极地床对区域阴极保护效果及干线管道干扰的影响。结果表明：在埋地金属结构物密集区域,由于接地网的屏蔽作用,采用深井阳极地床难以使该区域的被保护管道达到有效的阴极保护;将分布式浅埋阳极埋设在被保护管道附近,阴保电流可通过较短的路径到达被保护管道表面,使被保护管道得到有效的阴极保护;深井阳极地床电流分布范围广,极易从干线管道远离站场的位置流入管道,然后通过站场绝缘接头外侧流入站内,会造成绝缘接头外侧电位偏正,形成阴极干扰;分布式浅埋阳极和柔性阳极对干线管道造成的干扰较小。     

深井阳极技术在城市大口径供水旧管线阴极保护中的应用

天津市自来水集团对两条已运行20年的大口径水源管道补加了阴极保护，采用了深井阳极技术，阳极井深达120m，解决了气阻和干扰问题，全线达到保护电位，延长了管道的使用寿命，节约了大量资金。本文介绍了此类型管道的保护电流密度选取、深井阳极形式，绝缘处理方式及干扰解决办法。     

深井阳极地床设计的实例分析

强制电流阴保系统是油气站场内埋地管道防腐蚀系统的重要组成部分.以山东某输气站场内区域阴保系统深井阳极地床的设计过程为例,首次将CDEGS软件应用到阳极接地电阻和地表电位梯度的计算过程中,旨在为以后深井阳极地床的设计提供借鉴.     

沙漠地区长输管道阴极保护设计

我国西部沙漠、戈壁地区建设了大量的天然气长输管道,由于西部地区尤其是沙漠地区土壤电阻率普遍较高,且地下水位埋藏较深,一般的牺牲阳极或强制电流浅埋辅助阳极不能满足阴极保护的技术要求,因此,深井阳极在该地区的应用日渐深入和广泛。文章介绍了内蒙古鄂尔多斯地区长距离输气管道采用新型深井阳极阴极保护技术的情况。     

院校研究的基本范式:定性模式与定量模式

院校研究有两种研究路向,一种是“(问题)一理论—假设—观察一理论一(问题)”的研究路径,另一种是“(问题)一观察一概括一理论—观察一(问题)”的研究路径。从哲学方法论层面看,院校研究主要有四种研究范式,即经验主义、实证主义、结构主义和人本主义。其中,实证主义和经验主义是定量研究的方法论基础,结构主义与人本主义是定性研究的方法论基础。定性研究与定量研究并不是绝对的两分,它们构成一个连续的系谱。实验法与文学法位于这一系谱的两个极端。     

GMAW焊接熔滴过渡动态过程的数值分析

以流体动力学、电磁理论及VOF方法为基础建立了熔滴过渡的动态模拟模型，模型中考虑电磁收缩力、表面张力、等离子流力的影响．利用建立的模型模拟了熔滴的形成、长大及脱离过程，计算了电流对过渡熔滴尺寸及频率的影响，计算结果与实验结果吻合较好．计算了不同阶段的熔滴中的流场，并利用计算的流场分析了熔滴的脱离机制。     

An ab initio study of Ti-Y-O nanocluster energetics in nanostructured ferritic alloys

So-called oxide dispersion strengthened steels or nanostructured ferritic alloys (NFAs) contain nanoprecipitates which give them exceptional mechanical properties and resistance to radiation effects. However, the structure and composition of these nanoprecipitates are still uncertain. To help clarify the nature of the smallest nanoprecipitates, density functional theory calculations are used to investigate the most stable Ti, Y, and O nanocluster computational units in Fe. Two distinct methods for searching for stable nanoclusters are proposed: one in which nanoclusters are restricted to the body-centered cubic Fe lattice and one in which the nanocluster structures are strained variants of bulk Ti and Y oxides. We discovered that nanoclusters that are structurally similar to bulk Ti and Y oxides are significantly more stable than nanoclusters that are restricted to the Fe lattice. Consequently, the most stable nanoprecipitates in Ti-Y-O NFAs are more likely to be small oxide phases than coherent solute-enriched clusters.     

“我国古代大型铸铜文物”系列文章之十三：古代大铜锅和大铜缸（待续）

叙述了古代大铜锅和大铜缸的有关情况。在现存的26口古代大铜锅中,重点介绍了其中6口大铜锅的尺寸、铸造年代、功用、特点和存放地。而现存的165口古代大铜缸,都是明、清两代铸造的,绝大多数都存于北京故宫,本文较详细地介绍了其中5口大铜缸的有关情况。     

Rupture locations of friction stir welded joints of AA2017-T351 and AA6061-T6 aluminum alloys

The tensile rupture locations of friction stir welded joints of AA2017-T351 and AA6061-T6 aluminum alloys were examined. The experiments show that the rupture locations of the joints are different for the two aluminum alloys, which are influenced by the welding parameters. When the joints are free of welding defects, the AA2017-T351 joints are ruptured in the weld nugget adjacent to the thermo-mechanically affected zone on the advancing side and the rupture surfaces appear as oval contours of the weld nugget, while the AA6061-T6 joints are ruptured in the heat affected zone on the retreating side and the rupture surfaces are inclined at a certain degree to the bottom surfaces of the joints. When welding defects are present in the joints, the AA2017-T351 joints are ruptured in the weld center, while the AA6061-T6 joints are ruptured on the retreating side near the weld center. The rupture locations of the joints are dependent on the internal structures of the joints and can be explained through them.     

2219铝合金不同气氛下TIG焊焊接接头组织性能

为研究氦弧TIG焊焊缝质量,对比分析了2219铝合金氦弧TIG焊与氩弧TIG焊焊缝成形及组织性能.结果表明,在背部熔宽相同的条件下,氦弧TIG焊焊缝正面熔宽、下塌量及热影响区宽度均小于氩弧TIG焊,氦弧TIG焊与氩弧TIG焊焊缝的微观组织及第二相组织基本相似,焊缝区晶粒为等轴晶,热影响区晶粒为粗大的板条状,组织为粗大的α铝基体与金属间化合物Al₂Cu及少量的共晶组织,焊缝区的第二相组织明显多于热影响区,无法发挥弥散强化的作用.氦弧TIG焊与氩弧TIG焊焊接接头的断裂方式均为韧性断裂,抗拉强度基本保持一致,氦弧TIG焊焊接接头的断裂总延伸率高于氩弧TIG焊,维氏硬度高于氩弧TIG焊焊缝的硬度.     

机械合金化的反应机制研究进展

介绍了机械合金化技术的基本原理、工艺过程及特点，对目前机械合金化存在的两种机制进行了分析，指出通过原子扩散逐渐实现合金化反应机制和爆炸式反应机制实质上是相似的，导致效果的不同主要在于合金体系的形成热不同。另外对影响机械合金化过程的因素以及该工艺存在的缺陷进行了阐述。     

A force model for nose radius worn tools with a chamfered main cutting edge

The three-dimensional cutting forces for nose radius tools with a chamfered main cutting edge incorporated with a tool-worn factor are presented in this paper. The variations in shear plane areas occurring in the tool-worn situation are used. The results obtained from the proposed model shows good agreement with the experimental data on both chip formation as well as cutting forces. In the experimental work the throwaway tips are locked onto the pocket of the tool holder. The holders for special tools are designed first. Next, the tool holders are manufactured by using medium carbon-steel bars and the mounting tips are designed based on various specifications. Finally, the nose radius tips mounting in the tool holder are ground to a wear depth, and the worn tool dimensions are measured by using a profile projector. The shear area and the friction area are calculated accordingly. Then the three-dimensional cutting forces will be obtained from those data.     

Characterization of nanostructured TiN coatings fabricated by reactive plasma spraying

The nanostructured TiN coatings are fabricated by means of reactive plasma spraying micrometers titanium powders in the atmosphere, and the microstructure and performance of the coatings are analyzed by XRD, SEM and TEM. The experimental results show that the coatings are mainly composed of TiN and Ti₃O phases, and the coatings have the typical sprayed lamellae structures. In parallel to substrate surface direction, the nanoscale grains with particle diameters ranging from 60 to 120nm are observed in the coatings, and both fine equiaxed and columnar grains are found in some zones of the nanostructured TiN coatings. But in vertical to substrate surface direction, the contrary is the case. Thus it can be concluded that the TiN coatings are composed of the columnar grains, and the columnar grains are nanostructural equiaxed grains in their cross-section. In addition, a large number of deformation twins caused by the stresses concentration are found in TiN coatings. Meanwhile, the nanostructured TiN coatings have a higher bonding strength and better fracture toughness than other observed as-sprayed coatings.     

凝固过程中电流作用机制评述

综述了当前国内外有关电流在金属凝固过程中作用的研究状况,从理论上归纳和分析了电流对凝固过程产生作用的主要机制,对现有理论及计算公式进行推导,对相应公式进行进一步补充,对电流在凝固过程中的应用和进一步研究进行了展望.