一种海水缓蚀剂缓蚀行为的研究

利用电化学方法和表面分析测试技术，研究了有机膦酸醇酯类缓蚀剂(YKI-05)对于907A钢在天然海水中的缓蚀行为．实验表明，在静态海水中，浓度为300mg／L的YKI-05缓蚀剂能在907A钢表面形成稳定的缓蚀膜层，是一负催化阴极型缓蚀剂，在实验周期内其对907A钢的缓蚀效率较高；并用原子力显微镜(AFM)和俄歇电子能谱(AES)对该缓蚀膜的表面形貌和成分进行分析．     

药芯焊丝电弧焊电弧形态与熔滴过渡行为的研究

基于数码照相技术研究了CO2保护气氛下,渣系和焊接参数对药芯焊丝电弧焊（FCAW）电弧形态和熔滴过渡行为的影响。研究发现,酸性及金属芯渣系药芯焊丝在所有焊接参数下电弧扩散角相差不大,碱性渣系药芯焊丝因药芯中含大量消电离元素,大焊接参数下电弧扩散角比其它两种渣系小;金属芯药芯焊丝大焊接参数下发生“半潜弧”,可见弧长显著缩短。随着焊接参数增大,酸性,碱性,金属芯药芯焊丝均依次出现如下熔滴过渡类型;短路过渡、大滴排斥过渡、细颗粒过渡,均未发生喷射过渡。     

熔滴过渡小型光谱传感器

光谱信息是目前所发现的反映焊接熔滴过渡的最佳信息源，但是基于光谱仪的熔滴过渡信号检测系统不能用于在线实时控制。基于光谱信息检测思想，开发了小型实用的光谱传感器。章详细介绍了该熔滴过渡小型光谱传感器的设计思想和具体设计结构，并进行了理论探索，给出了小型光谱传感器的实际结构和在线应用情况。     

基于能量流和仿真的压铸机能耗建模与评估北大核心

针对压铸机能耗高、能量利用率低的问题,提出一种基于能量流和仿真的压铸机能耗模型,研究压铸机能耗特性与重要工艺参数对系统能耗的影响;针对压铸机能耗等级评估周期长、成本高的问题,提出一种基于能耗模型仿真测算压铸机能耗等级的新方法。分析压铸机的能量流特性,根据其能耗分布规律和能量守恒原理,构建压铸机能耗计算模型;采用AMESim与C语言联合仿真,建立压铸机液压系统能耗仿真模型,研究压铸机不同增压压力与不同快压射速度对系统能耗的影响;仿真得出压铸机能耗数据,并按相关标准评估压铸机的能效等级。研究结果显示合开模过程能效较高,有用功约占总能耗的50%;压射过程能效较低,有用功约占总能耗的21%,快速压射阶段瞬时功率非常高;增压压力与快速压射速度变化均对压射机构能耗影响较小;仿真测算出的压铸机能效等级与实测结果接近,比能耗误差为8%,显示提出模型与方法具有较好的准确性与可行性。     

定型模内塑料异型材冷却过程的数值模拟

定型模是挤出模具的重要组成部分,采用数值模拟方法研究定型模内塑料异型材的冷却过程,可以指导定型模冷却系统的设计。本文基于传热学基本原理,分析了定型模内型材冷却过程数值模拟的初始条件和边界条件,并利用大型有限元工程分析软件ANSYS完成了型材冷却过程的数值模拟,从而证明了数值模拟用以研究型材冷却过程的有效性。     

Research of novel oscillating wire feeding system using the AC servo motor

With the background of the control of additional mechanical force droplet transfer in MIG/MAG welding, regarding the AC servo motor as core, a novel oscillating wire feeding system has been developed with excellent performances of control and dynamic acceleration which is tested. System constitution and operation principle are introduced in this paper. Influences of parameters on dynamic acceleration performance are analyzed and discussed emphatically, such as oscillating frequency, oscillating amplitude and draw-back speed. Experimental result indicates that according to the technique of welding control, the novel wire feeding system responds rapidly to various kinds of control orders of wire feeding and draw-back, and realizes flexible control of welding wire axial movement, including dynamic shifting ,oscillating and so on.     

Laser melting of Ti-15Al-20Nb alloy

Titanium aluminides have become promising materials for high-temperature applications, but the relatively poor oxidation resistance and elevated- temperature strength of these alloys limit their application to temperatures lower than 1000 °C. Niobium addition improves the properties of titanium aluminide. However, the mechanical, metallurgical, and corrosion properties of Ti- Al- Nb may be improved by treatment with a laser beam. Consequently, the present study examines the properties of Ti- 15Al- 20Nb alloy subjected to the Nd:YAG laser melting process. Hardness in the surface region increases to twice the base material hardness, and corrosion resistance improves considerably after laser treatment.     

HEAT TRANSFER ANALYSIS DURING ROLLING OF THIN SLAB IN CSP

A mathematical model has been built to numerically predict the thermal history of thin slab during CSP （compact strip process） rolling. To estimate the temperature distribution in the slab mare accurately, the mathematical model combines heat transfer in the slab, in the roll, and at the roll-slab interface during bite. The numerical results agree with on-site running data, which proves the reliabili~, of the mathematical model. The results show that roll chilling has a significant effect on the temperature distribution in the slab.     

注射模CAE远程应用系统的研究与实现

研究了注射模CAE远程应用系统的实现方法。围绕建立最优系统模型 ,探讨了数据压缩算法和FTP文件服务 ,并采用主从服务器分离法提高系统性能。为进一步优化系统 ,运用了多线程、套接字、ADO和RAS远程拨号等技术。     

Sliding wear of non-hydrogenated diamond-like carbon coatings against magnesium

Magnesium alloys are of increasing interest to the automobile industry for their potential in reducing vehicle weight, and in turn, improving fuel economy and lowering emissions. It follows that improving the magnesium manufacturing processes will promote greater use of magnesium alloys in automobiles. In recent years, diamond-like carbon (DLC) coatings have attracted attention for their low coefficient of friction (COF) and wear rates. The implementation of DLC coatings on tool and die surfaces may help increase the efficiency of magnesium component manufacturing processes (such as cutting and sheet forming) and also improve the surface quality of the finished products.In this study, the dry sliding wear behaviour of magnetron sputtered non-hydrogenated DLC coatings against Mg (> 99.9 wt.%) was investigated using a vacuum pin-on-disc tribometer. Tests were performed in ambient air (28% RH) and in argon, under a constant load of 5 N and at a sliding speed of 0.12 m/s. In argon, the non-hydrogenated DLC coatings showed a very low COF of 0.05 after an initial running-in period. Carbonaceous material transfer from the non-hydrogenated DLC to the contact surface of the Mg pin was observed in argon. Changing the test atmosphere from argon to ambient air increased the COF to 0.40, which was accompanied by the formation of oxidized Mg debris and an increased wear rate. The friction and wear mechanisms of non-hydrogenated DLC coatings against Mg are proposed to rationalize experimental observations.