HgNO_3法测定黄铜内应力腐蚀开裂的研究

利用HgNO3试验法对HgNO3引致铅黄铜(HPb59-1)内应力腐蚀开裂行为进行了研究.采用光学显微镜以及扫描电镜分析了腐蚀后铅黄铜的组织和断口形貌.结果表明:Hg沿晶界扩散削弱了基体原子间的结合力,同时Pb在晶界处偏聚,促使晶界脆化,从而加速了合金的开裂;断口致密度分析表明:该HPb59-1黄铜具有明显的分层等缺陷,说明黄铜在锻造过程中存储了大量的内应力.     

黄铜型材在HgNO3溶液中腐蚀开裂行为初探

用HgNO_3试验法对HgNO_3引致铅黄铜(HPb63-3)应力腐蚀开裂行为进行了初步分析.结果表明,其原因主要是Hg沿晶界扩散削弱了基体金属原子间的结合力,同时也由于Pb,Zn在晶界处的偏聚,从而加速了晶界脆化.     

无铅易切削黄铜的研究

针对目前机械制造业普遍使用的易切削黄铜所含铅元素对环境造成的危害 ,分析铅黄铜的易切削原理 ,选取适当的合金元素加入到无铅黄铜中 ,通过多次试验不断改良切削性能 ,检测其耐蚀性能 结果表明 ,加入适量的Si等元素取代Pb ,也可实现其易切削性能 ,同时改善其耐蚀性能     

无铅HSi76—3．2硅黄铜组织性能的研究

普通黄铜具有优良的机械性能、耐蚀性能、导电导热性能及加工性能,从而得到广泛应用．普通黄铜是合铅的铜锌合金,由于铅可损害人体骨髓造血系统和神经系统,研究无铅的环保型黄铜成为现时的主要课题．主要研究了无铅黄铜H5i76—3．2的组织和性能,对H5i76—3．2硅黄铜进行了去应力退火和再结晶退火处理,测试了不同状态HSi76—3．2硅黄铜的力学性能和切削性能,对其进行了光学显微组织观察、断口形貌、能谱等分析．结果表明,HSi76—3．2硅黄铜显微组织由深色相Cu5Si＋Cu7Zn3（a）和浅色相Cu5Si＋Cu5Zn4（β）及第三相7相或Mg、Si、Ca、K、Al的氧化物等组成,再结晶退火后深色相Cu。Si＋Cu,Zn。（a）中出现大量的孪晶组织．显微组织中深黑色第三相具有高硬度相,是保证HSi76—3．2材料有良好切削性能的主要因素．HSi76—3．2经不同处理后的力学性能有较大的变化,其断裂形式均为韧性断裂．HSi76—3．2是一种良好的普通黄铜的替代品．     

正交试验法在无铅黄铜成分设计中的应用

用正交试验法研究了无铅黄铜制备过程中合金元素Sb、Ce和Ti对合金抗拉强度、抗脱锌性能以及切削性能的影响.通过正交试验法得出最优化合金成分为wCu∶wZn∶wSb∶wCe∶wTi=58∶40.5∶0.8∶0.4∶0.3;锑的质量分数是影响合金综合性能的主要因素,其次是Ce含量,Ti影响很小;优化后制备出的合金抗拉强度为461.7MPa,屈服强度为213.3 MPa,延伸率为15.67%,合金平均脱锌层厚度约为255.05μm,合金切削性能较好.     

凝汽器黄铜管冲刷腐蚀模拟试验装置及初步研究

自制了冲刷腐蚀模拟试验装置,对 Ｈ Ｓｎ７０ － １ Ａ 铜管进行了模拟试验,表明凝汽器黄铜管管端冲刷腐蚀较管内严重,是管内的１４ 倍．     

Examination of dynamic recrystallization during compression of AZ31 magnesium

This study aimed to investigate dynamic recrystallization (DRX) behavior during compression of magnesium alloy AZ31. Cylinder samples were cut from the extruded rod and hot rolled sheet AZ31 for compression test. The samples were compressed using a Gleeble 1500D at a temperature of 300℃ and a strain rate of 0.01 s-1. Grain orientations and misorientation angles across grain boundaries for the tested samples were obtained by using electron backscatter diffraction (EBSD) technique. The results showed that strong basal texture was observed after 50% compression (ε = 0.69) on both the extruded and hot rolled samples, which have different initial textures. It was observed that with increased strain, DRX grains gradually rotated to basal orientation, and grain boundaries with misorientation angle of near 30° was formed in the samples. At the strain of 0.69, a high fraction of high-angle (> 60°) bounda-ries was present in the extruded sample, whereas almost no high angle boundaries were observed in the hot rolled sheet sample.     

醋酸对黄铜管腐蚀行为影响的模拟研究

微生物的代谢产物——醋酸，对黄铜管的耐蚀性能影响较大．通过对黄铜管在不同醋酸浓度的循环水中的电化学阻抗谱(EIS)的测定和拟合，确定了合适的模型．根据此模型循环，在循环水中加入少量醋酸，可使膜电阻R1和电荷转移电阻R2的值大大减小，而膜电容C1和双电层电容C2的值均有增大，这表明黄铜管的耐蚀性能大为降低．     

盐酸溶液中三乙烯四胺基双二硫代甲酸钠对黄铜的缓蚀作用

采用失重法、电化学极化曲线和电化学阻抗谱考察了pH=2的HCl溶液中三乙烯四胺基双二硫代甲酸钠（DTC-TETA）对黄铜的缓蚀作用.挂片实验表明,20 mg/L的DTC-TETA对黄铜的缓蚀效率可达88.2%.电化学测量表明,DTC-TETA使黄铜的自腐蚀电位负移至-115.2 mV,抑制了黄铜电极的阴极还原过程,提高了黄铜电极表面的电荷转移电阻,具有较好的缓蚀效果.     

Modeling and simulation of crushing process of spiral mining head

1 INTRODUCTIONThe research of mining deep seabed cobalt-richcrust is a hotspot of international oceanology[1].Based on the mining manganese nodule ,lots of re-searches on mining cobalt crust have been madedeeply and many kinds of methods ,such as thei m-proved CLB, mining vehicle +lifting system +surface supporting ship have been put forward.Mining vehicle consists of collecting machine ,tracked treading machine and spiral mininghead[2 ,3].The first step of mining cobalt crust is tocrush…     

FRICTION AND WEAR BEHAVIOUR OF SINTERED BRASS

ＦＲＩＣＴＩＯＮＡＮＤＷＥＡＲＢＥＨＡＶＩＯＵＲＯＦＳＩＮＴＥＲＥＤＢＲＡＳＳＦＲＩＣＴＩＯＮＡＮＤＷＥＡＲＢＥＨＡＶＩＯＵＲＯＦＳＩＮＴＥＲＥＤＢＲＡＳＳ￥ＬｉＸｉｂｉｎ；ＴａｎＬｉｎｙｉｎｇ；ＳｕＣｈｕｎｍｉｎｇ；ＬｉＭｅｉｙｉｎｇ（Ｐｏｗｄｅｒ...     

磁场作用下苯并三氮唑对黄铜的缓蚀性能研究

采用极化曲线和交流阻抗谱研究了苯并三氮唑(BTA)对黄铜/模拟水腐蚀体系的缓蚀作用,以及电磁场作用下BTA对黄铜电极缓蚀性能的变化.结果显示,BTA对该体系有较好的缓蚀作用;电磁处理和BTA联合作用时,腐蚀电流密度较缓蚀剂单独作用时进一步下降;电磁处理促进了缓蚀剂BTA在金属表面的吸附;在一定时间范围内,磁处理时间越长,BTA对黄铜电极的缓蚀性能越好.     

黄铜真空蒸馏脱锌的研究

研究了不同 黄铜在真空蒸馏条件一的分离情况，结果表明，用真空蒸馏法可以分离黄铜中的锌，对黄铜脱锌的规律性和影响挥发速率的因素，如温度，真空度，锌在原料中的含量等作了一定的研究。     

自蔓延高温合成法（SHS）制备致密的Al_2O_3－TiC陶瓷

采用电热爆－加压法（ＥＴＥ－Ｐ）和燃烧合成制粉＋加压法（ＳＨＳ＋ＨＰ）制备了致密的Ａｌ２Ｏ３陶瓷．研究表明，ＳＨＳＡｌ２Ｏ３－ＴｉＣ陶瓷的力学性能和切削性能均优于采用传统热压方法所制备的Ａｌ２Ｏ３＋ＴｉＣ陶瓷刀具，并对ＳＨＳＡｌ２Ｏ３＋ＴｉＣ的的显微结构及致密化机制作了研究．     

AZ80镁合金管材热挤压工艺及组织性能研究

选用不同的工艺参数对变形镁合金AZ80进行管材热挤压工艺实验研究;对挤压前后材料组织与力学性能的变化进行分析。研究结果表明：热挤压可以显著细化AZ80镁合金的晶粒,而且随着挤压比的增加,晶粒变得更加细小;增大挤压比也可以提高AZ80镁合金的抗拉强度和屈服强度。挤压比为18.2,坯料温度为390℃,模具预热温度360℃,凹模的半模角为60°～70°,可得到均匀的合金组织和良好的力学性能.     

Multi-objective Optimization in the Milling of Titanium Alloys Using the MQL Technique

The process for face milling of (α β) titaniwn alloy while using minimum quarttity librication (MQL) as the cooling technique was optimized by using of the Taguehi method to improve characteristics. The cutting speed, feed rate, and depth of cut were optimized with consideration of multiple performance characteristics including tool life, volume removed and surface roughness. The experimental results show that the nudtiple performance characteristics can be simultaneously improved through this approach, and the feed rate is the most influential cutting parameter in the face milling of titanium alloys.     

挤压温度对固相再生ZM6镁合金组织和性能的影响

利用固相再生方法在挤压比为25：1的条件下,将ZM6镁合金屑分别在350℃、400℃、450℃和500℃温度下制备成试样,进行微观组织观察和力学性能测试。结果表明：当挤压温度为400℃时,ZM6耐热镁合金没有发生再结晶,合金中金属化合物在挤压过程中被打碎,均匀分布在基体中;当挤压温度为450℃和500℃时,ZM6镁合金发生部分动态再结晶;随着挤压温度的提高,合金的抗拉强度和延伸率提高;在挤压温度为500℃,合金的抗拉强度、屈服强度和延伸率分别为300．2MPa、142．9MPa和30％。合金室温拉伸断口主要表现为穿晶韧窝断裂。     

Chip-ejection interference in cutting processes of modern cutting tools

Based on the “principle of minimum energy”, the basic characteristics of non-free cutting are studied; the phenomenon and the nature of chip-ejection interference commonly existing in the cutting process of modem cutting tools are explored. A "synthesis method of elementary cutting tools" is suggested for modeling the cutting process of modem complex cutting tools. The general equation governing the chip-ejection motion is deduced. Real examples of non-free cutting are analyzed and the theoretically predicted results are supported by the experimental data or facts. The sufficient and necessary conditions for eliminating chip-ejection interference and for realizing free cutting are given; the idea and the technical approach of "the principle of free cutting" are also discussed, and a feasible way for improving or optimizing the cutting performance of modem cutting tools is, therefore, found.     

Corrosion inhibition of low phosphonic multipolymer water treatment agent of industry circulating on brass in aqueous solution

In response to environmental guidelines, a low phosphonic multipolymer was synthesized and its corrosion inhibition efficiency to brass in synthetic water was investigated through weight loss measurements and electrochemical tests. It showed that the synthesized inhibitor decreased corrosion under the conditions tested. Potentiodynamic polarization curves indicated that the new inhibitor acted as an anodic inhibitor, reducing metal dissolution. The composition of protective films formed on the brass was studied by energy-dispersive X-ray analysis （EDX）. The inhibition effects were due to the formation of a protective film of the multipolymer inhibitor on the metal surface.     

热处理对锻造铅黄铜组织和性能的影响

研究了退火温度对锻造铅黄铜组织和力学性能的影响.对铸造成型的商用铅黄铜进行720℃、60%变形量的锻造镦粗加工后,采用500~700℃不同温度的热处理工艺处理.结果表明：铅黄铜的铸态组织为粗大的树枝晶,锻造后的晶粒被拉长,与铸态的硬度值相比,锻造后的硬度明显增加,产生明显的加工硬化现象;锻造铅黄铜经过热处理后,细长的晶粒明显变短,随着退火温度的升高,晶粒逐渐细小、均匀化,并且发生再结晶,拉长的晶粒逐渐变为等轴晶.620℃、640℃退火后,铅黄铜的组织基本转变为细小、均匀的等轴晶,退火温度超过640℃时,随着温度的升高,晶粒长大.不同温度退火处理后,随着退火温度的升高,硬度逐渐降低,620℃退火后硬度趋于稳定,加工硬化消除.铅黄铜经720℃、60%变形锻造后,合适的退火温度为620~640℃.