PMN-PNN-PT单晶的固相法生长研究

采用两步法和埋入PMN-PT单晶为模板的等离子放电烧结（SPS）技术制备出了致密的单一钙钛矿相的PMN-PNN-PT陶瓷，随后在1200℃下退火100h来诱导晶体的生长。实验结果表明，PMN-PNN-PT单晶〈111〉方向的生长速度明显快于〈001〉方向，而〈111〉方向生长的晶体形状为V字形，这是由钙钛矿结构的生长机理决定的，钙钛矿结构晶体的生长是通过〈001〉方向的层状生长来实现的。     

活性化TIG焊熔深增加机理的研究

以不锈钢0Crl8Ni9为实验对象，涂敷含有Bi的SiO2和TiO2活性剂，通过1mm厚高熔点薄钨板挡住熔池流动的方法进行焊接实验．对钨板两侧Bi颗粒的分布进行了测试，分析涂敷SiO2和TiO2后熔池流动方向的变化，同时采集了电弧电压．结果表明：活性剂SiO2和TiO2改变了熔池的流动方向；SiO2使电压提高约4．2V，而TiO2对电弧电压没有影响；活性剂并未使电弧整体发生收缩，而使电弧整体发生了膨胀；SiO2使等离子体发生了收缩；电弧等离子体收缩和电弧导电通道变长是SiO2活性剂提高电弧电压的主要原因．分析认为，SiO2增加熔深是等离子体收缩、阳极斑点收缩和表面张力温度梯度由负变正共同作用的结果；TiO2增加熔深只是表面张力温度梯度由负变正的作用．     

Fe和两种工业钢在500℃含氯气氛中ZnCl2-KCl盐膜下的腐蚀

研究了纯Fe,NF616和SS304钢在500℃含氯气氛中ZnCl2-KCl盐膜下的腐蚀行为.结果表明,3种材料都发生了加速腐蚀,生成了较厚的氧化膜,且在氧化膜与基体金属之间出现了熔融状氯化物混合盐.此外,合金在此环境中的抗腐蚀性随其Cr含量的提高而显著提高,这是在腐蚀过程中氧化膜内层出现了Fe-Cr尖晶石或Cr2O3阻挡了金属离子快速向外扩散的结果.讨论了材料发生加速腐蚀的机制.     

球磨法制备钛纳米晶

用球磨法制备出钛纳米晶粉末.结果表明,经过24h球磨后,晶粒平均尺寸达到12—13nm粉末的氧、氮含量极低、粉末的硬度与晶粒尺寸的关系为正常的Hall-Petch关系。     

An initial study on welding procedure using tandem MIG welding of high strength aluminum alloy

The high-speed camera system and data acquisition system of welding parameters were created in tandem MIG welding of high strength aluminum alloy. The experiments were carried out in order to obtain the photos of droplet transfer under different welding parameters in pulsed mode. The droplet transfer mode of ““one pulse one droplet““ becomes the preferred selection during welding process because of its stable procedure and sound weld form. The parameter ranges for corresponding transfer mode were experimentally achieved, among which the stable droplet transfer mode of ““one pulse one droplet““ can be realized. These efforts brave the way for control weld heat input and weld formation in the future.     

2.25CrMo钢在还原性含氯气氛中的高温腐蚀行为

采用热重法及SEM／EDX，XRD研究了2．25CrMo钢在500和600℃下含氯还原性气氛中的腐蚀行为．结果表明，实验材料在两种温度下均发生了加速腐蚀，并且在外氧化膜／基体界面检测到了氯的存在．合金腐蚀动力学从500℃时的近似抛物线向600℃时的直线转变与氯化物在该温度下的蒸汽压有关．讨论了材料发生加速腐蚀的机制．     

预氧丝在氧化镁/炭复合材料中的原位碳化及其强化作用

研究了碳纤维前驱体即预氧丝在氧化镁／炭复合材料中原位碳化及其强化作用。在氧化镁／炭复合材料中存在铝、镁添加剂时，预氧丝原位碳化后具有碳纤维的强度和强化效果。预氧丝在添加硅粉的氧化镁／炭材料中原位碳化时因与硅反应失去强度，在无抗氧化添加物的氧化镁／炭材料中原位碳化后，预氧丝因氧化失去强度，对基体无强化作用。     

Extraction and separation of Ga(Ⅲ) and T1(Ⅰ) or In(Ⅲ) and T1(Ⅰ) from chloride media with CA-12 in sulphonating kerosene

The extraction behavior and mechanism of gallium(Ⅲ) and thallium(Ⅰ) or indium(Ⅲ) and thallium(Ⅰ) with Sec-octylphenoxy acetic acid (CA-12) from hydrochloric acid solution in sulphonating kerosene were studied. Optimum extraction conditions were evaluated from critical study of various experimental parameters and the probable composition of the extracted species is ascertained from lg D-lg C plots. The effects of different ions on the determination of these ions were examined.     

Micro-mechanical properties of 2219 welded joints with twin wire welding 

0IntroductionWith the rapid developmentof modern manufacturing,applications of aluminum alloy welded structures with bigthickness are becoming more and more widely. As a kindof efficient welding method, twin wire welding has suchmerits as big deposition rate, little heat input and narrowheat-affected zone. At the same time, the defects such asincomplete penetration, discontinuous beam or undercutcan be avoided effectively[1 -5]. 2219 aluminum alloy hasthe wider application foreground due to it…     

INFLUENCE OF RESIDUAL STRESS AND SURFACE MORPHOLOGY ON FATIGUE PROPERTIES OF STEEL 60Mn

Influence of residual stress and surface morphology induced by shot-peening on fatigue behav-ior of a medium temperature tempered spring steel 60 Mn has been studied.The compressiveresidual stress induced in the near-surface region may improve fatigue limit from 930 to 1010MPa,and the very high tensile residual stress in the interior may reduce it from 1010 to 940MPa,whereas the severe surface damage may cause a drop-off of it from 1010 down to 800MPa.Fatigue cracks initiated in such position where the equivalent Mises stress,includingresidual stress,exceeded the local strength of the material.The compressive residual stress,induced by shot-peening,may intensify the effect of crack closure,so as to decrease the crackgrowth rate.