2A12合金加工件黑点缺陷原因分析

采用金相显微镜、扫描电镜和能谱分析设备,对2A12合金加工件的黑点缺陷进行了宏观、显微形貌特征及能谱结果综合分析。结果表明,加工件黑点缺陷形成原因是由于该部位存在氧化膜缺陷,在加工过程中暴露出来的表像。     

铝合金模锻件表面黑点的工艺控制

针对铝合金模锻件在机加工及阳极化后表面存在大量黑点缺陷的问题,通过对原材料及生产工艺进行长期跟踪分析与总结,得出原材料表面缺陷、加热过程表面带入杂质、型腔表面带有杂质、工具表面带入杂质等为黑点缺陷产生的主要原因,并从原材料和工艺过程控制方面制定相应的工艺改进方案以及预防措施,以减少表面黑点缺陷,提高铝合金模锻件的成品率。     

Q345B中厚板成型裂纹原因分析

针对用户使用Q345B中厚板产品时出现成型裂纹、冷弯裂纹现象,进行了成分分析、扫描电镜分析。结果显示:钢中硫、磷、氮含量超标且波动较大,引起了冷脆、显微缺陷、蓝脆缺陷。扫描电镜观察,钢板边部存在显微裂纹,大量条带状组织和大型硫化物,引起基体组织大量存在拉长夹杂与显微分层缺陷,导致钢板冷弯时边部产生裂纹。     

热镀铝锌硅镀层表面黑点缺陷原因分析

梅钢热镀铝锌硅产品在生产和加工的过程中,镀层表面偶发局部黑点缺陷。本文对2019年以来发生的黑点缺陷进行了微观形貌和能谱元素分析。结果表明,黑点缺陷产生原因可分为三类:镀层局部增厚、炉鼻锌灰、辊面异物。同时,根据分析结果,提出了预防黑点缺陷发生的控制措施。     

高级别表面耐指纹家电板黑点缺陷分析

高级别表面耐指纹家电板要求钢板表面近乎零缺陷。对于在生产过程中出现的表面黑点缺陷,采用扫描电镜(SEM)和电子探针(EPMA)进行分析。结果表明,黑点缺陷种类较多,不同的黑点缺陷产生于热镀锌机组不同部位,如后处理风箱、拉矫机等。通过对设备的调整和清洁等措施,可成功消除黑点缺陷。     

无取向硅钢环保涂层黑点缺陷成因分析与控制措施

随着环保政策的加强,近年来无取向硅钢环保涂层产品产量迅速增长。环保涂层液成分与传统含铬涂液成分不同,表面质量稳定性差,极易出现各种缺陷。在生产某无取向硅钢过程中,无取向硅钢表面出现黑点缺陷,对产线稳定性以及产品成材率产生较大影响。通过宏观观察、扫描电镜（SEM）、能谱分析、现场模拟实验等,对黑点缺陷产生的原因进行分析,并针对此类缺陷提出控制措施,有效降低了黑点缺陷发生率。     

201不锈钢产品横裂纹缺陷分析

检测分析中金公司201不锈钢产品横裂纹缺陷试样的化学成分、金相组织、缺陷微区成分认为:缺陷的主要产生原因是钢中存在较严重的脆性夹杂物和显微气泡。     

粉末冶金产品缺陷与显微组织

论述了铁基粉末冶金结构零件某些缺陷，如：裂纹、尺寸失控、力学性能不合格、不易切削等的内在显微组织分析。通过显微组织分析，找出产生缺陷的原因，从而提高工艺水平。     

EBM成型TC4钛合金研究进展

电子束熔化成型技术(electron beam melting,EBM)是3D打印的代表性技术之一,特别适合传统工艺不易加工的Ti-6Al-4V合金(TC4钛合金)的快速成型,目前在航空航天、化工、生物医疗等领域展示出巨大的应用前景。从EBM的原理出发,综述了EBM制备TC4钛合金的显微组织、缺陷以及力学性能。分析了受成型工艺参数和成型件位置等因素影响的冷却速度的变化所导致的TC4钛合金的显微组织发生变化;并指出了导致TC4钛合金出现缺陷的主要原因。EBM成型TC4钛合金的拉伸性能已与锻造TC4钛合金相当,其较低的疲劳强度可以通过热等静压处理提高。     

厚规格低碳低合金钢探伤缺陷原因分析

采用低倍、金相、显微硬度等检验手段,对厚规格低碳低合金钢板探伤缺陷进行了分析,确定造成探伤缺陷的原因是钢中存在严重的组织偏析,引起组织应力,与冷却时产生的热应力综合作用,使钢中塑性较差的区域出现裂纹。同时采取了轧后堆垛缓冷的控制措施,避免了钢中显微裂纹的出现。     

HOXD4 and regulation of the group 4 paralog genes

From an evolutionary perspective, it is important to understand the degree of conservation of cis-regulatory mechanisms between paralogous Hox genes. In this study, we have used transgenic analysis of the human HOXD4 locus to identify one neural and two mesodermal 3' enhancers that are capable of mediating the proper anterior limits of expression in the hindbrain and paraxial mesoderm (somites), respectively. In addition to directing expression in the central nervous system (CNS) up to the correct rhombomere 6/7 boundary in the hindbrain, the neural enhancer also mediates a three rhombomere anterior shift from this boundary in response to retinoic acid (RA), mimicking the endogenous Hoxd4 response. We have extended the transgenic analysis to Hoxa4 identifying mesodermal, neural and retinoid responsive components in the 3' flanking region of that gene, which reflect aspects of endogenous Hoxa4 expression. Comparative analysis of the retinoid responses of Hoxd4, Hoxa4 and Hoxb4 reveals that, while they can be rapidly induced by RA, there is a window of competence for this response, which is different to that of more 3' Hox genes. Mesodermal regulation involves multiple regions with overlapping or related activity and is complex, but with respect to neural regulation and response to RA, Hoxb4 and Hoxd4 appear to be more closely related to each other than Hoxa4. These results illustrate that much of the general positioning of 5' and 3' flanking regulatory regions has been conserved between three of the group 4 paralogs during vertebrate evolution, which most likely reflects the original positioning of regulatory regions in the ancestral Hox complex.     

Fourier Transform Infrared Emission Spectroscopy of the C4Delta-X4Phi, G4Phi-X4Phi, and G4Phi-C4Delta Systems of TiCl

The emission spectrum of TiCl has been investigated in the 3000-12 000 cm-1 region at high resolution using a Fourier transform spectrometer. The bands were excited in a microwave discharge through a flowing mixture of TiCl4 and helium. The observed bands have been classified into three electronic transitions, C4Delta-X4Phi, G4Phi-X4Phi, and G4Phi-C4Delta. In the 3000-3500 cm-1 region, four bands with R heads at 3368.7, 3331.8, 3291.9, and 3243.4 cm-1 have been assigned as the 0-0 bands of the 1/2-3/2, 3/2-5/2, 5/2-7/2, and 7/2-9/2 subbands, respectively, of the C4Delta-X4Phi transition. To higher wavenumbers, four transitions with 0-0 R heads at 10 930.7, 10 921.3, 10 906.5, and 10 886.9 cm-1 have been assigned as the 3/2-3/2, 5/2-5/2, 7/2-7/2, and 9/2-9/2 subbands, respectively, of the G4Phi-X4Phi system of TiCl. Four additional bands with 0-0 R heads at 7568.8, 7596.4, 7622.2, and 7651.7 cm-1 have been identified as the 1/2-3/2, 3/2-5/2, 5/2-7/2, and 7/2-9/2 subbands of the G4Phi-C4Delta transition, respectively. A rotational analysis of a number of vibrational bands of these transitions has been obtained and molecular constants have been extracted. The lowest 4Phi state has been assigned as the ground state of TiCl, by analogy with our recent work on TiF (R. S. Ram and P. F. Bernath, J. Mol. Spectrosc., in press). The correspondence between the electronic states of TiCl, TiF, TiH, and Ti+ is also discussed. Copyright 1997 Academic Press. Copyright 1997Academic Press     

4-丙基-4''''-氰基联苯的合成研究

以联苯为原料,经Friedel-Crafts反应、还原反应、碘代反应、氰化反应,合成4-丙基-4'-氰基联苯.此方法合成步骤少,操作简单,提纯方便,节省了费用.     

Partial phase diagrams of the ternary systems NaCl-KCl-ZrCl4 and NaCl-KCl-HfCl4

Abstract

Fluoride emissions especially hydrogen fluoride from the aluminium smelting process present the potential for significant environmental damage and the care is, therefore, taken to remove them from the gas stream that leaves the plant. While previous work has focused on improving the scrubbing efficiency, more recent research has investigated the generation of fluoride emissions during the reduction process, in part to understand seasonal changes in fluoride emissions (summer syndrome). Several models have been developed to estimate the amount of hydrogen fluoride generated, but these do not consider the individual sources of fluoride generation and cannot be easily used to assess the impact of changes in relative humidity. This paper presents a new model, still under development, which simulates the hydrolysis of pot gas from an open feeder hole. During the course of this research, it has become clear that the major sources of moisture for hydrogen fluoride generation appear to be alumina, in the form of structural hydroxides and the ambient humidity. It is thought that summer syndrome can be explained by the changes in the ambient humidity. Initial results suggest that, in an open feeder hole, a 3000–5000 ppm hydrogen fluoride (HF) background in pot gas presents, the ambient moisture could account for 30–55% maximum of total HF emission, varying with ambient humidity, CO flaming and bath chemistry. However, the anode hydrogen and adsorbed alumina moisture only have limited contribution to the gaseous fluoride.     

Determination of the diffusion coefficients of CuSO4, ZnSO4, and NiSO4 in aqueous solution

The diffusion coefficients of CuSO₄, ZnSO₄, and NiSO₄ in the aqueous solution systems of MSO₄ and MSO₄-H₂SO₄ were measured at 298 K using a diaphragm-cell method, and are listed as a function of molar concentrations of MSO₄ and H₂SO₄. It was found that the concentration dependencies of the diffusion coefficients for CuSO₄, ZnSO₄, and NiSO₄ in each single metal sulfate solution are very similar. The presence of H₂SO₄ generally causes a less significant concentration dependency of the diffusion coefficients of MSO₄. The concentration dependencies of the diffusion coefficients of CuSO₄ in aqueous solutions of CuSO₄ and CuSO₄-H₂SO₄ are attributed to the changes in the mean activity coefficient of CuSO₄ and the viscosity of the solutions. formerly Graduate Student, Department of Metallurgy, Kyoto University, Kyoto, Japan