Ni-rGO增强Sn2.5Ag0.7Cu0.1RE复合钎料/Cu钎焊接头电迁移组织与性能

借助扫描电子显微镜、能谱仪、X射线衍射仪和微剪切试验等手段,研究了镀镍还原氧化石墨烯(Ni-rGO)增强Sn2.5Ag0.7Cu0.1RE复合钎料/Cu钎焊接头电迁移组织与性能。研究结果表明:在恒温120℃、电流密度1×10~4 A/cm~2条件下,随着通电时间的增加,Ni-rGO增强Sn2.5Ag0.7Cu0.1RE复合钎料/Cu钎焊接头电迁移阳极区金属间化合物(IMC)层Cu_6Sn_5和Cu_3Sn平均厚度增大,阴极区界面IMC层Cu_6Sn_5平均厚度减小、Cu_3Sn平均厚度先增大后减小。Ni-rGO的添加,明显抑制了Ni-rGO增强Sn2.5Ag0.7Cu0.1RE复合钎料/Cu钎焊接头电迁移阳极区Cu_6Sn_5的生长及阴极区微空洞的生成,提高了钎焊接头剪切强度。通电72 h后,Ni-rGO增强Sn2.5Ag0.7Cu0.1RE复合钎料/Cu钎焊接头的剪切强度较未添加Ni-rGO的提高了47.8%。复合钎料/Cu钎焊接头电迁移剪切断裂,由阴极钎缝区呈以韧窝为主的韧性断裂,向界面IMC由解理、准解理和少量韧窝组成的混合型断裂转变。     

Ni-GNSs增强Sn2.5Ag0.7Cu0.1RE复合钎料/Cu钎焊接头热迁移组织与性能

针对微焊点服役过程中由大温度梯度导致的热迁移问题,设计了一种热迁移试验装置,研究了复合钎料/Cu钎焊接头热迁移过程中的组织演变与力学性能.研究结果表明:设计的试验装置可满足单一热迁移试验条件.与未热加载时相比,Ni-GNSs增强Sn2.5Ag0.7Cu0.1RE复合钎料/Cu钎焊接头热迁移200 h后,接头热端Cu6 Sn5界面金属间化合物(IMC)大幅减薄并在界面出现微孔洞;冷端界面粗大扇贝状IMC厚度明显增加,冷端Cu/Cu6 Sn5界面间生成平均厚度1μm的层状IMC Cu6 Sn5.热加载200 h后,钎焊接头剪切强度降低33％.复合钎料钎焊接头断裂位置由热端界面IMC/钎缝的过渡区向界面IMC方向迁移;随热加载时间增加其断裂机制由韧性断裂向先转变为以韧性断裂为主的韧-脆混合断裂,再转变为以脆性断裂为主的韧-脆混合断裂.Ni-GNSs增强相的添加可抑制复合钎料/Cu钎焊接头的热迁移.     

Cu含量对Sn基无铅钎料组织、界面反应影响

研究了Cu含量对Sn-xCu(x=0.7%,2%)、Sn-9Zn-xCu(x-0.2%,10%)两种无铅钎料的基体组织以及与Cu基板短时间钎焊时界面金属间化舍物(IMC)生长行为的影响.结果表明,当Sn-Cu钎料中Cu的含量为2%时,基体中IMC租化为块状的Cu6Sn5相;对于Sn-9Zn-xCu钎料合金,2%Cu元素的加入使得Sn-9Zn基体中长针状的富Zn相转化为Cu5Zn8相以及细小的富Zn相,而当Cu含量达到10%时,钎料基体中的IMC为CuZn相与Cu6Sn5相.在260℃短时间钎焊下,Cu含量的增加加速了Sn-xCu/Cu界面IMC的粗化和生长;而对于Sn-9Zn-xCu/Cu,Cu含量的增加却明显降低了界面IMC的生长速率.同时分析、讨论了界面IMC随钎焊时间变化的生长行为.     

Sn2.5Ag0.7Cu0.1RE/Cu钎焊接头电迁移组织与性能

研究了温度对Sn2.5Ag0.7Cu0.1RE/Cu钎焊接头电迁移组织与性能的影响。随着环境温度从100℃升高到140℃,及通电时间从24 h延长到72 h,Sn2.5Ag0.7Cu0.1RE/Cu钎焊接头阴极侧界面间金属化合物(IMC)Cu_6Sn_5逐渐变薄,由"扇贝状"变为"锯齿状"。阳极侧界面间IMC逐渐增厚,由"扇贝状"不断长大并形成凸起的小丘,且在母材接合处出现一层薄薄的Cu3Sn层。界面阳极侧IMC增加的厚度比界面阴极侧IMC减少的厚度大。Sn2.5Ag0.7Cu0.1RE/Cu钎焊接头剪切强度持续降低。随着温度升高,相应的剪切断口由钎缝区的解理与韧窝共存在的混合型断裂,逐渐变为界面阴极侧IMC的以解理为主的脆性断裂。     

Ni-rGO增强Sn2.5Ag0.7Cu0.1RE复合钎料钎焊接头显微组织与性能

采用粉末熔化法制备了镍粒子修饰的还原氧化石墨烯(Ni-rGO)增强Sn2. 5Ag0. 7Cu0. 1RE复合钎料,借助于扫描电子显微镜和X射线衍射,研究了Ni-rGO增强Sn2. 5Ag 0. 7Cu 0. 1RE复合钎料钎焊接头的显微组织与性能。研究结果表明:Ni-rGO增强Sn2. 5Ag0. 7Cu0. 1RE复合钎料与Cu基板可实现良好焊接。在钎焊温度270℃、钎焊时间240 s时,复合钎料钎焊接头剪切强度为29. 7 MPa,高于Sn3. 0Ag0. 5Cu钎料钎焊接头。随着钎焊时间的增加,钎焊接头剪切断裂机制呈现由以韧窝为主的韧性断裂向韧窝和解理组成的韧-脆混合断裂转变,断裂途径由钎缝和界面金属间化合物(IMC)层组成的过渡区向界面IMC方向移动。复合钎料钎焊接头钎缝区由β-Sn和共晶组织组成,界面IMC层由Cu6Sn5和新相(Cu,Ni)6Sn5组成。Ni-rGO增强Sn2. 5Ag0. 7Cu0. 1RE复合钎料钎焊接头的IMC厚度、粗糙度增加,界面IMC显微组织由扇贝状转变为锯齿状。     

Sn2.5Ag0.7Cu0.1RE/Cu钎焊接头在热循环下的电迁移行为

自主设计了热循环下钎焊接头电迁移试验装置,探究了热循环下电流密度对Sn2.5Ag0.7Cu0.1RE/Cu无铅钎焊接头界面及组织性能的影响。研究结果表明:在电流密度达到7.0×10~3A/cm~2时,出现明显的电迁移现象。随电流密度增加,钎焊接头阳极区金属间化合物(IMC)厚度显著增加,增厚的化合物主要是Cu_6Sn_5;阴极区IMC厚度呈幂指数缓慢增加,主要表现为Cu_3Sn的生长,且在阴极区与钎缝过渡区域出现裂纹和孔洞。钎焊接头发生电迁移后剪切强度降低50%,断裂发生在阴极界面IMC上,剪切断口呈脆性断裂。     

Ni-GNSs增强Sn2.5Ag0.7Cu0.1RE/Cu钎焊接头电迁移特性研究

针对微焊点服役下的电迁移可靠性检测,设计制造了满足焊点在理想电迁移环境下的试验装置。结果表明：通过热分解法制备Ni-GNSs增强相,得到的Ni-GNSs增强Sn2.5Ag0.7Cu0.1RE/Cu钎焊接头能有效抑制电迁移现象的发生。在电加载条件下,随电流密度升高,Ni-GNSs增强Sn2.5Ag0.7Cu0.1RE/Cu接头阳极区界面金属间化合物(IMC)由起伏扇贝状转变为平坦厚大的板状,并出现了明显Cu₃Sn;阴极区界面IMC由锯齿状转变为薄条状,且有明显空洞裂纹。钎焊接头断裂位置从阴极界面IMC/钎缝的过渡区向阴极界面IMC迁移,断裂方式由韧性断裂向脆性断裂转变,剪切强度明显下降。     

低银Sn2.5Ag0.7CuxRE钎料合金的润湿特性

采用润湿平衡法,研究了水洗钎剂条件下Sn2.5Ag0.7CuxRE无铅钎料合金在1206片式元器件和Cu焊盘上的润湿特性.结果表明,添加0.1%(质量分数)稀土的Sn2.5Ag0.7Cu钎料合金在1206表面贴装元器件和Cu焊盘上有最大的润湿力和铺展面积及最小的润湿角,润湿性最好,其润湿力优于商用的Sn3.8Ag0.7Cu钎料合金,满足微电子连接用钎料对润湿性能的要求.     

时效处理对Sn57Bi0.5Ag/Cu钎焊接头组织及性能的影响

研究了Sn57Bi0.5Ag/Cu钎焊接头在70℃、100℃时效过程中的显微组织和剪切强度的变化。结果表明:在钎料和Cu基体的界面间存在金属间化合物,随时效时间的延长,界面金属间化合物层的厚度增厚,接头区的组织出现了粗化;脆性的金属间化合物是钎焊接头的薄弱环节,接头剪切强度随时效时间的增加和界面化合物的增厚而下降;在时效时间达1000min以后,容易在金属间化合物层内观察到空洞。     

高温时效下Sn/SnPb混装焊点的微观组织研究

针对Sn/Sn Pb混合组装焊点在工艺兼容性和长期可靠性方面存在的问题,设计了带菊花链结构的板级电路,采用回流焊接工艺对无铅方形扁平封装(QFP)器件和Sn Pb焊料实现混合组装,对组装样品进行1500 h的高温老化实验。通过对高温老化前后混装焊点显微组织的分析和电、力学性能的研究,探讨混装焊点两侧焊接界面金属间化合物(IMC)的生长规律及其对焊点电、力学性能的影响.结果表明:Cu6Sn5和Cu3Sn金属间化合物厚度均与老化时间的平方根呈线性关系,混装焊点界面的Cu6Sn5分解反应是Cu3Sn化合物的主要生长机制;老化过程中富铅相在焊接界面的聚集,切断了焊点内Sn原子的扩散通路,形成阻碍IMC层进一步生长的抑制区;焊点基体β-Sn的尺寸粗化、Pb的富聚以及具有本质脆性的IMC层状生长降低了焊点的抗拉强度,层状IMC的厚度在一定程度上反映了焊点的力学性能.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.