SnBi-based lead-free solders are widely used for low-temperature interconnections due to their low melting point and favorable mechanical properties. However, SnBi solder joints are prone to high brittleness and a coarse Bi phase after aging, resulting in reduced joint stability. To address these limitations, in this study, a 7-wt.

The corrosion interface characteristics and corrosion behavior of Cu-C alloys in liquid Ga at 100-180 degrees C were studied in this paper. The corrosion mechanism of Cu-C alloys was microscopically studied via the first-principles calculation based on the density functional theory (DFT). The results, the diffusion of Ga atoms leads to the phase transition of Cu in the Cu-C alloy and the generation of the corrosion product CuGa2. The corrosion rate of the Cu-C alloy is related to the dissolution rate, and growth rate and exfoliation rate of corrosion product layer. C led to much better corrosion resistance of Cu-C alloys.

This study aims to explore a preparation method based on a combination of melting and ultrasound to produce a Ga2O3/ZnO (GZ) spherical composite with a snake raspberry structure for the degradation of methyl orange at room temperature in dark. The catalyst exists in the form of a (GZ) composite and an anhydrous ethanol mixture after the ultrasonic treatment of premelted GaZn liquid metal alloy in anhydrous ethanol. The degradation activity of the catalyst was evaluated according to the amount of catalyst, alloy extraction temperature, acid–base environment, and inorganic salt ions. A transmission electron microscope (TEM) was used to confirm that the material was Ga2O3 coated with ZnO, with a structure similar to that of snakeberry. The electron paramagnetic resonance (EPR) and a series of free radical inhibition experiments demonstrated that ·O2− is produced during the ultrasonic preparation of the catalyst and plays an important role in the degradation process after adding MO. The removal rate of MO reached 99.75% at 3 min. Three possible degradation pathways were proposed based on the intermediates produced during the degradation process, which were identified by liquid chromatography–mass spectrometry (LC–MS). The results of this study may provide a new choice for the degradation of organic pollutants.

The interface characteristics and corrosion behavior of Cu/C composites subjected to static corrosion in liquid gallium (Ga) were investigated. The results revealed that the wettability of Cu/C composites and liquid Ga was weakened by C phase, and the progress of corrosion was effectively hindered by C phase. At 720 h following corrosion, the corrosion thickness loss of Cu/C composites was only 33.37% of that of Cu. The corrosion products of Cu/C composites and Cu in liquid Ga were CuGa2. The CuGa2 and the residual C phase generated by the corroded Cu/C composites formed a mixed corrosion product layer, effectively preventing the composites from being corroded by liquid Ga. The diffusion of atoms can be blocked by C phase during the corrosion process, and thus the corrosion of the Cu/C composites and the growth of CuGa2 are inhibited.

文章以连接成形及增材制造设备及工艺课程为例,探索工科专业课程思政的教学目标、思政元素引入形式、情境设计和实施方式等,挖掘其蕴含思政元素的资源以及探索其与受教育者相契合的教育教学模式.经实施发现,开展"工程应用—实际问题—解决问题的人—职业素养的培养—价值观的树立"五步递进的项目引导式课程思政,能够使学生有效融入教学情境,学生的思想品质和专业素养也得到了明显提高.

Mini-LED backlights, combining color conversion materials with blue mini-LED chips, promise traditional liquid crystal displays (LCDs) with higher luminance, better contrast, and a wider color gamut. However, as color conversion materials, quantum dots (QDs) are toxic and unstable, whereas commercially available inorganic phosphors are too big in size to combine with small mini-LED chips and also have strong size-dependence of quantum efficiency (QE) and reliability. In this work, we prepare fine-grained Sr 2 Si 5 N 8 :Eu 2+ -based red phosphors with high efficiency and stability by treating commercially available phosphors with ball milling, centrifuging, and acid washing. The particle size of phosphors can be easily controlled by milling speed, and the phosphors with a size varying from 3.5 to 0.7 μm are thus obtained. The samples remain the same QE as the original ones (∼80%) even when their particle size is reduced to 3.2–3.5 μm, because they contain fewer surface suspension bond defects. More importantly, SrBaSi 5 N 8 :Eu 2+ phosphors show a size-independent thermal quenching behavior and a zero thermal degradation. We demonstrate that red-emitting mini-LEDs can be fabricated by combining the SrBaSi 5 N 8 :Eu 2+ red phosphor (3.5 μm in size) with blue mini-LED chips, which show a high external quantum efficiency (EQE) of above 31% and a super-high luminance of 34.3 Mnits. It indicates that fine and high efficiency phosphors can be obtained by the proposed method in this work, and they have great potentials for use in mini-LED displays.

The effect of Si on the corrosion of an Fe-B-Si alloy in liquid zinc was investigated. Corrosion tests of Fe-B-Si were conducted in a pure zinc bath (99.99 wt pct Zn). The results indicated that Si in α-Fe phase had a significant effect on the structure and evolution of corrosion interfaces in a directional Fe-B-Si alloy immersed in liquid zinc. Moreover, Si enrichment of the corroded interface induced changes in the mode of element diffusion, thereby affecting the Fe-Zn reaction and the quantity and volume of Fe-Zn compound. The Fe-Zn compound was occluded with the residual Fe2B closest to the corrosion interface, this structure could prevent direct contact between the liquid zinc and the alloy, and firm rooting of the compound at the interface. Therefore, Si in α-Fe phase had a significant effect on the corrosion resistance of Fe-B-Si alloy in liquid zinc. At a Si content of 0.318 wt pct, the densest composite corrosion product layer and highest corrosion resistance were obtained.

在Sn-9Zn二元合金中加入(1～4)wt％的Bi元素和1wt％的Ga元素得到新型低温无铅钎料,并进行了铜和铜的钎焊连接,并与三种传统含铅钎料钎焊铜/铜接头进行对比.探究了钎焊接头界面组织及其形成机理,分析了Bi和Ga元素对接头界面组织和力学性能的影响.结果 表明,焊接接头区组织中黑色棒状富Zn相随着Bi元素的增加逐渐减少并变得细小;在接头区有颗粒状组织形成,经XRD和EDS分析为Cu5Zn8相和Cu6Sn5相;当Bi元素含量为3 wt％时接头剪切强度和维氏硬度最高,分别为38.60 MPa和39.8 HV0.2.Bi含量为3wt％的低温无铅钎料钎焊性能最优,接头力学性能最优.

The new composite solder Sn-5Zn-10Bi-10In-xCr (x=0%, 0.1%, 0.3%, 0.5%, mass fraction) was made by adding different contents of nano-Cr particles to the Sn-Zn-Bi-In solder. The effect of nano-Cr particles on the microstructure, element distribution, phase composition and mechanical properties of brazing joints before and after aging was studied. The results show that the addition of nano-Cr particles can inhibit the growth of intermetallic compounds (IMCs) in the solder joints. With the increase of the content of nano-Cr particles, the thickness of the IMCs diffusion layer is gradually decreased; the IMCs diffusion layer at the interface near the base material Cu is Cu5Zn8 phase, and the side close to the solder zone is the Cu6Sn5 phase; as the aging time increases, the Cu5Zn8 compound on the solder side grows and is decomposed, and the Cu3Sn phase is formed; the nano-Cr particles inhibit the further growth of the IMCs diffusion layer during the aging process; as the content of Cr particles increases, the shear strength and microhardness of the solder joints increase first and then decrease. The shear strength and hardness of the Sn-5Zn-10Bi-10In-0.3Cr/Cu solder joints are the highest; the shear strength is lower than before aging, but the addition of nano-Cr particles keeps the solder joints with good shear strength. After aging, the microhardness of the solder area of the solder joints increases compared with that before aging, but it has always been maintained at below 30HV(0.1).

以Al-KBF4为反应体系,采用熔盐反应法制备了原位自生3％AlB2/6061复合材料(质量分数),对比6061基体材料,研究了AlB2颗粒对复合材料组织、 硬度和耐磨性能的影响.结果表明,在6061基体材料中原位自生了六边形AlB2颗粒,颗粒尺寸为0.5～2.0μm.经T6热处理后,3％AlB2/6061复合材料的硬度为HB 119.1,较6061基体提高了26.57％.复合材料比磨损率为1.83×10-8 kg·N-1·m-1,较6061基体下降了17.94％.AlB2颗粒与基体材料之间的润湿性好,界面结合强度高,且其本身硬度高,在磨损时能够起到承载作用,有效地减少了复合材料与对磨材料间的接触面积,提高了复合材料的耐磨性.复合材料的磨损机制主要为磨粒磨损和粘着磨损,其平均摩擦系数为0.235,相较于6061基体材料降低了17.54％.

The influence of the Si content and corrosion temperature on the formation of the compact multiphase corrosionproduct layer when Fe-B-Si alloys were corroded in liquid zinc, was studied. Si was enriched at the corrosion interface and dissolved in the corrosion product layer, thus, affecting the diffusion of Zn and Fe. The multiphase corrosion product layer composed of Fe-Zn compounds with residual Fe2B at the corrosion interface was formed. The Fe-Zn compounds are tightly occluded among the residual Fe2B phase, which can inhibit diffusion. The Fe-Zn compounds tend to dissolve at high temperatures. However, because the complete residual Fe2B skeleton structure was retained and a small number of compounds remained among the residual Fe2B skeletons, the inhibition of the multiphase corrosion product layer did not cease. When the Si content was 0.318 wt%, the corrosion product layer was the densest, and when the Si content was 0.196 wt%, the corrosion product layer had the weakest diffusion-inhibition effect.

以Al-Al2O3-B2O3为反应体系,采用接触反应法制备了原位自生Al18B4O33w/6061复合材料,利用XRD和SEM对复合材料分别进行物相分析及微观形貌观察,对比6061基体材料,研究了Al18B4O33晶须对复合材料硬度和耐磨性能的影响.结果 表明,采用接触反应法,利用Al-Al2O3-B2O3反应体系可直接在6061基体材料中原位自生针状Al18B4O33晶须,Al18B4O33晶须直径为0.1～2 μm,晶须伴生于Mg元素.经T6热处理后,Al18B4O33w/6061复合材料的硬度为HB 132.7,较6061基体提高了27.4％,硬度的提高机制为位错强化和细晶强化.Al18B4O33w/6061复合材料的比磨损率和平均摩擦系数分别为1.96×10-8 kg/(N·m)和0.221,较6061基体下降了12.11％和22.46％.采用原位自生工艺制备的Al18B4O33w/6061复合材料,晶须与基体材料之间的润湿性和界面结合强度良好,且晶须本身强度高,在磨损时能够起到支撑作用,减小了基体的应变和磨损,有效地提高了复合材料的耐磨性.

在进行热镀锌工艺生产时,稳定辊、沉没辊、轴套等设备在连续运转过程中与锌液发生强烈腐蚀反应,明显降低设备使用的寿命,是热镀锌行业亟待解决的问题之一.针对热镀锌工业钢铁设备存在的腐蚀问题,从材料和机理角度综述了几类工业设备用钢铁材料的耐锌液研究进展,总结了研究中存在的不足,介绍了对锌液腐蚀产生重要影响的“Sandelin”效应,指出基于“Sandelin”效应研究耐锌液腐蚀性材料将成为今后重要的研究方向.

采用接触反应法制备了原位自生Ti Cp/6061复合材料,利用XRD和SEM对复合材料进行物相分析及微观形貌观察,用6061铝合金基体材料作为对比,研究了增强粒子含量对复合材料硬度和摩擦磨损行为的影响。结果表明,采用接触反应法,以Ti粉、C粉和Al粉作为生成Ti C增强相的原材料,可直接在6061铝合金基体中原位生成Ti C颗粒,Ti C颗粒呈规则多边形,尺寸为0. 5～1μm。随着增强粒子含量的增加,原位自生Ti Cp/6061复合材料的硬度明显提高,T6热处理后5%（质量分数）的Ti Cp/6061复合材料的硬度为120. 5HBS,比基体6061铝合金提高了28. 1%。这是Ti C颗粒对6061基体材料的位错强化和细晶强化综合作用的结果。此外,随着增强粒子含量的提高,原位自生Ti Cp/6061复合材料的耐磨性也增强; T6热处理后,在100 N恒压作用下与GCR15材料对磨300 s,基体6061铝合金失重是5%（质量分数） Ti Cp/6061复合材料的2倍。其原因在于Ti C颗粒含量的提高减小了对磨材料与复合材料的有效接触面积,从而增强了原位自生Ti Cp/6061复合材料的耐磨性能。

An Eshelby particle-compounded model was employed to investigate the stress distribution in the SiCp/Fe composites during straining in order to predict the stress-strain curves of the composites. Effect of the SiC volume content and aspect ratios on yield strength of the SiCp/Fe composites was studied by the simulation. The modeling results indicate that the stress in the iron matrix is much smaller than that in SiC particles as straining the composites, which means the strengthening mechanisms of the SiCp/Fe composites is determined by the load transfer mechanisms. The aspect ratios of the particles play a significant role in yield strength of the SiCp/Fe composites especially as the particle volume content is large. The stress in SiC particles has a stronger dependence on the aspect ratios of the particles only if the reinforcement volume content is small.

醇基涂料在生产中的用量巨大,是铸造工艺中必不可少的一部分.由于其中以煤粉这一化石能源材料为主要骨料,存在消耗量过大而受限,成本较高等特点.配制涂料选择新的生物质能代替煤灰,不仅增强了醇基涂料的稳定性等工艺性能,颜色、硬度、透气性等工作性能也都有相应改变,特别是铸造过程的流动性效果显著提高,能够为铸造涂料中骨料成分提供新的选择.

采用静态腐蚀的方法,借助扫描电镜、能谱仪和X射线衍射等分析手段,研究了Fe-3.5B合金在720～800℃静态铝液中的界面形态和腐蚀行为.结果表明,Fe-3.5B合金在不同温度下表现出较为稳定的腐蚀行为,Fe2B相能够阻挡铝液对基体的腐蚀,FeB和Fe-A1化合物结合形成的抑制层能够有效抑制Al向合金中的扩散,将Al和基体隔离,进一步阻碍腐蚀反应的进行,铝液温度对腐蚀界面残余Fe2B长度、Fe-Al化合物类型和致密性以及腐蚀界面结构都具有显著影响.

The interfaces and erosion of oriented Fe-B alloy in flow zinc at various erosion angles were investigated. The results indicate that oriented Fe-B alloy exhibits better erosion resistance at 90 degrees erosion. Erosion angle can strongly affect erosion resistance, which depends on not only the interfacial structure but also the epitaxial zeta accumulation. Meanwhile, cavitation erosion pits and interface spallation occur, which may be suppressed by zeta accumulation at 90 degrees erosion, thus strengthening the adhesion of product films. (c) 2017 Elsevier B.V. All rights reserved.

The effects of erosion angle and Fe2B orientation on cavitation erosion and interface structures of a directionally solidified (DS) Fe-B alloy in flowing liquid zinc were investigated to clarify erosion mechanism of liquid metal. The results indicate that the cavitation erosion rate of DS Fe-B alloy with Fe2B [001] orientation vertical to interface exhibits better erosion cavitation resistance. Erosion angle can strongly affect erosion performance that depends not only on interfacial orientation structure but also on local microturbulence. Erosion morphologies manifest that an obvious cavitation erosion occurs in strong flowing zinc disturbed and agitated zone, which results in severe cavitation pits and slip deformation of products, thus stimulating subsequent localized corrosion and pit-aggregation cracks. Cavitation erosion craters coupled with performance variations confirm that microturbulence-assisted fluid eddies and backflow are responsible for the cavitation pits. The combined effects of flow pattern and interface orientation significantly govern the epitaxial grown ζ removal/accumulation behaviors and multiphase pinning film adhesion. A model of hydraulic liquid-hammer action by cavitation-induced microjet and interface orientation interaction is proposed and discussed to account for cavitation pits and slip cracking, which reveals underlying erosion mechanism and material design of DS Fe-B alloy in flowing liquid zinc.

The erosion behavior of a directionally solidified Fe–B alloy containing 3.5 wt% B in the different velocities of flowing liquid zinc is investigated by X-ray diffraction and scanning electron microscopy to clarify the effect of interaction between Fe2B and the erosion products on erosion performance using a rotating-disk technique. The results indicate that the Fe–B alloy erodes at a low and steady rate in flowing liquid zinc. The microstructure of erosion layers of the directionally solidified Fe–B alloy depends on the orientation relation between the growth direction of Fe2B phase and the erosion surface. When the growth direction of Fe2B is perpendicular to the erosion surface, the Fe2B and the erosion compounds form a compact and stable combining layer that effectively inhibits the erosion of flowing liquid zinc and further improves the erosion resistance of Fe–B alloy.