Boron Nitride Nanosheets Strengthened PVA/Borax Hydrogels with Highly Efficient Self-Healing and Rapid pH-Driven Shape Memory Effect

Self-healing hydrogels often possess poor mechanical properties which largely limits their applications in many fields. In this work, boron nitride nanosheets are introduced into a network of the poly(vinyl alcohol)/borax (PVA/borax) hydrogels to enhance the mechanical properties of the hydrogel without compromising the self-healing abilities. The obtained hydrogels exhibit excellent mechanical properties with a tensile strength of 0.410 ± 0.007 MPa, an elongation at break of 1712%, a Young's Modulus of 0.860 ± 0.023 MPa, and a toughness of 3.860 ± 0.075 MJ m⁻³. In addition, the self-healing efficiency of the hydrogels is higher than 90% within 10 min at room temperature. Benefiting from the excellent self-healing properties, the shapeability of the hydrogel fragments is observed using different molds. In addition, the hydrogels display rapid pH-driven shape memory effects and can recover to their original shape within 260 s. Overall, this work provides a new approach to hydrogels with integrated excellent mechanical properties, self-healing abilities, and rapid pH-driven shape memory effects.     

GCr15SiMn轴承钢中大尺寸TiN生成与控制

 以西宁特钢EAF→LF→VD→IC工艺路线生产GCr15SiMn轴承钢为研究背景,采用矿物解离分析仪、夹杂物自动分析系统、化学分析及X射线荧光光谱仪等检测手段与热力学计算相结合的方法,研究了铸锭中大尺寸TiN夹杂物的析出机理,分析了冶炼阶段钢液中钛含量增加的原因,并提出了相应的改进工艺。通过对轴承钢中残余钛、氮含量的热力学计算,发现大尺寸TiN主要是在凝固过程中析出和长大,降低冶炼过程中钛含量是控制TiN生成的主要途径。对原工艺冶炼过程钛含量变化进行分析,钢液中钛增量主要发生在EAF出钢→LF结束阶段,其中52%钛增量来自于炉渣。为了避免炉渣中钛进入钢液,借助于七元炉渣CaO-SiO₂-MgO-FeO-Al₂O₃-MnO-TiO₂与钢液之间平衡的钛分配比(LTi)模型,计算了铝含量和炉渣中CaO含量对LTi 的影响,预测了最佳的平衡炉渣成分。结果表明,适当降低铝含量和炉渣中CaO含量可以提高渣-钢之间的钛分配比,降低钢液的钛含量;当铝质量分数为0.015%～0.025%、CaO质量分数为50%～55%时,其他炉渣组元的最佳成分(质量分数)为18%～24% Al₂O₃和12%～17% SiO₂。此外,定量描述了不同LTi条件下EAF下渣量与LF终点钛含量的关系。最后,采用“低炉渣碱度、低铝含量以及严格控制电炉下渣量”的改进措施进行了优化试验,优化后冶炼终点钛质量分数可控制在小于0.002 0%,铸锭TiN平均数密度可由原工艺的2.09个/mm2降低至0.73个/mm2,且TiN尺寸几乎都小于10 μm。     

电弧炉短流程冶炼石油套管钢中夹杂物的演变规律

为研究石油套管钢(34Mn6)中夹杂物的演变规律,对钙处理效果进行精准化控制,进行全流程取样分析,通过采用SEM-EDS分析夹杂物形貌和成分,同时结合Aspex夹杂物自动分析仪统计夹杂物的数量、成分和尺寸分布。研究结果表明,LF精炼具有较好的脱硫与脱氧能力;钙处理前,由于渣钢反应的进行,夹杂物数量明显减少,夹杂物成分中SiO₂含量增加;经过钙处理后,夹杂物成分发生显著变化,由MgO-Al₂O₃系转变为MgO-Al₂O₃-CaO系和SiO₂-Al₂O₃-CaO系,夹杂物形貌由尖角夹杂向球状夹杂过渡。在铸坯中,夹杂物数量减少,其成分已偏离液相区,向富CaO区域移动。对钙处理进行优化,通过利用热力学软件FactSage进行计算,得出钢液中钙的质量分数稳定在0.001 3%时对夹杂物的改性效果最佳,钢液中的夹杂物控制较好。     

FRECKLE FORMATION AND CHARACTERIZATION OF A Ni-Cr-Mo-Fe-W ALLOY

The freckle formation and their phase characterization in freckle areas were investigated by means of microstructure analysis approaches and a thermodynamic equilibrium phase calculation method in a Ni-Cr-Mo-Fe-W alloy. These results show that in freckle areas a large number of M6 C, u and P phases precipitate in grain boundaries even within grain due to the enrichment and segregation of Mo and C during solidification, which results in small grains in freckle areas. Equilibrium phase and liquid segregation calculation can give an reasonable interpretation of the freckle feature for this alloy.     

多元高铬铸铁在反击式破碎机板锤上的应用

在高铬铸铁中加入多种少量和微量合金元素用以生产反击式破碎机板锤，可使产品耐磨性和综合力学性能得到很大程度的改善。使用寿命比原用高锰钢提高4倍以上。     

Thermodynamic study of the phase equilibria in the Sn−Ti−Zn ternary system

The Sn−Ti−Zn ternary phase diagram has been constructed using the CALPHAD technique. The Ti−Zn binary system phase boundaries were determined using differential scanning calorimetry and the solid-liquid diffusion couples method. In addition, the formation energy of some stoichiometric compounds was obtained using first-principle band energy calculations. For the ternary system, some alloys were prepared by equilibration at 600 or 700 °C, and the compositions of the precipitates were analyzed using electron probe microanalysis. Thermodynamic assessment of the Ti−Zn and Sn−Ti−Zn systems was performed based on the experimental information and by adopting reported values of the thermodynamic properties of the Sn−Zn and Sn−Ti binary systems. Microstructural observation showed that Sn₃Ti₅Zn₁₂ exists in the ternary system. Seven types of invariant reaction on the Sn-rich liquidus surface of the ternary system are predicted by the phase diagram calculations. The ternary eutectic point falls at 0,0009 mass% Ti and 8.69 mass% Zn, at T=192.40°C, which is slightly lower than the calculated eutectic point of Sn−Zn binary alloy (T=192.41°C). Based on these results, a nonequilibrium solidification process using the Scheil model was simulated. This paper was presented at the International Symposium on User Aspects of Phase Diagrams, Materials Solutions Conference and Exposition, Columbus, Ohio, 18–20 October, 2004.     

Thermodynamic database of the phase diagrams in the Mg-Al-Zn-Y-Ce system

The Mg-Al-Zn-Y-Ce system is one of the key systems for designing high-strength Mg alloys. The purpose of the present article is to develop a thermodynamic database for the Mg-Al-Zn-Y-Ce multicomponent system to design Mg alloys using the calculation of phase diagrams （CALPHAD） method, where the Gibbs energies of solution phases such as liquid, fcc, bcc, and hcp phases were described by the subregular solution model, whereas those of all the compounds were described by the sublattice model. The thermodynamic parameters describing Gibbs energies of the different phases in this database were evaluated by fitting the experimental data for phase equilibria and thermodynamic properties. On the basis of this database, a lot of information concerning stable and metastable phase equilibria of isothermal and vertical sections, molar fractions of constituent phases, the liquidus projection, etc., can be predicted. This database is expected to play an important role in the design of Mg alloys.     

中小批量铸铁车间就地技术改造

采用相互兼顾的原则，进行中小批量的铸铁车间就地技术改造，较好地解决了工人劳动强度、作业环境、铸件质量、产量与技改投入的矛盾。     

形态对钯-氢体系热力学性质的影响

基于实验测定海绵Pd颗粒在278K-323K范围内吸放H2，D2的P-C-T曲线．结合文献给出的其它形态的Pd吸放氢结果进行系统比较分析．探讨了形态对钯-氢体系热力学性质的宏观影响和微观本质。在室温附近，氢的饱和固溶度与坪压随Pd的粒度减小而增加；Pd的形态或粒度对氢的饱和固溶度和吸氧坪压的影响程度刚随温度升高而减小，而且坪压之间的差别在温度较高时不再明显甚至消失。吸氘坪压差别大，解吸坪压差别小。Pd—H体系中α→β的相变热焓、热熵（绝计值)随粒度减小而减小，单晶Pd相应热力学函数最小。海绵Pd颗粒中的压力迟滞效应最明显．材料本底缺陷密度决定不同形态Pd-H体系的压力迟滞效应的大小。     

四异丁氧基镍酞菁的合成及其溶剂效应

4 异丁氧基邻苯二腈与氯化镍在强有机碱 1 ,8 二氮杂双环 (5 ,4,0 )十一碳烯 7催化下反应 ,合成了四异丁氧基镍酞菁 ,产物经FT -IR、元素分析、UV -Vis吸收光谱和1 H NMR表征了结构 ;并研究了其溶剂效应 ,结果表明 :最大吸收峰波数ν与函数 f(n ,ε)存在一定的线性关系 ,线性相关系数为 0 940 2 ,而Bayliss函数项 (n2 - 1 ) /(2n2 +1 )决定了最大吸收波长 (λmax)的位移变化 ;化合物的λmax在不同溶剂中随聚集程度增加 ,发生一定程度的蓝移