搪瓷用含钛热轧高强钢板的显微组织和力学性能研究

热水器搪瓷内胆具有使用寿命长、无毒无害以及高耐蚀等特点,得到了广泛的应用,可替代传统的不锈钢、热镀锌和塑料等材料制作的内胆。为了满足成型、焊接和涂搪等要求,制作搪瓷内胆的钢板必须具有高强度以及优良的成型性、焊接性和涂搪性。研究表明,含钛热轧高强钢中钛主要以碳化物和氮化物的形式存在,不仅具有优良的焊接性和涂搪性,在焊接过程中和高温烧成时由于钛的析出物能有效地抑制晶粒长大,保持较高的强度。通过优化碳、锰和钛等元素的匹配,开发了4个不同屈服强度级别(210 MPa,245 MPa,330 MPa和360 MPa)的热轧搪瓷钢板。     

Mechanical Properties of Weldbonded Joints of Advanced High Strength Steels

In lightweight car body shell mass production, due to requirements on vehicle weight reduction and carbon dioxide emissions, joining of advanced high strength steels (AHSS) with different joining procedures and especially hybrid bonding techniques is becoming more and more important. One of these hybrid bonding techniques is the combination of resistance spot welding and adhesive bonding called weldbonding. One of the important advantages of weldbonded joints in comparison to resistance spot welded joints are the enhanced mechanical properties. To guarantee sufficiently high quality conditions regarding the strength of the weldbonded joints, the influences of the applied adhesive systems and of different base metal combinations are studied. This is carried out for both non-corrosive and corrosive environments and for the choice of different joining parameters settings. In particular, the mechanical behaviour of the weldbonded joints is investigated under quasi-static, impact and fatigue loads. Furthermore, the energy absorption of the weldbonded joints for both non-corrosive and corrosive environments is studied. It is shown that the weldbonded joints possess higher mechanical strengths in all load cases (quasi-static, impact and fatigue). Corrosive attack affects weldbonded joints, and the quasi-static strength is reduced. Resistance spot welded joints are not affected by the corrosive attack, but even after several weeks of corrosive attack, the quasi-static strength of weldbonded joints remains higher than that of resistance spot welded joints.     

碳纳米管对硅灰/水泥砂浆力学和2D-3D微结构性能的影响(英文)

为了研究碳纳米管对硅灰/水泥砂浆力学性能及2D和3D微结构的影响。采用扫描电子显微镜测试了砂浆的2D空间形貌,并首次运用X射线计算机断层扫描技术对碳纳米管增强硅灰/水泥砂浆体系的3D缺陷进行了表征,同时探讨了砂浆28d龄期的断裂韧性和耐磨性等力学性能的变化规律。结果表明,碳纳米管显著提高了砂浆的断裂韧性和耐磨性,改善了基体的微观结构,硅灰的加入有利于碳纳米管在基体中的分散和增强效应的发挥。     

Effect of Initial α-Phase Content on Microstructure and Mechanical Properties of Sintered Silicon Carbide

By using α- and β-SiC starting powders with similar particle sizes, the effects of initial α-phase content on the microstructure and the mechanical properties of the liquid-phase-sintered and subsequently annealed materials were investigated. The microstructures developed were analyzed by image analysis. When β-SiC powder was used, the grains became elongated. The average diameter decreased with increasing α-SiC content and the aspect ratio showed a maximum at 10%α-SiC and decreased with increasing α-SiC content in the starting powder. Such results suggest that microstructure can be controlled by changing α-phase content in starting powders. The strength increased with increasing α-SiC content in the starting powder while the fracture toughness decreased with increasing α-SiC content. There may be a trade-off in improving both the strength and toughness in SiC ceramics sintered with oxide additives.     

活性催化树脂结合镁碳砖的微观结构与力学行为研究

介绍了以活性催化树脂为结合剂的镁碳砖的微观结构及其力学性质。通过对比实验发现：加入活性催化树脂的镁碳砖其结构与天然、鳞片状石墨相似,在工业应用与生态学方面有着卓越的动力学、热学和化学性能。     

Microstructure and Mechanical Properties of alpha-Silicon Carbide Sintered with Yttrium-Aluminum Garnet and Silica

The effect of glassy-phase chemistry, using Y₃Al₅O₁₂ (YAG) and SiO₂ as sintering additives, on the microstructure and mechanical properties of liquid-phase-sintered, and subsequently annealed, α-SiC materials was investigated. The microstructural development of annealed materials was insensitive to changes in glass chemistry. The mechanical properties vs SiO₂/YAG ratio curve had a maximum; i.e., there was a small glass composition range at which optimum mechanical properties were realized. The best results were obtained when the ratio was ∼0.5. The flexural strength and fracture toughness of the material were >450 MPa and >6 MPa·m^1/2, respectively.     

硅粉对硬化水泥浆体微结构的影响的研究进展

主要从3个方面阐述了硅粉对硬化水泥浆体微结构影响的研究进展.同时预测该项研究今后的发展方向.     

化学激发硅灰强化钢渣基胶凝材料的微观结构及力学性能

化学激发钢渣基胶凝材料的抗压强度低,难以满足建筑材料对强度的要求;通过掺入少量硅灰以加速其水化反应,改善化学激发钢渣基胶凝材料的力学性能.当碱激发剂Na2SiO3·9H2O用量11wt％,硅灰掺量10wt％时,碱激发硅灰-钢渣基胶凝材料在室温养护28 d后,其抗压强度达56.7 MPa,较不掺硅灰的胶凝材料强度提高了59.72％.XRD、SEM及MIP结果表明:钢渣在碱激发作用下,随龄期的延长,氢氧化钙量逐渐减少,无定形的水化产物增多,微观结构更加致密,加入硅灰后,最可几孔径明显减小,无害孔的数量明显增多,导致其强度大幅度提高.     

稀土Ce对X65管线钢组织和性能的影响

通过真空感应炉对X65管线钢进行重新冶炼,采用金相显微镜和扫描电镜进行组织观察,采用微机控制电子式万能实验机和电子式摆锤冲击实验机进行性能检测,研究了稀土Ce对X65管线钢的显微组织和力学性能的影响. 结果表明,稀土Ce的加入对钢液有明显的变质作用,使夹杂物变成球状的稀土化合物类夹杂并使晶粒细化,提高了X65管线钢的各项力学性能参数;不同热处理工艺表明,对于X65稀土管线钢,若采用860℃终轧温度并空冷,也能获得良好的力学性能.     

高分子共混物的相结构对力学性能的影响

本文以聚丙烯 尼龙1010(PP PA1010)共混体系为模型研究了高分子共混物的微观相结构对宏观力学性能的影响,并通过微观力学模型来预测共混物的拉伸强度。通过光散射试验和扫描电镜结果讨论了两相平均弦长比(L1 L2)以及分散相的质心相关距(D)与拉伸性能的关系。结果表明,当分散相一定时,拉伸强度随两相相对尺寸的增大和分散相颗粒相关性的减弱而减小。理论计算的分散相最小体积分数与相形貌观察的结果非常接近,添加增容剂的体系,由于改善了界面粘合,使理论预测值与试验结果很好的吻合。     

丙烯腈含量对氢化丁腈橡胶耐油和耐低温性能的影响

选取4种不同丙烯腈含量的氢化丁腈橡胶（HNBR）,研究丙烯腈含量对HNBR耐油性能和耐低温性能的影响。结果表明,随着丙烯腈含量的增大,HNBR硫化胶的拉伸强度和撕裂强度增大,4069液压油浸泡和热空气老化后的压缩永久变形增大,玻璃化温度和低温回缩10%的温度升高,-45℃压缩耐寒因数减小,耐低温性能变差。     

Effect of Processing on Microstructure and Mechanical Behavior of Magnesium Oxide

Polycrystalline MgO specimens were fabricated from two powders by hot-pressing in graphite or alumina dies and annealing in air, in vacuum, or within the graphite die in vacuum. Parameters affected were density, grain size, and visual appearance, which was considered to be dependent on grain boundary structure. The formation of a boundary liquid phase with one type of powder tended to eliminate the effect of the processing variables. The character (microstructure) of the specimens was correlated with their mechanical behavior in compression at a constant strain rate at 1200°C.     

热疲劳作用对混凝土力学性能及微观结构的影响

我国西北地区日、年温差大,混凝土经历着温差产生的热疲劳劣化。保持环境湿度恒定,在20 ℃、30 ℃、40 ℃温差下开展两种强度等级的混凝土热疲劳试验,测定其抗压强度、劈裂抗拉强度等宏观性能变化规律;通过超声无损检测技术和压汞试验测定微观结构。结果表明:热疲劳劣化效应明显,随循环温差的增大和循环次数增加,混凝土强度下降明显,C40混凝土下降幅度大于C25混凝土,且劈裂抗拉强度较抗压强度对热疲劳作用更敏感;超声波速呈减小趋势,说明混凝土内部裂隙缺陷增多;同一循环温差下,混凝土的孔隙率、孔隙总体积、平均孔径、中值孔径、最可几孔径随温差循环次数增加而增大,孔隙总表面积减小,孔隙结构表现出粗化的特征且呈劣化的趋势,C40混凝土的孔隙率小于C25混凝土,但其孔隙率相对变化值更大,从微观层面揭示了混凝土在热疲劳作用下强度损伤的内在原因。     

先进复合材料在汽车领域的应用

介绍了先进复合材料在汽车的应用、用材体系和制造工艺的选择、以及最新的应用动态.指出减轻汽车质量,从而节省燃油,减少排放对环境的污染.同时指出了先进复合材料在汽车应用上的技术研发要点和目前存在的问题,最后结合我国的具体情况提出了相关的发展建议.     

Microstructure and Mechanical Properties of Friction Stir Welded SiC/TiB2 Reinforced Aluminum Hybrid Composites

Silicon - In the recent decades, the use of aluminum alloy has significantly enhanced especially in engineering applications extensively used in shipbuilding, aircraft, structural and automobile...     

硅灰和石灰石粉对MKPC浆体力学性能的影响

为了研究硅灰和石灰石粉对MKPC水泥浆体力学性能的影响,采用水浸泡和自然养护的方法,测试了参考样、单掺硅灰和石灰石粉以及双掺硅灰和石灰石粉等不同矿物掺合料对MKPC基材料硬化体的力学性能的影响.结果 表明:掺入矿物掺合料可以改善MKPC基材料浆体的质量损失;其中,以双掺矿物掺合料MKPC基材料浆体的性能为最佳,同时,研究还发现MKPC硬化体试块的抗压强度无论在何种养护条件下,掺入矿物掺合料的MKPC硬化体的抗压强度较未掺入任何矿物掺合料的抗压强度得到很好的改善,尤其以双掺硅灰和石灰石粉的MKPC硬化体的强度改善最佳.     

TEGDN含量和NC含氮量对TEGDN/NG混合酯双基推进剂力学性能的影响

采用无溶剂法制备了24种不同硝化三乙二醇(TEGDN)含量、不同NC含氮量的双基推进剂样品,并测试了其高温(50℃)、常温(20℃)和低温(-40℃)下的力学性能;讨论了TEGDN含量和NC含氮量对双基推进剂力学性能的影响。结果表明,混合酯双基推进剂的高温和常温抗拉强度随TEGDN含量增加而逐渐下降,在TEGDN质量分数较低(≤7.7%)时,随NC含氮量的升高呈降低趋势,在TEGDN质量分数较高(≥15.4%)时,随NC含氮量的升高呈先上升后下降的趋势;低温抗拉强度随TEGDN含量增加而逐渐升高,随NC含氮量的升高逐渐降低;高温、常温、低温下的断裂延伸率均随TEGDN含量增加逐渐上升,随NC含氮量的升高逐渐下降;提高TEGDN含量可以改善NC的塑化性能,但含氮量12.6%及以上的NC不易被良好塑化。     

粉煤灰掺量对再生混凝土力学性能和抗冻性的影响研究

研究粉煤灰掺量、再生粗骨料取代率对再生混凝土抗压强度和抗折强度的影响,并对再生混凝土在不同冻融循环次数下的抗压强度和质量损失率进行了研究.结果表明:随着粉煤灰掺量的增加,再生混凝土抗压强度呈先增大后降低的趋势,当粉煤灰掺量为15%,再生粗骨料取代率为30%时,再生混凝土的抗压强度达到最大;粉煤灰掺量对抗折强度提高幅度较小;在冻融循环低于50次时,试块抗压强度下降速度较缓,此后下降速度加快,当冻融循环达到150次时,强度损失最大;再生粗骨料取代率对试块的抗冻性影响高于粉煤灰掺量.建立了考虑再生粗骨料取代率、粉煤灰掺量因素的冻融循环作用下再生混凝土抗压强度指数衰减规律预测模型.     

硅溶胶对无机磷酸铝涂料防腐性能的影响

采用化学合成法制备磷酸铝粘结剂,以球形铝粉为骨料,添加不同含量的硅溶胶,制备磷酸铝涂料,再经过热处理制备磷酸铝涂层。通过X射线衍射分析(XRD)表征粘结剂和涂层物相结构,采用扫描电子显微镜(SEM)表征涂层形貌,通过电化学测试和浸泡试验对比研究涂层腐蚀行为。分析结果表明:在磷酸铝涂层中添加适量硅溶胶可以改善涂层表面质量和耐腐蚀性能,从而使涂层腐蚀电位升高,腐蚀电流降低,阻抗值增大。添加10%硅溶胶的涂层质量最佳,耐腐蚀性能最优。