对羟基苯甲酸对HDPE结晶行为及力学性能的影响

采用DSC研究了对羟基苯甲酸(HBA)对高密度聚乙烯(HDPE)非等温结晶行为的影响。分析了HBA的引入对HDPE的结晶行为、晶片厚度分布、结晶度以及力学性能的影响。结果表明，当HBA用量为HDPE的0．5％-1．0％时可以促进HDPE的结晶，从而加快HDPE的结晶速度，提高HDPE的结晶度，降低片晶的平均厚度及其分布，并提高其力学性能。     

层状液晶乳液的缓释效应

重点讨论了层状液晶乳液体系在应用到衣物柔顺剂中时其乳液结构及油相的极性对提高挥发性物质长久保留功效的影响。采用固相微萃取和气相色谱/质谱的分析技术,测定了顶空中挥发性物质的浓度随时间的变化,结果发现由聚氧乙烯醚失水山梨醇脂肪酸酯、失水山梨醇脂肪酸酯、长链脂肪醇、油和水组成的水包油型球形洋葱状层状液晶乳液LO1相和水包油型球形洋葱状LO1与平面层状Lβ的混合两相在应用过程中能够最有效地延缓具有低极性的挥发性物质的释放平衡,相反油包水型球形洋葱状层状液晶LO2和平面层状液晶Lβ不能有效地提高挥发性物质任何阶段中在织物上的沉积和保留。     

A comprehensive sintering mechanism for TBCs‐Part I: An overall evolution with two‐stage kinetics

A comprehensive sintering mechanism for lamellar thermal barrier coatings was reported experimentally and theoretically in this study. To begin with, an overall property evolution with two‐stage kinetics was presented during thermal exposure. The increase in mechanical property at initial thermal exposure duration (stage‐I) was much faster with respect to that in the following longer duration (stage‐II). At the stage‐I, the in situ pore healing behavior revealed that the significant faster sintering kinetics was attributed to the rapid healing induced by multipoint connection at the intersplat pore tips, as well as a small quantity of the narrow intrasplat cracks. At the following stage‐II, the residual wide intersplat pore parts and the wide intrasplat cracks decreased the possibility of multiconnection at their counter‐surfaces, resulting in a much lower sintering kinetic. Moreover, a structural model based on the microstructure of plasma sprayed YSZ coatings was developed to correlate the microstructural evolution with mechanical property. Consequently, the model predicted a two‐stage evolutionary trend of mechanical property, which is well consistent with experiments. In brief, by revealing the pore healing behavior, this comprehensive sintering mechanism shed light to the structure tailoring toward the advanced TBCs with both higher thermal‐insulating effect and longer life time.     

双相γ+α2钛合金片层承载力的数学模型及预测

为了研究双相γ+α2钛合金晶体中片层组织的承载特性,建立了相应晶体不同取向力学性能的数学模型,并计算了γ相及γ+α2片层组织不同取向的承载力.通过对模型的数值求解,得到γ相和γ+α2片层组织的承载力随不同加载方向的变化规律.计算结果表明:随着α2相体积分数的增加,γ+α2片层组织的最大承载力方向逐渐趋向平行于α2相的(0001)面,临界α2相等价体积分数为λe=30%.这从理论上解释了γ+α2片层组织的最大承载力方向为平行于α2相的(0001)面这一传统观点.这一结论成立的条件为α2相等价体积分数λe>30%.     

A COMPONENT-SPECIFIC ALLOY DESIGN OF TiAl INTERMETALLICS

ＡＣＯＭＰＯＮＥＮＴ－ＳＰＥＣＩＦＩＣＡＬＬＯＹＤＥＳＩＧＮＯＦＴｉＡｌＩＮＴＥＲＭＥＴＡＬＬＩＣＳＪ．Ｚｈａｎｇ;Ｄ．Ｘ．Ｚｏｕ;Ｚ．Ｚ．ＺｈａｎｇａｎｄＺ．ＹＺｈｏｎｇ（ＣｅｎｔｒａｌＩｒｏｎ＆ＳｔｅｅｌＲｅｓｅａｒｃｈＩｎｓｔｉｔｕｔｅ,Ｂｅｉ...     

INFLUENCE OF TWINNING AND DISLOCATION GLIDE DURING CREEP OF EQUIAXED AND LAMELLAR TiAl ALLOYS

１　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｃｒｅｅｐｒｅｓｉｓｔａｎｃｅｏｆｔｗｏｐｈａｓｅｔｉｔａｎｉｕｍａｌｕｍｉｎｉｄｅａｌｌｏｙｓｈａｓｂｅｅｎｃｏｎｆｉｒｍｅｄｔｏｄｅｐｅｎｄｎｏｔｏｎｌｙｏｎｌａｍｅｌｌａｒｖｏｌｕｍｅｆｒａｃｔｉｏｎｏｒｇｒａｉｎｓｉｚｅｂｕｔａｌｓｏｏｎｏｔｈｅｒｐａｒａｍｅｔｅｒｓｓｕｃｈａｓｔｈｅｍｏｒｐｈｏｌｏｇｙｏｆｅａｃｈｐｈａｓｅ［１－４］．Ｔｈｅｐｒｅｓｅｎｃｅｏｆｌａｍｅｌｌａｒｉｎｔｅｒｆａｃｅｓｌｅａｄｓｔｏｉｍｐｒｏｖｅｄｃｒｅｅｐｒｅｓｉｓ…     

Zn-Cu包晶系中的片层状类共晶组织

采用Ｂｒｉｄｇｍａｎ定向凝固法研究了不同生长速度下Ｚｎ－３．３７％Ｃｕ（质量分数）包晶合金的凝固过程及其组织形态．当生长速度高于１．０ｍｍ／ｓ时,出现片层状类共晶生长,且片层间距和生长速度的关系很好地符合λｖ１／２＝（２１６±４２）μｍ３／２·ｓ－１／２关系,该数值与多数共晶系相比偏高．这类共晶组织在包晶合金中的发现有助于对包晶合金凝固过程的进一步研究．     

γ-TiAl合金中片层组织取向的控制

γ-TiAl合金是应用前景广泛的轻质高温结构材料,其全片层组织性能具有明显的各向异性.籽晶法定向凝固利用具有特定片层取向的籽晶材料使高温α相沿<110>方向生长,获得与生长方向平行的定向全片层组织;改变凝固路径法则通过在凝固组织中获得全β相生长,使最终片层组织与生长方向呈0o和45o夹角.本文综述了两种方法控制TiAl合金片层取向的原理及其研究进展,讨论了合金成分、凝固参数对片层取向控制过程的影响.针对国内外γ-TiAl合金定向全片层组织制备的现状,提出了需要进一步研究的问题.     

Lamellar structure and properties in poly(ethylene terephthalate) fibers

The fibrillar and the lamellar structures in a range of poly(ethylene terephthalate) fibers were studied by small-angle X-ray scattering. The intensity maxima in the lamellar peaks lie on a curve that can be described as an ellipse. Therefore, the two-dimensional images were analyzed in elliptical coordinates. The dimensions of the coherently diffracting lamellar stack, the dimensions of the fibrils, the interfibrillar spacing, and the orientation of the lamellar surfaces were measured in addition to the lamellar spacing. The orientation of the lamellar planes and the size of the lamellar stacks had a better correlation with mechanical properties of the fibers than did the lamellar spacing. In particular, longer and wider lamellar stacks reduced fiber shrinkage, as did the closer alignment of the lamellar normal to the fiber axis. These structural features were also associated with lower tenacity. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2527–2538, 1998     

变形终止温度对GCr15轴承钢显微组织的影响

采用MMS300热模拟试验机对GCr15轴承钢的热变形工艺进行模拟,研究变形终止温度对其显微组织的影响。结果表明,变形终止温度在770~870℃内变化时,其显微组织均为片层状珠光体+沿晶界分布的先共析碳化物,并且先共析碳化物周围存在铁素体薄膜。随着变形终止温度的升高,晶粒尺寸和珠光体团的尺寸均增加,珠光体的片层间距略微减小,硬度增加。通过回归分析获得维氏硬度与片层间距倒数的拟合方程HV=38.3S-1+92.7。变形终止温度在810~870℃内升高时,碳化物的网状程度增加。与810℃相比,变形终止温度为770℃和790℃时,碳化物的网状程度较严重。