Magnitude Of Thermal Expansion Research Articles

Insulated, Passivated & Adhesively-Promoted Bond Wire Using All-in-One Al2O3 Coating

Insulated, Passivated & Adhesively-Promoted Bond Wire Using All-in-One Al2O3 Coating

Contribution of thermal expansion on gas adsorption to coal sorption-induced swelling

Adsorption of gases such as methane and carbon dioxide in coal is an exothermic process. Under isentropic conditions (fully insulated condition), the ejected heat results in an additive transient thermal expansion in addition to the sorption-induced swelling. The magnitude of thermal expansion and its feedback on methane adsorption remains ill-defined. We explore this response in high volatile bituminous coal by measuring the exothermal release of heat (integral heat of adsorption) via temperature change during methane adsorption and use these calorimetric data to define the thermodynamic response. These data link thermal expansion directly to adsorption and adsorption swelling. The results show that methane adsorption can lead to the elevation of coal temperature by more than 10 °C. The resulting thermal expansion is consistent with adsorption swelling and related to adsorption capacity and pressure. The decline of surface potential energy resulting from adsorption is usually considered to be the reason for adsorption swelling. However, the results of this study show that thermal expansion due to the heat of adsorption may account for up to 35% of the total adsorption strain under ideal isentropic conditions. In non-isentropic laboratory experiments of adsorption swelling (approaching isothermal conditions), thermal expansion during adsorption cannot be measured accurately due to the rapid heat loss. However, in-situ within coalbed reservoirs, reduced heat dissipation may retain thermal deformation for longer and impact short-term permeability evolution.

ЗАСТОСУВАННЯ ПРОГРАМНОГО КОМПЛЕКСУ ANSYS CFX ДЛЯ МОДЕЛЮВАННЯ РУХУ ГАЗОВОГО ПОТОКУ В РЕАКЦІЙНОЇ КАМЕРІ ПРИ ОТРИМАННЯ СОРБЕНТУ НА ОСНОВІ ТЕРМОРОЗЩЕПЛЕНОГО ГРАФІТУ

Робота присвячена дослідженню можливостей використання методів чисельної газодинаміки для оптимізації і оцінки впливу конструктивних характеристик реакційної камери для отримання терморозщепленого графіту, як сорбенту для ліквідації наслідків розливу нафтопродуктів на водній поверхні, на його експлуатаційні характеристики. При розрахунках використовувалася стандартна SST модель турбулентної в'язкості реалізованості в програмному комплексі ANSYS 12. Результати моделювання дозволили домогтися стійкої роботи ежектора, за допомогою якого графіт вводиться в реакційну камеру. Виявлена необхідність перепрофілювання реакційної камери для забезпечення більш стійкого вихрового течії всередині її, з метою забезпечення сепарації розщепленого і нерозщепленного графіту, збільшення часу проходження реакції розширення і створення рівномірного теплового поля в реакторі, що дозволило зменшити щільність і підвищити сорбційну здатність терморасширенного графіту.

Phase stability and thermal expansion behavior of Cu6Sn5 intermetallics doped with Zn, Au and In

Cu6Sn5 is a critical intermetallic compound in future three-dimensional integrated circuit (3D IC) in micro-electronic packaging and has different crystal structures in the solid state. This paper investigates the effect of Zn, Au and In on the phase stability and thermal expansion behavior of Cu6Sn5 intermetallics over the temperature range of −80 °C to 240 °C, using in-situ variable temperature synchrotron powder X-ray diffraction (PXRD), dilatometry and first principles calculations. The results show Zn, Au and In stabilize the equilibrium high temperature hexagonal Cu6Sn5 crystal variant in directly alloyed samples, over the entire range of temperatures investigated. When present in hexagonal Cu6Sn5, Zn, Au and In atoms preferentially occupied specific Cu or Sn sites as leading to a more thermodynamically stable phase. The stabilization effect of Zn, Au and In was confirmed using PXRD, dilatometry and first principles calculations. The magnitude of thermal expansion and coefficients of thermal expansion (CTEs) were characterized for each addition. The stabilization of the hexagonal Cu6Sn5 structure prevented the discontinuity in volume expansion that occurs with the polymorphic transformation.

Thermal and Autogenous Shrinkages of Very Early Strength Latex-Modified Concrete

A study evaluated the factors influencing thermal and autogenous shrinkages of very early strength latex-modified concrete (VES-LMC) with respect to latex content (latex solids-cement ratio, by weight); water-cement ratio; retarder content (retarder solids-cement ratio, by weight); and antifoamer content (antifoamer-latex solids ratio, by weight). Examined were three levels of latex content (0%, 5%, 15%) at a constant slump, three levels of water-cement ratio (0.34, 0.38, 0.42) at a constant latex content of 15%, three levels of retarder content (0.0%, 0.3%, 0.6%), and three levels of antifoamer content (0.0%, 0.5% and 1.0%) at a constant latex content and water-cement ratio. Results were that total shrinkage was governed by thermal deformation at very early age because of the high heat of hydration of VES cement. After 5 h, total shrinkage was governed by the autogenous shrinkage process. The absolute magnitude of thermal expansion was 130 micro strains while the autogenous shrinkage was 120 micro strains. The autogenous shrinkage increased as latex content increased. VES-LM concrete with a high latex content and low water-cement ratio caused autogenous shrinkage. The total and autogenous shrinkages of VES-LMC were not affected or only slightly affected by the water-cement ratio or the antifoamer content. Excessive retarder induced expansion at very early age, which increased the absolute shrinkage. Thus, attention should be paid whenever retarder is added in response to weather conditions. Furthermore, immediate and proper wet curing is necessary when adding more retarder because of greater susceptibility to plastic shrinkage.