Investigation of the Dilation of Epoxy with Negative Thermal Expansion Fillers

2010 ◽  
Vol 44-47 ◽  
pp. 2950-2953
Author(s):  
Sheng Yi Chang ◽  
Hsi Hsun Tsai ◽  
Sheng Ching Wang
Keyword(s):  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Ceramic Powder ◽  
Negative Thermal Expansion ◽  
Negative Coefficient ◽  
Silica Powder ◽  
Silica Filler ◽  
The One ◽  
Silicon Based ◽  
Electronic Elements

The bonding glue is well used in packaging of the opto-electronic elements. The light paths of the elements are aligned accurately before bonding, the coefficient of thermal expansion of bonding glue is much more large than the one of silicon based optoelectronic elements, the light paths of the elements are thus misalignment after the bonding. The silica filler is usually mixed into the bonding glue for lowering the coefficient of thermal expansion. In this paper, the ceramic powder of the ZrW2O8 with negative coefficient of thermal expansion is thus mixed the commercial bonding glue for deriving of the extra low dilation adhesion. The thermal expansion of the composite bonding glue with negative coefficient of thermal expansion fillers is measured accurately to compare with the filler of silica powder. The results show that a composite glue with the very low coefficient of thermal expansion is therefore acquired for packaging of optoelectronic elements.

Size and crystal symmetry breaking effects on negative thermal expansion in ScF3 nanostructures

2021 ◽  
Author(s):  
Chunyan Wang ◽  
Dahu Chang ◽  
Junfei Wang ◽  
Qilong Gao ◽  
Yinuo Zhang ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Symmetry Breaking ◽  
Coefficient Of Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Crystal Symmetry ◽  
Negative Coefficient ◽  
Membrane Vibration

New membrane vibration and surface symmetry breaking effects determine the negative coefficient of thermal expansion at the nanoscale.

Experimentally Investigation of Curing Shrinkage of Extra Low Dilated Epoxy by Fiber Bragg Gratings

2010 ◽  
Vol 44-47 ◽  
pp. 2958-2962
Author(s):  
Chun Der Cheng ◽  
Hsi Hsun Tsai ◽  
Hui Ping Feng
Keyword(s):  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Axial Stress ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Temperature Cycle ◽  
Central Wavelength ◽  
Silica Filler ◽  
Curing Shrinkage ◽  
On Line

The bonding adhesion with low shrinkage and coefficient of thermal expansion is really important for packaging of the photonic and optoelectronic elements. Lots of the thermoset glue is thus developed for this packaging. however, the curing shrinkage of the adhesion is relatively large. The silica filler is usually mixed into the epoxy for lowering the curing shrinkage and the CTE. In this study, the filler with negative CTE is derived to decrease the CTE and shrinkage of the composite epoxy. The fiber Bragg gratings is built in the composite of epoxy/filler. The adhesive composite is then put into the temperature cycle chamber for curing. At the meanwhile the FBGs during curing is on-line monitored by the Optical Oscillation Analyzer. Measuring the variation of the central wavelength of FBGs, the curing shrinkage of the composite epoxy with NCTE filler can be is derived. The results show that axial stress is increased drastically during the chemical curing stage. By application of this NCTE filler/epoxy adhesion, the property of the lower shrinkage is expected.

scholarly journals A Proposal for a Composite with Temperature-Independent Thermophysical Properties: HfV2–HfV2O7

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5021
Author(s):  
Philipp Keuter ◽  
Anna L. Ravensburg ◽  
Marcus Hans ◽  
Soheil Karimi Aghda ◽  
Damian M. Holzapfel ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Temperature Coefficient ◽  
Thermophysical Properties ◽  
Coefficient Of Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Phase Fraction ◽  
Formation Temperature ◽  
Oxygen Mobility ◽  
Zero Temperature ◽  
Coefficient Of Elasticity

The HfV2–HfV2O7 composite is proposed as a material with potentially temperature-independent thermophysical properties due to the combination of anomalously increasing thermoelastic constants of HfV2 with the negative thermal expansion of HfV2O7. Based on literature data, the coexistence of both a near-zero temperature coefficient of elasticity and a coefficient of thermal expansion is suggested for a composite with a phase fraction of approximately 30 vol.% HfV2 and 70 vol.% HfV2O7. To produce HfV2–HfV2O7 composites, two synthesis pathways were investigated: (1) annealing of sputtered HfV2 films in air to form HfV2O7 oxide on the surface and (2) sputtering of HfV2O7/HfV2 bilayers. The high oxygen mobility in HfV2 is suggested to inhibit the formation of crystalline HfV2–HfV2O7 composites by annealing HfV2 in air due to oxygen-incorporation-induced amorphization of HfV2. Reducing the formation temperature of crystalline HfV2O7 from 550 °C, as obtained upon annealing, to 300 °C using reactive sputtering enables the synthesis of crystalline bilayered HfV2–HfV2O7.

Very high or close to zero thermal expansion by the variation of the Sr/Ba ratio in Ba1−xSrxZn2Si2O7 – solid solutions

2016 ◽  
Vol 45 (11) ◽  
pp. 4888-4895 ◽  
Author(s):  
Christian Thieme ◽  
Christian Rüssel
Keyword(s):  
Thermal Expansion ◽  
Solid Solutions ◽  
Coefficient Of Thermal Expansion ◽  
Positive Coefficient ◽  
Negative Coefficient ◽  
Very High

The compound BaZn2Si2O7 shows a highly positive coefficient of thermal expansion, while replacement of more than 10% of Ba2+ by Sr2+ results in a negative coefficient of thermal expansion.

Rheological and Thermomechanical Properties of Meso and Non-Porous Silica Filled Epoxy Composites

2015 ◽  
Vol 815 ◽  
pp. 67-71
Author(s):  
Gang Li ◽  
Peng Li Zhu ◽  
Tao Zhao ◽  
Rong Sun ◽  
Daniel Lu
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Glass Transition ◽  
Mesoporous Silica ◽  
Coefficient Of Thermal Expansion ◽  
Porous Silica ◽  
Thermomechanical Properties ◽  
Epoxy Composites ◽  
Silica Microspheres ◽  
Silica Filler

In the present study, epoxy based composite filled with meso and non-porous silica microspheres with similar size were prepared respectively and their rheological and thermo-mechanical properties were studied systematically. The results showed that the mesoporous silica/epoxy composites showed much higher viscosity, storage modulus and glass transition temperature (Tg) while lower coefficient of thermal expansion (CTE) than did epoxy composites with nonporous silica particles, which could be attributed to the stronger interface interaction between the mesoporous silica filler with larger specific surface area (BET) and the epoxy matrix.

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