The changes of mechanical properties of epoxy/mica insulation materials in aging process

2002 ◽  
Author(s):  
Yanpeng Hao ◽  
Zhidong Jia ◽  
Xiongwei Jiang ◽  
Naikui Gao ◽  
Hengkun Xie
Keyword(s):  
Mechanical Properties ◽  
Aging Process ◽  
Insulation Materials

Sunlight exposure: the effects on the performance of paragliding fabric

2018 ◽  
Vol 69 (05) ◽  
pp. 381-389
Author(s):  
MENGÜÇ GAMZE SÜPÜREN ◽  
TEMEL EMRAH ◽  
BOZDOĞAN FARUK
Keyword(s):  
Mechanical Properties ◽  
Aging Process ◽  
Air Permeability ◽  
Sunlight Exposure ◽  
Test Results ◽  
Coating Materials ◽  
Strength Tests ◽  
Before And After ◽  
The Relationship ◽  
Dark Blue

This study was designed to explore the relationship between sunlight exposure and the mechanical properties of paragliding fabrics which have different colors, densities, yarn counts, and coating materials. This study exposed 5 different colors of paragliding fabrics (red, turquoise, dark blue, orange, and white) to intense sunlight for 150 hours during the summer from 9:00 a.m. to 3:00 p.m. for 5 days a week for 5 weeks. Before and after the UV radiation aging process, the air permeability, tensile strength, tear strength, and bursting strength tests were performed. Test results were also evaluated using statistical methods. According to the results, the fading of the turquoise fabric was found to be the highest among the studied fabrics. It was determined that there is a significant decrease in the mechanical properties of the fabrics after sunlight exposure. After aging, the fabrics become considerably weaker in the case of mechanical properties due to the degradation in both the dyestuff and macromolecular structure of the fiber

Effects on the microstructure and mechanical properties of Sn-0.7Cu lead-free solder with the addition of a small amount of magnesium

2016 ◽  
Vol 23 (6) ◽  
pp. 641-647
Author(s):  
Her-Yueh Huang ◽  
Chung-Wei Yang ◽  
Yu-Chang Peng
Keyword(s):  
Mechanical Properties ◽  
Aging Process ◽  
Intermetallic Layer ◽  
Eutectic Structure ◽  
Contact Angles ◽  
Solidification Structure ◽  
Lead Free Solder ◽  
Bulk Alloy ◽  
Scanning Calorimetry ◽  
Free Solder

AbstractThe influence of a small amount of magnesium (only 0.01 wt.%) added to the Sn-0.7Cu solder alloy during the aging process of microstructural evolution is studied along with the mechanical properties of the alloy. The experimental results indicate that the addition of magnesium decreases the tensile strength of the solders but improves their elongation. The solidification structure of eutectic Sn-0.7Cu consists of β-Sn, and the eutectic structure, which has extremely fine intermetallic nodules, Cu6Sn5, is located in the interdendritic region. When the magnesium is added to the Sn-0.7Cu alloy, the Sn dendrites become slightly coarser; in comparison, the melting point of the Sn-0.7Cu-0.01Mg alloy decreased by 2°C for the differential scanning calorimetry results of bulk alloy samples. Sn-0.7Cu-0.01Mg exhibits the lowest contact angles and the widest spreading areas. After aging, the Sn-0.7Cu and Sn-0.7Cu-0.01Mg solders show significant changes in strength, mainly because of the obvious increase in the thickness of the Cu6Sn5 intermetallic layer.

Hardening of Aged Duplex Stainless Steels by Spinodal Decomposition

2004 ◽  
Vol 10 (3) ◽  
pp. 349-354 ◽  
Author(s):  
F. Danoix ◽  
P. Auger ◽  
D. Blavette
Keyword(s):  
Mechanical Properties ◽  
Impact Toughness ◽  
Spinodal Decomposition ◽  
Stainless Steels ◽  
Aging Process ◽  
Atom Probe ◽  
Duplex Stainless Steels ◽  
Detailed Knowledge ◽  
Iron Chromium

Mechanical properties, such as hardness and impact toughness, of ferrite-containing stainless steels are greatly affected by long-term aging at intermediate temperatures. It is known that the α-α′ spinodal decomposition occurring in the iron–chromium-based ferrite is responsible for this aging susceptibility. This decomposition can be characterized unambiguously by atom probe analysis, allowing comparison both with the existing theories of spinodal decomposition and the evolution of some mechanical properties. It is then possible to predict the evolution of hardness of industrial components during service, based on the detailed knowledge of the involved aging process.

Investigation on the Stress Relaxation Aging Behavior of 2195 Al-Li Alloy

2021 ◽  
Vol 315 ◽  
pp. 37-42
Author(s):  
Hai Long Liao ◽  
Li Hua Zhan ◽  
Yuan Gao ◽  
Xue Ying Chen ◽  
Ming Hui Huang
Keyword(s):  
Mechanical Properties ◽  
Stress Relaxation ◽  
High Performance ◽  
Aging Process ◽  
Artificial Aging ◽  
Ageing Time ◽  
High Strength ◽  
Aging Behavior ◽  
Stress Corrosion Resistance ◽  
Scanning Electron

2195 Al-Li alloy is famous for high strength, excellent fatigue strength and good stress corrosion resistance, which is widely used in the manufacture of high-performance aerospace components. The aim of this study is to validate how the stress relaxation aging behavior effect on the mechanical properties of 2195 Al-Li alloy. Through mechanical property test, the research was found that the performance after stress relaxation aging is higher than artificial aging (AA). In addition, the analysis of scanning electron microscopy SEM and TEM revealed that dislocations should be introduced by the stress relaxation aging process, which is more conducive to the precipitation of the T1 phase and strengthened the material with prolong ageing time. The results show that stress relaxation aging can significantly promote the precipitation of the T1. Therefore, this paper sheds new light on how SRA can improve mechanical properties and that SRA make better improve the distribution of precipitates in the grain boundary.

Effect of the aging process and pre-deformation on the precipitated phase and mechanical properties of 2195 Al–Li alloy

2021 ◽  
pp. 142394
Author(s):  
Bingxin Xie ◽  
Liang Huang ◽  
Jiahui Xu ◽  
Hongliang Su ◽  
Huiping Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aging Process ◽  
Precipitated Phase

scholarly journals Effects of Pre-Stretching on Creep Behavior, Mechanical Property and Microstructure in Creep Aging of Al-Cu-Li Alloy

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 333 ◽  
Author(s):  
Jin Zhang ◽  
Zhen Jiang ◽  
Fushun Xu ◽  
Mingan Chen
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Dislocation Density ◽  
Creep Behavior ◽  
Aging Process ◽  
Artificial Aging ◽  
Dislocation Motion ◽  
Nucleation And Growth ◽  
Blocking Effect ◽  
Creep Stage

The effects of pre-stretching on creep behavior, mechanical properties and microstructure during the creep aging process of Al-Cu-Li alloy were investigated. AA2195 was taken as the representative of Al-Cu-Li alloys. It is found that the total creep strain and strength property of creep aged AA2195 specimens can be improved through effective pre-stretching. Unlike with artificial aging, yield strength increased increasing by 47%. The TEM images show that the constitution of aging precipitates in the creep-aged specimens are obviously changed by pre-stretching. Precipitates in the 2% pre-stretched specimen are mainly composed of T1 phase, while a great amount of θ’ phase accompanied with a few T1 phase were found in the non-pre-stretched specimen. Moreover, pre-stretching introduces many dislocations which benefit the creep deformation, but the increasing dislocation density also accelerates the nucleation and growth of the precipitates as well. The premature T1 phase has a great blocking effect to the dislocation motion, creating a lower decrease rate but a longer duration in the early creep stage. Except for the initial dislocations, the dislocation motion in the creep aging process is also a favorable factor to precipitate the T1 phase.

Weldability of pipe grade polyethylenes as realized from thermal and mechanical properties assessments

2016 ◽  
Vol 36 (8) ◽  
pp. 853-860 ◽  
Author(s):  
Vahabodin Goodarzi ◽  
Zahed Ahmadi ◽  
Mohammad Reza Saeb ◽  
Farkhondeh Hemmati ◽  
Mehdi Ghaffari ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Analysis ◽  
Molecular Weight ◽  
Aging Process ◽  
Pipe Production ◽  
Lamellar Thickness ◽  
Thermal And Mechanical Properties ◽  
Scanning Calorimetry ◽  
Injection Molded ◽  
The One

Abstract Since polyethylene (PE) has been widely accepted for the production of high-pressure fluid conveying pipelines, studies devoted to weldability of PE connections were always of major importance. In this study, two industrial PE grades designed for pipe production, namely PE80 and PE100, were injection molded, cut, and then welded as PE100-PE100, PE100-PE80, and PE80-PE80. The heat-welded joints were assessed by differential scanning calorimetry and tensile measurements. The results obtained from thermal and mechanical analyses were compared with equivalents for aged samples. Thermal analysis revealed that the melting point of the PE100-PE100 sample is obviously larger than the one for the PE80-PE80 joint, for the PE80 chains deteriorate the crystallization of PE100. Further, the PE80-PE80 sample showed the lowest lamellar thickness and crystalline molecular weight among the studied joints. The aging process was found to increase lamellar thickness and molecular weight, though in the PE100-PE100 sample such quantities very limitedly increased. The yield stress of aged joints was higher than that for just-prepared samples, while an inverse trend was seen for strain at break. From a practical viewpoint, the PE100-PE100 welds offer better properties.

scholarly journals Residual Flexural Performance of Epoxy Polymer Concrete under Hygrothermal Conditions and Ultraviolet Aging

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3472
Author(s):  
Ma ◽  
Pan ◽  
Liu ◽  
Jiang ◽  
Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Surface Layer ◽  
Flexural Strength ◽  
Aging Time ◽  
Uv Radiation ◽  
Aging Process ◽  
Epoxy Polymer ◽  
Polymer Concrete ◽  
Flexural Performance ◽  
Layered Beam

Epoxy polymer concrete (EPC) has found increasing applications in infrastructure as a rising candidate among civil engineering materials. In most of its service environments, EPC is inevitably exposed to severe weather conditions, e.g., violent changes in temperature, rain, and ultraviolet (UV) radiation. In this paper, we designed an accelerated aging test for EPC, which includes periodic variation of temperature and water spray, as well as intensive UV-light irradiation, imitating the outdoor environment in South China. The experimental results show that the flexural performance of EPC is found deteriorate with the aging time. An aging process equivalent to four years (UV radiation dose) results in up to 8.4% reduction of flexural strength. To explore the mechanisms of observed performance degradation, the EPC specimen in the four-point-bending test is considered as a layered beam. The analysis indicates that the loss of flexural load-carrying capacity of an aged EPC beam is dominated by the reduction of mechanical properties of the surface layer. The mechanical properties of the surface layer are closely associated with the aging of epoxy mortar, which can be approximated as a reciprocal function of the aging time. By introducing damage to the surface layer into the layered beam, the proposed model demonstrates a good ability to predict the residual flexural strength of EPC during the aging process

Study on Two-Step Aging Technology of 6082 Aluminum Bumper

2018 ◽  
Vol 764 ◽  
pp. 245-251
Author(s):  
Bei Ming Zhao ◽  
Miao Hu ◽  
Jun Zhu ◽  
Zhen Yu Han ◽  
Hou Qing Sun ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Process Parameters ◽  
Aging Temperature ◽  
Aging Process ◽  
Production Efficiency ◽  
Holding Time ◽  
Second Stage ◽  
Main Factors ◽  
6082 Aluminum Alloy

The influence of four parameters of two-step aging on the mechanical properties of 6082 aluminum alloy bumper was studied by orthogonal test. The results show that compared with the single stage aging, the two-step aging process can reduce the aging time and improve the production efficiency under the premise of the mechanical properties of the bumper meet the requirements. Among the four aging process parameters, the second stage aging temperature and holding time are the main factors that affect the final results, while the first stage aging temperature and holding time are secondary factors. The most suitable aging process parameters for the 6082 aluminum alloy bumper is (150 °C, 2 h) + (190 °C, 2.5 h). After two-step aging, the grain of the aluminum bumper is small and evenly distributed, leading to good mechanical properties. The generalized experiment shows that the application of the two-step aging process still has some limitations and needs to be further optimized and perfected.

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