Effect of Heat Treatment on Thermomechanical Properties of Electron Beam-cured Epoxy Resins

2002 ◽  
Vol 10 (6) ◽  
pp. 467-480
Author(s):  
Zuo-Guang Zhang ◽  
Gang Sui ◽  
Wei-Hong Zhong ◽  
Zhi-Jie Sun
Keyword(s):  
Heat Treatment ◽  
Molecular Weight ◽  
Epoxy Resins ◽  
Crosslink Density ◽  
Thermomechanical Properties ◽  
Relaxation Peak ◽  
Heat Treated ◽  
Higher Temperature ◽  
Tan Δ ◽  
High Level

The effects of thermal post-treatment on EB-cured epoxy resins have been studied. Dynamic mechanical analyses were performed on samples which differed in EB radiation dose, initiator dosage, molecular weight and distribution. When the EB-cured epoxy resins were heated, the crosslink density increased. The glass transition temperature (Tg) was shifted to a higher temperature and the storage modulus (E’) remained at a high level in the heat-treated samples with increasing temperature. But when the temperature of heat treatment exceeded the trigger temperature of the initiator, an α'-relaxation peak derived from the local thermal curing network was observed in the tan δ curve. When the crosslink density induced by radiation increased, the effect of heat treatment was weakened and the temperature of the α′-relaxation peak gradually decreased. The initiator dosage and molecular weight played an important role in determining the Tg and E′ of heat-treated samples with approximately the same radiation crosslink density. When the polydispersity increased in the heat-treated samples with the same molecular weight, a higher temperature for the Tg and the α'-relaxation peak were both shown. The crosslink density and E′ at high temperatures were higher in the heat-treated samples with broad molecular weight distribution.

Effect of copper incorporation on phase transformation behavior of electroless nickel–phosphorous coating and its effect on the tribological behavior

2020 ◽  
pp. 146442072098160
Author(s):  
Abhijit Biswas ◽  
Suman Kalyan Das ◽  
Prasanta Sahoo
Keyword(s):  
Heat Treatment ◽  
Phase Transformation ◽  
Tribological Behavior ◽  
Electroless Nickel ◽  
Two Phase ◽  
Microstructural Changes ◽  
Treatment Conditions ◽  
Heat Treated ◽  
Higher Temperature ◽  
Effect Of Copper

The microstructural changes of electroless Ni–P–Cu coating at various heat-treatment conditions are investigated to understand its implications on the tribological behavior of the coating. Coatings are heat-treated at temperatures ranging between 200°C and 800 °C and for 1–4 h duration. Ni–P–Cu coatings exhibit two-phase transformations in the temperature range of 350–450 °C and the resulting microstructural changes are found to significantly affect their thermal stability and tribological attributes. Hardness of the coating doubles when heat-treated at 452 °C, due to the formation of harder Ni3P phase and crystalline NiCu. Better friction and wear performance are also noted upon heat treatment of the coating at the phase transformation regime, particularly at 400 °C. Wear mechanism is characterized by a mixed adhesive cum abrasive wear phenomena. Heat treatment at higher temperature (600 °C and above) and longer duration (4 h) results in grain coarsening phenomenon, which negatively influences the hardness and tribological characteristics of the coating. Besides, diffusion of iron from the ferrous substrate as well as greater oxide formation are noticed when the coating is heat-treated at higher temperatures and for longer durations (4 h).

Optimization of Heat Treatment Cycles for Automotive Parts Produced by Rheocasting Process

2006 ◽  
Vol 116-117 ◽  
pp. 505-508 ◽  
Author(s):  
Mario Rosso ◽  
Marco Actis Grande
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
High Performance ◽  
Treatment Cycle ◽  
Total Cost ◽  
Heat Treatment Cycle ◽  
Dimensional Precision ◽  
Heat Treated ◽  
Automotive Parts ◽  
High Level

This work aims at studying the possibility of optimising the heat treatment cycles of parts produced using the New Rheocasting process in order to reduce the total cost of the operation, attaining good mechanical properties for high performance parts. The mechanical properties and the microstructure features of the considered A 356 alloy and the relative produced parts have been analysed and studied on samples machined both from the as cast and from the heat treated compomnents. The obtained results showed the possibility of successfully modifying the T6 heat treatment cycle with economical benefits, maintaining at the same time comparable high level properties and performances, together with good dimensional precision.

Effect of Heat Treatment on Microstructure and Magnetic Properties of Strontium Hexaferrite Nanoparticles Prepared in Presence of Non-Ionic Surfactant

2013 ◽  
Vol 202 ◽  
pp. 193-205
Author(s):  
Nital R. Panchal ◽  
Rajshree B. Jotania
Keyword(s):  
Heat Treatment ◽  
Magnetic Properties ◽  
Tween 80 ◽  
Strontium Hexaferrite ◽  
Ionic Surfactant ◽  
Treatment Conditions ◽  
Heat Treated ◽  
Higher Temperature ◽  
Co Precipitation ◽  
Microstructure And Magnetic Properties

SrFe12O19 hexaferrite particles containing polyoxyethelene (20) sorbitan monolate (Tween-80) were synthesized by a chemical co-precipitation technique with a precipitator NH3.H2O. The prepared Sr-M hexaferrite precipitates were heat treated at various temperatures 650 oC, 750 oC, 850 oC, 950oC and 1100oC for 4 hrs in a muffle furnace. The obtained Sr-M powders were characterized by using various instrumental techniques, like FTIR, TGA, XRD, SEM, VSM and Mössbauer spectroscopy. Their physical as well as Magnetic properties were compared. It was observed from XRD results that heat treatment conditions play significant role in the formation of pure SrFe12O19 hexaferrite phase and also in the grain size. The estimated particle size is of the order of nanometer when suitable calcination temperature is applied. SEM micrographs show an increase in crystallite size of the resultant SrFe12O19 hexaferrite particles sintered at higher temperature (1100 oC). Mössbauer spectroscopic measurements were carried out at room temperature. Mössbauer analysis indicates the presence Fe3+ ions in the prepared strontium hexaferrite particles.

Chemical analysis of flavour volatiles in heat-treated milks

1978 ◽  
Vol 45 (3) ◽  
pp. 391-403 ◽  
Author(s):  
Haytham A. Jaddou ◽  
John A. Pavey ◽  
Donald J. Manning
Keyword(s):  
Mass Spectrometry ◽  
Heat Treatment ◽  
Molecular Weight ◽  
Gas Chromatography ◽  
Chemical Composition ◽  
Volatile Compounds ◽  
Raw Milk ◽  
Low Molecular Weight ◽  
Total Volatile ◽  
Heat Treated

SummaryThe effect of heat treatment of milk on low molecular weight, volatile compounds was studied in order to relate changes in the flavour of milks to changes in chemical composition. Milks were heat treated in a UHT plant for 3 or 90 s at 140 °C and stored at ambient temperature for periods up to 112 d. Volatile compounds in raw milk and in heated milks were isolated by a low temperature spray distillation technique and identified using gas chromatography and mass spectrometry. Cabbagey defects in heated milks are correlated with total volatile sulphur and it is concluded that the compounds H2S, COS, CH3SH, CS2 and (CH3)2S could be responsible for this defect.

Morphology of Carbon Micro-Coils

2004 ◽  
Vol 449-452 ◽  
pp. 205-208
Author(s):  
M. Fujii ◽  
S. Motojima
Keyword(s):  
Heat Treatment ◽  
Lattice Structure ◽  
Diffraction Method ◽  
Chemical Vapor ◽  
Amorphous Structure ◽  
Treatment Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Higher Temperature

The double helical carbon micro-coils were obtained by chemical vapor deposition. As-grown carbon micro-coils with amorphous structure were heat-treated at various temperatures up to 3000°C . By heat treatment, the shape of the coils was not changed. The morphology of these coils was observed in detail using electron microscope. The lattice structure was analyzed by X-ray diffraction method. Heat treatment temperature dependence of the magnetoresistance and the measurement of Raman spectra suggest that the coils heattreated at higher temperature are more highly graphitized.

scholarly journals Experimental Investigation Of Modified Heat Treatment Of AK64-Type Al-Si-Cu Sand Cast Alloy

2015 ◽  
Vol 60 (3) ◽  
pp. 2397-2402 ◽  
Author(s):  
L.H. Cupido ◽  
P.L. Żak ◽  
N. Mahomed ◽  
J. Lelito ◽  
G. Piwowarski ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Experimental Investigation ◽  
Cast Alloy ◽  
Eutectic Reaction ◽  
Artificial Ageing ◽  
Sand Cast ◽  
Cu Alloy ◽  
Heat Treated ◽  
Dendrite Network ◽  
Higher Temperature

Abstract An experimental investigation was conducted to observe and analyze the microstructural evolution of phases present in the AK64 Al-Si-Cu alloy subjected to a modified T6 heat treatment (HT). The AK64 alloy1 is the Polish alternative of the A319.0 ASM standard aluminium alloy. The modified T6 HT schedule with a higher temperature and shorter duration was applied in the solutioning process and lower quenching and higher artificial ageing temperature than the prescribed by the ASM standard were used. The cooling curves registered during the liberating of overheating and solidifying processes give important information on nucleation temperatures for the Al dendrite network, Al-Si eutectic reaction and precipitation of Cu-rich phases. Comparison of the as-cast and heat treated microstructures revealed predicted microstructural changes and also partial fragmentation of the Fe-rich phases was observed after the application of the modified HT programme.

Changes in the wood-water interactions of mahogany wood due to heat treatment

Holzforschung ◽  
2020 ◽  
Vol 74 (9) ◽  
pp. 853-863
Author(s):  
Fan Zhou ◽  
Zongying Fu ◽  
Xin Gao ◽  
Yongdong Zhou
Keyword(s):  
Heat Treatment ◽  
Environmental Temperature ◽  
Treated Wood ◽  
Fiber Saturation Point ◽  
Surface Wettability ◽  
Resonance Spectroscopy ◽  
Saturation Point ◽  
Fiber Saturation ◽  
Heat Treated ◽  
Higher Temperature

AbstractMahogany wood (Swietenia macrophylla King) was thermally modified by heating at various temperatures. The wood-water-related parameters of the heat-treated wood, including fiber saturation point, equilibrium moisture content, moisture excluding efficiency, hygroscopic hysteresis, swelling, anti-swelling efficiency, water adsorption, and surface wettability were determined to clarify the mechanism of heat treatment to reduce wood hygroscopicity. The wood treated at a higher temperature demonstrated a more significant decrease in hygroscopicity. The reduction in hygroscopicity of the heat-treated wood was partially diminished as the moisture excluding efficiency decreased in the absorption and desorption processes caused by the changes in environmental temperature and relative humidity. The fiber saturation point (determined by nuclear magnetic resonance spectroscopy), surface free energy, and the surface wettability of wood were reduced by heat treatment, resulting in the decreased hygroscopicity of the heat-treated wood. Mahogany wood became more insensitive to the influence of moisture due to the heat treatment, and this effect was more distinct for wood treated at a high temperature.

scholarly journals Effect of heat treatments on superconducting properties and connectivity in K-doped BaFe2As2

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chiara Tarantini ◽  
Chongin Pak ◽  
Yi-Feng Su ◽  
Eric E. Hellstrom ◽  
David C. Larbalestier ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Specific Heat ◽  
High Purity ◽  
Heat Treatments ◽  
Treatment Temperature ◽  
Vortex Pinning ◽  
Distribution Analysis ◽  
Transmission Electron ◽  
Heat Treated ◽  
Higher Temperature

AbstractFe-based superconductors and in particular K-doped BaFe2As2 (K-Ba122) are materials of interest for possible future high-field applications. However the critical current density (Jc) in polycrystalline Ba122 is still quite low and connectivity issues are suspected to be responsible. In this work we investigated the properties of high-purity, carefully processed, K-Ba122 samples synthesized with two separate heat treatments at various temperatures between 600 and 825 °C. We performed specific heat characterization and Tc-distribution analysis up to 16 T and we compared them with magnetic Tc and Jc characterizations, and transmission-electron-microscopy (TEM) microstructures. We found no direct correlation between the magnetic Tc and Jc, whereas the specific heat Tc-distributions did provide valuable insights. In fact the best Jc-performing sample, heat treated first at 750 °C and then at 600 °C, has the peak of the Tc-distributions at the highest temperatures and the least field sensitivity, thus maximizing Hc2. We also observed that the magnetic Tc onset was always significantly lower than the specific heat Tc: although we partially ascribe the lower magnetization Tc to the small grain size (< λ, the penetration depth) of the K-Ba122 phase, this behaviour also implies the presence of some grain-boundary barriers to current flow. Comparing the Tc-distribution with Jc, our systematic synthesis study reveals that increasing the first heat treatment above 750 °C or the second one above 600 °C significantly compromises the connectivity and suppresses the vortex pinning properties. We conclude that high-purity precursors and clean processing are not yet enough to overcome all Jc limitations. However, our study suggests that a higher temperature Tc-distribution, a larger Hc2 and a better connectivity could be achieved by lowering the second heat treatment temperature below 600 °C thus enhancing, as a consequence, Jc.

Effect of a Complex Heat Treatment on the Structure of 300M Steel

1981 ◽  
Vol 39 ◽  
pp. 312-313
Author(s):  
R. Padmanabhan ◽  
W. E. Wood
Keyword(s):  
Heat Treatment ◽  
Metal Carbides ◽  
Austenite Grain Size ◽  
300M Steel ◽  
Heat Treated ◽  
Strain Fracture ◽  
Prior Austenite Grain Size ◽  
Short Time ◽  
Final Tempering ◽  
Similar Yield

Intermediate high temperature tempering prior to subsequent reaustenitization has been shown to double the plane strain fracture toughness as compared to conventionally heat treated UHSLA steels, at similar yield strength levels. The precipitation (during tempering) of metal carbides and their subsequent partial redissolution and refinement (during reaustenitization), in addition to the reduction in the prior austenite grain size during the cycling operation have all been suggested to contribute to the observed improvement in the mechanical properties. In this investigation, 300M steel was initially austenitized at 1143°K and then subjected to intermediate tempering at 923°K for 1 hr. before reaustenitizing at 1123°K for a short time and final tempering at 583°K. The changes in the microstructure responsible for the improvement in the properties have been studied and compared with conventionally heat treated steel. Fig. 1 shows interlath films of retained austenite produced during conventionally heat treatment.

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