Reactions occurring in post heat-treated sialons: On the thermal stability of α-sialon

1996 ◽  
Vol 16 (8) ◽  
pp. 873-883 ◽  
Author(s):  
Zhijian Shen ◽  
Thommy Ekström ◽  
Mats Nygren
Keyword(s):  
Thermal Stability ◽  
Heat Treated ◽  
Thermal Stability Of

Microstructure and thermal stability of amorphous materials in the GeS2−La2S3 system

1991 ◽  
Vol 6 (12) ◽  
pp. 2694-2700 ◽  
Author(s):  
Prashant N. Kumta ◽  
Subhash H. Risbud
Keyword(s):  
Thermal Stability ◽  
Amorphous Materials ◽  
Fiber Optic ◽  
Molecular Level ◽  
Infrared Region ◽  
Mid Infrared ◽  
Heat Treated ◽  
Stable Glasses ◽  
Microstructural Studies ◽  
Thermal Stability Of

GeS2 is known to be a good chalcogenide glass former with a transmission cutoff at 11 μm and has been studied for fiber optic application in the mid infrared region. The rare earth sulfides, oxysulfides, and oxides (La–Er) form reasonably good and stable glasses when mixed with chalcogenides such as Ga2S3. In this work, glass formation was studied in the GeS2−La2S3 system. Two compositions containing 60 mol % and 92.5 mol % GeS2, respectively, were analyzed, and the effects of composition on the microstructure and thermal stability of these glasses were investigated. Microstructural studies were conducted on the as-prepared and heat-treated glasses using TEM and SEM/EDXA. Glasses rich in GeS2 exhibited primary (6–88 nm) and secondary (3–13 nm) phase separation at the molecular level. Differential thermal analysis performed on these glasses indicated glass transition temperatures (Tg) of 510 °C and 420 °C for the two compositions studied. The glasses were stable and the (Tg) was observed to decrease with increasing contents of GeS2 in these glasses.

scholarly journals Effects of aluminum sulfate soaking pretreatment on dimensional stability and thermostability of heat-treated wood

2020 ◽  
Author(s):  
Lijie Qu ◽  
Zhenyu Wang ◽  
Jing Qian ◽  
Zhengbin He ◽  
Songlin Yi
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Thermal Degradation ◽  
Structural Changes ◽  
Aluminum Sulfate ◽  
Treated Wood ◽  
Treatment Temperature ◽  
Chinese Fir ◽  
Heat Treated ◽  
Thermal Stability Of

Abstract Acidic aluminum sulfate hydrolysis solutions can be used to catalyze the thermal degradation of wood in a mild temperature environment, and thus reduce the temperature required for heat treatment process. To improve the dimensional and thermal stability of Chinese fir during heat treatment at 120 °C, 140 °C and 160 °C, this study investigated the effects of soaking pretreatment with 5%, 10% and 15% aluminum sulfate on the chemical and structural changes of the heat-treated Chinese fir. The results indicated that the samples treated at 15% aluminum sulfate concentration and 160 °C heat treatment achieved the best dimensional and thermal stability. Chemical analyses by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) indicated that the catalysis of aluminum sulfate resulted in degradation of hemicelluloses during the heat treatment, and an increase in the soaking concentration and heat treatment temperature also affected the thermal degradation of celluloses. The scanning electron microscope (SEM) and mass changes test results proved that the hydrolyzed aluminum flocs mainly adhered to the inner wall of the wood tracheid as spherical precipitates, and when the soaking concentration reached 10% and 15%, a uniform soaking effect could be achieved. The thermogravimetric (TG) analysis revealed the soaking pretreatment effectively improved the thermal stability of the heat-treated wood by physically wrapping and promoting the formation of a carbon layer on the wood surface during heat treatment. Thus, aluminum sulfate soaking pretreatment exerted a great effect on the dimensional and thermal stability of wood, allowing heat treatment to be performed at a lower temperature.

Chemical and Thermal Stability of Multiple Ions Doped Non-Stoichiometric Nanoapatite Heat-Treated in CO2 and Air Atmospheres

2014 ◽  
Vol 925 ◽  
pp. 77-81
Author(s):  
K. Jamuna Thevi ◽  
Mohammed Rafiq Abdul Kadir ◽  
Hendra Hermawan
Keyword(s):  
Thermal Stability ◽  
Nanocrystalline Phase ◽  
Secondary Phases ◽  
Wet Precipitation ◽  
Carbonate Ions ◽  
Precipitation Technique ◽  
Heat Treated ◽  
Phase Pure ◽  
20 Nm ◽  
Thermal Stability Of

Nanostructured apatite has been widely used as a bone substitute material due to its close resemblance to human bone mineral. To further mimic biological apatites, multiple ions doped non-stoichiometric nanoapatite has been studied. A nanosized apatite (NAp-2) containing Mg (1.09 wt%), Na (0.15 wt%), K (0.008 wt%) and CO32- (5.18 wt%) was synthesized by a wet precipitation technique. The presence of these ions in NAp-2 was detected using ICP. Broad diffraction peaks of XRD results indicated the presence of nanocrystalline phase pure NAp-2. The primary particle size of the resulted powder was ~ 20 nm, typical of bone crystal size, estimated using Scherrers equation. Based on CHN results, the NAp-2 powders showed a total loss of 51 and 78% of carbonate ions when heat-treated at 900°C in both CO2 and air atmospheres, respectively. This indicates that the heat-treatment in CO2 flux has reduced the carbonate ions lost from the NAp-2. A highly crystalline HA phase was formed in the ionic doped NAp-2 without secondary phases, indicating a thermal stability of this powder at 900°C in CO2 and air atmospheres. Thus, this study demonstrated that a phase pure multiple ions doped nanoapatite was synthesized using a wet precipitation technique.

Thermal Degradation Study of Functionalized MWNT Reinforced Segmented Polyurethane Membrane

2006 ◽  
Vol 38 (3) ◽  
pp. 261-271 ◽  
Author(s):  
S. Mondal ◽  
J. L. Hu
Keyword(s):  
Thermal Stability ◽  
Thermal Degradation ◽  
Nitrogen Atmosphere ◽  
Segmented Polyurethane ◽  
Degradation Study ◽  
Heat Treated ◽  
Different Temperatures ◽  
Increasing Temperature ◽  
Thermal Stability Of ◽  
Mwnt Content

The thermal degradation of polytetramethylene glycol (PTMG, Mn 1/42900) based polyurethane (PU), along with four different weight contents (such as 0.25, 0.50, 1.0, and 2.5 wt%) of functionalized multiwalled nanotube (MWNT) reinforced PUs are studied in air as well as in nitrogen atmosphere. The degradation results are reported in 10 and 50% weight loss and derivative of thermogravimetry (DTG). As expected, PUs are thermally more stable in nitrogen than in air. However, the influence of MWNT content on thermal stability is unclear. At 0.25 and 0.50 wt% of MWNT content, thermal stability declined and a further increase of MWNT improved the thermal stability of PU. Fourier-transform infrared (FTIR) analysis is also performed for untreated and heat treated films in order to understand the degradation at different temperatures. Free C1/4O stretching neck dimension increases with increasing temperature which signifies breaking of H-bonding detected by FTIR measure ments.

Thermal Stability of Cu and Cu2O Nanoparticles in a Polyimide Film

2008 ◽  
Vol 8 (9) ◽  
pp. 4822-4825 ◽  
Author(s):  
Jae-Youn Choi ◽  
Wenguo Dong ◽  
Dong Joo Choi ◽  
Chong S. Yoon ◽  
Young-Ho Kim
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Polyimide Film ◽  
Cu Nanoparticles ◽  
Transmission Electron ◽  
Heat Treated ◽  
Cu Film ◽  
Vis Spectroscopy ◽  
Cu2o Nanoparticles ◽  
Thermal Stability Of

Nanoparticles of Cu or Cu oxide dispersed in a polyimide (PI) film were fabricated by reaction of polyamic acid with a thin Cu film during imidization. In this paper, the thermal stability of the Cu or Cu oxide nanoparticles was investigated under various atmospheres. The PI/nanoparticle composites were heat-treated at 140 °C and 250 °C in air, N2, Ar, and 5% H2 atmospheres. Nanoparticles in the PI film were characterized by UV-VIS spectroscopy and transmission electron microscopy. The optical absorption peaks originating from Cu or Cu2O nanoparticles were changed by heat-treatment in different atmospheres. When Cu nanoparticles were oxidized by heat-treatment in air, the surface plasmon resonance (SPR) peak originating from the Cu nanoparticles disappeared. The quantum confined absorption peak of Cu2O was not affected by heat-treatment in N2 or Ar. Cu2O nanoparticles were reduced by heat-treatment at 250 °C in 5% H2 atmosphere and a new SPR peak appeared. Our results show that Cu nanoparticles are easily oxidized and highly dense Cu nanoparticles can be formed by reducing Cu2O nanoparticles.

Microstructure and Phase Composition of Iridium Coating on Molybdenum after Heat Treatment at 1400°C

2011 ◽  
Vol 189-193 ◽  
pp. 688-691 ◽  
Author(s):  
Wang Ping Wu ◽  
Zhao Feng Chen ◽  
Xin Lin
Keyword(s):  
Phase Transition ◽  
Heat Treatment ◽  
Thermal Stability ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface And Interface ◽  
Heat Treated ◽  
Glow Plasma ◽  
Ar Gas ◽  
Thermal Stability Of

Iridium (Ir) could be taken as high temperature protective coating for the refractory metals. Ir coating was deposited on the surface of molybdenum (Mo) substrate by double glow plasma. Thermal stability of the coating was investigated at 1400°C for 90 min, while Ar gas was inputted to hold the vacuum pressure. The microstructure of the surface and interface of the Ir coating were observed by SEM and TEM. The phase transition of the coating was determined by X-ray diffraction. Many micropores and microbubbles appeared in the surface of the as-heat treated coating. The interfacial reaction between the Mo substrate and Ir coating occurred during heat treatment, and Ir21.5Mo8.5 phase was formed at 1400°C. The experimental results indicated that the integrity of the Ir coating was not degraded after heat treatment.

The Development of Thermally Stable Sealing Glass in the BaO–B2O3–SiO2 System for Planar SOFC Applications

2008 ◽  
Vol 5 (3) ◽  
Author(s):  
Lian Peng ◽  
Qingshan Zhu
Keyword(s):  
Thermal Stability ◽  
Coefficient Of Thermal Expansion ◽  
Glass Network ◽  
Good Thermal Stability ◽  
Sealing Material ◽  
Heat Treated ◽  
Thermal Stability Of ◽  
Sealing Glass ◽  
B2o3 Glass

The purpose of the present paper is to study the influence of glass composition on the thermal stability in the SiO2–B2O3–BaO system, and three glasses were consequently investigated. Although Glass A has a coefficient of thermal expansion (CTE) that shows the best match with those of anode and electrolyte materials of solid oxide fuel cells (SOFCs), the thermal stability of Glass A is quite poor, where after being heat treated at 800°C for only 8h, the CTE of the glass increased more than 24%. The change of the CTE value was mainly attributed to the fast crystallization that formed high CTE value phases such as BaB2O4 and Ba2Si3O8. In order to improve the thermal stability, BaO in Glass A was replaced by B2O3 (Glass B) and SiO2 (Glass C). It was found that the decrease in the BaO content improved the thermal stability of the resultant glasses. Glass B showed less than 8% change of the CTE during annealing time at 800°C, while Glass C exhibited superior long-term thermal stability, where the change of the CTE was within the equipment detection limit after being heat treated for 300h at 800°C. The good thermal stability of Glass C was believed to be due to the formation of a more compact glass network after the substitution as compared with that of Glass A. The good thermal stability makes Glass C attractive to be used as the sealing material for SOFC applications.

Strength properties and dimensional stability of particleboards with different proportions of thermally treated recycled pine particles

Holzforschung ◽  
2016 ◽  
Vol 70 (5) ◽  
pp. 467-474 ◽  
Author(s):  
Paulo Ivan Andrade ◽  
Solange de Oliveira Araújo ◽  
Duarte Miranda Neiva ◽  
Benedito Rocha Vital ◽  
Angélica de Cássia Oliveira Carneiro ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Dimensional Stability ◽  
Lignin Content ◽  
Strength Properties ◽  
Raw Material ◽  
Heat Treated ◽  
Wood Particles ◽  
Partial Degradation ◽  
Thermal Stability Of

Abstract Wood-based panels made of waste and recycled raw material are lacking of dimensional stability. The aim of this study is to evaluate the potential beneficial effect of heat treatment (HT) on the properties of particleboards produced from waste of Pinus sp. used for packaging. The wood particles were heat treated at 180°C, 200°C and 220°C after grinding, and panels were produced with incorporation of 25%, 50%, 75% and 100% HT particles. The materials served as reference were particles without HT. Mass loss at 180°C and 200°C was small but increased significantly to 10.6% at 220°C. The HT caused a partial degradation of hemicelluloses, thereby the relative lignin content increased from 29.7% to 37.8% for the HT220°C samples. Thermogravimetry revealed higher thermal stability of the HT particles. The equilibrium moisture content decreased with HT, e.g. panels with HT220°C showed 30% lower compared to the reference. Swelling of the panels was lowered by 30% (panel with 75% HT material) compared to the reference. The results with HT pine were successful in terms of dimensional stability and lower hygroscopicity; however, the panels lost some strength properties.

Sign in / Sign up

Export Citation Format

Share Document