scholarly journals Impact of high temperature on mortar mixes containing additives

2021 ◽  
Author(s):  
Kiran Devi ◽  
◽  
Babita Saini ◽  
Paratibha Aggarwal ◽  
◽  
...  
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Room Temperature ◽  
Cement Mortar ◽  
Calcium Nitrate ◽  
Cementitious Materials ◽  
Strength Properties ◽  
Exposure Temperature ◽  
Thermal Changes ◽  
And Performance

The structures may be exposed to fire or high temperature conditionally or accidentally. Alteration in the behavior of concrete structure is prospective under the exposure of elevated temperature. There is an urge to find the materials which can resist the alteration in physiochemical and strength properties of cementitious materials under high temperature. In the present study, the effect of elevated temperature on cement mortar consisting of additives i.e. accelerating admixtures, and stone waste i.e. stone slurry powder, was investigated and compared with specimens at room temperature. The aim of study was to examine the practicability of these additives under exposure to high temperatures. The mortar specimens were exposed to various temperatures i.e. 1500C, 3000C, 4500C and 6000C for the duration of one hour and compared with unheated samples. The change in mass, strength and micro-structure of mortar specimens at elevated temperature was studied. The environmental assessment and performance evaluation of various mortar mixes were also evaluated. The mass of mortar specimens reduced as the exposure temperature of specimens was raised. The residual strength of mortar increased up to a certain temperature afterward, it decreased. Stone slurry powder and calcium nitrate can be used individually and in combination to resist thermal changes.

Three-Dimensional Numerical Analysis for Bolted Flange Joints Considering Effect of Creep

2018 ◽  
Author(s):  
Lewen Bi ◽  
Lanzhu Zhang
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Numerical Analysis ◽  
Yield Strength ◽  
Room Temperature ◽  
Three Dimensional ◽  
Short Term ◽  
Flange Connection ◽  
Petroleum Chemical ◽  
Bolted Flange

Bolted flange joints are widely used in petroleum, chemical, nuclear and power industries, etc. With more and more devices are used at high temperature, the performance of flange connections becomes more complex, especially with creep of different components in flange connection. At elevated temperature, with the loss of bolt force and gasket force due to creep, the joints are prone to leak. Based on this, this paper analyzed the relaxation of bolt force at elevated temperature due to creep of bolt, flange and gasket separately and simultaneously. Besides, the influence of different initial installation stress of bolts was also studied. The results showed bolted flange joints relaxed due to gasket creep during early short term service. However, contribution of bolt and flange creep became more and more significant with the extension of time. With considering the creep of bolt, flange and gasket simultaneously, 50% to 60% of the bolt material yield strength at room temperature was recommended as the bolt initial installation stress for the joint case studied in this paper.

Deformation of an extruded nickel beryllide between room temperature and 820 °C

1991 ◽  
Vol 6 (12) ◽  
pp. 2653-2659 ◽  
Author(s):  
G.M. Pharr ◽  
S.V. Courington ◽  
J. Wadsworth ◽  
T.G. Nieh
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Elevated Temperature ◽  
Flow Stress ◽  
Strain Hardening ◽  
Room Temperature ◽  
High Temperature Strength ◽  
Compression Tests ◽  
Tension And Compression ◽  
Better Than

The mechanical properties of nickel beryllide, NiBe, have been investigated in the temperature range 20–820 °C. The room temperature properties were studied using tension, bending, and compression tests, while the elevated temperature properties were characterized in compression only. NiBe exhibits some ductility at room temperature; the strains to failure in tension and compression are 1.3% and 13%, respectively. Fracture is controlled primarily by the cohesive strength of grain boundaries. At high temperatures, NiBe is readily deformable—strains in excess of 30% can be achieved at temperatures as low as 400 °C. Strain hardening rates are high, and the flow stress decreases monotonically with temperature. The high temperature strength of NiBe is as good or better than that of NiAl, but not quite as good as CoAl.

300C Capable Digital Integrated Circuits in SiC Technology

2012 ◽  
Vol 717-720 ◽  
pp. 1261-1264 ◽  
Author(s):  
Amita Patil ◽  
Naresh Rao ◽  
Vinayak Tilak
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Elevated Temperature ◽  
Integrated Circuits ◽  
Room Temperature ◽  
Continuous Operation ◽  
Shift Register ◽  
Digital Integrated Circuits ◽  
Enhancement Mode

This paper pertains to development of high temperature capable digital integrated circuits in n-channel, enhancement-mode Silicon Carbide (SiC) MOS technology. Among the circuits developed in this work are data latch, flip flops, 4-bit shift register and ripple counter. All circuits are functional from room temperature up to 300C without any notable degradation in performance at elevated temperature. The 4-bit counter demonstrated stable behavior for over 500 hours of continuous operation at 300C.

Elevated Temperature Tensile Behavior of Nextel™ 720 Fibers

Materials ◽  
2003 ◽  
Author(s):  
D. M. Pai ◽  
S. N. Yarmolenko ◽  
E. Freeman ◽  
L. P. Zawada
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Room Temperature ◽  
Thermal Exposure ◽  
Strength Distribution ◽  
Tensile Behavior ◽  
Beneficial Effects ◽  
Elevated Temperature Tensile ◽  
Long Duration ◽  
Temperature Exposure

The tensile behavior of Nextel 720 fibers at elevated temperature was compared with room temperature results for both bare and monazite-coated fibers. While coated and uncoated fibers have nearly identical tensile strengths and Weibull moduli at room temperature, differences in response were seen at elevated temperature. Coated fibers tested at 1200°C were found to have a 40% drop in strength. Uncoated fibers at high temperature exhibited 55% less strength than at room temperature. However, the tensile strength distribution for uncoated fibers tested at high temperature exhibited two distinct populations, indicating two different failure mechanisms. One population showed a 50% drop while the other showed a 64% drop. The coating was thus found to have a protective effect in terms of short-duration high-temperature exposure. Further, the effect of soaking on strength was investigated by thermally soaking coated and uncoated fibers in air at 1200°C for 100 hours prior to tensile testing at elevated temperature. In this case, the long duration of thermal exposure appeared to eliminate the beneficial effects of the coating. Soaked fibers, both coated and uncoated, were found to have nearly identical strengths at 1200°C—a reduction of about 60%.

FANSTEEL 80 METAL

Alloy Digest ◽  
1981 ◽  
Vol 30 (11) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Electron Beam ◽  
High Temperature ◽  
Elevated Temperature ◽  
Electron Beam Melting ◽  
Room Temperature ◽  
Base Alloy ◽  
Heat Treating ◽  
High Quality

Abstract FANSTEEL 80 METAL is a columbium-base alloy containing nominally 1% zirconium. It is produced by electron-beam melting which gives it exceptionally high interstitial purity. It is several times stronger than pure columbium at elevated temperature; and this is without sacrificing the ease of fabrication associated with columbium. Fansteel 80 Metal can be fabricated easily at room temperature and high-quality ductile welds are possible. Its applications include nuclear, liquid metal loops and structures for high-temperature environments. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Cb-10. Producer or source: Fansteel Metallurgical Corporation. Originally published August 1966, revised November 1981.

Influence of Alumina Particles on Tribology of Autocatalytic Ni-P Coatings at High Temperature

2021 ◽  
Vol 9 (1) ◽  
pp. 1-25
Author(s):  
Sanjib Kundu ◽  
Suman Kalyan Das ◽  
Prasanta Sahoo
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Room Temperature ◽  
Adhesive Wear ◽  
Amorphous Structure ◽  
Nanocrystalline And Amorphous ◽  
Alumina Particles ◽  
Al2o3 Particles ◽  
Electroless Ni ◽  
Worn Surface

The present work considers the effects of incorporation of hard Al2O3 particles on the structure, microhardness, and tribological behavior of electroless Ni-P coatings at room temperature and elevated temperature. Ni-P (9% P) coating shows a typical amorphous structure that changes to a mixture of nanocrystalline and amorphous structure due to the addition of alumina particles. The incorporation of Al2O3 particles is found to enhance the overall hardness and wear resistance of the Ni-P coating. Exposure to high temperature during tribological tests acts as brief heat treatment, initiating microstructural changes in the coating which further increases the hardness of the deposit. The scanning electron micrograph of the worn surface of the coating reveals both abrasive and adhesive wear phenomena governing the wear mechanism at elevated temperature. The development of the oxide layer is another important characteristic of the coatings examined under high temperatures (around 500°C).

A Method for the Production of Large Sized Al-B4C-Al2O3np Nanocomposites through Liquid-State Process

2017 ◽  
Vol 753 ◽  
pp. 84-92
Author(s):  
Wei Liu ◽  
Qiu Lin Li ◽  
Wei Liu ◽  
Guo Gang Shu ◽  
Qi Sun ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Elevated Temperature ◽  
Ball Milling ◽  
Liquid State ◽  
Room Temperature ◽  
Milling Time ◽  
Mixed Powder ◽  
State Process ◽  
Semi Solid

The paper introduces a new method to produce large sized Al-B4C-Al2O3np composites, which combines ball milling to prepare Al2O3np/Al mixed powder and semi-solid casting to contribute the injection of Al2O3np/Al mixed powder into the melt. The deformation performance of Al2O3np and micro-Al through ball milling with different Al/Al2O3np ratios, different milling time and different balls were studied respectively. It was revealed that micro-Al particles were milled from twisted and crimpled foil pieces to shuttles with Al2O3np embedded on it through 4h milling with 10mm balls. And we consider it as the best bonding between Al2O3np and micro-Al we could attain. And a plate of 25kg of Al-B4C-Al2O3np composite was fabricated successfully with the injection of the Al2O3np/Al mixed powder. Spherical Al2O3np of 300nm and needle-like TiB2 with 200nm in radius and 800nm-4μm in length were found in SEM photographs. Tensile properties of Al-B4C-Al2O3np composites were tested at room temperature and high temperature. It was showed higher mechanical properties than Al-B4C composites at room temperature and elevated temperature. Particularly, a 40% increase of UTS of Al-15wt.% B4C-1wt.%Al2O3np at 350°C was observed.

Effect of Zr Addition on High Temperature Mechanical Properties of Near Alpha Ti-Al-Zr-Sn Based Alloy

2014 ◽  
Vol 783-786 ◽  
pp. 580-583 ◽  
Author(s):  
Murugesan Jayaprakash ◽  
De Hai Ping ◽  
Y. Yamabe-Mitarai
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Room Temperature ◽  
High Temperature Strength ◽  
Test Results ◽  
High Temperature Mechanical Properties ◽  
Ti Alloys ◽  
Zr Addition ◽  
And Performance ◽  
Compressive Tests

Titanium (Ti) alloys are widely used in aerospace industries successfully up to 600°C. Increasing the operating temperature and performance of these alloys would be very useful for fuel economy. Numerous numbers of research works has been focused on the improvement of the high temperature performances of Ti alloys. It has been well known that Zirconium (Zr) is one of the important solid-solution strengthener in Ti-alloys. In the present study, the effect of Zr addition on the microstructure and mechanical properties of the near–α Ti-Al-Zr-Sn based alloys has been investigated.The compression test results showed that Zr addition significantly improves both room temperature and high temperature strength. The results obtained were explained based on the microstructural observation, room temperature and high temperature compressive tests.

Electrical Characterization of Large Area 800 V Enhancement-Mode SiC VJFETs for High Temperature Applications

2009 ◽  
Vol 615-617 ◽  
pp. 715-718 ◽  
Author(s):  
Andrew Ritenour ◽  
Volodymyr Bondarenko ◽  
Robin L. Kelley ◽  
David C. Sheridan
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Threshold Voltage ◽  
Room Temperature ◽  
Electrical Characterization ◽  
Saturation Current ◽  
Large Area ◽  
Enhancement Mode ◽  
High Temperature Operation

Prototype 800 V, 47 A enhancement-mode SiC VJFETs have been developed for high temperature operation (250 °C). With an active area of 23 mm2 and target threshold voltage of +1.25 V, these devices exhibited a 28 m room temperature on-resistance and excellent blocking characteristics at elevated temperature. With improved device packaging, on-resistance and saturation current values of 15 m and 100 A, respectively, are achievable.

scholarly journals The Effect of Complex Modification on the Impedance of Cement Matrices

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 557
Author(s):  
Grigory Yakovlev ◽  
Černý Vít ◽  
Irina Polyanskikh ◽  
Anastasiya Gordina ◽  
Igor Pudov ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Negative Impact ◽  
Calcium Nitrate ◽  
Control Sample ◽  
Multiwall Carbon Nanotubes ◽  
Strength Loss ◽  
Cementitious Materials ◽  
Strength Properties ◽  
Cement Matrix

The research results presented in this article were obtained by joint scientific research on creatingcement materials with reduced impedance. It is known that functional additives added to impart electrically conductive properties have a negative impact on physical and mechanical characteristics of the material. This study suggests using the multiwall carbon nanotubes in the amount of 7% from binder mass as a functional additive. The results obtained prove that the addition of this amount of the modifier does not lead to a significant decrease of strength characteristics. Calcium nitrate in the amount of 1–7% was added in order to level the strength loss and to ensure the effective stable electrical conductivity. The multifunctionality of using this salt has been proven, which is manifested in the anti-frost and anticorrosive effects as well in enhancement of electrical conductivity. The optimal composition of the additive with 7% of carbon nanotubes and 3% of calcium nitrate ensures a reduced electrical impedance of cement matrix. The electrical conductivity was 2440 Ohm, while the decrease of strength properties was within 10% in comparison tothe control sample. The nature of changes in the microstructure were studied to determine the influence of complex modifications that showed significant changes in the morphology of the hydration products. The optimum electrical characteristics of cementitious materials are provided due to the uniform distribution of carbon nanotubes and the formation of a network of interconnected micropores filled with the solution of calcium nitrate that provides additional and stable electrical conductivity over time.

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